![Page 1: Measuring Your IBOC Spectrum David Maxson...3 First Thought IBOC is amazing Truly “Hybrid” of analog and digital Measurement issues will be addressed Signals measured differently](https://reader031.vdocuments.site/reader031/viewer/2022011818/5e90eaa8baa01c25b64f4954/html5/thumbnails/1.jpg)
1
Measuring Your IBOC Spectrum
David Maxson
![Page 2: Measuring Your IBOC Spectrum David Maxson...3 First Thought IBOC is amazing Truly “Hybrid” of analog and digital Measurement issues will be addressed Signals measured differently](https://reader031.vdocuments.site/reader031/viewer/2022011818/5e90eaa8baa01c25b64f4954/html5/thumbnails/2.jpg)
2
Topics
Measuring Power of Digital Waveforms
IBOC RF Mask
Digital Intermodulation and Interference
![Page 3: Measuring Your IBOC Spectrum David Maxson...3 First Thought IBOC is amazing Truly “Hybrid” of analog and digital Measurement issues will be addressed Signals measured differently](https://reader031.vdocuments.site/reader031/viewer/2022011818/5e90eaa8baa01c25b64f4954/html5/thumbnails/3.jpg)
3
First Thought
IBOC is amazing Truly “Hybrid” of analog and digital
Measurement issues will be addressed Signals measured differently Signals close in frequency
Interference issues are minor No FCC standards yet Working IBOC Mask
![Page 4: Measuring Your IBOC Spectrum David Maxson...3 First Thought IBOC is amazing Truly “Hybrid” of analog and digital Measurement issues will be addressed Signals measured differently](https://reader031.vdocuments.site/reader031/viewer/2022011818/5e90eaa8baa01c25b64f4954/html5/thumbnails/4.jpg)
4
FM analog carrier is the reference “dBc” is common term Helpful to differentiate dBc references for FM and for digital
Using “dBcFM” for analog FM reference Using “dBcPM” for IBOC Primary Main OFDM carrier power (stipulate bandwidth!)
Discussing Power
![Page 5: Measuring Your IBOC Spectrum David Maxson...3 First Thought IBOC is amazing Truly “Hybrid” of analog and digital Measurement issues will be addressed Signals measured differently](https://reader031.vdocuments.site/reader031/viewer/2022011818/5e90eaa8baa01c25b64f4954/html5/thumbnails/5.jpg)
5
Discussing Power
UNMODULATED
Underlying Graphic From NRSC
FM Reference0 dBcFM
1 kHz Slice
![Page 6: Measuring Your IBOC Spectrum David Maxson...3 First Thought IBOC is amazing Truly “Hybrid” of analog and digital Measurement issues will be addressed Signals measured differently](https://reader031.vdocuments.site/reader031/viewer/2022011818/5e90eaa8baa01c25b64f4954/html5/thumbnails/6.jpg)
6
Discussing Power
MODULATED
1 kHz Slice
![Page 7: Measuring Your IBOC Spectrum David Maxson...3 First Thought IBOC is amazing Truly “Hybrid” of analog and digital Measurement issues will be addressed Signals measured differently](https://reader031.vdocuments.site/reader031/viewer/2022011818/5e90eaa8baa01c25b64f4954/html5/thumbnails/7.jpg)
7
Discussing Power
MODULATED
300 kHz Slice
0 dBcFMFM Reference
![Page 8: Measuring Your IBOC Spectrum David Maxson...3 First Thought IBOC is amazing Truly “Hybrid” of analog and digital Measurement issues will be addressed Signals measured differently](https://reader031.vdocuments.site/reader031/viewer/2022011818/5e90eaa8baa01c25b64f4954/html5/thumbnails/8.jpg)
8
FM Power Reference Summary Use unmodulated carrier and narrow bandwidth
for most certain result Alternatively, measure full bandwidth
while modulated Be certain noise not a factor and no foreign energy in
bandwidth of analyzer
Watch your levels
Discussing Power
![Page 9: Measuring Your IBOC Spectrum David Maxson...3 First Thought IBOC is amazing Truly “Hybrid” of analog and digital Measurement issues will be addressed Signals measured differently](https://reader031.vdocuments.site/reader031/viewer/2022011818/5e90eaa8baa01c25b64f4954/html5/thumbnails/9.jpg)
9
Discussing Power
1 kHz Slice-41
dB/k
Hz
69 kHz Slice
-23
dB/6
9kH
z
