hp-pnesg-1_using the hp esg-d series of rf signal generators and the hp 8922 gsm test set
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Using the HP ESG-D se ries of
RF s ignal gene rators an d theHP 8922 GSM Tes t S e t for
GSM App licatio n s
Product Note ESG-1
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2
page
1 . In tro du c ti on 3
2 . In t ro d u ct io n t o GS M 3
3. Generating a 0.3 GMSK modu lated burst s ignal 10
for GSM (GSM 900, DCS 1800 & PCS 1900) usin g
the HP ESG-D series s ign al generator
4 . D at a Ge n e ra ti on 15
4.1 Choosing Data Pa tt erns
4.2 Single / Cont inuous Data pat tern s
4.3 Data Dependencies
4.4 Generating long data pattern s,
such as a GSM superframe
5. Triggerin g a GSM frame 23
6 . Cus tom i zi ng the GSM Mode 26
7 . Adjacent Broadcas t Channe l Generati on 28
using the HP ESG-D ser ies s ignal gen erator
and the HP 8922 GSM Test Se t
8. Using the HP ESG-D series s ignal generator 31
and th e HP 8922 GSM Test Se t to carry out
GSM receive r tests
8.1 Receiver Co-Cha nn el Rejection
8.2 Receiver Adjacent Ch an nel Rejection
8.3 Receiver Intermodulation Rejection
9 . Conver ti ng ARFCNs i n t o abs o lu t e f requency 39
values for GSM systems
10. Glossary of terms 40
11. Top l ine Speci fi cat ions 41
12. Related Li terature 42
13. Warranty Information 42
14. Presales address l is t , Disc la imer 43
Table o f Contents
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The HP ESG series RF signal generators from Hewlett-Packard Company
provides pr ecise frequen cy and level contr ol, modulat ion (AM, FM, P ha se
Modulat ion an d Pu lse Modulat ion), a choice of frequen cy covera ge from
250 kHz to 1, 2, 3 or 4 GHz and an easy-to-use interface. The digital family,
the H P E SG-D series, adds versa tile I/Q digita l modulation capabilities and
six built-in communications standards (GSM, DECT, TETRA, NADC, PHS
an d PDC) are provided with th e optional IQ baseband genera tor (Options
UN3 & UN 4) . Accessible at t he t ouch of a but ton, these built-in commun ica-
tions personalities ar e easy to configure to meet u ser-defined test require-
ments. The HP ESG-D series provides operators measurement versatility by
offering a choice of inter nal or extern al da ta generat ion, a nd flexible framing,
timeslot a nd power burst profile configurat ion capabilities.
The pur pose of this product note is to show how to use the H P E SG-D series
signal generat ors to generate a digita lly modulated signa l for the Global
Syst em for Mobile Commu nicat ions (GSM). Deta ils will also be given on how
the HP ESG-D series signal generat ors can be used with th e HP 8922 GSM
Test Set for GSM applications.
The Global System for Mobile Communications (GSM) is the most successful
digital cellular system in operat ion today. Alth ough GSM origina ted in
Eu rope, it is quickly gaining world-wide acceptan ce and is being adopted as a
standa rd in ma ny countr ies.
GSM uses 0.3 Gauss ian Minimu m S hift Keying (0.3 GMSK) modulat ion a nd a
bit ra te of 270.833 kbits/second. The "tr ellis" diagr am , shown below, shows a
repr esenta tion of GMSK modulat ion. It shows time on th e X-axis and ph ase
on the Y-axis. This allows th e examina tions of th e pha se tr an sitions with
different symbols or bits.
GMSK is a special type of digita l FM. Ones and zer os are r epresent ed by shift-
ing the RF carrier by plus or m inus 67.708kHz. This frequency shift h as acorr esponding shift in ph ase (relative to the u nm odulated carr ier) which
conveys information.
1. Introduc tion
2. Introduction to GSM
Figure 1a.
Trell is diagram of GMSK.
Time
Phase
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Broadcast
Channel
BCH
Traffic
Channel
To
BSC
Abis
Interface
TCH BTS
Uplink
Down
link
GSM
GSM
GSM
Figure 2 .
Diagram o f GSM cell .
Figure 1b.
0.3 GMSK
Data
Frequency
Phase
+67.708 kHz
-67.708 kHz
270.833kB/s
+90 -90I
Q
If a long series of ones wer e sent , th e resu lt would be a series of positive
phas e tr ans itions of 90 degrees per bit. If a long series of zeros were sent ,
ther e would be a const an t declining phas e of 90 degrees per bit. Typically,
there would be intermediate tr ansmissions with r andom data.
The modulation spectrum is reduced by applying a Gaussian pre-modulation
filter. This slows down th e ra pid frequency tra nsitions which would other wise
sprea d energy into adjacent chan nels. When Ga ussian filtering is applied, the
phase makes slower direction changes and this prevents the phase trajectory
from m eeting its 90 degree tar get points. The exact pha se tr ajectory is very
tightly contr olled - the GSM s pecifications allow no more t ha n 5 degrees rm s
and 20 degrees peak deviation from th e ideal tr ajectory. The 0.3 ment ioned
above describes the bandwidth of the Ga ussian filter with relat ion t o the bit
ra te, and is m ore commonly called the fi lter alpha or th e bandwidth-by-
time produc t (BbT).
The GSM system consists of Mobile St ations (MS), both h and-held porta bles
and mobiles mounted in a car, which comm unicate with the Ba se Sta tionSystem (BSS) over th e RF a ir int erface. The BSS t ypically consists of a Ba se
Tran sceiver System (BTS) and a Base St ation Controller (BSC) which are
connected by a link called the Abis interface. The Abis interface is often a
microwave link, but can also be a cable or an optical fibre.
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The BTS is fitted with a n umber of tr an smitt er/receiver (or tr ans ceiver)
modules, th e num ber of which deter mines th e num ber of frequency chann els
tha t can be used in th e GSM cell. Its exact configur ation varies depending on
the num ber of users expected in the cell. All BTSs contin ually produce a
Broadcast Ch ann el (BCH). The BCH is like a beacon - it allows mobiles t o find
the GSM network. The BCH consists of various par ts for frequency corr ection,
synchronization, control and access. The BCH is received by all mobiles in the
cell, wheth er th ey are on a call or n ot.
Mobiles on a call use a TCH (Tr affic Cha nn el). The TCH is a tw o w ay chan-
nel used to exchan ge speech informat ion between t he mobile and base-stat ion.
Usin g Fr equen cy Division Mult iple Access (FDMA), informa tion is divided
into the uplink and downlink, depending on its direction of flow. The uplink is
for m obile tr an smission and t he downlink is for bas e stat ion tr ans mission.
With in each band th e cha nnel nu mbering scheme is the sa me, however, the
uplink a nd downlink bands ar e 45 MHz apart.
Each ba nd is t hen divided into 200 kHz chann els called Absolute Radio
Fr equency Chann el Number s (ARFCN). In addition to frequency division,
time is also divided into segments using Time Division Multiple Access
( TDMA).
51Frames
FCH Frames 0, 10, 20, 30, 40
SCH Frames 1, 11, 21, 31, 41
BCCH Frames 2-5CCCH Frames 6-9, 12-19
SDCCH Frames 22-29, 32-39
SACCH Frames 42-49
Frame 50 is idle
2 3 00 11
Figure 3 .
Diagram of BCH.
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Each ARFCN is shar ed between up to 8 mobiles. Since ther e are a ma ximum
of eight u sers per frequen cy, there a re eight timeslots (TS) per GSM frame.
Each t imeslot las ts 576.92s an d cont ains 156.25 bits of inform at ion,
alth ough only 148 of th ese bits are us ed for da ta. The r emain ing bits a re used
for "gua rd" time. The patt ern r epeats, giving th e users anoth er timeslot each
frame. Ther efore, each mobile (user) uses t he ARFCN for one t imeslot a nd
then wait s for its tu rn t o come round aga in in the next fram e.
The mobile tran smitt er tu rns on only dur ing its active timeslot. The require-
ment t o tr an smit in only one single timeslot an d stay idle dur ing the rema in-
ing seven timeslots results in very tight dema nds on th e switching on an d off
of the RF power. If a mobile station does not perform according to the specifi-
cations , it will distu rb other mobile sta tions in adjacent t imeslots a nd on
adjacent chan nels. The GSM specifications m ake su re a mobile's emissionsrema in in its a ssigned channel by specifying a power-versus-time t emplate,
shown in Figure 5. During the centra l, or "useful", part of the TDMA burst
(corresponding to 147 bits) when dat a is being tran smitt ed, the mobile has t o
cont rol its output t o within +/1dB of the mean value. This pulsed tran smis-
sion is not only defined for the mobile station but is also generally defined for
base stations.
+1.0 dB
1.0 dB
+4 dB
6 dB
30 dB
70 dB
6 dB
30 dB
70 dB
147 "Useful" Bits
542.72s
148 "Active" Bits, 546.42s
3 57 1 26 1 57 3
10s 8s 10s 10s 10s8s
Power
Time
Figure 5 .
GSM TDMA Burst
Figure 4 .
Diagram of ARFCNs.
1 2 3
45
6
3
4 5 6
70
1
2
Time
Frequency
Amplitude
ARFCN
Timeslot
Physical Channel is an
ARFCN and Timeslot
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The ETSI GSM 05.05 specifications also define the Adjacent Channel Power
(ACP) performan ce required by both m obile and ba se st at ions. The ACP spec-
ificat ions define the per form an ce required by the mobile and base st ations
outside their a ssigned chan nels. The ACP is usua lly defined at 1 chan nel
(200kHz), 2 cha nn el (400kHz), 3 chan nel (600kHz), etc. offset s from t he
assigned channel. Both t he modulation process and th e power ra mping up
and down (switching tran sients) affect th e outpu t RF spectru m. The required
ACP per form ance due t o these two effects is defined in t he E TSI GSM 05.05
specifications. The diagram and table below illust ra te th e excellent ACP
perform an ce available with th e HP ESG-D signa l generat or (configured with
Option UN3 or Option UN4). It can clear ly be seen from th e table th at th e
HP ESG-D complies with t he E TSI specificat ions.
