625 - Andrew Wiseman's Television Room
PDC (Programme Delivery Control) Explained

Version 5.6a  Tu 2-Dec-03

Many new videos on sale today have Nicam, VideoPlus+ and PDC. Most people have heard about the first two, but what is PDC? Well, it's the amazing invention that enables you to set your video recorder to tape a programme, knowing that it will be recorded in full, even if the programme is shown later than advertised.

If you are about to buy a new video with PDC, you might want to check the Summary of Videos table below because some models are better at PDC than others!

If you already have a PDC video and don't live in the Border, Grampian, Granada, Scottish, West Country, Yorkshire or Tyne Tees areas you might want to write to your local ITV company to ask them why they are not broadcasting a PDC service. If you live in Wales, you might like to write to S4C too, to ask them the same question.

I'm grateful to all the engineers who patiently explained the technical stuff to me in terms I could understand. I hope you find this page both useful and comprehensible.

Contents

Click on this icon top below to return here. Items marked Rev. 5.6 have been updated since the previous edition.

What is PDC?

Programme Delivery Control, PDC, is a system that controls suitably equipped video recorders by using hidden codes in the teletext service. With PDC, if a TV show you want to tape is delayed or re-scheduled, the video recording will automatically be re-scheduled too, so you don't miss any of the show.

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How it works

Each TV programme has a Programme Ident Label or PIL. This label contains the date, channel and start time. Just before the programme begins, the broadcaster transmits a PDC code containing the PIL, which causes the video to start recording. This signal is transmitted, once per second, throughout the programme.

So instead of using its clock, the video uses the PDC signal to decide when to start and stop recording. This way you don't have to worry if everything is running late - the programme still gets taped.

The video sits and looks out for the PIL some time before the start time it is programmed with. (A programme can start early as well as late!) If it is programmed to record from more than one station, the video will channel hop, as necessary.

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How to program a PDC video

Most videos

PDC videos can be programmed in the same way as ordinary machines: "manually" or (if available) with VideoPlus+. The BBC recommends you program the video by taking the published start time or VideoPlus+ number from a weekly listings magazine. It's usually these times that are contained in the broadcasters' PILs. (The end time isn't so important for programming, since it is not used in the PIL.)

StarText videos

Some PDC videos can also be programmed by selecting the TV show directly from the teletext listings page with a cursor. These machines tend to be more expensive because they contain a teletext decoder. This method does have the advantage that it's easy and you don't have to have a magazine to hand. It's also far more accurate.

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The difference

When programming a PDC video manually the video determines the PIL it will look out for from the date, channel and start time you give it. Similarly with VideoPlus+, the PlusCode is decoded to determine the PIL that the video will use. This can cause problems. For example if a programme was originally scheduled to be broadcast at 20:00 when the broadcaster had determined its PIL, then 20:00 will be the start time used. If however, the show was then set to be moved to 20:30 before the weekly TV magazine was published, its pages will show 20:30 as the start time. So, no matter if the show actually starts at 20:30 and you program your PDC video with this actual start time, your video will not tape the programme because the PIL broadcast contains the time 20:00. To get around this problem, the Radio Times always indicates the start time (and corresponding VideoPlus+ code) used by the broadcaster to determine a PIL wherever it differs from the latest known actual start time.

With a StarText/PDC video recorder, you don't have to worry about knowing a VideoPlus+ code or whether the listings contain the same start times as used by the broadcasters when they determined the PILs. What happens is when you program using the teletext page, the PIL for the programme you're taping is actually looked up. The PIL for each programme is hidden from view, below the bottom line of the teletext page, where it can be accessed by the video during programming. This way, the teletext page can show the latest known start time whilst the video can determine the correct PIL containing the original start time. The drawback of this system is that because the teletext services only carry listings for today's and tomorrow's TV, you cannot program your video a week ahead, say.

Of course, if your video is equipped with PDC, but the TV station is not broadcasting a PDC service yet, then whatever programming method you use, the video will only be able to turn on and off at the times it is programmed with, thus missing parts of programmes that run late.

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IMPORTANT! How NOT to program a PDC video

The most common mistake to make when recording with PDC is to forget that it works on a programme-by-programme basis and that it ignores the programmed stop time.

Remember: if you want to record two or more consecutive programmes you must set the video for each programme individually.

For example, if you want to tape Friends from 21:30-22:00 followed by Frasier from 22:00-22:30, you might set the start time to be 21:30 and the stop time to be one hour later, 22:30. Normally you would expect a video would tape both programmes. With PDC enabled however, the video would assume the start/stop times applied to a single programme and since it ignores the programmed stop time, you would only get Friends on the tape and not Frasier.

If you use VideoPlus+ or StarText to program your video, it's not possible to make this mistake, since both systems work on a programme-by-programme basis.

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What is VPS?

VPS (Video Programming System) is used on terrestrial channels in some European countries (e.g. Czech Republic) and also on some of the channels on the Astra satellites. (See below for a list.) VPS videos usually have a 4-character display, which shows the channel name.

The VPS data is in the same format as that of PDC, but is broadcast in a different way. (For more details on this see the technical section below.) PDC is a newer and slightly more advanced system than VPS.

Some, but not all, of the PDC video recorders sold in the UK will be able to decode Astra's VPS signals too.

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Availability of PDC

Which channels are broadcasting PDC?

Currently in the UK, BBC One, BBC Two, Channel 4, Five and seven ITV companies - Border, Grampian, Granada, Scottish, Tyne Tees, West Country and Yorkshire are broadcasting a full PDC service.

This means viewers in Scotland now have a PDC service on all five terrestrial stations (although the BBC service remains experimental there). But the story for viewers in Wales is not so good - S4C have no plans to broadcast PDC and HTV talk of the system being obsolete.

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BBC

Both BBC One and BBC Two are now broadcasting a fully operational PDC service in the UK, except for Scotland where it remains experimental.

According to Radio Times the BBC's full service (non-experimental) began on Saturday 29th November 1997.

Before the Ceefax re-launch in November 96, page 697 forecast that BBC1's PDC service would begin in the Autumn of 1996. The same page had already unsuccessfully forecast Spring and Summer. The PDC page has now been removed from Ceefax and replaced with one on Digital Radio.

The main reason that BBC1 has taken much longer to begin its PDC service is to do with the greater number of regional opt-outs. Extra equipment is needed to cope with broadcasting a different PDC service for Scotland, Wales and Northern Ireland where they have their own regional programmes and, more importantly, time shift material (i.e. they show a programme at a different time from the main BBC schedule). The PDC codes for opt-outs are generated locally, and so extra time was required to fully test the equipment and train the local operators.

BBC2 also has regional opt outs of course, but this was originally dealt with by putting out the Timer mode flag (see below), which forces the video to revert to its internal clock for the duration of the programme.

According to the BBC's Promises for 1996:

The BBC is in the process of implementing this service. We intend to make it available on both our television channels as soon as possible.

On Thursday, 23 October, 1997, after a meeting with BREMA and other broadcasters, the BBC issued this statement:

The BBC believes that PDC can offer viewers with suitably equipped VCRs a convenient and reliable way of recording programmes, even if the programmes transmission time is delayed for any reason. There is currently an experimental service operating on BBC2 and an experimental service is planned to start early next month on BBC1, with a full service following shortly after.

