Silicondust needs to re-think its treatment of duplicate Virtual Channels, as the existing implementation is VERY POOR. Here in SF Bay Area, there is main Sutro Tower (SF landmark) transmission tower, BUT ALSO South Bay Repeaters for extending coverage to South Bay. Fox 2, NBC 11, and ABC 7 all have South Bay Repeater. Fox 2 (KTVU) illustrates the problem.
KTVU employs an overlapping virtual channel footprint that is improperly handled by Quatro (et al.) tuners. The Sutro Tower signal (Physical Channel 26) is just strong enough (e.g., Quality = 45%, Strength = 45%) that it interferes with reception of the South Bay repeater (Physical Channel 31), because the SD tuner improperly locks onto it (despite the Repeater signal having FAR BETTER Strength/Quality). The problem is KTVU has both Sutro Tower and South Bay Repeater on the SAME virtual channel 2.1 and unfortunately the Silicondust Quatro tuner does NOT handle the scenario correctly (generically: situation where an antenna is located somewhat between two transmitters using same Virtual Channel).
In my particular case, the Silicondust tuner when instructed to tune to Virtual Channel 2.1 locks onto the Sutro Tower Physical Channel 26 instead of South Bay Physical Channel 31, but Physical Channel 26 is way too weak (e.g., Quality 45%) for sustained viewing. There is NO WAY to override this at the tuner to instruct it to tune to the "other" Virtual Channel 2.1 (which has 82% Strength/100% Quality). The SD tuner is selecting the (far) weaker signal 100% of time so its built-in program logic to handle this scenario is uniformly ineffective/defective, supporting the case that user override should (always) be an option.
On the broadcaster side, NBC 11 avoided this problem altogether from the outset by putting their South Bay repeater on a separate VIRTUAL channel (i.e., 11.3 instead of 11.1), but both Fox 2 and ABC 7 using overlapping duplicate virtual channels. Although a given broadcaster can avoid the problem like NBC did, the TUNER manufacturer SHOULD have avoided this being a problem in the first place by allowing the user to optionally specify channel selection by Physical Channel when faced with duplicate Virtual Channels, or at least have solid program logic to make ABSOLUTELY SURE the tuner rarely locks onto a (substantially) weaker signal when faced with duplicate Virtual Channels. In SD tuner's case, SIMPLY list the duplicate Virtual Channels in the Channel Lineup page so that the user can de-select any interfering weaker channel.
My only currect option is to de-tune Sutro direction (which has OTHER 1000 mW signals I do need) just enough to force Sutro Virtual 2.1 from achieving tuner lock (which currently locks out ONLY usable Fox 2 signal).
Reception, channel detection, network issues, CableCARD setup, etc.
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I have a similar issue in Harrisburg, PA market with the NBC affiliate having 3 different signals that I can reach (main and 2 repeaters) that are on different real channels but use the same virtual channel. My TV's tuner will list the two virtual channels separately whereas the SD tuners only pick one.
[MOD EDIT: constructive criticism is fine, but please don't be rude - NS]