{"id":2677,"date":"2016-12-13T22:11:58","date_gmt":"2016-12-13T22:11:58","guid":{"rendered":"http:\/\/www.tsgarc.uk\/?p=2677"},"modified":"2016-12-13T22:12:54","modified_gmt":"2016-12-13T22:12:54","slug":"icom-ic-7100-and-gnss-receiver","status":"publish","type":"post","link":"https:\/\/www.tsgarc.uk\/?p=2677","title":{"rendered":"Icom IC-7100 and GNSS Receiver"},"content":{"rendered":"

\"ICOM<\/a>For some time I\u2019ve been thinking about replacing the IC-706Mk2g<\/a> in my pickup with a newer radio.\u00a0 The obvious choice was a\u00a0IC-7100<\/a> as it has all the same connectors, including that for the AH-4<\/a> auto-coupler. \u00a0As a bonus the radio is the same size and uses the same mount bracket. \u00a0I had held off getting the IC-7100<\/a> for quite some time as I wasn\u2019t convinced its \u2018L\u2019 shaped head was suitable\u00a0for mobile use.\u00a0 Having owned it for a month I\u2019m still not convinced but do like the radio and its odd shaped head unit is growing on me.<\/p>\n

\"IC-7100<\/a>D-Star was not a selection factor for\u00a0the IC-7100\u00a0purchase, but since the radio had this capability it seemed wrong not to give it a go \ud83d\ude42 \u00a0D-Star could be a news item in its own right, but suffice to say my experience thus far is not great.\u00a0 Several of the repeaters around the Bristol area have either migrated to alternate digital systems, don\u2019t seem to be operational or are not connected to the D-Star network which undermines usefulness. \u00a0As the memory channels in the radio are programmed with many, many repeaters, selecting one in the vicinity of my location whilst driving was\u00a0tricky. \u00a0But IC-7100 has the ability to receive NMEA<\/a> data from a GNSS<\/a> receiver and use geolocation information to identify repeaters in the vicinity of the radio that may be used.\u00a0 I was keen to give this a go but needed a source of NMEA<\/a> data.\u00a0 Unfortunetly, the IC-7100 does not contain a GNSS<\/a> receiver but it does present a three-pole, 3.5mm NMEA<\/a> interface. \u00a0The pins are: Ground, TxData and RxData.<\/p>\n

Locating a suitable GNSS<\/a> receiver was\u00a0not as\u00a0simple as it should have been\u00a0as most nowadays implement either Bluethooth or USB as the physical interface rather than NMEA<\/a>.\u00a0 However, some research identified the G-STAR IV<\/a> from Globalsat<\/a>. \u00a0It does have an RS-232 physical interface and as NMEA\u00a0is compatible with RS-232 at the physical layer\u00a0it worked fine. \u00a0However, the G-Star IV<\/a>\u00a0used a 6-pin mini-din plug rather than the more conventional 9-pin \u2018D\u2019 connector associated with RS-232 plus it\u00a0required a +5V DC, 80mA power feed.<\/p>\n

Clearly, it was necessary to construct an interface between the radio and the G-STAR IV<\/a> receiver not only because the physical connectors were different but because a power feed\u00a0was needed. \u00a0After some investigation, I decided to use the +12V DC power from the truck batteries reduced to the level required using a small voltage regulator, 7805, circuit. \u00a0This worked great providing a rock-sold power feed. \u00a0A byproduct of connecting to the truck batteries was\u00a0that the power was\u00a0always ‘on’ and thus the GNSS receiver\u00a0was powered and consuming current. \u00a0So, my design included a power switch to remove the GNSS receiver from the power when not in use.<\/p>\n

\"IC-7100,<\/a>The interface unit was quickly assembled using a plastic case, suitable connectors and a small piece of Veroboard<\/a> onto which the voltage regulator and some electrostatic smoothing capacitors were attached. \u00a0A small red LED was also included for diagnostic purposes. \u00a0This lit when power was being provided to the GNSS<\/a> receiver. \u00a0Once assembled it was tested on the bench using an oscilloscope to monitor the resulting NMEA<\/a> data. \u00a0This data appeared as a square wave of the correct frequency so I had a high confidence that all was working well.<\/p>\n

The pictures in the article show the completed interface unit. \u00a0I’m happy to answer any questions if someone has a need for something similar.<\/p>\n

Footnote: \u00a0Everything worked great on the bench, however, on migrating the unit to the truck I realised that Icom and rather annoyingly used a 3-pole, 2.5mm connector for the GNSS<\/a> receiver. \u00a0This meant the whole project was delayed whilst I sourced a connector which as it was at a weekend –\u00a0Maplin Electronics<\/a>. \u00a0Making the cable really was a short job but it took another 4 to 5 hours to get everything working reliably as there was a weird mechanical failure on the centre tip of the 2.5mm connector resulting in an intermittent connection. \u00a0I really don’t like Maplin<\/a> these days and this experience only served to reinforce my view that their products are of the lowest quality.<\/p>\n

Andrew<\/em>
\n G0RVM<\/em><\/p>\n","protected":false},"excerpt":{"rendered":"

For some time I\u2019ve been thinking about replacing the IC-706Mk2g in my pickup with a newer radio.\u00a0 The obvious choice was a\u00a0IC-7100 as it has all the same connectors, including that for the AH-4 auto-coupler. \u00a0As a bonus the radio … Continue reading →<\/span><\/a><\/p>\n","protected":false},"author":7,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"_monsterinsights_skip_tracking":false,"_monsterinsights_sitenote_active":false,"_monsterinsights_sitenote_note":"","_monsterinsights_sitenote_category":0,"_jetpack_memberships_contains_paid_content":false,"footnotes":"","jetpack_publicize_message":"","jetpack_publicize_feature_enabled":true,"jetpack_social_post_already_shared":false,"jetpack_social_options":{"image_generator_settings":{"template":"highway","default_image_id":0,"font":"","enabled":false},"version":2}},"categories":[5],"tags":[],"class_list":["post-2677","post","type-post","status-publish","format-standard","hentry","category-news"],"aioseo_notices":[],"jetpack_publicize_connections":[],"jetpack_featured_media_url":"","jetpack_sharing_enabled":true,"_links":{"self":[{"href":"https:\/\/www.tsgarc.uk\/index.php?rest_route=\/wp\/v2\/posts\/2677","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.tsgarc.uk\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.tsgarc.uk\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.tsgarc.uk\/index.php?rest_route=\/wp\/v2\/users\/7"}],"replies":[{"embeddable":true,"href":"https:\/\/www.tsgarc.uk\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=2677"}],"version-history":[{"count":5,"href":"https:\/\/www.tsgarc.uk\/index.php?rest_route=\/wp\/v2\/posts\/2677\/revisions"}],"predecessor-version":[{"id":2683,"href":"https:\/\/www.tsgarc.uk\/index.php?rest_route=\/wp\/v2\/posts\/2677\/revisions\/2683"}],"wp:attachment":[{"href":"https:\/\/www.tsgarc.uk\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=2677"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.tsgarc.uk\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=2677"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.tsgarc.uk\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=2677"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}