Question about TV aerials (Bill Wright?)

[nothanks]

As I said earlier: I've replaced all the cable with WF100

[williamwright]

Sensitivity is not the same as gain.

Or increasing the level at a point where the s/n ratio is better, ie at the masthead.

Most masthead amps sold have too much gain.

Bill

[Martin Brown]

It helped noise on old analogue sets but much less so on digital - especially if the mast head amplifier is overloaded by just one strong channel in band and is generating intermodulation distortion as a result.

+1

Even then you need to be in a very bad signal area not to be able to get away with a passive splitter. Modern TV tuners are very sensitive now.

[williamwright]

It will improve it very nearly as much as the cable loss figure, which can be considerable. 4dB is a massive amount of difference for digital TV.

Bill

[williamwright]

You have a fundamental misunderstanding.

Reading what you say above, why do you believe that an amplifier can correct signal loss caused by sharing the signal between several outlets but it can't correct signal loss caused by cable length?

Bill

[williamwright]

For me it's the travel programmes with the scenery, amongst other things.

Bill

[williamwright]

What a set of snobs you are! There will be people in this group who live in council houses. You must be irritating them greatly.

Bill

[Peter Able]

Won't a group A aerial - particularly a big one - cripple the COM7 multiplex?

We (31 miles from Crystal Palace) were group A until that multiplex - just like Ridge Hill - was shifted to C55. It took a LOT of fiddling with my loft group A Yagi to get COM7 to decode reliably.

PA

[Andrew]

The new Humax Aura is said to be less sensitive than expected.

It seems to have been released with some unacceptable bugs and unfinished code. If the recent update has improved it I might get one. My HD-FOX-T2 has decided not to play ball with the iPlayer so it needs to be replaced.

[Andrew]

I'm quite surprised you can get C55 on a group A aerial at that distance.

[Peter Able]

Both C48 and C55 required working on.

It took a bit of fiddling in all three dimensions - and a professional Spectrum Analyser (chuck-out from work) - to get it to work reliably, but it has worked ever since.

It was fortunate that I could to some degree sacrifice the signals from the 20-something channels and still get 100% decode from them all.

PA

[Fredxx]

Does it have 'Dave'?

[Steve Walker]

Yes.

[Robert]

or All4 (4on Demand) which is more annoying.

[Robert]

Check the centre conductor hasnt snapped inside a connector, caught me out with a low signal issue !

[Martin Brown]

I'm with TNP on this one. Modern sets have such sensitive receivers that the problem is more with their ability to pick up remote transmitters in a sidelobe instead of the wanted stations in the direct beam.

Masthead amplifiers have largely had their day and for a digital signal can even sometimes make things worse by partially scrambling it. There might be some merit in a low gain one if you have horribly lossy cable. (but replacing the bad old cable would probably be cheaper and better)

My brother in laws TV airspaced coax is full of water this time of year!

[Andy Bennet]

Old Essex dialect for "put up with"

[Roger Hayter]

A Roku device will provide that for no subscription cost if you have a decent internet connection.

[Andrew]

According to the table for a group A Yagi, you should not be able to get anything at all in the 48+ range though ?. And your aerial is loft-mounted too ?. Strange.

[williamwright]

No, because with digital you don't see a snowy picture, you see nowt at all.

Because the difference in signal/noise ratio between good DTT and highly unreliable DTT is so small, a masthead amp can make a massive difference.

The chances of having one mux so strong as to overload a modern amp whilst the others need a masthead amp is so small that I don't think I've ever encountered it. Modern amps have a lot of headroom, not that it's needed for that scenario. It's always important to use a masthead with enough gain, but not too much. In-band muxes aren't the problem; it's things like mobile phone base stations.

Not a 'very bad' signal area. A 'mediocre' signal area. Emley Moor, and a village near Retford. Emley is the best tx because of hills in the way of Belmont. Everyone uses Emley without many problems. There are no big aerials or other signs of weak reception. Levels are dBmV (average across Gp B muxes) Output of a log periodic on the chimney -8 cables loss 3dB so -11 wallplate and flylead loss 2dB so -13. That's OK because it's still 7db above threshold. But cut the downlead in the loft and add a splitter to feed a bedroom and the living room telly is down to -17. That's only just above threshold. Reception will be unreliable.

Bill