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DOCSIS Head Transceiver

Docsis-transmitter-2.jpg AntDocsis.jpg

A DOCSIS transceiver is intended for arrangement of an over-the-air Internet network. It is installed near a combined antenna and is connected with drop cables to a head cable modem (CMTS), for example BSR-1000. The connectors "INPUT"/"" and "OUTPUT"/"" are connected correspondently to the CMTS forward and reverse channel connectors. A supply voltage of +30...+45V is applied over a central core to the connector "INPUT"/"". The connector "ANTENNA"/"" is connected to the antenna with a circular antenna diagram. Quantity of subscribers in the over-the-air network is defined by CMTS performance capabilities and can reach 1000 and more. Data transmission rate to the subscribers of an over-the-air Internet network is up to 37 Mbit/s, data reception rate from subscribers is to 8 Mbit/s (the data are given in case of using a CMTS Motorola BSR-1000). The area coverage radius while having a combined antenna with Gain = 12dB and a subscriber combined antenna is 24dB: for a QAM256 - 8km (with a store for weather conditions of 10dB), for a QAM64 - 32km (with a store for weather conditions of 10dB). Data rate while using a QAM256 - 37Mbit/s, a QAM64 - 27Mbit/s.
Combined Antenna TA-DOCSIS (price 990 nominal dollars). It is intended for operation with the DOCSIS head transceiver. Reception frequency 2300-2320MHz, transmission frequency 2500-2530MHz, SWR<1,5, gain=12dB, horizontal polarization, circular pattern.

Specification of Transmitting Device
Frequency range of output signal arriving to antenna 2.5 - 2,524 GHz
Rated-output power 0.3 W
Frequency range of input signal from CMTS (of forward channel) 0.470 - 0.494 GHz
Input signal power (APM system operation) -27...-2 dBm
Heterodyne oscillator frequency 2,030 GHz
Heterodyne oscillator frequency departure under the influence of all destabilizing factors not more ± 3 kHz
Out-of-band emission level not worse -60 dBc
Short-term heterodyne oscillator frequency instability not more 10 Hz ...
Heterodyne oscillator phase noise while tuning out to ± 100 kHz not worse -100 dBc/Hz
Third degree intermodulation product when output power of each of the two signals is 0.14W not worse -50 dBc
"INPUT" Input resistance 75 Ω
"ANTENNA" Input resistance 50 Ω
APM System depth not less ± 10 dB
Voltage supply/Power consumption +30...+45V / 39 W
Readiness time after turning on does not exceed 5 min
Ambient temperature -30...+50
Relative air humidity up to 100%
Operation mode continuous
Weight 3.5 kg
Dimensions 240x190x105 mm
Specification of Receiving Device
Frequency range of input signal arriving from antenna 2.305 - 2.325 GHz
Frequency range of output signal arriving from CMTS (of a reverse channel) 28.0625-43.0625 MHz
Gain 30 dB
Noise ratio 5 dB
Heterodyne oscillator frequency 2.276937 GHz
Heterodyne oscillator frequency departure under the influence of all destabilizing factors not more ± 3 kHz
Short-term heterodyne oscillator frequency instability not more 10 Hz
Heterodyne oscillator phase noise while tuning out to ± 100 kHz not worse -100 dBc/Hz
Selectivity over image channel not less 50 dB
Third degree intermodulation product level when output level of each of the two signals is 101.dB/µV not worse -45 dBc
Ambient temperature -30...+50
Relative air humidity up to 100%
Operation mode continuous
Transmitter signal suppression (2.5-2.524 GHz) by receiver input filter is not worse 50 dB

Worsening of SNR in the "DOCSIS transmitter-DOCSIS subscriber receiver" system (in comparison to the "head CMTS modem-subscriber modem" system) is ~3dB (38dB are instead of 41dB for a QAM 256 in the forward channel).