On Friday 08 May 2009 22:47:15 Andy Walls wrote: > On Fri, 2009-05-08 at 21:58 -0400, Nick Nobody wrote: > > On May 8, 2009 08:04:11 pm Andy Walls wrote: > > > On Fri, 2009-05-08 at 16:56 -0400, Nick Nobody wrote: > > > > Hello, > > > > > > > > I just got a HVR1600 and am trying to build a channels.conf file with > > > > all the channels that I get using my TV (it has a built-in ATSC > > > > tuner). > > > > > > Are you using the cx18, mxl5005s and s5h1409 drivers that came with > > > your distribution or the latest v4l-dvb repository drivers? > > > > > > If not the latest, you should try those first. See the cx18 page on > > > ivtvdriver.org for instructions on getting the latest drivers. > > > > > > http://www.ivtvdriver.org/index.php/Cx18 > > > > > > > I use the following command to scan for channels (on mythbuntu 9.04): > > > > > > > > scan /usr/share/dvb/atsc/us-ATSC-center-frequencies-8VSB > > > > > > > > It manages to find every single channel except for WFFF-TV (aka > > > > FOX44). My television shows that it has a strong signal strength and > > > > is actually better than some other channels. > > > > > > According to the FCC, WFFF-TV's digital station is on UHF channel 43. > > > How does WFFF's analog station look on UHF channel 44? Any snow, > > > ghosting, or interference lines? > > > > > > If so, that indicates poor reception from that transmitter. If so, > > > also please review: > > > > > > http://www.ivtvdriver.org/index.php/Howto:Improve_signal_quality > > > > > > > Is there something I can do help the scan program > > > > find this channel? > > > > > > Well, if it helps, the center freq for an ATSC-8VSB channel on UHF > > > channel 43 is 647.028615 MHz. > > > > > > Maybe you could make up a manual entry in channels.conf, azap to it, > > > and then use femon or dvbtraffic to see if you can get a lock and see > > > the PIDs in use. > > > > > > Where I'm at, PIDs 0x31 (49) and 0x34 (52) are usually in use for the > > > primary video and audio program. > > > > > > > I noticed that it's one of the few (or only) channel that > > > > broadcasts in 720p instead of 1080i, but I doubt that makes much of a > > > > difference... > > > > > > It shouldn't make a difference. > > > > > > Regards, > > > Andy > > > > > > > Thanks, > > > > > > > > nick > > > > Hi Andy, > > > > Thanks for the quick and detailed response. > > > > It seems that you're right about it being a signal strength issue because > > as soon as the sun went down I was able to (unreliably) find the channel > > with a scan. > > That can happen when the main beam of your antenna (or a sidelobe) is > pointed at an an object in the sky with a high noise/brightness > temperature (the sun or the galactic disk). When that bright object is > seen by your antenna, the noise degrades the signal to noise ratio. > > You may want to focus on steps to reduce noise: gounding the coax shield > to reduce EMI and adding a low-noise preamplifier. > > > I've gone through all of your recommendations and here's what I've come > > up with: > > > > Using the latest drivers makes it much harder for me to get a lock, I had > > better results with version 1.0.4 that comes with the vanilla 2.6.29 > > kernel (I'm using the prepackaged 2.6.29 ubuntu kernel: 2.6.29-02062902). > > That's surprising. AFAIK, there was possibly one change to the s5h1409 > driver to make it tune faster, by reseting the digital demodulator's > tracking to help it lock on to the new signal faster. You may just have > good luck with the old driver by being tuned to a certain station before > going to WFFF. > > > 44 is just snow for me, but I'm assuming that's because their analog > > transmitter is off-air. All the wiring is new, in fact there's only one > > splice (union) from the antenna down to the capture card. > > OK. Please ensure you're using a splitter and not a splice; as a > splitter is needed to match impedences properly. Also make sure you've > got a grounding block (connected to green wire ground) in the coaxial > cable as close as possible to where the coaxial cable attaches to the > antenna to ground the shield of the coax. Reducing EMI made a big > difference for me. > > > As mentioned above, I was able to get a lock tonight and was able to > > watch the channel for a good 25min but then it just crapped out. Is there > > a way to increase the sensitivity of the card? > > I don't have data on the MXL5005s tuner nor the data on the discrete > components wired up to it. Without that, I have no hope of tweaking the > mxl5005s configuration to make the reception better. :( > > > I personally use a low noise (2.9 dB NF), high gain (29 dB) VHF/UHF > preamp from Winegard for my home. It's an AP-8275: > > http://www.winegard.com/offair/preamp.php > http://www.winegard.com/kbase/upload/chart29.pdf > > It works great for me, because I live so far from the city. The 29 dB > gain can overdrive tuners (and thus degrade reception), if you live > where signals are of decent strength, so a low-noise preamp with less > gain is better in most situations. > > > My television (which has a much longer > > length of wire going to it) has a perfect picture day or night; I don't > > understand why it works while the HVR1600 doesn't :S > > Have you tried connecting the HVR-1600 to the wire feeding your > television? > > Regards, > Andy > > > Thanks for your help, > > > > nick >
Everything is grounded properly and I'm using the same coax everywhere (75 Ohm, RG-6, 95% shielded, rated for 2200MHz). I'm using a splice at the moment to reduce any potential loss that I might incur from using a splitter (only one device is connected at a time). This will eventually be replaced with a splitter once I get everything sorted. Right now the HVR-1600 is working properly, I can get FOX but I suspect that it's because it's night time. I'll report back in the morning once the sun comes back out. One thing that I don't understand is how come the television reports that it's getting such a high signal strength (about 75%, and I still get a picture all the way down to about 30% while turning the antenna) while the capture card can't get a lock (I can't verify what the signal level is on the capture card because femon -H always reports "signal 0% | snr 0%"). Are all ATSC capture cards this picky? I swapped out the cables and nothing changed, I wish it was that simple :( Thanks for your continued help, nick _______________________________________________ ivtv-users mailing list [email protected] http://ivtvdriver.org/mailman/listinfo/ivtv-users
