Anyone got a circuit to decode HF Selcal. Or know of a inexpensive decoding equipment?
HF Selcal decoder
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majoco
Stirrer
Quite a few errors in the "SELCAL" video. On first contact with the area HF ground station inbound from another area or outbound, the aircraft has to test it's selcal equipment, CPDLC equipped or not. The aircraft calls the ground station with it's flight number and altitude and maybe a weather report. The ground station replies as having received the report and gives a "Selcal Check" - the aircraft has to respond with "Selcal check OK" or similar - the ground station responds with "Received" or "Continue with CPDLC". Often when the aircraft responds with "Nil Selcal" the pilot has forgotten to reset the Selcal from the previous call or check! A quick push of the "Selcal reset" to re-arm and the next Selcal is successful - strange that! Every aircraft has its unique Selcal tones and after a while the crew perk up when 'their' tones are received - much like when receiving your callsign in morse code - the tones are louder than the voice. The alarm in the cockpit is a light and a chime and the pilot on radio duty replies "Flight number xxx answering Selcal" - the ground station then responds with the message. There is some confusion - the aircraft dos not call the ground station with Selcal and indeed can not - the ground station operator is listening all the time on it's primary or secondary frequency - often the noise level is very low as the receiver site is chosen very carefully and has switchable antennas.
ka3jjz
Wiki Admin Emeritus
MultiPSK can decode Selcalls…..Mike
I am looking for a stand alone hardware decoder. Or a circuit to homebrew one.
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majoco
Stirrer
I see no point in re-inventing the wheel! Plenty of the old Motorola selcal decoders on various sites for not too many beer vouchers - although they probably won't tell you what you need to know - and there's more than 8 tones in use these days as the stability of the HF SSB receivers has improved and the filters in the decoders are easier to implement with solid state devices rather than the glass bottles. I've never looked inside the M'rola decoders but I do recall that some of the manufacturers used tuned reeds like a harmonica to filter to tones. Of course if you got one of these they would only indicate when the four tones they were set up for would set it off. I don't see the point of such a project, even a relatively computer program could decode the tones and indicate what they were, but then what? You would have to search through a list of every HF equipped aircraft and co-relate the tones to the registration, then maybe to the operator and then search the timetables to see where the aircraft was and so on. By the time you've done all that for one aircraft, it's landed, spat out all the punters, loaded up some more, taken off and disappeared into the sunset......
PS - the selcal tones are tied to the aircraft at building and never change - not like the ACARs squawk codes - as I said there used to be only 8 tones but that turned out not to be enough so there was some duplications. They tried to keep the dupes at other sides of the world but HF radio doesn't care! I've had selcal chimes go off on the ground in the evening and listened to an aircraft in mid Atlantic being called from Shannon!
PS - the selcal tones are tied to the aircraft at building and never change - not like the ACARs squawk codes - as I said there used to be only 8 tones but that turned out not to be enough so there was some duplications. They tried to keep the dupes at other sides of the world but HF radio doesn't care! I've had selcal chimes go off on the ground in the evening and listened to an aircraft in mid Atlantic being called from Shannon!
zytorx
Member
I can share airnav selcal decoder software
invergordon
Member
Here's my take on SELCAL decoders, I use MultiPSK only because it provides the best user experience despite it's GUI downfall:
MultiPSK - the best of the bunch, but a visual nightmare and too much other stuff included. It does take the decoded SELCAL tones and run them through a user supplied list of codes to decode to an airframe. After an airframe is identified by the user as a possible solution (some route knowledge required here) from any duplicates (all depends on how many in your list) it then searches Flightaware for what flight the airframe may be currently flying. If found, you correlate that flight to the frequency and/or ground station your listening to and decide if it's a good match. Powerful, but only for Windows and limited if used using Wine on Linux. Has the 16 tones labelled by tick marks on a pseudo AF display and these tick marks can be adjusted to line up with the received audio if your receiver output is slightly 'off'.
AirNav SELCAL Decoder - Average ability to decode (my perspective!) but has a terribly slow method of adding new SELCAL codes and aircraft details and I feel it is really unmanageable this day and age, very proprietary. Windows only and probably not for Windows 10.
ComTekk AvCall - Appears to take a lot of audio input, more than my PC can provide so I've never able to decode anything. It does have a user configurable CSV file for decoding to airframe.
Scorcerer - Decodes on the voice audio regardless of the threshold set and streams two digit decodes on the same line so difficult to know if the codes relate to audio or SELCAL tones. No user database.
Wavecomm - Too expensive
Hoka Code 32 - Too expensive
Apart from these I'm not aware of any other software SELCAL decoders, free or paid.
While MultiPSK offers the best all round product at a cheap outlay, I'd like to see some sort of hardware or software decoder designed to provide a user experience for the #AvGeek and #HFAero community.
MultiPSK - the best of the bunch, but a visual nightmare and too much other stuff included. It does take the decoded SELCAL tones and run them through a user supplied list of codes to decode to an airframe. After an airframe is identified by the user as a possible solution (some route knowledge required here) from any duplicates (all depends on how many in your list) it then searches Flightaware for what flight the airframe may be currently flying. If found, you correlate that flight to the frequency and/or ground station your listening to and decide if it's a good match. Powerful, but only for Windows and limited if used using Wine on Linux. Has the 16 tones labelled by tick marks on a pseudo AF display and these tick marks can be adjusted to line up with the received audio if your receiver output is slightly 'off'.
AirNav SELCAL Decoder - Average ability to decode (my perspective!) but has a terribly slow method of adding new SELCAL codes and aircraft details and I feel it is really unmanageable this day and age, very proprietary. Windows only and probably not for Windows 10.
ComTekk AvCall - Appears to take a lot of audio input, more than my PC can provide so I've never able to decode anything. It does have a user configurable CSV file for decoding to airframe.
Scorcerer - Decodes on the voice audio regardless of the threshold set and streams two digit decodes on the same line so difficult to know if the codes relate to audio or SELCAL tones. No user database.
Wavecomm - Too expensive
Hoka Code 32 - Too expensive
Apart from these I'm not aware of any other software SELCAL decoders, free or paid.
While MultiPSK offers the best all round product at a cheap outlay, I'd like to see some sort of hardware or software decoder designed to provide a user experience for the #AvGeek and #HFAero community.
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