DATV Digital Amateur Television Current Status and Future Activities 2000, Friedrichshafen, June 2000 Uwe E. Kraus / PA3ACY University of Wuppertal / Germany -1-
Overview DATV Current Status and Future Activities - Why going digital in Amateur Television? Objectives of DATV - Modulation Scheme Chosen *GMSK * Alternatives: OFDM, m-vsb - Frequency Bands for DATV - DATV Project-Group at Wuppertal University * Hardware Development *FieldTests * Availability of PCB`s and Components * Future Developments - Claiming Frequencies for DATV 2000-01 Overview
Why Going Digital? Objectives for DATV - Significantly reduced RF - bandwidth - Longer range with same power and picture quality - More robust against channel distortions - Shaping the RF - spectrum for minimum interference with other services in adjacent channels - Combination with other digital transmission modes (e.g. Packet Radio with higher data rates) - Combination with modern Multimedia - Technologies - Suited for space communications 2000-02 Why Going Digital
Modulation Scheme Chosen: Gaussian Minimum Shift Keying, GMSK Advantages - Excellent performance in mobile communications (GSM) - Compact spectrum - Similar to FM - Non linear, highly effective RF - amplifiers can be used (Class C - operation) - Easy to build encoder and modulator - Easy demodulation in the receiver, FM - demodulator, improvement by coherent demodulation possible (ca. 3 db) 2000-03 Modulation Scheme (1)
Advantages (continued) - ca. 2 Mbit/s data rate in 2 MHz analog RF bandwidth at 70 cm, 434 MHz center frequency, MPEG 1 (Video - CD quality) or low data rate MPEG 2 - Broadcast quality MPEG 2 transmission in 6 MHz through 8 MHz analog RF - bandwidth at 23 cm and higher Amateur bands - No Doppler shift problems in space communications expected Disadvantage: - relatively low bit rate per Hertz analog bandwidth 2000-04 Modulation Scheme (2)
Data Signal Instant Frequency 2000-05 Frequency- and Phasevariation GMSK vs MSK Leh rstuhl für N achric ni k htentech
2000-06 I/Q- Diagram B xt=0,3 rstuhl für N achric Leh htentech ni k
2000-07 Eye Pattern of GMSK with B*T = 0,3 rstuhl für N achric Leh htentech ni k
2000-08 Transmission Spectrum
Alternative Modulation Schemes - Orthogonal Frequency Division Multiplex, OFDM - Eight level Vestigial Sideband, 8 - VSB Advantages - Higher data rate per Hertz bandwidth - ca. 5 Mbit/s in 2 MHz bandwidth at 70 cm, broadcast quality MPEG 2 transmission - Almost rectangular frequency spectrum Disadvantages - more complex circuitry in both transmitter and receiver - Higher S/N required, more transmission power needed - Highly linear RF - amplifiers required (high linearity, high power and high frequencies are a difficult combination) 2000-09 Modulation Scheme (3)
Frequency Bands for DATV 70 cm Band - 70 cm band is essential for DATV - DX - 2 MHz of RF - bandwidth available, 433 MHz - 435 MHz (ISM), proposed for broadband digital transmissions by DARC since serveral years -70cmoffers: * optimum DX without relais * easy to handle antennas, moderate cable losses, effective RF - power generation * interesting propagation studies * home made equipment realizable for a lot of amateurs * coexistance of DATV and other analog and digital modes * GMSK can be used to start with and for difficult propagation situations, OFDM and 8 - VSB might be used for higher picture quality under nice weather conditions 2000-10 Frequency Bands for DATV
Higher Frequency Bands 23 cmandshorter: * higher bandwidth available for wider and / or more DATV channels for broadcast quality pictures and Duplex - operation * short range connections * relais - operation 2000-11 Frequency Bands for DATV (continued)
