Chapter 13. Esc; Introduction; Overhead Details - Comtech EF Data CDM-600 Installation And Operation Manual

13.1

Introduction

The ESC++ mode of operation is a new, closed network frame structure which combines
Automatic Uplink Power Control (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.
In order to use this feature, Firmware Version 2.0.1 (or higher) must be installed.
13.2

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
64 kbps to < 768 kbps
768 kbps to 1.5 Mbps
> 1.5 Mbps to 2.5 Mbps
> 2.5 Mbps to 7 Mbps
> 7 Mbps
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 20 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-600.

Chapter 13. ESC++

Overhead ratio (percentage)
19/17 (11.76%)
12/11 (9.09%)
29/27 (7.4%)
19/18 (5.56%)
64/63 (1.58%)
13–1