Summary

User posts from uk.tech.digital-tv reveal widespread reception problems with OnDigital's COFDM-based service in the UK, including signal breakups caused by passing cars and electrical interference. Professional antenna installers and OnDigital engineers alike struggled to resolve intermittent failures, undermining claims of COFDM's superiority over 8-VSB.

Source document circa 1999 preserved as-is

COFDM Vs. 8-VSB SERIES...

  

And In The Real World...

 

Mitch Cardwell" forwarded to my Email box this collection of posts from England, where COFDM has been installed.


Mitch Cardwell: These are post I pulled from uk.tech.digital-tv. So before we go and declare COFDM/DVB to be our savior maybe we should consider eliminating light switches, moving cars, and car ignitions.

NOTE: Some of these people have MASTS! with line of site to COFDM transmitters and are having problems. Another post is from a professional antenna installer. Others have had OnDigital engineers in their homes who couldn't make it work! And one guy is getting a good signal from Crystal Palace, their freakin' flagship transmission center and is having breakups and freezes when cars drive by.

Mitch

Hiya,
I'm new here, so this may not be a new problem but...We got OnDigital a couple of months ago. Our whole postcode area is listed as OK. We bought and fitted a wideband aerial, as the dealer suggested - alignment is easy as we can see the transmitter. On some channels - mainly the lower-numbered ones such as the BBC and ITV ones - we are getting a lot of picture break-up, but this appears to be randon and occurs more during the day than in the evening.

OnDigital sent an engineer out today (actually an engineer from Granada), who checked our signal strength and said it was fine. On the on-screen thing on the Pace box we get between 2.5 and 3 on all 6 channel numbers. The engineer thought the Pace box was at fault (he said they are prone to this sort of thing) but despite his squeezing the thing to prove his point it wouldn't play up. As I said it's intermittant and today it was working fine.

So I phoned OnDigital, who eventually put me through to an engineer. He went through the signal strength checks etc with me (this is the third time we've been through this with them), decided they were OK, then asked me to squeeze the box at the back around the SCART sockets etc. Nothing changed - by this time BBC2 was looking a bit so-so fortunately. He said he'd speak to someone and phone back.

20 minutes later he was back. The "senior engineer" thought our signal could be too high, and suggested we buy a 6dB attenuator. I did, and nothing changed.

I phoned back yet again, and got yet another different engineer! He started going through the same signal strength crap again, until I told him we'd already been there. I told him who I had spoken to the previous time, what had been suggested, and that it hadn't worked. He also didn't think the box was at fault, and said he'd call back. He didn't.

We have now basically given up in disgust over the whole situation. I have phoned OnDigital and told them I am cancelling the contract (someone will phone me back to discuss this....) and cancelled the Direct Debit.

The trouble seems to be that there is no one person they can send who can sort everything out. Granada could only check the aerial installation (we didn't get the system from them) and blamed the box. OnDigital say the box is fine and point the finger at the aerial installation, and when told that Granada say the aerial is OK they don't know what to do. The whole thing is an utter farce!!

It has cost us a tenner for the aerial, about £15 in phone calls to then (3 hours at 8p per minute), £3.50 for the attenuator. and thirteen quid a month for two months for the subscription to a service that never seemed to work when there was something we wanted to watch. I will be trying to get OnDigital to refund this lot, but I'm not holding my breath!!

Granada will be installing a Sky Digital system for us in about 3 weeks. We will miss Carlton World, but I'm sure the gathering of Discovery channels will make up for that!


Paul.

-- Paul Stenning, Hereford, England


As aerial fitters for the last 25 years or so, we have also been beating our brains out over some Ondigi fittings where the signal strengths are OK, there are no Ghosts, and the aerial has no amplifiers (another thing that the Ondigital people like to accusse of being the problem). We are now on the point of either:

A) Refusing to touch Ondigital work at all, (we don't supply boxes) or:

B) doing aerial work for Ondigital sets on the basis that, if we are called back for "intermittent" problems, we are paid for a callout every time, either by the customer or OnDigital.

We have found that we are often called back endlessly for "faults" which are intermittent, and which we are not responsible for - it's the damn boxes, by Ondigital are very loath to admit it.....

Two things we have found that can affect the reception in the way you say are:

Interference from passing motor vehicles with powerful electronic ignition systems. Customers living on busy roads have many more problems, in our experience. Picture freezing is common in this circumstance.

Mains-borne interference (fridge thermostats clicking on and off, Black and Deckers next door, etc) also seems to affect some boxes. A proper mains filter adaptor can help - but they're dear - £20 upwards! (And the customers don't want to pay).


- Rod Buck

Maybe I've been lucky but I have managed to get a pretty good installation sorted out for the OnD box. I have a wideband antenna stuffed up in the roof space(which was there to pull in a v.weak Channel 5 signal) & a 23dB wideband( & as low noise as i could get) masthead amp (added for the digital setup replacing a 15dB set back). As the cable emerges at the wall socket I have fitted a ferrite core (salvaged from a PC monitor cable to suppress spike rf interference ) wrapped on the cable and another before it enters the box. Seems to work pretty well. Went from signal at 3 on 3 of muxes and sod all on the other 2 up to 5 on the two higher power ones and 4 on the lower powers. Still get minor intermittent interference from one of my light switches, but not as bad as with the set back installation, and RF from the neighbours car ignition seems to be gone altogether.

Kevin

Me, as they say, too. I have a good signal (4 green) from Crystal Palace on all MUXes including the MUX I'm not supposed to be able to receive (MUX D) according to the DTG coverage prediction page. I've always had a good analogue signal and even had excellent Channel 5 coverage (analogue on Ch 37) before they turned up the wick on the C5 transmitter in Croydon.

I do however see a lot of what looks like ignition noise. Certain cars going past cause breakup (often with a loud audio "click") and even on a couple of occasions have caused the picture to freeze permanently. I tried ONd Customer Services, who took me through looking at the signal strengths and declared that it was "possibly a problem with the STB" (A Philips, by the way). I'd happily take it back and complain; I don't know how much joy I'd get at Currys' though as talking to them about MUXes and signal/noise ratios would probably be a complete waste of time. I expect they'd just tell me to go and get a new aerial. I'd be happy to pay an aerial contractor if this would fix things but I'm loath to pay for a new aerial and fitting then find that the problem was the STB all along.

To be fair, I've also seen a *very* slightly noisy picture on analogue when the bloke across the road fires up the bike he's restoring - I don't however see noise on analogue anywhere near as often as I see breakup on digital. I'd say I see digital breakup perhaps 20 times more often than I see analogue noise.

Has anyone any ideas on how best to localise the problem to either the aerial or the STB? If a couple of ferrite cores would do the job then that would be great. Alternatively is there any future in trying to get Currys to agree that if I try a new aerial and this doesn't solve the problem then they pay for the new aerial?

-- Tony

Advanced Television Publishing
1999