All posts by Chris.SE
Below are all of Chris.SE's postings, with the most recent are at the bottom of the page.
Richard Sutton:
Hi. Interesting results. As you say, It seems whatever is causing problems on C24 is having a marginal effect on C25.
But, you never mentioned you had a "lounge" booster as well!
Were both boosters powered OFF when you did the first scan?
Was the Lounge booster powered OFF when you did the 2nd with only the Loft booster in place?
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Richard Sutton:
So they were not disconnected from the mains then which was another important factor.
You are correct in that it's always best to have any booster nearest the aerial.
There is no need to retune now as you are correctly tuned.
Could you please repeat the test with no boosters and BOTH disconnected from the mains.
Then, as it might help with diagnosis, could you do a test with just the lounge booster in circuit but remember the loft one remaining out of circuit and disconnected from the mains.
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Ted Slater:
Hi, yes it would annoy me too! I wouldn't expect Quest to have any answer, this is undoubtedly down to some quirk or fault with the Humax Aura 4k PVR on the assumption that when you do the full reset the tuning memory is completely cleared - were you able to/did you check that before retuning again?
Is it still the same LCN TV Channels numbers or is it common to one multiplex (COM6?).
I would have expected Humax to have come up with an explanation, how old is the box?
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Graham Seward:
There is also other information about C29 which is unclear. An OFCOM document which supposedly lists all the transmitters, channels and powers after the 700MHz Clearance programme (which I know to have a number of errors) states C29 is 20kW which is no doubt where this site got its information. Yet the Freeview Checker (DUK sourced) says it's 2kW. Which is correct is difficult to be certain, but I'd guess 2kW is more likely to be correct given the modulation type, as those signals will travel further on lower power as a consequence. Most Local multiplexes on the main transmitters that have them use QSPK modulation as well.
Given that Malvern is Vertical polarisation (Ridge Hill being horizontal) might mean any twiddling with aerial position or even aerial type may change your situation but is not predictable, it'll be a case of suck it and see, and whether it's something you can do yourself, or would otherwise be very costly.
I'm not sure if a radiation pattern for C29 is available. When I have a moment I'll have a hunt to see what I can find, if there is something, then your approximate location or full postcode would help to see if there's any chance of you getting anything.
Richard Sutton will be affected to a degree by Malvern but I'd expect in the main for it to just be a lower quality figure and as long as it's not too low it should be watchable.
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Richard Sutton:
Hi. Right. The reason for powering off the equipment is to check that those items themselves are not generating interference. They can go faulty, become unstable etc etc. So the latest tests show that if the C24 problem is interference, it's not originating from your boosters.
As for causes, you can forget (i) and (ii). AFAIK based on official documents & other information that I can find, they on the same antenna. C29 however isn't. As mentioned above I'll see if I can locate any radiation pattern. However the PSBs (C28, C25, C22) are 20kW, COMs 4/5/6 (C21, C24, C27) are 10kW but I wouldn't expect that to make any significant difference to you (a few % maybe on strength).
(iii) Well that is a possibility but I'm surprised that we don't see any variation in signal on the other frequencies when it's wet and windy, so can't conclude that this is the primary cause.
(iv) Very unlikely for the reasons given for the above.
If you can't do it yourself, obviously moving/changing aerials would be expensive and may result in no benefit. Not something to seriously consider just yet IMHO.
Interference is still a strong possibility and also one needs to consider the strange possibility of there still being some signal overload issues!
Looking at all the figures, you don not need the Lounge booster, it's certainly a recipe for overload as any strength figures of 100% make that a possibility. Also as the strength figures drop slightly without it, and quality figures seem to generally be better overall, this again shows it's not needed.
The effects of overload can vary from set make/model to set make/model, so just to be certain we don't have any oddities, there something else we can try. Leave tuning as it is, I'd expect C29 Quality to be "variable" because of the probable interference from Malvern.
OK, loft booster only in place and active. As it has a variable gain control, turn it down a bit. To start with turn it down so that the 90%+ figures drop to 80-85% keeping an eye on Quality figures which should remain at 100% apart from most likely C24 (& C29).
