My Humax Forum » Freeview HD » FVP 4000T, 5000T

Signal Quality Issue Since Dec on 1 Channel Only

(5 posts)
  1. davidrew

    davidrew

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    I have a 5000T and since the Freeview signal problems at the end of December, due to the high pressure and inversion, channel 55 (COM7 HD) has never fully recovered its original 100% signal quality. It is now usually at 10% but fluctuates from no signal at all to 80%.

    I am on the Oxford transmitter, which is 14 miles direct with a clear line of sight. The Humax is attached via a Labgear LDA2061LR 6 Way Distribution Amplifier which has the Class 3 4G filter. The aerial is a SLx Digidome mounted in the loft and is powered from the Labgear. As I have a strong signal a SAC AE5199DC variable attenuator is on the cable between the wall and the Humax to reduce the strength.

    C Channel S: Strength Q: Quality
    C:29 S:79 Q:100 COM4
    C:31 S:80 Q:100 COM6
    C:37 S:76 Q:100 COM5
    C:41 S:87 Q:100 PSB1
    C:44 S:76 Q:100 PSB2
    C:47 S:87 Q:100 PSB3
    C:51 S:53 Q:10 LOX
    C:55 S:72 Q:10 COM7 HD
    C:56 S:72 Q:100 COM8 HD

    Nothing has changed in the setup and I have checked all the Freeview WEB sites and there is no engineering works or reported faults.

    I know channel 55 and 56 are due to be decommissioned sometime this year but it is a bit annoying when BBC News HD (107) goes no signal.

    Anyone else with a similar issue in Oxfordshire, or any ideas.

    Thanks

    | Wed 29 Jan 2020 12:47:44 #1 |
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    A1944

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    That the strength is the same as Ch 56 suggests to me that it may be some kind of interference. It could be coming from an HDMI cable in your setup. Try moving any HDMI cables as far as possible from aerial cables.

    | Wed 29 Jan 2020 13:31:10 #2 |
  3. grahamlthompson

    grahamlthompson

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    davidrew - 53 mins ago  » 
    I have a 5000T and since the Freeview signal problems at the end of December, due to the high pressure and inversion, channel 55 (COM7 HD) has never fully recovered its original 100% signal quality. It is now usually at 10% but fluctuates from no signal at all to 80%.
    I am on the Oxford transmitter, which is 14 miles direct with a clear line of sight. The Humax is attached via a Labgear LDA2061LR 6 Way Distribution Amplifier which has the Class 3 4G filter. The aerial is a SLx Digidome mounted in the loft and is powered from the Labgear. As I have a strong signal a SAC AE5199DC variable attenuator is on the cable between the wall and the Humax to reduce the strength.
    C Channel S: Strength Q: Quality
    C:29 S:79 Q:100 COM4
    C:31 S:80 Q:100 COM6
    C:37 S:76 Q:100 COM5
    C:41 S:87 Q:100 PSB1
    C:44 S:76 Q:100 PSB2
    C:47 S:87 Q:100 PSB3
    C:51 S:53 Q:10 LOX
    C:55 S:72 Q:10 COM7 HD
    C:56 S:72 Q:100 COM8 HD
    Nothing has changed in the setup and I have checked all the Freeview WEB sites and there is no engineering works or reported faults.
    I know channel 55 and 56 are due to be decommissioned sometime this year but it is a bit annoying when BBC News HD (107) goes no signal.
    Anyone else with a similar issue in Oxfordshire, or any ideas.
    Thanks

    Check the DTG reception predictor detailed view. COM 7 and COM 8 are in the process of moving to a Single Frequency network. If that has happened and you happen to be in the mush zone that could explain why if another adjacent transmitter now uses the same channels for Com 7 and Com 8.

    | Wed 29 Jan 2020 13:44:05 #3 |
  4. davidrew

    davidrew

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    Posts: 273

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    Thanks for the suggestion Graham.

    I have checked and the Hannington transmitter (35 miles away) also uses Channel 55 and 56 for COM7 and COM8 with no offset the same as Oxford. the only difference is that Hannington transmits these at higher power than Oxford. CH55 36.7KW vs. 16.4KW, C56 26.2KW vs. 17.1KW.

    For my postcode the signal checker shows variable reception for both 55 and 56 from Hannington so I suspect you are correct and I maybe in the 'mush zone' or the Humax has picked up the wrong transmitter for channel 55.

    As they are on the same channels a manual retune will be useless as I still won't know which transmitter I'm picking up. What I will try is to block the existing channel 55 signal by turning up the attenuator, make a note of the schedule, then do a full retune and see if 55 comes back.

    | Thu 30 Jan 2020 0:42:25 #4 |
  5. grahamlthompson

    grahamlthompson

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    davidrew - 9 hours ago  » 
    Thanks for the suggestion Graham.
    I have checked and the Hannington transmitter (35 miles away) also uses Channel 55 and 56 for COM7 and COM8 with no offset the same as Oxford. the only difference is that Hannington transmits these at higher power than Oxford. CH55 36.7KW vs. 16.4KW, C56 26.2KW vs. 17.1KW.
    For my postcode the signal checker shows variable reception for both 55 and 56 from Hannington so I suspect you are correct and I maybe in the 'mush zone' or the Humax has picked up the wrong transmitter for channel 55.
    As they are on the same channels a manual retune will be useless as I still won't know which transmitter I'm picking up. What I will try is to block the existing channel 55 signal by turning up the attenuator, make a note of the schedule, then do a full retune and see if 55 comes back.

    It may be a guard interval issue on the Hannington or other transmitters transmitter. I get my signals from Lark Stoke which is part of a SFN network with the much closer Bromsgrove transmitter. I lost my signals for around 2 weeks and it turned out to be a guard interval issue on the Bromsgrove relay. A local aerial fitter might be aware of the issue.

    A larger more directional aerial with a narrower forward lobe might help or a antenna with a large rejection of rear signals . Again a local company might be able to help.

    Alternatively talk to Justin at ATV aerials. He actually tests the aerials he sells personally.

    His website has a wealth of knowledge;

    https://www.aerialsandtv.com/site-contents

    http://www.telecomabc.com/s/sfn.html

    | Thu 30 Jan 2020 10:11:41 #5 |

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