Silicon ChipAmateur Radio - July 1990 SILICON CHIP
  1. Outer Front Cover
  2. Contents
  3. Publisher's Letter: The story of electrical energy
  4. Vintage Radio: How to solve unusual problems by John Hill
  5. Review: AR950 100-Channel Scanner by Garry Cratt
  6. Project: Digital Sine/Square Wave Generator; Pt.1 by John Clarke
  7. Project: Alarm Keypad & Combination Lock by Greg Swain
  8. Project: Build An Elegant Electronic Die by Darren Yates
  9. Serviceman's Log: The dangers of a quick fix by The TV Serviceman
  10. Back Issues
  11. Feature: The Story Of Electrical Energy by Bryan Maher
  12. Feature: Waveform Generation Using A PC, Pt.4 by Steve Payor
  13. Feature: Computer Bits by Jennifer Bonnitcha
  14. Project: Low Cost Dual Power Supply by John Crichton
  15. Feature: Amateur Radio by Garry Cratt, VK2YBX
  16. Market Centre
  17. Advertising Index
  18. Subscriptions
  19. Outer Back Cover

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Items relevant to "Digital Sine/Square Wave Generator; Pt.1":
  • Digital Sine/Square Wave Generator PCB patterns [04108901/2] (Free)
  • Silicon Chip article scan, July 1990 - Digital Sine/Square Wave Generator; Pt.1 (AUD $10.00)
Articles in this series:
  • Digital Sine/Square Wave Generator; Pt.1 (July 1990)
  • Digital Sine/Square Wave Generator; Pt.2 (August 1990)
Articles in this series:
  • The Technology Letters, Pt.2 (January 1989)
  • The Story Of Electrical Energy (July 1990)
  • The Story Of Electrical Energy; Pt.2 (August 1990)
  • The Story Of Electrical Energy; Pt.3 (September 1990)
  • The Story Of Electrical Energy; Pt.4 (October 1990)
  • The Story Of Electrical Energy; Pt.5 (November 1990)
  • The Story Of Electrical Energy; Pt.6 (December 1990)
  • The Story Of Electrical Energy; Pt.7 (January 1991)
  • The Story Of Electrical Energy; Pt.8 (February 1991)
  • The Story Of Electrical Energy; Pt.9 (March 1991)
  • The Story Of Electrical Energy; Pt.10 (May 1991)
  • The Story Of Electrical Energy; Pt.11 (July 1991)
  • The Story Of Electrical Energy; Pt.12 (August 1991)
  • The Story Of Electrical Energy; Pt.13 (September 1991)
  • The Story Of Electrical Energy; Pt.14 (October 1991)
  • The Story Of Electrical Energy; Pt.15 (November 1991)
  • The Story Of Electrical Energy; Pt.16 (December 1991)
  • The Story Of Electrical Energy; Pt.17 (January 1992)
  • The Story Of Electrical Energy; Pt.18 (March 1992)
  • The Story Of Electrical Energy; Pt.19 (August 1992)
  • The Story of Electrical Energy; Pt.20 (September 1992)
  • The Story Of Electrical Energy; Pt.21 (November 1992)
  • The Story Of Electrical Energy; Pt.22 (January 1993)
  • The Story of Electrical Energy (April 1993)
  • The Story Of Electrical Energy; Pt.24 (May 1993)
  • The Story Of Electrical Energy; Pt.24 (June 1993)
Articles in this series:
  • Computer Bits (February 1990)
  • Computer Bits (March 1990)
  • Waveform Generation Using A PC, Pt.3 (May 1990)
  • Waveform Generation Using A PC, Pt.4 (July 1990)
Articles in this series:
  • Computer Bits (May 1990)
  • Computer Bits (June 1990)
  • Computer Bits (July 1990)
  • Computer Bits (August 1990)
  • Computer Bits (September 1990)
Articles in this series:
  • Amateur Radio (November 1987)
  • Amateur Radio (December 1987)
