Public Address Systems

128 Pages·2003·14.91 MB·English

You don't just buy a great computer. ..
... You buy the company that stands behind it!
NOTEBOOK NOTEBOOK
. 386 sx 25 486 sx 25
$2,380 $3,190
• 386 SX 25 MHz System Board • 486 SX 25 MHz System Board
•4MBRAM •4MBRAM
• 1.4 MB Floppy Disk Drive • 1.4 MB Floppy Disk Drive
• 80 MB Hard Disk Drive • 120 MB Hard Disk Drive
BUDGET PAK VALUE PAK
) 386 sx 33 486 DLC 33
$1,800 $2,500
• 386 SX 33 MHz System Board • 486 Cyrix 33 MHz System Board
• 2 MB RAM expandable to 1 6 MB • 4 MB RAM expandable to 32MB
• 1.2 or 1.4 MB Floppy Disk Drive • 1.2 and 1.4 MB Floppy Disk Drive
• 85 MB IDE Hard Disk Drive • 128 MB IDE Hard Disk Drive
UPGRADE SPECIAL • 14" SVGA Colour Monitor & Card • 14" SVGA Colour Monitor &C ard
• MS Windows & Works • MS Windows & Works
• IBM NLQ Printer • IBM NLQ Printer
386 SX 33 MHz System Board $245
386 DX 40 MHz System Board $388 SUPER PAK SMART PAK ''>
486 DLC 33 MHz System Board $668 3&6 DX 40 486 DX/2 50
486 DX 33 MHz System Board $1,188
$1,950 $3,399
486 DX 50 MHz System Board $1,499
70 nsec. IM SIMM RAM (per MB) $60
• 386 DX 40 MHz System Board • 486 DX/2 50 MHz System Board
70 nsec. 4M SIMM RAM (per MB) $205
• 4 MB RAM expandable to 32 MB • 4 MB RAM expandable to 32 MB
Floppy Disk Drive (1.2 or 1.4) $100
• 1.2 and 1.4 MB Floppy Disk Drive • 1.2 and 1.4 MB Floppy Disk Drive
170 MB Hard Disk $576
• 128 MB IDE Hard Disk Drive • 210 MB IDE Hard Disk Drive
210 MB Hard Disk Drive $738 • Trident 1 MB SVGA Card • Trident 1 MB SVGA Card
Sony CD ROM Kit $639 •Samsung 14" SVGA Colour Monitor • Samsung 14" SVGA Colour Monitor
Sound Blaster & CD ROM Pack $750
IBM NLQ Printer $239 PR(O PAK POWER PAK
HP 500C Deskjet Colour Printer $1,180 48f> DX 33 486 DX 50
HP 2P Laser Printer $1,399
$3,575 $4,680
Trident lMB Super VGA Card $110
Tseng T4000 32 K Colour VGA Card $180
• Intel 486 DX 33 MHz System Board • Intel DX 50 MHz System Board
Paradise Windows Fast Card $245
• 4 MB RAM expandable to 32 MB • 8 MB RAM expandable to 32 MB
NEC 3FG Monitor & SVGA Card $990 • 1.2 and 1.4 MB Floppy Disk Drive • 1.2 and 1.4 MB Floppy Disk Drive
MS Works for Windows $119 • 170 MB IDE Hard Disk Drive • 210 MB IDE Hard Disk Drive
MS Windows 3.1 $99 •Tseng lMB SVGA Card • Tseng 1 MB 32K Colour SVGA Card
WordPerfect 5.1 DOS/Windows $250 • NEC Multisync 3FG Colour Monitor •NEC Multisync 4FG Colour Monitor
• All prices includes sales tax.
We stand behind you ...
We stand behind our computers.
