[linux-dvb] Some thoughts and questions

Johannes Stezenbach js at linuxtv.org
Sat Sep 29 15:13:54 CEST 2007


On Sat, Sep 29, 2007, Manu Abraham wrote:
> Johannes Stezenbach wrote:
> > 
> > - LNBs have a constant error plus a temperature drift
> >   (e.g. +/-1MHz error, +/-3Mhz drift for a temperature range
> >   of -40 ... +60 °C -- cheap no name equipment usually worse)
> 
> This is the old LNB, the one's we use are generally based on PLL's
> have some 15 - 20k drift

If you make that 20kHz per °K then it's about the usual range
for Ku Band, maybe slightly better than average.
(An LNB with +/-20KHz drift over the full temperature range
would be ridiculously expensive.)

Don't forget that your tuner also has maybe +/-50ppm tolerance.
The errors can add up.


Johannes



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