  • Amateur Radio (February 1988)
  • Amateur Radio (March 1988)
  • Amateur Radio (April 1988)
  • Amateur Radio (May 1988)
  • Amateur Radio (June 1988)
  • Amateur Radio (July 1988)
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  • Amateur Radio (January 1989)
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  • Amateur Radio (June 1989)
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  • Amateur Radio (March 1990)
  • Amateur Radio (April 1990)
  • Amateur Radio (May 1990)
  • Amateur Radio (June 1990)
  • Amateur Radio (July 1990)
  • The "Tube" vs. The Microchip (August 1990)
  • Amateur Radio (September 1990)
  • Amateur Radio (October 1990)
  • Amateur Radio (November 1990)
  • Amateur Radio (December 1990)
  • Amateur Radio (January 1991)
  • Amateur Radio (February 1991)
  • Amateur Radio (March 1991)
  • Amateur Radio (April 1991)
  • Amateur Radio (May 1991)
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  • Amateur Radio (July 1991)
  • Amateur Radio (August 1991)
  • Amateur Radio (September 1991)
  • Amateur Radio (October 1991)
  • Amateur Radio (November 1991)
  • Amateur Radio (January 1992)
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  • Amateur Radio (July 1992)
  • Amateur Radio (August 1992)
  • Amateur Radio (September 1992)
  • Amateur Radio (October 1992)
  • Amateur Radio (November 1992)
  • Amateur Radio (January 1993)
  • Amateur Radio (March 1993)
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  • Amateur Radio (June 1993)
  • Amateur Radio (July 1993)
  • Amateur Radio (August 1993)
  • Amateur Radio (September 1993)
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  • Amateur Radio (December 1993)
  • Amateur Radio (February 1994)
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  • Amateur Radio (June 1994)
  • Amateur Radio (September 1994)
  • Amateur Radio (December 1994)
  • Amateur Radio (January 1995)
  • CB Radio Can Now Transmit Data (March 2001)
  • What's On Offer In "Walkie Talkies" (March 2001)
  • Stressless Wireless (October 2004)
  • “Degen” Synthesised HF Communications Receiver (January 2007)
  • WiNRADiO: Marrying A Radio Receiver To A PC (January 2007)
  • PICAXE-08M 433MHz Data Transceiver (October 2008)
  • Half-Duplex With HopeRF’s HM-TR UHF Transceivers (April 2009)
  • Dorji 433MHz Wireless Data Modules (January 2012)
AMATEUR RADIO By GARRY CRATT, VK2YBX Weather fax - what frequencies to listen to Our Radfax Decoder project in November has aroused much interest in the reception of weather fax signals from both amateurs and meteorologists alike. This article sets out to explain the origin of both HF and satellite signals and lists where and when they can be heard. Facsimile, in comparison to other modes of image transmission, offers a significantly higher degree of resolution than other less used modes such as slow scan TV (SSTV) and fast scan TV. This resolution, often between 1000 and 2000 lines per frame, means that extremely high quality images can be transmitted within the limitations of audio bandwidth, either down a telephone line or, of more interest to amateurs, via HF radio. As the time taken to transmit each frame is really of no consequence, detailed pictures can be received