<\/p>\n
I cannot remember exactly when it was, but I remember the day well\u00d6 I was at work early making sure that everything was operating properly, and my cellphone rings. Caller ID says phone number is not available, which is unusual, but not too so. Answering the phone the guy on the other end said he was calling from the USA, and asked if I wanted to work on the Olympics, doing APRS?<\/p>\n
<\/p>\n
The guy on the phone was a Ham from central Pensylvania, and
\nworked for Winemiller Communications who I found out later was the principal RF
\ncontractor for the Sydney Olympic Broadcasting Organisation. I aggreed to get
\nwhatever maps I had available together and copied to CD-ROM for Jeff Winemiller
\nwhen he visited Sydney a few weeks later. This article is all about what
\nhappened next\u00d6.<\/p>\n
<\/p>\n
Overview<\/p>\n
<\/p>\n
Sydney has a very poor RF environment \u00f1 there are no great
\ntall buildings that you can see from everywhere to point a microwave receiver
\nat. From most parts of Sydney you cannot see the CBD nor the mountains to the
\nwest from ground level. This causes lots of problems if you need to get video
\nsignals from street level back to a control room. Although the AMP tower (Centerpoint)
\nlooks tall from inner Sydney, when you go move towards Olympic Park, it
\ndisappears.<\/p>\n
<\/p>\n
For an event such as the marathon, you could always use
\ncables, but can you imagine laying the video cables for the entire 42 Km of the
\nMarathon? This left one option, wireless video cameras with some sort of a
\nrepeater system to get the microwave signals out to the rest of the world.<\/p>\n
<\/p>\n
It would have been possible to put cranes up throughout the
\ncity with microwave receivers but this would not have looked very good. It also
\nassumed that there would be line of site to the crane which would not have been
\npossible all the time.<\/p>\n
<\/p>\n
So the only way to get line of site for the microwave signal
\nwas to have a repeater that somehow followed camera vehicles as they went along
\nthe course. The only solution that worked technically was to have helicopters
\nfollow the vehicles as they followed the course.<\/p>\n
<\/p>\n
<\/p>\n
<\/p>\n
Three motorcycles and a lead vehicle providing live video
\nand audio from the course.\u2020 With microwave antennas pointed straight up from
\nground level, a helicopter would need to be well under one KM from the vehicle
\nit was receiving in order to get a decent signal.<\/p>\n
<\/p>\n
But there is no way that you could keep the four vehicles so
\nclose together during a race so having a single helicopter was not really an
\noption. There was also the problem of signals potentially interfereing with
\neach other in the receiver, and also what happens when the helicopter needs to
\nrefuel.<\/p>\n
<\/p>\n
More than one helicopter was needed, but how many more? It
\nturned out that the best solution was to have a helicopter assigned to each
\nvehicle. That way when a helicopter needed to refuel two vehicles would need to
\nstay close together, sharing the one helicopter until the other one returned.<\/p>\n
<\/p>\n
<\/p>\n
<\/p>\n
<\/p>\n
<\/p>\n
<\/p>\n
<\/p>\n
Auburn Control<\/p>\n
<\/p>\n
The Auburn control room was one of the hidden sites during
\nthe Olympics. Security was almost totally non-existent and parking was usually
\nplentiful. There were certainly no security checkpoints or parking
\nrestrictions. Located on the top of the old nurses home at Auburn Hospital,
\nno-one knew we were there and we liked it that way.<\/p>\n
<\/p>\n
During the games the building had been housing health care
\nworkers for the games, and many of these had the night of the closing off work.
