DARC
Berg. Universitšt Wuppertal
AGAF e.V.

Digital  Amateur  Tele Vision



(mirror/Spiegel of DATV/DHTV-News-Group)

As some of you know, I'm going to Tel Aviv for the 1996 IARU Region 1 Conference, Sep 29 - Oct 6. One of the input papers is from the Austrian society (OVSV), written by OE1MCU and OE5MLL, and is quoted below with OE3REB's permission "to do whatever we wish with it." I'll report to you about the discussion of this paper subsequent to my trip.

73, Paul, W4RI 


Proposal for usage of Digital ATV in the 70 cm band

Introduction:

With MPEG1 and MPEG2, ISO defined standards for digital moving picture and sound transmission. We expect that MPEG1 will be established as the PC video standard and MPEG as the standard for European digital television in the future.

Examples:

o Already a large number of graphic cards conforming to the MPEG1 standard is available for PCs. o Astra 1E transmits in the MPEG2 standard.

Proposal:

OVSV therefore moves that, in the 70cm band, IARU Region 1 establish a 2 MHz subband between 433 MHz and 435 MHz for digital moving picture and sound transmission (DATV) and other new digital transmissions parallel to the existing analogue ATV allocation according to CCIR.

Reasons:

This motion would pave the way for digital ATV according to MPEG1 or MPEG2.

Because of the increasing usage of the 70 cm band, C3F (ATV) with a bandwidth of 6.25 MHz is no more possible.

By using digital moving picture and sound transmissions in the sub-band between 433 and 435 MHz, ATV can be preserved as an operating mode in the 70cm band in the long run.

Appendix:

Overview of MPEG Digital Video
Standard        Application



MPEG1           Digital video for PCs

MPEG2           Digital Video Broadcasting (e.g. ASTRA 1E)

MPEG3           High definition TV (has been integrated

                into MPEG2)

MPEG4           Picture transmission via modems using 

                64 kB ISDN, low picture quality



Detailed information on MPEG1:

o Video and audio compression

o Compressed data rate: approx. 155 KBytes/s=1.24 Mbit/s

o Compression factor: 1:20 to 1:200 (redundancy and

  irrelevancy reduction)

o Required bandwidth per channel: approx. 0.3 MHz

o Transmission quality: comparable to VHS

o Video:

  Resolution 352 * 288 pixels (PAL)

  24/25/30 pictures/sec, 65.536 or 16.7 million colours

o Audio:

  Layer I (as DCC), layer II (Musicam, CD quality)

o Standards: MPEG1 has been standardized in 

  ISO/IEC 11272

o Cutting of MPEG1 videos is possible on the PC



Detailed information on MPEG2:

o Video and autio compression

o Compressed data rate: 500-750 KBytes/s=4-6 MBit/s

o Compression factor: 1:20 to 1:200 (redundancy and

  irrelevancy reduction)

o Required bandwidth per channel: 1.5-2 MHz

o Transmission quality: studio quality

o Video:

  max. resolution 1920 * 1152 pixels (HDTV)

  Interlaced pictures can be transmitted

o Audio:

  layer I (as DCC), layer II(Musicam, CD quality),

  layer III multiple channel stereo

o Standards: MPEG2 has been standardised in 

  ISO/IEC 13818

o The picture quality is automatically adapted to the

  signal quality.

Appendix:

Calculation of channel bandwidth:

B=R/E

B..... channel bandwidth [MHz]

R..... bit rate [Mbits/s]

E..... spectral efficiency [ ], typical 3 - 5

       depending on the modulation: 

       QPSK (Satellite), QAM (cable), COFDM
Dr. Ronald Eisenwagner, OE3REB President, OVSV 
aa4hs@amrad.org