freeview.

[villa_fan007]

recently our freeview box is freezing for a split second whle watching certain channels ..why is this and is it happening to anyone else.?

[Buenchico]

This is a classic symptom of insufficient signal strength (or of an interfering signal making it difficult for your receiver to resolve the primary signal).

If you live near an airport (or anywhere else where signal paths could be affected by intermittent 'bounced signals' ), you might be suffering problems associated with passing planes (or other types of vehicles). However, it's far more likely that your aerial simply isn't up to the job. Television signal strengths don't remain constant. They're affected by weather conditions, the heights of ionospheric layers (which vary with the seasons) and the sunspot cycle on the sun's surface. (Either way, you need to consider an aerial upgrade).

When Freeview was introduced, it was estimated that approximately one in three households would need to upgrade their aerial systems. ('System' means the aerial and the cable). In practice, it seems that fewer people need to change their aerials but it's certainly not unusual.

First, try a cheap signal booster (from Tesco Extra, Asda or Maplin Electronics). If that doesn't work, get hold of one of these
http://info.maplin.co.uk/module.aspx?moduleno= 22523
and have it professionally installed, together with new cabling.

Chris

[villa_fan007]

thanks chris thought as much ...but the problem only occurs on certan channels...the ariel we have is quite new (we have lived here for 5 years, and i think it was new then).
also the old box we had was ok. its just the new DTR box which is doing it.
also why cant we get ITV ITV2 Channel 4 on channel's 3 4 6. but can on channels 801 802 803.

[webdude]

You said *recently* in your quesiton, and if like me you live in a fringe area, then it is almost certainly down to the bad weather conditions we have been having over the last week or so. I receive the Sutton Coldfield transmitter via a high gain wideband antenna, and for the past week or so my BBC1 and 2 signals have been breaking up badly.

We are in an area where officially we cannot receive freeview, but with a good antenna and and high gain amp, we can normally get most stations.

Check this site http://www.radioandtelly.co.uk/freeview.html for information about your area, you may be able to tune to another transmitter and get a better picture.

[Buenchico]

Villa_fan:
You're post simply confirms my suspicions that the problem relates to insufficient signal strength.

In a perfect world, the lengths of the elements on a TV aerial should be exactly matched to the frequency of the incoming signal. However, that would mean that you'd need a different aerial for every channel. Clearly that's impractical, so all that any aerial can do is to offer a 'compromise solution', where the elements are roughly the right length for all channels, rather than being exactly matched to a specific channel. Inevitably, the quality of the 'match' between the length of the elements and the incoming frequency will be better on some channels than on others. (Additionally, I've seen a post here on AB which stated that the ITV channels use a slightly different form of encryption, which requires a stronger signal for faultless decryption. I know nothing about this but it seems to be consistent with the fact that it's nearly always the ITV channels that people have problems receiving). That's why only some channels are affected by the problem you report.

Different TVs and Freeview boxes have different 'sensitivities' to incoming signals. (The 'selectivity', which is the receiver's ability to ignore interference from signals on neighbouring frequencies, also varies). Some are better at 'pulling in' weak signals than others. Your new receiver simply can't cope as well with the weak signal from your aerial as the old one did.

Additionally, as I previously indicated, the received strength of TV signals is not constant. For the reasons I gave (including the weather factors mentioned by Webdude), there are seasonal differences to the signals received by your aerial.

I remain confident that the problem will be solved if you improve the strength of the incoming signal. Since you've obviously got a signal which is nearly (but not quite) strong enough for reliable reception, a

[Buenchico]

. . .cheap aerial booster may well do the trick.

Chris

(I hate it when AB cuts off the end of an answer without warning!)

[villa_fan007]

good stuff many thanks all
very helpful