HAM APRS Tracker – Byonics to the Rescue – sort of.

APRS Tracker Issues – an Amusing Response.

In Australia to use an APRS tracker you will need a “full call sign” for an amateur radio operator. A foundation or other license is not good enough. We use these trackers by always ensuring that we are not putting it on to a commercial payload, or that the commercial payload agrees to space in their payload for community experiments. We always use 2 trackers and they simply may be a pair of SpOT trackers or a spot tracker and APRS. At times we have even used 2 APRS trackers with different SSIDs (identifying codes)

My High Altitude Balloon (HAB) work just got made a little easier. My old trackers were all starting to fail. I just took delivery from Byonics of one of their MT2000 HAM radio APRS trackers. This is only for licensed Ham Radio operators and it is a sweet device for its size. It can output over 2W of power and has a full transceiver on board. It is easily configurable and runs off 5v to 12v. I think power output is a bit less than 500mw at 5V. It is as light at anything and easily programmable as I also bought the USB cable – a 9 pin D connector for RS232 slips over the end and I will solder it in place. I usually slip a VHF antenna right on the end (red cover cap) and I will solder the special GPS receiver in place on the board. There is still a connector on the GPS unit. It should be noted that these GPS units are configured to work above 60,000 ft as most GPS stop there. Don’t try using the GPS in your phone for tracking on a balloon!

Hey, before I go too far with the Tracker, here is a video from one of our flights. Made for MYOB, it shows the quality of our work. This payload was extreme and we built it on the spot from a wooden frame prepared the night before:

I suggest that you click full screen to get the real impact of this video! In fact go to YouTube and it is really HD

https://www.youtube.com/watch?v=tvWjNYja8xA

The payload had 8 cameras 3 power banks, 6 voltage regulators, 1 actuator and 2 trackers. One camera was a Fly360 x 240 camera.

Back to the tracker:

https://www.byonics.com/mt-2000

Here is what they say:

The Micro­Trak 2000 (MT2K) is a frequency agile, 2 Watt, programmable miniature APRS (Automatic Position Reporting System) transmitter utilizing a TinyTrak3 controller chip and is capable of operating from 144 to 148 MHz.

Just plug in a GPS receiver, such as the Byonics GPS5, add a SMA antenna, and start tracking!

  • No need to tie up an expensive radio for APRS tracking
  • Simple 2 wire GPS connection
  • Supports all the latest Byonics TinyTrak3 features.

Note the special GPS block in the picture below. That is what to look for:

Byonics MT2000 APRS Tracker

APRS Tracker Failures – Why?

We could not get an answer to this question because we are simply too good at recovering the units.

We insulate them with bubble wrap, but the super low temperatures in the jet stream (-50ish C) seem to affect the devices over time. Several have died. When I asked Byonics the question as to why, it appears no one can answer me. It seems customers always loses their trackers and we seem to only notice this problem because we have never lost a payload and keep using them. It looks like they only last about 10 flights with super low temperatures and super low pressure. If this works as expected, then I will have to order more. Everyone else loses them by this time. I expect it is a temperature issue and we will try and compensate of update our units after about 7 flights.

Configuring your APRS Tracker

The important parameters to specify for preconfiguration when ordering from Australia for a MT2000 balloon tracker are:

Your HAM radio Call Sign with the appropriate SSID. Mine is VK2URB-11

The Digi Repeater parameters:  WIDE 1-1

The Australian APRS frequency:  145.175MHz

Transmit interval:  every 20 seconds – no receiver check

Symbol:  /o balloon

Any appropriate text:  mine is “UpLift Balloon”. Keep it short as it makes the transmit packet bigger.

Watch out – other countries use different frequencies

Our Growing Tracking Ability

Our Pajero Tracking VehicleJan 2016

Pajero Tracking Vehicle Update

So lets look at what my son, Jason (14), and I have done and are doing about our tracking vehicle. We will have more, but we are planning on at least having our 4WD SUV ready for anything that is headed our way, but tracking is all important. Note that this tracking article appeared on our Project ThunderStruck website some months ago. read more

Lessons from UpLift-20

Weather balloon burst

What a burst weather balloon should do! Disintegrate

UpLift-20 Lessons Learned the Hard Way

Jason, our 12 year old pilot for Project ThunderStruck is no stranger to having to prepare for the worst and it is what we do every time we send up a payload on a high altitude balloon. Our last flight of a balloon into the stratosphere was a case of just that. Two failures. One on launch and the second on decent. Each problem would be enough to cause most balloon payloads to be lost, but as part of our preparations, we carried two trackers for the one flight. This was a flight in preparation for our project and we are testing. We have had to cover our payload in the video. Our apologies.

