Quizzes & Puzzles0 min ago
Freeview - BBC channels gone AWOL
2 Answers
The BBC channels on Freeview have disappeared. We can get them without a problem on a different TV in a bedroom about 8ft away, but not on the main set in the living room. I thought retuning would solve the problem, but it doesn't. It's been about 3 or4 days now.
Any ideas why this may have happened?
Thanks!
Any ideas why this may have happened?
Thanks!
Answers
1 to 2 of 2
Best Answer
No best answer has yet been selected by squidgster. Once a best answer has been selected, it will be shown here.
For more on marking an answer as the "Best Answer", please visit our FAQ.
Point 1:
Even though the signal strength at the transmitter normally remains constant, the strength of the signal received by your aerial can vary quite a lot. It's affected by the length of daylight (which determines the height of the reflective layer of the earth's ionosphere), the weather (which can affect the transmission path), the 11-year sunspot cycle and individual solar flares on the sun's surface.
Point 2:
In a perfect world the lengths of the elements on a TV aerial should be exactly matched to the incoming frequency. Since every channel is on a different frequency you theoretically need a different aerial for every channel you watch. Clearly that's not practical, so we use aerials which are a 'rough match' to all of the incoming frequencies. Consequently each aerial will be better at receiving some channels than others.
Point 3:
Different models of TV sets have different 'sensitivities'. (i.e. their ability to 'pull in' weak signals).
Putting it all together:
Your aerial is weakest at receiving the BBC group of channels. When the received signal strength drops (due to the conditions mentioned above) it's 'borderline' as to whether a particular TV set can resolve them. Your bedroom TV has got good sensitivity, and can cope with the borderline signal. Your other TV has got poorer sensitivity and can't.
Solution:
Since the signal is strong enough most of the time, a simple signal booster might well do the trick. Otherwise you need to replace the aerial (and, just as importantly, its associated cabling).
Chris
Even though the signal strength at the transmitter normally remains constant, the strength of the signal received by your aerial can vary quite a lot. It's affected by the length of daylight (which determines the height of the reflective layer of the earth's ionosphere), the weather (which can affect the transmission path), the 11-year sunspot cycle and individual solar flares on the sun's surface.
Point 2:
In a perfect world the lengths of the elements on a TV aerial should be exactly matched to the incoming frequency. Since every channel is on a different frequency you theoretically need a different aerial for every channel you watch. Clearly that's not practical, so we use aerials which are a 'rough match' to all of the incoming frequencies. Consequently each aerial will be better at receiving some channels than others.
Point 3:
Different models of TV sets have different 'sensitivities'. (i.e. their ability to 'pull in' weak signals).
Putting it all together:
Your aerial is weakest at receiving the BBC group of channels. When the received signal strength drops (due to the conditions mentioned above) it's 'borderline' as to whether a particular TV set can resolve them. Your bedroom TV has got good sensitivity, and can cope with the borderline signal. Your other TV has got poorer sensitivity and can't.
Solution:
Since the signal is strong enough most of the time, a simple signal booster might well do the trick. Otherwise you need to replace the aerial (and, just as importantly, its associated cabling).
Chris
1 to 2 of 2
Related Questions
Sorry, we can't find any related questions. Try using the search bar at the top of the page to search for some keywords, or choose a topic and submit your own question.