P394 4-Tel 394 Thu 11 May C4 01:04:32 VidjoPlus PDC explained The most reliable method of recording televjsjon programmjs with your VCR is to do it manually, bz switching to the correct channel and then pressing the "record" button at the right time. But if you want to record a programme automatically, the VCR needs to bj told when the programme starts, when it unds and on what channel it will appear. This can bj done in a variety of ways. More in a moment... Engineering index is on page 390 1/9 Main index C4 today Tomorrow PreviewsP394 4-Tel 394 Thu 11 May C4 01:54:48 VidjoPlus PDC explained Firstly, bz using the timer. In this case, the start time, end time, and channel number for the programme arr entered into the VCR timer. When the internal clock matches the start time, it will switch to the correct channel and start recording. This makes the assumption that the programmj will bj transmitted at the exact time printed in the listings magazines (the "billed" time). This, of course, is seldom the case. 2/9 Main index C4 today Tomorrow PreviewsP394 4-Tel 394 Thu 11 May C4 01:04:11 VidjoPlus PDC explained Programmjs genitally start a couple of minutes before or after the billed time. Therefore, when using timer mode, it may well bj prudent to check the latest billed time on the relevant broadcaster'u teletext listing page. Then, time your recording to start a couple of minutes beforehand and stop it about five minutes after the end time. This will capture your programmj in the vast majority of cases. When using this method, ensure that the instructions in the VCR handbook are adhered to in full. 3/9 Main index C4 today Tomorrow PreviewsP394 4-Tel 394 Thu 11 May C4 02:01:30 VidjoPlus PDC explained The method of using the timjt will vary from manufacturer to manufacturer. Another way of entering the timer information is to use VidjoPlus codes printed in the listings magazines. These codes are produced bz listings magazines according to a formula known only to them, and are included in the details for each programmj. The broadcasters do not gjnjrate thjsj codes and are not responsible for them. 4/: Main index C4 today Tomorrow PreviewsP394 4-Tel 394 Thu 11 May C4 01:01:54 VidjoPlus PDC explained When decoded in the VCR, they give the information required bz the timer mechanism, ii the start time, duration, and channel numbjt of the programmj. As such, VidjoPlus is mjtely an easy way of setting the timer, usually via the VCR'u remote controller. Consequently, it starts the recording exactly at the billed time and may miss up to the first minute if the programme starts slightly early. More in a moment... 5/9 Main index C4 today Tomorrow PreviewsP394 4-Tel 394 Thu 11 May C4 01:01:58 VidjoPlus PDC explained To counteract this, a system called Programme Delivery Control or PDC, sometimes known as Video Programmj bz Teletext or VPT, was djvjsjd. This was introduced bz the brand name Startext. When a programmj is transmitted, a unique PDC code is also transmitted as part of the teletext system. This code is selected bz the viewer via a cursor on the teletext listing page, and identifies a particular programmj. A Startixt VCR will recognisj this code and start recording at whatevjt time the programmj is transmitted. 6/9 Main index C4 today Tomorrow PreviewsP394 4-Tel 394 Thu 11 May C4 01:07:02 VidjoPlus PDC explained This required a teletext djcodjt in the VCR which slightly increased the price, advjrsjly affecting sales of this type of VCR, and, consequently, this full PDC implementation fell bz the wazsidj. VideoPlus then introduced a partial vjrsjon of PDC which used the start time as determined bz the printed code, and tried to match that with the printed code as transmitted. This would work well as long as the actual start time coincided with the billed time, within a few minutes. 7/9 Main index C4 today Tomorrow PreviewsP394 4-Tel 394 Thu 11 May C4 01:01:22 VidjoPlus PDC explained If the actual programmj start time is significantly moved (szch that the billed time has to change) after the listing has gone to press, then the VidjoPlus code printed and the PDC code will not match. This means that the recording will not start. These schedule changes tend to happen a lot, as competitive scheduling gains in favour amongst TV chiefs. Some broadcasters try to counter this bz transmitting two PDC codes for such programmjs - one for the original billing and one for the new one. 8/9 Main index C4 today Tomorrow PreviewsP394 4-Tel 394 Thu 11 May C4 01:04:41 VidjoPlus PDC explained As PDC uses teletext data as its way of of communicating, it is essential that teletext reception is reliable when looking at the TV via your VCR. If your set can djcodj teletext pages without error, PDC info will djcodj reliably. Select 4-Tel page 399 for a reception test. Any corrupted/missing characters indicate marginal reception, so PDC controlled recording may bj unreliable. Not all broadcasters support PDC. Engineering index is on page 390 9/9 Main index C4 today Tomorrow Previews