Apparently, now that the service is fully operational on both channels, more care will be taken to prevent some of the problems seen with BBC2's experimental service - essentially more checks will be made to ensure that the correct PDC codes are being transmitted.

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ITV1

At one stage the ITV companies were planning a network-wide PDC system with regional opt-outs. It now seems as though the plan is for every company to fend for itself. So far, less than half of all the ITV companies have done this. Westcountry TV began its PDC service in early 1996 followed later in the year by Scottish TV. Yorkshire and Tyne Tees began at the same time in late 1997. Granada commenced its service in early 1999. The latest companies to begin transmitting PDC are Border and Grampian.

I have been told that the PDC indicator is lit when a PDC video is tuned to the following ITV stations: Anglia, Meridian, Central and Carlton London, even though none of these stations is broadcasting a PDC service. What they are doing is broadcasting a continuous PDC stream containing the timer mode flag. (This tells a PDC video to behave like a normal video and use its own clock to start/stop taping. See below.) Sometimes this is shown on the ITV teletext service p6AA. (Explanation below). This could be an encouraging sign - it means the companies involved have at least got the equipment necessary to broadcast a proper PDC service.

Some ITV companies explain their position on PDC on their teletext services on p695. I've written to the ITV companies who are not yet providing a full PDC service in the UK. Their replies are reproduced below.

It would appear that some ITV companies are waiting to get their systems in place for Digital TV before providing a PDC service (because it's very much easier that way). With Digital TV now up and running let's hope that's the end of the excuses. The bad news for viewers "served" by HTV is that PDC might never happen there, and they appear very reluctant for me to tell you that!.

Anglia

Funding Issues

Tim Dye, Technical Controller, Anglia Television wrote:

Anglia will not introduce a PDC service until we are certain it will be reliable. This is not likely to be the case until the introduction of Digital Terrestrial Television (which required PDC) towards the end of 1998.

In late February 1999, Anglia admitted they were running late with PDC. The Duty Office said:

We're now in the process of installing new automated equipment in Norwich and at our transmission centre in Southampton which should enable us to make this service available within the next few months. Anglia has been reluctant to provide a PDC facility until we could be absolutely sure of its reliability. It is a complicated and costly system to set up, involving a lot of extra technical facilities, and we are anxious to ensure the service is trouble-free.

At the end of 1999, I was told that all work on implementing a PDC service for Anglia and Meridian had been put on hold until at least February 2000 so that Year 2000 testing could take place.

In September 2000, the Duty Office admitted that no further progress had taken place because parent company, United News & Media, were not prepared to fund the introduction of a service that has no long term future. (There will be no PDC when analogue TV is eventually switched off.)

When Anglia and Meridian were taken over by Granada, it was hoped things might look up, since Granada had already introduced PDC in three of its other regions. The Duty Office told me they "very much hope that the issue will be looked at afresh, and that this time there could be a satisfactory outcome".

Unfortunately, when I checked again in November 2003, it appeared that Granada might be just as reluctant to splash out on PDC as the previous owners were. Debbie Humphreys of the Duty Office wrote:

The latest information we have from our parent company is that they too are not planning on investing in PDC as apparently when the analogue signal is finally laid to rest (estimates of when this will be vary) the technology will become obsolete.

Border

Full PDC Now

I originally wrote to Border Television in July 1997, but unfortunately, I never received a reply.

Then in 1998 a joint transmission system was set up in Leeds for Granada, Yorkshire, Tyne Tees and Border. This meant that Border had the facilities in place for a PDC system. Initially, however, they held back until it became clear to what extent their English and Scottish services would be split. It was promised that once they were confident they could deliver a PDC service that worked correctly and for the whole Border region, one would be implemented.

I checked again in November 2003. Chris Hearn, Head of Engineering at Granada, confirmed that Border has been transmitting PDC for some time.

Carlton London

No reply

I never received a reply to my original letter to Carlton London. I did get a response to an e-mail sent in November 2003, but it simply confirmed that at present there was no PDC service running. LWT's initial response is also applicable here, see below.

Carlton Central

"No Plans"

Originally, the Duty Officer wrote:

Central's PDC service does not as yet support transmission of data to viewers' VCRs in response to changes to programmes' scheduled time(s). At the moment Central does not have a full service - programmes can only be recorded using the time - it will not take into account programme overruns, etc. However, we are continuing to examine the issues associated with enhancing the PDC service.

At the moment we do not have any further information. May I suggest you refer to CENTEXT page 695.

I checked again in November 2003, when the Duty Office told me:

Unfortunately there are no plans for PDC on Central...

Channel

I e-mailed Channel Television, who provide an ITV service for the Channel Islands, in November 2003. I have not received a reply.

GMTV

I haven't written to GMTV, but they are included on this list because the company together with your regional ITV company, make up the Channel 3 service. In the mornings whilst they are broadcasting their programmes, GMTV "own" the local teletext service. The Duty Office at LWT have responded on behalf of GMTV (see below).

Grampian

Full PDC Now

Despite being owned by Scottish Television, who do run a full PDC service, Grampian weren't in any hurry to follow suit. John Robertson, Chief Engineer wrote:

Our present plans are to introduce this service in 1998 on the analogue service.

In Autumn of 1998 the main transmitter in our area - Durris - will start transmitting DTTV and this service will give a more comprehensive PDC listing.

I wrote again for an update in September of 2000. Bert Ovenstone, Head of Public Relations wrote:

We have been encountering software problems regarding the PDC system. Our engineering department tell me tests are now underway and they are hopeful of having the system up and running November/December.

I didn't check again until November 2003, when Mr Ovenstone replied:

I can inform you that PDC has been up and running on Grampian TV for some time.

Granada

Full PDC Now

Back in 1997, The Viewers Liaison Administrator wrote:

As you will probably have been informed from page 695 of Teletext, Granada provides level 2 of PDC and, at present, are not able to offer level 1. This is due to the different way the Channel 3 network operates. The requirement for level 1 PDC is one point transmission distribution as used by the BBC, Channel 4 and Channel 5.

In order to allow for a more regional based level of both programmes and commercials, Channel 3 distribution has to be from each television company direct to their allocated transmitters, rather than one point in London (or Cardiff, in the case of S4C).

As regional programmes vary in length from company to company (as do commercial breaks), it is not possible to generate PDC covering both network and regional opt-outs at present. When a compatible system is available, Granada and other ITV contractors will implement level 1 PDC.

Granada now share a joint transmission system with Yorkshire, Tyne Tees and Border. As a result of this, viewers in the Granada region have had a full PDC service since Mid-February 1999.

HTV

Wouldn't reply to me, but imply there's no demand for PDC which, they say, may yet prove obsolete.

The good folks at HTV don't want me to tell you about their plans for PDC. My letter to HTV in Bristol, dated 5th July, was never replied to. However, a viewer in their coverage area wrote to them independently to find out what their plans were, and got in touch with me to tell me what they said. When he asked HTV if I could quote what they had written, on this page, Lionel Jones, Chief Engineer replied:

Further to your enquiries on PDC, and your request for permission to post the information on a website:

We always try to provide bona fide viewers with as much information as possible when they write to us with queries and the response given to you accurately reflects the current position and the reasoning behind it.

However, I am not inclined to give permission for any straightforward answer to a viewer query to be published in another context as this would simply encourage a back-door approach from media writers. Any journalistic interest should be directed through the proper channels.