HEAD OFFICE: BRANCHES:
A VO Electronic Systems Pty Ltd A VO Computers (North Sydney) A VO Computers (Chatswood)
188 -192 Pacific Highway 99 Mount Street 22 Thomas Street
(Cnr Bellvue Ave) (Cnr Walker St) CHA TSWOOD NSW 2067
ST LEON ARDS NSW 2065 Shop 8, Mount Street Plaza TEL: [phone] AVO COMPUTERS f
TEL: [phone] NORTH SYDNEY NSW 2060 FAX: [phone]
(;real·
FAX: [phone] TEL: [phone] ~t
READER INFO NO. 1 FAX: [phone]
Volume 55, No.2
WITH
w:li
February 1993
AUSTRALIA'S LARGEST SELLING ELECTRONICS MAGAZINE - ESTABLISHED IN 1922
The 81 satellite story
Video and Audio
6 PAY-TV ALREADY HERE: NIGHTLY, IN JAPANESE TV Oceania
16 WHAT'S NEW IN VIDEO & AUDIO The latest products ...
18 THE CHALLIS REPORT: Sony's NT-1 'Scoopman' digital microrecorder
Features
10 THE LONG MARCH OF OPTUS' B1 SATELLITE Background story ...
24 A $40 WEATHER SATELLITE RECEIVER! How to adapt a cheap set
28 WHEN I THINK BACK... PA systems 2-SA's pioneer Laurie Simon
32 EARLY HISTORY OF AUSTRALIA'S RADAR -2 Air warning radar
The new Optus B-series satellites are 56 MOFFAT'S MADHOUSE Singing the praises of duct tape, in any colour!
now in orbit, signalling the dawn of
a new era for Australia's broadcast Projects and Technical
ing and communications. Kate
Doolan tells the story of how the Bl
satellite was built and launched, in 46 THE SERVICEMAN Dried up electro's, dud parts & mods by dingalings
her story starting on page 10. 64 CIRCUIT & DESIGN IDEAS 110 for Amiga, audio test oscillator & more
68 IMPROVED 50MHZ FREQUENCY COUNTER Compact, low in cost
Not for the majority. .. 78 LOW COST DSO ADAPTOR FOR PC'S Use your PC as a scope ...
90 VINTAGE RADIO Displaying your vintage equipment
93 EXPERIMENTING WITH ELECTRONICS A Morse code 'intercom'
100 AUTOMOTIVE ELECTRONICS Automotive data scanners - 2
Professional Electronics
106 , NEWS HIGHLIGHTS lnmarsat plans global satellite hand phones by 2000
110 H·P'S SCANJET Hp FLATBED SCANNER New low cost 300dpi unit
114 SOLID STATE UPDATE NiCad charger IC, 16-bit audio chip set
116 8051 MICROCONTROLLER PROTOTYPING BOARD Make your own
122 NEW PRODUCTS Voltage reference standard, new power resistor line
124 SILICON VALLEY NEWSLETTER Machine zaps toxic waste
Sydney-based TV Oceania is already 126 COMPUTER NEWS & NEW PRODUCTS New 21" monitor from Philips
broadcasting Pay-TV every night
but not for most of us. It's in Japan Columns and Comments
ese ,for tourists and visiting business
people. Barrie Smith explains, in his
story starting on page 6. 4 LETTERS TO THE EDITOR Wesat reception, satellite power query
5 EDITORIAL VIEWPOINT Dawn of a new era in communications ...
40 FORUM Fluoro lamp safety and fancy audio cables both revisited
58 SHORTWAVE LISTENING Seventy years of broadcasting celebrated
On the cover 96 INFORMATION CENTRE Computers, UHF reception and more
104 AMATEUR RADIO NEWS New FM handheldsfrom Kenwood
Our new 50MHz counter project is
the latest addition to our 'cheap but
Departments
useful' instrument family. Essentially
an update of our very popular 1988
design, it will make most commonly
85 . BOOK REVIEWS 130 DIRECTORY OF SUPPLIERS
needed measurements yet should
102 EA CROSSWORD 130 ADVERTISING INDEX '
only cost around $100. See page 68.
103 MARKETPLACE 44 NOTES AND ERRATA
(Photo by Greg McBean)
ELECTRONICS Australia, February 1993 3
LETTERS TO
MANAGING EDn'OR
Jamieson Rowe, BA., B.SC., SMIREE, VK2ZLO
FE'ATURES EDITOR
Peter Murtagh, B.SC, Dip.Ed.
