Return-Path: Received: (qmail 6621 invoked from network); 10 May 2000 14:18:14 -0000 Received: from unknown (HELO post.thorcom.com) (212.172.148.70) by grants.core.plus.net.uk with SMTP; 10 May 2000 14:18:14 -0000 Received: from majordom by post.thorcom.com with local (Exim 3.02 #1) id 12pXAm-0002Kq-00 for rsgb_lf_group-outgoing@blacksheep.org; Wed, 10 May 2000 15:09:12 +0100 Content-Transfer-Encoding: 8bit Received: from bob.dera.gov.uk ([192.5.29.90]) by post.thorcom.com with esmtp (Exim 3.02 #1) id 12pXAh-0002Kk-00 for rsgb_lf_group@blacksheep.org; Wed, 10 May 2000 15:09:07 +0100 Received: by bob.dera.gov.uk; (8.8.8/1.3/10May95) id PAA09473; Wed, 10 May 2000 15:12:08 +0100 (BST) X-Priority: 3 X-MSMail-Priority: Normal Received: (qmail 31077 invoked from network); 10 May 2000 15:04:51 -0000 Received: from gauntlet.mail.dera.gov.uk (172.16.9.10) by baton.dera.gov.uk with SMTP; 10 May 2000 15:04:51 -0000 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1106 Received: by gauntlet.mail.dera.gov.uk; id NAA28449; Wed, 10 May 2000 13:53:15 GMT Received: from unknown(146.80.11.40) by gauntlet.mail.dera.gov.uk via smap (3.2) id xma028430; Wed, 10 May 00 13:52:55 GMT Received: from frn-gold-1.dera.gov.uk (unverified) by mailguard.dera.gov.uk (Content Technologies SMTPRS 4.1.5) with ESMTP id for ; Wed, 10 May 2000 15:13:14 +0100 Received: by FRN-GOLD-1 with Internet Mail Service (5.0.1460.8) id <2J00BL95>; Wed, 10 May 2000 15:07:25 +0100 Message-ID: <3617AC3245C2D1118A840000F805359C017528CD@pdw-mercury-1.dera.gov.uk> From: "Talbot Andrew" To: rsgb_lf_group@blacksheep.org Subject: RE: LF: DFCW Parameters Date: Wed, 10 May 2000 15:07:24 +0100 MIME-Version: 1.0 X-Mailer: Internet Mail Service (5.0.1460.8) Content-Type: text/plain; charset=iso-8859-1; format=flowed Precedence: bulk Reply-To: rsgb_lf_group@blacksheep.org X-Listname: rsgb_lf_group Sender: >Theoreticaly you can gain 5.2dB by going from 3 to 10 sec. dot length. >sample rate. > Rik Only if the resolution of the waterfall analysis software is 3 times less. Does Spectran use the same windowing function as Spectrogram ? Depending on which window is used, the effective bandwidth of a spectrum display can be from one to three FFT bins, trading off display sidelobes against effective bandwidth. ......... I installed a 1Hz bandwidth filter in the RA1792 over the weekend, by mixing the 455kHz second IF down to 32765 Hz, followed by a ladder filter made from 5 watch crystals, then mixing back up to 455kHz with the same local oscillator so it's own instability cancels out. This LO needs to be tuneable to interpolate over the 10 Hz step size of the Rx. Results are interesting to say the least ! AGC action is completely destroyed as the 1Hz filter has a group delay of over a second and so the AGC loop goes wildly unstable - hence manual gain control is essential. All signals sound like a perfect audio tone - even static crashes sound like a carrier with slow fading on it ! Loran lines are tones in this BW. But it really does bring signals out of the noise, even in the severe thunder storms of the last few days. Andy G4JNT -- The Information contained in this E-Mail and any subsequent correspondence is private and is intended solely for the intended recipient(s). For those other than the recipient any disclosure, copying, distribution, or any action taken or omitted to be taken in reliance on such information is prohibited and may be unlawful.