On Tue, Mar 16, 2010 at 4:22 PM, Kyle Lil <[email protected]> wrote: > Interesting. It looks like the error rate is ~1 per 25 minutes with qam_gain > set to 0x01 and the weak SNR (0x140). With the qam_gain set to 0x02 and the > weak SNR (0x13c), the error rate is back to ~2 per minute.
Ok, so you described the behavior with the weak SNR. What about with the strong SNR? > So it seems that the error rate is more related to the qam_gain setting than > the SNR. Without knowing the behavior with a strong SNR, I cannot confirm or argue against this conclusion. It's possible that you will see the opposite behavior with a strong SNR (where you get fewer errors with the gain set to 0x02). > I was > actually just taking a shot in the dark by changing this parameter. Could > you tell me what it actually does? Is this related to AGC gain somehow? Not without both of us having a degree in applied signal theory. :-) It's a tuning value for controlling the gain when in QAM mode. On the mxl5005s it is typically set based on the selected target frequency. However, because of the combination of the mxl5005s and the s5h1409 as well as some nuance of the PCB layout of the HVR-1600, it's always hard-coded to 0x02. Basically, by hard-coding the setting to 0x02 (instead of making it frequency dependent as per the mxl5005s datasheet), we duplicate the behavior in the Windows driver (the engineers at Hauppauge arrived at that conclusion after using equipment significantly more expensive than what's in my budget). I keep asking about the error rate and effects of changing the gain relative to the SNR because I'm wondering whether there is some optimization I can put in there where I base programming of the the gain level on the final SNR. Devin -- Devin J. Heitmueller - Kernel Labs http://www.kernellabs.com _______________________________________________ ivtv-users mailing list [email protected] http://ivtvdriver.org/mailman/listinfo/ivtv-users
