The RSGB have a series of Christmas Cumulative contests covering 50/70/144 and 433 MHz. The contest is a chance to put down that turkey sandwich and head out to play some radio in the winter sun. The contest run for 2 hrs, and activity is over 4 days. You can read the rules online, and activity is typically quite high.
Icom 7100, 9e Portable Tona and RF power was provided by a Linear Amp 300w solid state amplifier. The mast was a Racal PU 12 at 5m as the band was wide open with tropo propagation, this provided some interested DX. Mains power was provided by a silent running 2KW Honda generator.
We managed to work 51 stations, with our best DX into Spain, EA1FDI in IN53 at 1143 KM.
The QSO map showed some great openings to the South and East.
The temperature dropped quickly once the sun set, providing a spectacular sunset and the motivation to pack away quickly. Altogether a great afternoon playing radio, with some great propagation for a change.
Thanks to everyone we worked, and all the best in 2017.
NOTE:- It has been recently discussed on the UDXF Yahoo group that Sorcerer is using an old freq/site list – you may get correct decodes, but not correct site IDs. One option is to consider some of the other methods of decoding ARINC on this page.
This article was updated on 28/11/17 to reflect some changes highlighted by Mike KA3JJZ
ARINC 635 is an HF data protocol defined in a document of the same name. The data is sometimes described as HF ACARS, and uses this protocol to exchange packets of data with aircrafts and ground stations over HF. The frequencies and ground stations are designed to provide worldwide HF coverage, and you can listen and decode them with any HF or SDR receiver.
I used the Sorcerer software and previously described using the program to decode other digital modes. The program provides you with decoding opportunities not available in other programs and provides an ideal opportunity to experiment with decoding HF data. I’ve also written about VHF ADS decoding, but this article deals with the HF version of ACARS.
So what is ACARS
ACARS is the Automatic Communication Addressing and Reporting System. You can download a free VHF ACARS decode online. I haven’t checked, validated or used this VHF software, so at this point, cant offer any further advice.
Download Sorcerer, and select PSK then ARINC 635 as your decoder. Tune your HF receiver to one of a number of frequencies, this will depend on your location and the time of day / HF propagation conditions. In the UK I used frequencies listed for Shannon ILR and found 6.532 MHz USB as a starting point, you may also wish to try 2998, 3455, 5547, 8843, 8942, 10081, 11384.
Once on the correct frequency, the program should start decoding.
The message contents vary, but here are some examples.
[MPDU 18:40:06 GND SLOT 1,2 600 BPS ]
Ground station ID SHANNON – IRELAND SYNCHED
NR AIR CALLS 1
AIR CALL 0 = F5
LPDUS = 1
Max Bit rate 1200 bps
[LPDU UNNUMBERED DATA FM GND TO AIR HY0273]
HACARS mode: 2 Aircraft reg: UK78701
Message label: A9 Block id: D [Uplink]
/ESBATYA.TI2/LTBA ARR ATIS T 1820Z EXP ILS DME APPCH 05 SFC/ WET FOR RWY 05 TRL 110 BE CAUTIOUS ABOUT GP AND LOC DISTORTIONS OR INTERRUPTIONS FOR RWY 05 OR 23 AFTER VACATING RWY CONTACT 121.8 VIS 9999
The message above would indicate its directed towards HY0273 a flight is shown as leaving TAS (Tashkent to Istanbul)
Others messages contain location information
[LPDU UNNUMBERED DATA FM AIR SAS150 TO GND]
18:51:20 UTC Flight ID = SAS150 LAT 51 40 43 N LON 0 13 32 E
In this message, I think it is communicating what frequencies are being used/monitored by each ground station. You can match the numbers with the allocated frequencies shown in this table.
Preamble 300 bps 1.8 sec Interleaver FREQ ERR -6.403492 Hz Errors 0
17:18:16 UTC SHANNON – IRELAND DB = 49 SV = 0 GS UP LIGHT OFFSET 10
SHANNON – IRELAND UTC LOCKED Active freqs 3 5
REYKJAVIK – ICELAND UTC LOCKED Active freqs 3 4 6
RIVERHEAD – NEW YORK UTC LOCKED Active freqs 2 4
If you have any further information, additions or corrections please get in touch.
Amateurs often launch HAB containing telemetry and sometimes SSTV of the ability to take and store pictures. The launch schedule is usually published online, its worth starting with this online resource. Tracking is based on an adapted version of FLdigi, this program once configured with your callsign and location will manage the upload to a central server.
Its quite incredible to think you can often receive these balloons at 800 miles or more when they transmit as little as 10mW. I guess it helps if your antenna is 30 Km about the earth.
You will notice on this decode the frequency is drifting a little, probably due to the extreme temperature experienced by the transmitter. Your data will be combined with other stations, and the location of the HAB will be displayed on a map.
This is ROTIO, you can see it has some issues with GPS lock….
Frequency stability can sometime be an issue.
Unfortunately things dont always go to plan, sometimes the conditions are just too harsh or something fails and the telemetry stops.
Its not often you hear 1.8 MHz full of phone, but tonight was that night. The RSGB club calls contest is one of the most popular RSGB HF contest around, and at various times of the year covers both CW and SSB from 1.8 to 7 MHz. You can read more about this contest on the HF contest website.
The idea is for clubs to field as many stations as possible, and for the combined scores to contribute to the AFS clubs score. Exchange is a little unusual, the 4 letter club names can be found here.
Report, Serial Number, ‘Club HQ’, ‘Club Member’ or ‘No Club’, Club Name (a 4-letter club abbreviation)
Running as M1GEO and operating as members of the Camb-Hams provided a great volume of QSO over the 3 Hrs contes. The antenna was a top band dipole with the centre at 30m and Icom 7600 running 32w. Most signals received were very strong, although finding space on the band was sometimes difficult. The QSO total was 120, very respectable considering a break for some food at 21.00 Hrs.
Here you can see George M1GEO doing a spot of antenna maintenance before the contest.
Members of the Secret Nuclear Bunker Contest Group (SNBCG) assembled at Kelvendon Hatch to try 144 MHz (Earth Moon Earth) EME and MS (Meteor Scatter) over the weekend of the ARRL EME event As a group we have tried with some success MS QSO and this helped lay the foundation for this weekend’s EME event.
EME is particularly challenging due to the great distances involved and extreme path loss of the signal after its travelled close on 500,000 miles! The equipment and format of the QSO is similar to MS, we used the WSJT-X 1.7 (currently in Alpha) and WSJT provided free from Joe Taylor K1JT website.
The weekend of the ARRL EME event was selected as it provided the best chance of working some of the EME “big guns”. Our equipment was quite modest by comparison, but included a
We found we could often decode signals, and even the thrill of decoding signals from the K2VEE in EM79 via the moon was incredible…then it happened.
We answered a CQ call by HB9Q and to our surprise they replied. This was our first and it turned out only EME QSO that weekend.
We continued to have quite a few MS QSO working Italy, Slovenia, Denmark and Norway and also a number of SSB contacts with 30 or so UK stations over the course of the weekend.
It is always nice to try a new mode and to succeed, you must never underestimate how difficult it is to achieve a QSO over that incredible distance. We achieved our goal of making an EME QSO, and regular decoding of signals via the moon. If this has inspired you to have a go I would encourage you to check out K4MSG guide to small station EME. Also have a look at W5UN monster EME array that has bagged him over 11,000 EME QSO !