Bad reception on freeview

[Sharpie]

I have Sky but use a freeview box in the kitchen. Lately it has suffered from poor reception, especially so when it is cold and not necessarily related to pressure systems. The poor reception ranges from some pixellation to almost complete breakup. Now it will only tune in to BBC stations, but midday today there was excellent reception.
There is an amplifier in the loft taking it's signal from a roof ariel which has always worked well in the past. I've checked it out and it all appears to be in good working order.

I'm guessing that the problem is in the broadcast infrastructure, but I can't find any info on it by searching t'internet.
I am in south Bucks, any ideas?

[pb6797]

Have you retuned recently? There was a spectrum shift in, erm, October I think.

I believe that the whitespace which formerly protected Freeview is being used by the new 4G services so that may also be causing you an issue :

http://www.theregister.co.uk/2012/10/18/ofcom_mitco/

[Boxkite]

I have had problems in the last 2 months, mostly with weak BBC (1-4) signals. Same problem on two different boxes (that seem to have similar software). A 'borrowed' box from Argos cured it but went back as the menu system was awful.

[Paul_Sengupta]

I believe that the whitespace which formerly protected Freeview is being used by the new 4G services so that may also be causing you an issue

Unlikely to be that as the 800MHz 4G licences haven't even gone out to tender yet, let alone any infrastructure be installed.

[pb6797]

No testing? Any other ideas on the interference then?

Would suggest some ferrite rings around the co-axial cable, it's always possible there is something unsuppressed somewhere.

[nbayliff]

I have Sky but use a freeview box in the kitchen. Lately it has suffered from poor reception, especially so when it is cold and not necessarily related to pressure systems. The poor reception ranges from some pixellation to almost complete breakup. Now it will only tune in to BBC stations, but midday today there was excellent reception.
There is an amplifier in the loft taking it's signal from a roof ariel which has always worked well in the past. I've checked it out and it all appears to be in good working order.

I'm guessing that the problem is in the broadcast infrastructure, but I can't find any info on it by searching t'internet.
I am in south Bucks, any ideas?

Very heavy frosts and then lots of rain can really make a mess of older coax cabling. Are you sure you have no cable or masthead degradation?

[Paul_Sengupta]

No testing?

Only in labs at the moment.

I'd go with the wind moving the aerial or water or other degradation of the coax.

[Tarnish]

Is there a Kenwood (other makes are available) food processor/mixer in the kitchen?

Our new Kenwood mashes the digital signal on most channels yet the old one (20+ years old) has no interference at all.

Picture settles after Kenwoods use, but is a bit trippy until you switch TV to standby and back on again.

Steve

[Keef]

If you haven't retuned in the past couple of months, do that first. Several multiplexes changed frequency recently. Most have increased power, so your reception should be getting better, not worse.

Can you get to the preamplifier to see if the light on that is showing? They usually have a "power on" LED.

Have a look at the aerial through a pair of binoculars. Is it pointing in the same direction as the others around you?
Does it look sound? Is the cable clipped down, or is it flapping about in the wind? (Metal fatigue affects coaxial cable, too).

Listen on a radio receiver, tuned off any station on the long or medium waveband. If you hear loud electrical noise, you may have a local interference source.

Do your neighbours report the same problem?

[Paul_Sengupta]

My microwave oven blots out the satellite telly if I point it at the dish when it's turned on. The dish is down the back of the garden.

I don't stand in front of it when it's on any more.

[Sharpie]

Thanks for the comments.
The amp is alive and well and functioning. The mast looks fine, I have had a good look with binoculars.
But the reception is often OK so I am surmising that it's not a structural problem.
I have retuned it - a number of times.
Using electrical-electronic equipment makes no difference.
Tried the portable radio - no relevant interference.
Haven't talked to a neighbour who might have freeview, so I guess I need to find one.

[Keef]

Reception sometimes OK, sometimes not...

Are there any trees in the path the aerial looks along to the transmitter? Wet trees absorb RF energy quite well.

Otherwise, does rain affect the signal? It could be rain getting into somewhere it shouldn't, such as the coax feed from the aerial.

The aerial on this house was mounted upside-down when we moved in - the balun box pointing upwards, so it filled with water. It was badly corroded so I replaced it with a new one, pointing in the right direction. TV reception improved no end.

[Hotelfox]

As Keef said, we had the same problem 3 years ago. Very bad picture when it rained. Antenna specialist came out and said that the signal was affected by the wet trees, which zapped the RF energy.

[Sharpie]

There are trees around but they've always been there and the reception has been fine for the past dozen years.

Might be water in the works, but I'm trying to avoid ariel guy if it may be something simple. Rain alone doesn't appear to have an adverse effect on the signal, but cold weather does.
OTOH, if it were something simple I would have come across it by now. I guess I wondered if anyone had a good knowledge of the freeview broadcast system, and specifically in Bucks. Why, for instance if it were system trouble would I get a good reception sometimes but only get BBC channels?

Thanks anyway for your thoughts!

[Keef]

There are trees around but they've always been there and the reception has been fine for the past dozen years.

Have they grown a bit taller, perhaps?

Might be water in the works, but I'm trying to avoid ariel guy if it may be something simple. Rain alone doesn't appear to have an adverse effect on the signal, but cold weather does.

Hmmm. Unusual, that. Maybe there's a break in the aerial cable and the cold causes the wires to contract and open the break.

I guess I wondered if anyone had a good knowledge of the freeview broadcast system, and specifically in Bucks. Why, for instance if it were system trouble would I get a good reception sometimes but only get BBC channels?

Not specifically in Bucks, but the principles are the same everywhere. Digital multiplexes are transmitted on various channels - different sets of channels for each area to avoid mutual interference. That's why the channels were retuned several times recently: when the analogue signal was turned off, it freed up a load of channels so the transmitter power could be increased and the multiplexes spaced out better. It took several goes to move the muxes from their old to their new channels.

If you only get BBC channels now, and used to get them all, it sounds as if the other multiplexes aren't tuned in. Usually, the signal for all the muxes comes from the same pole, so if you get one you should get them all. Sometimes one may be transmitted with more power than the others. Do you know which transmitter site you are accessing, so that we can check that? Alternatively, where are you and which direction is your aerial pointing? Give us your Lat/Long and I'll have a look.

That will also indicate how good a signal you should be getting.

I suspect, however, that unless it's tuning then the aerial will need looking at.