using a communications receiver and either a decoder for use with a computer, or a dedicated "receive only" fax unit. As a result, HF fax transmission is used in many countries for the distribution of weather charts for use by aviators, mariners and other interested parties. A modern fax transmitter electronically scans the sheet of text inserted and uses the voltage variations obtained to modulate an audio subcarrier, using either AM or FM modulation. Some transmitters use positive modulation, where the amount of modulation is determined by the amount of white (100% is all FIG.1: LIST OF SATELLITES TRANSMITTING WEATHER INFORMATION 88 FREQUENCY TYPE 137.500MHz 137.620MHz 137.300MHz 137.400MHz 137.850MHz 137.850MHz 1691.00MHz 1691.00MHz 1691 .00MHZ 1694.50MHz POLAR POLAR POLAR POLAR POLAR POLAR GEOST GEOST GEOST GEOST SILCON CHIP ORIGIN LINE RATE USA-NOAA 6 USA-NOAA 9 USSR-METEOR 2-14 USSR-METEOR 2-14 USSR-METEOR 2-14 USSR-METEOR 3-1 USA-GOES 5 USA-GOES 2 USA-GOES 3 ESA-METOESAT 2 120 120 120 120 120 120 240 240 240 240 INCLINATION 98 98 82 82 82 82 75 114 135 180 DEGREES DEGREES DEGREES DEGREES DEGREES DEGREES DEGREES DEGREES DEGREES DEGREES PERIOD W W W E 102MIN 102MIN 104MIN 104MIN 104MIN 11 OMIN 24HRS 24HRS 24HRS 24HRS white), while others use negative modulation, which is the reverse relationship to the material scanned. Typically, FM subcarrier modulation is used for HF transmissions as it offers some immunity to fading problems. Critical parameters The critical specifications for all fax transmissions are drum speed and scanning density. The subcarrier modulation type must also be known. Drum speed is expressed in RPM and relates to the original mechanical scanning systems used years ago. Most dedicated fax receivers allow selection of the two most commonly used speeds: 60 lines per minute and 120 lines per minute. Other rates sometimes used are 100 1pm, 180 1pm and 240 1pm. Scanning density refers to the number of lines per inch, which determines the linearity of the display. These values are often expressed as the IOC value (index of co-operation) and relate to the height to width ratio of the image. In addition to the HF fax broadcasts, there are a number of geostationary and polar orbiting weather satellites transmitting picture information in the VHF and SHF bands. The broadcasts that interest most amateurs are the APT or automatic picture transmissions. These are capable of an image resolution of 2-3km under good lighting conditions and are relatively easily received on modified 2-metre equipment or scanning receivers. Fortunately, all major users of cc ~· a co co ,-..,. -< t- c::: .._ CANBERRA AUSTRALIA CHINA CHILE BULGARIA CANADA BRAZIL BUENOS AIRES ARGENTINA BEIJING SANTIAGO BELLOTO RESOLUTE HALIFAX FROBISHER BAY SOFIA ESGUIMALT RIO DE JANEIRO BRASILIA DARWIN CITY COUNTRY BAF6 BAF36 ccs ccs ccs ccs ccs ccs ccs ccs ccs LR069 LR072 LR074 AXM31 . AXM32 AXM34 AXM35 AXM37 AXl32 AXl33 AXl34 AXl35 AXl36 PPN9 PPN9 PWZ PWZ LZJ2 CKN CKN VFF VFF CFH CFH CFH CFH VFR VFR CCV6 CCV6 CCV6 CCV6 CCV6 CALLSIGN IOC 576 576 576 576 576 576 576 576 576 576 576 576 576 576 576 576 576 576 576 576 576 576 576 576 576 576 576 576 576 576 576 576 576 576 576 576 576 576 576 576 576 576 576 576 5185.00 10720.00 