Mr Wiseman is undoubtedly aware that HTV do not support PDC at present and have no immediate intention to do so. This should be sufficient for his needs.

We will, of course, provide any update information via our own website in due course.

I will, of course, respect HTV's wishes and not quote their original response directly, but basically they say that the data required for a PDC wouldn't be accurate enough for a reliable service. A new transmission system is currently being introduced at Bristol and Cardiff (for Digital Terrestrial TV) which would give accurate data, but they imply there's no demand for PDC and say that PDC may yet prove to be obsolete.

If you live in the HTV West or HTV Wales area and believe that the company should be providing a PDC service, as the other four channels do, then I can only recommend you write and let them know.

Addresses:
HTV Limited, The Television Centre, Bath Road, BRISTOL. BS4 3HG
HTV Wales, The Television Centre, Culverhouse Cross, CARDIFF. CF5 6XJ

If they fob you off, then you could always complain to the ITC at: 33 Foley Street, LONDON. W1P 7LB

LWT (and Carlton London and GMTV)

Delays and now silence.

In 1997, the Viewer Liaison Officer wrote:

Currently PDC is broadcast to the London ITV region for LWT, Carlton and GMTV as "timer control" only and not to the optional full PDC specification. The full implementation makes provision for last minute schedule changes and late running. "Timer Control" PDC does however, provide a simple means of VCR programming and will be more current than published billings.

You can make use of our PDC service by selecting PDC on page 600 of ITV Teletext. This page is generated by our local teletext service.

Unfortunately it is not possible to insert a full PDC specification service into our present transmission infrastructure. It is planned to rebuild our transmission centre to provide full PDC specification, a better subtitle service and British Digital Broadcasting. It is hoped this will be up and running in June or July next year.

Unfortunately, the full PDC service didn't materialise. I wrote to LWT again in May 1999. The Viewer Liaison Officer replied:

I have contacted our chief Engineer who informs me that the PDC service for Carlton/LWT/GMTV is unlikely to be in full operation before the first quarter of 2000.

Thank-you for taking the time and trouble to write to us and I'm sorry if this news is disappointing.

I e-mailed LWT in November 2000, but haven't received a reply.

Meridian

As Anglia

The Duty Office Manager originally wrote:

I am afraid we cannot report any significant progress toward full PDC operation. A working party of all 15 ITV companies has been set up to look at the implementation of PDC. However, unlike the BBC or Channel 4, the ITV companies do not always run to the same schedule and integrating these such so that conflicts do not arise is causing some difficulties. Work has already been put out to a number of software houses for their solutions but we have no indication as to how far they have progressed to date and we would be surprised if the problems are resolved in a meaningful way within the next six months or so. A regular update on the PDC situation can be found on our engineering pages on teletext page 695.

When I contacted the Anglia Duty Office, in September 2000, they confirmed that any PDC service would be a joint operation between Anglia and Meridian. Although United News & Media were not prepared to make the money available to finally implement PDC, it was hoped new owners Granada might well take a different view. But this now seems unlikely. (See the Anglia entry above for more details.)

Scottish

Full PDC now

Scottish TV are one of the seven ITV companies that have acted independently from the ITV network and are already providing a full PDC service in their coverage areas (instead of excuses!).

Tyne Tees

Full PDC now

Tyne Tees, along with Yorkshire, have been providing viewers with a PDC service since December 1997. See Yorkshire's entry below for further details.

UTV

"It may be some time..."

Noel Henry, Community Officer wrote:

At this stage you are quite correct in that we do not have this facility. I have been informed by our engineers that because of the fragmented nature of delivering this service throughout Channel 3 that it may be some time before this will even happen.

I e-mailed UTV again in November 2003, but haven't received a reply.

Carlton West Country

Full PDC now

Westcountry TV, now owned by Carlton, was the first ITV company to introduce PDC for its viewers.

Yorkshire

Full PDC now

Francis Watson, Engineering Manager, Yorkshire Television, explained that their Teletext service started on 19th April 1995. This allowed viewers with StarText videos to program them from the listing pages (pp601-602).

Since then they began working on an interface to their transmission automation system to enable a full PDC service.

It is not an easy task, as we transmit 5 different regional variations (3 for Yorkshire, 2 for Tyne Tees), and we must ensure that the commands are sent to the correct place at the correct time.

The problems surrounding the project were soon solved and at 09:25 on Wednesday 17th December 1997 a full PDC service began on Yorkshire and Tyne Tees. The service is interrupted every day during the GMTV period (06:00 to 09:25).

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Channel 4

Channel 4's experiments with PDC began back in late 1991. The Channel is proud that it was not only the first broadcaster to transmit PDC in the UK, but that it also appears to have the most reliable service. This is attributed to its keeping the implementation as simple as possible.

4-Tel did finally get around to putting together a few words on C4's PDC service on teletext p390, but this was then removed. Later two more pages explaining PDC were added. An introductory explanation could be found on p393, with a more detailed explanation on p394. However, at the end of September 2003, Teletext Ltd took over the C4 ancillary text service contract and its revamped service no longer includes the pages on Engineering, widescreen and PDC.

Teletext Ltd have also completely removed the teletext service from the digital version of Channel 4 available to Sky viewers. This action will have also ended the accompanying PDC service.

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S4C

I e-mailed S4C back in 1997 about their plans for PDC and they told me:

S4C does not carry a PDC service and at present has no plans to implement one, although the matter is being kept under review, partly taking into consideration letters like this and partly the policies of other broadcasters.

I e-mailed them again in 1999 to see if their plans had changed. Gill Griffiths of the S4C Viewers' Hotline said:

I regret that S4C has no plans at present to introduce a PDC service.

>> If you'd like to see S4C broadcast a PDC service, you could e-mail them at hotline@s4c.co.uk or call them on 0870 600 4141 or write to them. The address is available at the S4C Web Site.

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Five

Channel 5 (now branded as Five) began broadcasting on 30th March 1997 with an experimental PDC service. Minor bugs were sorted out within a month or so of this date, and since then the Channel has regarded its system as fully operational.

Five's PDC signals are also carried on their cable and satellite transmissions.

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PDC and VPS on Cable/Satellite/Digital TV

Some satellite stations are sending out PDC data. So how is it possible to use PDC on satellite and cable? There are two difficulties: first a PDC video needs to change channel to look for the PILs - most videos cannot change the channel number of the satellite/cable receiver. Second, a channel numbering agreement would be needed. However, at least two manufacturers have overcome the problems of using PDC on satellite.

So it is possible to use PDC on satellite and cable and I have the e-mails to prove it.

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PDC via Satellite

Hywel Williams used to receive Channel 5 from his analogue satellite system: the terrestrial signal is non-existent.

... I tuned in C5 on my video recorder and set it up to record a programme with the PDC flag turned on. Sure enough, instead of using the timer, it was activated by the PDC stream...

As using a UHF channel for the satellite would mean that I'd only get a mono sound channel I decided to see if I could get PDC to work on the AUX input from the SCART. Again I programmed the VCR to record a programme from C5 but this time told it to record it from channel AV1. Since this isn't recognized by the VCR as C5 in the initial autotune I set the PDC flag on manually. Once again, the VCR used the PDC stream to initiate recording, proving that PDC can be used to start up recordings even on the SCART input!

