Matthias Schwarzott wrote: > On Freitag, 17. Oktober 2008, Devin Heitmueller wrote: >> Hello, >> >> In response to Steven Toth's suggestion regarding figuring out what >> the various units are across demodulators, I took a quick inventory >> and came up with the following list. Note that this is just a first >> pass by taking a quick look at the source for each demodulator (I >> haven't looked for the datasheets for any of them yet or done sample >> captures to see what the reported ranges are). >> >> Could everybody who is responsible for a demod please take a look at >> the list and see if you can fill in the holes? >> >> Having a definitive list of the current state is important to being >> able to provide unified reporting of SNR. >> >> Thank you, >> >> Devin >> > >> mt312.c unknown > > The hardware provides two values: > * AGC: For now the AGC feedback value (14 bit) is returned unchanged. > * ERR_db: Also available is a 10-bit value representing the signal level > difference between AGC-Reference and received signal level (most likely in > 1dB steps). > > If an absolute value is needed: I don't get it how to calc absolute signal > levels from AGC-Reference. > > so code for now: > mt312.c: agc-feedback 0-0x3FFF > > @Obi: > Any additions? >From the manual: 7.2.3 Measured Signal to Noise Ratio. Registers 9 - 10 (R) M SNR[14:0]: These two registers provide a indication of the signal to noise ratio of the channel being received by the MT312. It should not be taken as the absolute value of the SNR. Eb/N0 = ~ (13312 - M_SNR[14:0] / 683) dB. The equation given only holds for Es/No values in the range 3 to 15 dB, i.e. Eb/No values in the range 0 to 12 dB. Regards, Andreas _______________________________________________ linux-dvb mailing list linux-dvb@xxxxxxxxxxx http://www.linuxtv.org/cgi-bin/mailman/listinfo/linux-dvb