Below: An artist’s view of the ThunderStruck aircraft under a zero pressure balloon (more on that another time) at 40km altitude. You may have guessed, I am the artist….. Note that on the ThunderStruck event, we will not be using weather balloons so there will be no unexpected explosions.

Balloon Flight with ThunderStruck

Failure One

The first failure was totally invisible to us. A massive downdraft. The first that we have ever encountered. Uplift-1, our first flight, started in an updraft and it rose at an incredible rate for the first kilometre. In the video below, you can hear me make the comment that there did not appear to be the lift that we knew we had because we had used scales to measure the lift. We could not feel the downdraft pushing the balloon down 15 metres above our heads. I mistakenly thought my lack of “feel” was because of the others also holding the payload. We released the payload and balloon and then our hopes sank as the payload only lifted slowly and then sank back to the ground. We ran to catch it, but it rose again and caught on the edge of the eve of the roof of a nearby wheat silo. It stayed there for only 2 minutes, but it felt like an eternity before it released. It rose quickly as calculated, but one tracker had had its GPS unit disconnected and the other had its antenna twisted 90 degrees effectively lowering the power considerably. None the less we could still track the flight – mostly.

One tracker disabled, but still sending its ID at full power, The other effectively made to look low power. Those GoPro cameras are great. hundred of metres above the ground you can hear (faintly) people talking and a dog barking! They make great gear.

Failure Two

The weather balloons are meant to explode and disintegrate. This one did not. The entire balloon, well over 1Kg fell into the parachute and tangled itself in the chute, effectively making the mass look like more like a tangled flag than a parachute. It slowed the payload in the thick air, but the fall from its maximum height was rapid and the entire fall from 30km only took 15 minutes. This was an average speed of 120kph. Given that the payload probably hit the ground at 30 to 40kph, the initial speed was probably close to 400kph in the thin upper air.

With the tracker only giving us effectively a poor signal, the last track that we received in one of the vehicles headed to the landing site was 2 km above the ground making the landing site potentially one square kilometre.  We also fond out later that the second tracker was never going to give us a signal, because the impact had caused a battery to eject from its holder. We only had one ID every 20 seconds and no GPS location! We used a directional antenna to lead us to the payload, but it was a slow and painful task.

The video below shows the impact and the wooden spars breaking. The camera continued to record! Nothing like a good wiring system to ensure that power kept flowing from the external battery. I did not mention that we use external batteries. The GoPro’s batteries, even with the additional power pack, just do not last for the entire flight if it goes over 2.5 hours and especially if it is taking both videos and stills – The new GoPros are amazing, but need more power for High Altitude Balloon (HAB) flights.

Initially the video above shows the incredible stability of our payload at 30km altitude. The Balloon explodes at the 30 second mark and then plummets and spins at a sickening rate of a  couple of times a second with the disabled chute causing the spin.  At 1 minute 45 seconds, we cut to an altitude of about 3km and it took 3 minutes to hit the ground at 60kph. At the 4:45 mark, the payload hits and spars shatter. The camera keeps recording. By the way, the big tree lined road is the Mid Western Highway. The payload was kind enough to land in a sheep paddock beside the main road. You can’t ask for better.

The Lesson

The lesson here is that if it can go wrong, it will go wrong. Yes, we have recovered every payload that we have sent up, but good preparations both in the payload design and build is important as are the preparations for recovery on the ground. We even carry poles to remove the payload from trees. We can manage 14 metre trees. After that we will have to look at other methods.

Our preparations will be backup, backup and more backup. Redundancy rules over weight considerations where possible. Systems will be over-engineered and more care will be taken than what appears necessary. Project ThunderStruck will fly while the world watches. Delays will be unacceptable. This was UpLift-20 and again we have 100% successful recovery rate. @0 flown and 20 recovered. As our flights become more aligned to the actual shape of the ThunderStruck aircraft, speeds will dramatically increase on decent and the videos will have way more interesting stuff to show, but these lessons were there to remind us not to get complacent.

Balloon flight Payload Recovered

High Altitude Balloon Success. Payload Recovered.Andy PS1 Preparing to fly

Jason and I went to Deniliquin NSW (Australia) to help a good friend, Andy from Melbourne, launch and recover a high altitude balloon / payload. I am part of Team Stellar going for the Google Lunar X-Prize (GLXP). I am in charge of Communications, Tracking and Data. Jason (11) is their Australian Student Representative. Jason and I have launched and recovered 16 payloads to date and assisted with others and we love High Altitude Balloons (HABs).

