On Friday 23 December 2011 18:27:12 Patrick Boettcher wrote:
> On Friday, December 23, 2011 02:38:59 PM Andreas Oberritter wrote:
> > On 22.12.2011 22:30, Antti Palosaari wrote:
> > > @@ -201,6 +205,9 @@ typedef enum fe_guard_interval {
> > >
> > > GUARD_INTERVAL_1_128,
> > > GUARD_INTERVAL_19_128,
> > > GUARD_INTERVAL_19_256,
> > >
> > > + GUARD_INTERVAL_PN420,
> > > + GUARD_INTERVAL_PN595,
> > > + GUARD_INTERVAL_PN945,
> > >
> > > } fe_guard_interval_t;
> >
> > What does PN mean in this context?
>
> While I (right now) cannot remember what the PN abbreviation stands
> for, the numbers are the guard time in micro-seconds. At least if I
> remember correctly.
Totally wrong.
The number indicated by the PN-value is in samples. Not in micro-
seconds.
To compare the PN value with the guard-time known from DVB-T we could do
like that: in DVB-T's 8K mode we have 8192 samples which make one
symbol. If the guard time is 1/32 we have 8192/32 samples which
represent the protect the symbols from inter-symbol-interference: 256 in
this case.
In DTMB one symbol consists of 3780 samples + the PN-value. Using the
classical representation we could say: PN420 is 1/9, PN595 is about 1/6
and PN945 is 1/4.
HTH,
--
Patrick Boettcher
Kernel Labs Inc.
http://www.kernellabs.com/
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