18093.00 2628.00 5100.00 11030.00 13920.00 19690.00 5755.00 7537.00 10555.00 15615.00 18060.00 10225.00 18080.00 12025.00 17140.00 5093.00 4268.00 6946.00 3235.00 7710.00 4271 .00 6330.00 10536.00 13510.00 3253.00 7710.00 4766.00 6418.00 8594.00 13525.00 22071.00 2716 .00 2886.00 4063.00 6418.00 8692.00 8776.00 12600.00 13525.00 22070 .00 5525.00 8120.00 120 120 120 120 120 120 120 120 120 120 120 120 120 120 120 120 120 120 120 120 120 120 120 120 120 120 120 120 120 120 120 120 120 120 120 120 120 120 120 120 120 120 120 120 FREQUENCY RPM ITALY ROMA NEW DELHI OUICKBORN ATHENS GREECE INDIA PINNEBERG HELSINKI PARIS GERMANY FINLAND FRANCE NORTHWOOD BRACKNELL CAIRO EGYPT ENGLAND COPENHAGEN CITY DENMARK COUNTRY FIG.2: LIST OF CURRENT HF FAX TRANSMISSIONS BAF4 BAF8 BAF33 OXT OXT OXT OXT SUU36 SUU2 GFA21 GFA22 GFA23 GFA24 GFA25 GFE25 GFE21 GFE22 GFE23 GFE24 GYA1 GYA6 GZZ2 GZZ3 GZZ40 OFB28 FTE4 FTl8B FTM30 DDK3 DDK6 DDH3 MGR MGR MGR ATP38 ATP38 ATA55 ATA57 ATV65 ATV65 IMB51 IMB55 IMB56 CALLSIGN 10115.00 14365.00 18235.00 5850.00 9360.00 13855.00 17510.00 4526.00 10123.00 3289.50 4610.00 8040.00 11086.50 14582.50 2618.50 4782.00 9203.00 14436.00 18261.00 2813.85 3436.85 4247.85 6436.85 8494.85 8018.00 4047 .50 8185.00 12305.00 7880.00 13882.50 3855 .00 5206.00 8100.00 12903.00 18227.00 18233.00 4933.50 7405.50 14842.00 14772.00 4777.50 8146.00 13600.00 continued IOC 120 576 120 576 120 576 120 576 120 576 120 576 120 576 120 576 120 576 120 576 120 576 120 576 120 576 120 576 120 576 120 576 120 576 120 576 120 576 120 576 120 576 120 576 120 576 120 576 120 576 120 576 120 288 120 288 120 576 120 576 120 288 120 576 120 576 120 576 120 576 120 576 120 576 120 576 120 576 120 576 120 576 120 576 120 576 next page FREQUENCY RPM :!:: -c n r=: 0 0 :z: CJ) C0 0 I AUCKLAND MONSANTO ST DENISCHAUDRON DAKAR PRETORIA MADRID NEW ZEALAND PORTUGAL REUNION SENEGAL SOUTH AFRICA SPAIN SWEDEN FORT DE FRANCE MARTINIQUE NORRKOPING ROTA NAIROBI TOKYO JAPAN KENYA CONTINUED CITY FIG.2 COUNTRY CALLSIGN JMH JMH JMH JMH JMH JMH JMJ JMJ JMJ JMJ JMJ 5YE 5YE 5YE3 5YE3 FFP FFP ZKLF ZKLF ZKLF ZKLF CTV4 CTW8 CTU2 HXP FZS63 6VY41 6VU73 6VU79 ZR05 ZR02 ZR03 ZR04 AOK AOK AOK AOK AOK AOK AOK AOK AOK SMA4 SMA6 SMA8 3622.50 7305.00 9970.00 13597 .00 18220.00 22770.00 3365.00 5405.00 9438.00 14692.50 18130.00 9044.90 10115.00 17366.90 22867.00 5013.00 14521.50 5805 .00 9459 .00 13550.00 16220.00 4235.00 8526.00 13002.00 8176.00 16335.00 7587.50 13667.50 19750.00 4014.00 7508.00 13773.00 18238.00 3650.00 6918.50 10250.00 4053.50 4704 .00 7453 .00 8506.00 9075.00 12759.00 4037.50 6901.00 8077.50 FREOUENCY 120 120 120 120 120 120 120 120 120 120 120 120 120 120 120 120 120 120 120 120 120 120 120 120 120 120 120 120 120 120 120 120 120 120 120 120 120 120 120 120 120 120 120 120 120 RPM IOC 576 576 576 576 576 576 576 576 576 576 576 576 576 576 576 576 576 576 576 576 576 576 576 576 576 576 576 576 576 576 576 576 576 576 576 576 576 576 576 576 576 576 576 576 576 USSR MOSKVA MOLODEZHNA YA KHAVAROVSK SAN FRANCISCO PEARL HARBOUR NORFOLK MOBILE LA JOLLA KODIAK GUAM BOSTON USA CITY ANKARA COUNTRY TURKEY CALLSIGN YMA5 YMA5 NIK NIK NMF NMF NPN NPN NPN NPN NPN NPN NOJ NOJ WWD WWD WLO WLO WLO NAM NAM NAM NAM NPM NPM NPM NPM NPM NPM NMC NMC NMC NMC RHO