Unfortunately my Panasonic NVH-S900 doesn't have a satellite control facility so I have to program the satellite receiver separately. I had a quick glance in Sevenoaks HiFi recently - it looks like the next generation of Panasonics will have this feature which could make PDC on satellite more interesting. I wonder if it'll flick between 2 satellite channels looking at their PDC codes ? This would make watching the satellite a little difficult before the show starts...

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PDC via Cable

Philip M Reynolds has been experimenting with PDC on BBC2 and Channel 5 through his (analogue) Diamond Cable box using a Mitsubishi HS-541V video.

... The video has an infra-red output, which controls the [cable] box. When using PDC on cable, you see the box hop channels as necessary. It works as well as it does in the ordinary way, although the video's infra red output is on the right, the cable box's sensor on the left, so I've had to perch the box on a spare video tape.

My experiment with BBC2 and Channel 5 ... completed OK.

It seems that the video does not understand SAT1's VPS signals. I have been unable to find out about PDC on other channels. Sky say they have no plans to use it.

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PDC and Digital TV

According to BBC Reception Advice, the PDC feature seen in many modern video recorders will not function on digital television. However, according to the ITC it may be possible that the EPGs (Electronic Programme Guides) for digital will feature a "reminder" service to tell you a programme is about to start as well as some way of automatically video-taping programmes you select.

Contrary to what the BBC says, Five (but sadly no longer Channel 4) are broadcasting a teletext stream on digital satellite that includes a working PDC service. Viewers with SkyDigital boxes may therefore be able to use PDC on the digital version of Five.

When Digital Terrestrial launched, the equipment wasn't designed to decode traditional teletext services. The idea was to replace teletext with enhanced digital text services. Hence if you are recording from an iDTV or ONdigital/FreeView set-top box, you won't be able to use PDC.

With digital cable, the availability of PDC will depend on whether the channel carries the full teletext stream (as with SkyDigital).

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VPS via Astra

Many of the foreign channels on the Astra analogue satellites support VPS. Viewers in the UK with non-digital satellite receiving equipment and videos that support VPS can therefore use this system to tape from these channels.

Darren Nadin reports that his Ferguson FV 91 LV identifies the following Astra stations as supporting VPS. (They are listed with the Channel IDs which show up on the front panel display of the video.)

3SAT3 Sat
EUROEurosport
KAB_Kabel 1
_N3_N3
PRO7Pro 7
RTL_RTL
RTL2RTL2
SAT1Sat 1
VOX_Vox

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PDC in Europe

PDC is a European standard and has been available in mainland Europe for some time, where it began life as VPS.

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Austria

Austria use a simpler variant of PDC called VPS - Video Programming System.

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Belgium

Thanks to Robert Cuijpers and Philippe Vijghen for the following information.

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Czech Republic

Thanks to Jan Sritter for the following information.

In the Czech Republic, there are four public TV broadcasters.

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Denmark

Thanks to Martin Rasborg for the following information.

In Denmark there are two national broadcasters, both are transmitting PDC information.

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Finland

Thanks to Camillo Särs for the following information.

The Finnish public broadcasting company YLE has two channels, TV1 and TV2, both of which are broadcasting a PDC service.

YLE state on their web site that PDC transmissions began in 1994. They constructed their PDC hardware themselves, based on the Domestic Video Programme Delivery Control System (PDC) EBU SPB 459 Rev. 2 February 1992 specifications.

Normal PDC transmissions are partially automated; live broadcast are handled manually. Camillo's impression is that PDC signals are usually reliable. "Occasionally when programs are delayed, the start time is not reset, but the end time practically always is. This I have seen once, i.e. the beginning of the recording was from the previous program, but the end was correct."

Additionally, YLE says that the start signal is transmitted 30 s before the actual beginning and the stop signal 10-15 s after the actual end. Channel hopping is yet unimplemented and program classes (PTY - see below) are not transmitted except for the news and sports news.

>> YLE's web site is mostly in Finnish, but there are some English pages. The site includes a PDC info page, again in Finnish only.

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France

France 5 claims it and Arte are the only French broadcasters using Le PDC.

>> More details about the service are available at France 5's Web Site, but only in French.

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Germany

Germany use a variant of PDC called VPS - Video Programming System. It is also in use on Germany's Astra satellite channels. (See above for a list.)

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Netherlands

Thanks to Peter Broekhuizen for the following information.

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Switzerland

Thanks to Pete Ford and Svend Waldorff for the following information.

In Switzerland, videos are equipped with a simpler variant of PDC called VPS - Video Programming System.

Switzerland currently has 6 national TV channels: TSI1 and TSI2 (Italian), TSR1 and TSR2 (French), SF-DRS1 and SF-DRS2 (German). All of these use VPS. Two German stations, TV3 and Tele24, are also available, but these do not provide a VPS service.

Just about every house has cable as standard, because the mountains make normal aerials useless. The cables carry over 30 different stations.

ORF1 and ORF2 (Austrian channels) and 3:sat (German) use VPS, as do Sat1 (German) and RTL2 (Luxembourg). Arte (French/German) uses VPS as well as PDC.

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How can I test whether a PDC service is being broadcast?

Given that stations cause the PDC indicator to light even when there's no PDC service in operation, how can you tell the difference? Here's an idea that might work - tape a programme, but set the turn off time to be only five minutes after the turn on time. If the station is broadcasting PDC, then you should get the whole programme, otherwise you only get the first five minutes.

Alternatively, if you have a video which can tape the current programme using PDC (this function may be described as "record to (next) stop (code)") then try this out and see the video begins recording.

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Miscellaneous questions

Does PDC work with TiVo / Sky+ / DVD Recorders ?

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Does PDC work with VideoPlus+ / ShowView ?

Most new videos on the market, especially those with PDC, also have VideoPlus+ (known as ShowView in Europe and as VCRPlus+ in the USA). The two systems can be used together.

If you use the Radio Times to set your video, you will occasionally find that the odd programme will have a different start time for use by PDC video owners. This start time will also have its own VideoPlus+ number which you should use if you are taping using the PDC facility.

Gemstar have a VideoPlus+ help-line which customers can call if they have any problems with the system, and lately they have found an increasing number of calls are about PDC. The company has been working closely with the broadcasters in order to try and alleviate the confusion and problems to do with PDC.

>> Further details on VideoPlus+ and PDC are available at Gemstar's web site.

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What is StarText? What is VPT?

StarText is a name for the system of programming a video recorder by selecting the programme from a teletext listing page. A StarText/PDC video looks up the PIL codes from the lines hidden below the Fastext line in the teletext TV listings pages.

However, it is also possible to buy videos that you can program from teletext pages, but which do not have PDC capability; they do not look up the PIL from the page. These videos also use hidden codes in the teletext listings pages on ITV/C4. These codes can be seen if you press REVEAL on your remote control handset.

Both systems (with and without PDC) may be known as VPT (Video Programming by Teletext).

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Why does the PDC code work on original start times?

Originally, the PDC specification allowed for a unique code for each programme. This code did not rely upon knowing the original scheduled start time. However to use this system, TV magazines and newspapers would have to have published this PDC code alongside the programmes and it was thought unlikely that they would be willing to do this since they were already publishing VideoPlus+ codes. Also, the system was delayed enough as it was, again VideoPlus+ was already available and so for PDC to stand a chance of becoming established, video machine manufacturers had to start making PDC-enabled machines as soon as possible.

