7.2.10.4 The SRATE statement

The SRATE statement implements a data rate calculator which lets you convert a interface data rate into a symbol rate. This may be useful if a device driver shall supply both values, but the device itself only supports one of these settings.

The SRATE statement collects a data rate value, a modulation type, a FEC value and a Reed-Solomon factor, computes the symbol rate from this and stores the result into the destination variable. The input data for the SRATE statement may be from constants given in double quotes or from the contents of driver variables.

The SRATE statement tries to guess the conversion factors from the input data following the rules described below:

• modulation type
  • Tries to guess the modulation type from the characters the token starts with. This catches all common names for modulation types.
  • `16* : factor 4
  • 8* : factor 3
  • Q* : factor 2
  • Everything else : factor 1
• FEC
  • May be one of 1/2, 2/3, 3/4, 4/5, 5/6, 6/7, 7/8 or 8/9.
  • Everything else is treated as 1/1 (no FEC).
• Reed-Solomon factor
  • Accepts any factor written as nnn/mmm, e.g. 188/204.
  • If a single number is given, a denominator is assumed to be 204.
  • Everything else is treated as 1/1 (no Reed-Solomon)