DSO-2 Completed

I hope you have either already retuned or will retune today all your Freeview tv receivers. That will bring in the D3&4 Mux at the full power of 200kW, so if you've previously had problems receiving stations like ITV-1, C4 and C5 you should now be watching uninterrupted pictures. Don't forget the final retune you will have to do is on 18 April, if you are receiving from Rowridge but not if you are receiving from a relay transmitter or from the Mendip transmitter. Difficulty in receiving other stations now may well be cured at that time.

If you have a high definition Freeview receiver you will now also be able to receive, for the first time via terrestrial television, the four high definition stations: BBC-1 HD, BBC HD, ITV-1 HD and C4 HD. There are two points about these high definition stations which are relevant.

1. They are being transmitted from Rowridge on channel 21. This is the lowest channel in the UHF spectrum and the one to which a Group A aerial is least sensitive. Don't be concerned, therefore, if your equipment shows slightly lower signal strength and/or quality than for the standard definition stations. It may be between 10 and 20% lower but should still provide a stable picture and sound, unless you are near the "cliff edge" for the standard definition channels. In which case you may have some problems.

2. Only BBC HD at presents transmits all high definition sourced programmes. That means they are made in high definition. Because the other three high definition stations are HD versions of their standard definition counterparts, not all their programmes will have been made in high definition. Usually the listings magazines will include the letters "HD" in their description of a programme made in high definition. If those letters are not included it indicates the programme was made in standard definition. You will need to check that your listings magazine does use that identifier.

A programme made in standard definition is upscaled prior to transmission on a high definition channel. That doesn't make it high definition but just ensures it fills your tv screen completely. Your tv does that upscaling to all the standard definition stations you tune into anyway.  It makes little difference whether you use the high definition station or the standard definition station to view a standard definition programme, but it does have a significance when using a PVR (Personal Video Recorder) to record such a programme.

If you record a standard definition sourced programme from the high definition station it will take up as much space on your PVR's hard disc as if it were a true high definition programme, which is a bit of a waste of space. You might just as well record it from the standard definition station and let your tv upscale for you. That way the programme will take up only about 25% of the space on your hard disc which recording from the high definition station would have occupied, with no disadvantage in picture quality.