Freeview DXing

[crusher19860138]

Hello,during the 1970's/80's and right up to 1998 when On-Digital started,we used to be able to pick up BBC1 Wales and HTV Wales via Moel-y-parc,using a high gain aerial and mast head amplifier,in those days,it was worth having another region!iam about to try this feat with my Freeview box,is it possible to pick up distant transmitters in this,the digital era?how sensitive are they?

[Neil Purling]

I think you are wasting your time, as poor signal strength totally ruins a digital broadcast far sooner than any analogue signal, The picture breaks up into random pixels and the sound as well.
This regularly happens with the lesser channels of Freeview, even with the local transmitter: Belmont.
We used to have a extra aerial pointing towards the Tyne-Tees transmitter at Bilsdale on the N. Yorkshire Moors.

[crusher19860138]

Thats a pity!what about when we have all gone digital and the transmitter powers are cranked up?i agree with you we have a local relay station about 1 mile line of sight from my location,and Freeview from it is very variable,even with a good aerial,the analogue is perfect!

[DrZarkov]

In the good old analog days it happened from time to time, that I was able to pick up signals from the transmitters in Tacolneston and/or Wrotham. (Both more than 450 km from here, but of course with the sea between the transmitter and my QTH.) As the digital signal is not that strong as predicted, "Mediabroadcast" is rising up again the power of some transmitters here, I've heard about receptions of digital signals from the quite strong transmitters in Wesel or Münster in the UK. So DXing became more difficult, but still possible. (Even if I had until now no luck in receiving UK-Freeview here in Germany.) The bigger problem is, that with the increasing number of transmitter the UHF-band is full here, there is not much space left for DX.
Don't forget that on the continent there are some digital transmitter on air on several VHF band III channels! Some freeview receivers are capable to receive them.

[julie_m]

Originally Posted by DrZarkov

Don't forget that on the continent there are some digital transmitter on air on several VHF band III channels! Some freeview receivers are capable to receive them.

This is true. I have a multi-standard (DVB / PAL B/G/I/ SECAM D/K / NTSC) set that will tune all the way down to 45 MHz, and it wasn't anything special.

Unfortunately, I live too deep in a valley to try any DX fun; but there must be people on high ground with suitable receivers.

[Boom]

I have an LG digital tv that tunes from under 50MHz to UHF with no gaps at all.
I should think this has been done for cheapness rather than expecting to find tv signals at such as 145 or 90 MHz.

[SteveCG]

I used to receive Wenvoe analogue UHF TV and Mendip analogue as fringe signals. However the Signal to Noise ratio from their digital transmissions was not good enough for digital TV. Since their switchover to pure digital I can watch Wenvoe on digital, with a little blocking, and Mendip is now good enough for DVR recording. Its not exactly DX TV in the Sporadic E sense, but it is better than I had expected. The digital threshold transition was about 1-2 dB wide in S/N terms, so either you get a good picture or as has been already said nothing at all.

[murphyv310]

Hi,
I can receive Black Hill digital here quite well and I am well out of the service area, not all of the channels of course but those on CH42 are mostly reasonable, the analogue signal though is quite poor.
I often can receive analogue from Divis in Northern Ireland but due to interference from Darvel (my local TX) cannot get any digital from NI. Perhaps when we switch off our analogue service from Darvel I will be able to receive digital from NI.

[marconimen1901]

Greetings Digital DX fans,

This thread reminds me that living on the edge of the Trent Valley in Scunthorpe, North Lincolnshire and in a flat within a highrise tower block, that television signals, are on the one hand cut out altogether by ferrous concrete and that on the other hand, they romp in from all directions, given a suitable, even set top aeriel!

When Freeview came along an engineer from Hull, in establishing cabled television to the roof of the 160' high tower block, itself already a similar distance high, from the valley below, was inundated with digital signals, from Emley Moor, Belmont, Bilsdale West Moor and from the two Midlands transmitters, one near Nottingham and the other at Sutton Coldfield.

