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[linux-dvb] Re: tone polarity switch when stv0299 frontend is opened



Michael Glaum wrote:
I need to receive some DVB-IP data on Thor-2. I have a Hauppauge Nova DVB-s
(part # 542) that appears to have a SU1278/SH tuner and a STV0299 frontend.

I grabbed linuxtv-dvb-1.0.0-pre2. It recognized the card and with szap and
dvbnet I was able to receive my data reliably first try. It was very
impressed, it was all very logical and intuitive.

That being said, I wrote a program to set the tuner and to query the SNR, etc.
To set the tuner I called made ioctl() calls for SET_FRONTEND, SET_VOLTAGE
and SET_TONE. When I then wanted to query the SNR as soon as I opened the
frontend device, the stv0299 was reinitialized and this appears to undo my
voltage and tone settings. Specifically, the card tells the LNB to switch to
horizontal low despite the previous request for vertical low. I can certainly
get around this by leaving the frontend open after I first set the tuner but
I believe this phenomena is counter-intuitive.
You can open the frontend device readonly for monitoring purposes, see DVB/apps/szap/femon.c in the LinuxTV CVS repository.

Holger



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