\nThat evening many of them stumbled across our control room on their way to the
\nroof to see the fireworks. To say that they were stunned was an understatement
\nwhen they saw what had been going under their noses during the games.<\/p>\n
<\/p>\n
Not that we had not caused problems of our own. So that we
\ncould safely have our people working on the roof, we got scaffolding put up,
\nincluding new stairs. This scaffolding could be seen from the Olympic Stadium
\nit was so visible. But the problem with the scaffolding is that it tends not to
\ncreate problems when you build it around a TV antenna, which is of course what
\nhad been done.<\/p>\n
<\/p>\n
On the day of the opening ceremony, someone worked out that
\nall except for one TV channel worked \u00f1 the one channel that did not work was
\nthe Olympic broadcaster, Channel 7. So with just hours to spare we move the
\nantenna for them, and even replace the co-ax which looked as if it had been put
\nin with when the building was built in the early 1960\u00eds. [As an aside, there is
\nevidence to suggest that the bricks for this building came from the State Brick
\nWorks that were located in the middle of the Sydney Olympic Park site]<\/p>\n
<\/p>\n
<\/p>\n
Our control room was actually located in a plant room above <\/p>\n Each rack contained at least one video monitor \u00f1 I think we <\/p>\n There were a couple of telephones in the control room, along <\/p>\n The first number was an emergency number in case of Hijack <\/p>\n The second number was far more useful \u00f1 it was the number of <\/p>\n <\/p>\n <\/p>\n <\/p>\n Fibre Optics<\/p>\n <\/p>\n As I mentioned before, nestled between the two water tanks <\/p>\n In the rack, CODEC\u00eds convereted from PAL Video to Fibre or <\/p>\n The fibres came from each of the receive sites (Uni of NSW, <\/p>\n <\/p>\n <\/p>\n <\/p>\n Video Switching<\/p>\n <\/p>\n Having 2 or 3 different receive sites means that decisions <\/p>\n To do the switching, each switcher was given a Jaycar <\/p>\n [Insert Kolm cartoon]<\/p>\n <\/p>\n During some races such as race walking or Road Cycling where <\/p>\n <\/p>\n Quality Control and Video Coloring<\/p>\n <\/p>\n One of the hidden jobs of the Auburn control room was to <\/p>\n We had one transmitter on Waverly Tower east of the Sydney <\/p>\n At times the video coloring dropped out, but this usually <\/p>\n Whenever the colouring control did drop out it was my job to <\/p>\n <\/p>\n 110V & Electrical Safety<\/p>\n <\/p>\n The electrical environment was quite bizzare. With an american <\/p>\n However we did discover the problems with importing <\/p>\n Working in dual 110\/240V created some problems even for <\/p>\n My boss actually blew up a couple of laptops thanks to the <\/p>\n <\/p>\n One of the more bizzare problems was when we were powering <\/p>\n The guy plugged the transformer in, and the equipment did <\/p>\n That same morning the roof of the control room with all the <\/p>\n <\/p>\n <\/p>\n <\/p>\n <\/p>\n <\/p>\n <\/p>\n <\/p>\n UNSW and Auburn Rooftops<\/p>\n <\/p>\n With microwave signals, line of sight is a must. The problem <\/p>\n Each site had six microwave dishes on tripods, tracked by <\/p>\n Each dish needed to be put away each night, and assembled <\/p>\n Once they obtained an Esky, and borrowed an old car radio <\/p>\n <\/p>\n <\/p>\n <\/p>\n <\/p>\n <\/p>\n City Wide Repeater system.<\/p>\n <\/p>\n For any large event, good communications is essential\u00d6 And <\/p>\n Five channels were used in the 500 MHz band connected to a <\/p>\n This is not the full story though \u00f1 During races we had the <\/p>\n The worst job during the whole Olympics must do to Casey <\/p>\n <\/p>\n <\/p>\n <\/p>\n <\/p>\n The Manly Ferry<\/p>\n <\/p>\n One of the technical successes of the whole Olympics must be <\/p>\n The things that make Sydney so beautiful are what causes all <\/p>\n This all called for a unique engineering solution. French <\/p>\n The COFDM system was installed with an Omni-directional <\/p>\n <\/p>\n <\/p>\n The receive site