BCARESAdvanced TV Training

Jim Andrews, KH6HTV

Topics to be Covered• Operation of new generation, synthesized, VUSB-TV

Transmitters.• Operation of 23cm FM-TV transmitters and receivers.• Operation of Sheriff’s SWAT QUAD TV receiver• Operation of EOC QUAD TV receiver & Situation

Room large screen monitors• Theory of TV Repeaters• Operation of Chautauqua Park TV Repeater• Operation of Portable TV Repeater• Field Exercise to setup & operate all of the above

2 meter TV Voice Communications

• BCARES uses 144.37 MHz FM• Why ?• Avoid TVI due to 2 meter 3ed harmonic• 146.52 x 3 = 439.56 Channel 60 !• 144.37 x 3 = 433.11

QST – Feb 2013

Hi Definition – Digital TV• BCARES is not now using DTV, only

standard definition, analog, NTSC with either VUSB-TV or FM-TV

• Why ?• Field studies have shown issues with

multi-path propagation• May be added as an extra feature in the

future to Chautauqua Park TV Repeater

70cm VUSB-TV Transmitter• Uses NTSC standard

VUSB modulation• Frequency

Synthesized – channels 57 thru 61

• 10 Watts PEP• Rugged design for

field operations• Simple Controls

Vestigal Upper Sidebandis basically AM modulation with the video carrier, upper

sideband and a small portion of the lower sidebandPer FCC channel width = 6 MHz

Spectrum Plots at 10dB/div vert & 10 MHz/div horizTypical Ham AM-TV Spectrum VUSB-TV Spectrum

23cm FM-TV

• Why FM ? --- The same reason we use FM for voice on 2 meters. Improved performance over AM. AM-TV or VUSB-TV requires 40dB s/n for P5 picture. Due to FM quieting effect, FM-TV only requires about 13dB s/n for P5 picture.

• We can thus get a P5 picture through using lower power.

Why not FM-TV on 70cm ?• The FM spectrum is

too broad. 20+MHz vs. 6 MHz

• FM-TV spectrum plots 10dB/div & 10MHz/div Bottom is 4 MHz deviation “live” video modulation. Top is with stereo sound subcarriers (SSC) added

• 60 MHz wide, 23cm band is capable of supporting 2 or at most 3 FM-TV transmitters.

• Turn Off the Sound Sub-Carriers (SSC) when not needed.

• BCARES mainly uses FM-TV for “point-to-point” microwave links

HF Technology – 23cm FM-TV Transmitter

• 1 Watt, 3 channel synthesized

• Very simple controls• Power On/Off• SSC On/Off• RF Power 1W,

100mW or 10mW• Channel A, B or C

HF Technology 23cm FM-TV Receiver

• 2 modules – top is VCO tunable down-converter – bottom is 70MHz IF & demodulator

• Chan/Tune switch selects either tunable VCO (1240-1300MHz) or pre-set channels A, B or C

• IF Module – set Video Polarity to “Normal”, set Audio Tune to 5.8MHz SSC, set Audio Level to max. CW

KH6HTV VIDEO model 23-123cm FM-TV Transmitter

• 3 Watts RF Power• Frequency Synthesized,

3 channels, diode programmed

• Standard Definition Video 480i, plus stereo audio on 2 Sound Sub-Carriers

• 12 Vdc, 1 Amp• Simple Controls• Companion Receiver

currently under development.

23cm Antennas

QUAD TV Receiver• Basic concept – Four

separate TV receivers (demodulators) feed a Quad Processor which creates a single video picture with four separate images in the four quadrants

SWAT Quad Box Control Panel

EOC Large Screen Monitors

Chautauqua Park TV Repeater• Covers eastern ½ of

county and beyond• P3 at DIA, 35 miles• DX to Parker, 50

miles• More details on

www.qrz.com• Call sign – W0BCR

Chautauqua Park TV Repeater Control

• Trustee is Jim Andrews, KH6HTV• Control is via DTMF tones on a separate

radio link• Control Frequency, access code & control

codes are “confidential”. They are only given to BCARES members that also have their own home ATV equipment.

• Frequency coordination issues

Chautauqua Park TV Repeater Control Codes

• Beacon Mode with Color Bar ID – On/Off• Receiver Select -- 23cm FM or 70cm

VUSB• 70cm Transmitter – Enabled / Disabled• System Master Reset

Cross Band TV Repeater• A simple cross-band TV repeater can be

configured using a 70cm VUSB-TV receiver feeding directly into a 23cm FM-TV transmitter

• Example: use the video output from the quad box and patch directly to the HF Tech transmitter

• More isolation problems if doing 23cm input and 70cm (ch 57) output due to transmitter’s 3ed harmonic, i.e. do not use 1277 (Ch B) as input

• A single tri-band (2m/70cm/23cm) omni antenna can by used along with a triplexer 55dB isolation

More ATV Information

• KH6HTV VIDEO web site• www.kh6htv.com • Lots of ATV & DTV Application Notes• Reprints of articles from QST and ATV

Quarterly

BCARES Advanced TV Trainingpresented by

Jim Andrews, KH6HTVJuly, 2013