Return-Path: Received: (qmail 19440 invoked from network); 17 May 2001 09:47:57 -0000 Received: from unknown (HELO warrior-inbound.servers.plus.net) (212.159.14.227) by excalibur.plus.net with SMTP; 17 May 2001 09:47:57 -0000 Received: (qmail 3451 invoked from network); 17 May 2001 09:47:20 -0000 Received: from unknown (HELO post.thorcom.com) (212.172.148.70) by warrior with SMTP; 17 May 2001 09:47:20 -0000 Received: from majordom by post.thorcom.com with local (Exim 3.16 #2) id 150KGG-0008Of-00 for rsgb_lf_group-outgoing@blacksheep.org; Thu, 17 May 2001 10:40:00 +0100 Received: from latimer.mail.uk.easynet.net ([195.40.1.40]) by post.thorcom.com with esmtp (Exim 3.16 #2) id 150KGF-0008Oa-00 for rsgb_lf_group@blacksheep.org; Thu, 17 May 2001 10:39:59 +0100 Received: from ericadodd (tnt-3-235.easynet.co.uk [195.40.202.235]) by latimer.mail.uk.easynet.net (Postfix) with SMTP id CB64053F7B for ; Thu, 17 May 2001 10:39:25 +0100 (BST) Message-ID: <000201c0deb5$c2989400$ebca28c3@ericadodd> From: "g3ldo" To: rsgb_lf_group@blacksheep.org References: <3.0.1.16.20010516103336.2b5f0e90@mail.cc.kuleuven.ac.be> <5.0.2.1.2.20010516221555.00a07cc0@mail.pncl.co.uk> Subject: LF: Re: LF Prop. Date: Thu, 17 May 2001 09:51:12 +0100 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 5.50.4522.1200 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: Walter G3JKV said:. > FWIW, we had most problems with Decca skywave interference at sunspot minimum. There is this thing called LUF (Lowest Usable Frequency). Not much in ham literature about it but from Bill Orr's Radio Handbook it depends on transmitter erp and atmospheric noise. Generally speaking the LUF can be lowered (at HF) by approximately 2MHz for each 10dB increase in erp. However it is obvious that the LUF changes throughout the day. Does it follow the MUF? If it does then it will follow the sunspot cycle. Are there any average graphs of LUF? I understand that most data available is for commercial link reliability and ignores the esoteric magnetic effects that we have been using on LF. Regards, Peter, G3LDO e-mail Web