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[mywifeshusband]

Can anyone please define Signal Quality a against Signal Strength. My antennas are pointed to Hannington 23 miles away broadcasting a freeview signal on Channels 50, 43, 40, 46, 44, & 41 Although Hanninton is not due for conversion until February 2012 I get a medium Freeview signal strength on these channels. Similarly a medium signal quality on these channels except for 46 which is no higher that 2%. This via a a Sagemcom DTR6400T digital receiver & recorder and a high grade multi element wideband antenna with mast head amplification. 
However in a seperate room I have a LG computer Monitior cum TV with a very old and low grade non amplified antenna I get pretty well all that is available including Channel 46 at good quality. Is there an explaination I wonder. If so can someone please point me in the right direction?

[tonyappuk]

The indicated signal strength and signal quality indications will have been defined by Sagem or whoever made the receiver/decoder for them and it's very difficult to know what their intentions were. In particular the signal quality indication I would surmise looks at decoding errors or the amount of error correction being applied. The effect of a low quality indication on the picture would be the usual pixellation/static blocks you get and this will also occur with low signal strength anyway. The differences between the two receivers working off different aerials would point to one of the aerials being faulty. In your shoes I would swap the two receivers over so that each is using the other's  aerial and note the different indications. This should establish if it is the aerial at fault. The other thing that strikes me is that at 23 miles I'm surprised you need a mast head amp but you could be in a dip or a shadow of some sort but the performance of your computer set up would suggest that signal strength is quite high. This leads me to wonder if the signal from your amplified aerial is too high and is overloading your receiver. You could try an attenuator in the aerial lead of about 6dB.
Tony

[mywifeshusband]

Thanks for your reply. I don't think it can be an antenna problem but I might be wrong. Both antennas give a full block of little white boxes when tuned to cefax page 284. I have tried swapping the antennas and this certainly added a few more channels to the Sagemcom DTR6400T digital receiver & recorder but it did not capture anything from channel 46. I am yet to try the LG TV PC monitor on the 'better quality' antenna and will report back any improvements. I'll also take out the amplifier and see if this makes any difference.
Thanks again.

[exo]

I also receive transmissions from the Hannington transmitter. I reside southwest of Andover, so a similar distance as you from the transmitter.
My signal strength and quality is at maximum (both showing 10/10 from a LG and Panasonic LCD TV).
More to the point though, does your picture break up with pixelation / large blocks?

Hannington has quite a transmission screen/cut off to the north east in order not to interfere with the Guildford transmitter.
Could this be a problem as you do not mention where you reside.

I am also surprised you need a masthead amplifier. If you are receiving a poor signal, then you will amplify a poor signal which will make matters worse.

If reception is a problem, then I am not an advocate of using a wideband aerial.
Specific B or E aerial (Yagi is good) for Hannington may be better. If you need to replace, get the B as this will be slightly better after Feb 2012.
Also, what is the definition of a high grade multi element. If just a "Contract" or one purchased from a DIY Superstore, then the quality may be suspect.

Last but just as important, is the quality of the cable. I suggest using quality screened satellite cable with F connectors.


This site gives valuable information and may help with your problems.
http://www.aerialsandtv.com/hanningtontx.html

exo

[mywifeshusband]

Thanks again for your suggestions.  The problem has been located but the reason remains a puzzlement. Removing the masthead amplifier gave me a medium to good signal quality on all Hannington channels, including Channel 46. However without the amplifier the signal strength over all Freeview channels fell right back into the bottom part of the poor quadrant. So the wideband antenna and amplifier has to stay at for the time being until I can get hold of a good Type B antenna and do some more testing.  Analogue TV works OK without the antenna except for Channel 5 but freeview is unwatchable and almost non existent.
I'm still puzzled though why the amplifier should just knock back the signal quality on Channel 46 whilst leaving the others unaffected. Then Yes I am about 7 miles from Guildford on a bearing of 93 degrees from the transmitter 23 miles away: and take your point about the problems that might ensue, so having done some reading on this already, I think I need to do a bit more to be quite sure of my next step. Thanks again though for the pointers and links.

[roseway]

It may just be that the masthead amplifier has poor performance at that particular frequency. I have to use an amplifier here to get good quality Freeview (although mine is in the loft), and I did find that similarly specified aerial amplifiers had widely differing performance in actual use. The one which worked best was one which a friend was throwing out because it performed poorly in his situation.

The best option for sure (in my opinion) is to get a high gain narrow band aerial covering just the requisite channels.

[tonyappuk]

mwh If the mast head amp is truly at the mast head and not at the end of the aerial cable I wonder if you are actually removing it or removing the power feed to it. If the latter you will certainly reduce the signal amplitude but not by just a bit but a lot. An attenuator would be better. The reason Ch 46 is showing poor quality with the preamp is due to overloading I believe and reducing the signal strength stops this. You need to find the right level of signal.
Tony

[mywifeshusband]

mwh If the mast head amp is truly at the mast head and not at the end of the aerial cable

Oh yes I did the job properly! - and  without breaking my neck. Afraid though further adventurous excursions of this nature will have to wait until the grandchildren have gone back to America after Easter. Thanks again to all who contributed anything.

[tickmike]

mwh If the mast head amp is truly at the mast head and not at the end of the aerial cable

Oh yes I did the job properly! - and  without breaking my neck. Afraid though further adventurous excursions of this nature will have to wait until the grandchildren have gone back to America after Easter. Thanks again to all who contributed anything.

I moved my aerial to the gable end wall from the chimney to save me going on the roof, It's about the same height because I fitted it on a 2" Dia aluminum scaffold pole on two strong brackets.

[broadcast]

nice discussion...........