"Which should I centre the yagi upon?" was his question to me!

We decided upon Belmont because like Emley Moor I can physically see them from the building, with Belmont the nearer of the two. Emley Moor is 53 miles as the crows fly, but on a clear day or night and even with my poor eyes, those red lights are unmistakable outside Huddersfield.

Sadly these days the only DX reception even at this vantage point and assuming the closure of the analogue service, will reveal local news, which will identify along with the frequency in use, the service to which you are tuned.

The portable, (in a leather case and strap round his neck to carry it), aeriel tuning set, that the engineer used was totally overloaded with digital clutter, to the extent that in the end, he actually used attenuation on the other frequencies, band pass only to Belmont and band stop to the rest.

I cannot help but feeling that the freeview platform encompasses all of the worst aspects of analogue and few of its good points. Not everybody lives in the clouds or gets up in the morning for 0600-1400 shifts at Scunthorpe steelworks, putting on US East Coast AM on the medium wave with some regularity.

Perhaps if we all fly around in aircraft doing our dxing, that is what the digital service was intended for. As with analogue AM radio I would have preferred to see the preservation of the AM service not its demise!

Best wishes to all.

DAVID

[Hermit6345]

In Corsham, North Wiltshire, I can receive a beautiful picture from somewhere in the Southwest, I assume it must be Beacon Hill. The nearest transmitter to me seems to be Stockland Hill but I would imagine that its aerials would be favouring south and southwest rather than this direction. It's interesting watching regional programs like Spotlight instead of Points West.



Ian

[terrykc]

Over on uk.tech.digital-tv Freeview DXing, though not referred to as such, is causing lots of problems for some and is predicted to get worse as ASO spreads over the country with the consequential vast Tx power increase.

It looks as if there is something important missing from the Freeview spec which will be an ongoing source of problems ...

It works like this: you live in an area served by a Group B (or C or D, etc.) transmitter. When you tell the STB/PVR/DTV to do a scan, it picks up weak signals from a Group A transmitter first, because it always starts its scan at channel 21, and logs all the channels. When it gets to the local transmitter, with much stronger, error free signals, it doesn't recognise them as being the local, wanted, signals, so it stores them as additional channels above the original Group A channels with numbers in the 800s[1] ...

The user then finds that reception quality has plummeted with all sorts of problems, from blocking to no pictures at all.

The only way to resolve the problem is to unplug the aerial and start the scan, watch the channel numbers increasing on the screen, then plug the aerial back in sharpish before it gets to the first channel used by the local transmitter.

Hardly user friendly, is it?

How many little old ladies know which channel numbers are in use, let alone follow this arcane ritual? In fact, how many of the general public know anything at all about this?

As ASO works its way round the country it will take in increasingly more populated areas and, the later ASO happens, the more high power DTV transmitters there will be around the edges.

As ASO demands two retunes on fixed dates of all sets in any given area, I can see chaos looming - and lots of money to be made by the unscrupulous ...

Not content with the 'digital aerial' scam, the latest promotions are for 'HD Aerials' ...

It'll be 3D next ...

[1] I think they start at 800 but being 18km from Crystal Palace (Group A) I don't get this problem ... and never will ...!

[Peter.N.]

I thought my experience with digi may be of some use to you. When it first started from Stockland Hill on low power it didn't expect very good results in many places due to the hilly terrain in this part of the country but was pleasantly surprised to find that a good digi picture could be obtained in some places where analogue was almost unusable, although not necessaraly on all channels.

My own TV is a Sony analogue/digi set which worked very well initially, the only thing we were still using analogue for was video recording. One day the signal almost completely dissapeared from the VCR, I then discovered it was missing from the TV also, two stations were completely blank and the others showed a very weak unusable signal. The reason for this? I went outside and looked at the antenna and found the end of the cable hanging down the wall, we had recently fitted a new barge board and it must have got broken then, it had no effect whatsoever on the digi signal, in fact I am ashamed to say its still in the same condition.

