Return-Path: Received: (qmail 23384 invoked from network); 17 May 2000 00:05:30 -0000 Received: from unknown (HELO post.thorcom.com) (212.172.148.70) by grants.core.plus.net.uk with SMTP; 17 May 2000 00:05:30 -0000 Received: from majordom by post.thorcom.com with local (Exim 3.02 #1) id 12rrFc-0004YL-00 for rsgb_lf_group-outgoing@blacksheep.org; Wed, 17 May 2000 00:59:48 +0100 X-Priority: 3 X-MSMail-Priority: Normal Received: from imo12.mx.aol.com ([152.163.225.2]) by post.thorcom.com with esmtp (Exim 3.02 #1) id 12rrFZ-0004VO-00 for rsgb_lf_group@blacksheep.org; Wed, 17 May 2000 00:59:45 +0100 Received: from MarkusVester@aol.com by imo12.mx.aol.com (mail_out_v26.7.) id l.a9.5a8fc44 (3848) for ; Tue, 16 May 2000 19:58:46 -0400 (EDT) X-MimeOLE: Produced By Microsoft MimeOLE V6.00.2800.1106 From: MarkusVester@aol.com Message-ID: Date: Tue, 16 May 2000 19:58:45 EDT Subject: LF: CFH... why wait for winter? 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 64 Precedence: bulk Reply-To: rsgb_lf_group@blacksheep.org X-Listname: rsgb_lf_group Sender: Hello group, yesterday night, the qrn seemed to be fairly moderate, so I decided to start spectrogram at 22:00 UT (5513 Hz, 512 pts, 30 s dwell, 128 averages, resolution bandwidth with windowing appr. 14 Hz). In the morning, I was quite surprised to see a fat trace of CFH 137.0 kHz beginning at 00:10. A first maximum occured around 00:55 with about 11 dBuV/m/14Hz, then the signal dived down for 15 minutes before it came back with similar strength. After staying fairly constant for about 1.5 h, it peaked to 13 dBuV/m/14Hz from 02:55 to 03:10, then decayed and became invisible around 04:10. SVX from Greece was strong all night until 02:40, with a pronounced double-minimum at 03:00 and 03:14 around sunrise. Starting at 23:45, there was another unidentified narrowband signal with dx-like fading on 136.3 kHz, up to 10 dBuV/m. The noise between the statics was around -10 dBuV/m/14Hz during the night, decreasing by 5 dB with daylight. For the calculation of signal strength, I have found a ratio of 7 dB between CFH's observed power density in 14 Hz and its total power, corresponding to an effective modulation bandwidth of 70 Hz. So the actual field-strength would be 20 dBuV/m in the maximum. Reducing the noise density to 1 Hz, I would see -10-11.5 = -21.5 dB/Hz, resultimg in an SNR of 41.5dB/Hz. The ERP of CFH is said to be around 10 kW, 40 dB above an amateur station's limit. That would leave us with 1.5 dB SNR in 1 Hz, or 11.5 dB with 10 s dots in 0.1 Hz, even here in the middle of Europe. In other words: Had we tried last night, we would have made it across! BTW: Comparable observations in winter and early spring had shown a quite similar field strength, it was only the time window of common darkness which was much longer. Cheers Markus, DF6NM