{"id":6858,"date":"2020-02-11T18:42:15","date_gmt":"2020-02-11T18:42:15","guid":{"rendered":"https:\/\/www.use-snip.com\/kb\/?post_type=ht_kb&#038;p=6858"},"modified":"2020-07-26T23:47:32","modified_gmt":"2020-07-26T23:47:32","slug":"key-consideration-when-creating-single-baseline-near-streams-with-the-snip-ntrip-caster","status":"publish","type":"ht_kb","link":"https:\/\/www.use-snip.com\/kb\/knowledge-base\/key-consideration-when-creating-single-baseline-near-streams-with-the-snip-ntrip-caster\/","title":{"rendered":"Considerations for Creating NEAR Streams"},"content":{"rendered":"<p>This article covers some key considerations when creating Single Baseline <strong>NEAR&#x2122;<\/strong> streams with the<span style=\"color: #0000ff;\"><strong> SNIP<\/strong><\/span> NTRIP Caster.\u00a0 A <a href=\"https:\/\/www.use-snip.com\/kb\/knowledge-base\/nearest-streams-tab\/\" target=\"_blank\" rel=\"noopener noreferrer\"><strong>NEAR<\/strong> stream<\/a> is a type of of RTK Network data stream where each end user (the rovers or <a href=\"https:\/\/www.use-snip.com\/kb\/knowledge-base\/question-what-is-an-ntrip-client\/\" target=\"_blank\" rel=\"noopener noreferrer\">NTRIP Clients<\/a>) connects to a single mountPt (often with the word <em>NEAR<\/em> in its name) and then the <span style=\"color: #0000ff;\"><strong>SNIP<\/strong><\/span> <a href=\"https:\/\/www.use-snip.com\/kb\/knowledge-base\/question-what-is-an-ntrip-caster\/\" target=\"_blank\" rel=\"noopener noreferrer\">NTRIP Caster<\/a> automatically connects that user to be best (often the closest) Base Station meeting it&#8217;s individual needs.\u00a0 As the rover moves, this process is repeated, seamlessly connecting the user to the best Base Station at all times.\u00a0 This results in optimal single baseline data streams with less measurement noise than various virtual methods. And the end user need not become familiar with the names and locations of different Base Stations in the Caster Table.\u00a0 <span style=\"color: #0000ff;\"><strong>SNIP<\/strong><\/span> supports a wide range of feature and settings to create various <strong>NEAR<\/strong> streams for different user application.<\/p>\n<h2 style=\"text-align: center;\">Key Considerations for Creating and using NEAR Streams<\/h2>\n<p>In order to use a NEAR stream a small amount of planning is required, both on the NTRIP Caster Side and on the rover devices that will connect to it.\u00a0 The primary requirements and considerations are listed below.<\/p>\n<h3>On the Rover side:<\/h3>\n<ul>\n<li>Each rover\/NTRIP Client <u>must<\/u> report its estimate of position with the common <a href=\"https:\/\/www.use-snip.com\/kb\/knowledge-base\/nmea-gga-strings-in-ntrip-clients\/\">NMEA-183 $GPGGA<\/a> sentence.\u00a0 This information is used (each time it is sent) to determine what Base Station data stream, from that NEAR mountPts pool of base stations,\u00a0 to send to that rover device.<\/li>\n<li>Any rover\/NTRIP Client that reports a position outside the service area of the NEAR pool is disconnected because there is no suitable data to send to it.<\/li>\n<li>Any rover\/NTRIP Client that does not report its position within a reasonable period of time (~20 seconds or so) is disconnected. Often such users state they are &#8220;getting no data&#8221; because of this.<\/li>\n<li>The rover\/NTRIP Client must report its position at least one time. It is common to repeat this every 5~30 seconds, but not required.<\/li>\n<li>The rover\/NTRIP Client can report its position with any mix of NTRIP Rev1 and Rev2 protocol formats it desires.