I brought my fellow Team Stellar member, Tim Blaxland and his son Rhys (9) along for the experience. Tim is Stellar’s chief of Navigation. The launch was at Deniliquin and we traveled part of the way there on Friday and the rest early on Saturday morning to be there for a 9:30 start. It was an 8 hour drive and we intended to do another 8 hours back later on Saturday after we recovered the payload.

Fellow HAB enthusiast Todd Hampson also traveled from Sydney in his own vehicle. it was great that we all arrived at the designated point in a timely fashion and started the final preparations for launch. Other than Tim and Reece, we all have Amateur Radio licenses and on this flight we would have 2m APRS tracking system. See earlier posts about APRS. In addition there was also RTTY on UHF. The RTTY system s available for non amateur radio hobbyists to use.

Andy had a video camera camera hooked up to a Raspberry Pi unit. Its job was to break up the video into smaller packets of data and send it along with the RTTY GPS information. The pictures are then sent to a server on the internet and the packets reassembled into a complete picture if all of the packets are received. The transmitter is very low powered and many people set up their equipment to help receive and download the images. Below is an image from the flight. The grey strips are missing packets that no one managed to receive successfully.

Note that at this time of the year, the wheat and other crops  have been harvested and the temperatures are in the 40C range at times. With little rain, the fields are a brown cover. The dark areas are either farms with crops still growing or trees around the rivers that flow through the region.

Andy PS1 flight Deniliquin NSW

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

The photo is only from a low resolution camera but the payload also carried a GoPro that took photos. The top image is a small section from the flight camera while it was on the ground.

Here are the details that Andy distributed before the flight:

FYI, there will be a HAB launch from Deniliquin NSW this weekend, Sat 8th Feb 2014 at 11am EST.

 Payloads will be:
– SSDV RTTY 300baud, 450Hz shift, 8N1, 434.650Mhz (+- drift) USB, 25mW quarter-wave antenna
– APRS 1200b 145.175Mhz 100mW with dipole antenna
– Cutdown RTTY 100baud, 450Hz shift, 8N1, 432.220Mhz (+- drift) USB, 25mW downlink, quarter-wave antenna.
RTTY tracking will be on spacenear.us, callsigns PS and PSPI
SSDV images will be uploaded to ssdv.habhub.org, callsign PSPI
APRS tracking will be on aprs.fi, callsign VK3YT-11

The temperature was 42C / 108F for much of the day and UV protection was essential. Recovery was easy, so we did not have an issue with tracking through the forests looking for the payload.

The flight lasted around 2hrs 50mins, reached max altitude of 36,789m / 120,699ft / 22.9 miles  before the balloon burst and landed in a paddock.

The following images were transmitted whilst in flight:

2014-02-08--01-11-07-PSPI-8C9 2014-02-08--01-43-42-PSPI-8CB2014-02-08--02-04-48-PSPI-8CC

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

2014-02-08--02-44-03-PSPI-8CE

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

The last image was taken close to maximum altitude.

GoPro3 images in the next post. Below, the flight path from left to right. The tropospheric winds (Jet Stream) where pushing the balloon to the eastand the stratospheric winds blew us west . When the balloon burst, the winds eventually took us east again as we passed through the Jetstream.

The Flight PS1 Map The Flight PS1 terrain

 

Balon Stellar Stratosfera 30Km

Stellar Balloon flight to the stratosphere in CroatiaJason & Robert to Fly Balloons (HAB) in Croatia.

by Robert Brand

As many will know, I am the Director of Spacecraft Communications, Navigation and Data for Team Stellar and Jason is Stellar’s Australian Student Representative.

Jason and I also hold a world record for launching and recovering High Altitude Balloons (HABs). We have launched and recovered 16 so far and you can’t get better than 100% success. Mind you, much of that is attributed to us researching and finding a fantastic launch and recovery area with HAM radio APRS coverage (one of our tracking systems), flat and clear land with little water and good mobile telephone coverage and good access roads to farming and grazing land.

Croatia is a very different place. Our Team Stellar Croatian associates have told us that part of our recovery team will be Aplinists, capable of hiking in snow and ice to recover any balloon that lands high up on a mountain!

So why is Stellar launching these flights?

STEM EDUCATION:

Balon Stellar Stratosfera 30Km

Basically we will be carrying experiments from schools all over Croatia. They will go into the stratosphere and after recovery they will be returned to the schools for analysis and of course we expect them to publish the results.

