RaDAR – QRP Satcomms and a road through the twilight zone

Saturday was a special day.

It started with portable QRP communications from the stadium in a nearby town called Ottosdal, famous for the one and only night marathon in South Africa.

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Conditions were not good on 40m but I managed a few QSO’s, three of them morse code, my favourite mode. Ottosdal lies on the border between grids KG33 and KG23 and part of my plan was to activate KG23 via satellite, a grid my friend Andre, ZS2BK needed.

I’d done a recce beforehand to find a safe spot to deploy for RaDAR SatComms and packed up and left, planning to return after the QSO’s.

It was next to some grain silos with an awesome dam across the road. Strangely there was no one there unlike the rest of the town. As per usual, finding true north is a requirement before any satellite communications are possible. You need to know where to point the antennas!

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I had a successful QSO with Andre, Christi ZS4CGR and Rickus ZS4A who was demonstrating RaDAR SatComms to two other hams in Bethlehem in the Free state.

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I returned to the stadium, I’d already entered for the night’s half marathon. 18:30 local time is when the gun is fired.

Here are a few pictures I took en route, a most awesome run / jog / walk on a road with miles and miles of diesel filled lanterns.

The starting line.

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As darkness set in.

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Almost halfway for the half marathoners and almost a quarter of the way for the marathoners, an out and back route.

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The half marathon turning point. 10.5 km back to the stadium from here. A spectacular race!!!

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Good training for RaDAR.

73 de Eddie ZS6BNE

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RaDAR – Automating field SatComms

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I’ve always promoted SatComms for use in RaDAR. It certainly has its place there.

Recently there has been renewed interest in the satellites in South Africa and we are starting to use the relatively new cubesats and the CAMSATS. The CAMSATS prompted this article as I have some new questions that need answers. The CAMSATS are amazing satellites and they fly in “Formation” requiring a lot of attention from the satellite user switching in the appropriate frequencies as each flies from horizon to horizon in quick succession!

Working “half duplex” is fine when there are two people on the satellite at one time but when there are three or more it becomes quite challenging with great risk of interfering with possible other QSO’s taking place within the pass band of the transponders.

It’s still good practice to do things by hand and should be practiced but once mastered it’s more convenient to utilize a little computer assistance. I used to use SatPC32 which worked well with the 847 I used to have. CAT control of dual VFO rigs for satellites works but it has its problems! While the VFO’s are updated and you press the PTT at the wrong time it’s possible that you may transmit using the wrong VFO, especially with the 817. The 897 seems to be a little more “tolerant”. If you are monitoring the downlink on another radio it’s possible then that you transmit on the downlink frequency blasting your headphoned ears with strong audio! This is the problem I have and I need to devise a means of working RaDAR SatComms in the best possible way. It also needs to be done to protect the receiver radio!

The proposal.

Just this weekend I rebuilt my HP 210 NetBook computer to control the FT-897d via CAT only to initially set up the uplink and downlink frequencies on the dual VFO’s (Working SPLit). The receive VFO frequency will then indicate what frequency the FT-817nd should be set for the downlink. From there on it’s manual tuning of the higher frequency being it the uplink (u/v) or downlink (v/u) working full duplex and able to listen to your own signal through the transponder and of course others. The process of “Netting” is used to get onto another stations frequency.

Note, each radio has a direct coax connection to the 2m or 70cm yagi of the Arrow antenna. I use the more flexible (but lossy) RG58cu coax but it works acceptably well.

There is still quite a measure of manual control but better than working “blind” and of course keeps the RaDAR operator sharp and focused without the need to look up written or printed frequencies on paper (usually in the dark). Of course this relies on the computer.

I have found too, that tracking the satellite by hand is easier while standing so the rigs should be arranged such that they are easily accessible even while standing.

I use the 817’s shoulder strap and hang it over my Arrow’s tripod but still need to find a way to do something similar with the FT-897d. I power both radios off a 7 A/Hr SLAB that usually sits on the ground.

RaDAR – The last challenge for 2016

I chose my four hours of twenty four to coincide with returning from a nearby town where we took young Eduan to meet an old primary school friend for his birthday. After a hearty breakfast, they watched a kiddies movie together while Elrika and I did some window shopping at the mall.

We got to the RaDAR playground (just) in time and my first deployment was for SatComms on SO-50. Many of us in South Africa have the experience but are rusty. Using my TH-D7A(g) (Running on four AA alkaline cells) and Arrow antenna, I was able to have a QSO with Rickus ZS4A before the bird went over the horizon. I even forgot to tune for doppler!!! I was lucky …..

