User's Manual

13
PROGRAMMING
Narrowband FEC
Narrowband FEC sets the forward error correction rate in the narrow bandwidth modes of 1.25 or 2.5
MHz. The two rates available are 1/3 and 2/3; the normal default setting for good quality video is 2/3.
Changing the FEC rate to 1/3 will extend the receiver sensitivity by 2 to 3 dB at the expense of degraded
video quality and longer latency.
Narrowband Guard Interval
Narrowband guard interval is used in the narrowband modes of 1.25 and 2.5MHz to adjust for varying
multi-path delay conditions. The default is 1/16 however 1/8 can be selected if necessary to deal with
extreme multi-path delays on long links. Selecting 1/8 guard interval could cause a degradation in video
quality and latency.
Narrowband Modulation
Narrowband modulation is used in the narrowband modes to select between QPSK and 16QAM
modulation. For best range with good video quality, QPSK is used; 16QAM will give better video quality
but will cut down the link range by approximately 50%.
Unit Name
The Unit Name is the index for each configuration. It is only transmitted, however, for Narrowband and
Ultra-Narrowband modulations. (In DVB-T, Provider Name or Service Name can be used to uniquely
identify the device.)