Block A Channel

Reception, channel detection, network issues, CableCARD setup, etc.
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NOYB
Posts: 202
Joined: Thu Dec 12, 2013 2:12 am

Block A Channel

Post by NOYB »

Is there a way to block a specific channel signal so that it is not picked up by scans?

The situation is that VHF 12 is also broadcast in a nearby community on low power UHF 18 and I have to manually configure WMC to use VHF 12 (including half dozen sub channels). Normally scanning is not a frequent occurrence but there is quite a bit of channel changes going on and upcoming. VHF stations changing to UHF, low power stations being displaced and having to change...

NedS
Silicondust
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Re: Block A Channel

Post by NedS »

NOYB wrote: Mon Jul 19, 2021 11:13 am Is there a way to block a specific channel signal so that it is not picked up by scans?

The situation is that VHF 12 is also broadcast in a nearby community on low power UHF 18 and I have to manually configure WMC to use VHF 12 (including half dozen sub channels). Normally scanning is not a frequent occurrence but there is quite a bit of channel changes going on and upcoming. VHF stations changing to UHF, low power stations being displaced and having to change...
In other words, block by frequency, not by virtual channel number? At the moment, I don't believe we have this option.

NOYB
Posts: 202
Joined: Thu Dec 12, 2013 2:12 am

Re: Block A Channel

Post by NOYB »

Right. By frequency.
Didn't think the capability existed. Thought I'd ask just in case.

Came across something about short circuiting a stub tuner to notch out a channel. But that is probably beyond me to design. Maybe could build if I knew exactly what to build.

Thanks

ebo
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Device ID: 1016F746, 101C8CF9, 1041F134, 10532394
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Re: Block A Channel

Post by ebo »

I have the same problem except that I don't use WMC. I've dealt with it in various ways. One is to add an attenuator when doing a rescan such that the channels you want are still strong enough to be recognized in the scan but 18 isn't. Then remove the attenuator when the scan is done. Actually I use a variable attenuator so I don't have to remove it, just reset it to minimal attenuation.

If WMC uses the Digital Antenna.xml file that was needed for SD's legacy tuners (usually C:\ProgramData\Silicondust\HDHomeRun\Digital Antenna.xml) then you can use a text editor to either delete the channel 18 entries (497 MHz) or comment them out by adding <!-- at the start and --> at the end. If you use Notepad++ as your editor, it shows the commented-out sections in green. If WMC makes its own file and you can find it, you might be able to edit that.

I use CW_EPG which has the option to see the RF channels as well as the virtual ones and I don't map the channel 18 subchannels to the Schedules Direct listings for that station. But I also still use SD's old HDHomeRun QuickTV which shows both broadcasts and only the virtual channel. That's why I used to delete 18 from Digital Antenna.xml but now I've added "-18" to the call sign so I can tell them apart. I don't know what if any effect that would have on WMC.

Code: Select all

  <Program>
    <Name>WNYT-18</Name>
    <Modulation>8vsb</Modulation>
    <Frequency>497000000</Frequency>
    <TransportStreamID>2113</TransportStreamID>
    <ProgramNumber>3</ProgramNumber>
    <GuideNumber>13.1</GuideNumber>
    <OriginalNetworkID>0</OriginalNetworkID>
  </Program>
  <Program>
    <Name>MeTV-18</Name>
    <Modulation>8vsb</Modulation>
    <Frequency>497000000</Frequency>
    <TransportStreamID>2113</TransportStreamID>
    <ProgramNumber>4</ProgramNumber>
    <GuideNumber>13.2</GuideNumber>
    <OriginalNetworkID>0</OriginalNetworkID>
  </Program>
  <Program>
    <Name>startTV-18</Name>
    <Modulation>8vsb</Modulation>
    <Frequency>497000000</Frequency>
    <TransportStreamID>2113</TransportStreamID>
    <ProgramNumber>5</ProgramNumber>
    <GuideNumber>13.3</GuideNumber>
    <OriginalNetworkID>0</OriginalNetworkID>
  </Program>
  <Program>
    <Name>getTV-18</Name>
    <Modulation>8vsb</Modulation>
    <Frequency>497000000</Frequency>
    <TransportStreamID>2113</TransportStreamID>
    <ProgramNumber>6</ProgramNumber>
    <GuideNumber>13.4</GuideNumber>
    <OriginalNetworkID>0</OriginalNetworkID>
  </Program>

Watcher
Posts: 18
Joined: Thu Apr 08, 2021 10:38 pm

Re: Block A Channel

Post by Watcher »

NOYB wrote: Mon Jul 19, 2021 11:13 am Is there a way to block a specific channel signal so that it is not picked up by scans?

The situation is that VHF 12 is also broadcast in a nearby community on low power UHF 18 and I have to manually configure WMC to use VHF 12 (including half dozen sub channels). Normally scanning is not a frequent occurrence but there is quite a bit of channel changes going on and upcoming. VHF stations changing to UHF, low power stations being displaced and having to change...
Looking at this from a trivial RF physics perspective for a digital tuner scanner, and you do not need too precise of the cutout, "Band reject", "band stop", or "notch filters" are readily available at reasonably prices (a UHF 14-19 filter is in the range of $20-$40). If you need a single channel notch filter (leaving UHF 17 and/or UHF 19 tunable), the prices go up substantially.

jasonl
Expert
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Re: Block A Channel

Post by jasonl »

Where do you find filters like that with F connectors? I see plenty of them with SMA connectors for SDR setups, but finding filters for things other than LTE with F connectors is difficult these days.

Watcher
Posts: 18
Joined: Thu Apr 08, 2021 10:38 pm

Re: Block A Channel

Post by Watcher »

jasonl wrote: Thu Jul 22, 2021 5:54 pm Where do you find filters like that with F connectors? I see plenty of them with SMA connectors for SDR setups, but finding filters for things other than LTE with F connectors is difficult these days.
Channel Plus offers band-stop filters (typically blocks a 5 or so channel range (as you know, that makes the filter cheaper)) at somewhat reasonable prices:  (sample item https://www.summitsource.com/Linear-NF- ... 10069.aspx which might even work for the OP). The typical issue is finding a source for the specific range you may need, as most sources available to the public are for specific well known purposes. Multiplex Technologies Inc appears to be the source (Channel Plus is just the branding).

For more precise (i.e. single channel band-stop with adjacent channel pass) Tin Lee http://tinlee.com is one of the well known providers with a good reputation (but the
pricing reflects the target audience).  There is an ebay seller from slovakia who will do custom filters too: https://www.ebay.com/usr/jan_jenca although I have no personal experience.

And, of course, one can design/build their own filter.

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