That earned me my first RaDAR contact and five bonus points for the first satellite QSO, counting my movement to the first position as travelling by car even though the travelling distance from the mall was close on 150 km, a little more than the requirement 🙂

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The app I use for satellite pass predictions is “ISS Detector” for Android. It works very well for the purpose of RaDAR and always accurate. A reliable tool!

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I had my minimalistic RaDAR kit packed and ready. It includes the FT-817nd with eight AA internal batteries, straight key, mic and 40m end fed with coupler. I moved out, on foot to the next deployment point.

I use the Android app “Ham GPS” to determine my grid square to 10 character accuracy. Also a great tool for RaDAR!!! An ideal website for displaying these grids can be seen here.

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It was quick to get the end fed deployed using a tree branch and nylon rope to raise the middle section of the end fed as high as possible, in this case around four meters above the ground. Perfect NVIS configuration for 40m.

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As with all my field antennas, I build in a bungi shock system to protect the antenna from the wind or tripping over the wire. I quickly got the rig deployed and started to look for contacts.

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I managed to work ZS5HAC, ZS3VDK and ZS4A all on 7.090 SSB. Signals were reasonable especially ZS3VDK who was very strong. I took a video which I will later edit for You Tube upload. There was no CW activity on the band …..

It was time to get back home where I’d left the satellite equipment. SO-50 had just gone around the world and coming over the horizon again. I quickly packed up and walked / jogged back home.

This time round it would be classified as fixed station RaDAR. I got everything ready and made contact with Andre ZS2BK and I remembered to tune for doppler! Unfortunately no other signals could be heard on that pass.

The next part of the plan was to take the QRO kit for a walk ……. it started to rain.

I deployed on the patio, the FT-897d and battery supply. I lifted the link dipole into the tree in the garden and set the links for 20m. All I could hear was an obliterating noise, 59+ which made communications impossible. I tried switching off the power to the house but the noise stayed. It was coming from somewhere else.

I called it a day ……

Lessons learnt. Certainly the minimalistic RaDAR setup excelled in it’s purpose. Very light weight and easy to move quickly. An effective communications method. Satellite communications were reliable within the footprint of SO-50. I even managed to activate the transponder myself as it came into view (74.4 Hz CTCSS).

Till next year!

73 de Eddie ZS6BNE

 

RaDAROPS Planning – 2016 April the 2nd

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My ops planning is guided by suitable satellite passes. After doing tests with SO-50 the past weekend I’d really like SatComms to be part of the challenge again, it’s been a while. Unfortunately not many other hams in range are satellite active anymore. Kieth, ZS6TW may be able to save the day.

Local times in South Africa are UTC + 2

06:00 – 08:00 Get ready for the ops, breakfast etc.

08:00 – 12:00 Field moving operations.

12:00 – 13:30 Lunch, operations from fixed location.

12:17 – SO-50 S ==> N (E)

12:34 – FO-29 S ==> N (E)

13:30 – 16:00 Field moving operations.

14:19 – FO-29 S==> N (W)

14:56 – AO-7  S ==> N (E)

16:00 – 17:30 Supper, operations from fixed location.

16:47 – AO7   S ==> N (W)

17:30 – 19:00 Field portable (Not moving) operations (Digital).

19:00 – Pack up and move back to fixed location.

 

Satellites – It’s been a while

At one stage I was very involved with the satellites working them just about every day and sometimes multiple times a day. In South Africa as far as I know there is no longer satellite activity.

My son Edwilll wanted to make a video of the “typical ham” and so I thought let’s look at the satellites for an example.

For the past few months I have downloaded many satellite applications on my Android smartphone and used them for predictions. The next predicted satellite was the relatively new satellite Hope-1 alias HO68 or XW-1, a Chinese built satellite who’s transponders have gone faulty but the CW beacon still working (Fortunately). The satellite measures 480mm x 600mm and weighs around 60Kg.

AOS (Aquisition od signal) was from the NW (335 degrees) and EOS (End of signal) SW (280 degrees) with a maximum elevation of 18 degrees. Sure enough the satellite was right on time and we could hear her beacon. I had to go to the AMSAT website at http://www.amsat.org to find out what thef requency is ie 435.790 MHz +- doppler (Tune higher at AOS)

I used my Arrow dualband yagi antenna and FT-817ND to “make the contact”. Brought back some good memories and I proved I have not lost the ability to plan satellite passes!