{"id":7895,"date":"2013-07-18T14:08:56","date_gmt":"2013-07-18T14:08:56","guid":{"rendered":"https:\/\/rsgb.org\/main\/?page_id=7895"},"modified":"2023-03-09T23:52:25","modified_gmt":"2023-03-09T23:52:25","slug":"uk-5-mhz-beacon-chain","status":"publish","type":"page","link":"https:\/\/rsgb.org\/main\/operating\/band-plans\/hf\/5mhz\/uk-5-mhz-beacon-chain\/","title":{"rendered":"UK 5MHz Beacon Chain"},"content":{"rendered":"<p><strong>The original UK 5MHz experiment used three time-multiplexed propagation studies beacons, operating on 5.290 MHz and became operational in mid-2003. The last system closed in March-2023.<\/strong><\/p>\n<p>The official 5MHz Experiment they supported has concluded having achieved it aims in supporting propagation research and WRC-15.<\/p>\n<p>Regarding the current status of the UK 5MHz Beacons:-<\/p>\n<ul>\n<li><strong>GB3ORK<\/strong> was upgraded in July 2017 and added JT9A to its transmission. It was the last operational system, closing in Mar-2023 when its licence expired<\/li>\n<li><strong>GB3RAL<\/strong> had local site issues and its licence lapsed in Apr-2017<\/li>\n<li><strong>GB3WES<\/strong> ceased operations in Mar-2020 when its licence expired<\/li>\n<\/ul>\n<p><img loading=\"lazy\" decoding=\"async\" style=\"border-style: none\" src=\"https:\/\/rsgb.org\/main\/files\/2018\/10\/300px_fine_dotted_line-300x3.png\" alt=\"300px_fine_dotted_line\" width=\"300\" height=\"3\" \/><\/p>\n<h3>Background<\/h3>\n<p><strong>GB3RAL<\/strong> became operational in mid-2003, located at the Rutherford Appleton Laboratories, Oxfordshire, at IO91IN.<\/p>\n<p><strong>GB3WES<\/strong>, located in Cumbria at IO84QN, went live on 30 October 2004<\/p>\n<p><strong>GB3ORK<\/strong>, located on the Orkney Isles at IO89JA, went live at 0000z on 3 December 2004<\/p>\n<p><strong>Power:<\/strong> All three beacons used a nominal power of 10W<\/p>\n<p><strong>Antennas: <\/strong>GB3RAL employed a dipole aerial, GB3WES an inverted V dipole and GB3ORK used a 90ft long inverted V dipole, 21ft high in the centre, feed with a 1:1 current balun, orientation E-W.<\/p>\n<p><strong>Timing:<\/strong> For the first 30 seconds the three beacons followed the transmit sequence described by the following diagram:-<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" class=\"wp-image-7896 size-full aligncenter\" title=\"5 MHz Beacon Sequence\" src=\"https:\/\/rsgb.org\/main\/files\/2013\/07\/5-mhz-beacon-sequence.gif\" alt=\"5 MHz Beacon Sequence\" width=\"600\" height=\"400\" \/><\/p>\n<p>GB3RAL transmissions started on the hour, 15, 30 and 45 minutes past the hour with the call sign being sent by CW at full power.<\/p>\n<p>This is followed by a short period at full power (10W) before the transmission steps down by 6dB every second.<\/p>\n<p>After nine steps the power resumes to 10W and the nine step sequence begins again.<\/p>\n<p>From this point onwards the three beacons are different:<\/p>\n<ul>\n<li>GB3RAL transmits a PSK31 identifier<\/li>\n<li>GB3WES finishes transmission<\/li>\n<li>GB3ORK transmits a 0.5mS pulse sequence at a prf of 40 Hz at full power. This is to allow a specialist measurement of multipath and Doppler shifts to be measured along the path.<\/li>\n<\/ul>\n<p>The transmit sequence for GB3WES and GB3ORK is similar except that GB3WES starts transmissions one minute later than GB3RAL, and GB3ORK two minutes later than GB3RAL.<\/p>\n<p>Note that the short 100mS gaps between steps has only been implemented in the keying sequence for GB3WES and GB3ORK.<\/p>\n<p>The short transmission gap is there is improve readability of the steps.<\/p>\n<p>Thus the transmit sequence for the beacons are:<\/p>\n<table style=\"height: 389px\" border=\"0\" width=\"100%\" cellpadding=\"0\">\n<tbody>\n<tr>\n<td width=\"165\"><b>Minutes past each hour<\/b><\/td>\n<td width=\"425\"><b>Call sign<\/b><\/td>\n<\/tr>\n<tr>\n<td>00<\/td>\n<td>GB3RAL<\/td>\n<\/tr>\n<tr>\n<td>01<\/td>\n<td>GB3WES<\/td>\n<\/tr>\n<tr>\n<td>02<\/td>\n<td>GB3ORK<\/td>\n<\/tr>\n<tr>\n<td>15<\/td>\n<td>GB3RAL<\/td>\n<\/tr>\n<tr>\n<td>16<\/td>\n<td>GB3WES<\/td>\n<\/tr>\n<tr>\n<td>17<\/td>\n<td>GB3ORK<\/td>\n<\/tr>\n<tr>\n<td>30<\/td>\n<td>GB3RAL<\/td>\n<\/tr>\n<tr>\n<td>31<\/td>\n<td>GB3WES<\/td>\n<\/tr>\n<tr>\n<td>32<\/td>\n<td>GB3ORK<\/td>\n<\/tr>\n<tr>\n<td>45<\/td>\n<td>GB3RAL<\/td>\n<\/tr>\n<tr>\n<td>46<\/td>\n<td>GB3WES<\/td>\n<\/tr>\n<tr>\n<td>47<\/td>\n<td>GB3ORK<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p>The beacons have several features that were innovative when they were designed in 2003.