Return-Path: Received: (qmail 26845 invoked from network); 7 Oct 1999 10:52:49 +0100 Received: from unknown (HELO magnus.force9.net) (195.166.128.27) by guiness.force9.net with SMTP; 7 Oct 1999 10:52:49 +0100 Received: (qmail 11188 invoked from network); 7 Oct 1999 09:52:22 -0000 Received: from unknown (HELO post.thorcom.com) (212.172.148.70) by magnus.plus.net.uk with SMTP; 7 Oct 1999 09:52:22 -0000 Received: from majordom by post.thorcom.com with local (Exim 3.02 #1) id 11Z9Xc-0002jQ-00 for rsgb_lf_group-outgoing@blacksheep.org; Thu, 07 Oct 1999 10:08:48 +0100 Received: from [143.179.236.31] (helo=Iguanodon.big-orange.net) by post.thorcom.com with esmtp (Exim 3.02 #1) id 11Z9Xa-0002jL-00 for rsgb_lf_group@blacksheep.org; Thu, 07 Oct 1999 10:08:47 +0100 Received: from w8k3f0 ([143.179.150.226]) by Iguanodon.big-orange.net (Netscape Messaging Server 3.6) with SMTP id AAA3F34 for ; Thu, 7 Oct 1999 11:08:41 +0200 Message-ID: <000601bf10a4$c3dec220$e296b38f@w8k3f0> From: "Dick Rollema" To: rsgb_lf_group@blacksheep.org Subject: LF: Re: DGPS reception using the phasing method Date: Thu, 7 Oct 1999 11:16:40 +0200 MIME-Version: 1.0 Content-Type: text/plain; charset=iso-8859-1; format=flowed Content-Transfer-Encoding: 8bit X-Priority: 3 X-MSMail-Priority: Normal X-Mailer: Microsoft Outlook Express 4.72.3110.5 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1106 Precedence: bulk Reply-To: rsgb_lf_group@blacksheep.org X-Listname: rsgb_lf_group Sender: Johan, Harry, PA0LQ, has a computer programma by which he can design a network like you want, using opamps and he is willing to do that for you. I suggest you sent Harry a letter, confirming the specs in your e-mail and your address. If you want better accuracy than 1 degree (40 dB sideband suppression) Harry can accommodate that as well, but it means more stages in the network of course. Harry's address is: H.A.A. Grimbergen, PA0LQ Lijtweg 1202 2341 HE Oegstgeest The Netherlands Harry has no e-mail or fax facility. 73, Dick, PA0SE JO22GD D.W. Rollema V.d. Marckstraat 5 2352 RA Leiderdorp The Netherlands Tel. +31 71 589 27 34 E-mail: d.w.rollema@gironet.nl -----Oorspronkelijk bericht----- Van: Johan Bodin Aan: homebrew@qth.net ; lowfer@qth.net ; rsgb_lf_group@blacksheep.org Datum: donderdag 7 oktober 1999 0:58 Onderwerp: LF: DGPS reception using the phasing method Hi dear Homebrewers & Lowfers! I got a Garmin GPS 12 receiver on my birthday which immediately resulted in wild plans to build a DGPS beacon receiver ;-) I want to try a phasing SSB receiver with about 500 Hz output. The reason for using 500 Hz IF is that there is free PIC software available for synchronizing onto a "hard-limited" MSK signal at 500 Hz and converting it into a RTCM-104 data stream that can be sent to a GPS receiver. The rejection of unwanted sideband is not as important as in the case of serious HF work since the DGPS beacon of interest is always the nearest (and strongest) one. Since the next-to-strongest beacon cannot be stronger than the strongest one (;-), I guess that 20 dB rejection (or so..) would be sufficient. The audio phase shift networks I have seen so far (in the R2 receiver etc.) are designed to give a 90 degree phase shift over the entire speech band which is a frequency decade! The bandwidth of the MSK beacon signals is just a few hundred Hz (100 or 200 baud). I guess the phase shifter can be made quite simple (I want to make the receiver as small as possible). Well... to the point... I am searching for a simple circuit that is able to phase shift two signals, in the range 300 to 700 Hz, by 90 degrees (+/- 1 degree or so) with respect to each other, without introducing any large amplitude differencies between the two channels. The phase, and amplitude, response outside the above mentioned frequency range is irrelevant, a good bandpass filter will follow after "the I/Q summing point" anyway. Any ideas? 73 de Johan Bodin, SM6LKM