![Page 10: Measuring Your IBOC Spectrum David Maxson...3 First Thought IBOC is amazing Truly “Hybrid” of analog and digital Measurement issues will be addressed Signals measured differently](https://reader031.vdocuments.site/reader031/viewer/2022011818/5e90eaa8baa01c25b64f4954/html5/thumbnails/10.jpg)
10
Discussing Power
IBOC Primary Main “subcarriers” Total digital power 20 dB down
(from FM analog)
One side 23 dB down Power in 1 kHz bandwidth 41 dB down System design specification
Balances analog compatibility with digital performance
![Page 11: Measuring Your IBOC Spectrum David Maxson...3 First Thought IBOC is amazing Truly “Hybrid” of analog and digital Measurement issues will be addressed Signals measured differently](https://reader031.vdocuments.site/reader031/viewer/2022011818/5e90eaa8baa01c25b64f4954/html5/thumbnails/11.jpg)
11
Discussing Power
IBOC Primary Main “subcarriers” Linear amplification Push transmitter into compression
For more efficiency Reduces hardware cost per watt
With compression comes intermodulation “Spectral regrowth”
![Page 12: Measuring Your IBOC Spectrum David Maxson...3 First Thought IBOC is amazing Truly “Hybrid” of analog and digital Measurement issues will be addressed Signals measured differently](https://reader031.vdocuments.site/reader031/viewer/2022011818/5e90eaa8baa01c25b64f4954/html5/thumbnails/12.jpg)
12
What’s the Opposite of “Compand”? Compress-Expand = Compand Expand-Compress = Express????
Precorrection is Expansion Anticipates the compression of the Power Amp
Precorrection
![Page 13: Measuring Your IBOC Spectrum David Maxson...3 First Thought IBOC is amazing Truly “Hybrid” of analog and digital Measurement issues will be addressed Signals measured differently](https://reader031.vdocuments.site/reader031/viewer/2022011818/5e90eaa8baa01c25b64f4954/html5/thumbnails/13.jpg)
13
Compression Example: A digital exciter without precorrection,
measured 6-7 dB peak to average power ratio After going through the PA,
peak to average 4-5 dB
Precorrection
![Page 14: Measuring Your IBOC Spectrum David Maxson...3 First Thought IBOC is amazing Truly “Hybrid” of analog and digital Measurement issues will be addressed Signals measured differently](https://reader031.vdocuments.site/reader031/viewer/2022011818/5e90eaa8baa01c25b64f4954/html5/thumbnails/14.jpg)
14
NO
Discussing PowerMidpoints +164 kHz
![Page 15: Measuring Your IBOC Spectrum David Maxson...3 First Thought IBOC is amazing Truly “Hybrid” of analog and digital Measurement issues will be addressed Signals measured differently](https://reader031.vdocuments.site/reader031/viewer/2022011818/5e90eaa8baa01c25b64f4954/html5/thumbnails/15.jpg)
15
Discussing PowerUpper and Lower PM Intermodulation at
+328 kHz Intervals
Center-492
(2A – B)
-164
(A)
+164
(B)
+492
(2B – A)
![Page 16: Measuring Your IBOC Spectrum David Maxson...3 First Thought IBOC is amazing Truly “Hybrid” of analog and digital Measurement issues will be addressed Signals measured differently](https://reader031.vdocuments.site/reader031/viewer/2022011818/5e90eaa8baa01c25b64f4954/html5/thumbnails/16.jpg)
16
Discussing PowerIntermodulation at +328 kHz Intervals
Center-164-820 +820+164-492 +492
4th
Adjacent
2 ½ th
Adjacent
![Page 17: Measuring Your IBOC Spectrum David Maxson...3 First Thought IBOC is amazing Truly “Hybrid” of analog and digital Measurement issues will be addressed Signals measured differently](https://reader031.vdocuments.site/reader031/viewer/2022011818/5e90eaa8baa01c25b64f4954/html5/thumbnails/17.jpg)
17
Primary Main IBOC at + 164 kHz
Regrowth at +492 kHz;
At +820 kHz
Discussing Power
Disclaimer:
Transmitter with
pre-correction disabled
OFDM Carriers in same group interact with each other
![Page 18: Measuring Your IBOC Spectrum David Maxson...3 First Thought IBOC is amazing Truly “Hybrid” of analog and digital Measurement issues will be addressed Signals measured differently](https://reader031.vdocuments.site/reader031/viewer/2022011818/5e90eaa8baa01c25b64f4954/html5/thumbnails/18.jpg)
18
Discussing Power
What Should
this Ratio Be?
