On Tue, Dec 1, 2009 at 6:33 AM, Andy Walls <[email protected]> wrote: > On Mon, 2009-11-30 at 23:41 -0800, Jeff Campbell wrote: >> Hello All, >> >> I was using the ATSC tuner side of the HVR-1600 over the weekend and I >> had a hard time determining my signal strength or finding a place >> where I can get a consistent SNR reading that can be used to compare >> the relative strength of the various channels I am able to tune. What >> is the recommended way to determine signal strength and SNR? > > I'm sure Devin has a lot more details than I, but you can look at the > output of femon. Keep the following in mind: > > 1. The status is coming from the s5h1409 module, the driver module for > the ATSC/QAM demodulator > > 2. The signal strength is bogus. From the code it looks like a copy of > the SNR. > > 3. The SNR value will only be valid when there is a lock. Don't count > on it otherwise. > > 4. Since Steve Toth wrote the driver, I'm assuming the SNR value is in > 0.1 dB, but I'm not sure. > > > That of coure still doesn't give you what your margins are for good, > bad, and marginal for 8-VSB, QAM-64 and QAM-256. I suppose one can look > up the theoretical BER vs SNR curves to find out. > > That's actually one status output I would like: SNR margin. The > absolute values don't mean much to people.
Everything Andy said above is correct. If you have any further questions that Andy's response didn't answer, feel free to ask. Devin -- Devin J. Heitmueller - Kernel Labs http://www.kernellabs.com _______________________________________________ ivtv-devel mailing list [email protected] http://ivtvdriver.org/mailman/listinfo/ivtv-devel
