Comtech-ef-data SDM-2020 Manuale Utente Scaricare il pdf (Pagina 177)

SDM-2020 Satellite Demodulator Revision 4

G.703 Data Interface MN/SDM2020D.IOM

11–11

11.1.5.5 Buffer Centering

The unit provides buffer centering capability. The operator via the front panel can set the

buffer to 50%. Buffer centering also occurs automatically after each of the following:

receive signal acquisition, change in buffer size, change in buffer reference, and an

overflow/underflow condition. During overflow or underflow conditions a Demod alarm

is indicated. A buffer full condition is reported when the buffer exceeds 90% full, or

when the buffer falls below 10%.

11.1.5.6 General Receive Specifications

Refer to Table 11-10 for general RX specifications.

Table 11-10. General RX Specification

RX 2047 Pattern

Generation

The unit supplies a 2047 test pattern substitution into the RX data path

and performs BER calculations on that pattern, with the results reported

to the host unit.

AIS/Data Fault Detection The unit provides AIS (all 1’s) or data fault (all 1’s or 0’s) detection on the

incoming RX data stream.

RX AIS Assertion The unit provides AIS substitution into the RX data path when

commanded by the host unit.

RX Output Stable The unit provides data stable (all 1s) into the RX data path when

installed in a unit RX data stable shall be removed when either interface

loopback or interface loop-through is turned on.

Buffer Reference Clock

Activity

The unit provides activity detection for RX Satellite Clock, TX Terrestrial,

and External Clock sources. An alarm condition is communicated to the

host unit when lack of activity is detected.

RX Buffer PLL Fault

Detection

The unit provides RX Buffer PLL fault detection. When the RX buffer PLL

is not locked a fault condition is communicated to the host unit.

FPGA Program Error

Detection/Reporting

The unit detects TX and RX FPGA programming errors and reports

errors to the host unit.

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Comtech-ef-data SDM-2020 Manuale Utente Pagina 177