HDTV & The Explorer

July 3, 2006.

HDTV: A Short description

High Definition Television is a new TV format that intends to display video information with higher resolution than conventional TV.

After a long period of time with confusing technical information about HDTV, the industry has now agreed on the exact meaning of HDTV.

TV sets, based on CRT, TFT or plasma technologies, are compatible with HDTV and can consequently carry the label “HD READY” only if they are compliant with the certain technical requirements (see below).

HDTV is broadcast using digital television techniques only. The HDTV video signal must be processed to prepare it for transmission.

Technical requirements for HDTV

  • Minimum vertical resolution of 720 lines in 16:9 format
  • Input for HDTV via:
    • YPbPr (analogue components)
    • DVI or HDMI
  • HDTV inputs must accept minimum following video formats:
    • 1280x720 @50 and 60 Hz with progressive scan (“720p”)
    • 1920x1080 @50 and 60 Hz with interlaced scan (“1080i”)

Transmission processes for HDTV

  • Digital compression: Signal is converted into digital and compressed to reduce the amount of bandwidth required for transmission. Two techniques are used, MPEG-2 and MPEG-4. As a result we obtain a TS (Transport stream).
  • Modulation: The TS is prepared to be broadcasted over the transmission channel.
    • Terrestrial: DVB-T COFDM
    • Cable: DVB-C QAM
    • Satellite: DVB-S QPSK, DVB-S2 QPSK / 8PSK

HDTV Channels available now

Nowadays HDTV programmes can be received in the UK via satellite only. Astra 19E, Eutelsat 13E or Astra 23E offer a selection of transponders with HDTV content. With the World cup event coming up shortly BBC has announced that a DTT HDTV trial, limited to a few hundred households in London which have yet to be chosen, will take place. But other than this satellite is the only option.

If we take Hot bird Eutelsat 13E for example the following transponders offer HDTV content:

TXD 116

DVB-S

MPEG-4/HD

TXD 2

DVB-S

MPEG-4/HD

TSC 64

DVB-S2

MPEG-4/HD

HDTV & the TV Explorer

The PRODIG-5 TV Explorer is compatible with DVB-S so it can make measurements on HDTV channels using this modulation scheme.

This is the case of TXD's 116 and 2 and is independent of whether the programmes are compressed in MPEG-2 or MPEG-4. The service list will indicates the presence of HDTV services.Currently, power and C/N measurements can be carried out on TXD's using DVB-S2. No digital measurements such as MER, CBER, VBER can be made at present. However, because of the nature of satellite transmission, measurements taken at neighbouring channels can also be representative.

Spectrum for one ASTRA’s HDTV channels
Spectrum for one ASTRA’s HDTV channels

Following is a list of some satellite TXD's currently using DVB-S:

  • ASTRA 19.2 E
    TXD 88
    TXD 110
  • ASTRA 23.5 E
    TXD 52
    HOT BIRD 13.0 E
    TXD 116
    TXD 2
    TXD 12
  • ATLANTIC BIRD 5.0 W
    TXD KC2