All posts by Owen
Below are all of Owen's postings, with the most recent are at the bottom of the page.
Chris:
Thanks for the reply, solving the confusion with the main Info on this page.
It seems the main change was a move of C51 to C33, and I believe this may have happened late last year, as I was then able to get channels listed on that COM4 Multiplex for the first time and presumably was part of the 700MHz clearance plan. With C56 now being removed for other reasons and C55 to eventually.
I assume which Freeview channels are on which Muliplex is still basically the same?
(Although there have often been some shuffles in the past, so it would be good to know exactly where they are on this particular Transmiiter and not usually documented on other websites)
It's a pity that C48 looks like it will stay up there on its own long term, as it's just under 700MHz, and so quite a bit higher than the C21-C36 range of the others (which only need a Group A aerial).
I did originally buy a Group W antenna, to cope with all future changes, but I'm not convinced it works too well at upper end as I've never been able to get C48 or ones in the 50's
- despite C48 being basically as high a power as the others that are OK most of the time.
I might have to try one of the newer group T ones, to see if the narrower response / reduced top end gives a more consistent response.
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Chris.SE:
However, the Analogue transmission power levels were around 5x / 6dB higher, so there was more margin against interference. And analogue receivers were more tolerant to reduced signal levels, degrading more gracefully and just showing noise / interference on the picture.
Whereas with the digital system, a slight-drop in signal level (particularly for those on the margins of reception, as a decent more-local transmitter is not provided for our area) can just result in no reception at all - as I've had for many periods this year (The worst since switchover, and presumably due to sunspot cycle peak), as well as last few days.
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Chris
Thank you for the info.
I did recall that in the Analogue days - with the same aerial - that it was rare for reception to go completely / be totally unwatchable. I was used to a poor Ch5 one, as had to swing aerial round to Oxford, as Sandy Heath's analogue Ch5 was 20dB down at only 10kW ERP.
I'm still using a Group W wideband aerial, as until recently that was the best one to have, being as some of the extra multuplexes were placed at the top of the UHF Band, when Sandy Heath was originally a 'Group A' only lower-channels area.
But have considered trying the narrower 'all-band' group T, now that upper frequencies are no-longer used. A group K is still a bit too narrow, to cover all of the current multiples from Sandy Heath.
The Dallington Park relay is only 40W! And I'm right at the edge of the coverage map. So local terrain will likely to be just as much of an obstacle as signals from Sandy Heath (Which I can receive most multiples from, most of the time).
Also, Dallington Park is 'Freeview Light' rather than full freeview. So only carries 3 of the multiples, so wouldn't get all of the channels from that, either.
I think if I can get my aerial a few feet higher, into the loft (or ideally outside, although in theory aerials are not allowed outside due to a - widely ignored - original Builder's Covenant!), then that may gain enough extra dB's of signal / reduce off-direction signals to be much-more resilient to interference.
I do recall, that the 48-element Yagi wouldn't even pick up any Analogue channels when initially tried downstairs, before DSO. Whereas a small loop / telescopic aerial would receive thse OK, about 10miles further South of here. So does indicate how marginal reception is here / importance of getting aerial up quite high, to lessen obstructions.
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Chris,
Thank you for your update 'correction' over this.
Despite the 700MHz clearance apparently being completed by Sep 2020 - So max frequency that should have been used was 694MHz (Ch.48) - it seems COM7 etc still carried-on, operating on channels above 48, on some transmitters after this.
However, I've now found out that this apparently finally-ended in June 2022.
Although, strangely, group T aerials are still being sold by many DIY places
- with them only stocking that (originally 'universal' group replacement for group W) group T.
And, even more strangely, some aerial manufacturers still appear to be making group T aerials (as well as group K), such as: 48 Element F-Type High Gain Aerial Group T | Blake Aerials - Blake UK
So it seems no-one has told them there's now no point in having a Group T aerial!
And in-fact it could be much worse than using a group K one (of which some have Low Pass Filters to reject signals > Ch.48), as you could then be picking-up more 5G interferrence in future!
Therefore, it looks like getting a decent Group K aerial, and hopefully that will improve things, if it help to reject unwanted frequencies, and also hopefully the in-band performance on a bit-narrower band should be flatter / more likely to be better directivity and less pick-up from the sides at band edges.
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Friday 26 June 2020 2:18AM
Is the channel / frequency list for this transmitter now slightly out of date?
- As I get Freeview Ch.12 Quest etc. on TV Ch. 33 (570MHz), which isn't listed fr this transmitter.
I'm fairly sure I am getting this from Sandy, as it is as strong as all the other Sandy Heath channels 24, 27 & 36 that I can receive in a rather marginal coverage area of Northampton.
So I can't get anything on TV ch.51, if COM4 / SDN is actually still there (The How TV channels change over time only goes upto 2014, although it seems it was originally planned for this to go at the end of this month - but not sure where the Freeview channels on this multiplex would move to)
TIA