Digital modem Contact 11M.2M16.QAM


      A "Contact 11M.2M16.QAM" digital modem (modem) operates in the frequency range of 4,0...15,0 MHz and is intended for transmission of sixteen independent 2,048 Mbit/s digital bitstreams (E1) for telephone communication, Internet and other applications by means of analog communication line (including analog radio relay stations for TV transmission and telephony).
     It is possible to use a QAM-64 modulation in the modem, with a band width (at a -30dB level) of 7,6 MHz, modulator output level (the maximum level): 0 dBm.
     The modem can be used in the radio relay stations of preceding generations, where one frequency band of 30 MHz is emitted while transmitting of one TV channel; modulation kind is a frequency modulation kind. It is possible to locate one TV channel and sixteen E1 bitstreams in a 30 MHz band using a narrow-band FM by adding sixteen E1 bitstreams to a TV channel band with the help of the "Contact 11M.2M16.QAM" (it results in extending of a modulating function from 7 MHz to 15 MHz).

Product specifications
IF frequency tuning 4.0...15.0 MHz
Tuning step 250 kHz
Output level (the maximum level) 0dBm
Attenuator analog 0...20 dB
digital 0...20 dB
Modulation kind QAM64
Frequency band at the level of -30dB QAM64 7.6 MHz
QAM128 6.1 MHz
Sensitivity (BER<10-6), not worse than -55 dBm
Maximum input level not less than -10 dBm
Signal-to-noise ratio (BER<10-9), not worse than 28 dB
Antinoise coding Reed-Solomon 204/188, interleaving
Carrier capacity 34368 Kbit/s
Interface E1 G.703, HDB3/AMI, 120 Ω
Maximum length of a communication line of an interface E1 (STP cable, category 5) 1.2 km
Multiplexing ITU-T G.742
Communication channel setting time not more than 1 min
Voltage supply By alternating current 140...260V / 50 Hz
By direct current 20...72 V
Power consumption (of two half-sets) not more than 56 W