<\/p>\n<p>They include GPS time and frequency synchronization as well as fairly accurate 6dB transmit stepping.<\/p>\n<p>Write ups of their design and construction can be found below:-<\/p>\n<ul>\n<li><strong>Beacon Design: <a href=\"https:\/\/rsgb.org\/main\/files\/2013\/07\/June-2005.pdf\" target=\"_blank\" rel=\"noopener noreferrer\">Part-1 &#8211; June 2005<\/a><\/strong> (3-page\/188KB PDF) <em>RadCom<\/em><\/li>\n<li><strong>Beacon Design: \u00a0Part-2 \u00a0<a href=\"https:\/\/rsgb.org\/main\/files\/2013\/07\/July-2005.pdf\" target=\"_blank\" rel=\"noopener noreferrer\">July 2005<\/a><\/strong> (2-page\/154KB PDF) \u00a0<em>RadCom<\/em><\/li>\n<li><strong>Background: <a href=\"https:\/\/rsgb.org\/main\/files\/2020\/02\/5MHz-Experiment_G3WKL.pdf\">5MHz Experiment<\/a> <\/strong>(18-slides\/222KB PDF) John\u00a0<em>G3WKL, RSGB 5WG<\/em><\/li>\n<\/ul>\n<h3>Auto-monitoring software<\/h3>\n<p>Peter Martinez, G3PLX wrote a freeware Windows program in 2003, which automates the process of monitoring and logging the reception of the three beacons.<\/p>\n<p>The program carries out the function of a 1Hz bandwidth audio filter but can compensate for moderate amounts of frequency drift in the receiver and timing drift in the computer clock.<\/p>\n<p>The monitoring program can either process audio from a conventional receiver or else the two I &amp; Q audio channels from a direct conversion receiver.<\/p>\n<p>The program also provides COM port switching for external devices, e.g. aerial switching, WSPR beacon, etc.<\/p>\n<h3>Acknowledgements<\/h3>\n<p>In putting together this beacon chain it is important to recognise the efforts put into the project by the three beacon keepers:-<\/p>\n<ul>\n<li>Mike Willis, G0MJW and\u00a0RAL for hosting GB3RAL,<\/li>\n<li>John Linford, G3WGV for hosting GB3WES and<\/li>\n<li>John Grieve, aka Donnie, GM0HTH for hosting GB3ORK<\/li>\n<li>Andy Talbot, G4JNT, also needs special mention for designing and building the beacons &#8211; and&#8230;<\/li>\n<li>Peter Martinez, G3PLX, for his untiring work to support the beacon project with free automated beacon-monitoring software, as well as the more specialist work involved in the study of Doppler and multipath propagation from the beacons<\/li>\n<\/ul>\n<p>Our thanks are also due to\u00a0<strong><a href=\"http:\/\/www.yaesu.co.uk\/\" target=\"_blank\" rel=\"noopener noreferrer\">Yaesu(UK)<\/a><\/strong>\u00a0and\u00a0<strong><a href=\"http:\/\/www.smc-comms.com\/\" target=\"_blank\" rel=\"noopener noreferrer\">SMC<\/a><\/strong>\u00a0for their support with the initial phase of the beacons, and not least to <a href=\"http:\/\/www.ofcom.org.uk\/\" target=\"_blank\" rel=\"noopener noreferrer\"><strong>Ofcom<\/strong><\/a>\u00a0for the necessary unattended beacon licences to enable these beacons to operate.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>The original UK 5MHz experiment used three time-multiplexed propagation studies beacons, operating on 5.290 MHz and became operational in mid-2003. The last system closed in March-2023. The official 5MHz Experiment they supported has concluded having achieved it aims in supporting propagation research and WRC-15. Regarding the current status of the UK 5MHz Beacons:- GB3ORK was [&hellip;]<\/p>\n","protected":false},"author":10,"featured_media":0,"parent":6068,"menu_order":1,"comment_status":"closed","ping_status":"closed","template":"","meta":{"footnotes":""},"class_list":["post-7895","page","type-page","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/rsgb.org\/main\/wp-json\/wp\/v2\/pages\/7895","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/rsgb.org\/main\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/rsgb.org\/main\/wp-json\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/rsgb.org\/main\/wp-json\/wp\/v2\/users\/10"}],"replies":[{"embeddable":true,"href":"https:\/\/rsgb.org\/main\/wp-json\/wp\/v2\/comments?post=7895"}],"version-history":[{"count":0,"href":"https:\/\/rsgb.org\/main\/wp-json\/wp\/v2\/pages\/7895\/revisions"}],"up":[{"embeddable":true,"href":"https:\/\/rsgb.org\/main\/wp-json\/wp\/v2\/pages\/6068"}],"wp:attachment":[{"href":"https:\/\/rsgb.org\/main\/wp-json\/wp\/v2\/media?parent=7895"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}