Return-Path: Received: (qmail 27969 invoked from network); 30 Dec 2001 13:08:25 -0000 Received: from unknown (HELO warrior.services.quay.plus.net) (212.159.14.227) by excalibur.plus.net with SMTP; 30 Dec 2001 13:08:25 -0000 X-Priority: 3 X-MSMail-Priority: Normal Received: (qmail 28638 invoked from network); 30 Dec 2001 13:08:23 -0000 X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1106 Received: from unknown (HELO post.thorcom.com) (212.172.148.70) by warrior.services.quay.plus.net with SMTP; 30 Dec 2001 13:08:23 -0000 Received: from majordom by post.thorcom.com with local (Exim 3.33 #2) id 16Kfed-0004lU-00 for rsgb_lf_group-outgoing@blacksheep.org; Sun, 30 Dec 2001 13:05:31 +0000 Received: from imo-m03.mx.aol.com ([64.12.136.6]) by post.thorcom.com with esmtp (Exim 3.33 #2) id 16Kfeb-0004lJ-00 for rsgb_lf_group@blacksheep.org; Sun, 30 Dec 2001 13:05:29 +0000 Received: from MarkusVester@aol.com by imo-m03.mx.aol.com (mail_out_v31_r1.9.) id l.122.9e3b3cb (3852) for ; Sun, 30 Dec 2001 08:04:39 -0500 (EST) From: MarkusVester@aol.com Message-ID: <122.9e3b3cb.29606ae7@aol.com> Date: Sun, 30 Dec 2001 08:04:39 EST Subject: LF: Band full ? To: rsgb_lf_group@blacksheep.org MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII; format=flowed Content-Transfer-Encoding: 8bit X-Mailer: AOL 4.0.i for Windows 95 sub 72 Precedence: bulk Reply-To: rsgb_lf_group@blacksheep.org X-Listname: rsgb_lf_group Sender: Hi transatlantic gang, Band full? No, I believe there is plenty of space, it's just that we may have to move a little closer: QRSS or DFCW watched with 10 mHz resolution could leasurely be spaced at 100 mHz intervals. As the level differences between different Eu sigs seen in America will hardly exceed 15 dB, spectral widening during the keying is not a problem. Propagational doppler spread should also be less than 10mHz (though there has been one unexplained observation of wide doppler on a ZL-P29 LF path, not sure whether this was real). So it all becomes only a question of frequency accuracy and stability. Some stations (e.g. BMU, FTC, YXM and hopefully myself) are within 10mHz of stated freq (10^-7), which requires a calibrated OCXO or a very good TCXO. All others I have seen lately apparently use standard <1ppm crystal oscillators and have drifted less than 50mHz, which still is good enough. Only those rigs generating LF by mixing two independent HF xtals are probably not stable enough for real narrowband work. 7fsk must be regarded as a special case. In my opinion, much narrower tone spacings (20 to 50 mHz) should be preferred, and could even improve legibility because the sequence can be connected visually much easier. Though I don't particularly favor the thought of "frequency ownership" (still the anarchist in me, at age 43?), I agree that allocations will make life easier, and the receiving side can associate T-grade traces to their owners. So some 30 stations could work in a 60s-Argo slot in parallel. (Btw I do prefer the "90s slow" setting with equal frequency resolution.Temporal resolution is anyhow limited by FFT bandwidth, the slower display simply saves screen space.) And if that were not enough, we might eventually have to ask Alberto for a higher window. 73 es have a nice sunny sunday de Markus, DF6NM