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Table 1: Sum mary of HP ESG-D GSM ACP performan ce vs. ETSI GSM 05.05 recomm en datio ns
(ACP given in dBc, except where stated otherwise)
Spectrum due to modulation Spectrum due to switching
Offset from carrier (kHz) 200 400 600 1,200 200 400 600 1,200
ETSI spec.
(30 kHz measurementbandwidth)BS (at max power) 30 60 70 73 --- 57 67 74MS (at max power) 30 60 66 66 --- 23 dBm 26 dBm 32 dBm
HP ESG-D spec.
(30kHz measurementbandwidth) 37 71 81
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As ment ioned ear lier, eight time-slots ma ke up a GSM fra me. Fra mes ar e
th en grouped together t o ma ke multifram es. Speech mu ltifra mes (such as a
TCH) consist of 26 fra mes, while signaling data mult ifra mes (such as a BCH)
ar e ma de up of 51 fra mes. A superframe consists of 26 or 51 m ultifram es.
How are GSM, DCS1800 and P CS1900 different?GSM is a family of digital cellular systems. The term GSM can be used collec-
tively to describe the GSM900 and DCS1800 sta ndar ds. GSM900 is the origi-
na l GSM system, using frequencies in th e 900 MHz ban d an d is designed for
wide area cellular operat ion. DCS1800 is an a dapt ation of GSM900. Creat ing
DCS1800 involved widening th e bands assigned t o GSM and m oving them up
to 1.8 GHz. To avoid confusion, the chan nel nu mber s (ARFCN ) used for
GSM900 cha nnels r un from 1 to 124, and th e ARFCNs for DCS1800 ru n from
512 to 885. With wider frequency allocation, leading to more channels,
DCS1800 is able to cope with higher u ser dens ities. DCS1800 mobiles ar e
also designed for lower outpu t powers (up to 1W), so cell sizes have t o be
sma ller, meaning even higher densities. In all other respects, GSM900 and
DCS1800 are th e sam e. The GSM Phase I I specifications (a r evised an d re-
writt en sta nda rd) brings the two systems even closer. GSM900 gets addi-
tional bandwidth a nd chann els, called E-GSM (Extended ba nd GSM) and
lower power cont rol levels for mobiles, allowing micro-cell opera tion. These
two featur es allow increased user den sities in GSM systems. Ph ase II also
ma kes pr ovision for th e addit ion of new services on GSM a nd DCS1800.The a ddition of specific services such as dat a, fax an d dua l mode opera tion is
curren tly being defined in what is referred to as Ph ase II+. In th e USA, bands
have been released ar ound 2 GHz for a PCS (Personal Commun icat ions
System). The ready availability of GSM equipment a nd expertise ha s ma de
GSM at 1.9GHz very att ra ctive for m any operat ors. In t echnical term s
PCS1900 will be identical to DCS1800 except for frequency allocation and
power levels.
6.12s
3 1 1 326 bits 57 bits57 bits
Control
bit
Control
bit
Midamble Guard
Period
DataData
8.25
bits
Tail
bits
Tail
bits
120ms
4.615ms
576.92 s
Superframe
Multiframe
Frame
Timeslot(normal burst)
26 Frames
51 Multiframes
8 Timeslots
156.25 Bits
Figure 7 .
Diagrams of Frames,
mult i frames, superframes.
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Table 2: Sum mary of GSM system p aramete rs
Phase 1GSM900
Uplink Frequency 890 to 880 to 1710 to 1710 to 1850 toRange 915 MHz 915 MHz 1785 MHz 1785 MHz 1910 MHz
Downlink 935 to 925 to 1805 to 1805 to 1930 toFrequency Range 960 MHz 960 MHz 1880 MHz 1880 MHz 1990 MHz
Voice Coder 13 kBit/s Full Rate 13 kBit/s, 13 kBit/s Full Rate 13 kBit/s, 13 kBit/sBit Rate Half Rate 5.6 kBit/s Half Rate 5.6 kBit/s
TX/RX Spacing (Freq.) 45 MHz 45 MHz 95 MHz 95 MHz 80 MHz
Mobile Power 0 - 15 2 - 19 0 - 13 0 - 15 0 - 15, 30, 31Control Steps
Mobile Max Power 20W 8W/39 dBm 1W/30 dBm 4W/36 dBm 2W/33 dBm
(8W used)43 dBm/39 dBm
Mobile Min Power 20mW/13 dBm 3mW/5 dBm 1mW/30 dBm 1mW/0 dBm 1mW/0 dBm
Phase 2GSM900
Phase 1DCS1800
Phase 2DCS1800 PCS1900
ARFCN range 1 to 124 0 to 124 and 512 to 885 512 to 885 512 to 810975 to 1023
Channel Spacing 200 kHz Bits per Burst 156.25
Modulation Type 0.3 GMSK Useful Bits per Burst 147
Modulation Data Rate 270.833 kHz Frame Period 4.62s
Tx/Rx Time Spacing Three Timeslots Timeslot Period 576.9s
Slots per Frame 8 Bit Period 3.692s
General GSM Parameters
For more inform at ion on the GSM stand ar d, see th e list of relat ed liter atu re,
given in Section 12.
The following table is a summary of the GSM specifics:
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The HP ESG-D series signal generat ors ar e capable of genera ting 0.3 GMSK
signals requ ired for t he development and testin g of GSM commun ications
systems a nd t he components of these syst ems. 0.3 GMSK signa l generation is
achieved by using the HP E SG-D series signal generat or with t he inter nal I/Q
baseband generator (Options UN3 or UN4). The baseban d generat or also
provides signals tha t conform t o other commu nications standa rds su ch as
PHS, PDC, NADC, DECT and TETRA.
1. Turn t he signal generator on or press Preset (the green but ton on th e
lower left corner of the instr umen t).
2. Set th e desired RF outpu t frequency. The cur ren t RF output frequency is
always shown in the frequen cy ar ea of the display. Press t he Frequency front
pan el har dkey to chan ge the RF outpu t frequency. To enter a new value for
frequency, rotate t he front pa nel knob unt il the desired frequency is
displayed, use th e up an d down ar row keys, or ent er th e value using the
numer ic keypad and press the GHz, MHz, kHz, or Hz ter mina tor softkey.
For example, to set a n outpu t frequen cy of 880MHz:
Press Frequency.
Key in 880 using the numeric keypad.
Press the MHz softkey.
Many GSM users a re accustomed to thinking in term s of chann el (ARFCN)
numbers, rather than absolute frequency values. There are formulae which
can be used to convert ARFCNs t o the corr esponding absolut e frequency
values. These form ulae a re given in Section 9.
3. Set th e desired RF output power level.
The curren t RF outpu t power level is always shown in the am plitude ar ea of
th e display. Press this front pa nel har dkey to cha nge the RF output power. To
enter a new value for amplitude, rotate t he front panel knob until the desired
am plitude is displayed, use the up a nd down arr ow keys, or enter t he value
using the num eric keypad an d press the dB m, dB uV, dBu Vem f, mV, uV,
mVemfor uVemfterm inat or softkey.For example , to set u p an output power level of 0 dBm:
Press the Amplitude hardkey
Press 0 on the num eric keypad
Press the dBm softkey
4. Press the front panel Mode key.
Pressing the grey front pan el Mode key reveals a menu of softkeys. These
softkeys a llow furt her menu s to be a ccessed, for configur ing th e desired digi-
tal communications standards, in this case GS M.
5. P ress the GS M softkey.
Pr essing this softkey reveals a men u of softkeys for genera ting fram ed or
unframed GSM tr ansmissions.
6. Data Format Pattern Framed
Pr ess t his softkey to toggle between Data Format Pattern , to tra nsmit a
continuous stream or pa ttern of data, and Data Format Framed , to tra ns-
mit a pulsed RF GMSK signal in a GSM TDMA format .
Select Data Format Framed
3. Gen erati ng a 0.3 GMSK
modulated burst s ignal
for GSM (DCS 1800 & PCS
1900) using the HP ESG-Dseries s ignal generator
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The lower ha lf of the signal genera tor's display will now show a gr aph ic of the
GSM timeslot pat tern , as shown in the diagra m below.
The default sett ing of the signal generator is th at it tra nsmits a single frame
of data (Frame Repeat Single softkey). The HP E SG-D can also be set to
transmit frames of data continuously (Frame Repeat Cont softkey) .
The data sequences that can tra nsmitted ar e described in Section 4
"Data Generat ion".
7. Man ipulating the timeslot
The HP ESG-D series signal generat or allows the contents of each timeslot to
be defined.
Pressing the Configure Timeslot softkey revea ls a men u of choices for
configur ing th e timeslot. This softkey is inactive unt il Data Format Framed
is selected.
In t his menu , the user can select which timeslots to turn on and choose the
type of RF power burst desired. The subsequent m enus ar e then used to
configur e the dat a an d tra ining sequence fields.
As mentioned in the int roduction, th ere ar e 156.25 bits in each timeslot. The
HP ESG-D optional baseband generat or (option UN3/UN4) implement s th e
GSM scheme by ma king every four th timeslot (i.e. timeslot 0 & timeslot 4)
157 bit per iods long , and t he r emainin g timeslots in t he fram e (i.e. timeslots
1,2,3,5,6 & 7) 156 bit periods long. This implementation complies with the
ETSI GSM standard (GSM 05.10, version 4.9.0, section 5.7).
A similar implementation applies to Guard Time and Extended Guard Time
bits. Gua rd time (G) appear s in the visual represen ta tion of th e timeslot as a
8.25 bit field. In th e actual implement ation, the guar d time in timeslots 0 & 4
ar e 9 bits long, and th e rema ining timeslots contain 8 bit fields. Extended
Guard Time (EG ) appears in th e visual represen tat ion of Access timeslots as
a 68.25 bit field. In th e actual implement at ion, the gua rd t ime in timeslots
0&4 are 69 bits long, and th e rem aining t imeslots contain 68 bit fields (also
docum ent ed in th e GSM sta nda rd "GSM 05.10, version 4.9.0, Section 5.7").
