TIMTER™ Multi-mode Digital Telemetry Transmitter
67
Quasonix, Inc.
If the transmitter includes the LD option (but not LD6)
, then LD 0 or LD 1 are used to disable or enable LDPC,
as shown in the example immediately following. With the LD option, the block size and code rate are always 4096
2/3.
Examples:
LD
Show the current encoder state
LD 1
Enable the LDPC encoder
LD 0
Disable the LDPC encoder
If the transmitter includes the LD6 option
, the user may select from the six implemented LDPC codes. This also
allows user selection of the CCSDS randomizer using the RA or RN command. Adding LD6 automatically enables
the existing LD option.
The IRIG standard calls out six variants of LDPC codes—all combinations of two different information block sizes
(k=4096 bits and k=1024 bits) and three different code rates (r=1/2, r=2/3, and r=4/5).
LD6 Code
Block Size and Code Rate
0
k=4096, r=1/2
1
k=1024, r=1/2
2
k=4096, r=2/3
3
k=1024, r=2/3
4
k=4096, r=4/5
5
k=1024, r=4/5
With the LD6 option, use LD 0 or 1 to disable or enable LDPC, then use 0-5 to indicate the desired LDPC code. A
space is required between the disable/enable code and the desired LDPC selection, as shown in the examples.
Examples:
LD 0
Disable the LDPC encoder
LD 1 2 Enable the LDPC encoder and set the block size and code rate to k=4096, r=2/3
LD 1 5 Enable the LDPC encoder and set the block size and code rate to k=1024, r=4/5
4.2.1.1.12 Overtemperature Control
– OC
OC is the overtemperature control enable command. When enabled (set to 1), if any transmitter temperature (digital
board or PA) goes above a set limit stored on the device, and the current power level is over 25, the transmitter
automatically starts to back off power in 2 dB steps to a max of 6 dB.
Contact Quasonix for the default overtemperature value specific to your transmitter.
4.2.1.1.13 RF Output
– RF
RF enables or disables the RF power output from the transmitter. A 1 enables the output and a 0 disables it. If no
parameter is entered, the current state displays.
