Return-Path: Received: (qmail 31338 invoked from network); 25 Apr 2003 15:17:25 -0000 Received: from murphys.services.quay.plus.net (212.159.14.225) by mailstore with SMTP; 25 Apr 2003 15:17:25 -0000 Received: (qmail 20194 invoked from network); 25 Apr 2003 15:17:11 -0000 X-MSMail-Priority: High Received: from post.thorcom.com (193.82.116.70) by murphys.services.quay.plus.net with SMTP; 25 Apr 2003 15:17:11 -0000 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1106 X-SQ: A Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1994wS-0005jo-0w for rsgb_lf_group-outgoing@blacksheep.org; Fri, 25 Apr 2003 16:16:48 +0100 Received: from [212.1.130.141] (helo=smtp-1.visp.telinco.net) by post.thorcom.com with esmtp (Exim 4.14) id 1994wM-0005jf-DW for rsgb_lf_group@blacksheep.org; Fri, 25 Apr 2003 16:16:42 +0100 Received: from [80.40.93.173] (helo=standalone) by smtp-1.visp.telinco.net with smtp (Exim 3.36 #1) id 1994wL-0003SM-00 for rsgb_lf_group@blacksheep.org; Fri, 25 Apr 2003 16:16:41 +0100 Received: by localhost with Microsoft MAPI; Fri, 25 Apr 2003 16:16:00 +0100 Message-ID: <01C30B45.F606B6F0.g4jnt@thersgb.net> From: "Andy talbot" To: rsgb_lf_group@blacksheep.org Date: Fri, 25 Apr 2003 16:14:06 +0100 Importance: high X-Priority: 1 X-Mailer: Microsoft Internet E-mail/MAPI - 8.0.0.4211 MIME-Version: 1.0 Subject: LF: RE: something for the weekend ?? Content-Type: text/plain; charset=us-ascii; format=flowed Content-Transfer-Encoding: 8bit X-Spam-Status: No, hits=2.0 required=5.0tests=X_PRIORITY_HIGHversion=2.53 X-Spam-Level: ** 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 Yes that is correct according to the sheet of trig identities on the wall above my desk. But as I wrote it, the top mixer input is not SIN(A) and COS(B), as the LO signal does not have the 90 degree shift in it. The inputs to the top mixer are ....... COS(A).SIN(B) = SIN((A+B) - SIN(A-B) which is much the same as you give, but with A and B reversed and using the knowledge that SIN(A-B) = -SIN(B-A) Andy -----Original Message----- From: Alan Melia [SMTP:Alan.Melia@btinternet.com] Sent: 2003/04/25 15:29 To: LF-Group Subject: LF: something for the weekend ?? Hi Andy, I am afraid my Terman "Radio Engineers Handbook" 1943 Page 19 gives Sin(A).Cos(B)= Sin(A-B)+Sin(A+B) ....if we forget about the 0.5 factor. but it agrees on the others. This gives you Cos(A-B) + Cos(A+B) out of the top after the 90deg. phase shift and Cos(A-B) - Cos(A+B) out of the bottom ....again cancelling one sideband. I was toying with the idea that Sin(A+pi/2)=Cos(A) but Cos(A+pi/2)= -Sin(A) but that seems irrelevant. Cheers de Alan G3NYK alan.melia@btinternet.com