![Page 19: Measuring Your IBOC Spectrum David Maxson...3 First Thought IBOC is amazing Truly “Hybrid” of analog and digital Measurement issues will be addressed Signals measured differently](https://reader031.vdocuments.site/reader031/viewer/2022011818/5e90eaa8baa01c25b64f4954/html5/thumbnails/19.jpg)
19
iBiquity RF Mask
Figure 3: iBiquity FM Hybrid Mode Noise and Spurious Emission Limits
Table 3: iBiquity FM Hybrid Mode Noise and Spurious Emission Limits
-40 dBcFM/kHz
-74.4 dBcFM/kHz
-80 dBcFM/kHz
![Page 20: Measuring Your IBOC Spectrum David Maxson...3 First Thought IBOC is amazing Truly “Hybrid” of analog and digital Measurement issues will be addressed Signals measured differently](https://reader031.vdocuments.site/reader031/viewer/2022011818/5e90eaa8baa01c25b64f4954/html5/thumbnails/20.jpg)
20
iBiquity RF Mask
Figure 3: iBiquity FM Hybrid Mode Noise and Spurious Emission Limits
Table 3: iBiquity FM Hybrid Mode Noise and Spurious Emission Limits
~ -34 dBPM/kHz
![Page 21: Measuring Your IBOC Spectrum David Maxson...3 First Thought IBOC is amazing Truly “Hybrid” of analog and digital Measurement issues will be addressed Signals measured differently](https://reader031.vdocuments.site/reader031/viewer/2022011818/5e90eaa8baa01c25b64f4954/html5/thumbnails/21.jpg)
21
iBiquity RF Mask
Figure 3: iBiquity FM Hybrid Mode Noise and Spurious Emission Limits
Table 3: iBiquity FM Hybrid Mode Noise and Spurious Emission Limits
~ -40 dBPM/kHz
600 kHz
Disclaimer:
This Proposed Mask is
based
on what is
practicable, not
necessarily on in
terference
protection analysis
![Page 22: Measuring Your IBOC Spectrum David Maxson...3 First Thought IBOC is amazing Truly “Hybrid” of analog and digital Measurement issues will be addressed Signals measured differently](https://reader031.vdocuments.site/reader031/viewer/2022011818/5e90eaa8baa01c25b64f4954/html5/thumbnails/22.jpg)
22
Why Regrowth Matters
Field Measurement with 4th Adjacent Signals
![Page 23: Measuring Your IBOC Spectrum David Maxson...3 First Thought IBOC is amazing Truly “Hybrid” of analog and digital Measurement issues will be addressed Signals measured differently](https://reader031.vdocuments.site/reader031/viewer/2022011818/5e90eaa8baa01c25b64f4954/html5/thumbnails/23.jpg)
23
What’s Wrong with this Picture?
Should Be< –80dBcFM
in 1kHz
Should Be< –74.4 dBcFM
in 1kHz
Issue: Mask at bottom of displayIssue: 3 kHz RBW overstates levels by 4.8 dB Issue: PM Energy not close to nominal levelIssue: 4th adjacent signal occludes regrowth
![Page 24: Measuring Your IBOC Spectrum David Maxson...3 First Thought IBOC is amazing Truly “Hybrid” of analog and digital Measurement issues will be addressed Signals measured differently](https://reader031.vdocuments.site/reader031/viewer/2022011818/5e90eaa8baa01c25b64f4954/html5/thumbnails/24.jpg)
24
Measurements
Vector Signal AnalyzerTheoretically idealComplexCost-prohibitive
![Page 25: Measuring Your IBOC Spectrum David Maxson...3 First Thought IBOC is amazing Truly “Hybrid” of analog and digital Measurement issues will be addressed Signals measured differently](https://reader031.vdocuments.site/reader031/viewer/2022011818/5e90eaa8baa01c25b64f4954/html5/thumbnails/25.jpg)
25
Measurements
Spectrum analyzerIsolates spectraSampling issuesDynamic range issues
![Page 26: Measuring Your IBOC Spectrum David Maxson...3 First Thought IBOC is amazing Truly “Hybrid” of analog and digital Measurement issues will be addressed Signals measured differently](https://reader031.vdocuments.site/reader031/viewer/2022011818/5e90eaa8baa01c25b64f4954/html5/thumbnails/26.jpg)
26
Measurements
Power MeterPreciseDoesn’t differentiate signal components
![Page 27: Measuring Your IBOC Spectrum David Maxson...3 First Thought IBOC is amazing Truly “Hybrid” of analog and digital Measurement issues will be addressed Signals measured differently](https://reader031.vdocuments.site/reader031/viewer/2022011818/5e90eaa8baa01c25b64f4954/html5/thumbnails/27.jpg)
27
Measurements
Spectrum AnalyzerVariations among detectors
The noise-like waveform problem Level understated by ~2dB
