> One thing that would be good to do -- for someone who is in the
> area served by a transmitter -- rather than use «AUTO» for the
> FEC and Guard Interval values above, would be to perform a NIT
> scan on the appropriate frequencies.
>
> This should give as a result the actual transmitter frequency
> and other parameters in use, and perhaps related ones from other
> sites.
>
> These values are configured by the broadcaster and are therefore
> not guaranteed to be 100% accurate, but it is more likely that
> they know the values they are using -- these values can be used
> to locate other transmitter frequencies, as is the well-known
> case for DVB-S satellite NIT tables.
Unfortunately, the terrestrial delivery descriptors are completely
wrong in the NIT of the French terrestrial network. The NIT is the
same all over the country, which is not appropriate in a terrestrial
network, and the frequency, FEC and guard interval are wrong. The
same TS will have distinct frequencies (of course) on different
transmitters but also distinct FEC and guard interval (actually,
two combinations are used: either 2/3 & 1/32 or 3/4 & 1/8).
Recently, many transmitters have changed the modulation parameters
while staying on the same frequency. It is very difficult to keep
up to date. Between the moment when you submit a patch with the
new parameters and the moment you get the file in your distro,
the parameters may have changed again.
I think that in such a moving environment, the "AUTO" choice is
definitely better.
-Thierry
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