1. Turning Timeslots Off and On
After t he Configure Timeslot softkey has been pr essed, press the
Timeslot # softkey. Any one of th e eight t imeslots can be selected by
using th e front pa nel knob, the u p and down ar row keys, by enter ing
the nu mber using the nu meric keypad, and pr essing the Enter
ter mina tor softkey. The selected t imeslot is activated by toggling
Times lot Off On to On . The visua l represen tat ion of the timeslot
pat tern should now show the selected timeslot tur ned on.
Figure 8 .
ESG-D GSM Timeslot Patte rn
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2. Settin g the Timeslot type
Having selected t he a ctive timeslots, the t imeslot t ype can be set for
th e active timeslot. Any of the 8 t imeslots can be set t o one of the
following types:
Normal A normal burst is the most common burst in the GSM system an d
is tra nsmitted in one timeslot either from the base st ation or t he
mobile sta tion. This burst type configur es the t imeslot a s a t ra ffic
chann el. To select this bu rst type for t he a ctive timeslot:
Press the Normal softkey.
The following figure s hows an example of display graph ics for a n ormal t imes-
lot. This sh ows each field of the timeslot as it is defined by the GSM sta ndar d.
Frequen cy Corr ection
Timing is a critical need in a GSM system. The base st at ion ha s to provide
th e mean s for a m obile station to synchr onize with th e mast er frequency of
th e system. To achieve synchronization th e base stat ion tr an smits a
frequency correction burst , during certain kn own int ervals. Thisfrequency correction bu rst is simply a fixed sequence of zeros for th e dur at ion
of one timeslot. In a GSM network, frequency corr ection bur sts occur every 10
fram es (Fr am e 0, Fr am e 10, Fr am e 20 etc. of a BCH signaling data mu lti-
fram e (see the FCH in F igure 3), and always occur in timeslot 0 (the base
sta tion always genera tes the BCH on t imeslot 0). To ma ximize th e flexibility
of the HP ESG-D series signal genera tor, however, any timeslot may be set to
th e frequency corr ection t ype. Also note t hat th e frequency corr ection burst
will be repeat ed every fra me, not every 10 fra mes, if the bu ilt-in da ta genera-
tor is u sed. To repeat every 10 fra mes, a long user-defined dat a sequ ence
could be genera ted an d loaded directly into the signal genera tor's patt ern
RAM (see Section 4.4 "Generating long data sequences").
To select t his bur st t ype for th e active timeslot:
Press the FCorr softkey.
Synchroniza t ion
The base sta tion sends signals on the BCH which contain some valuable
system pa ra meter s, such as those which ena ble the mobile to synchronize to
th e BS. The mobile, however, needs a defined t ra ining sequence before it can
demodulate a nd decode this informat ion. The base st at ion t ells the mobile
which tr aining sequence to use with th e synchronization burst . The
synchronization bur st ha s an extended mida mble (or tra ining sequence) with
a fixed sequence in order to give the mobile the "key" it needs to decode the
system par am eters. Like frequency correction chan nels, synchr onizat ion
chann els occur every 10 fram es (Fram e 1, Fr am e 11, Fr am e 21 etc. of a
signaling data m ultifram e - see the SCH in Figure 3), and t he bursts always
Figure 9 .
ESG-D GSM Norm al
Timeslot
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occur in timeslot 0 . To maximize the flexibility of the HP ESG-D series signal
generat or, however, any timeslot m ay be set to the synchronization type. The
synchronization burs t will be repeated every frame, not every 10 frames, if
the built-in data generat or is used. To repeat every 10 fra mes, a long data
sequence could be genera ted an d loaded directly int o th e signal genera tor'spattern RAM (see Section 4.4).
To select t his bur st t ype for t he a ctive timeslot:
Press the Sync softkey.
Random Access
Mobiles us e a random access burs t when tr ying to gain initial access to the
system. This burst t ype is shorter th an a normal burst, and is used by the
base sta tion to measur e the tim e delay a mobile's burs t is experiencing.
To select t his bur st t ype for t he a ctive timeslot:
Press the Access softkey.
Dummy
In th e GSM system, the base stat ion mu st tr ansmit something in each times-
lot of the base channel. Even if these timeslots ar e not allocat ed to comm uni-
cation with an y mobiles, the base sta tion has to tra nsm it predefined dummy
bursts , specially defined for th is pur pose, in th e idle timeslots of the base
channel.
To select t his bur st t ype for t he a ctive timeslot:
Press the D ummy softkey.
Custom
The custom t imeslot is pr ovided for u sers' flexibility, but it is not a sta ndar d
GSM timeslot type. A cust om timeslot is configur ed using a n in tern ally-gener-
ated da ta pat tern , a downloaded sequen ce of bits st ored in a us er file, or by
supplying external dat a.
To select t his bur st t ype for t he a ctive timeslot:
Press the Custom softkey.
Once the desired t imeslot t ype has been selected, th e "Configure Timeslot"
menu will be displayed.
3. Configuring selected timeslot
The data and t ra ining sequence fields within a cert ain timeslot type may be
configur ed by the user. From within th e Configure Timeslot menu , select
the Configure ... softkey corresponding to the chosen timeslot type. For
example, to configure a norma l timeslot, the Configure Normal softkey
should be selected. The visual r epresent ation of the timeslot shows each field
of th e timeslot as it is defined by the GSM standa rd. Note tha t if the text in a
field is grey, the value in t his field cann ot be alter ed. However, if the t ext in a
field is black, the values in t his field can be changed. For example, in a
Norma l timeslot the data (E field - signifying encrypt ion bits), Stealing Flag(S) bits and t he tra ining sequence (TS ) values can be chan ged, but t he T
(Tail ) bits, and th e Guard (G) bits cann ot be altered. The fields th at can be
changed depend on the t ype of timeslot chosen. Note th at the FCorr timeslot
values can not be altered at a ll.
Selecting values for data
For Normal , Sync and Access Timeslots: Pressing th e E softkey from within
the Configure ... menu reveals a menu of choices for int erna l data genera-
tion (P N9, PN15, or a f ixed sequence of data) or t he u ser can choose to
supply his own dat a. The num ber of dat a bits in th e E field depends on th e
timeslot type chosen.
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For Custom Timeslots: The sam e choices as above are au tomat ically
displayed when th e Configure Custom softkey is pr essed.
The choices a vailable for dat a a re described in S ection 4.
The dat a values will be shown on the signal generat or's display,
below the gra phic of the curr ent t imeslot.
Sett ing values for the stea l ing bi ts
The st ealing bits ar e set t o indicate th e difference between speech
and cont rol data on a TCH. The S bits can t herefore only be set for
Normal timeslots.
Press the S softkey, and enter a '0' or '1' using the front panel kn ob, up
and down arr ow keys, or the num eric keypad, and press t he Enter
term inat or softkey.
Sett ing values for the tra ining sequence
The training sequence can be changed for the following timeslot typesonly: Normal , Sync and D ummy.
Press the TS softkey to change the 26-bit (64-bit for Sync) training
sequence. The preset hexadecimal value (when n ormal pr eset is selected)
for TS repr esents a color code according to the GSM st an dar d. A new
value ma y be entered, to simulat e different bas e sta tion codes, by
pressing this softkey.
The new value may be enter ed by using the front pa nel knob, up an d
down ar row keys, or th e num eric keypad and t he A,B ,C,D ,E , and F soft
keys, and pressing the Enter term inat or softkey. Note th at other color
code values us ed in GSM ar e specified in th e Help text .
Sett ing values for the Synchronization Sequence
The synchronization sequence can be alter ed for Access timeslot types
only. The synchronizat ion sequen ce has a s imilar function to the tr aining
sequence in other timeslot types .
Press the SS softkey t o chan ge the 41-bit synchronization sequence.
The preset hexadecimal value (when n ormal pr eset is selected) for SS
reflects t he GSM stan dar d, however a new value can be entered by
pressing th is softkey. A new value ma y be entered u sing the front pa nel
knob, up an d down ar row keys, or t he nu mer ic keypad an d the
A,B ,C,D ,E , and F softkeys, and press ing the Enter term inat or softkey.
Settin g values for Extende d Tail Bits
The extended t ail bits can be chan ged for Access tim eslot types only.
Press the ET softkey t o chan ge the 8-bit extended ta il bit sequence.
The preset hexadecimal value (when n ormal pr eset is selected) for E T
(extended t ail bits) reflects t he GSM stan dar d, however a new value may
be enter ed by pressing this softkey. A new value ma y be entered u sing
the front pa nel knob, up an d down ar row keys, or th e num eric keypad
and t he A,B,C,D,E, an d F softkeys, and press ing the En ter t erm inat or
softkey.
8. Retur n to the top level menu by pressing the Return front panel har dkey
twice.
9. The RF car rier is modulated only when Mod On/Offis set to On . To tu rn
GMSK modulation on, set GSM Off On to On .
10. Set RF On Off front panel har dkey to On . This makes th e GSM signal
available at the RF OUTPU T connector.
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The HP E SG-D series signal generat or offers a var iety of int erna lly generat ed
data patt erns (PN9, PN15, fixed 4-bit repeatin g sequences, set pat ter ns of
ones an d zeroes,) or you can choose to supply your own da ta (download a
binary file or input dat a u sing th e DATA INPUT connector). It is a lso possible
to continuously repeat th e chosen data pattern .
With H P E SG-D series signal generat ors equipped with Options UN3 or UN4,
the ba seband gener at or's clock can be intern ally or exter nally supplied, and
the external data clock can be set to a normal bit clock or a symbol clock for
the NADC, PHS, PDC an d TETRA format s. There a re severa l data /clock
combinat ions a vailable to the u ser a nd t he selections will affect t he input s
required and the outputs available.
For m ore informa tion on th e input an d output r equirements for da ta and
clock settin gs, see Tables 7-1 an d 7-2 in Section 7 "Operat ion" of th e HP E SG
User Guide.
