Thanks Chris.SE.

I know that Com7/8 have a considerably lower than the other mixes, but I was specifically wondering if their power output reduced from some higher level on 4th Sept? That would explain my (and many other's) sudden loss of signal. If they've been at their current power level for some time then the reason must related to the / shift instead.

As an aside, is there any official way to complain or raise a query about this? Who would this be directed to?

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Divis (Northern Ireland) transmitter
Saturday 14 September 2019 12:25PM

Thanks so much Chris.SE. What is the plan for the that currently reside on com7/8 when they close down? I actually like some of them!

I haven't changed anything, but am now able to receive and tune com8 on Ch 60, albeit with pretty variable , but get nothing on com7 on Ch 51.

I used an SDR dongle as a very rudimentary spectrum analyser, and I am receiving an 8MHz wide signal that is centred around 714MHz, which corresponds to Ch 51. In terms of raw received power it is actually comparable to the other muxes, but as you suggest it must be getting scrambled with as all of my devices read 0 signal quality and are unable to tune it. I'm not sure that there is too much I can do about that.

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Divis (Northern Ireland) transmitter
Thursday 10 October 2019 1:52PM

Thanks for the detailed info Denis. I'm a couple of miles and line of sight from , so I couldn't understand what was going on. In case it helps anyone else I have now solved my tuning problems. It turns out the problem was...my flyleads!

I have 3 flyleads in series - one from the socket to a surge suppressor, from the suppressor to my PVR, then another from the PVR to the TV. The ones to / from the PVR came with it.

My problem was that at the TV I was getting a zero strength reading for Ch 51 (com7) while Ch 60 (com8) was intermittently reading either 0 signal strength or occasionally 30-40%, but very poor .

I mentioned before that using a basic spectrum analyser showed that I appeared to be getting decent signal peaks at the appropriate frequencies, so I didn't know what was going on. However, I was only testing this at the end of the flylead from the wall socket. Doh!

A few nights ago I noticed that when I accidentally touched and moved one of the flyleads to / from PVR I suddenly briefly received better on Ch 60. Wondering if they were faulty I then replaced both PVR flyleads with a couple of homemade ones I put together from WF100 I had lying around. After replacing one, Ch60 signal strength improved to around 60%, and after replacing the second I now have a signal strength of 80+% on Ch60 and 50+% on Ch51, both with 100% signal quality!

The old flyleads were typical of those you get with devices like PVRs. They weren't that thick, but didn't appear particularly cheap. Their connectors appeared alright too. I'm not sure if they had a really poor response and were overly attenuating higher frequency , which became noticeable when the Com7 / 8 muxes moved up to Ch 51/60, or if they just have very poor shielding and were picking up lots of at those frequencies. In any case, replacing them with good quality, well shielded cabling has completely solved my problem and was relatively quick and easy to do. Worth considering if anyone else has similar problems.

Thanks to all those here who contributed advice / information.

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Divis (Northern Ireland) transmitter
Tuesday 22 October 2019 1:19PM

Denis:

I'm about 4 miles from the . I have an old mounted Labgear (I think) 12-element Yagi. It's about 1.3m long. It might be overkill for my location, but it provides enough strength for me to passively split it four ways without problem. I've never actually tried a set-top aerial here.

The USB dongle I use for SDR is a NooElec NESDR Mini 2+. It has an R820T2 tuner and cost me about 20 from eBay if I recall. Software-wise I use SDR# on Windows, Spektrum as a spectrum analyser and Gnu Radio and rtl-sdr on Raspberry Pi / Linux, along with ADS-B and DVB-T2 decoders depending on what I'm doing.

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