If you choose to use the NEO7 fractional pll output directly, then pick
frequencies which are 48MHz/N where N is an integer. This will lead to a
much cleaner signal. 8.27015kHz is one possibility (48000kHz/5804).
Another option is to use Paul's ebsynth, and feed it a clean reference
frequency from the NEO7. I use a 20kHz reference (48000/2400). This can
generate an arbitrary frequency.
VY 73
Jacek / SQ5BPF
On Sat, 7 Oct 2017, Markus Vester wrote:
Date: Sat, 7 Oct 2017 17:57:36 -0400
From: Markus Vester <[email protected]>
Reply-To: [email protected]
To: [email protected]
Subject: Re: LF: VO1NA in Todmorden on 8270 Hz
Hi Joe,
good to know that you are on air again. The DL0AO grabber in Amberg (East Bavaria)
includes your frequency in one of
the 31 uHz instances.
> Yes, the high wire for 630m (~5 W EIRP) and the low for 36000m.
Shouldn't that be the other way round, maximizing the important VLF radiation ?
;-)
> Yes, pps and NMEA to SpecLab but evidently no discipline yet
Getting the SpecLab samplerate detector to work will lock your frequency but
not the phase. To avoid the risk of
phase jumps due to soundcard glitches or buffer underruns, I would then strongly
recommend to set up the software PLL
with audio feedback from a pickup probe. This method also has the advantage of
maintaining absolute
phase despite variations in the antenna circuit. But I have to admit that setting up
SpecLab that way is a bit more
involved, especially when you also want to apply PSK modulation for EbNaut.
With the programmable ourtput frequency from the NEO7, you may have two
other, simpler options:
- You could tell the NEO to output the desired transmit frequency directly. For
EbNaut, you can later add the
traditional XOR or balanced mixer circuit.
- You could use the NEO with high frequency output as a clock source for your
DDS. EbNaut could be generated either
by XOR or by manipulating the DDS phase word.
Best wishes,
Markus
-----Ursprüngliche Mitteilung-----
Von: jcraig <[email protected]>
An: rsgb_lf_group <[email protected]>
Verschickt: Sa, 7. Okt 2017 18:46
Betreff: Re: LF: VO1NA in Todmorden on 8270 Hz
Paul Markus and Group,
Thanks Paul for the reports. The radiation gives more gratification than the
efforts to get a stable carrier.
On Sat, 7 Oct 2017, Markus Vester wrote:
> Great result!
Truly astounding that Paul can receive 10 uW at 3600km with 10+ dB S/N.
> Hmm I thought that VO1NA had been on 477 kHz during those nights. Joe are you
transmitting MF and VLF
simultaneously, on two antennas?
Yes, the high wire for 630m (~5 W EIRP) and the low for 36000m.
> Do you already have GPS lock available on 8.27 kHz?
Yes, pps and NMEA to SpecLab but evidently no discipline yet. The pps pulse
looks strange on the SL scope and there
are 'PPS zero-crossing too
flat' debug errors on SL SR correction. This is all the NEO7M seems willing to
provide at the moment; connecting the
raspi3 to the tiny USB
pins on the NEO7M was fun, but otherwise unproductive. I'm hoping it's possible
to send commands directly to the
neo7m via usb without a special chip.
RSNTP is running on the SL pc.
73
Joe
>
> 73, Markus
>
>
>
> -----Ursprüngliche Mitteilung-----
> Von: Paul Nicholson <[email protected]>
> An: rsgb_lf_group <[email protected]>
> Verschickt: Sa, 7. Okt 2017 10:36
> Betreff: LF: VO1NA in Todmorden on 8270 Hz
>
>
>
> VO1NA on 8270.00709 is a good nighttime signal at Todmorden
> recently. Here are the last three night's spectra in 34.72 uHz
> (8 hours 23:00 to 07:00 UT) using combined E-field and H-field.
>
> http://abelian.org/vlf/tmp/171007b.gif S/N 12.6 dB
> http://abelian.org/vlf/tmp/171007c.gif S/N 14.5 dB
> http://abelian.org/vlf/tmp/171007d.gif S/N 11.4 dB
>
> Not bad for 8uW ERP at range 3575 km and an undisciplined
> OCXO.
>
> --
> Paul Nicholson
> --
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