Hello Jan,

me neither, maybe no one was transmitting...or they changed freq...or...or...

73

Steve 

G3XKR

On Wed, Mar 2, 2016 at 7:32 AM, 'Jan Lustrup' [email protected] [rsgb_lf_group] <[email protected]> wrote:

 

Monitored 137.630 all night...no Wolf signals decoded  here  in JO28XJ.

Jan LA3EQ

 

From: [email protected] [mailto:[email protected]]
Sent: 1. mars 2016 23:32
To: [email protected]
Subject: Re: [rsgb_lf_group] WD2XES WOLF

 

 

For DCF77 , read '39....

 

'jnt

 

 

On 1 March 2016 at 22:28, Andy Talbot <[email protected]> wrote:

Do you actually need to remove DCF77 from the passband at all?   If you can turn the AGC off  - if that is possible in the FT817 [*] - then use the manual gain control so it is just short of overloading when the strong station keys.   Just because an interferer sounds loud, doesn't mean its contribution in the processed bandwidth will be all that great.

 

The DSP software optimally filters the signal it it trying to decode, and that isn't necessarily with any shape that looks like a classic bandpass filter. 

 

If you can't turn off AGC, ther eis another possibility.   've just done a quick experiment on my IC746 , leaking in a weak carrier at 137.63kHz to find a tuning point that will work.

 

By going to an SSB tuning point of 135.75kHz, it  places the wanted signal towards the upper end of the passband, generating a tone at 1880Hz and DCF77 has disappeared down the edge of the SSB filter.  Then to run the decoder, just set its tone frequency to 1880.  As mentioned, there are an infinite set of choices.  (Although if you can only tune in 10Hz steps on the receiver, there are only a hundred or so choices)

 

Other pepole use LSB for modes where polarity inversion is permissible.  And this is where PSK score over MFSK modes as it is polarity insensitive.    Just like QRSS and Opera.    You can't do that with WSPR  et-all. (Although it wouldn't be a bad idea if the authors incorporated inverted audio in the latest WSJT-X suite.   Might suggest it)

 

SDRs.,  even basic soundcard based ones, do make life so very much easier

 

Andy  G4JNT

 

[*]   I do have an FT817, but can't be bovvered this time of night wading through its menus and fiddly button sequences to see if that is possible

 

On 1 March 2016 at 22:06, Simon Kennedy [email protected] [rsgb_lf_group] <[email protected]> wrote:

 

Many thanks to everyone who replied to my question. I understand a lot more now!

 

There were some interesting comments from Steve and Andy about filtering (or not) these narrow modes. I am using my 817 which doesn't have any filters but to exclude DCF39 from the passband  I will need to use my Ft920 or maybe my HackRF.

 

73 Simon

G0FCU.

 

On 1 March 2016 at 21:11, 'Roelof Bakker' [email protected] [rsgb_lf_group] <[email protected]> wrote:

 

Hello Steve,

I have never tried to phase to mini-whips, due to lack of real
estate. However, a loop and a mini-whip connected to a MFJ1025 or a
home made phaser gives a nice cardiod reception pattern.

The downside is that at my location a loop receives much more local
noise at VLF/LF/MF which spoils the fun.

I am heavily involved in chasing NDB's and there are other tools
besides antenna directivity to unearth a particular station.

I use Linrad for the real difficult ones and aural copy can be
achieved with an adjacent carrier less than 1 Hz away and mulitiple
carriers within a 10 Hz wide filter.

So after a lot of experiments, I have ended up with just one
antenna!

73,
Roelof, pa0rdt

 

 

 

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