STV, Central, Yorkshire & Anglia DSO

That said, the post DSO transmissions do seem to have far more penetrating signals than their analogue counterparts. I can receive analogue from Oxford off the side of my Hannington aerial. The signals are too weak to decode teletext, and the chroma only just locks. Always been like that since we moved house 11 years ago. Since last week's DSO 1 stage at Oxford, I can now receive perfectly stable reception of the BBC Mux from there. I'm hoping from next week I'll be able to receive the HD mux, five months ahead of Hannington's DSO.

Anyone know why we don't use SFNs more for TV? I know it can't be used for relays and it can't be done across regions but it would be possible for the national MUXs or within a certain area... and would solve a lot of problems.

Incidentley, an SFN for the commercial MUXs is starting next week in the West Midlands - The Wrekin, Fenton and one other, maybe Sutton Coldfield

It's tied up with the trade off between the heavy payload we squeeze out of our DTT muxes, and the resulting short Guard Interval. It makes our potential SFN size very small, something like a maximum of 20km allowable between two or more receivable transmitters, although you can 'focus' the mush zone(s) out of harms way to an extent by offsetting the timing between Txs.



Wrekin, Bromsgrove, and Lark Stoke in fact, (PSBs already operating) though strictly speaking it's more frequency sharing, than pure SFN. The SFN effect is only valid at the overlaps between the service areas of Wrekin and Bromsgrove, and Bromsgrove and Lark Stoke. If you were to add the signal from The Wrekin, to that of Lark Stoke (possible in parts of Coventry) you'd end up with mush. (Not an issue because Coventry is served by Sutton C on different freqs)

Further reading here, 'reslfj' is a DVB tech guru !

http://forums.digitalspy.co.uk/showthread.php?p=49731759&highlight=#post49731759

The other objection to a national SFN is that existing aerials would need to be replaced with wideband models in a large number of areas.

I believe there is also resistance from the existing COM mux operators. The muxes are capable of macro regional opt outs (for advertising purposes) I don't think any regional ads exist yet, but it's a technical legacy from the OnDigital days.

What are the Emley Moor signal strengths like with such a misaligned aerial?
If they're adequate on all six muxes, why not have a group B aerial installed, horizontally polarised, to face Emley Moor as that'll get you all six muxes, whereas I guess the relay you were expecting to get is probably PSB only.

Mainly that it's a needless expense as I have Sky (having only had the four analogue channels available up to now). But I am getting all six muxes reasonably ok with the existing aerial.

Implementing SFNs from the pre DSO switchover situation would have been difficult as frequency clearing would have necessitated many retunes all over the country prior to the start of the SFN operations. The number of MUXs required, as inferred above be much more than the six most seem to believe necessary once regional variants are considered.

Replacing like with like is far easier.

Indeed. Which is why launching C5 on analogue so close to DTT (less than 18 months before) was such a poor decision.

We could have had national DTT SFNs using Chs 37 and 35 instead of C5 on analogue.

Wouldn't we have needed to have waited for 8k rather than 2k DVB-T for SFNs?

ISTR that DTT launched with 2k in the UK because the 8k variant wasn't finalised in time (or at least the chipsets weren't) ? So in reality it might have been a longer wait for SFNs to have been practical?

So after the switching of Oxford yesterday, Yorkshire and Central are now completely switched.

Interestingly some of the other transmitters in the Central region which were switched earlier this year had adjustmetnts to certain muxes yesterday too.

Even more interesting, presumably due to switchover of Oxford, adjustments were made to the commercial muxes at Mendip and a few of its relays (but not Bath) in the West region.

Now for something bizarre. I pick up from Bath relay, but I retuned anyway just as Mendip viewers were asked to do. Until yesterday I could only get BBCA (ch 25) and D3&4 (ch 2 from Bath, both almost 10 out of 10 signal quality. Suddenly yesterday I got SDN (ch 4, evidently from Mendip, albeit circa 3 to 5 out of 10 signal strength.

Yes, I believe that some transmitters had to wait until certain frequencies from Oxford were off air before they could go full power.

The Wrekin in Shropshire was one of them, it DSO'd months ago but the new commercial MUXs were on a lower power and different frequency until this week, as mentioned above it's part of a SFN with 2 others. Before DSO DTT was limited to the east as it was co-channel with another transmitter.