Sorry, I could not decode any message. There is some unknown timing delay from the PLL so I searched from 10:59:59.5 to 11:00:05 but could not decode anything. I tried combining E and H receivers but
W4DEX achieved another 'first' recently by sending a series of messages across the Atlantic at 8822 Hz which were successfully copied at Todmorden UK, range 6194km. Transmissions used coherent BPSK s
By reversing the modulation of Dex's Jan 1st transmission, the carrier is reconstructed. S/N and phase in in 1 hour (278uHz) steps: 00:00 to 01:00 11.6 dB -122.1 01:00 to 02:00 13.1 dB -119.4 02:00 t
Yes. To demonstrate... I mixed a locally (software) generated carrier into the audio recording of 1st Jan 00:00 to 07:00, placing it at 8823 Hz and setting the level to match approximately the averag
I made a spectrogram from the reconstructed carrier (the BPSK modulation removed by undoing the phase reversals). http://abelian.org/vlf/tmp/150106a.png The bin bandwidth is set to the bandwidth of t
DF6NM 10uW ERP at 8270 Hz at Todmorden, 1028 km. S/N and phase (lead) in 278 uHz (1 hour) averages Start --H-field-- --E-field-- 00:30 6.8 dB -51.2 -0.7 dB 01:00 4.7 dB -50.5 -7.3 dB 01:30 8.5 dB -49
Another spectrogram from 1st Jan. The BPSK signal from W4DEX was just strong enough to be visible at Forest VA (254 km) as a noisy band about 0.1Hz wide, http://abelian.org/vlf/tmp/150106b.png Bin wi
A very nice spectrum of the signal from DF6NM during the night of 2015-01-06. http://abelian.org/vlf/tmp/150107a.gif A mere 10uW produces 24 dB S/N at 1028km distance. The receiver is combining H-fie
No sooner said than done! Markus DF6NM just happens to have a servo controlled variometer which samples the radiated field and adjusts the tuning to maintain the phase of the transmission - even when
I second that. Very informative and I haven't seen this information collated anywhere else. Definitely one to save. CW by ear scores better than I would have guessed. Being a Morse code enthusiast I'
I have to agree with you that it can be appropriate sometimes. When measuring the performance of different convolution polynomial sets, I counted as payload all the bits going into the convolver beca
Yes it is always recording. I am looking for your message on all of the days you list. But, so far with no success. It is very strange because the signal seems quite strong. Sometimes you sent some c
Here is a modified version of wsend2v2 which has a test mode http://abelian.org/tmp/wsend2v2.exe (File size 20992 bytes). Enter a symbol period and press 'Test' and it toggles the relay on/off at the
I'm pleased to report that we got Uwe's BPSK transmission working, after some advice from Markus. The problem was that a phase correcting feedback loop was sampling the signal after the modulator, no
Uwe has been quite busy helping to test some BPSK comms with many transmissions during the last 2 or 3 weeks on 8270 Hz. The transmissions are not visible on a spectrogram, merely an imperceptible in
Yes, there is something wrong with the phase. The problem is at my end - looks like a software change to the receive timing about a week ago has produced a problem. There is, intermittently, a lot of
Some info on the SD-AUD20101. The chipset is Via Technologies, Envy VT1620A, Datasheet at http://abelian.org/tmp/vt1620a.pdf Sample rates 8k/sec to 96k/sec. Input is stereo, unbalanced, impedance abo
I tested weak signal detection. Measuring carrier S/N after a range of compression types and quality settings. Test carrier: 400 Hz; Noise: Additive white Gaussian; Bandwidth: 16.666 mHz (60 seconds)
I had to wait a while for a UK thunderstorm. I didn't get sharp resonances like those on Stefan's spectrogram, except for a short period about an hour after the storm. By that time it had moved away
