What am I doing wrong or why won't this work?

Technology
#1

I am trying to get French terrestrial television. I have put up an aerial, very similar to my neighbour’s and pointed it in the same direction.
I am using good quality, new coax. lead, good connections.
With our French-bought TNT labelled television the best I can get is 5 channels listed (F2, F3 Aquitaine, F4 and franceinfo. Only on F3 Aquitaine do I get anything - and that is perfect sound + subtitles. No picture whatever.
With another set (British , maybe 10yrs old, don’t know) I get sound only on F3 Aquitaine.

I spoke to a TV man who said straightaway ‘TV tuner problem’. At that time I hadn’t tried the second television. With the British TV when tuning I got the same 5 french channels and all the information about the program title etc along the bottom, but no picture.

I have moved the aerial direction in a few steps either way and am pretty sure it is pointing as good as possible. It is correct way up, compared to neighbours.

What might be wrong? Two TVs with duff tuners? An amplifier needed? Better aerial?

Incidentally, both TVs work perfectly on Satellite via Humax and scart leads.

#2

Have you got horizontal vs vertical polarity correct?

#3

My aerial is not identical to next door’s. The dipoles are horizontal on mine (a single line of them). My neighbour’s aerial is one which has two lines of dipoles diverging in a Vee away from the reflectors. The dipoles are horizontal. Mine just has a single line of dipoles running away from the reflectors.

#4

Hmmm, those ones with two sets of directors are supposed to be high gain (though I think opinion varies as to how effective they are) - could it just be that you are in a low signal area?

The other thing to check is that the coax from the aerial is in good shape and the inner conductor is not shorted to the screen - is it new?

EDIT - Ah, I see you said new coax, I’d still double check that the inner conductor is not shorted to the screen.

If you are on decent enough terms with your neighbour perhaps it is worth asking whether they have any form of booster amplifier in their set up, they might also be willing to let you test the TV on their aerial.

Of course it could be that they don’t watch much TV and just enjoy listening to F3 :slight_smile: :rofl: :slight_smile:

#5

Paul, are you saying F3 is a sound-only channel?

I had a wander (there are 5 or 6 houses within 400m or so) and they are all horiz. polarised. Some point towards the bergerac Tx (which is nearer Sarlat!) and some point towards the south (someone local once told me that Tx is Toulouse, although I find that a bit difficult to believe).

#6

No, I was being not serious for a second :slight_smile:

How far are you from the transmitter(s) - do you know?

There’s an excellent site in the UK for working it all out including signal strengths and compass bearing to transmitters - wolfbane.net but I don’t recall if I ever found a French equivalent. I’ll have a look this evening.

I’d still ask a neighbour if they needed a booster amplifier fitting - you wouldn’t see that from outside someone’s house.

#7

About 50km and it is a 40kW Tx. I did read that over 40km can be a problem, but next door does get a good signal. I do know now that they have a signal amplifier fitted.

But I still hear what the TV man said - it’s not the aerial.

The site I have always used is satcure dot co dot uk , which I have always found to be excellent. It’s a doddle to sort out satellite pointing and troubleshooting and I’ve just seen it does Freeview , which I believe is the UK version of the French TNT service. So I’ll have a look on there.

#8

50km is going to need an amplifier I suspect and the info from your neighbour seems to confirm that, keep the cable run from the aerial itself to the amplifier as short as possible when you install one.

I found https://www.matnt.tdf.fr/ which looks like it will give you some idea of signal strengths and where the transmitters are located.

#9

Thanks Paul, very interesting and useful.
I’ll order an amp. When searching online what phrase should I use?

#10

Amplifcateur antenne TV faible bruit is probably a good starting point. Triax have some decent models.

#11

Very interesting to check what you should be able to receive through conventional aerial

1 Like
#12

Now that I have time to look properly amplificateur (de tête) de mât might be a better term.

E.g
https://www.triax.fr/produits/terrestre/amplificateurs/amplificateur-de-mat

Labgear is another decent brand

Even though these are described as mast head amps, and can typically be mounted outside on the mast they can also be placed in the loft. Usually the decent ones have F connectors, not coax. Power (typically 12V DC) is fed via one of the outputs (1-6 or so outputs is common).

