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Re: LF: Heidelberg remote MF receiver

To: [email protected]
Subject: Re: LF: Heidelberg remote MF receiver
From: DK7FC <[email protected]>
Date: Sat, 27 Jun 2015 15:21:28 +0200
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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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