Thanks a lot, Alex, for two reports in one - the traces on 137780 were actually the one-hour dashes of my "M".

 

Unlike for VLF, due to the frequency conversion in the receiver it is not easily possible to distribute a "one-fits-all" SpecLab USR for LF. In my case, the situation is further complicated by the dual-channel colour-DF scheme, and the odd way I lock my RX samplerate to an accidental (but deterministic) 876 Hz spur from the LO DDS. Here's an excerpt from a recent exchange with VE7TIL on the topic:

 

>> Scott, the slow SpecLab settings are fairly straightforward - I use 11025 Hz samplerate, complex decimation by 768, FFT size 32768, and 600 seconds per FFT. The center frequency and display offset will depend on your receiver's precise LO frequency (watch out for DDS rounding errors). Finally you will want to inject a known audio tone for samplerate tracking (eg. GPS-derived 5 kHz), or alternatively 1-pps pulses plus NMEA (which I haven't tried yet).

 

Best wishes,

Markus (DF6NM)

 

 

From: Alex K

Sent: Saturday, September 24, 2011 12:51 PM

To: rsgb_lf_group

Subject: LF: DK7FC, DF6NM, UA0AGC and very slow transmission on 137780

Hello LF, Stefan, Markus!
There are screenshots with signals DK7FC, DF6NM, UA0AGC and very slow transmission on 137780.
I would like to rx-experiment with such "QRSSSS" :) . Probably, someone has approaching *.usr file?
73 de rn3aus/Alex

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DF6NM QRSS-200 30sept 21z.png
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