at Neilson Park was more interesting <\/p>\n Over the path of the ferry, there are a few places where the <\/p>\n Watching the coverage of the Torch Relay just before the <\/p>\n [It is amusing to write that the ferry that beached itself <\/p>\n <\/p>\n <\/p>\n <\/p>\n <\/p>\n <\/p>\n <\/p>\n <\/p>\n <\/p>\n International Broadcast Centre<\/p>\n <\/p>\n The International Broadcast Centre was where most of the <\/p>\n <\/p>\n At the centre of the IBC was SoboTech, where all\u2020 the <\/p>\n All the video signals inside the IBC were PAL, even for the <\/p>\n <\/p>\n <\/p>\n <\/p>\n <\/p>\n #########ADD MORE<\/p>\n <\/p>\n <\/p>\n <\/p>\n The control room was basically a switching station<\/p>\n <\/p>\n <\/p>\n <\/p>\n <\/p>\n <\/p>\n <\/p>\n Security<\/p>\n <\/p>\n Security at the Olympics was a pain at times. They relied on <\/p>\n After going through security he and having his bag searched <\/p>\n Another time I was taking some equipment into the Stadium, <\/p>\n <\/p>\n Car searches were equally as thourough. They had glove box <\/p>\n Also cars were only searched if there was someone available <\/p>\n <\/p>\n <\/p>\n <\/p>\n <\/p>\n <\/p>\n Cars\u00d6<\/p>\n <\/p>\n I did not know this, but in NSW there is a registration \u2020\u2020\u2020\u2020\u2020\u2020\u2020\u2020\u2020\u2020\u2020 3 Outside Broadcast vans \u00f1 About the side of \u2020\u2020\u2020\u2020\u2020\u2020\u2020\u2020\u2020\u2020\u2020 4 motorcycles.<\/p>\n \u2020\u2020\u2020\u2020\u2020\u2020\u2020\u2020\u2020\u2020\u2020 1 bike trailer for the four bikes.<\/p>\n <\/p>\n I was going to say that they were all driving around Sydney <\/p>\n The three vans were all left hand drive of course. This made <\/p>\n <\/p>\n <\/p>\n <\/p>\n <\/p>\n <\/p>\n APRS – Air Traffic Control<\/p>\n <\/p>\n As mentioned before the reason I was actually there was so <\/p>\n <\/p>\n <\/p>\n I guess the most important part of the whole exercise was <\/p>\n GPS (or Global Positioning System) receivers are used to <\/p>\n <\/p>\n The TNC\u00eds were programmed to transmit position information <\/p>\n One of the problems in this type of situation is that many <\/p>\n Placing the transmissions into timeslots took some planning, <\/p>\n As I mentioned before, all the transmitters were operating <\/p>\n We chose to use a digipeater since it could operate in <\/p>\n So we turned one of the helicopters into a digipeater. This <\/p>\n For obvious reasons 5 other helicopters and the light plane <\/p>\n There were times that the relay helicopter was not available <\/p>\n I am told that the light plane used APRS in an rather <\/p>\n The pilot had a hard job, because he needed to stay within <\/p>\n But the light plane was essential to the success of the APRS in the Sydney 2000 Olympics I cannot remember exactly when it was, but I remember the day well\u00d6 I was at work early making sure that everything was operating properly, and my cellphone rings. Caller ID says phone …<\/p>\n
\nthe 6th<\/sup> floor of the building. The plant room contained two large
\ncopper water tanks that were used to maintain mains pressure water in the
\nbuilding. These water tanks used up about a half of the room, and we had the
\nother half. The entire room was about 5m x 5m. Not very large when you consider
\nthat the usable space was about 2.5m x 5m, and in that space we placed about
\nten 19\u00ee rack cabinets, and had another one positioned between the two water
\ntanks. This room also contained a PC for my work, and up to about seven people
\nworking, with spectators occasionally.<\/p>\n
\nhad about 31 video monitors in\u2020 this small room which required some squeezing
\nin\u00d6 Many of the racks contained monitors four high. This created a video wall
\nwhich would have been impressive if you could see it all. But as I mentioned
\nbefore size was limited. Most of the monitors were on the 4m wall, with about
\n0.5m between the backs of the monitors and the wall. When you realize that most
\nmonitors are about 0.5m deep themselves, the 2.5m usable space becomes 1.5m.
