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QAM: 32/64 /128/256 Scrambling Converter
A multifunctional device that converts 8 ASI digital streams in DVB-C signal on the intermediate frequency of the cable television.
This device is a component part of the hardware-software system which includes operator's control computer with a control program and up to 32 devices.
Each 8 ASI/DVB-C device allows forming a required packet of digital programs out of ASI digital streams on its 8 inputs and forms this packet on one subcarrier according to the DVB-C standard.
The signal at the output of the device is fed to the input of the intermediate frequency channel modulator of the head-end. The device realizes all the necessary ASI input signal transformations for digital television broadcasting on existing cable television networks including protection from an unauthorized access (CAS).
8ASI/DVB-C Scrambling device can be also used with an analog cable network equipment broadcasting simultaneously in the same network both analog and digital signals.
PC connection interface Ethernet 100T in comparison with USB/RS-485 interface allows speeding up data exchange between a computer and the device as well as improving the efficiency in device servicing. A parallel operation in two interfaces is possible.
The device provides both SD (Standard Definition) and HD (High Definition with high resolution 1920Ч1080i in H.264 standard) video encoding. The ability to work with HD signals gives an opportunity to meet the needs of big screen HD-ready TV owners.
Standard digital cable TV broadcasting receivers DVB-C ( SD or HD ) are used as a subscriber receiver.
The device is produced in several modifications which differ in functional capabilities.
Features.
Re-multiplexing of digital input streams is a formation of optional program packages. The programs are selected by the operator out of 8 ASI input digital streams using a specialized Program which is a part of the supply.
Choice of output signal modulation type QAM 32/64/128/256.
Digital stream analyzer The number of transmitted programs in the device’s output signal within the skipped data stream is determined by the cable network operator and directly depends on the programs’ speed in the received transport stream from the satellite. The stream speed of MPEG-2 compressed programs of standard resolution with a good quality is generally 4-5 Mbit/s. The theoretical bandwidth limit of the device (the stream that can be skipped in an idle case) is determined by the selected QAM modulation. The higher is QAM modulation the bigger is the bandwidth limit, noise immunity although decreases and consists, for example, 36,34 Mbit/s for QAM 64. Correspondingly, for this case it can be theoretically transmitted approximately 36/5=7 programs. Hereof 7-8 TV programs of standard resolution and 10-15 radio programs, which are transmitted on one carrier according to DVB-C standard in spectrum width up to 8 MHz.
In the future when moving to MPEG4-AVC broadcasting the number of programs in standard resolution can be increased in 1,5 -2 times.
An analyzer of digital streams, which is a part of the Program, allows creating a program package with a total stream that can provide a sustainable work for the system. In practice, streams from the satellite have variable speed and in separate limits of time the speed of some programs, being summed up can significantly exceed the bandwidth limit of the channel. The operator must always remember about that and take it into consideration when forming the package.
The ability to set the output signal frequency in the band range from 26 to 40 MHz.
The frequency is set by the operator using DVCrypt utility.
Conditional access system support.
A built-in block of channel closing from unauthorized access provides an opportunity to use the device in the DVCryp conditional access system.
The set options are carried out from the personal computer through a supply of the specialized Utilities.
Ability to work with HD signals.
An optional supply with built-in up-device that transfers the intermediate frequency to the channel frequency is possible.
EPG and network search functions support.
Technical Specifications
- Output signal modulation type QАМ 32/64 /128/256
- Maximum input bitrate up to 100Мbit/s
- Symbol rate for QAM64 6750ksimbol/s
- Output bitrate for QAM64 36,34 Mbit/s
- DVB-C signal frequency band output no more than 8 MHz
- Output level (IF) -18 dBmV/75W /-6dB
- Returning range output 26 – 40.0 MHz
- ASI signal input level (EN 50083-9:1998) 800 mV+/-10%
- Computer connection interface Ethernet 100T
- ASI input connector BNC-type
- Output connector F
- Power supply 220V+\_20%
- Power consumption <30W
- Dimensions 19``, 1U 480*45*180 mm,
- Weight 3,5 kg
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