Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by mtain-mp06.r1000.mx.aol.com (Internet Inbound) with ESMTP id 6D8B938000098; Sat, 24 Sep 2011 15:14:02 -0400 (EDT) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1R7Xei-0001mL-Ey for rs_out_1@blacksheep.org; Sat, 24 Sep 2011 20:12:56 +0100 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1R7Xeg-0001mC-PN for rsgb_lf_group@blacksheep.org; Sat, 24 Sep 2011 20:12:54 +0100 Received: from mail-vx0-f171.google.com ([209.85.220.171]) by relay1.thorcom.net with esmtp (Exim 4.63) (envelope-from ) id 1R7Xee-0007i6-JX for rsgb_lf_group@blacksheep.org; Sat, 24 Sep 2011 20:12:54 +0100 Received: by vcbfk12 with SMTP id fk12so3496172vcb.16 for ; Sat, 24 Sep 2011 12:12:46 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=gamma; h=mime-version:sender:in-reply-to:references:date :x-google-sender-auth:message-id:subject:from:to:content-type; bh=dvIFPgHJjwKa7kb41z+tqe02km2KWQUT5ADaic6MkDo=; b=hmiBXakxxSFM5nYhVKMMgiChz210yAeAs1BztdN3lHaKgZzx4egp8ScnSn2VLZsw7i mt2hHm2KixMbD8/OJl+T4xaCyVXypEe0kuykfuiCaeuyiXB09lQCWWklPs1UtQKPYQdB pO1nzhc7ZkTyZ8jimruAdUxcicb4prhcFcs3c= MIME-Version: 1.0 Received: by 10.52.177.7 with SMTP id cm7mr4588141vdc.37.1316891566281; Sat, 24 Sep 2011 12:12:46 -0700 (PDT) Received: by 10.220.194.195 with HTTP; Sat, 24 Sep 2011 12:12:46 -0700 (PDT) In-Reply-To: <976E96347FDF49FEB91588B891BF47AF@White> References: <976E96347FDF49FEB91588B891BF47AF@White> Date: Sat, 24 Sep 2011 20:12:46 +0100 X-Google-Sender-Auth: Qawdt4EmCz6hU7HALDK8v2RSay8 Message-ID: From: Gary - G4WGT To: rsgb_lf_group@blacksheep.org X-Spam-Score: 0.0 (/) X-Spam-Report: autolearn=disabled,HTML_MESSAGE=0.001 Subject: Re: LF: DF6NM 23-09-2011 Content-Type: multipart/alternative; boundary=20cf3071ccc404134804adb4b606 X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: X-Spam-Status: No, hits=0.5 required=5.0 tests=HTML_40_50,HTML_MESSAGE autolearn=no version=2.63 X-SA-Exim-Scanned: Yes Sender: owner-rsgb_lf_group@blacksheep.org Precedence: bulk Reply-To: rsgb_lf_group@blacksheep.org X-Listname: rsgb_lf_group X-SA-Exim-Rcpt-To: rs_out_1@blacksheep.org X-SA-Exim-Scanned: No; SAEximRunCond expanded to false x-aol-global-disposition: G X-AOL-SCOLL-SCORE: 0:2:503774496:93952408 X-AOL-SCOLL-URL_COUNT: 0 X-AOL-SCOLL-AUTHENTICATION: mail_rly_antispam_dkim-m242.1 ; domain : gmail.com DKIM : fail x-aol-sid: 3039ac1dc14a4e7e2bf9589c X-AOL-IP: 195.171.43.25 X-AOL-SPF: domain : blacksheep.org SPF : none --20cf3071ccc404134804adb4b606 Content-Type: text/plain; charset=ISO-8859-1 Hi Marcus, LF, Pleased it provided useful feedback. I am hoping to optimise the system, both from the receiver stability & SpecLab. The receiver is quite good but does show temperature stability issues at these narrow systems. I am considering trying a similar sound card receiver to the one Stefan DK7FC has recently posted in his mails. I am not at all sure about sound card sampling correction at this frequency range, I have no problem at the 8.970kHz range with using the MSK transmissions at VLF but with the narrow bandwidth of the system at 137kHz it presents a different situation for me. Thank you for your suggestions, I will try them in due course. 73, Gary - G4WGT. On 24 September 2011 17:55, Markus Vester wrote: > ** > Hi Gary, > > this is excellent, and much appreciated! I had basically tried to provide a > readable signature on Chris' grabbers, but in the end QRSS 1200 turned out > to be a bit fast for those. I guess the general concept is more suitable for > straight unmodulated carriers... > > Your screenshot reveals my transmit instability near the end of the "N", > when my (DHO-based) samplerate locking temporarily failed, and the > audio frequency jumped by 20 mHz. Do you have plans for further > optimization? The Loran line visible on 137780.419 (Anthorn et al) may come > in handy to evaluate sensitivity and stability during development. > > One thing I would perhaps suggest is to activate the "one pixel per FFT > bin" option in Speclab. If you don't, and zoom in instead, the brightness of > each pixel is driven by the highest power from a number of adjacent FFT > bins, which in effect increases the visible noise level significantly. Of > course the downside is that the visible range becomes quite narrow, > requiring TX stations to cuddle closely around a prescribed QRG to be seen > on the grabber slot. On the other hand, you can still move the slot around a > posteriori, and manually search for possible missed activity. > > Best 73, and thanks > > Markus (DF6NM) > > > *From:* Gary - G4WGT > *Sent:* Saturday, September 24, 2011 12:26 PM > *To:* LF Group (RSGB) > *Subject:* LF: DF6NM 23-09-2011 > > Hi Marcus, LF, > > Please forgive the frequency accuracy & stability on my experimental very > slow (2 mHz) SpecLab screen but the signal is clearly visible. > > Receiver - JRC NRD-345 > Antenna - PA0RDT Mini-Whip at 9 metres > > 73 > > Gary - G4WGT > > --20cf3071ccc404134804adb4b606 Content-Type: text/html; charset=ISO-8859-1 Content-Transfer-Encoding: quoted-printable Hi Marcus, LF,

