All posts by Richard Sutton
Below are all of Richard Sutton's postings, with the most recent are at the bottom of the page.
Scan results between 09.00 and 09.30 Monday 24th April 2023.
This is then the first result with no boosters in place and both boosters unplugged from the mains:
C21: Strength 70%, Quality 100%
C22: Strength 66%, Quality 100%
C24: Strength 10%, Quality 0%
C25: Strength 34%, Quality 85%
C27: Strength 54%, Quality 100%
C28: Strength 90%, Quality 100%
C29: Strength 82%, Quality 60%
The second result with only the lounge booster in place:
C21: Strength 94%, Quality 100%
C22: Strength 95%, Quality 100%
C24: Strength 70%, Quality 0%
C25: Strength 92%, Quality 40%
C27: Strength 92%, Quality 100%
C28: Strength 98%, Quality 100%
C29: Strength 97%, Quality 34%
I couldn't see how unplugging the boosters when they were already completely bypassed by the coax cabling during yesterday's test could make any difference but I did the test anyway with both boosters unplugged and the results are the same as yesterday with the slight differences due to the slightly different atmospheric conditions.
I also did the test with the loft booster still unplugged but the lounge booster now back in circuit. These results are interesting.
The effect of just the lounge booster is essentially the same as the loft booster on the C21, C22, C27 and C28 strong signals as they continue to be very strong in both strength and quality.
However, the effect on the weak channels, C24, C25 and C29 is illuminating in that the signal strength is pretty much unchanged but the quality has reduced by around half. This suggests to me that C24, C25 and C29 are relatively dirty signals which can sometimes be made viewable by the loft booster but, if only the lounge booster is used, then the dirty signal further deteriorates on its way down from the loft such that the lounge booster, in effect, amplifies the dirt such that the boosted signal, whilst much higher in strength that the situation without any booster, is even worse in quality compared to having no booster.
The central issue is why these three signals are so weak/dirty in the first place. I suspect that C29 is not actually beamed in my direction as it is not meant for my area so we can forget about it.
C24 and C25 must be being beamed 360 degrees from the Ridge Hill mast as they are supposed to cover the whole area I believe.
There seem to me to be four rational explanations:
i) C24 and C25 are being beamed at lower power than C21, C22, C27 and C28 for some reason and are struggling to reach my aerial.
ii) C24 and C25 are located in a different physical place on the transmitter and that location is less ideal for my house.
iii) The tall conifer tree which appears to be line of sight from my aerial is filtering out the C24 and C25 frequencies to a greater extent than the others, particularly if there is a strong wind blowing and the tree branches are swaying.
iv) A combination of one or more of the above which all conspire to ensure that I will never receive C24, and only receive C25 intermittently, unless I move my home or my aerial.
Unfortunately, I only have one chimney stack so moving the aerial physically is not really viable. I could ask an installer to spin it around again and try Sutton Coldfield and see if that is better than it was 15 years ago when I last tried it but that costs me every time and might be another waste of money.
Any further ideas are welcome.
Richard
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Testing done 13.00 to 13.30 25th April 2023
First test using loft booster only on full gain:
C21: Strength 97%, Quality 100%
C22: Strength 96%, Quality 100%
C24: Strength 66%, Quality 28% (variable)
C25: Strength 74%, Quality 5% (variable)
C27: Strength 94%, Quality 100%
C28: Strength 100%, Quality 100%
C29: Strength 99%, Quality 25% (stable)
Second test using loft booster only on minimum gain:
C21: Strength 91%, Quality 100%
C22: Strength 90%, Quality 100%
C24: Strength 0%, Quality 0%
C25: Strength 46%, Quality 15% (variable)
C27: Strength 86%, Quality 97%
C28: Strength 94%, Quality 100%
C29: Strength 94%, Quality 19% (stable)
What has happened to C25? Yesterday it was reasonable but today it is unwatchable again. There is a very slight breeze today compared to yesterday's total calm but surely it can't be that?
As I'm so surprised that C24 has died completely and C25 has halved in strength but tripled in quality, I increased the booster back to full gain and took the readings again:
C21: Strength 97%, Quality 100%
C22: Strength 96%, Quality 100%
C24: Strength 66%, Quality 28% (variable)
C25: Strength 74%, Quality 4% (variable)
C27: Strength 94%, Quality 100%
C28: Strength 100%, Quality 100%
C29: Strength 99%, Quality 23% (stable)
Once again, turning the loft booster down to minimum gain:
C21: Strength 91%, Quality 100%
C22: Strength 90%, Quality 100%
C24: Strength 0%, Quality 0%
C25: Strength 46%, Quality 14% (variable)
C27: Strength 82%, Quality 98%
C28: Strength 94%, Quality 100%
C29: Strength 94%, Quality 19% (stable)
I cannot understand how signals from the same transmitter can vary from 0% / 0% to 100% / 100% at the same time.
I also cannot understand how the quality of C25 increases threefold when the booster gain is reduced from max to min, albeit it is still unwatchable, whereas C24 goes from 66% / 28% on max gain to 0% / 0% on min gain when the effect of the same change in gain on C21, C22, C27 and C28 is marginal.
As things stand, ITV4 on C25 is currently unwatchable whereas yesterday it was fine. Just to check, I did a further test with both boosters out of circuit again:
C21: Strength 82%, Quality 100%
C22: Strength 74%, Quality 100%
C24: Strength 14%, Quality 1% (variable)
C25: Strength 30%, Quality 28% (variable)
C27: Strength 62%, Quality 100%
C28: Strength 91%, Quality 100%
C29: Strength 90%, Quality 8% (stable)
Without any boosters and under current atmospheric conditions, C25 is just about watchable without any boosters although it is half the quality it was yesterday. C24 is not watchable without the booster in circuit and set to full gain and neither is C29. However, as I'm not interested in C24 or C29, I will leave things as they are, i.e. no boosters, and do the tests under difference atmospheric conditions.
