bbc NI 1&2,utv and channel 4 on television using indoor aerial in laois

markmiller321

I got bbc, utv and channel 4 last weekend in laois/carlow area with an ordinary cheap indoor aerial last week . The picture and sound was fairly good with just a bit of dandruff like interference. Its gone now. Anyone know anything about this and how to get them back.

channelsurfer

not sure remeber years ago We used to pick up utv on an old indoor tv because it used to come from the cable system overflow could be that.

bigpaddy2004

markmiller321 wrote:

I got bbc, utv and channel 4 last weekend in laois/carlow area with an ordinary cheap indoor aerial last week . The picture and sound was fairly good with just a bit of dandruff like interference. Its gone now. Anyone know anything about this and how to get them back.

Mark if you are in a cable tv'ed town just like Portlaoise which is still using the standard 'basic cable' system, you could be picking up someone whom is using one of those wireless repeaters to supply tv around there house without the need for wires.

lawhec

markmiller321 wrote:

I got bbc, utv and channel 4 last weekend in laois/carlow area with an ordinary cheap indoor aerial last week . The picture and sound was fairly good with just a bit of dandruff like interference. Its gone now. Anyone know anything about this and how to get them back.

It was probably tropospheric propagation - there were fair conditions last week, I managed to listen to FM 104 clearly with a portable for a couple of days here in Tyrone! This happens usually during a period of settled weather. In Spring, Summer & early autumn this happens when the weather is generally sunny and dry with mist forming at night, while in the winter it is just rather foggy. What happens is that the warm air mixes with the cool ground and forms an inversion layer several kilometres above the ground. This layer allows VHF and UHF signals that are usually sent skyward in space are instead reflected back down to earth and can be received well beyond the main service 'line of sight' area of the transmitter. The factsheet from the BBC in the link below gives a good description of this.

http://www.bbc.co.uk/reception - click on factsheets and go down to the bottom - how weather affects reception.

I would say it would be unlikely in your location to be able to have a consistent reasonable reception like what you had there on a regular basis even with large outdoor aerial setup, unless AFAIK you have a reasonable line of sight towards Wales.

bigpaddy2004

So Northern Correspondent, is this the same pheonomon which happens to cb radios which allows people to talk all over the world on ssb channels?

Something similar.
If you look at the weather forecast especially in the summer and you see an area of high pressure over Ireland and Britain, you will get troposheric ducting of signals.
It all depends on the location of the hp cell though and it would have to cover the area where the signal is coming from and your location with more or less the same high barometric pressure.
It usually works better at night time.

Mossy Monk

i remember when in Dungarvan i was watching the BBC News from Birmingham a few years ago through the tv aerial. Odd but it lasted a while. BBC Wales, West Country tv (which i can get a dodgy reception of anytime in the year with a combination of the UHF aerial i have for a deflector and rabbit ears) is very common. also quite common in the summer months is Spanish radio on the FM band. i havent managed to pick up Spanish tv but have heard of someone doing it on what was probably DS

Mike 1972

tropo ducting is often confused with sprodic E

Sporodic E brings in Band 1 and FM signals from Iberia, Italy and the Nordic countries during the summer

Tropospheric is more weather dependent (high pressure) and brings in FM Band 3 and UHF stuff frim closer to home i.e. Ireland and the UK

lawhec

bigpaddy2004 wrote:

So Northern Correspondent, is this the same pheonomon which happens to cb radios which allows people to talk all over the world on ssb channels?

I don't be involved with CB radio but I would imaginethe answer is no - troposhperic propagation generally works best it seems from VHF Band II (FM radio) up to the top of the UHF Band though it could also work on lower frequencies as well and is very much a single - hop operation i.e. it only reflects off the atmosphere once. This is limited to around no more than 500km.

I do know that VHF Band I signals at times, occasionally Band II and on very intense occasions even the lower part of Band III, can be carried by Sproadic E where the signal reflects ofthe E layer of the inosphere which is much higher up than the troposphere. A maximum useable frequency (MUF) determined by how electrified the layer is allows high HF & low VHF signals to be reflected - as the 27MHz CB Band is below VHF Band I it would probably travel quite well. Distance is usually no more than 1500km, though it can be more if there is a multihop path available whereby the signal is reflected off the E layer down to earth, reflected by the earth back up to the atmosphere and reflected back down again from the E-layer. Two years ago there was a great case of this where several FM radio station in the USA and Canada could be heard in parts of Northern Ireland and Scotland - it was a double hop where the Atlantic Ocean made a good earth reflector.

The last main one is F2 propogation (higher up than the E layer still) which is heavily reliant on the sunspot cycle and has not been known to propagate above VHF Band I but in the right conditions distances can carry signals great distances - there's many stories of how BBC Television from the 405 line days was receiveable in South Africa and Australia thanks to F2.

So my guess is that if CBers are being heard around the world, it must be via F2. Unfortunately we are now heading into a sunspot low which won't start picking up again for another few years.

Antenna

Mossy Monk wrote:

i remember when in Dungarvan i was watching the BBC News from Birmingham a few years ago through the tv aerial. Odd but it lasted a while.

I suspect this could have been coming through a deflector - because the large transmitter near Birmingham (Sutton Coldfield) uses the same frequency channels as the Welsh transmitter (Presely) 40,43,46,50 that feed/fed deflector systems. This would occasionally cause noticeable co-channel interference (Cable systems affected also before they transferred to microwave feed of Northern Ireland TV received up the country) - though on very rare occasions (perhaps if Presely was also on reduced power) it would briefly dominate the channel, - I have seen this happen in the past when I was watching deflector signals originating on the Comeragh Mountains in Co. Waterford - 'Central TV' logo briefly came over HTV on one occasion.
Years ago (1988 I think) before HTV went 24hrs a day I recall seeing Central TV from Birmingham (which at the time unlike HTV was on all night) fading in with a watchable picture at times on the deflector TV network overnight!

Speaking of long distance reception I also recall an incident around 1988-1989 where I managed to get TVE2 from Spain somewhere at the low end of UHF due to very long distance 'ducting' (without sound of course due to the differences in TV systems) - this was the only time I have managed to receive Spain at UHF. This with a horizontal polarised colour king aerial with preamp for a deflector in a different direction. Just one small hill about halfway between me and the sea.

Capt'n Midnight

Back in the days of VHF Band I they could sometimes pick up TV from Crystal Palace down in South Africa.