Pleased it provided useful feedback.

I am hoping to optimise the system, both from the rece= iver stability & SpecLab. The receiver is quite good but does show temp= erature stability issues at these narrow systems. I am considering trying a= similar sound card receiver to the one Stefan DK7FC has recently posted in= his mails.

I am not at all sure about sound card sampling correcti= on at this frequency range, I have no problem at the 8.970kHz range with us= ing the MSK transmissions at VLF but with the narrow bandwidth of the syste= m at 137kHz it presents a different situation for me.

Thank you for your suggestions, I will try them in due = course.

73, Gary - G4WGT.


On 24 September 2011 17:55, Markus Vester <markusvester@aol.com&= gt; wrote:
Hi Gary,
=A0
this is excellent, and much appreciate= d!=A0I had=20 basically=A0tried to provide a readable signature on Chris' grabbers, b= ut in=20 the end QRSS 1200=A0turned out to be=A0a bit fast for those.=A0I guess=20 the general concept=A0is=A0more suitable for straight unmodulated=20 carriers...
=A0
Your screenshot=A0reveals my=A0transmi= t=20 instability near the end of the "N", when=A0my (DHO-based) sample= rate locking=20 temporarily=A0failed, and the audio=A0frequency jumped=A0by 20 mHz.=20 Do you have plans for further optimi= zation? The=20 Loran line visible on 137780.419=A0(Anthorn et al) may come in handy to=20 evaluate sensitivity and stability during=A0development.
=A0
One thing I would perhaps suggest=A0is= to=20 activate the "one pixel per FFT bin" option in Speclab. If you do= n't, and=20 zoom=A0in instead, the brightness of each pixel is driven by the=A0highest= =20 power from=A0a number of adjacent FFT bins, which in effect increases the= =20 visible noise level=A0significantly. Of course=20 the downside is that the visible range becomes quite narrow, requiring=A0TX= =20 stations to=A0cuddle closely around a prescribed QRG to be seen on the=20 grabber slot.=A0On the other hand, you can still move the slot around a=20 posteriori, and manually search for possible missed activity.
=A0
Best 73, and thanks
=A0
Markus (DF6NM)
=A0

Sent: Saturday, September 24, 2011 12:26 PM
Subject: LF: DF6NM 23-09-2011

Hi Marcus, LF,=20

Please forgive the frequency accuracy & stability on my experiment= al=20 very slow (2 mHz) SpecLab screen but the signal is clearly visible.

Receiver - JRC NRD-345
Antenna - PA0RDT Mini-Whip at 9 metres

73

Gary - G4WGT


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