More on this soon.

This is just one of several activities being undertaken by Team Stellar in the name of STEM Education – Science, Technology, Engineering, and Mathematics. Jason is 11 years old and will just turn 12 when we assist with this flight and will have just completed his first term in high school (year 7). He will be attending Sydney Secondary College – Balmain Campus just as his two older sisters did.

These will be larger balloons that will be needed to lift heavy payloads and to get them into the stratosphere before they explode and return to earth. We also expect to have cut-down ability to command the payload to release from the balloon and return to earth.

We will let you know more as we prepare for the flights in 6 months’ time. You can read more here later and more at:

http://teamstellar.org

That is Jason and I celebrating with a soft drink after the successful recovery of UpLift-1, our first balloon mission in December 2011. Jason does the tracking, radio systems and navigation – I just do the driving.
Jason and Robert Brand Recover UpLift-1

UpLift-1 Flight Data Pt-2 (Archives)

*** Retrieved from Archives ***

UpLift-1 Facts and Figures 28th Dec 2011 Pt-2

Time for some SCIENCE. I have cleaned up all the data from the flight removing duplicated figures and out of place data that sometimes occurs from having lots of receiving stations all trying to add it to the database. The figures are certainly interesting and even fun to see what is going on during the flight.

Temperature.

Unfortunately, UpLift-1 did not have an external temperature sensor – just a payload sensor. The payload sensor will be useful to see the stresses that the payload has to handle, but due to the thermal properties of the capsule (polystyrene is an insulator) and the thermal wrap around the electronics (bubble-wrap) the payload temperature will be both reduced and delayed slightly. The capsule did have some small penetrations that made its insulation poor and the transmitter also produced some small amount of heat that would have affected the cooling effects slightly. It was mainly the bubble-wrap that protected the electronics from the -40 to -50 degrees Celsius (  -40 to -68F). So what happens and why the cold temperatures?

The atmosphere has many layers and the first that we live in is the Troposphere. The following (Troposphere and Stratosphere) are from Wikipedia:

Troposphere

The troposphere begins at the surface and extends to between 9 km (30,000 ft) at the poles and 17 km (56,000 ft) at the equator, with some variation due to weather. The troposphere is mostly heated by transfer of energy from the surface, so on average the lowest part of the troposphere is warmest and temperature decreases with altitude. This promotes vertical mixing (hence the origin of its name in the Greek word “τροπή”, trope, meaning turn or overturn). The troposphere contains roughly 80% of the mass of the atmosphere.

The tropopause is the boundary between the troposphere and stratosphere.

Stratosphere

The stratosphere extends from the tropopause to about 51 km (32 mi; 170,000 ft). Temperature increases with height due to increased absorption of ultraviolet radiation by the ozone layer, which restricts turbulence and mixing. While the temperature may be −60 °C (−76 °F; 210 K) at the tropopause, the top of the stratosphere is much warmer, and may be near freezing. The stratopause, which is the boundary between the stratosphere and mesosphere, typically is at 50 to 55 km (31 to 34 mi; 160,000 to 180,000 ft). The pressure here is 1/1000 sea level.

Our balloon flight will start at the bottom of the Troposphere 34C (93F) at ground level, pass through the thin Tropopause at a bit less than 17 km (56,000 ft), where temperatures could be as low at -50C (-68F) and into the stratosphere where temperatures could warm to just above or below freezing. The climb will end in the Stratosphere when the balloon expands until it explodes and then falls back to earth and back through the cold. The chart below provides critical data on payload temperatures:

Payload Temperature vs Altitude

Above we see the effect of passing through the very cold temperatures of the Troposphere and then the warming of the Stratosphere – even though it is only warming to about freezing! The descent takes the already cold payload back through freezing conditions in the Troposphere again further cooling the payload to a maximum of -12C (10.4F) before warming to a balmy +3C (+37.4F) by the end of the flight. By the time of recovery 2 hours later the  payload had warmed to outside temperatures.

Thermal delay

The chart below shows an approximation of the outside temperatures encountered during the flight plotted alongside of the payload temperatures:

Payload Temperature and Estimated Outside Temperature

There is a good possibility that the temperature in the Stratosphere was above freezing as the payload was warming up substantially. It is not likely to have been from the electronics as the transmitter was extremely low power with a small duty cycle (10%).