4.1 Choosing Data Patterns
Th e Data softkey is available in th e GSM menu to select a da ta pa tter n for
unframed tr ansmission (Data Format Pattern is selected). The Data soft-
key is inactivat ed when Data Format Framed is selected for fram ed tra ns-
missions. If data genera tion for fra med tr ans missions is requir ed, the same
choices ar e available by pressing t he E softk ey, wit hin th e Configure
Timeslot Normal, Configure Timeslot Syn c , Configure Timeslot
Access menus, and from th e Configure Timeslot Custom menu, as
ment ioned in t he pr evious section.
P N9
Press the P N9 softkey to select t he P N9 pseudoran dom bit sequence. The
PN 9 sequence consists of 511 bits (29 1 bits) and complies with t he CCCIT
Recommendation 0.153 .
PN15
Press the PN15 softkey to select t he P N15 pseudoran dom bit sequence. The
PN 15 sequence consists of 32767 bits (215 1 bits) and complies with CCCIT
Recommendation 0.151.
Fixed 4 bit
Press the FIX4 softkey to select a 4-bit repea ting sequence . Ent er th e
desired 4-bit pat ter n using th e front pa nel knob, up an d down ar row keys, or
enter th e value using the nu meric keypad and press th e Enter terminator
softkey.
Other Patterns
Press the Other Patterns softkey to select da ta pat tern s of 1's and 0's. Data
pat ter ns of 4 1's followed by 4 0's, 8 1's followed by 8 0's , and so on, may bechosen.
External Data
Press the Ext softkey in the da ta s election menu (or in the E m enu for fra med
tr ans missions) to select extern al data . With Ex t selected, the dat a signal
should be supplied to the DATA INPUT connector.
The DATA connector expects a TTL signa l where a TTL high is a data 1 an d a
TTL low is equivalent to a dat a 0. The ma ximum da ta ra te is 1.152 Mbit/s.
The appr opriate dat a a nd symbol clocks must also be supplied to the front
pan el inpu ts DATA CLOCK an d SYMBOL SYNC.
4. Data Gen eration
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User Files
The HP ESG ser ies signal generat or allows user-specified data sequences to
be loaded int o the n on-volatile mem ory of the s ignal genera tor.
These dat a sequ ences, accessible through t he file cat alog featu re of the signal
generat or, ar e comm only used to:
insert a specific set of data into the data field of a tim eslot(s) of a built-in
commun ications st andar d.
simulat e some type of tr an smission between a base st at ion an d a mobile by
specifying the da ta of th e entire fra me.
Press the User File softkey t o display th e cata log of binary files stored in th e
signal generator's memory. A custom file may be selected from this catalog for
the u ser-specified data pa tt ern. Scroll thr ough the listed files until the
desired selection is highlighted, th en press the Select File softkey.
If you elect to supply your own da ta file for fram ed tr ans missions, it sh ould be
created t o exactly fill the da ta fields of an integer n um ber of timeslots (n*148
bits for a GSM Custom tim eslot a nd n*114 bits for a GSM Norma l timeslot .
The following diagram illust ra tes t hat different u ser files may be selected t o
fill the da ta fields of different timeslots. In t his exam ple, UserFile #1 is
selected t o fill cust om timeslot #0. The first 148 bits of data fill the da ta field
of the timeslot in Fr am e 1. The next 148 bits go on t o fill timeslot #0 in F ra me
2, Frame 3, and so on. A second userfile, UserFile #2, is selected to fill times-
lot #5, an d is also sequent ially loaded into timeslot #5 of every fram e un til the
end of th e file.
If the end of the file does not coincide with th e end of a fra me, dat a will be
truncated in one of the following ways:
1. Enough fram es will be generated to tran smit as mu ch of the data pattern
as will fit into complete fram es. The rema ining bits of th e data pat ter n (which
ar e too few to completely fill a fram e) are t ru ncated.
2. If two files of unequa l sizes are selected for different timeslots of the sam e
framed tr ansmission, enough fram es will be generat ed to tra nsmit a s mu ch of
the da ta pat tern of the lar gest file as will fit into complete fram es.
The rema ining bits of the da ta pa tt ern a re tr uncat ed. The smaller file will be
UserFile #1 UserFile #2
Frame #1 Frame #2 Frame #3.....
.....
.....
.....
.....
.....0 1 2 3 4 5 6 7 0 1 2 3 4 5 6 7 0 1 2 3 etc.
................
................
................
148 bits
148 bits
148 bits
................
................
................
148 bits
148 bits
148 bits
Figure 10
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repeat ed as ma ny times as n ecessar y to completely fill these frames. Data will
be tru ncated for t he sm aller file to coincide with t he end of the last frame.
3. If a user 's file and a PN9 file are selected for different timeslots of the sa me
framed tra nsmission a nd th e user's file is shorter t han the P N9, 511 frames will
be generat ed to transm it the P N9 without t run cation. The end of the PN9 datawill coincide with the end of the 511th frame. The sma ller user 's file will be
repeat ed as ma ny times as n ecessar y to completely fill these 511 fra mes. Data
will be tru ncated for th e sma ller file to coincide with th e end of the last frame.
4. If a user's file and a PN9 file are selected for th e same fram ed tra nsm ission
and t he user 's file is longer th an t he PN9, enough frames will be generat ed to
tra nsmit a s much of the data pattern as will fit into complete frames.
The rem aining bits of the da ta patt ern (which ar e too few to completely fill a
frame) are tr uncated. The PN9 data will be repeated as ma ny times as neces-
sar y to completely fill these fram es, but th e PN9 sequen ce will be tru ncated if
necessary.
The following SCPI comm and downloads a da ta sequence into the HP ESG
series signal generator:
MMEM: DATA "FILEN AME", #ABC
where,
A = The num ber of numer ic digits in B, which specifies the a mount of dat a in C
B = The num ber of bytes of dat a in C
C = The dat a
For exam ple, to download a file, called "NEWDATAFI LE", with da ta bytes in
ASCII, the comman d :
MMEM: DATA "NE WDATAFILE", #1912SA4D7 89
gives the A, B and C fields the following meanings:
A = the number 1 ; specifies th at B conta ins a single digit.
B = the number 9 ; specifies tha t C contains 9 bytes of dat a.C = 12SA4D789 ; the ASCII represent at ion of th e data t ha t is downloaded to
the HP ESG.
In t he following examp le, th e file "NE WDATAFILE1", cont ain s 2 bytes of
ASCII data:
MMEM: DATA "NE WDATAFILE1", #2101 2&A%4D 789
gives the A, B and C fields the following meanings:
A = the number 2 ; specifies tha t B contains a double digit - in t his case 10 .
B = the number 10 ; specifies that C contains 10 bytes (in ASCII) of data
C = 12&A%4D 789 ; the ASCII repr esenta tion of the digita l demodulat ion dat a
tha t is downloaded to th e HP E SG.
If the dat a is downloaded usin g ASCII char acters (which represent one byte of
data per char acter), 19 bytes (152 bits) of data mus t be ent ered for Cus tom
timeslots in order tha t th e corr ect ASCII cha ra cter is form ed. Because th e
GSM cust om timeslot only really needs 148 bits of data, when t he HP ESG
loads t he us er file int o the tim eslot, it will drop the four least-significant bits of
the data sequence. A file of 18 bytes (represen ting 144 bits ) of data is too small
to completely fill the 148-bit d ata field. In t his case t he en tire file would be
tr uncat ed an d nothing would be modulated. By the s am e logic, 15 bytes
(120 bits) of data m ust be entered for a Norm al timeslot to complete th e fina l
ASCII char acter.
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The following SCPI comm an d can be used t o query a digita l demodulation
user file from t he file system :
MMEM:DATA? "fil enam e"
For example, using the comm and
MMEM:DATA? "NE WDATAFILE"
will retur n the dat a #1912SA4D789 in the sam e #ABC format a s used in the
earlier example.
The following exam ple progra m demonst ra tes how to genera te a pr ogra m to
send a file and da ta to the H P E SG-D signal generat or's Userfile directory.
This program example was creat ed in Rocky Mountain Basic version 6.0.
10 Sig_gen=719
20 LOCAL Sig_gen
30 CLEAR Sig_gen
40 CLEAR SCREEN
50 OUTP UT Sig_gen;"*RST"
60 OUTP UT Sig_gen;"MMEM:DATA ""Newda ta file"",#1912SA4D789"
70 END
Exam ple programs showing how to apply basic SCPI concepts , ar e given in
Chapt er 7 "Opera tion "Userfile Applicat ions"" of th e HP ESG User Gu ide.
Once the file ha s been tra nsferr ed to the HP ESG series signal generat or,
existing an d newly-tr ans ferred files can be reviewed using the signal genera -
tor's memory cat alog.
1. P ress the Util ity butt on located under MENUS .
Note: Press the Local button to place the instrument in the local mode.
2. Now pr ess Memory Catalog
3. P ress (All ) to review all the files in th e system.
4. Now press Binar y to review th e binar y files tha t exist.
To generat e a GSM t ra ffic multiframe, one would need t o genera te bit
sequences for ea ch timeslot of the mult ifra me, download them to user
files, then select the custom bur st m ode in GSM a nd ident ify which
user file to insert in each tim eslot. The length of each timeslot file
would have t o be :
148 bits x 26 frames = 3848 bits = 481 bytes
where,
148 = the nu mber of dat a bits in a GSM Cust om timeslot
(the other bits are gua rd tim e and do not need to be loaded) and ,26 = the num ber of frames in a t ra ffic mu ltiframe
The 3848 bits would be sequent ially loaded in the selected timeslot thr ough
the 26 frames.