Opt for a “low noise” (faible bruit) model, quoted in dB - < 1.5dB is excellent, < 2.5dB is good and > 2.5dB is OK through to “meh”.

Ideally go for the smallest gain that gives a stable picture, 25dB gain is typical (they go higher but the higher the gain, the higher the noise).

#13

It’s strange you say you have no picture. I can’t see why you wouldn’t get at least a poor picture. I can’t imagine an amplifier making the difference personally. I assume the aerial is mounted as high as the neighbours and not in a loft. Does your aerial have a lot of elements? They could make it more directional.
You should have something in the tv tuning functions to indicate received signal strength and quality.
You have retuned the tv to pick up the correct channels? Different areas use different multiplexes. Maybe I’m just used to being nearer powerful transmitters here in little old England. Is the tv aerial going directly into the tv? Do you have a meter to check for any short between the inner and outer on the coax from the aerial?

#14

The nice thing about the matnt site is that it gives the compass bearing so it should be possible to aim the aerial pretty well with a compass - don’t forget the angle of declination though most aerials, even highly directional ones usually have a “capture angle” of a good few degrees.

There are other reasons why reception might be poor even with a perfectly aimed aerial, such as a large hill between you and the transmitter - the wolfbane site takes all that into account which is why it is so good, but sadly UK only.

Another considerations is the “group” of the aerial - now I don’t know if this applies to France but, basically, it’s hard to make a Yagi (the most common type of TV aerial) which covers the whole of the UHF band so UK transmitters tend to keep all the stations quite close together and aerials are made in different “groups” which cover part of the UHF band. That way you get better aerial performance - the groups are as follows

image

The matnt site, unfortunately, does not give the actual multiplex frequencies though once you know the transmitter it should be possible to check - eg Vannes would correspond to a Group K (Ch 22-48) aerial.

#15

‘perfect sound + subtitles. No picture whatever’. - Very suspicious’ I would expect to get some sort of picture with an indoor aerial. Something wrong with the set up I reckon

#16

A well placed amplifier can make a considerable difference, that said a poor amplifier in the wrong position will tend to make things worse.

Two things matter, signal amplitude and noise. Amplifiers make the former better and the latter worse.

As the signal travels down from the aerial to the TV via the coax it will reduce in strength - all coax does this, good quality less, cheap stuff more (so the first port of call is good quality coax).

If the coax reduces the strength enough, especially if it was weak to begin with, what arrives at the TV input might not be much stronger than the noise inherent in the TV’s input amplifier. If you put a “booster” here, no, it probably won’t make things much better, unless it has a lower noise figure than the TV’s own amplifier (which, TBH, is not that common these days).

If, however, you put the amplifier at the other end of the system - before it has lost much amplitude down metres of coax it is possible to boost it enough to overcome the loss in the cabling and arrive at the TV in much better shape.

Digital is funny sometimes, there is a phenomenon known as the “digital cliff edge” - basically it either works or it doesn’t and the margin between the two is hair thin. I agree it’s odd but sound and subtitles are low bandwidth components of the signal and might just about get enough packets through to do “something” when the video fails to get enough data to make a complete picture (there’s lots of error detection and correction involved in digital telly but you need much more data intact to get a picture than you do to get sound).

The first thing I’d do, if the neighbour is willing, is take my TV round and make sure it works (and is tuned correctly). The second thing I’d do - knowing that Roger is probably in a poor reception area - is fit a good performance mast head amp, as close to the aerial as possible, and see what difference it makes.

#17

We live in a poor reception area for TNT where neighbours homes have aerials pointing in various directions in order to obtain a signal. The signal was lousy (unwatchable) until we had the aerial changed for one that was at least twice the physical size of the old one, and had the pole replaced so that the new one was considerably higher up in the air. Even with the improved aerial it still took some very fine adjustment to achieve what is now a very good picture quality.

#18

About face. Thanks everyone who has helped here, but I’ve decided to cut my losses and drop my attempts to get a terrestrial TV picture. I’ll just cast from my smartphone into my smart TV for when we want to watch French TV. It works fine and watching French TV will only be for when important announcements are going to be made / interesting sports programmes.

#19

Have you considered a satellite dish for Fr tv

#20

Yes I have.