So you're saying that Ofcom just decided suddenly one day that the GMG mux should be QAM16? Come on, what's the likelihood of that? It's much more likely that GMG asked Ofcom, who then approved it (or they just went ahead and changed it; I don't know exactly what the rules are about that). Which still means it's their fault that the coverage has gone much poorer. There's a general rule of thumb that, with a few very small exceptions, you should make sure that anyone who can receive a mux at a given point in time should always be able to receive that mux or the equivalent. This has obviously been broken by GMG. It should be clear to anyone that changing to QAM16 would reduce their coverage, yet they went ahead and did it anyway, before changing power.

Like your relationship to Arqiva? It's quite obvious you work, or have worked for them.

You obviously know more about Channel M's finances than I do. I'd assumed when you made all but 3 of your staff redundant, you didn't have any money sloshing around for capital projects. I doubt they're diverting much of the Guardian's funding to keeping a tx on a hill alive.

Oh but I am. I just think it's hard to take someone seriously when it seems like they pay no attention to what they write. If somebody can't be bothered to check the simple stuff, why should I believe them when they talk about more complex matters?

Sorry, that's incorrect. My trig isn't what it used to be, but where I live in north Manchester the difference in pointing my aerial between the top and bottom of the mast would be less than one degree, I'm fairly sure this is well within the vertical beam width of my aerial. Even the aerials on houses in Horwich seem to be parallel to the ground, not pointed up into the sky.

The top would be the optimum place if you wanted people in Glossop to have a standing chance of picking up your signal. However a cost-benefit analysis would probably indicate the extra households covered don't justify the additional cost. I do agree that co-location of 'sites' is important.

I'm sure sticking an aerial 50 feet up Crystal Palace or Sutton Coldfield wouldn't work. But we aren't talking about those sites. What I'm talking about is specific to Winter Hill.

Here's where your lack of experience shines through. The business case for something like this will be a trade-off between coverage/robustness and capacity. The bean counters will have chosen capacity, and since the bean counters are always in charge, that's what they've done.

Besides, the licence is technology neutral, they have no requirement to cover any specific area. If they're making money, then there's no issue. Now the licences for Local TV are likely to be different, but we aren't talking about those here.


Check the planning documents, specifically the median templates, you'll see how over-cautious Arqiva have been in the planning of this.

If you think for one moment that Arqiva (assuming they think they're going to be MuxCo) are going to use QPSK you're even more naive than I thought. They'll milk these muxes for all they're worth, if that requires them to fiddle the planning docs to run them 64QAM, they will. They'll turn a tidy profit that won't be fed back into local TV.

Like I said before, it'll be the bean counters.

So more profit for Arqiva and no carriage revenue for the local services, what a great plan, you should get into politics because you certainly haven't got any business acumen.

More opinion masquerading as fact, that's your trademark isn't it? It's only incorrect because you don't agree with it. Maybe it's time to get off that armchair and offer your services as a technical consultant?

There are no rules, the licence is technology neutral.

When you say rule of thumb, you mean a rule that you've just invented? I don't recall any document from Ofcom stating such restrictions.

Like I said in my previous post, if they're still covering the areas that are profitable for them, then there's no issue. Remember, they ran 16QAM from launch for over a year before they went to QPSK for a few months. The increased coverage obviously didn't result in increased revenues.

I agree with the above poster.(FrankieRay). Height will only push the transmitter horizon further. The main problem is an adjacent channel at the same location pushing out 100kW. Not to forget also the Llandonna transmitter on the same channel beaming into Manchester approx 40 degrees off centre beam.

Well, the fact that the Ferryside transmitter still has Mux A, and that whenever Arqiva write these proposals (eg for local TV), they usually take great effort to make sure that only a very small number of households could lose services they already have. It's a rule of thumb, rather than a written rule, hence me calling it a rule of thumb.

Thank you for your well informed and polite reply.

My response is that the Channel M licence is a licence that can be used in any mode and not even DTT. It was advertised with illustrative diagrams showing 16QAM & QPSK likely coverage with 1kW ERP with the antenna at half mast height or 500ft IIRC.
Is this not the case?

Blaming the planners is not really on because Ofcon are only advised by Arqiva and have the ability to make their own decisions. If Channel M really think that its transmitter power should be increased, it can make the appropriate submissions. However it should have done this before paying £10,000 for its licence. I don't think that it will be allowed because of the new local TV proposals.

Let's say that the DCMS local TV scheme goes ahead. You will have another Manchester local channel operating at QPSK 2/3 with Channel M on 16 QAM 3/4 both using 1kW ERP but with Channel M's antenna substantially lower than the other. The local TV will obviously outperform Channel M in coverage. If Channel M wants to increase ERP to 10kW then so will the local TV. It will still win.

