Return-Path: X-Spam-DCC: paranoid 1170; Body=2 Fuz1=2 Fuz2=2 X-Spam-Checker-Version: SpamAssassin 3.1.3 (2006-06-01) on lipkowski.org X-Spam-Level: X-Spam-Status: No, score=-1.0 required=5.0 tests=BAYES_00,DNS_FROM_AHBL_RHSBL, HTML_10_20,HTML_MESSAGE,SPF_PASS autolearn=no version=3.1.3 Received: from post.thorcom.com (post.thorcom.com [195.171.43.25]) by paranoid.lipkowski.org (8.13.7/8.13.7) with ESMTP id u8SMGqYT006018 for ; Thu, 29 Sep 2016 00:16:53 +0200 Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1bpN6F-0001Lq-64 for rs_out_1@blacksheep.org; Wed, 28 Sep 2016 23:13:11 +0100 Received: from [195.171.43.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1bpN6E-0001Lh-G6 for rsgb_lf_group@blacksheep.org; Wed, 28 Sep 2016 23:13:10 +0100 Received: from smtp08.smtpout.orange.fr ([80.12.242.130] helo=smtp.smtpout.orange.fr) by relay1.thorcom.net with esmtps (TLSv1:DHE-RSA-AES256-SHA:256) (Exim 4.87) (envelope-from ) id 1bpN6C-0003Xu-8e for rsgb_lf_group@blacksheep.org; Wed, 28 Sep 2016 23:13:09 +0100 Received: from [10.41.185.229] ([10.162.66.188]) by mwinf5d68 with ME id pAD21t00R43icX603AD33R; Thu, 29 Sep 2016 00:13:04 +0200 X-ME-Helo: [10.41.185.229] X-ME-Date: Thu, 29 Sep 2016 00:13:04 +0200 X-ME-IP: 10.162.66.188 Date: Thu, 29 Sep 2016 00:12:59 +0200 From: Michel Brunel X-Priority: 3 (Normal) Message-ID: <924779203.20160929001259@mterrier.net> To: rsgb_lf_group@blacksheep.org In-Reply-To: <15772acd0cf-3311-273e@webprd-m58.mail.aol.com> References: <1544518546.20160928191058@mterrier.net> <15772acd0cf-3311-273e@webprd-m58.mail.aol.com> MIME-Version: 1.0 X-Scan-Signature: 13ce2d45c6831942db3d21680606cc2e Subject: Re: LF: F5WK EbNaut Content-Type: multipart/alternative; boundary="----------01018E078366A3054" 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-Scanned-By: MIMEDefang 2.56 on 10.1.3.11 Status: O X-Status: X-Keywords: X-UID: 8871 ------------01018E078366A3054 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: quoted-printable Hi Markus, Yes I'm still transmitting with the same ERP as the other days. The antenna is brought to resonance by a series loading coil and impedance = matching is performed by a tapped transformer. It seems to me that overcurrent applies only with an inductive mismatch, ot= herwise it tends toward zero. This overcurrent is not noticeable at all, ex= cept that it triggers the ACS712 Hall effect sensor and the PIC A/D routine= ! =20 Anyway the best approach is to use a DDS. I already tried that, but as my c= lass D PA requires 2*F, the phase offset should be 2*180=C2=B0 and as 360= =C2=B0 means 0=C2=B0, I thought that a immediate lower value - ie 174,375= =C2=B0 for the AD9851 - was not adequate. All the best, Michel - f5wk Le mercredi 28 septembre 2016 =C3=A0 23:21:50, Markus =C3=A9crivait : Hi Michel, your signal is not weak at all, surely good enough for comfortable QRSS3 re= ading here.=20 Regarding overcurrent trip: I found that for safest operation of a class-D = PA, the antenna impedance should be presented as a series resonant circuit = to the transistors, because that will have high impedance for any out-of-re= sonance spectral components. Then during phase reversals, the current will = experience a dip rather than a peak. The impedance condition depends on the= total phase shift of the matching circuits and low pass filters, which sho= uld ideally be 0 or 180=C2=B0. However feeding into a 50-ohm loading coil t= ap (or through certain PI- or T-filters) tends to have around 90=C2=B0, tra= nsforming series resonance into parallel resonance, and presenting a short-= circuit to the PA for out-of-band exciation. Tonight there seems to be a (somewhat weaker) trace on your QRG again, are = you still sending EbNaut? Best 73, Markus (DF6NM) -----Urspr=C3=BCngliche Mitteilung-----=20 Von: Michel Brunel An: Domenico IZ7SLZ Verschickt: Mi, 28 Sept 2016 7:13 pm Betreff: Re: LF: F5WK EbNaut Hi, Big thanks to Domenico, Markus and Stefan for their successful decoding of = my EbNaut transmissions. Ebnaut decoding is not an easy task especially with weak signal. I fear my GPSDO frequency was not as accurate than expected. I had the bad = idea to use a low cost GPS antenna wich performed not as good as the professional grade antenna I used for tests at home. Thu= s some jitter and phase jumps depending on GPS constellation position. As a "proof of concept" I made Loran-C records during the day using the eb= naut setup and results are sometime good sometime not so good. The transmitter overcurrent was randomly triggered by the phase reversal. = Bpsk modulation is performed synchronously by exclusive OR gates, between t= he D flip-flop and the MOS drivers. Phase reversal is like changing the fre= quency for a very short time, which leads to a current pike due to the high= Q of the LF antenna. Decision was taken to bypass the overcurrent detectio= n. The good way to do bpsk modulation is with a suitable DDS such as AD9852.= =20 I found the antenna performs poorly at LF since the radials are burried in = a sandy soil, as time goes on. No big deal for ebnaut though. A lot of things to improve for my next LF campaign,=20 73, Michel - f5wk/P=20 -- ------------01018E078366A3054 Content-Type: text/html; charset=utf-8 Content-Transfer-Encoding: quoted-printable Re: LF: F5WK EbNaut Hi Markus,

