Return-Path: Received: (qmail 20126 invoked from network); 26 Apr 2003 08:33:31 -0000 Received: from warrior.services.quay.plus.net (212.159.14.227) by mailstore with SMTP; 26 Apr 2003 08:33:31 -0000 X-Priority: 3 X-MSMail-Priority: Normal Received: (qmail 18871 invoked from network); 26 Apr 2003 08:33:34 -0000 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1106 Received: from post.thorcom.com (193.82.116.70) by warrior.services.quay.plus.net with SMTP; 26 Apr 2003 08:33:34 -0000 X-SQ: A Received: from majordom by post.thorcom.com with local (Exim 4.14) id 199L76-0001kw-Ew for rsgb_lf_group-outgoing@blacksheep.org; Sat, 26 Apr 2003 09:32:52 +0100 Received: from [205.188.157.41] (helo=imo-d09.mx.aol.com) by post.thorcom.com with esmtp (Exim 4.14) id 199L71-0001kn-JY for rsgb_lf_group@blacksheep.org; Sat, 26 Apr 2003 09:32:47 +0100 Received: from DL4YHF@aol.com by imo-d09.mx.aol.com (mail_out_v34.22.) id l.18d.192bf272 (3988) for ; Sat, 26 Apr 2003 04:32:13 -0400 (EDT) From: DL4YHF@aol.com Message-ID: <18d.192bf272.2bdb9e0d@aol.com> Date: Sat, 26 Apr 2003 04:32:13 EDT To: rsgb_lf_group@blacksheep.org MIME-Version: 1.0 X-Mailer: 6.0 for Windows XP sub 50 Subject: Re: LF: RE: something for the weekend ?? Content-Type: text/html; charset=windows-1252 X-Spam-Status: No, hits=-1.1 required=5.0tests=HTML_10_20,HTML_MESSAGE,MIME_LONG_LINE_QP,NO_REAL_NAME, QUOTED_EMAIL_TEXTversion=2.53 X-Spam-Checker-Version: SpamAssassin 2.53 (1.174.2.15-2003-03-30-exp) X-SA-Exim-Scanned: Yes Sender: Precedence: bulk Reply-To: rsgb_lf_group@blacksheep.org X-Listname: rsgb_lf_group X-SA-Exim-Rcpt-To: rsgb_lf_group-outgoing@blacksheep.org X-SA-Exim-Scanned: No; SAEximRunCond expanded to false Content-transfer-encoding: 8bit Hi Steward, Andy and group,


I am not sure about the physics of this.

The 90deg phase shifter has to be some sort of dispersion
device (propagation time varies with frequency), and this
will operate on the fourier components of the waveform.

The fourier components present are sin(a+b) and sin(a-b),
not the complex waveform cos(a)*sin(b).

Therefore the phaseshift will apply individually to
sin(a+b) and to sin(a-b).

Can we go back to the physical device itself, and confirm
that the IF phase shifter is shifting by 90deg (as opposed to
say 270deg) and that you can select both sidebands
properly with the add/subtract?

Stewart G3YSX


Thanks for the correction, accepted ! To delay a 'broadband' signal
   cos(a) * sin(b)

by simply substituting it with
   cos(a+90°) * sin(b+90°)
was a mistake by myself; it would be ok if there wasn't that multiply thing in between ;-)

However, Andy's 2nd diagram does work, it is also shown in the ARRL handbook. Think I'll have to find my old math textbook, pre-heat the brain with a good cup o' coffe and make another attempt..

Cheers,
Wolf.