\nThis does not leave much room for people wanting to watch the screens. It was
\noften so cramped that anyone moving required 3 or 4 other people to move to
\nallow you get out of the room.<\/p>\n
\nwith three links direct to the repeater system. The telephones were used
\nextensively, but there were two main phone numbers next to the main phone.<\/p>\n
\nor Air Piracy of an aircraft \u00f1 which was particularly absurd considering that
\nthe aircraft would only have a pilot and a technian in them, and could not
\nreally seat a hijacker. Besides which, the technician worked for us, and it was
\nunlikely that the pilot would hijack is own plane. Still, we kept the number
\nthere just in case\u00d6<\/p>\n
\nthe local Pizza Hut. They got to know use well. The best order was for 9 large
\nand extra large pizzas, and about 16 liters of softdrink for lunch on the day
\nof the Men\u00eds cycling. The order was so large they let me use the back entrance
\nto the Pizza Hut normally reserved for their delivery people.<\/p>\n
\nwas a 19\u00ee rack. This rack had 23 fibre optic cables coming in from various
\nsites thanks to our friends in Telstra, as well as one underworked UPS in case
\nwe ever lost power. Each fibre contained a 230 Mbit\/Sec data stream of
\nuncompressed PAL video. When all links were operating this equated to about 5 Gbits\/second
\nthrough the Auburn control room alone. When you consider that Packet Radio
\noperates at 1200 bits\/sec and Ethernet is about 10 Mbit\/Sec you realize that
\nthis is a lot of data.<\/p>\n
\nFibre to PAL depending on the direction of the link. The CODEC\u00eds also
\ntransmitted full stereo audio, 4 switch inputs and an RS-232 link allowing
\nalmost any possible signal to be moved around.<\/p>\n
\nand Equestrian), and sent data a feed back to each site, and also sent video
\nback to the International broadcast centre. In addition the IBC (International
\nBroadcast Centre) also sent back video to us from the Manly Ferry, and program
\nvideo. There were also backup links direct to the IBC from the Equestrian
\nCentre and UNSW in case there was a major breakdown at Auburn.<\/p>\n
\nneed to be made on which signal to use. Whilst it might be possible to automate
\nthe switching, we just threw people at the job during the Olympics. This
\nallowed us to anticipate what would provide the best signal, providing a better
\nsignal most of the time.<\/p>\n
\nproject box with 4 or 6 buttons in two columns. Each column selected a
\ndifferent camera, and each row selected a receive site. The switches were set
\nout so that they could be held by both hands, and use their thumbs to press the
\nswitches \u00f1 much like playing some video games \u00f1 but in this case with only
\nabout 1 million of our closest friends watching in Australia, and probably over
\na billion throughout the world.<\/p>\n
\nthe course was fairly small video switching became more of an exercise of
\ntrying to keep interested since the pictures were always so good from the
\nreceive sites. During the Marathon and Triathlon more effort was required
\nmaking the job more enjoyable [albeit a bit more stressful].<\/p>\n
\nmaintain all the cameras so that they looked the same. This was not as easy as
\nit sounds. All cameras are different and react differently to different light
\nlevels. To fix this problem, remote control of the iris and coloring of the
\ncamera is possible thanks to a cute packet radio transmitter from Total RF.
\nThis unit used a 500 MHz band radio signal running at two watts broadcast to
\nthe motorcycles where the radio signal was decoded and fed into the camera.<\/p>\n
\nCBD connected by a modem, and another transmitter on the roof of Auburn. The
\nantenna at auburn was a simple 6 element Yagi cable tied to a paper so that we
\ncould change direction easily. We would have liked to get an Omni, but at that
\nfrequency the Yagi was easier to buy, and provided some gain if we needed it.<\/p>\n
\ndid not last very long. It meant that all the camera operators needed to worry
\nabout was zoom and focus \u00f1 which was good since they were from Spain and did
\nnot know English. We were not so fortunate with the Helicopter video cameras,
\nas the operators needed to manually adjusted the coloring \u00f1 and once again they
\ndid not know English leading to a new kind of Chinese whispers during Olympic
\nevents.<\/p>\n
\njump a fence on the roof of the hospital and more the direction the antenna was
\npointed to.<\/p>\n
\ncompany came all the 110V equipment, whilst the Australian gear all operated on
\n240V. In the Auburn control room were about six 2000 watt auto-transformers to
