Film4 signal on Freeview's rubbish

Turkey Machine · 28-06-2009, 15:47

Because us in Lowestoft are out on the sticks of the nearest transmitter 40 miles away, we've always had a less-than-ideal signal. However it's been good for now, until a couple of weeks ago when Film4 started breaking up randomly. Every other channel (and I mean every other channel, I went through the entire list) is fine, no breakups whatsoever. So what could be the problem? No birds perching on the aerial, it's pointed in the ideal direction, could it be the box needs re-tuning?

nodrogd · 28-06-2009, 18:11

If the other Mux D channels are behaving themselves (4 music, TMF, Yesterday etc) then the problem is more than likely on the encoding side at Tacolneston or the incoming feed to it. Do any neigbours have the same problem on freeview ?

Turkey Machine · 28-06-2009, 19:06

Quote:

Originally Posted by nodrogd

If the other Mux D channels are behaving themselves (4 music, TMF, Yesterday etc) then the problem is more than likely on the encoding side at Tacolneston or the incoming feed to it. Do any neigbours have the same problem on freeview ?

No idea, everybody save us has a Sky dish up our street.

Kymmy · 28-06-2009, 19:09

A retune only takes a couple of minutes.... so suprised you;ve not yet tried it.

Freesat is made for situations like this where the freeview signal isn't ideal from a ground based transmitter..

**Chris** · 28-06-2009, 19:20

We've tended to have high pressure over the UK over the last couple of weeks, with higher humidity and lots of cloud about. It could be as simple as bad atmospheric conditions causing your problem. However do as Kymmy says and try a re-tune and see if that makes a difference.

nodrogd · 28-06-2009, 23:04

Just seems strange that one channel would be affected like this when it appears all the other channels carried on that Mux are not.

Turkey Machine · 02-07-2009, 23:11

I have now checked all other channels on that mux, all bar Virgin 1 are breaking up. Could something have been changed at the transmitter?

Other thing is the "basket" on the back of the aerial's a bit cock-eyed on the top-side of the aerial. Could that affect it? Been like it for a year, Film4's only been breaking up since June.

---------- Post added at 23:11 ---------- Previous post was at 22:02 ----------

And I've just checked the list on Wikipedia which is far more accurate, and all channels on the "D" mux are breaking up. (C64 at Tacolneston)

So what could be done about it? My Dad's prohibited me from re-scanning the box cos in high pressure we lose a lot of channels in a re-scan.

popper · 03-07-2009, 01:35

if the same Mux is bad for all of them as you say, then the only option short of going up there and adding some form of higher gain arial or extensions, is a signal booster on the TV end of the coax, to compensate for the long feed lead signal loss.

that so called basket is your parabolic reflector on the "yagi" helping to concentrate the incoming radio waves on to the dipole feed, if its not evenly spaced to the other side, it MAY (or not) be concentrating the radio wave in slightly off center hence giving a slightly lower db gain that its rated for, the higher the gain on the arial the better and stanger the signal down your coax.

exactly the same idea as the wireless router DIY arials/reflectors booster text iv posted elsewere.....but tuned for the DVB freqs OC

basicly the more elements a Yagi arial has the higher its gain and the stronger it can pick up the signal from 40 miles away...

this ones got 15 elements plus the dipole at the end then the reflectors at the back concentrating the incoming signal on to the dipole with the black arial cover connected to it...

something i didnt realise until i looked too

each DVB-T element group is a different size

---------- Post added at 01:35 ---------- Previous post was at 01:31 ----------

if you wernt so far away you might have got away with a higher gain arial mounted in the loft were you could have easily got to it and adjusted it for best picture on the weakest analogue picture.

you do it that way so as to maximise for best digital reception without a meter to help you point it optimally.

you can still try that OC but at 40 miles its going to be more than borderline not being line of sight outside....

the booster seems like your probable best option, and it neednt be a great gain to bring the mux into signal strength, its usually eather in or out with digital reception and it sounds like its just outside that clear digital reception line right now....

Turkey Machine · 03-07-2009, 14:10

I should add there is a booster in there, down by the wall point. But if it's all on one Mux the channels are going patchy, I guess a box re-scan in low-pressure is a better idea.

altis · 03-07-2009, 14:49

IIRC, the East coast down near Lowestoft suffers from co-channel interference from TV transmitters over the water on the continent. The problem also works the other way so there is a limit to how much they can turn up the transmitters here.

I'm inclined to go with Chris's idea of weather causing the problem.

Although Freesat must be your obvious solution a better aerial may well help. You'll need one with very small side-lobes and this may not be the one with the highest gain. I suggest you consult a local aerial man - he'll know what's best (or he should do!)

Turkey Machine · 03-07-2009, 15:50

Yes, there is ghosting from transmitters across the water. I think a repeater in Lowestoft covering the town would be a better idea, but at the moment, yes, Freesat is the best option in this town. Hence, the amount of dishes on houses.

nodrogd · 03-07-2009, 19:40

There are channels reserved for a DTV relay in Lowstoft post switchover, but it will only carry the 3 PSB Mux.

Co-channel interference could be the problem, or possibly a deterioration in the co-ax or aerial. Coastal locations are notoriously corrosive and when installations start to fail the highest frequencies go first. Mux D on Ch64 would be the most likley to go in this situation.

popper · 04-07-2009, 00:34

ive never looked, but do they do higher focused directional DVB arials than a yagi (but not as focused as a dish) ?

the thinking being if you can use a cheap commercial higher focused arial and also increase its db gain at the same time, that will go a long way to remove the Co-channel interference providing that second EU transmitters not within the same degree angle as the new focused receaver....

hmm, putting my DIY/cheap hat on, perhaps you could make a generic mesh cantana enclosure of the right dimensions to make a generic yagi become far better at excluding this Co-channel EU interference and narrowing the transmitter beam angle pickup at the same time ?

wire mesh to allow the wind to flow through it if its outside OC, and you need to work out the right diameter and optimal focal point to place the dipole part inside.

for fun, you could go the easy route and hack the dipole part of a DVB yagi onto the focal point end of an old parabolic sat dish OC but your going to get freesat if you are going to do that anyway

but then the man in a van with a ladder, will be most peoples first choice