Datum Systems PSM-500L Bedienungsanleitung PDF herunterladen (Seite 30)

Datum Systems PSM-500, 500H & 500L VSAT/SCPC Modem Specification

Rev. 0.86

A-30

Link Calculation Example:

A modem with R-S and IBS mux is running at a user rate of 128 kbps with rate ½

FEC and no buffer. The Reed-Solomon is set as example 1 above: The IBS multiplexer is set

to 2400 bps ESC Overhead and 300 bps MCC Overhead yielding a Mux ratio of 29/30.

The channel bit rate is then = 128 kbps X 9/8 X 30/29 = 148.9655 kbps. (Note 9/8 is n/k.)

The time/channel bit is 6.7 uS. The time/user bit is 7.8 uS.

The modulator delay is 13 channel rate bits x 6.7 uS plus 906 user rate bits x 7.8 uS

plus 500 uS, for a total delay of 7,653.9 uS or 7.65 mS.

The demodulator delay is 185 channel rate bits x 6.7 uS plus 3638 user rate bits x 7.8 uS

plus 500 uS, for a total delay of 30,115.9 uS or 30.116 mS.

The total end to end delay is then 37.766 mS plus the approximate 250 mS for the path delay.

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Datum Systems PSM-500L Bedienungsanleitung Seite 30