To simulat e a contr ol mu ltiframe, such as a BCH, a user file containing:
148 bits x 51 fram es = 7548 bits = 944 bytes
where,
148 = the nu mber of data bits in a GSM Cust om timeslot
(the oth er bits ar e guard tim e and do not need to be loaded) an d,
51 = the num ber of frames in a signaling mult ifra me
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could be downloaded int o timeslot #0 of the GSM fram e. The actua l data in
the u serfile would have to represen t th e appropriat e inform at ion for a BCH
(i.e. the da ta sequence corresponding to a FCH in fra mes 0, 10, 20 ; SCH in
frames 1, 11, 21 ; and so on). Remember t hat th e BCH tran smits its u seful
inform at ion always in tim eslot #0 - dumm y data or, for example, user filesrepr esenting a TCH, could be selected for one or all of the other timeslots.
The size of userfile that may be downloaded depends on the a vailable memory
of the signa l generat or's file system . Curr ently, the ma ximum a mount of space
available in th e file system is about 128 kbytes. The mem ory available for
dat a files also shrinks if memory is also used for sa ved inst ru ment sta tes or
sweep list files. There is enough mem ory in t he file system t o genera te m any
multifram es using userfiles, but there a re constra ints on th e num ber of user-
files tha n can be downloaded t o Cust om timeslots in order to generat e a GSM
superframe.
A GSM superfram e conta ins 51 * 26 fra mes = 1326 fram es. Therefore for an y
par ticular t imeslot, a GSM Cust om file would requir e:
1326 * 148 bits = 196248 bits of informat ion for th at timeslot.
This requires a 25 kbtye user file. Remember t hat the m aximum am ount of
memory available in t he file system is 128 kbytes ,so only a m aximum of 5 of
these userfiles could be stored in th e file system.
Now, consider how much space 1326 GSM fra mes t ake u p in dat a genera tor
memory.
1326 * 156.25 bits/tim eslot * 8 timeslots per fr am e = 1.6575 Mbits
When dat a is writt en to RAM, 1 bit of data r equires 1byte of pat tern RAM,
ther efore a GSM super fram e would requir e 1.6575 Mbytes of RAM.
Option UN3 cont ains 1MBytes of dat a genera tor memory (or pat tern RAM)
wherea s Option UN4 offers 8MBytes. Only Option UN4 can th erefore be used
to generate th e data pa ttern used to create a GSM superfram e. This may be
achieved by car rying out a "direct write" of data to the da ta generat or
memory. Details on how to car ry out t his direct writ e of dat a a re given in
Section 4.4.
4.2 Single /Continuou s Data patterns
A choice of wheth er t o outpu t just one occur rence of the selected dat a, or t o
output a continuous stream of the data pattern is available.
Fr om the first-level GSM menu , set the Pattern Repeat Single Cont to
Pattern Repeat Single an d the signal genera tor will output a single occur -
rence of the chosen dat a. Note that Exter nal dat a cann ot be selected when
Pattern Repeat is set to Single . Select the tr igger event for t he output using
the Pattern Trigger softkey. This softkey r eveals a men u of choices for tr ig-gering an unframeddata pattern . The data can be triggered by the front
panel Trigger key, by an exter nal t rigger supplied to th e PATTERN TRIG-
GER rea r pa nel connector, or by a comm and sent over H P-IB.
The Pat tern Trigger softkey is inactive when Data Format Pattern Framed
is set to Framed. To trigger a one-shot pattern the tr igger must m ake a t ran -
sition from low to high, an d is sa mpled by th e rising edge of the da ta clock.
The HP E SG-D also has the capability of tr ans mitt ing fra med dat a cont inu-
ously or output ting a single fra me. If only one t imeslot is on, selecting a single
framed t ra nsm ission (Fra me Repeat S ingle) will outpu t t he following
sequences:
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4-Bit Pattern s (FIX4) - A single fram e is genera ted. The 4-bit
patt ern r epeats u ntil the dat a fields are completely filled.
Each trigger tra nsmits the same frame.
P N9 - A single fra me is genera ted. The da ta fields ar e filled with
the leading bits of the PN9 sequen ce. A tr igger causes t he fram e tobe tran smitt ed. The dat a fields of this fra me ar e then filled
sequent ially with th e next series of PN9 dat a bits. A tr igger causes
the fram e to be tra nsmitted. This process continues, tran smitting the
entir e PN9 sequence fra me by fra me. The last bit of the P N9
sequence in a data field is immediately followed by the first bit of a
second PN9 sequence.
P N 15 - A single fra me is genera ted. The da ta fields ar e filled with
the leading bits of the PN15 sequen ce. A tr igger causes t he
frame to be tr an smitt ed. The dat a fields of th is
frame ar e then filled
sequent ially with th e next series of PN15 data bits. A tr igger causes
the fram e to be tra nsmitted. This process continues, tran smitting the
entir e PN15 sequence frame by fram e. The bit of the PN15 sequence
in a data field is immediately followed by the first bit of a second
PN15 sequen ce.
User Fi le - The user's file should have th e appr opriate dat a t o fill
an int eger num ber of times lots. If not, the rem aining bits are
tr uncat ed. Depending on the size of th e file, more th an one
frame can possibly be genera ted.
External Data - Extern al dat a is clocked into the da ta fields of
the t imeslot. A single frame is genera ted.
Triggering sin gle fra mes of data is described in Section 5.
To output a contin uous str eam of data, Frame Repeat Single must be
toggled to Frame Repeat Cont . Selecting Cont with fram ed data causes the
frames t o be tra nsm itted cont inuously.
Note:
As with Section 1, th e top level GSM softkey menu m ust be retur ned to,
and GSM On must be turn ed set and RF tur ned on.
4.3 Data Dependen cies
There ar e some situa tions where certa in combinat ions of dat a pat tern s will
cause the da ta t o be tru ncated or discontin uous. A discontinuous pat ter n will
mak e BER test ing invalid, ther efore, it is very import an t t o be awar e of these
situations.
Any combination of external data and a PN15 data pattern will cause a
discontinuous P N15 patt ern.
Any combinat ion of user 's files and a P N15 data pa tter n will cause a
discontinuous P N15 patt ern.
4.4 Generating long data patte rns, such as a GSM supe rframe.
The HP E SG-D signal generat or (with Option UN3/UN4) offers the user t he
capability to generate long data patterns, and store them in the signal gener-
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ator's pattern RAM.
The length of data sequence that can be stored in the pat ter n RAM depends
on the insta lled optional baseban d genera tor. Option UN3 pr ovides 1MB of
RAM and Opt ion UN4 offers 8MB. This tr an slates t o maximum lengths of
data sequences of 1Mbits a nd 8Mbits r espectively, becaus e each bit of data
requires 1Byte of RAM. This is becau se ther e are other par am eters, such as
whether RF power is to be switched on, that mus t be set for each bit of data .
This met hod of dat a gener at ion r esults in a flexible means of contr olling
every single data bit in a user-defined sequence.
The SCP I comm an d MEM:DATA:PRAM: BLOCK #0 < dat a_block >
(or MEM:DATA:PRAM: LIS T < uin t8 ,...,...> )
allows a block of ASCII da ta or a str ing of decima l values t o be written
directly to the dat a genera tor memory (patt ern RAM). This data t akes over
the bur st contr ol of the m odulating signal. The entire dat a genera tor memory
is cont rolled by th is comma nd. In other words, th e user is in cont rol of how
the m odulation is implemented. The featur es of the bu ilt-in comm unications
form at s, such as t imeslots a nd t imeslot t ypes, can no longer be u sed. To car ry
out a direct load of dat a int o the pat tern RAM, the desired comm unications
mode must be selected in order to set up the baseband generator a nd dat a
generat or clock r at es for t ha t m ode. For exam ple, if GSM tra nsm ission is
required, press Mode , GS M, GSM On , to set the clock rat e for GSM tr ans -
mission. This will ensure the dat a is tr ansmitt ed at t he correct ra te.
Note that when th e front pan el or SCPI u ser inter face of a mode resum es its
norma l opera tion, the user int erface is ta king back the contr ol of th e data
generat or m emory. This means t hat all previous user data written to the
patt ern RAM by the above comman d will be erased.
As mentioned ear lier, one byte of data is used for every data bit produced.
The pur pose of th ese bits is as follows :
Bit Pos ition Bit Valu e (in de cimal) UN3/UN4 valu e0 1 data value
1 2 0 a lways
2 4 burst cont rol
3 8 0 a lways
4 16 must always be set to 1
5 32 0 a lways
6 64 Event 1 cont rol
7 128 Pat tern Reset
Bit 0 ("data value") should be set to a 0 or 1 as requ ired for a da ta bit.
Bit 2 ("burs t cont rol") should be set t o a 0 for bur st off or 1 for bur st on.
All data values tha t requires bursted RF power out must have this bit on.
The "Event 1 cont rol" bit (Bit 6) should be set to a 0 or 1, as desired , to be
output a t th e EVENT 1 rea r pan el connector. "Pattern Reset" should be set to a 1 to reset the patt ern generation to the
star t, after t his entry is pr ocessed.
The user, ther efore, has complete contr ol over t he value of dat a bits t ra nsm it-
ted, wheth er RF power bur st is on, how long th e burs t will be on for, and
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where to reset the patter n.
For example, to store a da ta value of 1, with burst contr ol on, the decimal
value of th e dat a would be 21.
To send a fixed 4 bit repeat ing sequence of 1100, with bur st on, th e value th e
comm and ma y look like th is:
MEM:DATA:PRAM:LIST 21,21,20,148
Each "block" represents the dat a bit an d all it 's parameters, and takes up
1Byte of RAM. Note th at t he last value in t he sequence, 148, sets t he Pat tern
Reset bit, so tha t th e data counters for the mem ory will reset a t th e beginning
of the 1100 sequence.As mentioned in Section 4.2, the da ta bits corr esponding to the 1326 frames
in a super frame could be genera ted an d loaded into the pat ter n RAM. There
ar e 1250 bits in a GSM fra me an d ther efore a su perfram e contains 1.6575
Mbits. This would require 1.6575MB of RAM, when using the direct load
meth od. In order t o have sufficient mem ory for generat ing a GSM superfram e,
Option UN4 (which has 8MB of pat tern RAM) must be inst alled. Unlike the
custom file method, all the bits in t he su perfram e mus t be specified - this
includes gua rd bits, cont rol bits a nd da ta bits. To genera te a continuous
super frame t he Pat ter n Reset bit should be set for th e last bit in the sequence,
so that t he data generat ion will star t again at the first bit of the superframe.