<\/li>\n<li>The first five NMEA-183 $GPGGA sentences seen for any rover\/NTRIP Client connection are displayed on the console log (enable <em>verbose<\/em> logging to view) .\u00a0 <span style=\"color: #008000;\"><strong>Tip:\u00a0<\/strong> <\/span>If you do not see such messages, the rover\/NTRIP Client is not sending the required data.<\/li>\n<li>If one or more of your rover\/NTRIP Client sends ill-formed NMEA-183 $GPGGA sentences, enable the checkbox found on the Caster \/ Clients tab to instruct <span style=\"color: #0000ff;\"><strong>SNIP<\/strong><\/span> to be more relaxed in its decoding.<\/li>\n<li>The most recent NMEA-183 $GPGA data for any client can be seen in the <a href=\"https:\/\/www.use-snip.com\/kb\/knowledge-base\/viewing-current-users\/\" target=\"_blank\" rel=\"noopener noreferrer\"><i>Display Connected Users <\/i><\/a>window along with the Base Station to which it is assigned.<\/li>\n<li>The movement reported from recent NMEA data for any client can be viewed on the <a href=\"https:\/\/www.use-snip.com\/kb\/knowledge-base\/support-for-basic-mapping\/\" target=\"_blank\" rel=\"noopener noreferrer\">MAP display<\/a>, and this data can be sent out on the AVL server (see the <a href=\"https:\/\/www.use-snip.com\/kb\/knowledge-base\/the-avl-tab\/\" target=\"_blank\" rel=\"noopener noreferrer\">AVL tab<\/a>) for use by various 3rd party tools.<\/li>\n<\/ul>\n<h3>On the SNIP Caster side:<\/h3>\n<ul>\n<li>Set up the NEAR pool with these general instructions:<br \/>\n<a class=\"moz-txt-link-freetext\" href=\"https:\/\/www.use-snip.com\/kb\/knowledge-base\/nearest-streams-tab\/\">https:\/\/www.use-snip.com\/kb\/knowledge-base\/nearest-streams-tab\/<\/a><\/li>\n<li>In the knowledge base the <strong>NEAR<\/strong> features have their own section:<br \/>\n<a class=\"moz-txt-link-freetext\" href=\"https:\/\/www.use-snip.com\/kb\/article-categories\/nearest-caster\/\">https:\/\/www.use-snip.com\/kb\/article-categories\/nearest-caster\/<\/a><\/li>\n<li>Each <strong>NEAR<\/strong> stream maintains a &#8220;pool&#8221; of Base Stations which meet its requirements for specific message content, location, types and numbers of satellites, and quality.\u00a0 When a user device provides its own location, one of the members of the pool is selected.<\/li>\n<li>Keep in mind the coverage area of the near pool is determined by the stations used at that time. Therefore the specific coverage region may change as stations come and go from the pool.<\/li>\n<li>If you observe positional &#8220;jumps&#8221; when a given rover connects from one Base Station to another, this almost certainly indicates that your Base Stations are not aligned to a common frame of reference.\u00a0 Use a post-processing tool like <a href=\"https:\/\/www.use-snip.com\/kb\/knowledge-base\/post-processing-your-measurements-by-opus-and-others\/\" target=\"_blank\" rel=\"noopener noreferrer\">OPUS<\/a> to precisely determine each Base position and confirm this is in fact what that Base is sending using <span style=\"color: #0000ff;\"><strong>SNIP<\/strong><\/span>&#8216;s <a href=\"https:\/\/www.use-snip.com\/kb\/knowledge-base\/message-monitoring\/\" target=\"_blank\" rel=\"noopener noreferrer\">RTCM message viewer<\/a> or various <span style=\"color: #0000ff;\"><strong>SNIP<\/strong><\/span> tool tips.\u00a0 If your network is made up of some Base Stations operated by another party (where you cannot set the station location values or the datum used), use a <a href=\"https:\/\/www.use-snip.com\/kb\/knowledge-base\/pfat-adjusting-datum-network\/\" target=\"_blank\" rel=\"noopener noreferrer\"><em><strong>PFAT<\/strong><\/em> transformation<\/a> to adjust the position to align with your other stations (see also <a href=\"https:\/\/www.use-snip.com\/kb\/knowledge-base\/pfat-translate-settings-uses\/\">this article<\/a>).