Battery Conditions due to Temperature

Simply put, batteries fail when they get cold. This got a little colder than I would have liked. Extra bubble-wrap would have been helpful or sealing the camera penetration better would have helped. In future, I will do both. The battery volts dropped to very low levels due to the cold, but since they were Lithium batteries they worked okay at -12C (10.4F). Battery volts had fallen from 5.8V at the start of the flight to 5.1 in the extreme cold and returned to 5.8v by the time of recovery of the capsule.

Payload Temperature (C) and Battery Volts

In the graph above the battery voltage had started to recover as the capsule landed on the ground. The size of the batteries meant that they would have remained cold the longest even though the electronics warmed up relatively quickly the thermal mass of the batteries took much longer to warm. The batteries were inside the many layers of bubble-wrap.

More on the flight data in the next post

Success – UpLift-1 Recovered (Archives)

*** Retrieved from Archives *** Success – UpLift-1 Recovered

UpLift-1 Flies to 26.161km Altitude

A quick update to tell you of our success. My son Jason (9) and I did it – 26km up – 15 miles – For 15 minutes we probably had the highest thing on planet earth. We got about 1/4 the way to space! In the photo at right, that is Jason in the field with the balloon about to launch.

The weather was clear and the skies almost clear of clouds when we launched the UpLift-1 weather balloon from Rankins Springs near Goolgowi in central NSW (Australia). We were an hour late but had about 20% of the town out to help! I think that we were told that the area had about 120 people and Rankins Springs has about 50 residents.

The flight lasted about 2 hours 40 minutes and landed about 4 fields from the road and we had great difficulty in driving to the landing site.

During the flight, the electronics got to -12C (12F) and the outside temperature got down to about -50C (-58F). As it climbed out of the Jet Stream, the atmosphere warms up to a balmy 5C on a good day. The low temperature caused the battery voltage to drop to 5.2v on the normally 5.8v battery. After it warmed up on the ground, the battery voltage returned to 5.8 volts.

The maximum recorded altitude was 26.181km – 85896 feet – 16.2681 miles. More in a couple of days. Some photos below for hold you over until the full story can be posted. The tracking worked perfectly.

Launch Site:

Launch Site - Rankins Springs

Path:

UpLift-1 Fulll Path

Landing site (X):

UpLift-1 Landing site

Recovery:

UpLift-1 Recovery

Rejoicing with a ginger beer (soda/soft drink):

Jason and Robert Brand Recover UpLift-1

One of the recovered photos:

UpLift-1 Camera view

More in a couple of days…

UpLift-1 APRS Tracking (Archives)

APRS – The Best Balloon Tracking Solution

There are many ways to track balloons. There is the Radiosonde, Mobile Phone (3G), HAM radio APRS and many more. Since I both work in Radio Telecommunications and I am a HAM radio operator (VK2URB), then it is an easy choice. The amateur radio APRS system is ideal.

So what are these systems in brief:

Radiosonde: Wikipedia says: “A radiosonde (Sonde is French for probe) is a unit for use in weather balloons that measures various atmospheric parameters and transmits them to a fixed receiver. Radiosondes may operate at a radio frequency of 403 MHz or 1680 MHz and both types may be adjusted slightly higher or lower as required.” This sounds more like a license is required and special Radiosonde equipment is needed.

GPS enabled mobile / cellular smart phones: We all know what these are, but do they work?. Firstly you had better hope that your payload drops in a coverage area. These work by sending an SMS to the phone on the balloon and it then relays its position back to you via another SMS. Mobile telephone coverage in rural areas might not allow you to get a fix on the balloon as it parachutes back to earth. There is also the issue of the GPS receiver. Most do not work at heights over 60,000 feet (20kms) and thus you do not know how high it got or when it is descending. Many people on a tight budget try to use cellular phones and many have great success.

UHF Tracking: Similar to Radiosonde, yet it operates on a low power UHF channel, often used for garage door openers, etc. It transmits the co-ordinates for the GPS location and must be tracked by radios especially set up to receive the transmissions. The data is often ported to the internet for display on a web page. Handheld yagi antennas are directional and look like UHF yagi TV antennas seen on rooftops and are used to track the payload when it is on the ground or in the air.

