SAQ Grimeton (Sweden) today - Sainte-Assise


Patrick Lindecker
 

Email supposed sent yesterday…

 

De : Patrick Lindecker [mailto:f6cte@...]
Envoyé : dimanche 4 juillet 2021 12:14
À : 'Patrick Lindecker'
Objet : SAQ Grimeton (Sweden) today - Sainte-Assise

 

Hello to all,

 

Today I tried to hear SAQ on 17200 Hz. I had no time to prepare a good receiver and I did not receive SAQ, but it was interesting. Normally it might be heard  VVV VVV VVV DE SAQ SAQ SAQ in CW at about 17 wpm.

The receiver was just a resonant circuit adjusted on 17200 Hz followed by an audio preamplifier, the signal at the preamplifier output being directed towards the sound card input (microphone) for processing by Multipsk. The problem is that individually, all elements of the receiver seem good, but when I have connected  the resonant circuit to the preamplifier, this one, very strongly, damped the resonant circuit.

 

However, I received very well a transmission which seems  MFSK16, around 21 kHz. Apparently, it must be a transmission from Sainte-Assise (near here), which communicates with diving submarines.

 

Below, a snapshot (note that the frequency is shifted by 7 MHz). Note that the bandwidth is between 15.5 to 18.5 kHz (and not ideally from 17.1 to 17.3 kHz), due to the damping on the resonant circuit. It can be seen the 21 kHz transmission despite the resonant circuit because the transmission is very powerful.

The reception is symmetrical on the SdR waterfall because it is received a real signal and not an I/Q SdR signal:

Sainte-Assise.jpg

 

SAQ will be for the next time.

 

73

Patrick