Re: R: Re: VLF: EbNaut message over 2877 km, DK7FC to RC4HAA

[Domenico IZ7SLZ <iz7slz.domenico@gmail.com>]

Hi, Stefan

Thanks for reply.

Yes linux pc is using 'vttime' to calibrate soundcard and to timestamp the audio samples.

So SpecLab receives via vorbis stream, calibrated audio.

 Yes, you are right, the alpha1 looks very strange but note that it is observed at 42 uHz resolution.

Most probably i have to deal with 1pps pulse shaping to improve performance of vttime. Maybe it works ok in my LF experiments but need some adjustment for VLF.

73, Domenico

On 9 Nov 2017 18:33, "DK7FC" <selberdenken@posteo.de> wrote:

Hi Domenico,

Thanks for your continued interest in the very low frequencies :-)

Are you using vttime to correct the sample rate? Or are you doing it in SpecLab? The Alpha trace looks maybe a bit unstable(?).
If you have a second PC, you could try to make a local transmission, just with a piece of wire, and then checl if you can decode it. It would be a first check of the system.

I'm looking forward to the AMF!!! :-)

73, Stefan

Am 09.11.2017 17:59, schrieb Domenico IZ7SLZ:

Hello VLF,

First of all, congratulations to Stefan, Paul and all OM partecipating at these experiments for the successfull results.

I'm trying to receive some VLF Ebnaut, in Apulia -South Italy, till now without joy.

Unfortunatly, the remote location at Aunt Melina farm (AMF) , 5 km away from my city is not yet ready. 

In the same time i'm trying, in my urban usual location, to streaming (locally) the audio captured from linux pc using vlfrx-tools utilities.

Vorbis stream sent by vtvorbis is received via lan from Spectrum Lab on Xp PC. A 42 uHz grabber is running since 3 days now.

http://qsl.net/iz7slz/OPDS/grabber.jpg

Linux pc is also recording the raw audio using vtwrite. 

So i'm making some attempts to decode Dk7fc ebnaut trying to guess the best parameters for vtblank.

I have some question for Paul:

Can you suggest and give some indications how to stack raw audio of two or more different days using vlfrx-tools?

Some advice for the vtblank configuration? 

I'm using version 07p.

...and questions for Joe VO1NA:

Can you specify again the start time, frequency and all parameters of your EBNAUT transmissions? Some long carrier has been transmitted by you and in which hour?

Thanks in advance. 

73, Domenico /IZ7SLZ

On 9 Nov 2017 17:28, "Paul Nicholson" <vlf0403@abelian.org> wrote:

Stefan wrote:

> f = 8270.1000 Hz
> Start time: 07.November.2017  16:00:00 UTC
> Symbol period: 60 s
> Characters: 3
> CRC bits: 9
> Coding 16K21A
> Duration: 12:32

> Paul, did you copy my message from last night and the night
> before?

Yes, a strong signal here and perfect decode of the 3 chars:

            H-field           E-field             E+H field
 7th/8th  10.5 dB 99.8 deg   9.0 dB 107.3 deg   12.5 dB 103.3 deg
 8th/9th  14.1 dB 88.3 deg  12.5 dB  93.8 deg   17.3 dB  90.9 deg

> I am getting no decode at RC4HAA, even when stacking both nights.

Signal phase repeated fine both nights.  Given the S/N of your 2 char
success, you would be very lucky to do 3 chars in one night, but two
nights ought to do it.

--
Paul Nicholson
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