TECHNICAL EDITOR THE EDITOR
Rob Evans, CET (RMIT)
TECHNICAL CONSULTANT
Peter Phillips, B.Ed., Dip Ed., ECC
CONTRIBUTORS
Neville Williams, RREE, VK2XV
Jim Lawler, MTETIA
WESAT reception specifically designed only as a tuneable
Arthur Cushen, MBE
Tom Moffat, VK7TM IF for GMS reception on 1691MHz
I am writing to you regarding some
Peter Lankshear using a suitable downconverter.
Louis Chafffs comments you made in your review
Major Al Younger (USAR, Ret.) in EA September 1992 of the SA1FAX As a guide my own APT receiver has
SECRETARY the following measured specifications:
software.
Ana Marfa Zamora sensitivity, 0.2uV for 12dB Sinad;
DRAFTING Your comment that "The WESAT sig
bandwidth, 50kHz at -3dB points; and
Karen Rowlands nals use a deviation of around 30kHz" is
COVER DESIGNER incorrect. The satellites transmit a devia signal/noise 42dB at 1u V .
Clive Davis Please do not take these comments as
tion of +/-17kHz of the carrier (this
PRODUCTION a 'rubbishing' of Tom's efforts, quite the
Patrice Wohlnlck, Mal Burgess varies about one or two kHz with in
reverse, in fact, as a keen 'home brewer'
ADVERTISING PRODUCTION dividual satellites). GMS-4 (1691MHz)
Anthony Macarounas on the other hand transmits with a myself any articles on this interesting
CIRCUIATION MANAGER hobby are most welcome.
deviation of +/-126kHz.
Michael Prior Peter Williamson, VK4AWP
PU BUSHER To reproduce the full greyscale of the
Albany Creek, Qld.
Michael Hannan image a receiver bandwidth of 50kHz is
Comment: I stand corrected, Peter!
ADVERTISING MANAGER ideal, as it also takes into account the
Selwyn Sayers [phone]
+/-3/4kHz of doppler shift that is ex
HEAD OFFICE -EDn'ORIAL Dick needs book
180 Bourke Road, Alexandria, NSW 2015 perienced during the satellite pass.
P.O. Box 199, Alexandria 2015 Your comment that wide-band FM Would your readers be able to help me
FRaexa nduemr Sbeerrv: i(c0e2s): 3P5h3on 0e6 (1032 ) 353 0620 receivers can be used successfully is not finda book?
Subscriptions enquiries: phone [phone] true in most cases. Certainly under ideal In the mid-1950's, as a young radio
Book Shop enquiries: phone [phone] signal conditions some useful pictures enthusiast eagerly reading every issue of
MINETLEBROSTUARTNEE A: D5V0E4R PTrIiSncINeGs HOigFhFwICaEy,S N oble Park, will be obtained, but in the main the Radio & Hobbies, I built a radio which
Vic 3174. Phone [phone]. results will be very disappointing. was described in an English book. If I
Fax: [phone], Nikki Roche. The 150kHz bandwidth of these remember correctly, the circuit consisted
BRISBANE: 26 Chermslde Street, Newstead,
Qld 4006. Phone: [phone]. receivers results in noisy images at best. of two battery valves (could it have been
Fax: [phone], Ken Yates. My tests on an AOR receiver indicated a IS4 and 3S4?) regenerative radio,
ADEIAIDE: 98 Jervofs Street, Torrensville, SA
5031. Phone: [phone], around 30uV of signal was necessary to complete with Reinartz coil.
Fax: [phone], Sue Bowshall. obtain a useful signal, certainly not a The distinguishing part of the radio
PERTH: Allen & Associates, 54 Havelock Street,
West Perth, WA 6005. Phone: [phone], fully quieting signal. A YUPITERU was that it was built on a wooden chas
Fax [phone], Tony Allen. scanner was somewhat better at 0.7uV sis. The book was hardcover, published
1U2N INTEorDw KicIhN GStDreOeMt,: LJoonhdno Fna, iErfCax4 A& 1SBoHn.s (Aust), for a similar signal quality. in the United Kingdom in early 1950.
