stlouisx50
Member
I just heard DTMF (hand pressed) tones on 131.950 mhz. This is not legal is it? If so, I have never heard it.
update: heard multiple times now
update: heard multiple times now
DTMF on aviation?
- Thread starter stlouisx50
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SELCAL - Wikipedia
ICAO Selcal - Signal Identification Wiki
ICAO Selcal (also known as AVCALL, ANNEX 10, or just SELCAL) is a HF/VHF aviation selective calling system used by ground stations to initiate radio communications with aircraft.
RFI-EMI-GUY
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Th OP heard hand pressed DTMF, Sel Call is pretty distinctive machine generated sequence.
stlouisx50
Member
The tones in the examples sounded different than the DTMF tones heard here in the USA . The tones I heard sounded like our telephone system in the USA. Is it possible this is something different or just a different sound because of a different type of system? Also the examples sounded like a computer dispatched rather than hand pressed.SELCAL - Wikipedia
en.wikipedia.org
ICAO Selcal - Signal Identification Wiki
ICAO Selcal (also known as AVCALL, ANNEX 10, or just SELCAL) is a HF/VHF aviation selective calling system used by ground stations to initiate radio communications with aircraft.www.sigidwiki.com
RFI-EMI-GUY
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It is certainly possible and legal that DTMF is being used on aviation frequencies.
Do any smaller airfields use DTMF tones to turn runway lighting on?
All the small ones within my reception range use a sequence of open carriers (PTT) to activate runway lights after hours. Like pressing the PTT button on the mic 5 times rapidly for example.
I do think the ARINC info is the correct answer in this case though.
All the small ones within my reception range use a sequence of open carriers (PTT) to activate runway lights after hours. Like pressing the PTT button on the mic 5 times rapidly for example.
I do think the ARINC info is the correct answer in this case though.
It's legal to use DTMF as others have said. Some aircraft operators have installed a handheld mic with the DTMF number pad. Colins (Formerly ARINC) used to offer a self service phone patch system that relied upon aircraft using a DTMF numberpad.
Information on the DTMF system that Collins used to offer is found here on PDF page 10, section 3.4.1
Information on the DTMF system that Collins used to offer is found here on PDF page 10, section 3.4.1
Not that I'm aware of. The tech is certainly there however clicking the PTT several times in a row is good enough.
nd5y
Member
I've heard that too but it's been a while. 131.95 is probably American Eagle depending on where you are. It sounded to me like they use hand-dialed telephone type DTMF tones (not to be confused with two-tone paging type ARINC selcal codes) to activate certain base stations the same way that some railroads do.
No. Most aircraft do not have DTMF capabilities.
To add to this, I'm at my second airline right now, at my first one none of our airplanes had DTMF capability. At my current airline some of our airplanes have DTMF keypads on one of the handheld microphones, but we currently don't use the DTMF capability. All you need is a handheld mic with the keypad to plug 'n play.
With all that said, other airlines may use DTMF. I am by no means trying to say no one uses it. Other airlines have their own nationwide radio network (Such as Delta's Atlanta Radio) and may use DTMF, I don't know for sure.
Exactly! Some planes definitely have the capabilities, but the vast majority do not. Also need to remember, it is not the airlines (generally) that are going to be using pilot controlled lighting in the first place. It's going to be your smaller GA aircraft.
tiniancrab
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In addition to SELCAL tones, you might hear someone keying regular telephone tones as well. My former airline subscribed to Jetcomm, which had lines to dispatch and MedLink accessible with certain codes.
We used to use DTMF many years ago. we would communicate with the company with these. They called them dialup sites. You would have to key up and enter in a few numbers specified on the chart and that would connect you to your dispatcher or whoever you needed. Not sure why some places used this and most did not. I haven’t seen a DTMF mic at my current airline. The CRJ had a DTMF mic at my last airline but we didn’t use it a whole lot, but I guess someone still uses it
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wrees
Member
I agree, it is 100% legal to use DTMF. Electrovoice make the DTMF handheld mics in the fleet of aircraft i work on. It is for an SCOM system called AIR-LINK which is basically a radio to land phone link using AM airband frequencies, same as ham radio phone patch. DTMF is covered from the FAA in a Technical standing order TSO C-58a. Even though i am in Canada the FAA TSO's still apply. Hope this helps.
