Broadcast - 21 May 2023
NTARC News for Sunday Broadcast – 21st May 2023
Many members of NTARC were present at the “Celebration of the Life” of Norm VK7KTN, which was held on Friday at Mersey Gardens Devonport. The NTARC tribute was presented by Peter VK7KPC.
Last Wednesday night Andrew VK7DW took us into the wonderful world of the GreenCube satellite, specifically Italy Oscar 117 or IO-117, which was launched from French Guiana in July 2022.
The spacecraft main payload is composed of a pressurized vessel of approximately 20cm x 10cm x 10cm.
Within the pressure vessel is the experiment with microgreens seeds which hopefully will grow into little green plants, like the ones you can grow on your window sill. It is currently the farthest experiment ever of plant cultivation in microgravity. The satellite has the ability to monitor air composition and pressure, humidity, air recirculation, lighting conditions and, ultimately, to optically monitor the plants growth through Visible and InfraRed cameras.
The secondary payload developed by University of Stuttgart is a PPT (Pulsed Plasma Thruster) motor that will be used as additional attitude control system.
The third payload contains telecommunication systems including a Digipeater. This is where things get really interesting!
Andrew covered the basics behind the third payload and its implementation.
It uses an AX100 transceiver from GomSpace with a transmit frequency of 435.310 MHz Upper Side Band using Gaussian Minimum Shift Keying more commonly known as GMSK modulation. This is the modulation scheme used in GSM/CDPD (Cellular Digital Packet Data) technologies.
Telemetry function sends data periodically every 45 seconds. The Digipeater is scheduled to operate during the weekends only (from Friday at 00:01 UTC to Sunday at 23:59 UTC), with possible future extensions.
The Digipeater antennas are omnidirectional and circular polarisation.
Andrew found that the initial co-ordinates of satellites path were incorrect as far as the information passed on to the public was concerned, this makes it a bit hard to point something somewhere at some time. He thought it might be worth trying a simple vertical antenna and just listen to the frequency. Eventually his perseverance payed off and he started receiving the telemetry signal.
Moving forward somewhat, the predictive flight path information is now available and Andrew has set up his tracking app and motorized azimuth and elevation hardware on his beam. One thing to note is there is no beacon on this CubeSat so listen for the telemetry down link which occurs every 45 seconds.
Andrew went on to discuss hardware and software required to successfully utilise the on-board Digipeater facility for this satellite.
A 70cm receiver to decode packet data, or a transceiver to also utilise the Digipeater function.
Directional antenna, 10dBi recommended but fixed antenna can work.
Windows PC (can use OSX with 3rd party software)
Audio connection between radio and computer (may require sound modem)
Satellite tracking (web or software)
Digipeater software (free)
Modem software (free)
Packet forward software (free)
Advanced software operation would include antenna control for azimuth and elevation
And finally VFO control software for Doppler correction
Andrew then went on to discuss the “nitty gritty” of conducting QSOs via the Digipeater in real-time and produced many screen shots of QSO messaging logs.
The other Digipeater mode is “store and forward”. This delaying option will allow him to send a message and have the broadcast delayed by a couple of hours by which time the satellite foot print could be on the other side of the world when the message is broadcast. Then wait for the delayed reply from another amateur.
Andrew was surprised by the flood of Japanese operators on his first CQ. The main take home from this when establishing a QSO was “Don’t Panic” as the satellite footprint is very large and each ‘visible’ pass can last up to one hour, allowing plenty of time to think.
This was an excellent and informative presentation by Andrew.
The tracking information and software links are available in the text version of this broadcast.
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Websites
• N2YO http://www.n2yo.com/
• AMSAT-NA http://www.amsat.org/track/
Software
• Gpredict http://gpredict.oz9aec.net/
• MacDoppler https://www.dogparksoftware.com/
Apps
• GoSatWatch https://apps.apple.com/
• Heavens-Above https://play.google.com/store/apps/
Decoding
· S5Lab GreenCube team provide software: GNURadio, GreenCubeTNC and GreenCubeDigi
· UZ7HO created the digi app and custom sound modem after the S5Lab release, most everyone has migrated to UZ7HO now
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UPCOMING EVENTS
The TestNet and TechNet session - Wednesday the 24th of May. TestNet/CW course on 3.580MHz from 7pm till 7.30pm…. and a TechNet on 3.567MHz from 7.30pm till about 8.30pm. Your host for the evening will be Nic VK7WW.
Coffee Morning - held every Friday in the NTARC Club rooms. Time is from 10am to noon and we look forward to seeing you all there. Why not pop in and join us for a cuppa there is endless tea and coffee along with biscuits available for a donation.
The Club Technical night - The next session will be on Wednesday the 31st of May and will commence at the usual time of 7.30 pm, running through to about 10.30 pm, at the Club room Archer Street, Rocherlea.
FINALLY - A reminder to all members that if you have any items of news you would like added to our weekly roundup, no matter how trivial, then please email them to the Secretary at the following address news@ntarc.net all items to be received no later than 5pm on the Friday prior to the Broadcast.
That’s all folks,
73 from Stefan, VK7ZSB, Secretary NTARC.
The tribute to Norm VK7KTN from NTARC
Norm was an Amateur Radio operator and had a unique worldwide call sign, VK7KTN. To obtain this call-sign he had to pass an examination run by the Post Master General or the PMG as we used to know it. Not an easy exam to pass and one club member recalls that Norm and his friend Gerry Sulzberger worked towards their Amateur Licenses via 'night school' at the Launceston Technical College as it was then. They realised their dream in the late 70s and were issued the call-signs VK7KTN and VK7ZA respectively.
Not sure where this fits on the time line, but one member recalls that Norm and Gerry used to do check points for car rallies, which were usually overnight. He remembers once when they made skid marks with their vehicles in all directions at the check point intersection so it was not obvious to the navigators which direction they should take. Sounds like something this pair would do, but it does show he was already happy to help out.
Norm and Lorraine joined NTARC in 2009 and in 2012 Norm was elected as “Committee Member”.
A year later he took on the role of Treasurer which he held until 2015.
Also in 2013 he took on the newly created position of the NTARC Safety Communications Coordinator and he passionately held this position until 2022, when he reluctantly stepped down due to ill health.
Norm has been involved in the Premier Equine event The Tom Quilty Gold Cup Endurance ride. This is a national event held in a different state or territory each year. This gruelling event is where horses and riders attempt to cover 160 kms in a twenty four hour period.
Tasmania hosted a Tom Quilty in 2012 at St. Helens. Norm was one of the NTARC crew to assist in providing Safety Radio Communications at the various checkpoints. NTARC has continued its communications support for local and state Equine rides ever since, thanks to the strong relationships with Equine clubs and organisations that Norm had built up.
He really must have enjoyed his 2012 Tom Quilty experience because in 2017 while he and Lorraine were on a caravanning holiday to the mainland, they ended up in South Australia. South Australia just “happened” to be hosting the Tom Quilty at the time! As the event turned out to be shorthanded and Norm being Norm, he immediately stepped in to assist with communications at Ride Base.
In 2018 it was Tasmania’s turn to host the event in Scottsdale, so Norm stepped up to the plate and took on the role of Safety Communications coordinator. Norm was in his element. Being a “people person” he was able to effectively liaise with organisers and provide leadership for the NTARC team, helping to make it an excellent and fun event.
Norm and Lorraine were always very active in supporting the club’s many and varied activities and were sorely missed at Friday morning teas after they relocated to Devonport and could only occasionally make the trip.
As one of our club members put it “He was a good bloke”…….
Vale Norm VK7KTN, we will miss you.