BTW the planners are right to take extreme caution with power levels. We are only just beginning to find out just how compromised the DTT system is with interference especially under tropospheric lift conditions.

What Channel M have done wrong is they failed to have a prompt digital replacement for its analogue service. That the holding company was in economic difficulty is not relevant to the facts even though we may feel sympathy. Then they produced a good QPSK service, but once again lost all credibility by moving to 16QAM and presumably 64QAM in due course again losing a large number of households in coverage. I am afraid that Channel M have made their bed and must now lie in it. If Arqiva have made errors in advising Ofcon then that is another matter.

I am totally against monopolies, but the existence of Arqiva is designed to reduce costs and if it doesn't do so, then Ofcon is not regulating it properly. Personally I wouldn't allow Arqiva to operate any muxes itself but I suspect that re engineering the UK infrastructure for high power digital was so costly that some payback was made. Obviously there is a suspicion that Arqiva can manipulate the Manchester local TV market due to conflict of interest with planning. If Channel M has a case then it should go to the courts.

I understand that commercial considerations require as many channels as possible. But that is simply not possible without technical improvements that are probably not achievable. After all this is an exercise in "topping up the tank" with interleaved spectrum, not primary use of the spectrum. Channel M needs to realise that it cannot have unlimited spectrum and power and go back to QPSK. In any case all we will all be watching ipTV in 5 years time won't we?

BTW where's plane spotter?

I believe he got into a fight with Jonathan Ross.

Incorrect.

With regard to Arqiva's involvement in local TV, this can be controlled if Ofcon does its job properly. However as I stated in my response to FRANKIE RAY, QPSK for local TV is the only possibility until ipTV is up and running.

I disagree with your interpretation of vertical alignment. In practice aerials are not always pointed directly at the antenna, they are aligned to achieve the best response across all channels. Adding an antenna 1000ft below the others in the DTT bouquet will not help existing receiving households in the same way as reserve antennas do not always supply the signal strength that they are expected to.

I'm surprised you accept what your "bean counters" are doing. If they are running Channel M in 16 QAM the disaster will continue. IIRC the bean counters were in charge of OnDigital as well and they got their engineering wrong as well.

Otherwise I refer you to my earlier reply to FRANKIE RAY.

And gain more viewers in Southern Manchester like Macclesfield perhaps?

It was fine in my grandmother's house in Chelford near Macclesfield when it was QPSK. No idea about now, I haven't visited since the change.

Whatever you say, dear chap!

No, sorry you're still incorrect. I actually can't remember the last time I saw an aerial that wasn't anything other than 90 degrees to its mounting pole. Brushing off my scientific calculator, the difference in height between the two aerials is only 1.1 degrees at my house (roughly 10 miles away), go to Chelford (for example) and that reduces to 0.4 degrees. Even in the middle of Bolton the figure only increases to 4 degrees.

How would you even set an aerial to that sort of precision? Last time I put an aerial up, the mount only moved in approx. 15 degree increments.

In outlying areas, this lack of height may be a contributory factor, but for the bulk of Greater Manchester (where the vast majority of the households are), it isn't. The argument stills goes back to more power to compensate for building clutter.


The only accountant I deal with is my wife. So, sorry, wrong again. This is getting to be a bit of a habit for you.

If they want to run 16QAM and accept the pitfalls in doing so, what's the problem? It's not like they're a public service broadcaster.

Quite a few in north west Nottingham are - but then again they are in the bottom of a valley right next to a transmitter plonked on top of a hill

I can understand it in a situation like that, ISTR some properties in the immediate vicinity of Emley Moor (ie Jagger Lane) being like that too.

You're getting confused now. The effect of having antennas at different heights on a mast is not that the receiving aerial goes out of its capture angle (except close to the transmitter), it is an adverse reduction of signal strength at the receiving aerial that has been previously set up to balance the previously existing DTT broadcasts. Balancing is usually done by moving the existing aerial within an imaginary 1m cube to optimise reception between all six frequencies. Pointing directly at the transmitter is ideal but not always obtains the best reception. The reason is different propagation characteristics between the different frequencies with reflections occurring at different angles depending on frequency, especially in built up areas and is one reason why antenna sharing is used on the transmitter mast.

With Channel M using a different antenna at 50ft height, when its DTT neighbours are at 1000ft, is asking for trouble not only with the above but in particular with ground effects. This is at the limit of my knowledge but basically the closer the transmitting antenna to ground level, the more RF energy is absorbed by the ground. This can have different effects at the receiver because of different reflections along the signal path including those caused by ground terrain characteristics requiring a realignment to the receiving aerial. Remember we are not talking about good reception line of sight areas here. The problem is city centre high rise and office buildings plus urban areas south of Manchester City but still within Greater Manchester.

