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The TWIST-AUTO system including TWIST-R-AUTO and TWIST-TA.
1. Active automatic TWIST-R-AUTO receiver which converts a differential video signal into a standard one and is installed on the receiving end of the video line.
2. Active TWIST-TA transmitter which converts a signal from the source (video camera) into a differential video signal and is installed on the transmitting end of the video line.
When the TWIST-TA transmitter on the transmitting end of the video line and TWIST-R-AUTO receiver on the receiving end of the video line are connected in series, a high-quality colour video signal is transmitted through the unshielded twisted pair (UTP) cable at a distance of up to 900 metres.
The automatic TWIST-R-AUTO receiver has a differential input for the UTP cable in the form of a three-contact connector. Two contacts are for connecting to the UTPcable, while the third is for the earth. The coaxial 75 ohm BNC output connector is intended for the output of a standard video signal.
The automatic receiver converts differential video signals into standard single-ended ones. There is also a system of automatic frequency corrections of differential video signals for compensating high-frequency loses in a long video-transmission line, an automatic adjustment of video signal level for PAL or NTSC colour video signal. The receiver has indicators for video signal presence and automatic operating.
The receiver has input protection from impulse current surges with an amplitude of up to 5 kA and a pulse width of up to 8/20µs, and also protection from constant differential voltage of up to 15 V or common voltage between the earth wire and cable wires of up to ±12 V.
The TWIST- TA transmitter has a coaxial 75-ohm BNC input connector and differential outputs made in the form of a three-contact connector. Two contacts are for connecting the twisted pair cable while the third is for the earth.
The transmitter converts a standard video signal into a differential video signal . Also it makes preliminary frequency corrections of differential video signals for compensating high-frequency losses in a long video transmission line.
The transmitter has output protection from impulse current surges with amplitudes of up to 5 kA and pulse width of up to 8/20µs, as well as protection from constant differential voltage of up to 15 V or common voltage between the earth wire and cable wires of up to ±12 V.
Both devices have a built-in power unit for AC power supply 230 V with electronic protection.
These devices are for outdoor use (category IP54) and are exclusively made using integral circuits manufactured by MAXIM (USA) and RD ALFA MD. They are reliable, user-friendly and have low power consumption.
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Technical Characteristics : TWIST-TA
| Parameter |
Value |
| Total amplitude of input video signal |
0.7-1.5 V |
| Resistance for coaxial input |
75 Ohm |
| Wave resistance of twisted pair of wires |
100 Ohm |
| Pass–band |
7 MHz |
| Input–output transfer rate number |
1 |
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Discrete control of amplitude – frequency
characteristic (at frequency 7 MHz)
|
0-12-18-22 dB |
| Ratio signal/noise |
50 dB |
| Max. useful current of transmitter |
30 mA |
| Supply voltage (AC 50 Hz) |
230 V |
| Dimensions |
110 x 80 x 40 mm |
| Weight |
100 g |
| Max. distance of transmission |
900 m. |
Technical Characteristics : TWIST-R-AUTO
| Parameter |
Value |
| Total amplitude of input video signal |
0.5-2.5 V |
| Resistance for coaxial input |
75 Ohm |
| Wave resistance of twisted pair of wires |
100 Ohm |
| Pass-band |
7 MHz |
| Input–output transfer rate (automatically controlled) |
1.5 |
Range of control of amplitude–frequency characteristic
at frequency 4.43 mHz (automatically controlled) |
18 dB |
| Gain adjustment range (automatically controlled) |
9 dB |
| Common-mode signal suppression |
50 dB |
| Max. useful current of receiver |
70 mA |
| Supply voltage (AC 50 Hz) |
230 V |
| Dimensions |
110 x 80 x 40 mm |
| Weight |
120 g |
| Max. distance of transmission |
900 m |
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Maximum allowed voltages in video line
Differential voltage on signal wires, not more than
Common voltage between the earth wire and cable wires up to
Amplitude of impulse current surges up to
Pulse width up to |
Value
15 V
± 12 V
5kA
8/20 µs |
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Electronic equipment for transmission of video signals through unshielded twisted pair (UTP) cable of up to 900 metres
High-quality transmission
of video signals through
UTP cable at distance
of up to 900 meters
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Automatic frequency
corrections and
automatic adjustment
of video signal
level
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Fast black
level clamping of
the video signal ___________________
The receiver has
indicators for video
signal presence and
automatic operation
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Built-in power unit
with electronic protection
___________________
Devices are dust,
water and shockproof (IP54)
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