Tones heard on MWARA HFNAT-B?

[vannossc]

Can anyone advise what are the two tired tones are I hear at the end of many communications on MWARA HF NAT-B (5616/8864 kHz in this case)? Hearing them very weakly so barely can make out the conversation. Last words are a phonetic code then the tones.

Thanks!

Scott

 

[Saint]

Can anyone advise what are the two tired tones are I hear at the end of many communications on MWARA HF NAT-B (5616/8864 kHz in this case)? Hearing them very weakly so barely can make out the conversation. Last words are a phonetic code then the tones.

Thanks!

Scott

SELCAL
SELCALL - Search (bing.com)
Steve

 

[vannossc]

SELCAL
SELCALL - Search (bing.com)
Steve

Thank you!!

 

[n6hgg]

Can anyone guess what mode they transmit the secall in? It doesn't work in SSB mode. They broadcast it in a.m. because they need to maintain the tone integrity, and broadcasting it in single Side Band would mean that radios that are a little bit off frequency would hear a different tone. So all the voice communications are in upper side while the selcall transmission AND reception is in a.m.

 

[Saint]

When listening to the MWARA frequencies use USB for voice and selcall
Steve

 

[Saint]

This ia a short video of decoding Selcal

Steve

 

[majoco]

https://www.sigidwiki.com › wiki › ICAO_Selcal

The ICAO Selcal signal itself is USB modulated with a full carrier. The radio transmissions that follow a Selcal are typically USB modulated voice without a carrier.

 

[VK3RX]

Having used HF extensively to communicate with aircraft in my early ATC days, I can honestly say that I never encountered either an aircraft or ground station that seemed to be "off frequency". Our consoles weren't equipped with a "clarifier", so such stations were either spot on or within a few Hz not enough to be noticable or a problem.

Aero compliance with technical standard orders is a wonderful thing

broadcasting it in single Side Band would mean that radios that are a little bit off frequency would hear a different tone.

 

[invergordon]

Having used HF extensively to communicate with aircraft in my early ATC days, I can honestly say that I never encountered either an aircraft or ground station that seemed to be "off frequency". Our consoles weren't equipped with a "clarifier", so such stations were either spot on or within a few Hz not enough to be noticable or a problem.

Aero compliance with technical standard orders is a wonderful thing

That is my experience too although only from an enthusiasts point of view. With modern SDR I seldom if I ever have had to tune the AF to receive good copy of voice or SELCAL tones into MultiPSK.

 

[Saint]

I also have had no problems decoding selcal tones with Multipsk I just stay on the frequency I listen to the aircraft in USB and it decodes perfectly
Steve