Yes I'm still transmitting with the same ERP as the other days.

The antenna is brought to resonance by a series loading coil and impedance = matching is performed by a tapped transformer.
It seems to me that overcurrent applies only with an inductive mismatch, ot= herwise it tends toward zero. This overcurrent is not noticeable at all, ex= cept that it triggers the ACS712 Hall effect sensor and the PIC A/D routine= !  
Anyway the best approach is to use a DDS. I already tried that, but as my c= lass D PA requires 2*F, the phase offset should be 2*180=C2=B0 and as 360= =C2=B0 means 0=C2=B0, I thought that a immediate lower value - ie 174,375= =C2=B0 for the AD9851 - was not adequate.

All the best,
Michel - f5wk

Le mercredi 28 septembre 2016 =C3=A0 23:21:50, Markus =C3=A9crivait :


 Hi Michel,

your signal is not weak at all, surely good enough for comfortable QRSS3 re= ading here. 

Regarding overcurrent trip: I found that for safest operation of a class-D = PA, the antenna impedance should be presented as a series resonant circuit = to the transistors, because that will have high impedance for any out-of-re= sonance spectral components. Then during phase reversals, the current will = experience a dip rather than a peak. The impedance condition depends on the= total phase shift of the matching circuits and low pass filters, which sho= uld ideally be 0 or 180=C2=B0. However feeding into a 50-ohm loading coil t= ap (or through certain PI- or T-filters) tends to have around 90=C2=B0, tra= nsforming series resonance into parallel resonance, and presenting a short-= circuit to the PA for out-of-band exciation.

Tonight there seems to be a (somewhat weaker) trace on your QRG again, are = you still sending EbNaut?

Best 73,
Markus (DF6NM)



-----Urspr=C3=BCngliche Mitteilung----- 
Von: Michel Brunel <f5wk@mterrier.net>
An: Domenico IZ7SLZ <rsgb_lf_group@blacksheep.org>
Verschickt: Mi, 28 Sept 2016 7:13 pm
Betreff: Re: LF: F5WK EbNaut

Hi,

Big thanks to Domenico, Markus and Stefan for their successful decoding of = my EbNaut transmissions.
Ebnaut decoding is not an easy task especially with weak signal.

I fear my GPSDO frequency was not as accurate than expected. I had the bad = idea to use a low cost GPS antenna wich performed
not as good as the professional grade antenna I used for tests at home. Thu= s some jitter and phase jumps depending on GPS constellation position.
As a "proof of concept" I made Loran-C records during the day  using t= he ebnaut setup and results are sometime  good sometime not so good.
The transmitter overcurrent was randomly  triggered by the phase rever= sal. Bpsk modulation is performed synchronously by exclusive OR gates, betw= een the D flip-flop and the MOS drivers. Phase reversal is like changing th= e frequency for a very short time, which leads to a current pike due to the= high Q of the LF antenna. Decision was taken to bypass the overcurrent det= ection.
The good way to do bpsk modulation is with a suitable DDS such as AD9852.&n= bsp;

I found the antenna performs poorly at LF since the radials are burried in = a sandy soil, as time goes on. No big deal for ebnaut though.

A lot of things to improve for my next LF campaign, 

73,
Michel - f5wk/P 






--  ------------01018E078366A3054--