Hi Stefan, Markus, Domenico, LF
Vy strong here (as usual) in JN64bw, dr Stefan.
Good decode: there is only a little phase rotation and I see you about
6.3mHz lower than your nominal QRG.
All the best
73 de IW4DXW Riccardo
p.s.: congrats for your efforts and fantastic results in VLF activity.
Keep up the good work!
2017-06-19 22:42 GMT+02:00 DK7FC <[email protected]>:
> Hello Markus, Domenico,
>
> Ket's just play arround a bit more instead :-) It was such a nice day here,
> time for another message :-)
>
> f = 137.53 kHz
> Start time: 19.Jun.2017 20:40:00.3 UTC
> Symbol period: 1 s
> Characters: 40
> CRC bits: 16
> Coding 4K19A
> Duration: 18m, 16s
>
> 73, Stefan
>
>
>
> Am 19.06.2017 17:46, schrieb Markus Vester:
>
> Hi Stefan,
>
> the frequencies of recent detections (e.g. IW4DXW) on our two opds grabbers
> seem to be within a mHz, so your 10 kHz derived receive LO should be ok.
> Could it be that the strong LF transmit signal is interfering with either
> the GPS itself or the 1pps samplerate detector?
>
> My opds image currently shows a zoomed section around on 137517.000 which
> you might use to check your TX frequency.
>
> Domenico mentions a possible problem when using synced resampling in the TX
> instance. I haven't run into that yet as I'm currently not using resampling,
> neither for TX or RX instances (only 1pps phase-lock but no resampling). The
> disadvantage on RX is that the frequency offset from the FFT center
> frequency is not tracking samplerate deviations, but this is only a small
> effect (e.g. about 30 uHz error 30 Hz offset and 1ppm drift).
>
> One advantage of SpecLab TX with audio feedback is that the phase can
> recover from audio dropouts on the ADC and DAC side. This might potentially
> become a problem for EbSynth on a RasPi with USB soundcard.
>
> Best 73,
> Markus
>
> -----Ursprüngliche Mitteilung-----
> Von: DK7FC <[email protected]>
> An: rsgb_lf_group <[email protected]>
> Verschickt: Mo, 19. Jun 2017 16:56
> Betreff: Re: LF: EbNaut test
>
> That is strange indeed. Maybe something is wrong here? Maybe the old GPS
> module is not running properly? I had to replace a mains socket recently and
> had to shut down the complete station for that.
> I would like to run a carrier transmission. Could someone of you check it
> for frequency accuracy? Or we do it the other way. Domenico, your OP32
> signal has always been very accurate, i remember 137485.000 Hz. Can you run
> a transmission so i would see the same offset here maybe? Or maybe Markus,
> or Riccardo?
>
> 73, Stefan
>
> Am 19.06.2017 16:27, schrieb Markus Vester:
>
>>> Where does that -3.4 mHz offset come from?
>
> That's strange. I observed exactly the same frequency offset here
> (137499.9825 Hz RX LO + 30.0141 Hz offset). On the other hand, your TX
> signal generation "should" provide a GPS-accurate frequency.
>
> The 0.3 s time lag is expected due to soundcard DAC latency.
>
> Best 73,
> Markus
>
>
> -----Ursprüngliche Mitteilung-----
> Von: DK7FC <[email protected]>
> An: rsgb_lf_group <[email protected]>
> Verschickt: Mo, 19. Jun 2017 15:44
> Betreff: Re: LF: EbNaut test
>
> Hi Domenico,
>
> Thanks for the detailed report and the EbNaut decode over 1159 km. It was
> still in daylight, so not bad for LF in mid June and a 376 second long
> message...
> Where does that -3.4 mHz offset come from?
>
> Well, i realised that i don't even need to build the XOR gate circuit. I
> simply used the PC that generates EbNaut for VLF, i.e. SpecLab, which has a
> PPS+NMEA input. I choose a frequency of 12530 Hz. Then i built an LF
> up-converter (in 2011) that has a LO of 125 kHz. So i come out on 137.53
> kHz. That 125 kHz LO frequency (4 MHz xtal down-divided) is PLL locked to
> the 10 kHz ref output of the old Jupiter GPS, which is running here since
> 2010. The 10 kHz and the 125 kHz are also used on the RX side. So i can
> generate stable signals on LF...