\nchange the voltage. They were large, and came with metal handles for carrying.<\/p>\n
\nequipment that was not Australian Made only after almost blowing up some leased
\nline modems. We discovered that the handles would actually become a shorted
\nturn when they touched and spikes were getting into the equipment. This
\nequipment should never have been allowed into Australia.<\/p>\n
\npeople like me who should have known better \u00f1 I got one computer out of it\u00eds
\nbox, plugged it in, and BANG. Power supply set for 110V. Fine, only the PSU
\ndestroyed, and we had a spare one in another computer where the shipping
\ncompany destroyed the motherboard.<\/p>\n
\nuse of UPS\u00ed and differing grounds. Don\u00edt ask me how, but somehow they managed
\nto get the laptop to float above ground, and blew the laptop when they plugged
\nin to the serial port.<\/p>\n
\nup the control room one morning. One of our team went behind the racks to the
\npower points to plug in the voltage conversion transformers that we had
\ndisconnected the previous night, in case of surge or an electrical storm.<\/p>\n
\nnot work. He looked at the transformer, and decided that it had failed and was
\nabout to replace it when I had a look. The first thing I did was plug the
\ntransformer in elsewhere, and it worked. Then I put it back in the power point
\nand turned it on, and everything was fine. After that I proceeded to tell him
\nthat these things work better when they are turned on. He did not even think to
\nturn the power point on, since they do not have switches in the USA.<\/p>\n
\nmicrowave dishes and personel experienced an unnerving freak of nature. As we
\nwere waiting for a rehearsal in severe fog there was an almighty bang and flash
\non the roof. Static electricity had built up and had suddenly discharged. This
\ncaused the people on the roof quite some shock \u00f1 and they quickly left the roof
\nfor close to an hour when some of the fog had lifted. No damage was done to
\nwhich we were all grateful.<\/p>\n
\ncomes that a helicopter flying at 500 ft is obscured by some Sydney buildings
\nwhen they are flying near the City and the receiver site is at Auburn. But as
\nthe \u00ebchopper gets close to the UNSW the coverage at Auburn improves. However as
\nit gets very close, the beam width of the receiving antenna is so narrow that
\nit is effectively impossible to get a good signal. For these reasons we had two
\nmain receive sites for microwave signals.<\/p>\n
\nhand. Three dishes were for motorcycles, one for the lead vehicle, and the
\nremaining two dishes were for two helicopter video cameras. Each dish had
\ntunable microwave receiver in the 1.9 GHz to 2.5 GHz band and an LCD monitor so
\nthat they could see the picture they were receiving. When the helicopters were
\non the other side of the city, they normally had an easy job, but had to
\nmaintain concentration when the helicopter was close.<\/p>\n
\nagain each morning. But once the equipment was set up, the trackers would
\nnormally have up to an hour before a rehearsal, and after the rehearsal often
\nan hour or two before the race started, meaning that they got to spend a lot of
\ntime on the roof sunbathing. Some of our team got quite respectable suntans \u00f1
\nsomething that would have been impossible back home in the USA.<\/p>\n
\nthe conditions on the rooftops became quite civilized.<\/p>\n
\nyou could say that the Olympics is the Ultimate large event. With about 40
\npeople working for the company, and more than that out in the field needing to
\nhear instructions from the director required a good repeater system was used.<\/p>\n
\nvoting repeater system. A Voting repeater system has a number of different
\nreceiver location, and repeats the one with the best signal. In our case we set
\nup receiver sites in North Sydney on the Hyundi Building, in eastern Sydney on
\nthe UNSW, and at Auburn near Sydney Olympic Park. Our transmitter was located
\non Waverly Tower also in eastern Sydney. All the sites were connected by
\ntelecom \u00eb4 wire\u00ed circuits providing excellent repeater coverage from the 5 Watt
\nIcom HT\u00eds that we used.<\/p>\n
\nrepeater running full time. In addition the director and our control room had
\ndirect access through the \u00eb4 wire\u00ed circuit so that we didn\u00edt actually need a HT
\nto transmit, and we could operate full duplex, even if those with HT\u00eds couldn\u00edt.<\/p>\n
\n[#insert Call] who looked after the repeater at the Waverly telephone exchange.
\nNot only was Casey effectively alone much of the time, he did not even have a
\nTV set to watch the Olympics, nor was there anyone to relieve him for lunch.