RHB RHO RHO RUZU RUZU RUZU RUZU 3377 .00 6790.00 3502.00 12750.00 3242.50 7530.00 4975 .00 7894.00 10255.00 15990.00 19860.00 22910.00 4298.00 8459.00 8646.10 17410.60 6852.00 9157.50 11145.00 3357.00 8080.00 10865.00 16410.00 2122.00 4855.00 8494.00 9396.00 14826.00 21837 .00 4346.00 8682.00 12730.00 17151.20 19275.00 7475.00 9230.00 14737.00 9280.00 15830.00 17660.00 18490.00 2815.00 5355.00 7750.00 FREOUENCY 90 90 120 120 120 120 120 120 120 120 120 120 120 120 12.0 120 120 120 120 120 120 120 120 120 120 120 120 120 120 120 120 120 120 60 90 120 60 120 120 120 120 60 90 120 RPM IOC 288 288 576 576 576 576 576 576 576 576 576 576 576 576 576 576 576 576 576 576 576 576 576 576 576 576 576 576 576 576 576 576 576 576 288 576 576 576 576 576 576 576 288 576 ~ ~ z z z <:!) z z <:!) c.. c.. <( z z <:!) Ill"' cr.i ...J ...J <( u ...J ...J <( u z ~ c.. ~ c.. Ill ...J ...J 0 (,) 0 N ..... cr.i cr.i II: 1- N ..... ► :c a. ◄ II: Ill"' (/) I- c.. II: <.O z U") c., O: :E ◄ ::) c., Cl L.lJ L.lJ r-- ...J ...J <( u ~ c.. ...J 0 N ..... Cl L.lJ w c.. (/) <.O r-- LI") Ill (,) - Z ◄ (,) Ill ◄-◄ :c a. z II:"' II:::) 0 g:c ◄ II: c., z Ill 0 t-m Cl) II: ◄ Ill (/) (/) (/) (/) (/) :::> :::> :::> :::> :::> ..... 0 0 0 0 0 5 :::> :::> :::> :::> :::> 1:11 ~~~ ~~ .... I- I- I- I- I- :z::zzzzz ~◄ ~:c uooooo (,) u,uuuuu -I -I -I >- 0 fil N N::t!::t!::t! ◄ m: >cc ◄ .... :::r: :::r:-'"'-'"'-'"' > =◄ z ◄ Ill ~ z z <:!) cr.i z 0 cr.i (/) ~ z An example of a weather fa x picture received on HF from AXM (Canberra) is shown in Fig.5 . (/) <( C: Further reading .,...r--C'lNC:00 ...J ...J <( (1) ARRL Handbook, 1989; (2) Weather Satellite Handbook, Ralph E. Taggart; (3) Schedule of Australian Meteorological Radfax Broadcasts (available from the Director of Meteorology, Bureau of Meteorology, Attention SRCM, GPO Box 1289K, Melbourne, Vic. 3000). a=C'lC:OOC'lM ._ ~ r-,... .,- .,..... N u (/) ::::::,-'"'-'"'u;O-=t LI") '<t LI") <.O <.O za. u Q these satellites use the same picture format, making reception of these pictures relatively easy. Fig.1 shows a list of current satellites and their frequencies while Fig.2 shows a list of current HF transmissions. The National Oceanic and Atmospheric Administration [NOAA) Weather Service broadcasts numerous weather satellite photos taken by GOES (Geostationary Environmental Satellite) spacecraft as shown in Fig.3. Also, the US Naval Oceanography Centre transmits weather information by HF fa x for use by US naval vessels and stations and for use by the US Military Sealift Command. Although designed for navy use, these charts are also of interest to private and commercial marine interests (see Fig.4). t- Fig.5 (below): this weather fax was received on HF from the Bureau of Meteorolgy in Canberra. It is just one of many different weather maps transmitted by the Bureau. ...J ...J <( u ~ c.. ...J 0 N ..... Cl LJ.J L.lJ c.. (/) <.O >- ...J r-- LI") z 0 >...J (/) z 0 z 0 (/) cr.i :::> :::> (/) ...J ...J -:::>:::>~ z 0 (/) N SQ ~ N (/) z LI") LI")<( (/) '<t '<t C: zMMt<CNN ~g:oo~ ::::::, t-t-<:!) u Q e~U")U")~ (/) ~5,2:;:!::;:!:<( z 0 u,zoo □ cr.i (/) N ~ :::r: (/) fil::t!::t!~~ ~..:::.:::..:::.:::0.,..- <( ...,."Q"cor,.....,a=M<.ONI"- ...J ...J <( >c::::1- <.O N N M u; ... ~co.,......,- z C: t- JULY 1990 91