Bit Position
Setting
Bit Value
= 21 !
16 + 4 + 1
Event 1 Burst Data
7 6 5 4 3 2 1 0
0 0 0 1 0 1 0 1
always"1"
Figure 11.
Sett ing data values
1 Byte 1 Byte 1 Byte 1 Byte
"1" "1" "0" "0"
Pattern Reset Bit
was set to '1'
0 0 0 1 0 1 0 1 0 0 0 1 0 1 0 1 0 0 0 0 0 1 0 0 1 0 0 1 0 1 0 0
21 21 20 148 etc.
Pattern Reset Bit
Figure 12.
Blocks of data
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There a re several options available to the user to trigger a single GSM frame.
These ar e using th e Trigger key, triggering over th e bus, and t riggering the
frame externa lly.
Fr om the GSM mode:
Select Data Format Framed .Toggle Frame Repeat Single Cont to Frame Repeat Single .
Press the Frame Trigger softkey t o display the ra nge of options:
Trigger Key - Press the front panel Trigger hardkey to output one frame of dat a
Bus - Pr ess this softkey to tr igger th e single fram e over HP-IB
External - Pr ess this softkey to trigger a single fra me from an externa l
source. The fram e triggerpulse mu st be sent t o th e PATTERN
TRIG IN rea r pa nel BNC input connector. The HP ESG-D is
tr iggered when t he CMOS input tr ans itions from low to high,
then one frame of data is generated. The minimum trigger input
pulse width , high to low, is 100ns. The trigger edge is latched
and sampled by falling edge of data bit clock to synchronize
tr igger with bit t iming. At the end of the fra me, guard bits a re
generat ed unt il a new tr igger is received . If the tr igger
ar rives t oo ear ly (1.5 to 2.5 bit clock periods before th e end of a
frame), it will be ignored an d the n ext frame is delayed unt il the
next valid tr igger occurs. If th e tr igger occurs too lat e (between
N-1.5 to N-2.5 bit clocks a fter t he fra me ends ), then t he fram e
begins N bit clocks a fter t he pr evious frame ends. For exam ple ,
if the trigger occurs between 0.5 and 1.5 bit clock periods after
the fra me ends, i.e. N=1, then 1 add itiona l bit is inserted in
between frames (i.e. next frame begins 1 bit clock period after
previous fra me ends). For m ore inform at ion on fram e and
pat tern tr igger tim ing, see Section 7 of the E SG User Gu ide.
An applicat ion for th e externa l fra me tr igger featur e is in GSM Base Sta tion
manufacture. The BTS transmits its timing information on the downlink BCH,
including deta ils of the fra me t iming. The BCH is used t o comman d th e mobileand t ell it when to respond and sta rt commun icat ion with th e BTS. In Base
Sta tion testing, the HP ESG-D signa l genera tor (configured with th e optional
IQ baseband gener at or) can be used simulat e a mobile in order t o send a signa l
to the BTS t o verify correct BTS operation. The HP ESG-D must ther efore be
capable of sta rt ing its tr an smission at th e correct time relative to the BTS
tr ans mission, as would a 'real' mobile station. To achieve this, the HP ESG-D
can be configur ed to accept a frame tr igger (sett ing Frame Trigger External
and supplying BTS fra me clock to PATTERN TRIG IN r ear pan el connector)
from t he BTS, as sh own in the following diagram . This synchronizes the
HP ESG-D to the BTS.
BTS
Tx BTS
Rx
Frame Clock
Combiner
Pattern Trig In
RF OUTPUT
HP ESG-D
Figure 13.
Applicat ion of exte rnal
frame trigger
5. Trigge ring a
GSM Fram e
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If the BTS sends a t rigger at the sta rt of every fram e, and the HP ESG-D is
set up with an y of th e intern al data selections (PN9, PN15, FIX4, Other
Pat ter ns) , the ESG-D will send a fra me of th e chosen data every time it
receives the t rigger. Some Base St at ion t ests, however, may r equire a st rea m
of frames from the H P E SG-D to synchronize to a single trigger from th e BTS.In t his case, a us er file conta ining the appr opriate nu mber of bits for th e
num ber of fram es needed in the strea m could be used.
Settin g a trigger delay
A program ma ble delay, in bits, may be set in order to trigger the H P ES G-D
in a different timeslot. This featu re is only available when t riggering the
signal genera tor exter nally. The Tr igger Delay r esolut ion is one data bit clock
period.
To set t he extern al tr igger delay:
From the Frame Trigger men u, a s descr ibed above, select exter na l triggering:
Select th e Ex t softkey.
Se t Ext De lay Off On to On
Press the Ext Delay Bits softkey
Ent er th e desired delay using the front panel knob, up an d down
arr ow keys, or the n umeric keypad, and press th e Enter terminator
softkey. The ma ximum pr ogra mm able delay is 65,535 bits. Note t ha t
sett ing the t rigger delay to the frame bit count m inus t wo will allow
the frame to sta rt within +/- one h alf bit clock of trigger edge.
For exam ple, the GSM Fr am e bit count is 1250, th erefore sett ing the
delay to 1248 will allow th e fram e to st ar t with in h alf a bit clock of
the t rigger.
To tr igger th e HP E SG-D series signal generat or to start producing
frames contin ually.
Fr om the GSM mode:
Select Data Format Framed .
Toggle Frame Repeat Single Cont to Frame Repeat Cont .
Press the Frame Trigger softkey t o choose between t riggering using t he
front panel Trigger key, or over
HP-IB (Bu s softkey).
Synchroniz ing equipment to the HP ESG-D series s ignal gene rator
The HP E SG-D series signal generat or may also be used to tr igger other
equipment.
Fr om the first level GSM menu , press the More (1 of 2) softkey.
Press the Sync Out softkey t o display the menu of choices for output ting a
1-bit synchronization signal to th e EVENT 1 r ear pan el connector.
Begin Frame synchronization signal occurs a t t he beginningof t he GSM frame.
Begin Timeslot # synchronization signal occurs a t t he beginning
of th e selected GSM t imeslot. Any one of the 8
timeslots ma y be selected.
Timeslot All synchronization signal occurs a t t he beginning
of the ea ch timeslot in t he GSM fram e
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It is also possible to move the synchr onizat ion signa l forwar d or back from t he
beginnin g of the fra me or t imeslot.
Fr om the GSM first level menu , press the More (1 of 2) softkey.
Press the Sync Out Offset to set the num ber of bits of offset.
Enter the desired value using the numer ic keypad, the up and downar row keys, or th e front pa nel knob and pr ess the Enter terminator
softkey. The range of allowed values is 155 through +155 bits
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The HP ESG-D series signal generat or (with option UN3 or UN 4) provides the
flexibility t o modify the commun icat ions form at s pr ovided. For th e GSM per son-
ality, the modulation dat a r ate, the burst shape an d the Gau ssian Filter Factor
can all be modified. Note that adjustin g these factors mea ns th at t he signal
generat ed will no longer be a st an dar d GSM signa l. The display annu nciator
will cha nge from GSM:STANDARD to GSM:MODIFIED when an y of the
aforementioned attributes a re a ltered.
1. P ress the Mode front pa nel har dkey.
2. P ress the GS M softkey.
3. P ress the More (1 of 3) softkey a t th e bottom of the display.
A menu containing t he softkey options an d Modify Stan dard will be
displayed.
4. To alter th e data r ate or the filter alpha, press Modify Standard .
4.1 To adjust t he filter factor, press th e Filter softkey.
The choice of filter factor r an ges from 0.2 to 0.7, in 0.05
increment s. To enter a new value for filter alpha , rotate th e front
panel kn ob unt il the desired value is displayed, use the up a nd
down ar row keys, or ent er th e value using the num eric keypad.
The display should n ow include a s ymbol in t he F ilter field, to
indicate that it differs from th e GSM standa rd.
4.2 To adjust th e modulation data rat e, press the Bit Rate softkey.
A dat a r ate with in the r ange 163 kbit/s to 300 kbit/s may be
selected. To enter a new value for th e modulation data ra te,
rotat e the front pan el knob unt il the desired value is displayed,
use the up an d down a rrow keys, or ent er th e value using the
numeric keypad and press the kbs softkey. The disp lay sh ould
now include a s ymbol in th e Bit Rat e field, to indicate th at it
differs from the GSM sta ndar d.
Th e Restore Defau lt Filter BbT and the Restore Default Bit Rate softkeys
set th e filter factor and m odulation dat a ra te to the GSM stand ar d values of 0.3
an d 270.833 kbit/s res pectively.
5. To alter t he GSM Burs t Shape, press Burst Shape .
Within t his men u, the r ise and fall times of th e GSM burst m ay be modified.
The rise a nd fall of the bur st can also be delayed from th e default values.
This is useful for doing mar gin testing an d adding impairm ents t o existing
systems, an d for t he development of new system s.
5.1 To adjust th e rise an d fall times, press the Rise Time and Fall
Time softk eys r espectively.
To enter a new value for t he rise/fall time, rotate th e front pa nel knob until
the desired value is displayed, use th e up an d down ar row keys, or ent er th e
value using the nu meric keypad and press th e Enter softkey. Rise an d fall
times can be set in bit periods, with in the limits 0.2 to 30 bits.
6. Customizin g the
GSM Mod e
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Here, the rise time ha s been decreased from t he stan dard value, meaning that
the power level is ra mped u p too quickly, and th e bur st profile does not fit
within t he desired m ask. This could cause inter ference with other mobiles in
the cell.
5.2 To delay the rise or fall of th e GSM bur st , press t he
Rise Delay and Fall Delay softkeys r espectively. Delay tim es of up
to 10 bit clock periods can be set. To enter a new value for th e delay
time, rotat e the front pan el knob unt il the desired value is displayed,
use the up an d down a rrow keys, or ent er th e value using the
numer ic keypad and press the Enter softkey.