\nSince he was baby-sitting the repeater he did not actually have much to do
\neither. About half way through the games things improved when he got his VK ham
\nlicense and was able to access the Waverly Amateur Radio Society repeater,
\ndirect from the console.<\/p>\n
\nthe live video link from the Manly to Circular Quay ferry. During the 8 Km
\njourney, the ferry travels an \u00ebL\u00ed shaped path through some of the harshest
\nmicrowave territory in the country.<\/p>\n
\nthe problems, The Sydney Harbor bridge causes reflections, the Sydney Opera
\nHouse stops a single receive site access to the entire path of the ferry with
\nthe entire terrain just adding to the problems.<\/p>\n
\ncompany Sagem has recently released a COFDM transmitter which was put to good
\nuse. COFDM, or Coded Orthogonal Frequency Division Multiplexing is a digital
\ntransmission standard soon to be used in most of the civilised world. The COFDM
\nsystem digitizes the video into an MPEG data stream and then creates an analog
\nmicrowave signal using 2000 carriers and modems. Error Correction and Coding is
\nused to reduce the number of errors on the received signal.<\/p>\n
\nmicrowave antenna on the top of the mast on the Manly Ferry. The antenna was
\nconnected to a transmitter in the body of the ferry. Since the power in the
\nferry was variable, and often disconnected we installed a UPS to protect the
\nsensitive computing equipment. At the front of the ferry a remote controllable
\ncamera was mounted in a waterproof housing. The camera was controlled by a UHF
\nradio link to the microwave receive site, and then connected to the IBC<\/p>\n
\nbecause of the it\u00eds unconventional antennas. Being at the middle of the L meant
\nthat the antennas needed be open well over 90 degrees, whilst maintaining reasonble
\ngain. The solution was to use three cresent dishes. The signal from each dish
\nwas fed into an LNA, and then into a combiner. Finally the signal was fed into
\nthe decoder, where the signal appears out about 1 \u03a9 seconds later as a perfect
\nPAL video signal.<\/p>\n
\npicture dropped out, but in most cases the picture was what could only be
\ndescribed as perfect. The picture was even fantastic where the ferry was moored
\nat Circular Quay and the signal was bounced off the Harbor Bridge.<\/p>\n
\nopening where the Flame was on the Collaroy ferry showed just how good a job we
\nhad done. Channel 7 had a camera on the ferry with a microwave uplink, although
\nthey did not have a good signal path to their helicopter, so the signal kept
\ndropping out. Whenever this happened, the producer switched to our video camera
\nproviding the perfect pictures.<\/p>\n
\nas this article was being written was the same one as used for the torch during
\nthe Olympics.]<\/p>\n
\n<\/span><\/p>\n
\nworlds electronic media congregated to bring all the signals in from all the
\nvenues, process them and distribute them world wide. As you can imagine with so
\nmany events the IBC was a huge undertaking. The main building of the IBC was
\nabout 200m by 330m, and contained about 25 different roads \u00f1 each named in some
\nuniqely australian way [Such as The Dogs Leg, Lamington Drive, Wedgie Way, The
\nMain Drag etc]<\/p>\n
\nsignals came in for distribution throughout the IBC. SoboTech had about 400
\nvideo and audio signals coming in through fibre optic cables. Each signal was
\nthen displayed on it\u00eds own monitor on a 400 TV video wall. Then the signals
\nwere distributed to each of the broadcasters either as an Analog or a Digital
\nsignal [About 50% of users used digital].<\/p>\n
\ncountries that used NTSC or SECAM. The only exception was Japanese TV who also
\nhad some HDTV cameras.<\/p>\n
\nyour honesty. One afternoon after work I went around Sydney Olympic Park with
\none of our team members, into the area outside the security zone. He was
\nwearing a pocket knife on his belt which he needed for work. On returning
\nthough security he had placed the pocket knife in his bag, and left the holder
\non his belt.<\/p>\n
\nthey asked if he had a pocket knife on is belt. He said no, and they let him thorugh.
\nIt was in his bag.<\/p>\n
\nand was walking thorugh a checkpount. I had 2 backpacks, a 1.5m antenna, 2U
\nrack mount case and some other equipment. I was loaded. I took all this off,
\nand failed the metal detector test. They then put the wand over me and I
\npassed. They declined to search my bags at that point, and asked if I was
\ncarrying any \u00ebExplosives, firearms or knives\u00ed. Since I had my butane soldering
\niron with canister of butane I said yes, to which they asked \u00ebdo you have any
\nchemical or nuclear weapons\u00ed. The obvious answer was yes, and I went through.<\/p>\n
\nWednesdays where they would search every glovebox in cars coming into the Olympic
\nPark. Thursdays it was boots, Tuesdays it was engine compartments etc. The only
\nway to get out of a search was if the compartment was sealed with a sticker at
\ndeparture \u00f1 but I saw vans who\u00eds back door was sealed, but where there was easy
\naccess from the front door.<\/p>\n
\nto search the car \u00f1 no search if the searches were searching someone else.<\/p>\n
\nlabel that you can get if you are an overseas visitor and you want to drive
\nyour own car around. The registration label states that it is registered as an
\nunregistered vehicle, sort of a contradiction. And to get it the vehicle must
\nbe insured. Why an I telling you this. Well, we imported [by sea] a few
\nvehicles for the games, all from the west coast of the USA. The tally\u00d6<\/p>\n
\nFord Econovans. Each with a retractable 50 foot microwave antenna<\/p>\n
\nwith Pensylvania number plates, but that is not quite right. Seems that someone
\nstole the plates of two of them during shipping so they went round without
\nplates at all. At one stage I tried to get a copy of the NSW Police Report
\nconcerning stolen USA plates so that the Pensylvania DMV would replace them and
\nship them to Sydney. Lets just say that we placed this in the Too Hard basket.<\/p>\n
\nit fun driving around Sydney for our people. One of our team, obviously an
\narmchair lawyer, decided that it was not legal to be driving around with no
\nsteering wheel on the right hand side \u00f1 so he bought one. Technically it was a
\nsteering wheel cover, but it was the right shape at least \u00f1 and attached it
\nwith Gaffer Tape. Now they were legal.<\/p>\n
\nthat I could monitor the locations of motorcycles, lead vehicle and helicopters.
