[linux-dvb] Re: DVB-C driver (Re: More thoughts on coldboot drivercrash)

[Ragnar Sundblad <ragge@nada.kth.se>]

--On den 2 januari 2003 23:01 +0200 Jaakko Hyvätti <jaakko@hyvatti.iki.fi> 
wrote:

> Are there networks, cards, tuners or combinations of them anywhere in the
> world where the IF frequency must be something other than 36.000MHz?

I have been fiddling with the Alps DVB-T tuner TDLB7 the
last two days :-): It has a first IF of 36.166MHz.

It has a sp5659 too, but with a 10.666MHz refence which makes
the step sizes different, and a recommended step size of 166666Hz.

It uses Epcos X6966D SAW filters which have a center frequency
of 36.125MHz. I guess Alps figured that an IF of 36.166MHz matches
those better than 36.000MHz which in this case would be the
second closest step.

It seems that filters for both 36.000MHz and 36.125MHz are
common, but there are many kinds available (incl 36.167. :-).
I believe I have seen the figure 36.125MHz quite often when
looking at DVB-T stuff, I have kind of taken it as a de facto
standard, at least for 8MHz BW, like 10.7MHz or 455kHz for
narrow band radio.
A googling tells you it is quite common in DVB-C as well.
Maybe it even is a real standard.

/ragge




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