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How can we guarantee to know the correct original start times?

When programming manually or by VideoPlus+, the best place to get the start times is weekly TV listings magazines (or your free local newspaper). However, it's possible that last-minute changes have been included in these publications too, after the PDC code has already been decided. The Radio Times states that when this happens they will amend the programme details with a note for PDC users to show the original start time and its corresponding VideoPlus+ number. Radio Times is the only publication that has undertaken to do this.

Teletext listings are the worst place to get the start times from, since they are likely to show last minute schedule changes (and hence not the original start times). The PDC spec. recommends that when this happens broadcasters should show PDC times on teletext listings, but none of them do. C4 get around this problem by broadcasting two PDC streams - one with the original start time in and one with the start time shown on the listings page. It is the only broadcaster to do this, to my knowledge.

With a StarText/PDC video, you don't have to worry about knowing the correct original start times, simply program the video using the teletext pages.

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What if you want to tape two programmes on different channels?

The video will hop between different channels as necessary checking for the PDC signals. On some videos there's a visual indication that this is happening.

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When does the video start looking out for the broadcast PDC code?

See answer below.

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What if two programmes are later re-scheduled to overlap?

If you're taping two 60-minute programmes, show A at 21:00 on BBC2 and show B at 22:00 on C4, and then the C4 show is re-scheduled to begin earlier at 21:30, say, what happens?

Priority is given to the show already taping. So you'll get all of show A and after that the video will start looking for the PDC code for show B and start taping that. You will miss the first half hour.

But what happens if C4 re-schedule show B to start at exactly the same time as show A?

This is undetermined. It may depend on the video manufacturer's specification. What's likely to happen is that whichever show has its PDC code broadcast first gets taped. If both codes are transmitted simultaneously then the show will be recorded from whichever channel the video was looking at during its channel-hopping search for the PDC codes.

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What are the limits of PDC in terms of a re-scheduled programme?

The PDC specification states:

So if a programme is scheduled for 21:00, then the PDC video begins looking for the PIL at midnight, twenty-one hours before the advertised start time. And if a programme is scheduled for 09:00, the video should still be looking until 04:00 the next morning.

However, PDC does allow for re-programming of your video, so that if it is waiting for a PDC code to be transmitted but the programme is rescheduled outside of the above limits (or indeed the programme is moved to another channel), then the video can switch to using a new PIL (containing revised date/time/channel information). This is done using what's called the LUF (Label Update Flag).

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Do I need a teletext TV for PDC to work?

No! Even if you have a StarText/PDC video which allows programming directly from the teletext listings pages, the teletext decoding equipment is already in your video.

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Will a PDC video miss out commercial breaks?

The answer to this is no it won't, not at the moment, and there are no plans for it to do so. However, this isn't because it's technically impossible (in fact there's a special code with which recording can be paused). To implement the skipping of commercials, (a) would involve more work by the broadcaster sending out the pause code at the right time and (b) might offend the advertisers.

It's a pity because PDC is an ideal system for skipping ad breaks. The Japanese are already looking at ways of building videos that will cut out the commercials in more complicated ways.

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Can I check what PDC codes are being broadcast?

To find out what all the numbers on these status pages mean, see below.

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Technical Questions

What exactly is a PDC code/signal?

For the real answer to this question, you need to read the PDC specification (and be able to understand it). It's over 80 pages long. (See below for how to get hold of a free copy.) But for a feel of what the PDC code is, in layman's terms, read on...

You can now see for yourself what a PDC signal consists of thanks to Robin O'Leary who has a computer connected to a teletext decoder connected via radio modem to the Internet. He feeds the PDC information (decoding it on the way) to a web page.

You will see on Robin's page that the PDC signal for controlling video recorders comprises the Programme Ident Label (as discussed above) plus some other data.

In most cases the date and start time obviously correspond to the programme currently being broadcast. This tells the video to tape the programme for as long as that code is transmitted. However, there are some PDC codes which have an impossible date of 00/15 and a time of, for example, 31:63. These codes are special PDC modes. Valid modes are stop, timer pause and continue.

FlagTimeDescription
Timer31:63 Some ITV regions transmit the timer mode flag constantly. Five also use it during their hourly news bulletins (because they don't have a scheduled time, as such). This flag forces the video to revert to its internal clock for recording.
Stop30:63 The BBC (but not, apparently, C4) broadcasts the stop code (technically known as the RI/T or record inhibit/terminate code) for about 8 seconds at the end of a programme.
Pause29:63 The pause (or interrupt) state tells the video to stop taping temporarily. If they wanted to, the commercial channels could use this flag to cut out the commercial breaks from a recording.
Continue28:63 This is used to tell the video to continue taping following a pause. However, C4 use this flag between programmes instead of the stop flag.

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What do the numbers mean on teletext p5AA/p6AA ?

Thanks to Robin O'Leary for this information.

As explained earlier, you can monitor the four PDC streams currently being broadcast on ITV1 and Five by turning to the clock cracker page of the ancillary teletext service (p699 on ITV1 or p598 on Five) and then pressing the RED fastext button. Sadly Channel 4 stopped broadcasting its hidden PDC page at the end of September 2003.

Here are a few examples (which I've colour-coded for ease of reference):

   from Anglia: 0 1 2C 1E 00 00/15 31:63 1
from Channel 4: 0 1 2C 11 83 02/09 19:00 1
     from Five: 0 3 2C 02 00 17/11 19:00 1
2C, which is hexadecimal for 44, is the UK country code (co-incidentally the UK's national telephone code).

The green number identifies the television channel. Each channel in the EBU has one or more numbers assigned to it. Anglia and LWT are using the code for the ITV Network, despite having codes of their own.

The light blue number is the Programme Type Indicator (PTY), which is explained in the next question.

The blue numbers show either the "advertised" start time (i.e. that used in the PIL), as shown in the C4 and Five examples, or they represent a special flag, as in the Anglia example. The C4 example is for Channel Four News starting at 19:00 on September 2nd. The code in the Anglia example is listed with the other codes in a table above.

Usually of the 4 streams shown on these pages, only the first will have any meaningful (i.e. non-zero) data. This is because most commercial broadcasters use only a single stream. However, sometimes Channel 4's page showed two streams in use, each with a different start time. This is a cunning technique that allows viewers to program the video using either the original start time (e.g. from Radio Times) or the latest scheduled time, if this differs, as shown on the teletext listings pages.

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What else is in the PDC data? What is the PTY ?

Thanks to Robin O'Leary for this information.

There is another code broadcast in the PDC data called the Programme Type Indicator or PTY. This can indicate the intended audience of a programme or the type of programme. Broadcasters can also use it to identify a particular series.

The PTY code allows a sort of "standing order" to record. So you could say to your VCR "record any science programmes", or, on C4, "record the Brookside Omnibus". This feature is supported by the Akai VS-G2200 and so, for example, if you use the video's StarText feature (i.e. you program directly from the teletext page) to tape Brookside, the video gives you the extra option of "Repeat recording (y/n)".

There is also an interesting PTY code called Alert. This is supposed to be recorded by any PDC VCR that's in standby mode! The intended use is for national emergencies.

>> The list of PTY codes and their meaning is given at Robin O'Leary's PDC Live web site.

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PTY on Scottish Television

Thanks to Jim Main for the following information.