Richard
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One thing that strikes me looking at these figures again is the issue of C25 ITV1 on 3 and C29 ITV1 on 800.
I do not even think that C29 is directed to my area but actually watching ITV on these channels it is immediately obvious that the picture on 800 appears to be fine but when I watch it on 3 I can see that the picture is breaking up a little every few seconds. However, when I check the signal for C29 and C25 I can see that C29 is 90% / 12% whilst C25 is 30% / 28%.
Without any boosters, I am getting a much stronger signal from the channel that I'm not supposed to be receiving and, although the quality is half of the quality from the channel that I am supposed to be using, the poor quality channel is actually giving me a better picture.
I have lived with this mess for 25 years now and have still never got to the bottom of it.
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I only have four neighbouring houses but we are all widely separated and surrounded by gardens on all sides.
Three of the four have no TV aerials and use Sky / internet and one has a vertically polarised antenna on a long pole, like mine, but pointed towards Lark Stoke. I have never tried Lark Stoke as it is not the recommended transmitter for my postcode but perhaps that was the first mistake I made 25 years ago?
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By the way, C29 has now changed to carrying just two programmes, 800 ITV1 and 803 Accessible TV Guide. ITVBe and E4+1 have both vanished overnight.
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Just to update this thread, it's a windy day today and the large conifer is swaying from side to side and the usual 4 channels are fine at 100% quality but the dodgy channels, C24 and C25, are both jumping up and down by 50% every second. C24 jumps between 20% and 70% quality and C25 between 0% and 50%.
I still have no idea why frequencies below 489 MHz or above 506 MHz do not seem to be affected by the tree but it would seem that I'm stuck with it unless I start aerial spinning again to try and find a better transmitter.
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I'm pretty sure that the problem is the tall conifer because the wind has now dropped away almost completely and C24 is now quality about 10% +/- 5% and C25 is 15% +/- 10% and are therefore much more stable than they were a few hours ago. Everything else in the house is the same as it was this morning but the previous wild 50% swings now seem to be more under control, presumably because the tree is now barely moving.
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Just to update this thread again, whilst everything in my home has remained exactly the same, the wind has varied from breezy to flat calm over the last few days but C25 has been the same reception as the strong stations with a signal strength of 95% and a quality of 100%. Reception is now perfect and this is totally the opposite end of the scale from when I started this thread a week or two ago.
C24 is still breaking up badly and seems to be unchanged signal-wise but I'm not so concerned about that channel.
I would therefore reassess my previous conclusion and suggest that the reception of C25 is not being affected by the conifer tree. As nothing has changed in my house, surely the change must either be something further away which I cannot see in the line of sight between my house and the transmitter or something to do with the transmitter itself.
Because C24 is still the same as it was, I must presume that the latter is the case and that some adjustment has been made to the C25 transmitter but not the C24 transmitter. Hopefully, the same changes will be made to C24 eventually.
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Oh well, after a few days of working at 100% quality, for the last two days it has degraded back to around 15% +/- 15% and is unwatchable again.
I have set the gain as best I can in the loft and dispensed with the lounge booster. The house does not change from day to day so I cannot see how anything in the house can be causing such massive variations in strength on one channel. It can be 100% for several days running throughout the entire period and then continuously unusable for another couple of weeks. There is nothing in the house that is switched off for several days and then switched on for several days.
When you say, "You also seem to have ignored checking for any possible sources of interference that may be especially affecting C24", I keep saying that the house is the same every day. I don't understand how I am supposed to check for interference? Nothing at all is changing in the house and there is only me here but the C25 quality is 100% one day and 10% the next so I don't understand how anything in the house could be causing this?
The booster has one input which is connected to the roof aerial.
I live in a rural setting so there are trees in all directions but the conifer is the only one that is so close that I can see that it is in the direction of the transmitter. There are no transmitters which are literally "line of sight". Even if I had a telescope and could get as high as my aerial, I do not believe that I would actually see any antenna as we are surrounded by low hills and there is no transmitter on any of those particular hills. As you would expect, Evesham is in the Vale of Evesham and all the transmitter antennas are mounted on hills which are beyond those which actually surround the vale.
The only way I could check this is to ask the installer to return. He has been here three times over the last 25 years since the house was built and each time he has spun the aerial around and checked the reception with a meter. For the first few years we thought that Sutton Coldfield was the best but there were some stations I could not watch so he spun it around to Ridge Hill which was better on some but worse on others. It's always a compromise of what I am prepared to see and what I'm prepared to miss.
Unfortunately, whilst Evesham town itself now has cable internet, we do not as none of the firms will lay a special cable just for a handful of remote homes despite dozens of requests so our internet is awful. BT say that we will have cable by 2025 so maybe I just have to wait until then before abandoning VHF.
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Sunday 23 April 2023 6:32PM
When I first bought the house I installed just the loft booster but still could not receive all the channels I was supposed to receive, although this was in the analogue days, so I installed a second booster in the lounge rather than use a passive splitter as we had three devices than needed an RF input in those days.
Installing the second boosters remedied the reception problem but the lounge booster does not seem to be needed for digital broadcasting.
The first scan was without any boosters at all, the second one was with just the loft booster and the third on was with both boosters. I didn't bother with a scan with just the lounge booster as, if you're going to have a booster, it is clearly better if it is as close to the aerial as possible.
When I say "without boosters" I mean that the cables are unplugged from the booster and then plugged directly into the wall socket/TV so omitting the booster entirely from the circuit.
Richard