DATV Project Group at Wuppertal University - Group started officially on December, 10 1998 - Sponsored by DARC and four Districts in Northrhine Westfalia (Duesseldorf / Cologne / Dortmund area) - Tasks: * development of a 1. Generation DATV transmitter and receiver based on tests and experiences gained earlier (done) *PC-basedVideoandAudiogenerationand reproduction for the time being to be replaced by stand-alone hardware later (done) * production of four transmitters and four receivers for field tests to be delivered in December 1999 to the Districts (done) *eight more receivers to follow (almost ready) 2000-12 DATV Project Group at Wuppertal University (1)
DATV Project Group at Wuppertal University - General Design Ideas * modular system * logical signal interfaces * 50 Ohm coax technique * single 12 Volt (11 Volt - 14 Volt) operation, (single standard power supply, car battery) Hardware Development - see block diagram, shaded blocks: 1. Generation, other blocks to be added 2000-13 DATV Project Group at Wuppertal University (2)
l 434 MHz 36,2 MHz 70 cm Converter IF +Demod. Slicer, Clock- Regeneration FEC -1 Remodulator QPSK 1GHz Dig. Satellite PAL Set-Top Box / RGB 100W LO-Input S-Meter Eye Pattern PA Channel Equalizer Slicer,Clock- Regeneration FEC -1 470,2 MHz 10 W FM Power Module 434 MHz 10 mw 434MHz Up- Converter Synth. 4MHz Reference 36,2 MHz GMSK-IF GMSK Modulator 36,2 MHz Frequency-Display Frequency-Adjustment I Q GMSK Encoder FEC IC 2 PAL/MPEG Transcoder Source Select PC + Insertion Board MPEG Software Decoder (S)VHS PAL/YC 601 2000-14 DATV - Transceiver Modules - Overview L e h B er gisch e r st u h U n l fü iv er r N sit ä t a ch r G H i c -W h t en u p p er t a t ech n i k
DATV Project Group at Wuppertal University Field - Tests on 70 cm - Previous field - tests * short range in Wuppertal area to show the feasibility * 50 km: Wuppertal to Kamp-Lintfort * 100 km: Wuppertal (JO31NF) to Someren / NL (JO21UJ) - Current field - tests * take place in the four Districts using the equipment of the Project Group to gain experience about propagation and equipment to furtilize the development of the next generation - Long Distance Test * Wuppertal to Brussels over 234 km in preparation, preliminary test using 100 Watt and FM audio gave encouraging results, tests with DATV data to follow soon 2000-15 DATV Project Group at Wuppertal University (3)
DATV Project Group at Wuppertal University Availability of PCB`s and Components - DARC offers to provide the distribution of PCB`s and difficult to get components in a non profit way (still to be arranged) Current Developments for 2. and further Generations of DATV - PAL / NTSC / SECAM to MPEG2 transcoder for PC-less transmission status: ready - MPEG 2 to QPSK - remodulator (digital satellite standard according to DVBS) to use a standard digital TV set-top box for MPEG decoding and conversion to PAL and/or RGB (SCART) status: ready - Forward Error Correction, FEC status: prototype working - Channel Equalizer status: prototype working - Stand-alone Harddisk recorder for several hours MPEG programs status: prototype working - OFDM and 8-VSB encoder with adjustable RF - bandwidth, 2 MHz - 8MHz status: 8-VSB prototype working OFDM simulation ready, hardware in progress 2000-16 DATV Project Group at Wuppertal University (4)
Claiming Frequencies for DATV - DATV is a future oriented technique having the potential to attract new young amateurs being familiar with computers and multimedia hardware and software - DATV must be an issue at future IARU frequency allocation conferences - National Amateur Radio Clubs need to come up with proposals for a bandplan taking DATV into account - 433 MHz - 435 MHz should be used for DATV and other broadband digital services only - see questionable Proposed New IARU Region 1 Bandplan for 432-435 MHz as a not acceptable example - see appendices for next generations and claimed frequencies for DATV on 70cm and higher bands 2000-17 Claiming Frequencies for DATV
