4.003 Mhz data signal

[alok]

I hear a strong data signal in the southeast at night on 4.003 MHz, noted around 8 PM but it seems to be there at other times too , sounds like " a fast " RTTY, what is it ?
I tried decoding it but nothing.

 

[mancow]

I think it's military. It runs continuously. Maybe like an orderwire on HF.

 

[ka3jjz]

I can't come up with it definitively using the UDXF logs, but 'fast RTTY' might be STANAG4481 (STANAG modes are often used by NATO forces around the world, but many also originate here in the States) which is normally encrypted. You'll never break it - and if you do don't tell anyone...Mike

 

[dlwtrunked]

I hear a strong data signal in the southeast at night on 4.003 MHz, noted around 8 PM but it seems to be there at other times too , sounds like " a fast " RTTY, what is it ?
I tried decoding it but nothing.

I hear a strong data signal in the southeast at night on 4.003 MHz, noted around 8 PM but it seems to be there at other times too , sounds like " a fast " RTTY, what is it ?
I tried decoding it but nothing.

4005 kHz USN transmitter at USAF Davidsonville, MD (encrypted 75 Bd 850 Hz shift)

 

[ka3jjz]

(heh) It's in my neighborhood - skips right over me...anyway, I should have recognized this as one of the several freqs identified in this post...

https://forums.radioreference.com/threads/undecodeable-signals.381373/

Mike