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All posts by Michael Perry

Below are all of Michael Perry's postings, with the most recent are at the bottom of the page.


John O'Flaherty:

The predicted reception at your location is shown as being good and reliable. It is therefore likely that you have an aerial feed problem. That is not i=uncommon and is known to cause loss of or disruptions oif just one channel. So please check all your aerial cables and connections, where there are coaxial plug/sockets unplug then and then refit (that is to clear any possible corrosion/oxidation on the contacts) and then check that you are correctly tuned to the Limavady signals, go to http://www.digitaluk.co.uk/coveragechecker/main/trade/BT48+8AF/NA/0/ and scroll down to the Limavady listing and use the current channels listed there. It will also tell you what the future changes may be and roughly when.



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Colin Sharp:

Yes it could have been. The aerial would have fed the VHS recorder directly and the output of that fed to a distribution splitter, which may have provided some amplification to bring all the signals to the same level, and thence to each of the sockets. Note that an active splitter is not the same as a signal amplifier. in splitting the signal feeds there is always some loss involved and an active splitter provides enough amoplification to recover the signal levels at each output to roughtly the same as it would have been without the signals being split. On the other hand, an aerial amplifier is mounted as close to the aerial as possible and amplifies an already weak signal. If the signal is not weak, then no amplifier is needed. In your case it seems that you need an active splitter and not an amoplifier. Please check whether the device you are calling an 'amoplifier' is either an amplifier or an active splitter - looking up the product name/part number will help.

It would help if you provided a full post code so that we contributors can look at the predicted reception conditions at your location and hence determine whether you need any amplifier at all.



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SteveK:

Firstly you have too much signal as 99% will cause overload of the tuner as the received signal level varies as it does all the time. That could be causing your system to be uncertain whether it is receiving 1080p or 1080i services.

I am not aware that there is any 'switching' happening as it does not change on my system fed from Mendip.



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Naseem Shafi:

Aerial system problems are well known by technical people to affect different frequncies differently and at different times. That is what's appears toi be happening with your system affecting the ARQB services.



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Chris SE:

I am very well qualified as I spent 50 years working in the TV inductry in technical roles, as a Senior Technical Trainer for a large TV rental company before moving to similar roles in other related companies. I also have a Masters Degree in Electronics and Physics. So I am very well qualified to make the comments I do based on both technical knowledge and understanding as well as relevant experience.

Further, you miss the point that we do not know what equipment is being used by the person reporting a problem. So we need a general approach unless a specific question is asked. Further, due to the varying attenuation by the atmosphere we do not know how much their signal varies, as it does on every receiver, so we need to give guidance in such a way as to avoiud the overload conditions whilst still meeting the minimum requirement levels needed by tuners.

I know of instances where a 90% signal strength gives intermittent problems. My younger brother, also an electronics engineer with higher degrees, was suffering from just such a problem and when we checked the strength it was in the 90% range and varying. So a 3dB attenuator was fitted, reducing the signal levels to 84% on most multiplexes and that cured the intermittent sound problem. A family friend was having problems with apparent loss of some channels. All the usual checks were made of the aerial system and the only feature visible was the strength being 96% on the worst affected mux. A 6dB attenuator solved that with a signal strength now showing as 86%.

You asked why I and others so often quote the 60%-85% range, they are examples of why. You assumed I didn't know what I was talking about so I have now corrected your understanding.

QED.



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Full technical details of Freeview
Thursday 18 October 2018 10:48AM

Chris:

I am glad we seem to be making progress. You surmise that a side lobe of the very high gain aerial is receiving unwanted signals is quite likely. However, just turning off the amplifier tunrns it into a high loss attenuator wioth much reduced signal feed. It would be better to take it out of circuit, even if only temporarily, and coupling the two coaxial cable ends together with a coaxial coupler, very inexpensive, so the signal is fed through in full. Worth a try?



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Rob:

The last engineering work carried out at the Sudbury transmitter was on 1st August 2018, no other work has been done since.

It is worth checking your aerial system to ensure that all the cabling is in good condition and that all joints are in good order. If there are coaxial plugs/sockets then unplug those and refit them to clear any possible corrosion/oxidation from the contact surfaces.

If you have access to another Freeview TV then use that to check that your aerial system is working correctly.



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Rowridge (Isle Of Wight, England) transmitter
Friday 19 October 2018 11:06AM

Jeff Allen:

No recent work is listed fro Rowridge. Could it be that your aerial has moved in the recent very strong winds? It needs to be pointing at 220 degrees and be a wideband type. Also check all your aerial cables are in good condition and that any joints are also in good condition. If there are coaxial plugs/sockets present then unplug those and refit to clear any possible corrosion/oxidation from the contact surfaces.



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