So to summarise, just using an antenna low down on the mast is sufficient to achieve substantially different coverage from main DTT reception possibly requiring aerial upgrades and realignment.

Whatever you believe, I think that Channel M need to raise their antenna as high as practically possible. In fact I'd love to see projections of their coverage at 50ft in 16QAM at present. It probably won't reach the other side of Manchester. No wonder they want a power increase. Good luck if they get it but I doubt that Ofcon will be hoodwinked.


But you're contradicting yourself


and how do you know that this is true? Could it not be down to inept management failing to understand the basic engineering? Are you not concerned about Channel M committing suicide like OnDigital through lack of viewers? I thought you were a Channel M supporter but it seems you are happy to let them go and defend everything they do. This is the management of the GMG subsidiary who tried to sell Channel M off and made almost all employees redundant. All they seem to have done is brought the Men & Movies suite of channels to a very small number of Mancunians. Is this local TV? No it's a futile attempt to become a mainstream TV broadcaster which will be seen for what it is and rejected. They will not make a silk purse out of a sow's ear.

I think the main (and possibly only) reason Arqiva uses antenna sharing is actually to save weight and space on the mast and also the cost to put it all up there. I'd say those factors alone make it worthwhile. Not to mention the fact they run and maintain all the TV transmitters and associated kit on each site.

I think we're going to have to agree to disagree here. While there would be some advantages to raising the aerial height, I don't think the issue is nearly as serious as you make out nor do I think they need to be raised that much further than they currently are. The main reason I can see is reducing the shadow caused by the hill.

I don't, I'm simply guessing. Why else would they spend over a year in one config, spend a couple of months in another, then go back to the old one? Sounds like an experiment that didn't work to me.

I think lack of new, interesting local content is what's going to drive viewers away from Channel M. I wouldn't be surprised if the the Movies4Men channels have significantly more viewers than Channel M does currently.

It's hard to understand what they're trying to achieve, and until DCMS puts forward a final proposal, I wouldn't be surprised if they knew what they're trying to achieve. I assume it's currently just to stick around until the licences are contested, throw their hat into the ring and see what happens. I seriously doubt if they were to be unsuccessful that they would carry on in competition with whoever did win. Of course Movies4Men isn't local TV, it's an attempt by a local TV company to use their surplus capacity to generate revenue to invest in local TV. Whether this is actually working in a financial sense, only they know.

From what I can see, it's a toss-up. Move to QPSK and possibly get loads of people watching a channel with seemingly no advertising or sponsors (therefore I assume making no money) or stick with 16QAM and make some money transmitting other people's services to a reduced audience until the time is right to relaunch and spend some money re-engineering things to optimise coverage.

.

.Radio horizon at 66m = 29miles 400m = 60 miles and at 450m = 63 miles with the RX antenna at 10m AGL(HAT)

Whaley Bridge 29 miles away is were the terrain starts to impede coverage. beyond that the Peak district and not much propagates further from Winter Hill .
The 300m tower at Winter hill is needed mainly for propagation to the North and the South .

As Channel M,s radiation pattern restrictions will not provide much coverage to the south and none to the North . So there is no benefit in going higher.

At 29 miles with no terrain ,vegetation or building clutter impediment to the signal at 700MHz a rooftop antenna with 10dB of gain and allowing 3dB for feeder loss will provide approx 50dBuV with 1kW ERP and with 100kW ERP 70dBuV into the receiver .

20dB margin is what planners would like to work with, above this multipath becomes a major issue .

City Centre and the immediate suburbs of Manchester is approx 16-20 miles and does need a higher level of signal to overcome the City Centre Building clutter .
In my opinion 10kW ERP if 16QAM is used, but any increase at all would be a huge improvement because of the adjacent channel at 20dB higher and the restrctive antenna radiation pattern..

Beam tilt can be used along with keeping the TX antenna low down the tower to reduce interference to others if higher power is allowed.
However the log antennas specified by the planners are totally unsuitable for this purpose unless a complicated multiple array is used..
It needs a four or eight bay panel array.

This has been known from the start by channel M but the transmission parameters and antennas and radiation were imposed by the planners and as I said before the restriction template not shown to them at the time that would have allowed for much better coverage due to a possible better radiation pattern.

Ray if you disagree with my conclusions I respect your opinion.
What is important is a candid ,honest and frank exchange of views .
PS detailed coverage analasis has been done.