Phone: [phone], Fax: [phone] A correctly designed receiver with a I can remember well that the radio ran
A2S10IA1:, Hceaaudswewaya yM Beadyia C Seenrtvreic, e1s5 L-2td3, SRuogoamr 50kHz bandwidth will achieve this order on an expensive 67.5 volt battery which
Street, Hong Kong. Phone: [phone], of signal quality around 0.3uV, an im took me six weeks on my paper run to
Fax: [phone], Adrian Batten. provement of 20dB over the AOR pay for. I would love to purchase a copy
ELECTRONICS AUSTRALIA Is published by
Federal Publishing Company, which is owned receiver. of this book for old time sake.
by General Newspapers Ply Ltd. If you are still in doubt, have a close If any of your readers could help, I
A.C.N. 000 117 322
Double Bay Newspapers Ply Ltd. look at Tom Moffat's two pictures, al would be delighted. By the way, EA is
A.C.N. 000 237 598 though they appear on the surface to an excellent publication - I still read
Aan.Cd. NB.r e0h0m8e 6r 2F9ai r7fa6x7 P ly Ltd. be OK, they do in fact contain quite every issue!
180 Bourke Road, Alexandria, NSW 2015. a lot of noise, a pity, as the Dick Smith,
Copyright© 1989 by Federal Publishing METEOR picture would have been a Australian Geographic,
Company, Sydney. All rights reserved.
No part of this publication may be reproduced ripper on a 50kHz receiver! POBox321,
in any way without written permission from the Tom must also be very lucky to be in a Terrey Hills, NSW 2084
Publisher or the Managing Editor.
Typeset and printed by Hannanprint, 140 low noise area; compare this with your
Bourke Road, Alexandria, NSW for Federal own experiences. Adding a pre-amplifier Satellite power
Publishing Company.
Distributed by Newsagents Direct Distribution will only degrade the already poor over I read with interest the article in
Ply Ltd, 150 Bourke Road, Alexandria, NSW load cross and inter-modulation perfor December, about the tethered satellite
2015. [phone].
The Australian Publication emblem on the front mance of these receivers. Post detection experiment. This experiment was in part
cover of this magazine is there to proudly signify filtering will only achieve a minimal im to find out if electrical power could be
that the editorial content in this publication is
largely produced and edited In Australia, and provement in signal quality. developed by a long conductor cutting
that most of the advertisements herein are the From the above, your comments in the the earth's magnetic field. The result
products and services available within Australia.
SA1FAX article that my GMS receiver would be a DC voltage between op
ISSN 1036-0212
*Recommended and maximum Australian retail which has a typical bandwidth of posite ends of the conductor.
price. 280kHz at -3dB is suitable for APT The piece of information the article
reception is definitely not true. It was did not convey was where is the return
4 ELECTRONICS Australia, February 1993
----
-~·---------·
path for the electrical power so
generated? The diagram of the power
generating cable showed only one single EDITORIAL
conductor.
To further add to the mystery, even if
there was a return conductor, would it
not generate the same voltage, and in so VIEWPOINT
doing cancel out the voltage in the other
conductor? One of the cables would
have to be magnetically shielded ..
Obviously, this power generating sys
tem works, but on the information given
I cannot understand how.
All the best at Electronics Australia.