IARU REGION 1 CONFERENCE 1999 Annex 3 to Doc/99/LH/C5.31 EXISTING IARU REGION 1 BANDPLAN FOR 432-435 MHz: FM 432 433 SIMPLEX 434 435 CW SSB ALL MO DIG BEAC REPEATER IN DIG ALL MODES DIG REPEAT OP 000 150 500 700 800 000 600 800 000 450 600 000 NARROW NARROW CALL CW SSB xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx PROPOSED NEW IARU REGION 1 BANDPLAN FOR 432-435 MHz: 432 433 434 CTCSS 435 BEAC DIG REPEATER IN FM SIMPLEX DIG ALL MODES DIG 000 100 300 500 600 000 600 800 000 450 600 800 000 NARROW CALL REP xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxx FM repeater split 2 MHz; 16 channels: 432.600/434.600; 626; 650; 675; 700; 725; 750; 775; 800; 825; 850; 875; 900; 925; 975. Repeater frequencies given in italics ISM ISM can be used with CTCSS (sub-audible tone squelch system) to help reducing the ISM interference. OP 2000-18 IARU Region 1 Bandplan for 432-435 MHz
- 1. Generation DATV - 2. Generation DATV (current one) - 3. Generation DATV (cheaper solution, kit) - Further developments for future Generations - Frequency claims for 70cm and higher amateur bands 2000-19 Appendices (Status June 2000)
Data Clock Transmitting-PC with Interface-Card MPEG-Video-CD GMSK Coder I Q Oscillator BP SAW 36,2MHz Oscillator 434MHz 10mW 470,2MHz 434MHz 10W 434MHz 100W Transmitter 434MHz IF + Demodulator Slicer Clock- Recovery Data Clock Oscillator 470,2MHz Receiver Receiving-PC with Interface-Card MPEG-Software Decoder 2000-20 1. Generation DATV Transmission Tests with Digital Modulation (GMSK) at 70cm (433MHz - 435MHz)
434MHz Camcorder PAL MPEG 2 FEC MPEG 2 Interface Transportstream GMSK Coder I Q Oscillator BP SAW 36,2MHz Oscillator 434MHz 10mW 470,2MHz 434MHz 10W 100W Transmitter 434MHz IF + Demodulator Slicer Clock- Recovery MPEG 2 Transportstream Data Clock QPSK DVB-S Set-Top Box FEC- and MPEG 2 Decoder PAL RGB Monitor Oscillator 470,2MHz Oscillator 1152MHz Receiver Re-Modulator 2000-21 2. Generation DATV Live-Transmission with Camera and Real Time Reproduction
Sub-D MPEG 2 Interface Transportstream 8 Bit, Clock FEC GMSK-Coder (MSK, QPSK) digital I digital Q Digital Filter Digital I/Q Modulator GMSK 36,2MHz LP 470,2MHz 434MHz 10mW 156,733MHz Oscillator 52,244MHz Transmitter (Mono Carrier, Euro-Format) Antenna 434MHZ 36,2MHz SAW SAW FM Demodulator Slicer Clock- Recovery MPEG 2 Transportstream Data Clock QPSK to DVB-S Set-Top Box 470,2MHz IF-Output Oscillator 52,244MHz S-Meter Converter IF Demodulator 1152MHz Oscillator Re-Modulator Receiver (Mono Carrier, Double Euro-Format) 2000-22 3. Generation DATV New Cheap Concept for Easy Reproduction
- Improved MPEG-2 coder with digital sound - Improved error correction and echo cancellation - Use of H263, MPEG4, MPEG7 - Use of higher frequency bands - More RF-bandwidth for higher data rates (4MHz, 6MHz for approx.3,5mbit/s to 5Mbit/s with GMSK) - Test of other modulation schemes QAM, OFDM, n-vsb for 2MHZ, 4MHz, 6MHz RF-bandwidth - Antenna tests and propagation tests at 70cm and higher bands 2000-23 Further Developments for Future Generations
430Mhz 433Mhz 435Mhz 440Mhz 1240MHz 2320MHz 3400MHz 5650MHz 10000MHz 1243MHz 2322MHz 2355MHz 5700MHz 1260MHz 10150MHz 2370MHz 5720MHz 10200MHz Digital broadband mode ( DATV etc ) 1272MHz 2392MHz 3450MHz 5790MHz 10370MHz 1291MHz 5810MHz 10420MHz Other modes - Proposals for DATV-frequencies according to the valid band plan ( DARC-VUS report, valid from 07/1997 ) - Transit from AM- to FM-ATV to DATV floating corresponding to technical progress 1300MHz 2450MHz 3475MHz 5850MHz 10500MHz 70cm Band State: primary 23cm Band State: secondary 13cm Band State: secondary 9cm Band State: secondary 6cm Band State: secondary 3cm Band State: secondary 2000-24 Frequency Claims for Digital Broadband Systems (DATV etc.)