Category Archives: aprs

Sending Christmas Greetings to the ISS

There was much media coverage in the UK of the “Santa pass” (Telegraph, Daily Mail) The International Space Station passed over the UK in the late afternoon and early evening on Christmas Eve and around 17:20GMT promised an especially bright display in the dark skies. So imaginatively we were asked to observe and imagine that the bright moving point of light was actually Santa off delivering his presents.

As luck would have much of the UK had a crystal clear sky and I even managed to get my 80 plus year old Mother-in-law out in the garden to watch the spectacle. She was impressed and it was great to overhear lots of excited children coming out in the nearby homes to watch Santa as he flew overhead.

Back in October 2013 after becoming a newly licensed radio amateur I managed to send APRS packets to the International Space Station which were digipeated and received back on earth by other operators. Back then I used a lowly Baofeng UV5R handheld and I decided to repeat the exercise this time using the FT857D (this time running around 20W) to talk to Santa!

The computer I used back then has been decommissioned so on the laptop I installed the UISS program from ON6MU which makes easy work of APRS to the ISS and instead of the cumbersome AGWPE I used the excellent soundcard modem from UZ7HO.

I attempted to send a message on the pass at 15:43 but failed completely, discovering I’d got my soundcard incorrectly set up. I corrected this and left the autobeacon mode running in UISS during the Santa pass and checking back much later could clearly see I’d sent and had a message repeated back from the ISS.

Checking the ariss website ( I could see the repeated message had been received by another station and my position was showing up on the map (M0NRD)

I have successfully done it again today on Christmas Day! As the raw packets below confirm.

M0NRD>CQ,RS0ISS*,qAR,DM2RM:73' Happy Christmas from Andrew IO93OB
M0NRD>CQ,RS0ISS*,qAR,MB7USS:=5304.08N/00048.47W-73' Happy Christmas from Andrew
M0NRD>CQ,RS0ISS*,qAR,HG8GL-6:73' Happy Christmas from Andrew IO93OB

It was a nice achievement and another nice Christmas present was achieved early this morning while running WSPR on 40m, managing to get received in New Zealand

Anyway enjoy the rest of the festive season and I wish you all the best in 2015

My APRS broadcasts received by the ISS

This evening I managed to successfully send some APRS messages to the International Space Station that were successfully digirepeated. It might not be a major technical achievement but after monitoring and decoding many passes in the past to now actually send something myself 300 miles up to something traveling at 5 miles/second left me feeling a little chuffed!

I screen capped the evidence from the website which documents Amateur Radio data digipeated by the ISS. In order to appear on the page, a position report in a valid APRS format must be received and then digipeated through the ISS system, then be heard by an internet gateway station, which then forwards it on to the APRS Internet System.

Okay it sounds a bit more impressive when put like that 😉

The map showing received stations, M6GTG is me!
The detail of my report
List of stations with time stamps, showing me!
List of digirepeated messages

The equipment I used was very similar to that I used for the APRS IGate setup last month.

It consists of a small embedded PC running embedded XP, the sound card output was connected to the microphone input of my Baofeng UV-5R+ operating in VOX mode set to 145.825MHz. The radio was connected through my power/SWR meter in to the X-50 antenna. I used the UV-5R+ instead of the UV-3R since it has a little more power and better audio. I had a SWR of around 1:1.2 and outputting 4W.

The software I used was UISS from ON6MNU and the AGWPE packet engine. It has taken a little time to work out how to setup UISS into auto-beacon mode and putting in the time of the next decent pass (approx 45 degrees elevation) I set it to broadcast position and text data messages every 30 seconds.

The embedded PC running UISS
UV5R+ in VOX mode on 145.825MHz
The power meter showed 4W output, SWR about 1:1.2

I stood out in the dark, hoping to see the ISS pass over but the cloud cover was too thick and monitored using a handheld scanner. I heard my transmissions obviously and the ISS broadcasts as it repeated received messages, but I didn’t know if any were mine till I got back to the PC.

APRS IGate – “If you build it they will come”

The 2013 National Hamfest is taking place this weekend, it is held over two days at the nearby Newark Showground. I will be visiting tomorrow (Saturday) as work commitments prevent me attending today, so no doubt all the best second hand bargains will be gone!