Scottish Television has been using PTY codes since early 1996 and more recently has been using a number of series codes.

Anything over 80 (hex) is defined as a series code, tied up to the network identifier so that different stations can use the same codes for different programmes (as you will see).

Scottish use the following codes.

PTY (hex)Description
81Coronation Street (First showing)
82Coronation Street (late night repeat)
83Emmerdale

There are more codes than this, but they are only applicable to Scottish TV.

Scottish also allocate guest series codes to mini-series, for example a three-episode run of Dr. Finlay, so that viewers can catch all episodes without re-programming. In the PDC spec (300231), it says that you can re-allocate codes a month after the programme finishes - so these codes can be re-used the programme run has finished.

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PTY on Channel 4

Channel 4 have also used series codes 81, 82 and 83, as follows.

PTY (hex)Description
81Brookside (during the week)
82Brookside Omnibus (weekends)
83Channel 4 News (every evening)

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Where exactly is the PDC signal broadcast?

For this you need to understand how teletext works...

Thanks to Steve Hosgood and Steve Gutteridge for the following info.

If you adjust the vertical hold on a TV picture you'll see a black band with rows of twinkling dots. The black band is called the Vertical Blanking Interval (VBI) and the rows of dots are the teletext scan lines where the teletext data is transmitted.

Each teletext page consists of a number of rows or lines of text/graphics. Each row is transmitted in a separate packet. Additionally, each set of pages belong to a magazine. For example, pp100-199 belong to magazine 1. So the 3-digit "page number" you dial into your Teletext decoder is in fact a one-digit "magazine number" followed by a two-digit "page number". The distinction is not relevant to the end-user, but is more important to the information providers as it dictates how exactly the information may be interleaved during transmission.

Basically every Teletext scan line carries a packet. Typically the data in a packet (40 bytes) consists of all the information for one line of one page of one of the magazines being transmitted. To save space in the transmission format, the whole addressing information (i.e. magazine, page and line number) isn't sent on all packets. Only packet zero (the title line at the top of all pages) carries it all. Subsequent lines only carry the magazine number and packet number (usually written M/PP in discussions).

Packet 0
(as discussed) carries the page-number, broadcaster's ID and the date in a fixed format. It also carries some flag information relevant just to that page itself.

Packets 1 - 28
carry info which are part of the page identified by the most recent packet 0 of the same magazine. These packets may appear in any order, and may be interleaved with packets for pages in different magazines. A page is considered complete when the next packet 0 appears for that magazine.

Packets 1 - 24 are the lines of on-screen text (including the Fastext labels in Packet 24). Blank lines on-screen are not transmitted in order to save bandwidth. Packet 25 contains text to be used in place of the normal header (e.g. on ITV p888, "ITV SUBTITLES"). Packet 26 is where the PILs are transmitted. Packet 27 contains, in coded form for data integrity, the page numbers to which the Fastext labels refer. Packet 28 carries other non-visible information for a page, e.g. which language (i.e. character set) to use.

Packets 29, 30 and 31
are special. They may appear interleaved with the other packets as and when required.

Packet 29 carries information relevant to its magazine as a whole. Packets 30 and 31 carry information relevant to the TV service as a whole (for instance, PDC) and their magazine numbers are thus not really relevant. At the moment though they are always transmitted with their magazine number set to '8'.

So the answer to the question is that the PDC data is transmitted on Teletext in Magazine 8, Packet 30.

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More about packet 30

Thanks to Antony Purvis for the following info.

When you change channels on some teletext TVs, the station name appears on screen. This name is also broadcast in packet 8/30. It contains the channel's name (in text) plus a few other control codes like the channel's EBU identifier, what time zone the teletext service runs on, and which page number a teletext set should select as the "front page" (400 on Channel 4, 100 on ITV, for example.)

The jargon for the TV station name is Short Programme Label (SPL) and its full packet address is 8/30/1 - see next question.

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How does one packet carry so much data?

Thanks to Steve Gutteridge for the following info.

Some teletext packets include a designation code, which is used to distinguish two or more packets with the same packet number but carrying different information.

This designation code effectively then produces two different types of packet 8/30, referred to as format one and format two. Packet 8/30 format one is the normal Television Service Data Packet, also given other names, that carries the time, date and other bits. Packet 8/30 format two is a packet containing PDC information. Each of the 8/30 packets is transmitted once a second. PDC has the capability of flagging up to four programmes at once. You would use two if you have an overlap, but you might also have a "programme within a programme" where you nest two separate PDC codes. In that case, there might be up to 5 packet 8/30's transmitted per second - one format 1 and up to 4 format 2's. Again, an over-simplification, but you get the idea.

Similarly, packet 26 uses designation codes - it takes about three packets to store the PILs on each of the teletext TV listings pages.

So the even fuller (i.e. full of jargon!) answer to the question of where exactly the PDC signal is transmitted is: the PDC signals are transmitted in Broadcast Data Service Packet (BDSP) 8/30/2 in accordance with CCIR teletext system B.

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So where is VPS broadcast?

This information was gleamed from the web pages of Siemens Semiconductor Group and of Philips Semiconductors.

For the VPS system used in some other European countries, the PDC data is transmitted on a dedicated line of the vertical blanking interval, line 16. The VPS broadcast system is technically known as EBU's PDC method A, whereas the PDC system described above is known as method B.

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Problems with some makes of video

Below I've listed some problems that owners of some PDC videos have reported. If you have a PDC video, you could contribute by experimenting with your machine to see if the same problems are found. This may help potential buyers weed out the not-so well behaved machines.

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Taping continues after the programme has finished

Some PDC videos don't stop taping until a short while after a programme has finished. The BBC claim that they send out the stop signal promptly, so why is it some videos keep going?

It may be that some video manufacturers have caused this because of Channel Four's implementation of PDC. Reportedly, C4 do not send a stop signal at the end of each programme. So in order to make sure that a programme has really finished and that the PDC signal hasn't simply been lost temporarily, the video keeps going for 30 seconds after the signal is lost. Since C4 were the first channel to broadcast PDC, some video manufacturers may have built their machines to work with C4 and assumed that other channels would implement PDC in the same way.

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Taping consecutive programmes

To illustrate this topic, we will take the example of BBC2 broadcasting Star Trek followed by Buck Rogers on Wednesdays. (Even if they don't any more!) Some PDC videos (e.g. Toshiba V854B, Sony SLV-E90), when programmed to record both programmes, stop taping for between 7 to 20 seconds during the opening titles of Buck Rogers.

Steve Gutteridge, from BBC Reception Advice, thinks that this problem is another example of videos not stopping promptly after the PDC code has finished. Suppose the video recorder waits for 30 seconds after the PDC code for Star Trek has finished before it actually stops taping and that the PDC stop code is sent only 20 seconds before the Buck Rogers begins. This means that the video stops 10 seconds into Buck Rogers.

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Timer Memory not clearing

Some videos retain their programs in memory for days after a programme has been successfully videoed. The BBC have put this down to their use of overlapping codes.

There can be up to four active PDC codes transmitted at once. This might be useful, say, as the BBC1 One O'Clock News is about to finish when its PDC code is still active and then the PDC code for the Weather becomes active and then so does the PDC code for Neighbours following the Weather.

BBC2 have been overlapping codes for their programmes. In our example where you have Star Trek followed by Buck Rogers, the start code for Buck Rogers is transmitted before the stop code for Star Trek.