Dawn of a new era in
Will McGhie,
Lesmurdie, WA. communications and broadcasting
Comment: As we understand it, Will, the
return path is via the ionised plasma As I write this, Australia has clearly just entered a new era in satellite
which surrounds both the satellite and the communications and broadcasting. A couple of days ago on December 16, the
tether line. The Shuttle had to have an first of Optus Communications' new B-series satellites took over from the
'ion gun' unit, to effectively make contact original Aussat Al, which after seven years of service had reached the end of
with the plasma. its operational life. The changeover took place very smoothly, with a disrup
To be honest, though, we're not too sure tion to all services of less than 40 seconds - surely remarkable, considering
how this whole system could be used to the complex technology involved.
generate power - like all such systems, Last night I was able to check some of the 'fortuitous' PAL TV signals
all it does is convert mechanical energy coming from the new B 1 high-power transponders, and the improvement over
(the satellite's orbital kinetic energy) into the old low-power transponders is very noticeable. Vrrtually gone is the
electrical energy. No energy comes from remaining 'sparkle' noise on saturated colours, and the signal-to-noise ratio on
the magnetic field or plasma ... the sound channels is greatly improved. This is with a 1.8m dish and 1.0SdB
LNB, by the way. I can quite believe that the professional broadcasting and
AAPRA and BayCom
communications users must be delighted with the enhanced performance and
I enclose a copy of the fax of the letter expanded capacity. This is quite apart from the new 150W L-band transponder
to you from Johannes Kneip of the Bay on B1 , which now provides the potential for a dramatic improvement in
Com team in Germany, which I trust you Australia's mobile radio communications.
have received direct by mail. With the B2 satellite due to be launched before Chrisunas, by the time you
This is to clarify that AAPRA referred read this Australia should have all of the primary technology in place for a
to in item 1, is the Australian Amateur national satellite TV and radio broadcasting system, as well as a truly up-to
Packet Radio Association. date communications network. So when you consider the enormous potential
AAPRA can supply a registered copy also rapidly developing in the area of photonics and optical fibre distribution,
of the BayCom program Version 1.Sa on we really are entering an extremely exciting period of change in both com
5-1/4" or 3-1{2" disk, complete with munications and broadcasting.
Austtalian produced 48-page manual, Happily in this month's issue we have an interesting background story by
for A$25.00, postage and packing in Kate Doolan, on the development of the new Hughes HS-601 'next
cluded. generation' satellites that are being used by Optus for its B series. I'm sure
AAPRA can also supply the BayCom you'll find it as interesting as I did. There's also an intriguing story from
designed and built modem inside a DB9 Barrie Smith, explaining that while most of us will still have to wait for years
plug, complete with program disk and to get Pay TV, our Japanese community and tourists already have such a
manual as above, for A$180.00, postage service in operation every nighL ..
and packing included. Other features in the issue include the second of Colin Mac Kinnon 's articles
Any profits from the sale of equip on the pioneering days of radar in Australia, and some new project designs
ment are used to help clubs establish net that I think you'll find of considerable interest - including a low-cost adaptor
work nodes (ROSE). Over $20,000 has which converts your PC into a digital sampling scope, and an updated version
been contributed to date. of our very popular economy SOMHz counter. ·
John Barrett, VK2AUQ, for AAPRA This month's review from Louis Challis is of Sony's new and incredibly
59 Westbrook Avenue, tiny digital dictation recorder, the NT-1. This is the one we featured on the
Wahroonga, NSW. 2076 cover last month, you may recall, and Louis says that despite his experience
with digital audio technology in general, he was almost 'blown away' by the
performance delivered by this latest microscopic marvel.
DROP US A LINE! By the way if you were one of those who were disappointed to find that we
hadn't been able to include this review in last month's issue, please accept my
Feel free to send us a letter to the
apologies. Events conspired to prevent us including the review in the issue
Editor. If it's clearly expressed and
which carried the cover picture - sorry!
on a topic of interest, chances are
Jim Rowe
we'll publish it - but we reserve
the right to edit those that are over
long or potentially libellous.
ELECTRONICS Australia, February 1993 5
PAY·TV ALREADY HERE:
NIGHTLY, IN JAPANESE
The rest of us may still be wondering when or even if we're likely to get the opportunity to
watch Pay-TV, but Australia already has two such systems operating. The lesser known of
these is TV Oceania, which broadcasts to Eastern Australia's Japanese community and
tourists for three hours each evening.
by BARRIE SMITH
Some Australians still have difficulty 'Coming soon' potentially lucrative technology door -
with the apparent 'Japanisation' of is TV Oceania.