![Page 28: Measuring Your IBOC Spectrum David Maxson...3 First Thought IBOC is amazing Truly “Hybrid” of analog and digital Measurement issues will be addressed Signals measured differently](https://reader031.vdocuments.site/reader031/viewer/2022011818/5e90eaa8baa01c25b64f4954/html5/thumbnails/28.jpg)
28
Measurements
Spectrum AnalyzerVariations among detection modes
“Sample”Random sample in each “bin”Average of series of random samples (by averaging n sweeps)
“Max-Min”Average Max and Min values in successive sweeps
Video filteringPeak
![Page 29: Measuring Your IBOC Spectrum David Maxson...3 First Thought IBOC is amazing Truly “Hybrid” of analog and digital Measurement issues will be addressed Signals measured differently](https://reader031.vdocuments.site/reader031/viewer/2022011818/5e90eaa8baa01c25b64f4954/html5/thumbnails/29.jpg)
29
Measurements
Spectrum analyzers
Peak Hold
Peak Average
Max-Min Average
![Page 30: Measuring Your IBOC Spectrum David Maxson...3 First Thought IBOC is amazing Truly “Hybrid” of analog and digital Measurement issues will be addressed Signals measured differently](https://reader031.vdocuments.site/reader031/viewer/2022011818/5e90eaa8baa01c25b64f4954/html5/thumbnails/30.jpg)
30
Measurements
Spectrum analyzers Any
sampling mode shows
relation between PM and regrowth
![Page 31: Measuring Your IBOC Spectrum David Maxson...3 First Thought IBOC is amazing Truly “Hybrid” of analog and digital Measurement issues will be addressed Signals measured differently](https://reader031.vdocuments.site/reader031/viewer/2022011818/5e90eaa8baa01c25b64f4954/html5/thumbnails/31.jpg)
31
Measurements
Case StudyKUVO, DenverNautel V-10 Transmitter
Adaptive Precorrection
![Page 32: Measuring Your IBOC Spectrum David Maxson...3 First Thought IBOC is amazing Truly “Hybrid” of analog and digital Measurement issues will be addressed Signals measured differently](https://reader031.vdocuments.site/reader031/viewer/2022011818/5e90eaa8baa01c25b64f4954/html5/thumbnails/32.jpg)
32
KUVO Nautel Flow
Pre-correction Digital to RF
Conversion Digital Summing
Digitized Primary Main
Carriers
Digitized Analog FM
Carrier
Power Amplification
RF to Digital Conversion
Comparator
Adaptation
Adaptive Pre-correction LoopMeasurement
Point
![Page 33: Measuring Your IBOC Spectrum David Maxson...3 First Thought IBOC is amazing Truly “Hybrid” of analog and digital Measurement issues will be addressed Signals measured differently](https://reader031.vdocuments.site/reader031/viewer/2022011818/5e90eaa8baa01c25b64f4954/html5/thumbnails/33.jpg)
33
Measurements
KUVOFM only
![Page 34: Measuring Your IBOC Spectrum David Maxson...3 First Thought IBOC is amazing Truly “Hybrid” of analog and digital Measurement issues will be addressed Signals measured differently](https://reader031.vdocuments.site/reader031/viewer/2022011818/5e90eaa8baa01c25b64f4954/html5/thumbnails/34.jpg)
34
Channel Power Analyzer
utility Computes
power ina bandwidth
Measurements
![Page 35: Measuring Your IBOC Spectrum David Maxson...3 First Thought IBOC is amazing Truly “Hybrid” of analog and digital Measurement issues will be addressed Signals measured differently](https://reader031.vdocuments.site/reader031/viewer/2022011818/5e90eaa8baa01c25b64f4954/html5/thumbnails/35.jpg)
35
Positive Peaks Averaged
Sample Averaged
Measurements
![Page 36: Measuring Your IBOC Spectrum David Maxson...3 First Thought IBOC is amazing Truly “Hybrid” of analog and digital Measurement issues will be addressed Signals measured differently](https://reader031.vdocuments.site/reader031/viewer/2022011818/5e90eaa8baa01c25b64f4954/html5/thumbnails/36.jpg)
36
Measurements
10 Hz Video Band Width (yellow)40x sample average (green)
![Page 37: Measuring Your IBOC Spectrum David Maxson...3 First Thought IBOC is amazing Truly “Hybrid” of analog and digital Measurement issues will be addressed Signals measured differently](https://reader031.vdocuments.site/reader031/viewer/2022011818/5e90eaa8baa01c25b64f4954/html5/thumbnails/37.jpg)
37
Adaptive Precorrection
