Bolt's crappy OTA tuners

Discussion in 'TiVo Bolt DVR/Streamer' started by Saturn, Dec 7, 2020.

  1. barnabas1969

    barnabas1969 Active Member

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    Aug 22, 2013

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    Also, if you are a "cord cutter", did you know that DECA products are available?

    DECA is equivalent to MoCA. DECA uses a different frequency than MoCA. DECA is intended for use in Satellite TV installations.

    If your primary source of "live TV" is "OTA TV", then DECA may be beneficial for you.

    DECA equipment is much less expensive than equivalent MoCA equipment.
     
  2. Saturn

    Saturn Lord of the Rings

    12,785
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    Apr 10, 2001
    I'm aware of what frequencies are used for wifi and OTA and that they SHOULDN'T interfere. The same applies to LTE, but they are close enough to cause problems in some situations.

    I have a POE filter (recently replaced with an LTE filter, which filters a superset of the POE filter) and a surge protector.

    Having one splitter for the whole house would be great, if I had multiple coax runs to each location, but I don't, so splitters must be chained together to support multiple devices on the same line. Yes, I could give up direct tuning on the TVs, but I don't think I should have to.

    I've looked at DECA (and even installed a pair of them at a business since they had coax but not CAT5 where they needed data), but it doesn't offer any sort of security and I already have a significant investment in MoCA. MoCA is further away from UHF frequencies than DECA, so I don't really see an advantage there.
     
  3. Saturn

    Saturn Lord of the Rings

    12,785
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    Apr 10, 2001
    Fingers crossed, I may have solved my issues. I made a custom antenna and put it in the backyard rather than the side yard. For now it is mounted on a birdfeeder pole.

    [​IMG]

    I used this site to make a loop tuned for 530Mhz (channel 23) which was one of the weaker ones:
    Full Wave Loop Antenna Calculator (22.8 inch loop)


    That still left channel 11 (201Mhz) pretty weak, so inspired by the Stealth Hawk design here, I added the dipole, calculated here:
    Dipole Calculator (14 inches each side)

    I used 12 AWG copper wire pulled from my scrap bin of Romex and hooked it to a balun. And then screwed it to a scrap piece of vinyl plank flooring, and secured it to the pole with a couple pipe clamps.

    It only took a little tuning (turning the whole thing a few degrees) to make sure all the channels were coming in equally - this was the most even I've ever seen this graph:
    [​IMG]

    Channel 11 is still a tad bit high (-3dBmV) but the TiVo doesn't seem to care, but it was not happy when 19 was that high - go figure. I originally had my dipole "legs" pointed downward at about a 45 degrees, but despite the digiair saying the signal was good, the TiVo didn't care for it at all and had trouble even displaying a picture. Straightening them out fixed it.

    This feeds in where my previous antenna did, though I had to take out the 10dB attenuator. Getting the antenna higher up a tree or on top of the house may get me a cleaner signal, but I don't need it any stronger. I checked all the stations I care about and they appear to be glitch-free, at least for today.

    Despite having a nice meter to give actual signal strength numbers, this still all feels a lot like voodoo.
     
    Last edited: Dec 20, 2020
    DouglasPHill likes this.
  4. mblloyd

    mblloyd Member

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    Feb 11, 2007
    Mercer...
    Unless you find that one of the previous suggestions solves your problem, you should also consider that your proximity to the transmitters absolutely requires special attention to prevent strong signals being picked up by your coax shields. A good shield connection at each connector is essential. If you are already using RG 6 coax, you might go to RG 11 and keep the "double shields" separate until you arrive at the destination. Poor connections on the coax can cause packet loses, which result is wield channel responses.
     
