Return-Path: Received: from mtain-dc09.r1000.mx.aol.com (mtain-dc09.r1000.mx.aol.com [172.29.64.137]) by air-dc10.mail.aol.com (v129.4) with ESMTP id MAILINDC101-86064c2d98e42fb; Fri, 02 Jul 2010 03:44:36 -0400 Received: from post.thorcom.com (post.thorcom.com [193.82.116.20]) by mtain-dc09.r1000.mx.aol.com (Internet Inbound) with ESMTP id 23981380000A0; Fri, 2 Jul 2010 03:44:35 -0400 (EDT) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1OUauT-00030O-Va for rs_out_1@blacksheep.org; Fri, 02 Jul 2010 08:43:41 +0100 Received: from [193.82.116.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1OUauT-00030F-FV for rsgb_lf_group@blacksheep.org; Fri, 02 Jul 2010 08:43:41 +0100 Received: from out1.ip07ir2.opaltelecom.net ([62.24.128.243]) by relay1.thorcom.net with esmtp (Exim 4.63) (envelope-from ) id 1OUauS-0002Hp-Qd for rsgb_lf_group@blacksheep.org; Fri, 02 Jul 2010 08:43:41 +0100 X-IronPort-Anti-Spam-Filtered: true X-IronPort-Anti-Spam-Result: Av0EANo1LUxZ8V4E/2dsb2JhbACBQp4ocb1ZhSUEimU X-IronPort-AV: E=Sophos;i="4.53,525,1272841200"; d="scan'208,217";a="452053327" Received: from unknown (HELO laptopcore2) ([89.241.94.4]) by out1.ip07ir2.opaltelecom.net with ESMTP; 02 Jul 2010 08:43:33 +0100 From: "g3zjo" To: Date: Fri, 2 Jul 2010 08:43:32 +0100 Message-ID: <000001cb19ba$465f6720$0202a8c0@laptopcore2> MIME-Version: 1.0 X-Priority: 3 (Normal) X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook, Build 10.0.2616 Importance: Normal In-Reply-To: X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2900.2670 X-Spam-Score: 0.0 (/) X-Spam-Report: autolearn=disabled,HTML_MESSAGE=0.001 Subject: RE: LF: 137.500 kHz ROS MF-1 beacon Content-Type: multipart/alternative; boundary="----=_NextPart_000_0001_01CB19C2.A823CF20" X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: X-Spam-Status: No, hits=0.3 required=5.0 tests=HTML_50_60, HTML_FONTCOLOR_UNKNOWN,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-sid: 3039ac1d40894c2d98e3254c X-AOL-IP: 193.82.116.20 X-AOL-SPF: domain : blacksheep.org SPF : none ------=_NextPart_000_0001_01CB19C2.A823CF20 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Hi Andy >Is the S/N calculation being a bit optimistic? The calculation in WSJT / WSPR gives an artificially high S/N value if the input bandwidth is restricted below >a complete 2.5kHz's worth, and if impulsive noise is present. So could ROS be suffering some similar effect? I think the reports should be taken as 'As Indicated By' - WSPR or ROS. I have no idea how the S/N figure is produced but by observation in both systems it is obvious that averaging goes on. Last night some of my S/N figures from ROS of -31dB were from a frame which had QSB -25dB short peaks and -35db troughs. I have a WSPR capture from 6m in which my signal is decoded 51Hz lower than the signal frequency, due to Aircraft Doppler. The reflection is logically and visibly much weaker than the direct path signal. Yet WSPR has reported it only 1dB lower. The report is enhanced by another reflection from another Aircraft which is much stronger and does not de-code due to a 15Hz plus varying Doppler shift, it sweeps down in frequency and joins the decoded reflection for less than on third of the data period. These are real life happenings, quite different from laboratory figures. If the AS description sounds like Chinese, I can see the critics saying 51Hzis due to mains hum already, it isn't. I can point you to the screen grabs and tests we were doing. Eddie G3ZJO ------=_NextPart_000_0001_01CB19C2.A823CF20 Content-Type: text/html; charset="us-ascii" Content-Transfer-Encoding: quoted-printable

Hi Andy

 

>Is the S/N calculation being a bit optimi= stic?  The calculation in WSJT / WSPR gives an artificially high S/N value if the= input bandwidth is restricted below >a complete 2.5kHz's worth, and if im= pulsive noise is present.  So could ROS be suffering some similar effect?=

 

I think the rep= orts should be taken as ‘As Indicated By’ - WSPR or ROS. I have no idea how the S/N figure= is produced but by observation in both systems it is obvious that averagi= ng goes on.

Last night some= of my S/N figures from ROS of -31dB were from a frame which had QSB -25dB short peaks and -35db= troughs.

 

I have a WSPR= capture from 6m in which my signal is decoded 51Hz lower than the signal frequency, due to Aircraf= t Doppler. The reflection is logically and visibly much weaker than the= direct path signal. Yet WSPR has reported it only 1dB lower. The report is en= hanced by another reflection from another Aircraft which is much stronger and do= es not de-code due to a 15Hz plus varying Doppler shift, it sweeps down in frequency= and joins the decoded reflection for less than on third of the data period.

 

These are real= life happenings, quite different from laboratory figures.

 

If the AS descr= iption sounds like Chinese, I can see the critics saying 51Hzis due to mains hum already, it isn&#= 8217;t. I can point you to the screen grabs and tests we were doing.

 

Eddie G3Z= JO

 

 

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