![Page 38: Measuring Your IBOC Spectrum David Maxson...3 First Thought IBOC is amazing Truly “Hybrid” of analog and digital Measurement issues will be addressed Signals measured differently](https://reader031.vdocuments.site/reader031/viewer/2022011818/5e90eaa8baa01c25b64f4954/html5/thumbnails/38.jpg)
38
Common Amplification Analog Signal Amplified with Digital More Points of Regrowth
Common Amplification
![Page 39: Measuring Your IBOC Spectrum David Maxson...3 First Thought IBOC is amazing Truly “Hybrid” of analog and digital Measurement issues will be addressed Signals measured differently](https://reader031.vdocuments.site/reader031/viewer/2022011818/5e90eaa8baa01c25b64f4954/html5/thumbnails/39.jpg)
39
Common AmplificationIntermodulation at +328 kHz Intervals
Center-164-820 +820+164-492
Intermodulation at +164 kHz Intervals
+492
![Page 40: Measuring Your IBOC Spectrum David Maxson...3 First Thought IBOC is amazing Truly “Hybrid” of analog and digital Measurement issues will be addressed Signals measured differently](https://reader031.vdocuments.site/reader031/viewer/2022011818/5e90eaa8baa01c25b64f4954/html5/thumbnails/40.jpg)
40
How to Do It
Where to sample?If digital-only is accessible, check it out
Helps verify analyzer settings before dealing with extra analog powerMay be only way with separate antennas
![Page 41: Measuring Your IBOC Spectrum David Maxson...3 First Thought IBOC is amazing Truly “Hybrid” of analog and digital Measurement issues will be addressed Signals measured differently](https://reader031.vdocuments.site/reader031/viewer/2022011818/5e90eaa8baa01c25b64f4954/html5/thumbnails/41.jpg)
41
How to Do It
Where to sample?If signals are combined before antenna, sample thereWatch out for other signal ingress
Combiner systems, local signalsCould overload analyzer
![Page 42: Measuring Your IBOC Spectrum David Maxson...3 First Thought IBOC is amazing Truly “Hybrid” of analog and digital Measurement issues will be addressed Signals measured differently](https://reader031.vdocuments.site/reader031/viewer/2022011818/5e90eaa8baa01c25b64f4954/html5/thumbnails/42.jpg)
42
How to Do It
Where to sample?Off-air sampling is most challengingMay be only way to see full hybrid signal
![Page 43: Measuring Your IBOC Spectrum David Maxson...3 First Thought IBOC is amazing Truly “Hybrid” of analog and digital Measurement issues will be addressed Signals measured differently](https://reader031.vdocuments.site/reader031/viewer/2022011818/5e90eaa8baa01c25b64f4954/html5/thumbnails/43.jpg)
43
How to Do It
Analyzer settingMust have good intermodulation specs100-dB on-screen range helpfulRead The Manual!
Total power into analyzer must be safely below analyzer compressionMinimum measured signal must be above instrument noise floor
![Page 44: Measuring Your IBOC Spectrum David Maxson...3 First Thought IBOC is amazing Truly “Hybrid” of analog and digital Measurement issues will be addressed Signals measured differently](https://reader031.vdocuments.site/reader031/viewer/2022011818/5e90eaa8baa01c25b64f4954/html5/thumbnails/44.jpg)
44
How to Do It
Analyzer settingChannel Power computation feature
Most desirable
Sample detection mode and multi-sweep averaging
Good (15 sweeps OK, 50 pretty)
Max-Min (a.k.a. Pos-Neg) trace averagingLess precise
Very narrow Video Bandwidth In the ballpark, but slow and less precise.
![Page 45: Measuring Your IBOC Spectrum David Maxson...3 First Thought IBOC is amazing Truly “Hybrid” of analog and digital Measurement issues will be addressed Signals measured differently](https://reader031.vdocuments.site/reader031/viewer/2022011818/5e90eaa8baa01c25b64f4954/html5/thumbnails/45.jpg)
45
Acknowledgements
Mike Pappas and
The KVOD Crew
Mike Woods,
Chris Mahaney
![Page 46: Measuring Your IBOC Spectrum David Maxson...3 First Thought IBOC is amazing Truly “Hybrid” of analog and digital Measurement issues will be addressed Signals measured differently](https://reader031.vdocuments.site/reader031/viewer/2022011818/5e90eaa8baa01c25b64f4954/html5/thumbnails/46.jpg)
46
Thank You
www.broadcastsignallab.com