Maghera channel 46 weaker than channel 48

BuzzG

Maghera channel 46 is much weaker than channel 48 anyone else see this ? Don't see anything on 2rn about maintenance.

TAFKAlawhec

https://www.boards.ie/discussion/2058329663/maghera-channel-46-weaker-than-channel-48

According to 2RN's homepage they are carrying out work on the site today...

Due to essential engineering work our Maghera transmitter will be subject to two 30-minute outages between 10:00 and 16:00 on Wednesday 10th January 2024.

This work will affect the Radio 1 FM service from this transmitter site.

2rn apologise for any inconvenience caused by this necessary work.

...it's not impossible that such work might affect other transmissions than advertised, though if DTT was to be affected it would be suspected that both transmissions would be equally affected.

Has this difference been the first time you've noticed this compared to the past? Considering Maghera was a former UHF Group C/D TX for analogue &digital TV up until the 700 MHz clearence, the higher frequencies will generally favour the gain on such old grouped aerials - an old UHF C/D aerial I have aimed on Truskmore gives better reception on channel E45 compared E42, for example.

dxhound2005

I am near Clermont Carn. 42 is 89%, 45 is 75%. Anytime I checked there was always some difference. It depends on what "much weaker" means.

dxhound2005

The phenomenon has been noted by different people. I contributed to this thread post #5.

https://www.boards.ie/discussion/comment/121142512#Comment_121142512

If we got more reports from people receiving all the transmitters, we could see how widespread it is.

TAFKAlawhec

https://www.boards.ie/discussion/comment/121579078#Comment_121579078

Can be various reasons for apparent differences in signal strength/quality depending on both transmitting & receiving setups - even though they are (should be) being transmitted at the same power, the two Saorview multiplexes will likely have slightly different transmission characteristics which can mean the actual ERP being transmitted in a certain direction can be slightly different. Then we get to user setups and things like higher frequencies being attenuated more on long downleads from aerial to receiver and the different gain & directivity responses from certain aerials (Yagis in particular tend have a "rollercoaster" type gain path with increases to a certain frequency before falling sharply down above the peak), not to mention potential interference from a distant transmitter that can affect the quality of one multiplex being received but not the other - in your case, another TX on E45 may be causing destructive interference to the second 2RN multiplex, but not one (or not affecting it as much) on E42. Same thing effects FM broadcast reception of the RTÉ & Today FM transmissions from the same TX aerial, making people think that one station is being transmitted with higher or lower power compared to another.

It used to be a bit more obvious in the analogue TV days especially on four-channel transmitters where often the highest or lowest frequency being transmitted often seemed to be received at least slightly worse than the other three - I used to recall Channel 4 from Brougher Mountain (E32) being slightly worse to receive compared to the other three stations on E22, E25 & E28 - similar for Carin Hill, where TG4 on E50 came in weaker than TV3 and both RTÉ stations.on E40, E43 & E46.

BuzzG

Sorry for the delayed reply .. today seeing signal level of 49 for Channel 46 and 59 for Channel 48, previously when I have checked they would be identical. Seems like this is normal and nothing out of the ordinary going by other posters observations. Thanks for all the replies.

TAFKAlawhec

https://www.boards.ie/discussion/comment/121582728#Comment_121582728

Main thing is that the signal quality from both frequencies is notably above the minimum required for successful reception/decoding - if both are, then there's not much to worry about TBF (though if you're a professional installer, it's always handy to use a 6db attenuator in place between the coax & receiver to check if both multiplexes are still being received to simulate cases where one or both frequencies are on temporary reduced power).