All posts by Mike Dimmick
Below are all of Mike Dimmick's postings, with the most recent are at the bottom of the page.
george: Depends on the box.
Sky boxes will retune automatically whenever Sky change the EPG data. You may need a current viewing card inserted to get the right region, if and when ITV move some ITV1 regions.
Freesat-branded boxes are supposed to retune automatically, but not all do. Some need to be put in standby to do it, or you have to select a retune function. Some viewers found they had to do a factory reset when BBC HD and BBC One HD changed over to DVB-S2 on the same transponder.
Generic free-to-air receivers will need to be retuned manually. Don't do it until the channels disappear from their old location.
The Astra 1N satellite is in the cluster of satellites at 28.2°E. You don't have to move your dish at all.
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Nedbod: The compression will be increased to make space.
trevorjharris: The bit rate will be reduced but the BBC and the other broadcasters are happy that, with improved MPEG-4 AVC encoders, picture quality will not be.
The specification provides a toolbox for how content could be encoded, and information on how to decode it. The difficulty is all in the encoder, how it is able to process the content to most efficiently reduce the redundant data, under near-real-time constraints. Early AVC encoders were basically MPEG-2 encoders not using any of the new tools, just using a few ways of packaging the resulting stream slightly more efficiently.
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NottsUK: My assumption is that everything is still in test, with experimentation on just how much or little forward-error-correction is required, and how reliable use of 8PSK will be. 8-phase-shift keying, as opposed to quadrature phase-shift keying (QPSK), delivers three bits per symbol rather than two, but requires more signal-to-noise ratio for the same error-correcting code rate.
DVB-S2 also defines 16-APSK and 32-APSK, which require multiple amplitudes as well as changing the phase, but I wouldn't expect to see support in domestic receivers, as it's not mandatory.
I'll consider testing ended when a service is deleted from a 2A/2B/2D transponder, or an FTA service appears in the Freesat EPG.
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mrdtv: Depends who you believe. Considering I was getting the same readings percentage-wise on the digital tests as for analogue signals, I'd say it was full power, though of course the digital box isn't designed to measure an analogue signal.
If I'm right about the calibration of my box's strength meter, my usual level for low-power digital at 35% translates to 56 dBuV, while the high-power test at 60% translates to 71 dBuV, or 15 dB higher than current values. The increase at DSO is only supposed to be 10 dB. 15 dB would be near 600 kW.
BBC Two analogue was on noticeably lower power (showing only 40% on C33 on my PVR, though again measured as if it were a digital signal), which was attributed to it running from the back-up transmitter at Croydon.
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Perhaps this is the reason for the increase in capacity on ArqB. Or it could be on ArqA, as I believe the last switched-over transmitter still running Mux C is Sandy Heath, and that will change over to 64QAM 2/3 on 23 November, on its final channel and power level, according to Digital UK's postcode checker.
Either of those options would require a sub-lease from the BBC's pre-DSO Mux B capacity for the regions yet to switch (no chance they launch without London!)
Another alternative is that G.O.L.D. will get kicked off Mux A, as Top-Up TV is ulimately only borrowing Channel 5's capacity, as I understand it. TUTV aren't currently promoting G.O.L.D. as part of their subscriptions.
Channel 5 +1 is very unlikely to join the main channel on Mux 2/D3&4. The precedent is that timeshifts are not treated as qualifying services. Channel 4 +1 and all the regional ITV1 +1s are licenced under Digital Television Programme Service licences. That means that even if ITV and Channel 4 had capacity, they would have to ask Ofcom's permission to carry C5+1. ITV plc lost a slot to allow Channel 5 on in the first place; there is about one slot of spare capacity if Ofcom would get their backsides in gear and kick the remnants of Teletext off the mux, but you'd have to assume that would revert to ITV.
Of course C5 do have a regional advertising structure, which could complicate things.
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jb38: Caldbeck COM muxes are on low power until 24 October 2012, to reduce interference to the low-power digital services at Divis (Mux 1, A and B). Divis completes switchover on 24/10/2012.
Bill: You might be using a Freeview Light transmitter such as Kirkby Stephen - in which case replacing the aerial with a good quality Group A design, horizontally polarized and pointed at Caldbeck, may still produce good results. We need a full postcode to give a better answer.
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Briantist: I've recently been using BCL easyConverter Desktop BCL easyConverter Desktop — PDF to Word Converter — Accurate PDF Converter. to attack Ofcom's PDF files. It says it's PDF-to-Word but it's actually PDF-to-RTF.
I used that, along with Word's Compare Documents feature, to spot the change from Bidston to Sunningdale.
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Peter Henderson: Internationally-cleared frequencies are published in the Geneva 2006 broadcasting plan, and updates to it. The Newcastle site was cleared for 12B, the BBC national ensemble, in May 2009, and Camlough in July 2009. Camlough shows definite agreement from Ireland (and Belgium, France and Holland, since it will contribute to the overall power transmitted by the whole SFN); Newcastle doesn't, but it also doesn't show the countries expected to be affected. No-one appears to have raised a complaint, though.
http://www.itu.int/ITU-R/…g=en is updated every two weeks, though GE06 plans, covering VHF Band III for T-DAB and UHF Bands IV and V for DVB-T, are not updated every time.
In the Reserved Assignments List at Ofcom | DAB Technical Policy Documents , Camlough and Newcastle are both listed as having 'other possible local block usage' on 10C and 12D. 12D is the Northern Ireland local multiplex carrying BBC Ulster. I can't find a reference to use of 10C in Northern Ireland anywhere else, though.
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mike: Did you have digital TV before switchover? If not, you may still have a Group A aerial. For all channels from the Sandy Heath transmitter, you will probably need to change to a wideband type.
The signal levels are expected to be sufficient even with the SDN and ArqA multiplexes still on low power. ArqA will go to its final location and power level on 23 November after Tacolneston finishes switchover on that date.
If you had reliable digital reception before switchover, you should already have a wideband aerial. I'd then suspect too much signal - see Freeview signals: too much of a good thing is bad for you | ukfree.tv - independent free digital TV advice for more information.
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Wednesday 2 November 2011 1:18PM
Graham: It's quite likely that your box has tuned in ArqB from Sutton Coldfield, on C39, rather than from The Wrekin on C47. See Digital Region Overlap.
I'd second the other suggestions to remove the amplifier. It shouldn't be necessary.