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Adjacent channel interface performance, Frequency stability, Digital data rates – Comtech EF Data SDR-54A User Manual

Page 64: 5 adjacent channel interface performance, 6 frequency stability, 2 digital data rates

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SDR-54A Satellite Demodulator

Revision 4

Specifications

MN/SDR54A.IOM

8.1.5 Adjacent Channel Interface Performance

The degradation in performance in terms of Eb/No shall not exceed 0.5 dB as a result of
adjacent channel interference caused by the presence of two simultaneous adjacent
channels. The channels are similar to the desired but up to 6 dBc higher in power. The
channel spacing varies as follows:

QPSK

± 1.3 x symbol clock

BPSK

± 1.3 x symbol clock

8.1.6 Frequency Stability

The frequency stability of the standard configuration is

± 15 ppm. The high-stability

option provides for a frequency stability of

± 0.5 ppm.

8.2

Digital Data Rates

The data rate (Table 8-3) for the demodulator is programmable in 1 bps steps. The symbol
rate is automatically calculated based on demodulation type and FEC coding. Any data
rate entered that exceeds data rate or symbol rate specifications will be rejected. The
demodulator is capable of supporting symbol rates from 9.6 kbps to 2.5 Ms/s. This
corresponds to data rates as follows:

Table 8-3. Digital Data Rates

Modulation

FEC

Data Rate

BPSK

1/2 Viterbi

4.8 to 1250 kbps

QPSK

1/2 Viterbi

9.6 to 2500 kbps

QPSK

3/4 Viterbi

14.4 to 3750 kbps

QPSK

7/8 Viterbi

16.8 to 4000 kbps

BPSK

1/2 Viterbi & Reed-Solomon

4.8 to 1138 kbps

QPSK

1/2 Viterbi & Reed-Solomon

9.6 to 2277 kbps

QPSK

3/4 Viterbi & Reed-Solomon 14.4 to 3416 kbps

QPSK

7/8 Viterbi & Reed-Solomon 16.8 to 3986 kbps

Note: For RS-232 data interface, maximum data rate = 64.0 kbps.









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