APRS_TestTrackHAM Radio APRS:This is the choice that I feel best suits the situation and given that I already have a HAM license, then I do not have to ask others to help. What is APRS?: Wikipedia says: Automatic Packet Reporting System (APRS) is an amateur radio-based system for real time tactical digital communications of information of immediate value in the local area. In addition, all such data is ingested into the APRS Internet system (APRS-IS) and distributed globally for ubiquitous and immediate access. Along with messages, alerts, announcements and bulletins, the most visible aspect of APRS is its map display. Anyone may place any object or information on his or her map, and it is distributed to all maps of all users in the local RF network or monitoring the area via the Internet. Any station, radio or object that has an attached GPS is automatically tracked. Other prominent map features are weather stations, alerts and objects and other map-related amateur radio volunteer activities including Search and Rescue and signal direction finding. APRS has been developed since the late 1980s by Bob Bruninga, call sign WB4APR, currently a senior research engineer at the United States Naval Academy. He still maintains the main APRS website. The acronym “APRS” was derived from his callsign.

Note the unusual off-white unit connected with wires in the top picture – it is the special high altitude GPS receiver. It will work up to very high altitudes but sacrifices some accuracy.

The picture above is the APRS Test Track around a street block on a hill near my home. Not precise, but very close. I was shaking the thing as I walked to make it hard for the system. I walked counter / anti clockwise from near the top without shaking and then where it goes a funny in the last quarter of the short walk I was really shaking it wildly. The unit reports on many details. These are:

VK2URB-11 is the balloon call sign

2011-09-10 02:59:41z is the date and time in GMT/Zulu

7 km/h was my walking speed

248 degrees was my bearing

alt 80m was my height above sea level

05.8v was the tracker battery voltage

20C was the temperature – about 70F

The other data is pressure, HHMMSS, and number of GPS satellites, the digipeater used (if used) and the iGate used.

Agilant systems APRS transmitter for balloonsPluses and Minuses

APRS is could always be better and there are not too many iGates (APRS gateways into the Internet) in rural areas, so you must check first. In fact I have chosen to have my balloon drop near Parkes for that very reason. There is an iGate in Parkes and the Digipeater (digital repeater) at nearby Mt Canobolas will also pick up the transmissions from my balloon. I have also chosen an area for good 3Gcellular coverage to assist with tracking and maps. Just to be sure, I will have a digipeater in my car so that if I am not too far away the position will be relayed by my car to the Internet for easy tracking. The unit I have chosen is specifically bought for ballooning. It is from Argent Data in the US. The unit weighs only 160 grams (5.6 ounces). It transmits half a watt (500mW). It is pictured top right and is a pre-release model.

The next issue is finding it when on the ground. Radiosonde and APRS are well suited to this task, but the APRS has a few tricks up it’s sleeve. Fist it might be able to radio its GPS co-ordinates to the Internet tracking system. As I get close with the digipeater, it will also do that job if no other iGates are in range. Secondly it may be picked up directly by my handheld radio, nice, but since it only transmits for 1-2 seconds, it will be hard to get a fix on the unit. Finally I can decode the data with my iPhone and simple read its exact co-ordinates. Nice! That is the directly decoded packets on the right. I did the test inside my house so the GPS coordinates will not be seen.

On the minus side, there is the need for an amateur radio license and access to the expense and homemade equipment that is either out of reach of some people financially or technically.

I also replaced the long general purpose whip antenna that you can see on the top image with a highly tuned light weight dipole. It is made of hollow brass and this also makes it easy to slide some stiff wire inside the antenna for tuning. The wire was then soldered in place to get the tuning very precise. This maximizes the antenna’s radiation ability at the precise frequency of the APRS system. We are using VHF at 145.175MHz. The pictures below show the modification. The work was done by my good friend Bruce who I have worked with on and off for over 40 years. He is also an amateur radio operator (VK2ZZM) and I am very appreciative of his advice and help on the APRS side of this project.

APRS Transmitter dipole antenna

The white Styrofoam under the unit is the lid of the UpLift-1 capsule. The antenna is mounted on a small printed circuit board, The copper wire is used to add strength to the copper on the board in case of mechanical failure that may make the copper peel from the board.

APRS Tracker with dipole antenna - back

The rear side above showing the bolts that pass through to the battery mounts on the tracker unit. A small amount of “locktight” was placed on the nuts to make sure that mechanical vibration did not make them fall off.

Spectrum / Network Analyser tuning the APRS tracker Dipole antenna

This is a state of the art network analyzer. It is measuring Return Loss. Send a signal to the antenna and what is not radiated comes back. The dip means that it is tuned to the frequency and radiating well. It is right on the tracker frequency. The Marker frequency. It is perfectly tuned and radiating the signal – not much is being reflected back into the cable. It is best practice as far as radio is concerned.

I will post a link to the tracker website that I will be using just before the day, but this link will let you see the few test drives that I have done in Sydney: http://aprs.fi/