The following video signal equipment shall conform to EIA 170.
Electrically powered equipment shall operate on 120 Volts 60 Hz AC power.
All video signal inputs and outputs shall be by BNC connectors.
2.13.1
Ground Loop Corrector
The ground loop corrector shall eliminate the measured ground loop
interference (common mode voltage) in wireline or coaxial video
transmission lines. The ground loop corrector shall pass the full
transmitted video bandwidth with no signal attenuation or loss. Clamping
ground loop correctors shall be capable of rejecting at least an 8 volt
peak-to-peak 60 Hz common mode signal. Ground isolation transformers shall
be capable of rejecting at least a 10 volt peak-to-peak 60 Hz common mode
signal. Ground isolation amplifiers shall be capable of rejecting at least
a 30 volt peak-to-peak 60 Hz common mode signal. Differential ground loop
correctors shall be capable of rejecting at least a 100 volt peak-to-peak
60 Hz common mode signal.
2.13.2
Video Loss/Presence Detector
The video loss/presence detector shall monitor video transmission lines for
presence of the video signal. The detector shall annunciate an alarm when
the video signal drops below a pre-set threshold level. A threshold level
adjustment shall be provided for each video channel, and the threshold
level shall be continuously adjustable through a lockable front panel
control. A front panel reset control shall be provided for each video
channel, which shall reset the detector after an alarm. The video loss
alarm shall be annunciated through a front panel LED and a contact closure
as a minimum. Video input shall be loop-through, and the video shall be
unaffected when the detector is turned off. The detector shall not
attenuate or reduce the level of the video signal passing through it.
2.13.3
Video Equalizing Amplifier
The video equalizing amplifier shall be designed to correct loss in video
signal level and high frequency attenuation caused by long distance video
signal transmission over wireline DTM. The amplifier shall have
independent signal gain and equalization controls. The amplifier shall be
capable of equalizing at least 900 m (3000 feet) 3000 feet of RG-11/U
coaxial cable conforming to paragraph CCTV Equipment Video Signal Wiring.
The amplifier shall provide a minimum of plus or minus 6 dB of video gain
and 12 dB of high frequency compensation. At least one video output shall
be provided for each video input. Bandwidth shall be 10 MHz or greater,
and frequency response to 8 MHz shall be plus or minus 1 dB or less. Hum
and noise shall be 50 dB below 1 volt peak-to-peak or better. Video inputs
shall be 75 ohm unbalanced, terminating, differential grounded. Video
outputs shall be 75 ohm, differential, source terminated, 1 volt
peak-to-peak. Output isolation shall be 40 dB or greater at 5 MHz.
2.13.4
Video Distribution Amplifier
The video distribution amplifier shall be designed to distribute a single,
75 ohm, unbalanced video input signal to a minimum of 4, 75 ohm, source
terminated video outputs. The distribution amplifier shall have not less
than plus or minus 3 dB of gain adjustment for the video output. Output
isolation shall be 40 dB or greater at 5 MHz. Bandwidth shall be 10 MHz or
greater, and frequency response to 8 MHz shall be plus or minus 0.5 dB or
less. Hum and noise shall be 55 dB below 1 volt peak-to-peak or better.
SECTION 16751A
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