[linux-dvb] Some thoughts and questions

Johannes Stezenbach js at linuxtv.org
Sun Sep 30 10:27:16 CEST 2007


On Sun, Sep 30, 2007 at 06:48:31AM +0400, Manu Abraham wrote:
> Manu Abraham wrote:
> > Johannes Stezenbach wrote:
> >> 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.)
> > 
> > ACK
> > 
> > didn't account for the / K. But still for a LNB with 27 K, It amounts to around +/- 0.5MHz
> > Which is still quite small for a 5 - 10 MHz window.
> > 
> > As you said, maybe there are really bad ones with +/-1MHz drift, but i think
> > +/-3MHz is a bit too exaggerated figure
> > 
> 
> 
> http://www.satcomresources.com/SatelliteLnbs.jsp
> http://www.servsat.com/eng/htmls/lnb%20English.htm
> 
> with Prices

And compare to the prices here:
http://www.hardwareschotte.de/preise.php3?seachrange=all&searchstring=lnb
http://www.shoppingfever.de/product_info.php?products_id=271159&campaign=hardwareschotte

This is starting to get silly...


Johannes



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