<\/li>\n<li><strong>NEAR<\/strong> Pools all default to contain\u00a0 RTCM3.x message content, but you can set the content to be other data formats (CMR, uBlox, etc.), this is a <span style=\"color: #993300;\"><em><strong>Pro<\/strong><\/em><\/span> model feature only.<\/li>\n<li>The value set for &#8220;Max Baseline Distance&#8221; determines the farthest distance between a rover and a Base Station that will be allowed. The default is set to 60km but this value may need to be increased when supporting rover devices which are at the edge of your network coverage area. For further details see <a href=\"https:\/\/www.use-snip.com\/kb\/knowledge-base\/nearest-mountpt-distance-values\/\" target=\"_blank\" rel=\"noopener noreferrer\">this article<\/a>.<\/li>\n<li>If you desire to have rover devices connect to a given closest Base Station and then &#8220;stay&#8221; on that Base Station even when moving to another station that may be slightly closer, simply increase the <strong><em>Hysteresis Distance<\/em><\/strong> value (which defaults to 2km).\u00a0 The moving rover will not be switched over to the new nearest Base Station until the hysteresis value has been exceeded.\u00a0 This has value in some Precision Ag applications. Regardless of this value, should the Base Station go offline or have problems detected with it, all users connected to it are then reassigned to the best Base Station among the remaining ones for their individual needs.<\/li>\n<li>The values set in Stream Content settings (see <a href=\"https:\/\/www.use-snip.com\/kb\/knowledge-base\/nearest-mountpt-stream-contents\/\">this article<\/a>) apply to <u>every<\/u> Base Station in the pool.\u00a0 For example if you check that &#8220;Galileo&#8221; (GAL) must be preset in the data stream, then a Base Station containing only GPS+GLO content would be excluded from that pool.<\/li>\n<li>You can also &#8220;draw a circle&#8221; around a given Lat-Long location, then set a coverage radius, and easily include all Base Stations within that region that match the specific Stream Content requirements you have set.\u00a0 This is useful where you have Base Stations in your <span style=\"color: #0000ff;\"><strong>SNIP<\/strong><\/span> Caster that cover widely separated operating areas such as both EU and Japan.<\/li>\n<li>If you have a specific set of Base Stations you wish to be in a <strong>NEAR<\/strong> pool, you can create a list of these when editing the pool settings.\u00a0 This has value where there is a need to exclude certain Base Stations for various reasons.\u00a0 See <a href=\"https:\/\/www.use-snip.com\/kb\/knowledge-base\/near-settings-using-base-station-lists\/\" target=\"_blank\" rel=\"noopener noreferrer\">this article<\/a> for further details.<\/li>\n<li>If you are running both a <strong>NEAR<\/strong> pool with legacy message content (to support older GNSS rovers) and another with MSM content, it is typical to add each type to its own list.\u00a0 You can then also hide or show the individual Base Stations in the public Caster table as you prefer.\u00a0 See these articles for further details on using <a href=\"https:\/\/www.use-snip.com\/kb\/knowledge-base\/pfat-used-create-multiple-streams\/\" target=\"_blank\" rel=\"noopener noreferrer\"><strong>PFAT<\/strong><\/a> to create either <a href=\"https:\/\/www.use-snip.com\/kb\/knowledge-base\/pfat-legacy-to-msm-messages\/\" target=\"_blank\" rel=\"noopener noreferrer\">MSM<\/a> or <a href=\"https:\/\/www.use-snip.com\/kb\/knowledge-base\/pfat-msm-to-legacy-messages\/\" target=\"_blank\" rel=\"noopener noreferrer\">legacy<\/a> message\u00a0 to use on such pools.