Presumably this is because BBC programmes are closer together and the worry is that you have to give the video enough time to be running so that it doesn't miss any of the programme. C4, reportedly, don't overlap their codes. But then they have commercials and hence more time between programmes.

However, timer memory problems have been reported when taping from C4, too.

Overlapping codes might also contribute to the problem with taping consecutive programmes. After all, if the PDC stop code for Star Trek came 30 seconds or more before the PDC code for Buck Rogers (i.e. there was no longer an overlap) the gap in the recording experienced by some PDC video owners might be moved to between the programmes. This may be impossible to do with programmes that are broadcast too closely together, however.

Akai have also supplied one of its customers with another explanation for programmes remaining in the video's time memory. Peter Raggett noticed his Akai VS-G2200 was retaining programmes in memory for 24 hours. Akai told him that this was in case "the programme came back". For example, ITV often used to show a film broken up in the middle by News at Ten, and retaining the memory enabled the video to tape the film and miss out the news.

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Summary of Videos

Below I've summarised the makes and models I've been told about and whether they're badly behaved or not. Remember, sometimes problems experienced are the fault of the broadcasters and not the video. Also some manufacturers may make improvements in a later revision of a particular model.

Akai

VS - G2200

Has PDC/StarText. Supports the PTY indicator, so you could ask it to record a week's worth of Brookside in one go, for example. Cleverly allows the recording of teletext subtitles by superimposing them on the picture and then recording the composite picture on the tape. Supports record-to-end of programme. Programmes can remain in timer memory for 24 hours. Misses out the beginning of subsequent programmes when taping consecutive shows. Tim Hewett reports that his machine (and its predecessor the AKAI xxx-1100) was taken back to the shop several times in an attempt to fix a PDC gremlin on channel 4 - when a C4 program ran late, the VCR would start recording for about 30 seconds, then stop for a further 30 seconds before repeating the cycle. The VS-G2200 does this too, but records much shorter bursts, and seems to rewind back over the recording when it stops again.

Daewoo

DV-F 932 P

Simeon Tankard recently bought this video as a second video. Its a budget model costing only £230, but boasts NICAM/Hi-Fi sound and VideoPlus+ as well as PDC. His machine works perfectly on C4 and C5, but not so well on BBC2. What happens is that shortly after starting to tape a show, the Daewoo switches back to stand-by mode, and then starts again and then stops. "Usually at the third attempt, about 30 seconds into the actual programme the video will stay recording. At the end of the programme I have seen the video stop, then start again briefly before stopping again." Simeon knows its not his TV reception at fault, because he's set up concurrent tests with his first PDC video (Panasonic NV-HD605), which tapes the same shows fine from BBC2. BBC Engineering Information (now BBC Reception Advice) suggested he contacted the dealer/manufacturer.
K 985 P Farhan Masani bought this budget NICAM Stereo deck with PDC for around £155. He found PDC works well on all 5 channels. You have to turn on PDC manually for each individual timer recording. One odd feature he found was that the timer information is retained in memory until 4am the next day. This was not a major problem though, you can easily delete the entry before then if you need to.

The machine appears to wait for approx. 30 seconds after the PDC code for the first programme has disappeared before it stops taping. This means that you usually miss the first few seconds of the second programme if you are recording consecutive programmes. Interestingly, this only happens on ITV (Yorkshire in this case), Channel 4 and Five. When taping consecutive shows from BBC One or Two the recordings are fine. This may be down to the lack of a STOP code on the commercial channels.

Ferguson

FV 91 LV

Darren Nadin reports that this video supports both PDC and VPS, and works perfectly on BBC2, C4 and C5, as well as on some European satellite channels. It has built-in functions to record to the end of the current programme, and also to record the next programme. It can control satellite/cable systems via infra red. It also automatically names the foreign channels from the ASTRA satellite that support VPS on the front panel of the video, giving the channel a 4-character name, e.g. RTL2 and _N3_. (Although these names are not displayed when the satellite receiver is connected via SCART, when SA01-SA99 are displayed.) Darren is especially pleased with his purchase since Norweb sold it to him for the bargain price of £170. (It was the last one in stock.)
FV 105 LV This is a more advanced version of the FV 91 LV above. It supports NICAM and costs about £350. What Video & TV gave it 9 out of 10.

Goodmans

SD 1800 PDC

Peter Ford bought this budget model for a mere £140. To use PDC you have to explicitly switch it on (it's not on by default).

Grundig

GV250

Has PDC/StarText, and a fascinating "Archiv" facility, which maintains a catalogue of the contents of 999 videotapes: when programming using StarText, the programme's title is automatically placed into the catalogue against the tape currently in the machine. The VCR is able to control a compatible satellite receiver (e.g. Grundig STR1, Pace PRD900) over a special line in the VCR SCART. Thus it can be programmed to record any of channels S01 - S99 as well as the terrestrial channels. PDC works perfectly on this recorder on the BBC2 and C4 transmissions. So where can you get your hands on such a marvellous machine? You can't! They don't make them any more. (Sorry!)

Tony Lamb also has this model. He says it's wonderful, working perfectly on C4 and even on C5 where the picture isn't as good. "... but BBC2 is a nightmare. It can kick in okay every time but it never knows when to stop. you could record Star Trek and get BBC2 for 4 hours ignoring any later recording or it could start for 10 minutes then just stop. BBC blame Grundig, Toshiba etc who use 1 system where JVC use another." He's understandably miffed that the BBC decided to implement a service that doesn't appear compatible with his machine, when the C4 system has been working perfectly since he bought the machine, about six years ago.

Mitsubishi

HS - 551V
(Nicam)

HS - 541V
(Mono)

This video puts a gap in between consecutive programmes on C4, usually resulting in missing the opening of the second programme. The video defaults to PDC off - you have to manually amend a 't' to 'p' on the onscreen display if you decide to use PDC. Occasionally it retains program information in memory.

Philip M Reynolds reports that his video is at its worst when changing from C4 to BBC2. He also reports that he has successfully used his HS-541V to control and record from cable television. (Read his report above.)

Panasonic

A common feature of earlier Panasonic PDC videos (not the NV-HD series) is their ability to retain the timer memory for days.
NV-HD100 This machine does not feature PDC as standard, but one owner was pleased to find that for £80 it could be upgraded. John Hewett's machine now retains the timer settings in memory when PDC is used, which is annoying because until they are deleted using the remote control, you cannot use the machine to play or record or anything else! Panasonic told Mr Hewett that the machine would delete the settings itself the following day.
NV-HD630 Farshan Masani also has one of these machines. Like his Daewoo, he has to turn PDC on manually for each individual recording - by default it is set to off. This model features NICAM Stereo plus an interesting search facility that allows the user to see what timer recordings have been made on the tape currently in the machine, providing that the tape hasn't been removed since the timer recordings have been made. It doesn't have any problem with consecutive programmes and it doesn't retain the timer settings in memory.
NV-HD680 This is my own machine. A Nicam hi-fi model with VideoPlus+ and PDC, it also has the ability to record teletext subtitles. My favourite feature is the tape library - it stores the recordings you make for each tape, retrieving the programme names where possible from the teletext 'now and next' pages. It has auto-setup and when scanning for new channels decides whether PDC is supported or not. When you come to record, PDC is set to OFF for channels that support the feature. You have to manually set it to ON. This model doesn't have any problem with consecutive programmes and it doesn't retain the timer settings in memory (unless the recording was interrupted or was not made). Cost around £320. Now superseded by models with an even better tape library.

