Re: LF: EA5DOM EbNaut Tx test in 137.485

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

Hello Luis and all,

returned home today and now it's time to 'play' a little bit with our fantastic 'hobby' !

I have tried to search for your signal in the recordings.

This is very easy to do with linux and vlfrx-tools. In fact i'm recording the audio from the LF receiver with the program 'vtwrite'. This program creates its proper files in a dedicated hard disk (used only for the storage) . I setted vtwrite to create one file each 24 hour.  It is very confortable to retry the raw data by using 'vtread' program, just specify the date, the duration and the location of the storage directory. In this way, it is possible to post-processings any possible transmissions in the audio band recordered. You can 'play' anytime the raw file and change the parameters, offsets or NB settings.

Nice tools, thanks again to Paul Nicholson.

But, sorry to say that,  till now,  the search of your 'DOM' message is without results.

Maybe one of the parameters you have announced is different from that you have really used. That's becouse the duration for

16K21A, CRC=19, 3 Chars, 2 (total 912 bits) is more than 30 minutes for T=2s and maybe some symbols were not transmitted due to your 'half hour beaconing'.

There is also a lack of sensitivity on LF on my receiver. Noise floor, also during nightime, is very high (one week ago was less)  and i suspect some hardware trouble here (groundings or a new local 'macoomba' noise). Investigation is started.

I have  a second receiver, GPS referenced,   tuned on MF op8 band (478.450-478.550)   https://www.qsl.net/iz7slz/OPDS8/opds8.jpg

Interesting to see and analyze some OP8 signals on that band. The opds program (from Markus DF6NM) is giving some interesting results ( https://www.qsl.net/iz7slz/OPDS8/DETECTED8.TXT )

Dear Luis, can i suggest you (or other operators) to try an EbNaut transmission on that MF band ?

Autodecoder webpage is setted for R3RWR transmissions now, but it's easy to change parameters. You can transmitt anytime, since also MF band is recordered in a separate storage media.

Waiting for your comment.

73, Domenico IZ7SLZ

On Fri, 21 Sep 2018 at 10:27, VIGILANT Luis Fernández <luis@vigilant.es> wrote:

Hi EbNaut

 

Yesterday installed the PA and my intention was to transmit with the lowest possible power (about 24W at 12V in LOW mode)

but Murphy confirmed that the lowest possible power …..is always zero. Something went wrong L

 

Anyway cound trim the antenna to resonance. It was a couple of KHz down. And using the mosfet driver at 14V

could see some improvements in output level and the device clearly heating. No Vrms meter available so I can’t

confirm the output power or current for this transmissions

 

Trying to check if there could be a decode at Domenico’s EbNaut decoder I transmitted all night

with the usual parameters for weak signal in a less than half an hour message. May be Stefan can

use the files he is recording and check for the transmission

 

f = 137485.000 Hz
Start time: 20.SEP.2018  19:00:00 UTC up to 05:30:00 UTC (message starting at minute 00 and 30 every hour)
Symbol period: 2s
Characters: 3
CRC bits: 19
Coding 16K21A

The message is “DOM”, so if anyone wants to correlate the received signal and get some extra dBs. This is extremely

weak signal. The input power to the antenna must be well under 1W, so the ERP must be very low

 

There was no decode at Domenico’s grabber

https://www.qsl.net/iz7slz/EBNAUT/DECODED.TXT

 

Just for measurement of signal I can run a permanent carrier tonight if this can help

 

73 de Luis

EA5DOM