Leave it set like that for a while and post the figures.
Then see how stable they remain for a period of time, say post back after the first 24hrs then after a few days unless you see significant variations in the interim.
The other factor to try and investigate is interference - much more tricky. I think you mentioned there were only four of you in your postcode, how close are they?
Which transmitter do they use, do they get a similar issue with C24 if they use Ridge Hill?
Do they have any older devices like VCRs, Game consoles etc that might have an RF output set around C24?
Your own electronic equipment including LED and Discharge (eg. fluorescent, sodium etc) lighting.
Try switching these things off (remove/unplug from the mains, not just standby conditions) to see if there's any change in C24 Quality.
HTH.
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Graham Seward:
Richard Sutton:
Information update on C29. During the 700MHz Clearance, on 1 March 2018 when COMs 7&8 moved to C55&C56, D3&4 West changed modulation from 64QAM to QPSK and reduced power from 20kW to 2kW. As previously mentioned the change in modulation with the lower power results in pretty much the same coverage. No sign of a radiation pattern yet though.
The Malvern transmitter (then serving ~57,000 households) started on the 7th March 2018.
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Richard Sutton:
Hmm, interesting. Yes see how things change over the next 24hrs. Based on what you've seen so far I'm thinking tweaking the gain somewhere in between to get a more consistent quality on C25 & C27 as I don't think we are into overload conditions, unless there's some interference that's saturating things. The cause could be the trees or interference, especially seeing C27 slightly affected.
Try and investigate this potential interference issue now. As mentioned see what neighbours experiences may be. Also consider things like a nearby street light or similar that may even be on 24/7.
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Richard Sutton:
I wouldn't call any particular choice of transmitter necessarily a mistake. Predictions are what they are, based on typical aerial heights of 10m, but obviously cannot take into account any local obstructions like trees or tall buildings etc. and what you get on the spot can be different.
Your neighbour would need a tall pole because the terrain gives a local obstruction on the line-of-sight to Lark Stoke. However it may still have been the only option because there maybe trees or buildings on the LoS to Ridge Hill or Sutton Coldfield making the signals from them far more unreliable, have a look and see what things look like. It would still be a weaker signal than an unobstructed signal from Ridge Hill.
Out of interest, check how your aerial points (use a compass on a smart phone?). It's 253 degrees for Ridge Hill, 8 degrees for Sutton Coldfield, 101 degrees for Lark Stoke (V) but often slight tweaking is needed for optimum signal.
Try and check the interference possibilities but in view of what you've seen today, I'm suspecting the trees could be the issue. Trees can affect a narrow band of frequencies, not just by obstructing a signal but producing multipath distortions, even polarisation changes! Whist DTV is generally very good at coping with multipath, sometimes just the wrong position/distance from trees can have a serious effect, but never the less it would be a good idea to try and ensure interference isn't a likely cause.
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Graham Radford:
That's an odd one, not heard of any similar issues anywhere (yet?!).
With the BBC ONE HD updates and the other four channels changes it's possible somewhere might have had hiccups.
Try a further TV channel Clearance, and if you can manage it, try a manual tune of each of Tacolneston's UHF channels C40, C43, C46, C42, C45, & C39, that's in the multiplex order BBCA/PSB1, D3&4/PSB2, BBCB HD/PSB3, SDN/COM4, ArqA/COM5, ArqB/COM6.
There's a Local multiplex is on C32 but whether you receive it will depend on your location as it's beamed towards Norwich.
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Saturday 22 April 2023 7:35PM
Jim:
if you are near the Village Surgery whose postcode I did a quick check for, you should get the BBC National DAB multiplex 12B also a Commercial Local multiplex Block 12A: 223.936 MHz which carries BBC Radio London, and another one on Block 11C: 220.352 MHz which carries BBC Radio Kent.
As an aside you should have no trouble getting the two National Commercial multiplexes
D1 on Block 11D: 222.064MHz
SDL on Block 11A: 216.928 MHz