L-Band IF Application Guide
Page L-Band - 12
6.0
Command and Control Protocol
The command and control protocol for the PSM-4900L is virtually identical to that for the PSM-
4900 70MHz IF unit. There are two new commands” shown below. The first new command
controls the BUC and the second controls the LNB.
In addition to the two new commands shown below the normal tranmsit and receive IF commands
now use 2 bytes unused in the standard unit. These two bytes extend the normal 4 byte binary
frequency number to 6 bytes.
WARNING: It may be difficult in many programming languages to generate a 6
byte number representation for binary programming of the modem.
Like the front panel controls, the remote control procedures for specifying transmit and receive IF
frequencies are dependant upon wether a BUC and/or LNB LO frequency has been supplied. If a
non-zero frequency has been input from any source then the transmit and receive frequency
becomes the RF operating frequency as described in section 2.1, “IF Frequency Range”. This
property is independent for the transmit and receive paths.
Note that the few changes relative to the standard 70 MHz unit makes it easy to use a single
monitor and control systems to talk to both modem types.
