Testing a TV aerial.

[Andrew Br]

One of my digi boxes has stopped working recently while the other one still gives a decentish picture.
The one that still works is a very cheap (£30) thing, the other a relatively expensive DVD hard drive recorder/DVD player/digi box.
Both of them are piggy-backed into each other from the same roof-top aerial connector and both feed the same TV.

I've done the following:-
1) Turned them all off and back on again 
2) Taken one out of the circuit and taken the aerial lead directly to the other
3) Used a different lead from the aerial
4) Retuned them
5) Borrowed another digi box and tried that (it didn't work)

The result is the same; the cheapy box still works, the other (still) doesn't.

Is there an easy way that I can test if there is a signal coming down from the aerial ?
I'd rather do that before I GSI.

Any thoughts why one box would work while the other doesn't ?

(I've got two boxes because I can't record one channel and watch another on the expensive kit.)

[Biggsy]

Some boxes apparently don't work with certain new frequencies that some channels have moved to.  Or the the signal may have deteriorated recently, but the cheapo box happens to be sensitive enough to deal with it while the other isn't.

http://www.ebay.co.uk/sch/i.html?_nkw=tv+signal+meter+-satellite&_sacat=0&_odkw=tv+signal+meter&_sop=15&_osacat=0&_from=R40

[frankly frankie]

I have similar.  2 digi boxes (recorders), one cheap, one not, then the digi TV.  The aerial goes >>box1>>box2>>TV.  The TV picture is spot on (and meters as 'full' strength) but both the boxes fail on the same two mainstream channels that I sometimes want to record, but are spot on on most others.  I have distant line of sight to the transmitter.

Each box I assume amplifies the signal before passing it on, so that could explain why the TV at the end of the chain gets the best reception.  Or very likely it's just a better receiver.
Have you tried (6) passing the signal through box2 to box1, as opposed to through box1 to box2?

BTW the solution to my problem is simple enough - both affected channels have '+1 hour' timeshifted replicas, and they receive and record OK ...

[Valiant]

Buy one of those testers that Biggsy suggested, bear in mind that you might have to buy say a distribution amp and maybe dial the signal down. Too much signal is also a bad thing. If the cheapo box is working fine, it's likely the decent on will have better tuners...

[aidan.f]

The  e-bay  link is to cheap satellite meters which look at broad-band Sat IF. They  are  connected to  LNB  outputs for dish  peaking.
(when on a  rooftop) Even for that  purpose they  have limitations.

The OP more than implies that he has a  problem with DTTV.
The receivers should have a signal quality menu which will give an indication of carrier to noise on the  multiplex that the set top box is  tuned to.
What  is it? good, bad, indifferent?

[Biggsy]

The  e-bay  link is to cheap satellite meters which look at broad-band Sat IF.

No it's not.  It includes a minus sign before "satellite", and the results are for DvB or Freeview meters.

Slow down Sleepy and have a longer look. 

[Kim]

Still really a job for a spectrum analyser, thobut.  Preferably one that speaks DVB-T.

Those meters will presumably help you align the aerial on a signal source, in the same manner as a satellite finder, but aren't going to tell you about what the signal actually is.  Which isn't going to help if there's something interferency going on.

That said, if all things being equal, one box works and another doesn't the issue lies at least partially with the box.

[Biggsy]

Choco just wanted something to "test if there is a signal coming down from the aerial" - but I suppose it's not worth buying anything just for that.

[Kim]

Choco just wanted something to "test if there is a signal coming down from the aerial" - but I suppose it's not worth buying anything just for that.

Not when you've got a working box, no. 

[aidan.f]

No it's not.  It includes a minus sign before "satellite", and the results are for DvB or Freeview meters.
Slow down Sleepy and have a longer look. 

Excuse me - it's  Mille  Alba - on the trike wot gone done it
Still don't  know what Chocolate bike's Signal menu is showing  on the  working  box. Probably  worth waiting to see what  his  reply  is.

[Andrew Br]

OK, update.

I got one of the signal testers off Ebay and it only lights one of the (four) LEDs so the signal strength is very low.
The cheap box (A) still works, the expensive one (B) doesn'f.

As a further experiment I wired the boxes A->B->TV, B->A->TV, A->TV, B->TV. The TV is analogue so I don't really need to include it in the aerial circuit; the boxes feed the TV via SCART cables.
I still couldn't get B to work so I'll have to see about getting the landlord to sort out the aerial. No way am I going up there..........

Thanks for all the input folks.
I you have any further ideas, I'll be pleased to here them 

[rafletcher]

You could try a plug-in powered booster if the landlord is likley to cavil/delay.

http://www.argos.co.uk/static/Product/partNumber/5346161.htm?CMPID=GS001&_$ja=tsid:11527%7Ccc:%7Cprd:5346161%7Ccat:home+entertainment+and+sat+nav+%2F+televisions+and+set+top+boxes+%2F+television+aerials+and+boosters+%2F

I suspect that he may not consider the provision of a TV signal as a fundamental human right!

Actually I have a redundant one (a bit chunkier than the one I linked to) that I could send you if you'd like?
 

[frankly frankie]

That said, if all things being equal, one box works and another doesn't the issue lies at least partially with the box.

If the boxes are chained, all things won't be equal though.  The signal level strength will vary (maybe down, maybe up) along the chain.  The S/N won't change much (nor will a booster improve it) but that's less likely to be the issue with digital.  The various boxes' own signal strength meters won't be comparable with each other.  Try that ebay signal tester at each point along the chain - just for interest.