Seriously I am looking forward to it now that I am a proper licenced radio amateur. The Hamfest has been held at this venue for several years and always gives me the opportunity to hear the VHF/UHF bands full of local chatter. Normally the chatter consists of operators trying to give each other directions! The showground isn’t very well sign posted from the local approaches.

In previous years they have a had a call-in station operating on the usual channel (S22) 145.550MHz, but today it wasn’t in evidence well not at 10:00am when I listened in, instead there were several local operators chin-wagging with the occasional calls asking for the rally call-in.

This year the Hamfest have enlisted the services of the BritishAmateur Television Club to give live internet television feeds. Go to the live eventspage and there are two streams and currently a third from GX3RCM available.

One thing I hinted at previously was to experiment with APRS and I really wanted to get an APRS IGate set up in time for the weekend as I was expecting a number of the attendees at the Hamfest would be using it.

From the Wikipedia page 

“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.”

There are two short video on youtube which describe the APRS system and the role of IGates, an IGate is basically a receiver station that puts locally received messages into the APRS-IS system.

I have a Baofeng UV-3R handheld transceiver which I have pressed into service. I don’t have a dedicated TNC so am using the compute sound card to receive and send audio to the transceiver via the handset connector and am using the AGWPE as a software modem/TNC that is used by the APRSISCE/32 client to create the station.

It should have been straightforward as I already had an eQSO interface which should have provided an isolated audio interface and control of the PTT on the UV-3R, all I had to do was create a suitable connecting lead.

During the commissioning the station seemed more than capable of transmitting messages but it wasn’t receiving anything, checking the audio coming in to the PC and I was getting virtually nothing! The interface was dismantled and the signal scoped. Oddly it seemed the UV-3R really didn’t like the isolating audio transformer and this seemed to shorting the output from the transceiver, so now at present it is just directly connected.

Sadly while using the scope to see the signal the ageing scope decided to commit suicide in a loud bang and cloud of acrid smoke, oddly despite the pyrotechnics it was still working till I turned if off and now it won’t turn on! I suspect a capacitor in the switch mode supply has died in spectacular fashion.

Anyway I digress, having got the system working properly late last night it is currently running and has indeed received a number of stations this morning as made their way to the Hamfest.

The UV-3R probably isn’t the best choice as a receiver as its audio is pretty dreadful but it seems to work, it is connected to a generic X-50 antenna stuck on the top of a 4 meter pole. The pole is in fact a 5 meter telescopic painting pole costing less than £16 from B&Q.

I haven’t fully extended the sections as the joints could be potentially weak, but it is anchored to a metal fencing pole and then with three guy ropes it seems sturdy and has stood out all week, just lowered down slightly when not in use.

X-50 in the garden

You can see a map of the current APRS stations at my station statistics can be seen here

This was a snapshot of the map earlier showing the cluster of stations at the showground

Quite a few operators are using their smartphones rather than radios to update their position. I have installed APRSdroid on my phone (not free from Google Market, for free version go to developer website see Pete’s 2E0SQL comment below, and you need to be a licenced amateur with a valid passcode) but it gives me a warm feeling to know my humble set up has allowed some people to show up at their destination using their ‘proper’ radios.
The shack – APRS setup on the left hand side

Still waiting! But did get a new toy

Everyday last week I have picked up the newly delivered post with growing anticipation only to be disappointed. I am still waiting for the official notification of my foundation pass from the RSGB so I can apply for my call sign. They do say it can take six days from when they receive the tests, so hopefully it will be early this week.

Something did turn up in the post on Saturday morning, I was awoken at 7:30am by a knock on the door, bleary eyed I took delivery of my latest purchase from eBay, a Baofeng UV-5R+ handheld. This is a Chinese made VHF/UHF dual-band FM transceiver suitable for the 2 metre and 70cm bands. The package came with an official Baofeng USB programming lead and a small handheld speaker/microphone that can be plugged into the main unit all for the pricely sum of £37 including postage.

