Re: LF: EbNaut at 8270.01953125

[Andy Talbot <andy.g4jnt@gmail.com>]

Just a thought

The say GPSDO is delivering 16.384MHz

But there's a very good chance the GPSDO itself uses a DDS, so is subject to 32 bit tuning resolution.   Unless it has a 48 bit device or uses a  Fract-N approach

Andy  G4JNT

On 9 January 2018 at 19:15, Riccardo Zoli <riccardozoli80@gmail.com> wrote:

Hi Paul, Stefan, Andy, Markus....VLF

My specified QRG (printed with all decimals) is obviously theoretical. It permits, as Paul well explained, to achieve in days maximum reference phase precision for RX stations.

The value is obtained by a simple calculation:

my GPSDO is tuned at 16384.000 kHz and clocking a DDS programmed with a tuning dword = 8671744. DDS output is finally divided by 4 (SDR quadrature generator).

((16384000 / 2^32) * 8671744) / 4 =

8270.01953125

Thanks for reports.

This night, 5th attempt.

Same parameters, start time 18:30 UTC.

All the best

73 de Riccardo IW4DXW

Il 09/Gen/2018 18:29, "Paul Nicholson" <vlf0403@abelian.org> ha scritto:

It is good to know the frequency to within 1uHz for VLF
amateur radio.   A 1uHz error amounts to a 30 degree
phase error after one day, enough to significantly
affect the stacking of repeats.  Fortunately this is
quite easy to achieve with GPS timing.

Riccardo IW4DXW wrote:

> QRG: 8270.01953125
> 3 chars
> 60 sec/sym.
> coding 16K21A
> CRC 8
> duration: 12h 16'

>  start time 18:30 UTC

Todmorden (1412.5 km)
---------------------

 05/06 Eb/N0  +9.4 dB, S/N -24.7 dB/1Hz, phase -141.8 *Decoded*
 06/07 Eb/N0 +10.7 dB, S/N -23.4 dB/1Hz, phase   99.3 *Decoded*

 07/08 Eb/N0  +7.7 dB, H-field only,     phase  178.4 *Decoded*
 08/09 Eb/N0  +5.6 dB, S/N -62.5 dB/1Hz, phase  176.2 *Decoded*

Bielefeld (845.3 km)
--------------------

 05/06 Eb/N0 -3.7 dB, S/N -37.8 dB/1Hz, phase  -30.8;

 06/07 Eb/N0 +3.5 dB, S/N -30.6 dB/1Hz, phase -163.3 *Decoded*
 07/08 Eb/N0 +4.0 dB, S/N -30.1 dB/1Hz, phase  -66.4 *Decoded*
 08/09 Eb/N0 -4.2 dB, S/N -38.4 dB/1Hz, phase  -72.8;

Cumiana (370.5 km)
------------------

 05/06 Eb/N0 -7.7 dB, S/N -41.8 dB/1Hz, phase 102.4;
 06/07 Eb/N0 +1.2 dB, S/N -32.9 dB/1Hz, phase -54.9 *Decoded*

 07/08 Eb/N0 -2.5 dB, S/N -36.6 dB/1Hz, phase  20.5;
 08/09 Eb/N0 -7.6 dB, S/N -41.8 dB/1Hz, phase 102.0;

Warsaw (1035.0 km)
------------------

 05/06 Eb/N0  -4.9 dB, S/N -39.0 dB/1Hz, phase -62.3;
 06/07 Eb/N0 -15.6 dB, S/N -49.7 dB/1Hz;

 07/08 Eb/N0  -8.7 dB, S/N -42.8 dB/1Hz, phase -63.2;
 08/09 No data from rx site, uplink off;

--
Paul Nicholson
--

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