\nActually I was also monitoring the position of the Auburn control room, but
\nluckily that was not moving.<\/p>\n
\nthe work I was doing with APRS. APRS, or the Automatic Position Reporting
\nSystem. APRS is a technology designed to collect and distribute information on
\nthe position of objects. Normally these objects are cars or houses, but could
\nbe anything from border crossings in Bosnia, to sheep on a New Zealand farm, or
\nin my case video cameras.<\/p>\n
\nwork out where the object is, although this is not always the case. The GPS
\nreceivers are connected to Packet Radio TNC\u00eds and then connected to radios
\ncreating a network of stations.<\/p>\n
\nevery 20 seconds. This was not ideal, but it was good enough. The problem was
\nthat we had a lot of stations, and if we had chosen more than 20 second
\ntransmissions, they would not have all fitted in.<\/p>\n
\nof the stations will want to transmit their data at the same time. This would
\nhave been a real problem since our transmitters were all low power, and they
\ncould not always hear each other. The solution was to schedule every
\ntransmission on the network. This is actually built into the TNC\u00eds which helped
\nme considerably. To make sure that all the TNC\u00eds used the same timeslot, the
\ninternal software synchronizes the transmission to the highly accurate time
\nfrom the GPS receiver.<\/p>\n
\nbut it was worth it.<\/p>\n
\non low power \u00f1 only 5 watts on the 500 MHz band. There was no way a 5 watt
\ntransmitter on the wrong side of the Sydney CBD was ever going to get data back
\nto the Auburn receive site. The two options were to use a second receive site,
\nlike with the repeater system, or use a repeater.<\/p>\n
\nhalf-duplex mode. Normally digipeaters are fixed objects on a building
\nsomewhere. In our case setting the equipment up on a high building would have
\nrequired too much work, and would not guarantee the performance of the whole
\nsystem.<\/p>\n
\nhad the effect of putting the digipeater on a 1000-1400 foot mast, easily
\nhigher than all the buildings in Sydney. The five ground units were then
\nprogrammed to use the helicopter when it was available [In-Air refueling of
\nHelicopters was not considered viable].<\/p>\n
\ndid not need to use the repeater as they could be heard direct, just as the
\nrepeater could be used direct. What made this solution even better was that we
\nhad APRS equipment in all the helicopters so all I needed to do was to
\nreprogram the TNC to turn it into a digipeater. [The reason we did not use the
\nlight plane for a digipeater was that it was there for emergency use during
\nimportant races, meaning that there were times it was not available. It was
\nalso the only aircraft that had laptops meaning that we could reprogram it to\u2020
\nbecome a digipeater in case of emergency anyway]<\/p>\n
\nbecause of refueling. At these times we generally lost the position of the
\nmotorcycles, although we would occasionally get the position updates through
\nwith reflections.<\/p>\n
\ninteresting way. As soon as they got to altitude of about 14,000 feet the pilot
\nwould cover all the windows with cardboard and fly by instruments. He would use
\na laptop in the plane to tell him where to fly, and where he was. Of course he
\nused his other instruments too, but APRS told him where he was needed.<\/p>\n
\nabout 2Km of all the motorcycles, and at the same time circle doing flat turns,
\nwhich I am told is a rather nasty way to fly requiring a lot of concentration.<\/p>\n
\ngames because for the start of the women\u00eds marathon it was providing the only
\npictures from the ground because the helicopters could not take off because of
\nfog.<\/p>\n","protected":false},"excerpt":{"rendered":"