I can admit now to already owning a Baofeng UV-3R which I have had for some time but have only ever used for receiving and the odd transmission on the PMR446 band. It cost about the same price and considered it a bargain then but on first impressions the UV-5R+ seems even more of one. It is a much more substantial device, it feels very solid in the hand. The display is bright and clear and the proper volume control and keypad make for a more pleasant experience, you can actually turn it down unlike the UV-3R which is deafening or off! It came with a proper drop in charger, a USB programming lead and a small hand-held speaker/microphone/PTT unit.
These units are just stop gaps until I get around to getting a decent amateur rig, the current front runner being the Yaesu FT-857D which is a nice small affordable(ish) unit giving me all-modes on HF and VHF/UHF. The 2013 National Hamfest which takes place in couple of weeks, right on my doorstep, could be a dangerous place for my credit card!
As well as having a chinwag I have already got a plans for a project to investigate APRS. I am hoping to use an old echolink/eQSO interface I built, around 10 years ago, linked to the UV-3R and a computer sound card. I am still investigating it but it seems the software which will be AGWPE to act as a TNC driven by the APRSISCE/32 the Amateur Radio client for windows.
I am especially looking forward to trying to contact the digi-repeater on board the International Space Station, some details here.   

APRS decode of last nights ISS pass

Did manage to get the yagi out last night for the ISS pass at around 19:20 GMT. Opted for the Realistic PRO-26 receiver as I’d forgot to put the DJ-X10 on charge. Managed to capture a decent audio file of the ARPS transmissions that lasted just over 10 minutes long. Processed it later with Multipsk.

As you can see from the map above, did manage decode a reasonable number of APRS transmissions. Had a couple of faint transmissions as the ISS came from the west over the Atlantic but the activity didn’t really start till it was in range of mainland Europe.

I know Santa is bringing me a Funcube Dongle, so lots more experiments in the New Year!


This week with the launch of the Russian Soyuz TMA-03M spacecraft to the International Space Station it occured to me that I have never seen it pass overhead or indeed made any effort to hear any transmissions from it. So off I went to the website to check the pass predictions for the week and was pleasantly surprised to discover that over the Christmas period there are a number of good evening passes (the potenitally visible ones are also listed on the Guardian website)

There are a multitude of  frequencies to potentially listen to, some of the operational ones could be quite interesting over the next few days, but at first I was interested in some of the ARISS frequencies.

On Tuesday (20th Dec) evening I popped outside with the 2Meter YAGI, Alinco DJ-X10  and my new found Satellite-AR Android App I did manage to see a faint moving point of light briefly as it came up over the horizon, but quickly lost it due to cloud cover and I think it passed into the Earth’s shadow.

I was able to carry on tracking it using the Satellite-AR and picked up some very strong data bursts on 145.825MHz this is the APRS/Packet digirepeater. More details on the ARISS website. APRS in simple terms allows ham operators send a coded data message usually containing their GPS location, call sign and other information. This is received by the digirepeaters and rebroadcast, in the case of the ISS the digirepeater is moving around the earth at nearly 5 miles/second.

Last night (21st Dec) I used the loft mounted antenna and my Realistic PRO-2006 and captured and decoded some of the data on my PC using MultiPSK

Some of the data as it appeared in text form on the screen showing the coordinates, call signs and comments.

@215120h5218.35N/01624.62E-73! via ISS’yI1l -/]Paco en Leganes=
:F6GWB    :ack02!5214.25N/00043.40E`Aprx v2.02 SatGate@215356h5218.35N/01624.62E-73! via ISS=4542.75N/01142.00E`73′ Via ISS de Cris {UISS52}=3919.07N/00259.59E`73′ Via ISS {UISS52}!5310.76N/00532.86E- – 73 – Roland – -`vDjl -`73’s via ISS ea5hzz.raul@gmail.com_” :SP1TMN-6 :73{17 ‘vC$l S]73 FOR ALL=
=4549.52N/01600.66E`[JN85AT] 73 via ISS de Robert – Zagreb – Croatia
!5310.76N/00532.86E- – 73 – Roland – –

  Some more good passes this evening that I might get a chance to capture with YAGI and weather permitting might get to see the point of light as it crosses the sky!