Reflected mullaghanish dtt signal

pegasuspub

A house call to 17 year old Panasonic tv revealed LOPT failure,the house had an Antiference LP7 vhf aerial atop of a 20 foot mast on the chimney,it was always a very poor place for reception,Installing a new LCD tv provided grotty vhf analogue reception,the customer wasnt happy and over an hour was spent with a triax 52 element group a yagi and triax uhf masthead amp trying mullaghanish dtt and mt gabriel uhf analogue,both were no use.A quick walk up the hill behind the house with a meter and uhf grid aerial revealed perfect dtt and analogue reception 120 meters up the hill,walking back down i decided to check signal every 20 meters, i found by chance a excellent mullaghanish dtt signal on channel 21 with the grid aerial aimed south at a large hill in the opposite direction to mullaghanish,i tried again in front on the house and found the same signal quality,going back upto the chimney proved the signal was getting worse but by keeping the antenna low down,aimed to the south(when mullaghanish is due north)and using the hill and the house to shield the aerial from direct dtt signal,the aerial was bolted to the gable end 8 ft off the ground,10 meters of cable and a new uhf mast head revealed excellent dtt signals,tuning in tv3 and tg4 analogue from mullaghanish revealed severe ghosting,and hopeless analogue reception form the same aerial.This was 2 weeks ago,we decided to leave it on trial in case the recption varied or failed as some sort of freak,the result so far is a delighted customer whose family cannot believe the reception is not coming from a dish each time they visit?

The Cush

As we have said here before "RF Reception Really Is A Black Art....".

watty

DTT is designed that "ghosting" boosts the SNR.

My TV is useless with aerial on chimney. The Analogue pictures look like Sky Digibox with 13 element just above back door on gable end.

Seeing the mast UNDER the boughs of the Giant Mature beech trees

gtg60

Black art indeed!

I was fitting a combo box in the father-in-laws a few weeks back and had an old contract CD and was trying it out in the attic, best I was getting from Kippure on channel 54 was 16~18dB no matter where I tried, got tired so rested the aerial on the (plastic) water tank, happened to look at the meter and it's 33dB! And that's where it still is!

Mike 1972

Heard a story (possibly urban legend) about a guy who moved to Glenties (Co Donegal) in the 1960's and spent four days on a rooftop trying to get a TV signal (ANY TV signal)

eventually in total frustration he chucked the aerial off the rooftop where it landed in the front garden and in came a signal (RTE ? UTV ?)

Sam Russell

Mike 1972 wrote: »

Heard a story (possibly urban legend) about a guy who moved to Glenties (Co Donegal) in the 1960's and spent four days on a rooftop trying to get a TV signal (ANY TV signal)

eventually in total frustration he chucked the aerial off the rooftop where it landed in the front garden and in came a signal (RTE ? UTV ?)

The big problem in the 1960's was the terrible TV designs they had then. The antenna has hardly changed since, but the sensitivity and selectivity of tuners is beyond comparison. So is the level of interference. There was no co channel then because there was only a three channels: BBC, UTV, RTE.

http://www.boards.ie/vbulletin/showthread.php?t=2056032750

That thread is another example of signal reflection