Indoor Signal - Sucking My Will To Live

[leevis]

Hi All
I recently have an on-hold roof aerial and splitter issue which i don't think i will ever be able to resolve but will get on it once it stops raining here.

Anyway, i have another issue which is similar

I am trying to get a tv signal into my kitchen/dining room which is proving to be almost impossible.

I have tried all sorts of internal booster aerials etc but ALL make the picture break up at some point. Now, i must have spent more on internal aerials that the Tv itself if i am honest.

I just bought a mini log periodic and using my tv signal strength meter i can get no signal indoors and only one green light outdoors (i was hoping for MUCH more). Kitchen is on ground floor so i appreciate might be hard but i am only 16 miles from Crystal Palace, surely I should get something pretty good indoors?

Am i dreaming?

 

[Lucid]

Sorry to be direct.... but stop farting around with DIY solutions. It's clear they aren't working for you. You're wasting time and money on sticking plaster fixes.

Just ring an aerial installer. Get one decent aerial on the roof or somewhere high that's on the transmitter side of the building. Then have the signal split to feed the various TVs. Get decent cable installed too - WF100.

 

[leevis]

I hear ya, i am that close to doing it

However, i have bought a new aerial (mini one) and was testing it using my aerial tester and cable that came with it and got a very low signal.

My question is should my signal be stronger as i am close to CP.

Obviously its dependant on a number of things but i was hoping for a stronger signal than i am getting, i have even used my camping aerial that it much larger and still i only get one bar.

This is when i hold the aerial above head height, on the roof it will be much higher i guess but how much i don't know.

 

[Sam Gangee]

Point your aerial through a bedroom window towards Crystal Palace.

See http://www.satcure.co.uk/tech/best_aerial.htm

And note that Crystal Palace needs a "GROUP A" aerial, NOT wideband.

 

[Lucid]

I hear ya, i am that close to doing it

However, i have bought a new aerial (mini one) and was testing it using my aerial tester and cable that came with it and got a very low signal.

My question is should my signal be stronger as i am close to CP.

The real question is how good is your aerial tester.

In addition to my Horizon pro installation meter I carry a budget SLX meter. and one of the It's useful for showing folk Fringe Pro+. They're useful for showing people the difference in accuracy between domestic gear (SLX & Fringe Pro+) and proper professional gear.

The SLX isn't that sensitive. I'm about 30 miles from Winter Hill. It's a 100kW transmitter in the North West. So, I'm double the distance from a transmitter that is only half as powerful as CP. I have a large Log Periodic on the roof. There's no amp, so the signal is "as is". I use good cable; marginally better than WF100.

On my professional meter the channel strength is 60~62dB from weakest to strongest Mux. On the SLX I get one bar (50dBuV). So the SLX isn't that sensitive. It has a very course scale; 10dB increments is too large a jump for fune tuning aerial position. Also, it under-reads by at least 8-10dB. It's a very rough and ready tool.

Before you go any further, make sure you're using WF100 cable. If you have some cheap (or not-so-cheap) 'low loss' coax, or worse still the aerial extension stuff sold with moulded plugs on the ends then return or bit it. It's crap. I've been to more problem installs where the signal loss is purely down to that rubbish than I care to remember.

Here is decent cable: http://www.satcure.co.uk/accs/page8.htm

Put your plugs on correctley; here's how: http://www.satcure.co.uk/tech/tvplugs.htm

I would expect your signal strength to be lower because of altitude, room/house position, and the lower signal strength because of the aerial being shorter. On the flip side, CP is the UK's most powerful transmitter and you're much closer to it than I am to Winter Hill. All-in-all the factors probably balance out. 45-55dBuV is plenty of signal at the back of a TV to get decent reception. Signal power is less important though than signal quality.

 

[leevis]

I think that its the cabling. When i installed it i just used cheap stuff sadly.

Problem i have now is that the powered splitter is in a cupboard in the loft extension so the wiring is likely to have to be removed and done externally which is a bit of a blow.

When i 'test' the aerial, i only get one green bar which is telling me that something isn't too great there. I there a way to check the aerial strength directly from the aerial? would that be done by using a small bit of coax a testing it directly? I might have to do that to totally discount the aerial. As i said i think its the wiring quality/lengths etc

Next time i get up there i will test it to see if it is the aerial, best case it will show only one bar on my tester and i will replace and get more bars but i think i am dreaming.

 

[Lucid]

Did it not register, what I wrote before?

You ain't gonna get more than one bar because the tester just isn't that sensitive.

 

[leevis]

It did register. I am sure i had more than one bar on my tester before. This is why i think i need to test the aerial itself just to discount it. I am pretty sure that its the cabling because it was the cheap stuff.

 

[Sam Gangee]

So why not connect your meter as close to the aerial as you can?
That's what a professional would do to get the most accurate reading.

But bear in mind - as Lucid stated - that your meter is not accurate so all you'll get is a comparison. And it might still be one bar.

 

[leevis]

Thats what i am after, a comparison. Its either going to go well or it isn't (i presume it isn't but it may do). Are aerials tested using a small bit of coax or can you do it with a fly lead?

 

[Sam Gangee]

Test the aerial with a SIGNAL METER.

 

[Lucid]

With some decent coax (Webro WF100) then the losses per metre for a short fly lead are... a) known ... and b) negligible. (0.15dB/m)

The effect of a short fly lead is negligible compared to the coarseness of the measurement scale on your meter. Your meter measures in 10dB increments.

The other problem is the measurement range. It starts at 50dB and goes up to 80dB. The range starts too high (50dB) and ends too high (80dB) to accurately reflect the sort of signal levels from a properly aligned aerial and correctly-set distribution system.

I'd expect to see about 55~65dB at the aerial mast either direct or after the masthead amplifier. i.e. before the cable run down in to the house. The same signal then measured at the TV after it has run through the distribution system will lose some power and pick up some noise. I'd be looking for around 45~55dB at the TV.

The problems with the basic SLX meter are:

1) questionable accuracy - If my sample is representative, then it under reports its measurements by 8dB

2) 50~80dB measurement range was better suited to the old analogue TV system. The power levels were higher. Digital transmissions run on lower power. For domestic DVB-T/T2 use the meter should have a scale of 40~70dB

3) 10dB increments are too coarse. TVs with a Freeview tuner can overload with too much signal. That's as bad a problem as too little. 5dB increments would be more useful. Just a couple of dB difference can make or break a system.


So, by all means measure at the aerial. But bear in mind that 50dB on the meter could easily be 58dB off the aerial. You're not going to get much more than that off an unamplified mini log. So you're chasing this extra LED on the meter when it's highly unlikely that the aerial can provide it and the meter can't reflect the signal accurately either.

There's a phrase that sums this up.... 'Flogging a dead horse'

 

[winston1]

Indoor aerials only work for 10% of installations. Amplifiers on indoor aerials are a waste to time, money, and electricity. Amplifiers are designed to overcome the loss on a long run of cable which you don't have on an indoor aerial.

S as has been said get in a professional.