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P300H P300 Series Modem Installation and Operating Handbook Page 26
BER performance with
concatenated RS BER improvement depends on n and k values chosen, but a typical
increase in coding gain of 3dB is possible over basic Viterbi mode.
Monitor Functions Measured FEC input BER (raw channel, not TCM)
Estimated FEC output BER (not TCM)
Measured Reed-Solomon input BER
Estimated Reed-Solomon output BER
Measured deframer FAW BER
Measured Eb/No (not based on channel BER, range: 3.0-15.0dB,
accuracy ±0.2dB).
Measured frequency offset (± 100 Hz resolution)
Clocking and Buffering
Clock Loops Frequency locked loops give phase hit immune operation even with poor
clock sources such as routers etc.
Tx Clocking Internal Reference (see Internal Reference below for stability)
External - tracking range ±100 ppm / min.
Rx Timing - slaves Tx internally generated timing from Rx clocking
whatever Rx clocking mode is selected eg with Rx=Satellite for loop
timing (with full asymmetric rate capability), or with Rx=Station for
both Tx & Rx clocking slaved to Station Clock (again with full
asymmetric rate capability).
Rx Clocking Clock from satellite (Buffer disable)
Transmit input clock - (plesiochronous, includes full asymmetric rate
operation)
Internal Reference (see Internal Reference below for stability)
DCE External timing clock (DTE interface only).
Station reference (see below)
Internal Reference P300: +/-1PPM
P310: Default as per P300. Options: 7x10-7 per year (P313B), 1x10-7
per year (P313C), 7.5x10-8 per year (P313D).
Station References inputs 75
BNC female, transformer isolated 1MHz to 10MHz in 1kHz steps
(accepts sinusoid >0dBm or squarewave eg G.703 para 10)
120
RS422 compatible input, 1kHz to 10MHz in 1kHz steps
When set to 10MHz, the station reference may replace internal reference
to all internal circuitry (eg IF synths). The unit automatically switches back
to the internal reference if the station reference fails.
Buffer Size Selectable in 1 ms increments from 0 to 99 ms. Automatically adjusted
to slip an integer multiple of terrestrial multiframe length for framed rates
(T1/E1).
Buffer storage is 32kBytes, so above 2.6 Mbps max buffer size reduces
linearly from 99 ms to 52ms at 5.0Mbps