Re: LF: EBNAUT beacon on LF

[Markus Vester <markusvester@aol.com>]

Hi Joe,

thanks again for the files - unfortunately no luck so far. The attached spectrum shows a very strong pilot signal at an offset which drifted slightly from 0.0990 to 0.0897 Hz during the night. But no decode from the 0610 file - perhaps 13 characters was asking a bit too much at the current state of affairs.

The problem with the strong pilot is that it apparently aliases back into the EbNaut channel. Last time we saw a few spurious peaks and a relatively low dB value for "carrier-derived" Eb/N0. I do not know exactly how much the aliasing affects the decodability. It also appears that despite the green status indicator, the frequency offset detector did not really remove the receiver offset anyway. So I would suggest to give up on that for the time being. After reducing the pilot by about 40 dB it will still be visible in the 0.4 mHz FFT bandwidth, enough to serve as an a posteriori frequency marker when processing the files.

I did see mconfig.ini in your directory http://www.ucs.mun.ca/~jcraig/ebnaut but somehow couldn't download it. Could you just tell us the samplerate?

All the best,
Markus (DF6NM)



-----Ursprüngliche Mitteilung-----
Von: jcraig <jcraig@mun.ca>
An: rsgb_lf_group <rsgb_lf_group@blacksheep.org>
Verschickt: So, 18 Dez 2016 9:31 pm
Betreff: Re: LF: EBNAUT beacon on LF

Hi Markus,

The files are uploaded after an infuriating battle with the pc!
A screen grab sl05.jpg is there too.
Strangely, the pilot amplitude had to be increased to get
the green OK rather than yellow warning in the Frq offset
detetor. The ini file was also uploaded. rsNTP was running
during the process.

Good luck and have fun!

Joe

On Sun, 18 Dec 2016, Markus Vester wrote:

> Hi Joe,
>
> that's great news - yes we are surely keen to look for our signals in your recordings.
>
> Dom's and my 29 minute transmissions started on the hour, so the best files would be the ones centered near hh:15. Ric's transmission was somewhat shorter. From your list, I'd probably select the ones ending in xx:10, which are
>
> 12172210.txt,
> 12172310.txt,
> 12180010.txt,
> 12180110.txt,
> 12180210.txt,
> 12180310.txt,
> 12180410.txt,
> 12180510.txt,
> 12180610.txt.
>
> Did you still employ the DDS pilot injection to guide us to the right frequency? Last time the pilot was more than 50 dB above the noise, which may have reduced carrier-EbN0 readout and affected decoding. For future sessions, I'd recommend to reduce the pilot level by about 20 dB.
>
> We'd also need to know the result from your samplerate calibration (1200x.xx Hz). This was displayed during the calibration - if you hadn't noted it at the time you can still read it from the audio correction table or from mconfig.ini.
>
> Was the PC clock steered by NTP or some other means?
>
> Best 73,
>
> Markus
>
>
>
> -----Ursprüngliche Mitteilung-----
> Von: jcraig <jcraig@mun.ca>
> An: rsgb_lf_group <rsgb_lf_group@blacksheep.org>
> Verschickt: So, 18 Dez 2016 2:26 pm
> Betreff: Re: LF: EBNAUT beacon on LF
>
>
> Hi Domenico and Markus,
>
> Here is a list of EbNaut files. I can upload a few of them
> if you would like. Let's hope SR and FO were properly engaged!
> There is a compiled ebnaut on this unix box that I should be using too.
>
> 73
> Joe VO1NA

Spectrum_12180610.png
Description: PNG image