Here, a rise delay has been added to the burst . As can be seen, the
burs t pr ofile is now right at the lower limit of the ma sk. Any furt her
delay would r esult in the output power level being rea ched too late,
and useful bits of information could be lost.
Th e Restore Default Burst Shape softkey restores the burst shape values
to the r ise/fall tim es of 4.22 and 3.44 bit clock per iods and ris e/fall delays of
zero an d 4.38 clock periods.
+1.0 dB
1.0 dB
+4 dB
6 dB
30 dB
70 dB
6 dB
30 dB
70 dB
147 "Useful" Bits
542.72s
148 "Active" Bits, 546.42s
3 57 1 26 1 57 3
10s 8s 10s 10s 10s8s
Power
Time
Figure 14.
Adjust ing the rise t ime of a
GSM TDMA Pow er Bu rst
+1.0 dB
1.0 dB
+4 dB
6 dB
30 dB
70 dB
6 dB
30 dB
70 dB
147 "Useful" Bits
542.72s
148 "Active" Bits, 546.42s
3 57 1 26 1 57 3
10s 8s 10s
Rise Delay
10s 10s8s
Power
Time
Figure 15.
Adding rise delay to a GSM
TDMA Pow er Burst
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7. Adjacen t Broadc ast
Channel Generat ion
usin g HP ESG-D series
s ignal generator and theHP 8922 GSM Tes t Se t.
The pur pose of this section is to demonstr at e how the HP ESG-D series signal
generat or can be used with the HP 8922M GSM Mobile Test Set t o generat e
an Adjacent Broadcast Channel.
The HP 8922 fam ily of GSM MS Test Set s ar e integrat ed test solutions for t he
production a nd ser vicing of GSM radios. The HP 8922 used in th is product
note is designed for m anu factur ing, providing accur at e and r epeata ble
measurem ents for consistent t est r esults. The HP 8922M test set generally
follows th e procedur es as outlined in th e associat ed GSM recomm endat ions,
but does not necessar ily meet t he exact requirem ents or cover all ran ges,
limits or conditions requ ired for type appr oval t esting.
As mentioned in S ection 2, a ll Base St at ion Tr an sceivers (BTSs) continua lly
tr ans mit a Broadcast Cha nn el (BCH). The BCH is like a beacon - it allows
mobiles to find th e GSM net work. Th e BCH consists of var ious par ts for
frequency correction, synchronization, control and access. Its exact configura-
tion varies on the n um ber of user s expected in t he cell. The ARFCN u sed by
the BCH is different in each cell. The mobile ha s a list of these frequency
channels in the Base Allocation (BA) table, in order to know which BCH
frequencies to go out and measu re. The BA table is coded onto the BCH. The
BA ta ble will differ for GSM 900, DCS 1800 an d PCS 1900 system s. The BCH
is always received by all mobiles in a cell, wheth er t hey ar e on a call or not.
Ea ch m obile measur es th e power of the ser ving cell and t he a djacent cell's
BCH. Mobiles also measur e the st rengt h an d quality of the signa l being
received on the Traffic Channel. Measurements of Received Level (RxLev)
and Received Quality (RxQua l) are report ed back to the serving cell base
sta tion. RxQual r eport s can be ma pped onto bit-error r at io. The RxLev
num bers can be ma pped directly onto signal levels in dBm. As a m obile
roams a round, it continu ally measur es th ese power levels. If the mobile
moves far from t he se rving BTS, i.e. if th e RxLev becomes sufficient ly low on
th e ser ving cell, th e mobile will switch to an adja cent cell which is closer.
In th is section, two broadcast chan nels will be genera ted on different
ARFCNs, and sen t to a mobile, using the HP 8922M GSM Test Set a nd th eHP ESG-D series signal genera tor .The t wo BCHs will have different
Broadcast Colour Codes (BCCs) to allow the mobile to differentiate between
the HP 8922M BCH an d the H P E SG-D BCH.
A BCH at RF, corresponding to a certain ARFCN, will be sent to a mobile
using th e HP 8922M. Then BCH inform ation at ba seband will be generat ed
using th e 8922M GSM Test Set . This data will be modulated up to a
frequency corresponding to a different ARFCN u sing the HP ESG-D series
signal generat or and s ent t o the mobile. It will then be possible to verify tha t
the mobile can find both signals (or both BTSs).
There a re formulae given in Section 9 to convert ARFCNs int o absolute
frequency values. The deta ils for cell selection an d r eselection ar e given in
Chapter 20 of the GSM 11.10 Specifications.
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Connect t he HP 8922M MS Test Se t, the HP ESG-D Signal generator
and the mobi le under test
1. Connect th e HP 8922M, HP E SG-D an d the m obile to be tested, as
shown in Figure 16.
2. Power on th e HP 8922M, th e HP ESG-D series signa l generat or
and t he mobile.
Set up HP 8922M to send broadcast data to HP ESG-D signal gene rator
Th e H P 8922M has default sett ings to broadcast on frequen cy chann el ARFCN
20 with a n am plitude of -85dBm. Different sett ings for these par amet ers ma y
be chosen if desired, but this will n ot be covered in t his note. Remember th at
the in sert ion loss thr ough the power divider m ust be accounted for, as t his willaffect the a mplitude of the signal.
3. Fr om the front pan el, press the Cell Config hardkey.
4. Go to the BA (Base Allocat ion) Table. This is a t able th at is sent to
the mobile to let it know which BCH ARFCNs ar e active in its cell.
First of all position t he cur sor on th e "Activat ed" field, push t he k nob
and change to "Sett able". There ar e 124 possible cha nnels t hat can be
set. Position t he cursor t o the top left "0" an d push th e cursor contr ol
knob.
A channel may be selected by going to the corresponding
position in the ta ble, and s etting th e value to "1" .
For exam ple, to set chan nel 10 for GS M, "Position" would be
selected. The cursor cont rol knob would t hen be used to go
to the r ight ha nd column in th e first row. This position
(for chan nel 10) would be selected, an d a "1" set t o activate
this ARFCN. When editing is complete, "Done" and then
"Activate d" are s elected. This t ells th e mobile to look for a
BCH on ARFCN 10.
5. Use th e selection knob to go into the "Aux BCCH " menu
Select "Adjacent "
This tur ns th e Modulat ion In /Out Da ta a nd Clock to OUT - the
HP 8922M will send data to the HP ESG-D signal genera tor.
POWER
Data
Clock
Power Divider (HP 11636A)RF IN/OUT RF OUTPUT
HP 8922 M HP ESG-D10 MHz Out 10 MHz In
Figure 16.
Diagram of se t-up
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Set up HP ESG-D signal generator
6. Press Frequency . Ent er "937MHz". This sets th e adjacent signal
to th e frequency chan nel ARFCN 10. Any ARFCN ma y be chosen,
provided it is different from th at set on HP 8922M
7. Press Ampl. Set t o the power level to a value different from tha ton the 8922M broadcast chan nel (i.e. 85dBm in t he default case).
The amplitude of the signal should be lar ger than the sensitivity
level of the mobile. For example, set t he a mplitude t o 100dBm.
In order t o ta ke into account th e insertion loss th rough th e power
divider, enter an am plitude offset in the Ampl menu. The typical
insert ion loss for a power divider is 6.2dB, therefore t he Amplitude
Offset should be set to 6.2dBm .
8. Press Mode.
Select GSM.
Select Data Format Pattern
Press the Data softkey
Select th e Ex t softkey. This means th at the dat a from the
8922M is the m odulation pr ovided.
Turn GSM On Offto GSM On .
9. Turn RF On Off to RF On .
Check that the mobi le can camp to both s ignals
10. Slowly decrea se the am plitude of th e signal of th e HP 8922M,
unt il it is much lower tha n th at of the HP ESG-D signal generat or.
The mobile should camp onto the signal from the s ignal generat or
becaus e its RxLev will be better. This can be verified by increasing
th e amplitude of signal from the HP ESG-D signal genera tor, and
checking tha t th e signa l stren gth on the m obile's display increases.
Lowering the am plitude of the signal genera tor should result in th e
displayed mobile signal level decreasing, until finally it will camp on
to the signal from the HP 8992M again.
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The receiver measu rements for r adios in th e GSM system m ake use Bit E rror
Rate (BER) techniques. A known pseudora ndom binar y sequence (PRBS) is
tr ans mitt ed to the m obile station which loops the received bits, after chann el
decoding, back to th e test equipmen t th rough its own tra nsm itter. The BER is
eva lua ted with in th e t est er (such as the HP 8922 GSM Mobile Station Test Set).In t he following sections, some key GSM mea sur ement s will be ma de using
th e HP 8922M GSM Mobile Sta tion Test Set a nd th e HP E SG-D series signal
generat or. Note th at t his is not a compr ehensive guide to the HP 8922M
Test Set, nor an in -depth stu dy of the GSM measur ement specifications.
For details of th ese area s, please refer to the HP 8922M documen ta tion and
th e relevant sections of the ETSI GSM specifications.
There a re formulae given in S ection 14 to convert ARFCNs into absolute
frequency values.
8.1 Receive r Co-Channe l Rejection
Co-cha nnel r ejection meas ur es a r eceiver's a bility to receive a wan ted m odu-
lated signal in th e presence of an unwan ted modulated signa l, both signals
being at th e same frequency. Bit error ra te is then measur ed to ensure the
receiver is r ejecting the un want ed signal. The test is described in detail in
the ETSI GSM Specifications 11.10 (Section 14.4)
The HP E SG-D series signal genera tor can be used as the un wanted source,
as it provides pr ecise 0.3GMSK modulation. The want ed signal can be gener -
ated using a test system such as the HP 8922M GSM MS Test Set.