Our PM declared on TV one Sunday
Australia most evident in TVO began as the brainchild of a pair
morning that we would be watching
Queensland, with Brisbane street names of engineering consultants, Hanle Prinz
Pay-TV as of some time in 1993. Then,
carrying Kanji along with the English and Michael Thompson, who could see a
as is often the way with such ad hoc
script. And, of course we all 'know' that niche marlcet servicing the Japanese
declarations, the decision was reversed
99.99% of all hotels in that state are community in Australia. The pair had
barely weeks later. Since then,
Japanese-owned. Or so it seems ... the RF knowledge and experience, but
Australia's Pay-TV future seems to have
Less evident is the number of not the funds to get it all together.
been debated almost weekly.
Australian businesses now operating However, commercial support was
But few people realise that we already
which rely solely upon Japanese found and the business slowly moved
have Pay-TV - in limited fonn - via
patronage. One of these is TV Oceania, off. Prinz and Thompson are no longer
Sky Channel, which delivers wall-to
operating with a staff of less than 20, connected with the operation, which is
wall sport to the nation's hotels, TAB
from compact premises beside Sydney's now majority owned by Japan Travel
agencies and clubs. And, besides Sky
Darling Harbour development. Bureau - along with a holding by Japan
Channel - with its foot also in the
Air Lines.
Operating since early 1991, the station
currently compiles three hours per night
of Japanese programming and delivers a
24-hour Teletext service in Kanji.
Three areas of the Japanese com
munity are serviced: the tourist hotel
trade, a corporate audience and (as of
October 1992) domestic installations in
Japanese-occupied homes.
The company's satellite coverage
spreads from Cape York to Adelaide. It
was expected the service would be
linked with 15 - 16,000 rooms in 36
hotels by the end of last year, covering
80% of Japanese tourist arrivals.
TVO's general manager John Martin
explained how the hotel system works:
"The guest pays $10 for a 24-hour
cycle - billed to their room account.
This gives them access to two full-time
channels in the Japanese language, as
well as the nonnally available English
language channels."
A major slice of the $10 is TVO's,
with the hotel receiving a small propor
tion for their support and service
provision.
Residential installations are arranged
by the company contracting direct with
the viewer: "We install the equipment.
They pay an initial joining fee, a deposit
TV Oceania's ID, as transmitted to 36 hotels In Austral/a. Domestic Installations
were due to begin in October 1992. and a monthly programming charge.
6 ELECTRONICS Australia, February 1993
-\
The original NTSC signal Is converted to PAL with a Tetra
Mastercontrolat1VOceanla.ASonyswltcherplusBetacam P165 standards converter and remains In PAL (via
SP editing system are ussd In programme compilation. Thompson-CSF VldeoCrypt) for uplinking to sate/lites.
· We've done it this way because most of From here, it travels on a terrestrial vice - also on A3. Both the Teletext
the Japanese viewers would be on 2-3 feed to Channel lO's control room, then and TV are on the same satellite for the
year conttacts." back out to Belrose. From here it is NE beam."
turned around and comes in here at
Twisted path TVO, bouncing off an unmanned NTSCto PAL
Although TVO is operational for only repeater en route-because we're in a When the Tokyo feed arrives at
three hours each evening, when the bit of a hole here in the city of Sydney." TVO, a Tetta P165 standards con
second hand reaches 7pm nerves are a "We switch it into our programme verter transforms the NTSC 4.2.2 stand
little strung in Master Control. At this - because we have leads into and ard to PAL, which remains in PAL
precise moment the station switches out of the 'live' news cross. Then it's from that point on.
from an ID graphic to the 'live' news back out to Belrose and up onto the The signal is then passed through the
feed, arriving from NHK's studios in two AUSSAT Austtalian satellite usual waveform monitoring functions
Tokyo. There are many chances of an feeds. We've got it located on Al and delivered to a Sony vision mixer.
