Re: LF: Naive WSPR15 question

[Markus Vester <markusvester@aol.com>]

If you want to use SpecLab as a frequency doubler, you could simply employ the "amplitude demodulator" e.g. in the L1-L2 blackbox. With high enough output bandwidth (> 5000 Hz), it acts as a full-wave rectifier, producing DC, 2xf and higher even-numbered harmonics. These can then be filtered by a bandpass filter around 2xf, and also frequency shifted before or after doubling.

BTW I have employed this scheme to frequency-double the MSK-signal from NWC, producing a pair of spectral lines whose absolute phase is plotted on the DL0AO VLF-grabber.

Best 73,
Markus (DF6NM)

-----Ursprüngliche Mitteilung-----
Von: DK7FC <selberdenken@posteo.de>
An: rsgb_lf_group <rsgb_lf_group@blacksheep.org>
Verschickt: Di, 5. Feb. 2019 21:06
Betreff: Re: LF: Naive WSPR15 question

Hell Markus, LF,

While walking to the tree today (which takes at about 30 minutes, you know) i had a thought/idea how the double shift keying for WSPR could be made:
Let's assume the frequency (audio) is known to +- 200 mHz maybe, let's say 1500 Hz. Then, would it be possible to use a SpecLab instance and measure the frequency arround 1500+-3 Hz which has the highest signal level? This way one could identify which of the 4 FSK frequencies is getting out of the WSPR software in that moment. Then, could we say, using the conditional actions, if frequency is higher than x and lower than y, that this is identified as '2' (1, 2, 3, 4). And then, if '2' is identified, use the signal generator and transmit on another frequency, which is then at twice the shift frequency from the center. All in all, just 4 lines in the conditional actions window (maybe adding a minimum signal level is required also to give a 'true').
So, determine the input frequency and generate another one using the internal signal generator?
This must be a fast running spectrogram / FFT, to be fast enough but it should be no problem. There must be no significant drift of the TX though but that could be possible too.
I expressed myselfe a bit difficult but i guess you know what i mean. But i try to make it a bot more clear (for me too ;-) ):
>From the file 'wsptones.txt' i got the information that
0= 1497.803 Hz
1= 1499.268 Hz
2= 1500.732 Hz
3= 1502.197 Hz
The difference between 2 steps is 1.465 Hz, obviously.
So, if the detected frequency from the input is higher than 1500 Hz and lower than 1501.465 Hz, then this is '2'. And then, the signal generator must produce a frequency of 1501.465 Hz instead, which is '2' with twice the offset from the center frequency. And so on...
If this output signal is upconvertred by 272 kHz and then sum is divided by 2, we should come out at the normal WSPR spacing at 137.5 kHz.
This would then also work without the slow WSPR tool and should also work for WSPR-15...

73, Stefan



Am 04.02.2019 22:08, schrieb Markus Vester:

Hi Stefan, Chris,

in principle yes… (R. Eriwan)

The old tools from 2012 are here 
http://df6nm.bplaced.net/wspr/slowWSPR.zip
But they used a homemade 16-bit-utility "waitraster" for timing, which is no longer supported by 64-bit Win-7 and Win 10. This can be replaced by simple DOS commands, which has so far been implemented for receiving WSPR-15
https://klubnl.pl/rsgb_lf_group-archives/html/rsgb_lf_group/2018-11/msg00318.html
but not yet for transmitting. So a little more work will be needed.

On the other hand, I'm asking myself why so many people still insist on having dividers before their PA's. It only makes life more difficult, and undermines coherent EbNaut or Opera signal transmissions. 

Best 73,
Markus (DF6NM)

-----Ursprüngliche Mitteilung-----
Von: DK7FC <selberdenken@posteo.de>
An: rsgb_lf_group <rsgb_lf_group@blacksheep.org>
Verschickt: Mo, 4. Feb. 2019 21:11
Betreff: Re: LF: Naive WSPR15 question

...i checked some files from the slow_WSPR tool. I think i would be able
to solve the problem. Maybe Markus likes to confirm that this could work
(getting a factor 2 in the frequency shift)?
Chris, it would then be worth to try the normal tool first.

73, Stefan

Am 04.02.2019 20:25, schrieb DK7FC:
> Hello Chris,
>
> For a clever person it is very easy :-)
> It will depend on which way you want to generate WSPR.
> Here, for example, i have a Raspi which generates my WSPR (2) for MF.
> I modified the c source code so that the frequency is 4 times higher
> and the frequency shift is 4 times higher too. In my PA, probably like
> in yours, there is a frequency divider using CD4013 ICs which
> reproduce the desired frequency and frequency shift. Of course this
> can be done with a factor 2 too.
> For Windows solutions, there is DF6NMs tool for slow WSPR which works
> very reliable here, for WSPR-2 and WSPR-15. I'm sure this can be
> modified for twice the frequency shift but then you will need an
> upconverter to convert it to LF or MF...
>
> 73, Stefan
>
> Am 04.02.2019 13:21, schrieb Chris Wilson:
>>
>> Hello  LF,
>>
>>    A  naive  question  re  WSPR15  please?  Assuming the source code is
>>    available  how  hard  would  it  be  for  a  clever person to add X2
>>    functionality to it? Thanks.
>>
>