Peter

[KeithsTV]

Although I'm line of sight to Emley Moor I can receive the Winter Hill digital signals but not all of the multiplexes. Emley Moor is 12 miles away and Winter Hill is 28 miles away on the other side of the Pennines.

When I lived in Beaumaris on Anglesey we got our (analogue) TV signals from Winter Hill 80 miles away. It was literally line of sight with mostly a sea path. I wonder if digital reception of Winter Hill is possible in that area?

Keith

[Hybrid tellies]

Being a TV Dxer I have thought long and hard about this. Living near Bristol is not the best part of the country for UHF dx on analogue and on Freeview its near impossible. What we need is a box where you can quickly select an individual channel whist showing a signal strength bar so we can quickly tune through the UHF band pretty much as we do with analogue tuners. I think this is easily possible but just needs someone to build such a box with such features for us.

[terrykc]

I doubt that anybody is going to build your special box for you! I shudder to think what it might cost!

Your best hope is that like minded person will re-write the firmware in a standard STB to do what you require. I know that there are a lot of people out there who write special mods for Topfield PVrs, but I don't know if the RF front end is amenable to such hacks.

Why not find a forum for Toppy fans and ask there? You never know, someone might already have done it or, perhaps, be interested in taking up the challenge ...

The only suggestion I can offer in the meantime is to use a spare STB (to keep the peace!) and a pen and paper.

Do a scan and watch progress. Every time it stops to acquire info, jot down the channel number. Then, when it's finished, analyse the results in conjunction with an up to date transmitter list. The STB will add programmes in the order it finds them so, if you end up with three lots of identical programmes, you should be able to identify which one is which by the channel order that particular mux is on. Sounds complicated but it probably wouldn't be too bad once you get used to it.

[terrykc]

Originally Posted by Boom

I have an LG digital tv that tunes from under 50MHz to UHF with no gaps at all.
I should think this has been done for cheapness rather than expecting to find tv signals at such as 145 or 90 MHz.

Yes - probably a standard multi-band front end to cover all countries, including some where cable TV connects directly to the subscribers TV. Somebody couldn't be bothered to modify the firmware to make it country specific.

[PJL]

Just bought a plasma TV with HD receiver, and the freeview site advised I wouldn't be able to receive HD till 2012. Not the case at all, I can receive Crystal palace transmissions with no dropouts at all.

The receivers do seem to have improved quite a bit over the years. My antenna is an ancient old thing pointing at CP that was here when we bought the house some 20 years ago.

[Peter.N.]

Maybe use a masthead amplifier, cant think of anything else.

[SteveCG]

If I remember correctly (it is now some time since I did this) my Alba DV Recorder allows me to check the signal strength on a user chosen UHF channel. So my way of proceeding to get the TXs I wanted was first to wipe the DVR's channel memory by doing an auto-scan with no aerial attached and then check the signal strength of the UHF channels I wanted, and then (the crucial point) saving the channels to memory. Obviously I need to know the TX UHF channels first!

[G0MEM Michael]

Originally Posted by terrykc

The user then finds that reception quality has plummeted with all sorts of problems, from blocking to no pictures at all.

The only way to resolve the problem is to unplug the aerial and start the scan, watch the channel numbers increasing on the screen, then plug the aerial back in sharpish before it gets to the first channel used by the local transmitter.

Hardly user friendly, is it?

It's not user friendly at all. I ran into the problem myself when I was living in a higher part of Bristol. The Freeview box was picking up a weaker relay on group A while my strongest signal was on Mendip C/D. That's exactly what I had to do to make the box tune properly. Unplug the aerial then quickly plug it back in when it scanned the C/D channels.

BTW I can confirm that Freeview DX does not work, as I can't receive Freeview at all from my current location.