All posts by Briantist
Below are all of Briantist's postings, with the most recent are at the bottom of the page.
Ofcom have changed their site around a lot over the weekend and moved lots of critical data files in the process.
The radio parameters are now here - Technical Parameters for broadcast radio transmitters - Ofcom - I have changed the site code to deal with their new location.
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Brian Stanley: I've written up what is know at the current time - When will I get a new Freeview aerial because of even more mobile broadband?
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StevensOnln1: Thanks for reporting the Icomb Hill problem. It seems to have moved 10 meters to SP202228 in the Ofcom data so wasn't reponding to the SQL query using the "old" position.
It should be fixed now for you.
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nicholas: I think you might be getting things a little muddled.
Sky boxes do still use the transmission lines in the "blanking area" to fool VHS recorders' auto-levelling into making the picture dark and light. This happens only on the RF outputs.
The issue you describe "ghost outline follows the players" is actually an artefact of the MPEG-2 encoding system. A well known and fixed in MPEG-4 problem. Which is why you see it is SD that is always MPEG-2 in the UK and you don't see it on HD, which is always MPEG-4.
The MPEG-2 problem is that "motion blur" from left to right can't be compressed and causes a vast amount of extra data to be produced in the encoder. Because this will either break the bandwidth limit or buffer size, the encoder has to ditch some of the detail. Most of the time this is imperceptible live, but the moment you give people the ability to pause and live-rewind, it is more obvious.
The effect is even worse on lower horizontal-resolution channels (on Freeview) such as ITV4.
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technical data on the above - MOTION ESTIMATION
IN MPEG-2 VIDEO ENCODING USING A PARALLEL BLOCK MATCHING ALGORITHM Motion compensation - Wikipedia, the free encyclopedia Motion Estimation How To Avoid MPEG-2 Conversion "Motion Streaking"
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John: Interesting.
The maps have been designed to allow you to see both town/city/village names and the roads. Other details has been turned off. I've just visually checked the above map and I can see the places and roads quite well...
You might find the maps on the prediction page more useful as you can change the selected transmitter. https://ukfree.tv/prediction and use your postcode.
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StevensOnln1: The problem seems to be the data is missing from the Ofcom data - which is listed on Technical Parameters for broadcast radio transmitters - Ofcom and links to https://www.ofcom.org.uk/….csv .
You might like to tell them and then the data will appear on here again! Contacting Ofcom - Ofcom
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As far as I know, the move to clear the 700MHz band from Freeview doesn't require the change of the existing services to DVB-T2. It may also be possible to continue the "interim multiplexes" com7 and com8 in what is shown as the "centre gap" C55/C56 (using a UK-wide single frequency network) beyond the introduction of the mobile services - however Ofcom have said in the linked document above that they aren't planning to do this.
I've been though the whole document and there is no suggestion **at all** that the existing PSB and COM multiplexes will change to DVB-T2 before June 2020.
However, once com7/com8 close down (at the end of May 2020) there might be pressure to switch other multiplexes to DVB-T2 to increase capacity and move to having HD for the public service channels (those of the BBC, plus ITV (1), Channel 4 and Channel 5).
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Friday 7 October 2016 3:50PM
P. Kieran Ward: Thanks. Normally Akismet: Spam Protection for WordPress removes all these posts before they ever appear. This seems to have been missed! I've banned the user, as you suggested.