<\/li>\n<li>The Base Stations used in the <strong>NEAR<\/strong> pools are expected to be stable and not subject to frequent short term drop-outs or corruption.\u00a0 <span style=\"color: #0000ff;\"><strong>SNIP<\/strong><\/span> measures and tracks each Base Station message stream for ~180 seconds before allowing it to be used in a pool.\u00a0 This quality checking causes a short delay when the Caster is first started to ensure suitable data.<\/li>\n<li>The <span style=\"color: #0000ff;\"><strong>SNIP<\/strong><\/span> <span style=\"color: #993300;\"><em><strong>Pro<\/strong><\/em><\/span> model allows 5 <strong>NEAR<\/strong> pools. And another near pool added for every 10th additional slot license found on the machine. The <span style=\"color: #993300;\"><em><strong>Basic<\/strong><\/em><\/span> model allows one <strong>NEAR<\/strong> pool with RTCM3.x content.<\/li>\n<li>A report summary of all the current <strong>NEAR<\/strong> pools and the stations that are used in each can be obtained with the menu item <em><strong>Reports<\/strong> <\/em>\u2192 <em><strong>All Streams<\/strong><\/em> \u2192 <em><strong>NEAR Streams Summary<\/strong><\/em>.\u00a0\u00a0\u00a0 This report is also available directly from a button on the <a href=\"https:\/\/www.use-snip.com\/kb\/knowledge-base\/the-document-viewer\/\" target=\"_blank\" rel=\"noopener noreferrer\">document viewer<\/a> tab.<\/li>\n<\/ul>\n<p>As always, setup support is only an email away when needed.<\/p>\n","protected":false},"excerpt":{"rendered":"<p>This article covers some key considerations when creating Single Baseline NEAR&#x2122; streams with the SNIP NTRIP Caster.\u00a0 A NEAR stream is a type of of RTK Network data stream where each end user (the rovers or NTRIP Clients) connects to a single mountPt (often with the word NEAR in its [&hellip;]<\/p>\n","protected":false},"author":13,"comment_status":"open","ping_status":"closed","template":"","format":"standard","meta":{"_exactmetrics_skip_tracking":false,"_exactmetrics_sitenote_active":false,"_exactmetrics_sitenote_note":"","_exactmetrics_sitenote_category":0,"footnotes":""},"ht-kb-category":[282],"ht-kb-tag":[292,461,287],"class_list":["post-6858","ht_kb","type-ht_kb","status-publish","format-standard","hentry","ht_kb_category-nearest-caster","ht_kb_tag-near","ht_kb_tag-near-pool","ht_kb_tag-nearest"],"_links":{"self":[{"href":"https:\/\/www.use-snip.com\/kb\/wp-json\/wp\/v2\/ht-kb\/6858","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.use-snip.com\/kb\/wp-json\/wp\/v2\/ht-kb"}],"about":[{"href":"https:\/\/www.use-snip.com\/kb\/wp-json\/wp\/v2\/types\/ht_kb"}],"author":[{"embeddable":true,"href":"https:\/\/www.use-snip.com\/kb\/wp-json\/wp\/v2\/users\/13"}],"replies":[{"embeddable":true,"href":"https:\/\/www.use-snip.com\/kb\/wp-json\/wp\/v2\/comments?post=6858"}],"version-history":[{"count":9,"href":"https:\/\/www.use-snip.com\/kb\/wp-json\/wp\/v2\/ht-kb\/6858\/revisions"}],"predecessor-version":[{"id":7037,"href":"https:\/\/www.use-snip.com\/kb\/wp-json\/wp\/v2\/ht-kb\/6858\/revisions\/7037"}],"wp:attachment":[{"href":"https:\/\/www.use-snip.com\/kb\/wp-json\/wp\/v2\/media?parent=6858"}],"wp:term":[{"taxonomy":"ht_kb_category","embeddable":true,"href":"https:\/\/www.use-snip.com\/kb\/wp-json\/wp\/v2\/ht-kb-category?post=6858"},{"taxonomy":"ht_kb_tag","embeddable":true,"href":"https:\/\/www.use-snip.com\/kb\/wp-json\/wp\/v2\/ht-kb-tag?post=6858"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}