'outage', due to the circuitous path the satellite, the other is on A3 satellite - Externally sourced, but locally as
NHK signal follows. two different transponders and not sembled tape is integrated with the
According to TVO's chief engineer even on the same satellite!" Tokyo programming.
Peter Pratt, the original satellite hookup "Basically, that same live news Programming includes variety, quiz
was direct with Tokyo: "NHK were programme, apart from all the terrestrial shows, music, plus financial material
uplinking a dedicated feed to us via a links, goes onto the Pacific Ocean satel such as the Nikkei business review. To
Pacific Ocean satellite, but this was a lite twice, onto a domestic satellite in the this is added a topical Sydney studio
very expensive operation to have a news review.
dedicated transponder direct from Leaving the vision mixer, the sig
Tokyo to here." nal is passed through a Thomson-CSP
However, it was then found that NHK VuieoCrypt encryption system, PC
were also sending the same programme driven. A scrambled picture leaves
into the USA, where service similar to the Sydney facility.
TVO's was operating. A continual data feed arrives via a
This feed was being turned around in phone line from Kyodo news service.
the States and redirected back out into Input to a PC's word processor, this is
Bangkok: "So we thought, why don't printed out and sub-edited.
we get onto the Thailand feed and try Local content - news, information,
and bring that in here. But then getting theatre programmes, etc - is added and
that across the Pacific and finding a the signal, as Teletext, goes back out on
spare transponder and someone who one of the audio carriers on · the
The news from NHK In Tokyo, as
would carry it for us became quite a microwave path, then goes up on the
received 'live' In Sydney. It travels over
challenge, calling for much negotia a particularly circuitous route. FM-squared system on the satellite, al
tion." lowing a data stream to be sent on a nar
Pratt recounted the circuitous path USA and then does two different satel row bandwidth that runs 24 hours.
NHK's nightly news talces: "Leaving lites in Australia So the poor old news Says Pratt: "It took a while to get
Tokyo it goes via the Pacific Ocean service does a lot of ttavellingl" the software running for the word .
satellite into the USA, then does a "There are three transponders being processor, because Japanese Kanji text
domestic satellite hop across the used: Al - TV only, which goes to SE characters total around 3000. This
country, is picked up in Santa Paula in Austtalia; A3 has the Teletext data number does not fit nicely into the
Los Angeles, back onto another Pacific which gets married to the TV 256-character ASCII code, so we use
Ocean transponder and down into OTC programme in SE Australia. a UNIX-based computer and· 16-bit
at Oxford Falls in Sydney. There's also the NE Australian TV ser- processor. Even the character ROM
ELECTRONICS Australia, February 1993 7
READER INFO NO. 2
Pay-TV already here: Nightly, in Japanese
SOLAR PANEL LASER GUN
BARGAIN SIGHT
~
~
A 5mW gunsi1;1ht at an
amorphous solar panels. unbeatable price.
Two of these in series $279
make a great 12V battery
maintainer/ charger. Item No. 0108
Incredible pricing. Includes one "Free" rifle
!1:'1Q or pistol mount.
ea or 10 for $85.
fte~ No. 0130 ELECTRIC
FENCE KlT
~gn~:~3J~f;~~ig~~n~~~il0
It features very low power
consumption, a solar
charging/regulating and
indicating circuit, and it can
be easily solar powered.
The PCB (Screened and
solder masked) and all
Used air cooled ARGON components kit will cost
laser heads. that produce under $50
a BLUE beam! Power out
put is in the 30·100mW INDUCTIVE
range. Limited stock, at a
ction of their real value: PROXIMITY
~ 600-800 ...
'S'W'ITC\HEiS
or the Argon head only.
We also provide a circuit
for a simple power supply.
Item No. 0109
A local news reader gives regular bulletins for Interpolation Into the NHK service.