Varia tions from t he GSM 11.10 Section 11.4.4 Test Recommen da tions
The HP 8922M does not us e the st anda rd t est signal "C1" for t he in-cha nnel
source. The sta nda rd test s ignal is a 1-0 pat tern with "dummy" bur sts for all
other t imeslots of the fra me. The HP 8922M uses a 1-0 data pa tt ern bu t does
not tra nsm it "dum my" burst s in all oth er timeslots. The HP 8922M can not
generat e a progress messa ge to the m obile station. This is a signaling
messa ge inst ead of speech. The HP 8922M does not simulat e fading.
An externa l fader, e.g. HP11759C, needs to be used with th e HP 8922M tomeet t he GSM recomm endat ion. The HP 8922M and HP ESG-D signa l gener-
at or can not test the m obile station in hopped mode, becaus e the E SG-D signal
generator cannot generate a hopping signal.
Co-Chann el Reject ion Measurem ent P rocedur e
POWER
Power Divider (HP 11636A)RF IN/OUT RF OUTPUT
HP 8922 M HP ESG-D10 MHz Out 10 MHz In
Figure 17.
Diagram of test se t-up
8. Using the ESG-D se ries
s ignal generator and
the HP 8922 GSM Tes t
Set to carry out GSMMS receive r tests
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Connect the HP 8922M MS Test S et, the HP ESG-D Signal
generator and the mobi le under test as sh own in Figur e 17.
1. Power on all equipment BUT ensur e the HP ESG-D signal genera
tor ha s RF On Offset to RF Off
Set u p the HP 8922M MS Test S et
2. Preset the HP 8922M. Press the Preset front panel ha rdkey.
3. Fr om the Cell Sta tus Screen, use th e cur sor control to scroll to
" To Screen, More".
4. Select "Cell Cont rol 2".
5. Fr om the Cell Cont rol 2 screen:
-Under "TCH Pa rm s" set th e following:
"TCH1"
Mode "Single"
ARFCN "60"
Check tha t "FS" is selected (this s hould be as it is
the default setting)
-Select "TCH Cont rol"
-Select "TCH1 Asgn"-Highlight "Execute
-Scroll to Audio Cnt l. Set "Loopback" to "FE"
(This turns Fr ame Era sure on)
-Set "Speech" to "PRBS "
-Set "PRBS Patt rn " to "10"
-Set "RF Gen" , "Amplitu de" to "85dBm" as d efined in t he
GSM specification. (Take into account the insertion loss
thr ough the power divider. For example, if the inser tion loss
for your power divider is 6.2dB, th e "Amplit ude" should be
set to 78.8 dBm to compensate for the loss. Alternatively,
the RF a mplitude offset field in t he HP 8922M I/O
configur ation could be set to account for th e loss thr ough
the divider.)
6. Check that the mobile is camped onto the signal from the HP 8922M.
7. Scroll to the lower right h and corn er men u, and select the
"BIT ERR 2" option. Under t he Bit E rr or Test screen "BIT ERR 2"
-Under "Meas Nu m 1","Type", select "ResTypeII ".
-Under "Bits t o Test", enter t he desired n umber of bits
accordin g to th e GSM specificat ions (see Table 14.14 on
Specifications 11.10). For exam ple, ent er "2,000,000".
-Under "Meas Nu m 2","Type", select "ResTypeIb".
-Under "Bits t o Test", enter t he desired n umber of bits
accordin g to th e GSM specificat ions (see Table 14.14 on
Specifications 11.10). For examp le, ent er "3,300,000".
-Un der "MS Loopba ck" ,"Loop Delay Speech Frms" set to "Auto".
Set up HP ESG-D signal generator
8. Press Frequency front pan el har dkey. Ent er "947MHz". This sets
th e inter fering signal to the sam e frequency channel as the in-cha nnel
signal (ARFCN 60)
9. P ress the Ampl front pan el ha rdkey. Set to "-94dBm" Compensa te
for t he inser tion loss th rough th e power divider by setting the
Amplitude Offset to 6.2dBm . This sets t he int erference signal t o 9dB
below the want ed signal, as specified in th e GSM recommendat ions.
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10. Press Mode .
Select GS M.
Se t Data Format Pattern Framed to Data Format Pattern
Select r andom da ta e.g. set Data to P N9
Turn GSM On Offto GSM On .
11. Turn RF On Offto RF On .
12. Set up a call from the mobile.
On the HP 8922M:
13.Under "MeasCntl" select "Single" and "Run". This will perform
the bit error test.
Compa re th e results t o those shown in the Test Limits Table in th e
GSM 11.10 Sp ecifications.
To change channel numbers for ad di t ional m easurements
14. Fr om the HP 8922M Cell Cont rol 2 screen:
-Under "TCH Par ms" set th e following:
"TCH1"
Mode "Single"
ARFCN - Enter the n ew chann el number you wantto test.
-Select "TCH Cont rol"
-Select "TCH1 Asgn"
-Highlight "Execute
15. Set the HP ESG-D signal genera tor Frequency to the frequency
of t he new chann el.
16. Repeat st eps 9 and 15 to measure bit-error rat e.
8.2 Adjacen t Chann el Rejection
Adjacent Ch ann el Rejection or Adjacent Cha nnel Selectivity mea sur es th e
GSM receiver's ability to reject a n un wanted signa l tha t is one or two cha nnelspacings from th e receiver's n ominal frequency. This is pr obably the most
importa nt out -of-chann el test per form ed on radios. It determ ines how well
th e radio will perform when other r adios are operated in t he adjacent RF
chann els. The t est is described in deta il in the E TSI GSM Specifications 11.10
(Test 14.5)
Testing adjacent channel selectivity requires a n in-cha nnel signal genera tor
set to the nominal center frequency of the r eceiver. This is a chieved by using
an H P 8922M Test Set t o esta blish a call with th e mobile on th e cha nnel
und er test . A second signal generat or is used to simulate a n un wanted or out-
of-chan nel signal. It s frequen cy is set to +/ one or two chann el spacings from
th e receiver's nominal cent er frequency, and is modulated with r andom da ta.
The outpu t level of the out-of-chan nel signal genera tor is set to a h igher level
(defined by the GSM sta ndar ds) than t he in-cha nnel signal generat or.
The HP ESG-D series signal genera tor can be used as t he out-of-channel
source, as it provides precise 0.3GMSK modulation. A featu re of the HP ESG
series signal genera tor is th at ther e ar e two choices available for optimizing
phase noise to suit your applicat ion.The ph ase-lock loop bandwidth may be
set to optimize ph ase noise for offsets below (Mode 1) or above (Mode 2)
10kHz offsets. For out-of-channel m easu remen ts (as in t his case), Mode 2
should be selected. This is the m ode selected a fter norm al preset , but t he
mode selection procedure will be described for futur e r eference purposes.
Varia tions from th e GSM 11.10 Section 11.4.5 Test Recomm enda tions
As sta ted in Section 4.1, th e HP 8922M does not generat e the sta ndar d test
signal "C1" or simu late fading.
Adjacent Cha nnel Reject ion Measurement Procedure
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Connect the HP 8922M MS Test S et, the HP ESG-D Signal
generator and the mobi le under test as show n in Figure 17
Power on all equipment BUT ensu re th e HP E SG-D signal generat or
has RF On Offset to RF Off
Set u p the HP 8922M MS Test S et
1. Preset the HP 8922M. Press the Pr eset front pan el har dkey.
2. From the Cell Statu s Screen, use the knob to scroll to Screen More
3. Select "Cell Cont rol 2".
4. Fr om the Cell Contr ol 2 screen:
-Under "TCH Par ms" set th e following:
"TCH1"
Mode "Single"ARFCN "60"
Check tha t "FS" is selected
(this should be as it is the default sett ing)
-Select "TCH Contr ol"
-Select "TCH1 Asgn"
-Highlight "Execute
-Scroll to Audio Cntl. Set "Loopback" to "FE"
(This turns Fr ame Era sure on)
-Set "Speech" to "PRBS "
-Set "PRBS Patt rn " to "10"
-Set "RF Gen" , "Amplitu de" to "85dBm" as d efined in t he
GSM specification. (Compensate for the insertion loss
th rough th e power divider).
5. Check that t he mobile is cam ped onto the HP 8922M.
6. Under t he Bit Err or Test screen "BIT ERR 2"
-Under "Meas Nu m 1","Type", select "ResTypeII".
-Under "Bits to Test", enter th e desired num ber of bits
accord ing to th e GSM specificat ions (see Table 14.21 on
Specificat ions 11.10). For exam ple, enter "600,000".
-Under "Meas Nu m 2","Type", select "ResTypeIb".
-Under "Bits to Test", enter th e desired num ber of bits
accord ing to th e GSM specificat ions (see Table 14.21 on
Specificat ions 11.10). For exam ple, enter "1,000,000".
-Under "MS Loopback","Loop Delay S peech Fr ms" se t
to "Auto".
Set up HP ESG-D signal gen erator
34
POWER
Power Divider (HP 11636A)RF IN/OUT RF OUTPUT
HP 8922 M HP ESG-D10 MHz Out 10 MHz In
Optional Diagram of set-up
(same as Co-Channe l Setup
Figure 17)
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35
7. Press Freq front pan el har dkey. Ent er "947.2 MHz". This sets t he
inter fering signal to the carrier frequency plus 200kHz (i.e. ARFCN 61).
The procedure to select phase noise Mode 2, will now be described.
Press the Optimize Noise softkey.
Press the Mode 2 Optimize > 10kHz Offset softkey.
8. Press Ampl front pa nel ha rdkey. Set t o "76dBm". Take into
account t he inser tion loss th rough th e power divider by setting
Amplitude Offset to, say, 6.2dBm. This sets th e am plitude of the
out-of-chann el signal to 9dB above tha t of the in-cha nnel signa l, as
specified in t he GSM r ecomm endat ions.
9. Press Mode .
Select GS M.
Se t Data Format Pattern Framed to Data Format
Pattern .
Select a random data pattern . Set Data , PN9 .
Turn GSM On Offto GSM On .
10. Turn RF On Offto RF On .
11. Set up a call from t he mobile.
On the HP 8922M:
12. Und er "MeasCn tl" select "Single" an d "Run ". This w