[linux-dvb] fmd1216 integration

Manu Abraham abraham.manu at gmail.com
Mon Mar 12 00:51:03 CET 2007

On 3/11/07, Thomas Pinz <dc2rpt at gmx.de> wrote:
> Hi,
> On Sunday 11 March 2007 09:40, Trent Piepho wrote:
> > In dvb-pll, the frequency offset, which is the IF frequency the tuner will
> > output at, is set to 36.213333 MHz.  It looks like this code was written
> > about two years ago by Patrick as part of the reverse engineered cxusb
> > driver.
> >
> > In saa7134-dvb, there is some totally different code from programming
> > fmd1216 tuners, and it uses an IF frequency of 36.13 MHz.
> >
> > So, why the difference?
> Usually a (DVB-T) Demod has an capture area of +/- 1MHz relative to the
> programmend IF and also in most Demods the IF could be moved with certain
> register settings.
> I don't know the FMD1216, but in many designs you have a third element which
> determines the IF frequency, the SAW filter between the tuner and the demod.
> So depending on which SAW-filter you are using you choose also an certain IF.
> Epcos for example sells filters with 35.1, 35.825, 36, 36.125, 43.75 MHz and
> much more. So if you find a SAW-filter on your device, maybe have a look an
> the datasheet and you will find the right IF.
> For example, the X6872D which could be found in some DVB-T sticks, has a
> center frequency of 36.125MHz. (And 6.9MHz bandwidth)

The TU1216 's have an external SAW filter in comparison to the
internal SAW filter on the FMD1216

linuxtv.org BL my DNS for no reason, thanks to johannes for a timely fix.


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