These industrial quality
daentde cntoonrs-f ewrirlol udse tmecett afelsrr oaut s in the receiver had to be specially Martin considers it a 'wonderful
close proximity. Some are developed. situation' where you have legislation,
DC powered (10-30VO,
some are AC powered "What the tourist has is a 24-hour ser with Royal assent, that is in place, but
(Mains), and all will switch
Two used 3mW Siemens loads directly. All have a vice on his TV set The timetable is refers in part to Section 7 (re Pay-TV)
tHueb'eNse, avnisdib olen ere odf loausre er ffi tinhtroe ec iwrciureit rfyo:r Tcwonon sfo~r1 -thien g made up of the live TV that we present - which as yet isn't in the Act!
cient 12V universal laser supply, and one for switch each evening, recorded in the hotel for Normal national services are provided
supply kits. ing the load. LIMITED
$129 $QQ QUANTITIES at a small subsequent replay. This is switched into for within the legislation, along with
LTheIt esme cENoon.d d t?uiboes xi.s a fraction of t$he2ir8 re al price: a number of tapes dedicated to the community broadcasting and subscrip
Bonus t1il9l 9en3d o nolfy J. anuary VISIBLE LASER region. For example, in North tion services: "You can have narrow
PROJECTION DIODE Queensland we've got a small presenta casting and broadcasting subscription
BARGAIN tion: welcome to Australia; this is the services. The main Pay-TY service is
Brand new 5mW-670nM currency, etc. That drops in five or six going to fall into the category of sub
laser diode, plus a collimat· times during the day. Plus there's the scription broadcasting. That's the bit
ing lens, plus driver kit,
plus, hardware, plus Teletext information." which is heatedly debated."
instructions.
$89 "Because the Teletext and TV ser Martin's operation falls into a
Main body has a diameter Item No. 0164 vices were operating on separate satel 'narrowcasting' category, because of
DIVERGING
olofn tg1. 7Tmhme wahnodl eis a ts0s7emmmbl y lites, we had to develop a dual satellite their subscription basis. The constraints
LENS SPECIAL
can be easily unscrewed reception system. So we have con in terms of ownership and control of
to obtain three very large e
~~:er~~o~:s~~sf;~f .· .. ......, figured a special dish which covers the programming standards are the basic
the c~eapest large magni- two satellites simultaneously - the two ones - no cigarette advertising, no R
fier or projection system? • •
Experim$e2nt8er s delight at - being set on 160° (Al) and 164° (A3) rated material. As Martin understands
ONLY •dAi• vh•ei;gr"ghi "nqg"u 'a( b-lietya ·lmas -eexr pbaenadme r) geostationary orbits." the Act, 'narrow' applies if you are
LASER glass lens, mounted on an The signal path presents the main limited by one of a number of points:
. ,P:INT. ..1• ; ••• :2. . 6mDmiommuen.n tiUsnisgoe ns srct: r te2ow5 e sxx pp2ra5on vxdi d tehde. porpoegraratimonmael diisf figcouilntyg. Nthoroteusg Ph rastot: m"Tanhye gprroougprainmgm; inpgro gtarargmemtteindg tod irae cpteadrt ictou laar
laser beam for Holography. links on the way here - if it stops, if special interest; or reception in a limited
Special Effects, or one of
l~~ ~~:n;f:s~~'.:~.tror there's an outage anywhere, we have to number of locations. As he sees it, his
High quality pen sized Surveying and Bar Code find the reason and prevent it happening company's activities clearly fall within
SmW laser diode pointer Reading.
for teachers, doctors, etc. SPECIAL again. Quite often, in our master control this meaning.
On Special g;1gg $5.00 ea. room, we 'hot switch' as the clock hits
Item No. Oji1il01. ....." '. the 7pm mark." Future expansion?
It is arguable whether Pay-TV will be
'Narrowcast' licence
the bonanz.a some commentators
Australia's broadcasting legislation foresee. From a national point of view it
has escaped comprehensive revision is difficult to contend with the view that
since the early 1950's. However a new a local operator, possessing the opera
Act did pass through both houses of Par tional track record that TY Oceania ob
liament in 1992 - except for a section viously has achieved, should be allowed
+
relating to Pay-TV. to participate in a wider coverage.
8 ELECTRONICS Australia, February 1993

10 ELECTRONICS Australia, February 1993