  5. Saturn

    Saturn Lord of the Rings

    12,785
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    Apr 10, 2001

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    All but one run of my house has RG-6, the one RG-59 is in the basement. Most if not all of the connections have been replaced with PPC EX6 ends. For the cost of upgrading my entire house to RG-11 I could probably purchase a lifetime of subscriptions to all the streaming services. :)
     
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  6. mblloyd

    mblloyd Member

    77
    2
    Feb 11, 2007
    Mercer...
    Sorry about that. I am sure that double shielded RG-11 is no cheaper now that it was 58 years ago when I was spec-ing it. The connector's price then, out of sight.

    I have been having low signal problems and was envious that you could measure your signal strength. Lo and behold, I have learned that my iPad and an app can get the incoming signal strength in dBm from my TCL RoKu TV via its IP address.

    NOTE: By various combinations of splitter, no splitter, amp, no amp, etc., on the RG-6 I was able to vary the signal strength by 11 dB. However for any given channel the Tivo showed the same signal strength regardless of combinations, or a straight through. Now I believe what is said about the TiVo signal strength meter. The TCL was spot-on with the amp and splitter dB insertion figures. But showed some variation from one splitter type to another.
     
  7. Saturn

    Saturn Lord of the Rings

    12,785
    214
    Apr 10, 2001
    So maybe not solved. The first channel that was having problems is having problems again. I now see the that digiair is reporting an SNR of 20-23dB for most stations, which is apparently not great.

    Also, SNR is the same whether connected directly to the antenna or inside the house past all the splitters and coax. So strong signal, just too much noise. When things warm up my antenna is either going up a tree or on the roof.
     
  8. mblloyd

    mblloyd Member

    77
    2
    Feb 11, 2007
    Mercer...
    I find that my Premier is very touchy about signal strength versus channel (not tuner).. What is good for one channel is either too strong or too weak for another. S/N on all channels is 20-22 dB. I can crank up and down the amp gain from -30dBm down to -49 dBm. Pixilation occurs at either end on one or another channel.
    I don’t know if this is normal TiVo performance or not. For instance, I am curious what bad power supply capacitors do in this regard. Or is there a channel frequency versus tuner effect in my TiVo case?
    Anyway, I cranked the gain up so a channel had too much signal then I added attenuation (decreased gain) until the channel with pixelation at too much signal was doing ok. I Lucked out; found a setting that worked ok for all 6 channels of interest. I cheated with the antenna rotation so the signal strength was within 2dBm across the channels of interest.
    But I don’t understand what I know from this. In a properly operating TiVo there must be a fairly wide range of signal strengths where all channels can work on any of the tuners. Why not in mine?
     
    Last edited: Jan 8, 2021
  9. Saturn

    Saturn Lord of the Rings

    12,785
    214
    Apr 10, 2001
    With just the DB4e I was getting glitching on the one VHF station. With the homemade antenna I was getting glitching on one of the UHF stations. So I've tentatively rigged up this ridiculous setup:

    DB4e on the post connected to a 10dB attenuator, going into a splitter, joined with only the dipole portion of the homemade antenna strapped to the birdfeeder to cover the one VHF channel.

    It seems to work - I haven't seen any glitching on any stations, but both antennas are still only ~4-5ft off the ground and I'm guessing my aluminum siding is wrecking havoc with certain frequencies, creating nodes, multi-path reflections, etc. I tried the dipole in the same location as the DB4e but it still glitched. I'm thinking this spring I may pick up a real UHF/VHF antenna and mount it above the roofline. I actually just mounted a weather station on a pole above our screened-in-porch. It isn't above our second story but may be a better location? The advantage is that it would still be easier to get to when necessary.

    I tried sticking the DB4e in the attic and play around with the signal meter, but it was not showing any better SNR or signal strength than 4' off the ground. And the attic is filled with blown-in fiberglass insulation - an absolutely terrible place to be messing around in.

    I also haven't found any correlation between signal strength, SNR, etc. on the Digiair that predicts when the TiVo Bolt would shows glitches. A channel can show -1dBmV with an SNR in the 24dB range and glitch every 10 seconds. Another station may show the same and be fine. A third may show -18dBmV with SNR of 19dB and be perfect.
     

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