Philips

VR 4557/05

Stephen Livingston is a primary school teacher and thus records a lot of programmes on Channel 4 and BBC2. His VR 4557 fails to tape Channel 4 programmes, but works fine for BBC2. The Channel 4 pictures are coming from the Divis transmitter in Northern Ireland. The machine will not record at the beginning of a programme and has frequently taped the last 5 minutes of 15 minute broadcasts. Stephen phoned C4 who were unable to help.
VR 757 One owner, Peter Chidzey, has not been able to use the PDC feature at all. The machine switches itself off on both BBC2 and Channel 4 within 5 or 20 mins of it coming on, so a complete programme is never properly recorded. The machine was replaced under guarantee, but this did not solve the problem. Philips have since offered Mr Chidzey a full refund. Channel 4 (finally) said that they thought there must be a software problem with the Philips machine and the only advice they could offer was to buy a different make of VCR. Which? magazine had tested this model and they did not have a problem with the PDC feature.

Terry Jones described similar problems with his 757. He bought his machine in August 1996 and found that, just like Peter's video, it stopped 20-30 minutes into PDC recordings. It also seemed to reset itself after some recordings, displaying "E15-234" (possibly some kind of error code) before it died, clearing all remaining timer recordings. The recorder went back for repair, but it made no difference. Eventually, it was swapped by the retailer for the new 768...

VR 768 VHS deck with PDC/StarText. As stated above, Terry Jones was given a VR 768 in exchange for his VR 757 which malfunctioned when using PDC. Terry says the 768 seems a bit more up-market in design to the VR757. More importantly, the PDC function works fine on both BBC2 and Channel 4.

"The handset is much smaller/neater and has no dodgy/easy to break flap to hide buttons from the easily confused! Picture and sound quality are excellent as is NTSC playback (but for a machine that lists at £499 it should be!)" The StarText feature is clever but does require a lot of button presses to work it (my 'other half' says its easier to pick up the radio times and type in the VideoPlus+ code). If I pick Brookside or C4 News [which have PTY codes] I get the option of 'One Episode' or 'Entire Series'."

VR 838 VHS deck with PDC/StarText.
VR 948 Another Philips video owner, Ian May, says he has the same problems as reported above for the Philips 757, but only on BBC2: he's had no trouble with recording from C4. This video has StarText and a teletext subtitle-recording facility. It also has FastText and the StarText supports the PTY indicator, so you could ask it to record a week's worth of Brookside in one go, for example. This is a SuperVHS machine, RRP £800. Tim Hewett recommends if you want one, you could haggle your way down to about £600!

Sony

SLV - E90
SLV - 700

When programmed to record consecutive programmes on BBC2, this video stops taping for between 7 to 20 seconds during the opening titles of the second programme. Other videos do the same. Takes about 30 seconds to stop taping after the STOP code is broadcast, which means if the STOP code itself is late, you could have a few ads and trailers and if you want to tape a show on another channel, you might miss the beginning.
SLV - E710 Tim Adye had such a bad time with PDC he ended up taking back two different videos to the shop in the same week! One of them was the Sony SLV-E710 (UX) (which has possibly now been superseded by the E810). On this video, PDC is off by default. To turn PDC on, or to change any programme settings apart from SP/LP, after programming with VideoPlus+ is ridiculously cumbersome. Because of the use of one key to provide many functions, it's also too easy to change something you didn't want to change, such as the programme time!
SVL - E810 When programming the video defaults to PDC off. Sony say this is because people who owned the previous model, which had PDC on by default kept ringing up to complain that they'd missed a few minutes of a programme on, say BBC1. So you have to enter the VideoPlus+ code, then manually amend the program to turn PDC on.
SVL - F900 This Nicam model features an amazing tape library system called "SmartFile". The video stores the programme title of everything it tapes (found on the teletext listings pages) on a microchip hidden in special tape labels. Then when you want to find out what's on the tape simply wave it in front of the machine. You can also highlight the programme you want to watch on the tape and the video will fast forward or rewind to it. The machine features VPS as well as PDC. The only problem seems to be with the automatic clock correction feature. This needs to be switched off or else it screws things up big time. Sony are aware of this.

Toshiba

V854B
V856B

Same problem with consecutive programmes as the Sony SLV-E90. Also retains the timer memory. Plus, earlier models (if not all!) have the problem that when you tape a programme using PDC and then the next show without using PDC, the second show does not get taped at all.
V855B Retains the timer memory for BBC2 but not apparently for C4. It also has the ability to send infra-red control signals to a satellite/cable decoder.

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I want to know more!

Unfortunately, details on PDC, aside from the really simple stuff and the really complex stuff, are not easily available, which is why I put this page together. The ITV companies suggest you contact your local TV/video retailer :-)

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Acknowledgements

I'm extremely grateful to those who have taken the trouble to e-mail me, especially Darren Meldrum, Hywel Williams, Ian Collier, Mike Henry, The Watcher, Marcus Bainbridge, Roger Allen, Phil George, Peter Raggett, Rod Begbie, Tim Steele, Brian {Hamilton Kelly}, THE Adrian, Peter Chidzey, Ian May, Tim Hewett, Robert Cuijpers, Peter Broekhuizen, Hendri Hondorp, Camillo Särs, James R Grinter, Patrick Limbird, Mike Ives, Philip M Reynolds, Terry Jones, Stephen Livingston, Tim Adye, Martin Rasborg, Tony Lamb, Darren Nadin, Pete Ford, Simeon Tankard, Farshan Masani, John Hewett, Philippe Vijghen, Svend Waldorff; to those who have patiently explained the technical stuff: Steve Hosgood, Ant Purvis, Robin O'Leary and Jim Main; to Leon de Beer, Technical Director, Gemstar Europe; to Francis Watson, Engineering Manager, Yorkshire Television; to Steve Gutteridge, Roderick Duncan and the team at BBC Reception Advice and to Aiden Stowe, deputy editor of Ceefax. Many thanks to you all!

If there are any errors in the text, or you have any other comments, (especially if you want to report a badly/otherwise behaved PDC video) then please feel free to e-mail me.

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Other TV/Video Technology Links
>> To enhance your knowledge of PDC further, you cannot afford to miss Robin O'Leary's PDC Live site.

>> VideoPlus+ is easy to decode, but harder to encode. Ian Collier has a PlusCode decoder program for the Sinclair ZX Spectrum, but which could be easily adapted for other computers.

>> Steve Hosgood has an interesting web page on VideoPlus+ which includes a DOS codec and a discussion on how PlusCodes are calculated for the different systems in the US, UK and Europe. Steve also has technical details of PALplus, the system once used by C4 and other European broadcasters to transmit wide screen (16:9) television pictures, and Nicam the digital stereo system for analogue television.

         
  PDC on Right to Reply  

In October 1997, I appeared on C4's Right to Reply to explain what PDC is. I got to ask C4's Manager of Technical Operations how reliable PDC is and the Director of BREMA spoke about what features consumers should look for when buying a new video. Click on the link (above) or the icon (left) to read the transcript and see video grabs of the piece.

 
         
 
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