Toshiba RF Receiver for HDTV

Final Presentation: 12/9/2004

Team:Josue Caballero, Brett DiCio, Daniel Hooper, Efosa Ojomo, George Sewell

Background Information

● Our sponsor is Aaron Foster– Engineering Manager– Production Engineering– TOSHIBA America Consumer Products, Inc.

Manufacturing Division● TOSHIBA plant is in Lebanon, TN

– Produces projection screen, and DLP (digital light projection) TVs

Problem Statement

● Coaxial cable to be attached to the television’s tuner/RF switch

● Cable can fall off, damaging assembly line or TV, incurring repair costs

● Cable becomes damaged with use, needing replacement● Damaged cable can cause TV rejection, affecting

productivity● Cost for the simple task of connecting and disconnecting

coax is high (labor)

Project Requirements● Design a cost efficient wireless system● Transmits factory generated signals to be received

at specified signal strength (ex. 40/65/>85 μ dB)– UHF: Ultra High Frequency– VHF: Very High Frequency– ATSC: Advanced Telecommunications Standards

Committee – CATV: Cable Television– QAM: Quadrature Amplitude Modulation

● The operational frequency range should be between 55.25 and 805.75 MHz.

Operational Concept

● Assembly Line– From clean room

● Hood with the mirror are attached● Inspected for contaminants

– Antenna is attached to the Cable TV input● We are unconcerned with any other input

– Every other TV is being tested at any time● Each station has own computer and camera

Operational Concept (Continued)

Operational Concept (Continued)

● Test Stations– Camera has IR transmitter to change channel to test

pattern required– Each camera is connected to computer and screen is

measured for picture accuracy– Antenna in back of TV, lines up with transmitter

antenna

Operational Concept (Continued)

Operational Concept (Continued)

● Test Signal– Test patterns are generated in house– Signal strength can be adjusted at each station

● dB specification is very specific, and derived from FCC regulations– Low-power signals must be interpreted correctly– V-Chip (Violence - Chip)– Closed Captioning (CC)

Test Frequency Plan

• 60-80% of the receiver RF testing occurs in the Very High Frequency (VHF) band– VHF (30 MHz to 300 MHz)

– Channels 3, 6, 7, 9, 12• 61.25, 83.25, 175.25, 187.25, 205.25 MHz

– UHF (300 MHz to 3.0 GHz)– Channels 14, 36, 69• 471.25 , 603.25, 801.25 MHz

– Cable – Channels 15, 16, 23, 24, 25, 48, 49• 127.25, 133.25, 217.25, 223.25, 229.25, 367.25, 373.25 MHz

Frequency Allocations

• The frequencies to be tested can be divided into two “bands” for the purpose of test set design

• VHF Band: 61.25 MHz to 373.25 MHz• 61.25, 83.25, 127.12, 133.25, 175.25, 187.25, 205.25,

205.25, 217.25, 223.25, 229.25, 367.25 MHz• UHF Band: 300 MHz to 1.0 GHz• 373.25, 471.25, 603.25, 801.25 MHz

Frequency Band Designations

Operational Environment

● Assembly line design means short distance between test stations (interference)

● Assembly line machinery creates EM background noise

● Rough handling of components– Easily damaged

● TVs manually placed on line causes inconsistencies when lining up with antenna

Current Solution Problems

● Stripped coax cable twisted into a bent oval for transmission antenna

● Stripped coax cable coiled around a rod for receiving antenna

● Inefficient design– Allows significant interference with adjacent systems– Designs are barely compatible, but work

Left Side

Top View

Antenna Design

● RF (radio frequency) Transmission– Wavelength– Antenna length

● EM Fields (electromagnetic)– Shape of antenna determines direction of flow– High directionality is has a negative impact on

bandwidth

Antenna Testing

● Equipment from Toshiba– Signal generator

– Spectrum analyzer

● Setup– Signal generator connected to test transmit antenna

– Spectrum analyzer connected to test receive antenna

– Measurements taken based on received power at a range of frequencies

– Antenna is evaluated based on bandwidth and reliability

Antenna Testing (Continued)

● Microwave signal generator– Thermal damage– Excessive cell heating, burns at high energy

● Protection– Stand away, monitor output, shielding

● Communications Interference– Aluminum foil provides adequate shielding

● Skin depth at 50MHz is 12 μm

Desired Design Specifications

● Highly directional antennas– Less errant signals / strong gain

● Support tested bandwidth– Bandwidth (55.25 – 805.75 MHz, individual/multiple)

● Antenna Gain– “Antenna gain is defined as the power output, in a

particular direction, compared to ...any direction by a perfect omni-directional antenna.” (Stallings, 109)

Design Considerations

• Current design in use– Bent toroid transmitter– Coiled receiver

• Possible designs– Waveguide horn design– Multiple antenna design

Advantages

• Horn waveguide– Single design– Wide bandwidth– Good directionality

• Multiple Antennas– Easier design– More reliable in factory

environment– Each station customized

to specific needs

Disadvantages

● Horn waveguide– Very susceptible to design variations– Very susceptible to physical damage– Exotic design

● Multiple Antennas– More labor – SWR concerns (standing wave ratio)– Multiple designs means more custom maintenance

References

● www.microsoft.com visio free trial

● Cheng, David K.; Field and Wave Electromagnetics; Prentice Hall, 2nd ed. 1989.

● http://www-pw.physics.uiowa.edu/plasma-wave/istp/polar/fig3.gif

● http://www.bsjm.com.cn/04/images/mdsbxz.jpg

● http://www.ntia.doc.gov/osmhome/allochrt.pdf

● http://www.gpsw.co.uk/ProdImg/prod1875s.jpg

● http://www.ramayes.com/horn_antennas.htm● “Data and Computer Communications”, William Stallings,

2004 (C)Prentice Hall New Jersey pg. 109