That is another reason but not the only one.


Or that they wanted to test the QPSK coverage?


If you were Ofcon and Channel M applied for any of the three Winter Hill local TV licences, would you entertain them? The first thing you would do is look at their track record which is absolutely no attempt (well maybe 2%) at any digital local TV at all. Then you have their weird engineering problems and finally their questionable management. They haven't got a bat's chance in hell. I personally think that their best bet is testing new channels for national Freeview rollout, which may be what they are doing with Men & Movies. But there's no chance that they can compete against a local TV station using QPSK if Channel M retains its present antenna arrangement. What they need to do is to share the new antenna at 500ft.

Macclesfield is in Cheshire not even Greater Manchester! It would also be a requirement that signals do not go outside designated areas so height could be used to restrict distant reception.

Yes the adjacent channel at high power is another problem, but only at 16QAM which is why that mode shouldn't be used! QPSK would have more margin. The latest DTG spec for Freeview HD receiver qualification will require a severe overload test to cope with potential high power 4G interference in the soon to be sold off 800MHz band. That might help Channel M to run at >20dB margin.

Why not share the future local TV antenna which could be a side mount panel or logs according to Arqiva? They will be pumping out a similar beam towards Manchester for their local TV on UHF57.

Is there any public data on the analysis that has been done at 16QAM with the low antenna? Has it taken the ground effect into consideration? Or does Winter Hill slope down rapidly?

Do you know how the regulator is dealing with this presumed licence amendment request? I still feel that Channel M thinks that it has a right to something that it was never intended to have. Namely a large broadcaster out of a local TV station.

That area considers itself part of Gtr Manchester and was in the coverage area on the original proposal.

Which I assume didn't work out for whatever reason, hence the fact they changed back.

For a kick off, Ofcom/DCMS would take a neutral view of all the licencees, you'd have to admit you're pretty biased (as am I). But seriously, I'd say they were the best bet by a country mile. Their track record is pretty substantial and considering the station is effectively mothballed, they do seem to be generating some new content, albeit a fraction of what they used to. I'd have thought the only thing could stand in their way would any past regulatory or legal infractions, and to the best of my knowledge, there are none. If their licence application is appealing to whoever is awarding the licences, then I see no reason why they couldn't win, especially if they were to be prepared to invest their own money into the operation as well.

They're the only company with any experience of running local TV in Manchester, backed up by GMG's existing news gathering resources in the region. Given some of the volunteer led, community based outfits that have come forward to express an interest in the licences, a company the size of GMG should have as good a chance as anyone. They've also proved it's perfectly possible for a local station to successfully run its own multiplex, despite your personal misgivings about the modulation scheme they've chosen and the height of the aerials (the reasons for which neither you nor I are privy to).

The main newspaper publisher and one of the larger TV production houses in the area have also stated numerous times that they don't think local TV will work, so I'd be surprised if they were to have a sudden change of heart and express an interest. Which I'd have thought pretty much leaves only the part-time local 'enthusiasts' who'll give it a go for a couple of weeks, realise it's pretty hard work and give up.

Like I said, what would be the point in two local TV stations?

Given the licence is only interference restricted, they just have to prove that any changes they make won't affect other sites using channel 57. There's certainly no rigid prescribed TSA restrictions in the licence.

You're assuming they're even pushing for a power increase, where's your proof? All I can see currently is a licence holder working within the legal boundaries of their existing licence and finances to maximise their investment. You seem to be constantly looking for some sinister ulterior motive.

I don't understand this at all. Why not have two local channels? Gtr Manchester is quite large.

Anyway Channel M is not a local TV station any more. If it was it would be no contest. Like I said, it seems to want to be a major broadcaster but without the resources. I think Channel M will be a test bed for Freeview rather like London theatre productions are tested in rep.

Compare Channel M to a volunteer group perhaps with Salford back up who will be effectively given the airwaves FoC. Channel M will not be able to make any money out of the new local TV. They won't even apply IMHO. The volunteers would get it. So we'll have to see who turns out right on this one.

FRANKIE RAY seems to suggest that they are pushing for more power which is why I quoted his post in my reply and the question was directed to him.

I don't see a sensible business operation I'm afraid but that has already been said.

Is anyone aware of any public ofcom documents which detail the current channel M licence requirements?

Every other UK DTT mux is listed in: http://licensing.ofcom.org.uk/binari.../Version_6.pdf but I find no mention of channel 57 from Winter Hill.

I'm aware of the October 2008 document at http://stakeholders.ofcom.org.uk/bin...tice524/im.pdf but that seems to have been consistently wrong/ignored/outdated in terms of number of antenna, arrangement and height.