Comtech EF Data CDM-625, Инструкция по установке и эксплуатации

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Chapter 12. ESC++
12.1 Introduction
The ESC++ mode of operation is a new closed network frame structure which combines
A
utomatic
U
plink
P
ower
C
ontrol (AUPC) with a high speed asynchronous order-wire channel.
The AUPC works identically to that offered with EDMAC and D&I++ framing, but is not
compatible with either. This is because ESC++ framing uses a different overhead percentage than
the other closed network framing modes.
12.2 Overhead Details
Baud rates from 1200 to 38400 bits/sec are offered using RS-232 format. As with the main
remote port (P4B), three data formats are available: 8N1, 7E2 and 7O2. Pins 5 and 6 of P3A are
the input and output, respectively, for this data channel. Because 38.4 kbaud is the maximum rate
available, the actual overhead percentage for ESC++ framing changes as the data rate increases,
thereby saving bandwidth at high data rates. The added overhead is as follows:
Data rate Overhead ratio (percentage)
64 kbps to < 768 kbps 19/17 (11.76%)
768 kbps to 1.5 Mbps 12/11 (9.09%)
> 1.5 Mbps to 2.5 Mbps 29/27 (7.4%)
> 2.5 Mbps to 7 Mbps 19/18 (5.56%)
> 7 Mbps 64/63 (1.58%)
Note that 64 kbps is the minimum data rate allowable with ESC++. Depending upon code rate
and modulation used, the modem’s maximum data rate of 25 Mbps may be used with ESC++. In
all cases, if the Reed-Solomon outer codec is used, the 126/112 ratio is employed with ESC++.
The new frame structure may be used with any FEC codec type available with the CDM-625.
12–1