Hi all,
Maybe some of the stronger MF stations could provide a WSPR signal? In
the evening it would help as well...
I'm now running a local WSPR QRPPP test in heavy QRN. 2 WSPR instances
are running simultaneously, getting their signal from 2 different VAC
instances, from the same RF source. One is using a SpecLab's NB, the
other not.
Between the QRN bursts i can see a clear strong signal, about 20 dB SNR
in 1 Hz. The reports from the different WSPR instances are quite low
though!
One the WSPR instance having the NB in front of, the SNR reported is
arround -23 dB, the other does not decode anything!
Some QRO led to decodes on the WSPR instance which has no NB. The
reported SNR was 13 dB lower! The was in strong QRN.
Now the QRN level falls and the SNR difference varies a bit. It will be
interesting to see what the difference will be in a "normal" QRN
level...
See this for a better understanding:
https://dl.dropboxusercontent.com/u/19882028/MF/WSPR%20test.png
73, Stefan
Am 27.06.2015 15:21, schrieb DK7FC:
Hello Markus,
Am 27.06.2015 14:12, schrieb Markus Vester:
- WSPR: Last night, 21 of my
low-power WSPR transmissions were decoded simultaneously by DK7FC/p and
DK7FC. On average, the /p receiver had a 5.67 dB SNR advantage. For my
direction, the receive loop and the T antenna seem to have performed
similarly.
Today
between
11.08 and 11:24 I sent some more SNR sequences with higher
power (0.1 W EMRP), expecting a higher SNR difference in the lower
daytime background noise. However half of the transmissions were not
decoded on either grabber, and those that were picked up by both showed
only a small advantage. This is probably due to the strong QRN from
flashes from a nearby thunderstorm, which for some reason are heavily
affecting WSPR decodes. It might help to use effective noise blanking
in the SpecLab instance which is feeding WSPR. Anyway if the statics happen to ease off I will attempt
another daytime comparison later today.
I have now arranged VAC3 and a second WSPR-2 instance, appearing as
DK7FC/PNB (portable, noise blanker). The QRN is extreme now!!! It would
be very interesting to compare both WSPR instances now.
Now, better explained:
-The Raspi sends the vorbis data stream via WLAN to the web.
- SpecLab is reading the stream directly, generates the upper
spectrogram of the grabber page and feeds the stream in stereo mode to
VAC1.
- Another SpecLab instance reads the stream from VAC1 (reading from the
Raspi stream would mean another client for the Raspi, leading to twice
the CPU load, which is impossible) makes the frequency conversion
(474.2 kHz "dial") and SSB/USB filter and feeds the output to VAC2
- The first WSPR-2 instance (DK7FC/p) reads the input of VAC2
- All other normal spectrograms (QRSS-30...) are reading from VAC1
- Now that's new: Another SpecLab instance reading from VAC1 again,
preparing for WSPR, f-conversion, filter PLUS NB!, feeding to VAC3
- A second WSPR-2 instance reading from VAC3, appearing as DK7FC/PNB
Help, now the thunderstorm is coming closer!!!!! The grabber is just
white!
73, Stefan
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