Hi Stefan:
I think I know how to configure clipping in SL (done it before) but
by all means send me your usr - can only be helpful. I've had good
results with software clipping when I recorded the raw digitized data
first then decided where/how clipping should occur after looking at
it. Too hard to predict optimum clipping settings for a long
overnight run. I didn't try recording last night: SL probably
records incoming soundcard data before its internal sample rate
correction is applied, so that would raise another issue. I suppose
I could add a sample rate correction step to the software I use for
off-line processing, then we wouldn't need SL at all, hi! Even
uncorrected SC sample rate is likely stable enough for QRSS-60 stuff
anyway, especially after a short warmup. With the kind of band noise
we had last night I don't think clipping would have been
beneficial. The Rx here is a TS-850 (master clock derived from GPS
std), using CW mode 500-Hz IF filter with audio out at nominally
800-Hz (actually, when the TS-850 is set to receive 136.172 Khz using
1-Hz tuning steps an incoming carrier at that frequency will produce
an audio output tone at 799.944 Hz). The external GPS-monitored freq
std runs 24/7. Main advantage is a Rx that's instantly on-frequency
and doesn't drift even right after turn-on. Last night I had the Rx
AGC enabled so lots of compression due to almost continuous static
crashes. I leave the RF gain at max when I go to bed because band
noise often dies down at some point. I was using a complex FFT with
center frequency set to 800 Hz. For some reason SL didn't like it
when I tried to enter the more precise frequency and rounded it to
nearest Hz. I also have an SDR-IQ here which might be useful at 136
Khz but didn't see your announcement in time. The SDR-IQ isn't
locked to an external reference so for long term carrier detection
the TS-850 is preferable. I'll run the grabber again tonite. What
time will you start Tx?
73,
Bill VE2IQ
At 09:51 AM 9/7/2011, you wrote:
Hi Bill, again,
Fine! So you will run the grabber tonite again? Looking forward to that!
If the noise was "awful" (one can even see a broad band noise during
that time which must be local) and you use no noise reduction so
far, we will surely gain some dB soon :-)
Yes, the trace was pretty exactly on the QRG and there were no other
traces like that on the whole spectrogram :-)
About noise reduction: If you want, i can send you a usr file where
you can see how to arrange that if you don't know how. Where does
the AF comes out on your RX (e.g. 137 kHz = 1 kHz) ? What is the RX?
A HF TRX with a SSB filter?
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