> It seems it works :-)
>
> 73, Stefan
>
>
> Am 19.06.2017 14:59, schrieb Domenico IZ7SLZ:
>
> Hi Stefan, LF
>
> as i suspected, i found my linux-pc storage hard disk full. A new 1 TB HD
> is now in order.
> So unfortunatly i can't give you an EbNaut report obtained using full
> vlfrx-tools programs.
>
> OPDS SL session has recordered a file witch covers your 16:30 EbNaut
> transmission. I got a nice decode using almost the same offsets found by
> Markus DF6NM.
> I have tried to use also linux ebnaut, after converting the wave file with
> following shell script:
> ------------------
> #!/bin/bash
> sox 06181637.wav -t dat -|
> sed '/;/d' |
> ebnaut -v -dp4K19A -F29.9966 -N10 -S1 -r111.11111 -c2 -L200000 -PS -v
> -T724.5 # |tee dk7fc.txt
> -------------------
>
> But it gives, of course, almost the same results.
>
> At the link http://qsl.net/i/iz7slz//DK7FC/ i have uploaded FFT raw and
> wave files, in case someone wants to try the decoding.
>
> So Stefan, congratulations for your first LF-Ebnaut transmission. Can you
> tell us how did you generate the signal ?
>
> There is a very easy and cheap method actually in use by Riccardo IW4DXW
> and Tony IK1HGI for generating a coherent carrier for EbNaut.Congrats to
> Riccardo for this nice idea.
> They are using directly the timing pulse TP5 output of the neo-8 GPS . In
> fact this timing port (TP5) can be reprogrammed up to 5 MHz.
> The BPSK modulator consist of an XOR port in between the GPS TP5 output and
> the PA driver. Cool !
>
> 73 Domenico, IZ7SLZ
>
>
>
>
>
>
>
>
> On 18 June 2017 at 23:44, DK7FC <[email protected]> wrote:
>
> Thanks Markus, nice. We could exchange 1000 characters in 2 minutes, if the
> Eb/N0 calculation is correct :-)
> Maybe i will try another one with Domenico when he is back. And is RN3AUS
> reading this email?
> Is someone else interested in an LF EnNaut test, if the equipment is
> available,maybe W1TAG?
>
> 73, Stefan
>
>
> Am 18.06.2017 22:07, schrieb Markus Vester:
>
> Hi Stefan,
>
> a fine and error-free decode, best with 0.3 s extra delay. A phase glitch
> occured here near the middle, presumably on the receive side.
>
> Best 73,
> Markus
>
>
>
> -----Ursprüngliche Mitteilung-----
> Von: DK7FC <[email protected]>
> An: rsgb_lf_group <[email protected]>
> Verschickt: So, 18. Jun 2017 18:35
> Betreff: Re: LF: EbNaut test
>
> PS: This time 100 Hz higher
>
> Am 18.06.2017 18:28, schrieb DK7FC:
>
> Hello Markus,
>
> Oh, you are right. Same message on 16:30 utc. ..
> I hope it works...
>
> 73, Stefan
>
> Am 18.06.2017 16:56, schrieb Markus Vester:
>
> Hi Stefan,
>
> I'd like to try. But the QRG 137.43 kHz was below my opds capture range
> (137.45 to 137.55 kHz).
>
> 73, Markus
>
>
>
>
> -----Ursprüngliche Mitteilung-----
> Von: DK7FC <[email protected]>
> An: rsgb_lf_group <[email protected]>
> Verschickt: So, 18. Jun 2017 16:47
> Betreff: LF: EbNaut test
>
> Hi LFers,
>
> My first EbNaut message is running at the moment. Not sure if the timing
> and keying is OK. Could someone check if it can be decoded? Don't make a
> secret out of the message.
>
> Parameters: 4K19A, 1sec, 10 char, CRC16, Start:14:36 UTC (maybe there is
> a timing offset between +-1 sec? pse report).
>
> 73, Stefan
>
>
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