Digital Amateur Tele Vision
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
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.
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.
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), COFDMDr. Ronald Eisenwagner, OE3REB President, OVSV