{"id":1068,"date":"2013-03-12T10:37:03","date_gmt":"2013-03-12T06:37:03","guid":{"rendered":"https:\/\/mpc-oman.com\/?page_id=1068"},"modified":"2013-03-12T10:37:03","modified_gmt":"2013-03-12T06:37:03","slug":"absolute-power-measurement","status":"publish","type":"page","link":"https:\/\/mpc-oman.com\/?page_id=1068","title":{"rendered":"Absolute Power Measurement"},"content":{"rendered":"<h1><strong>10A: <\/strong>Absolute Power Measurement<\/h1>\n<div align=\"right\">Written by Bruce Roberson 97-03. \u00a9 Kingfisher International<\/div>\n<h2><a href=\"http:\/\/www.kingfisherfiber.com\/Application-Notes\/10-Fiber-Optic-Test-Procedures.aspx\"> <img decoding=\"async\" alt=\"prev\" src=\"http:\/\/www.kingfisherfiber.com\/images\/icons\/os\/previous_16x16.gif\" align=\"middle\" border=\"0\" \/><\/a> <a> <img decoding=\"async\" alt=\"add to favourites\" src=\"http:\/\/www.kingfisherfiber.com\/images\/icons\/os\/fav_16x16.gif\" align=\"middle\" border=\"0\" \/> <\/a> <a> <img decoding=\"async\" alt=\"print\" src=\"http:\/\/www.kingfisherfiber.com\/images\/icons\/printer\/printer.gif\" align=\"middle\" border=\"0\" \/> <\/a> <a href=\"http:\/\/www.kingfisherfiber.com\/Application-Notes\/10B-Basic-Fiber-Loss-Test-Procedure.aspx\"> <img decoding=\"async\" alt=\"next\" src=\"http:\/\/www.kingfisherfiber.com\/images\/icons\/os\/next_16x16.gif\" align=\"middle\" border=\"0\" \/><\/a> Introduction<\/h2>\n<p>The typical application for this is to measure the emitted light level of an transmitter, or the power going into a receiver.<\/p>\n<p>When doing this, remember that if the transmitter is modulated at 50% duty cycle, the average power reading will be lower than the peak power by 50%, eg 3 dB. It is not recommended to perform power measurements on transmitters modulating slower than about 0.1 Mbaud, or inaccurate readings can result.<\/p>\n<p>The power meter must be rated to measure the peak instantaneous power, or detector saturation may result in low optical power measurements.<\/p>\n<p>Safety precautions must match the possible source power levels. With high power systems, this a significant issue.<\/p>\n<ul>\n<li>Turn on the instruments ,and allow to warm up. Clean and inspect the patch leads.<\/li>\n<li>Use a matching patch lead to connect the instruments to the device being tested.<\/li>\n<li>If testing a laser, use of an APC connector plugged into the power meter will reduce optical reflections, and so generally improve measurement accuracy.<\/li>\n<li>A multimode measurement requires a mandrel wrap if measuring source power against specifications. If measuring the actual receiver power on an installed system at the receiver end, do not generally use a mandrel wrap.<\/li>\n<li>Set the meter to the correct wavelength, in absolute ( dBm ) mode. It now displays the absolute power level in dBm.<\/li>\n<\/ul>\n<h3>How to calculate dBm<\/h3>\n<p>The linear-to-dBm calculation method is:<\/p>\n<p>dBm = 10 log ( P1 \/ P2 )<\/p>\n<p>where P1 = measured power level ( eg in mWatts )<br \/>\nP2 = reference power level, which is 1 mW<\/p>\n<p>More information and an Excel log\/linear conversion utility available in <a href=\"http:\/\/www.kingfisherfiber.com\/Application-Notes\/01-dB-dBm-Definition-Calculator.aspx\">A01<\/a><\/p>\n","protected":false},"excerpt":{"rendered":"<p>10A: Absolute Power Measurement Written by Bruce Roberson 97-03. \u00a9 Kingfisher International Introduction The typical application for this is to measure the emitted light level of an transmitter, or the power going into a receiver. When doing this, remember that if the transmitter is modulated at 50% duty cycle, the average power reading will be [&hellip;]<\/p>\n","protected":false},"author":1,"featured_media":0,"parent":1065,"menu_order":0,"comment_status":"open","ping_status":"open","template":"","meta":[],"_links":{"self":[{"href":"https:\/\/mpc-oman.com\/index.php?rest_route=\/wp\/v2\/pages\/1068"}],"collection":[{"href":"https:\/\/mpc-oman.com\/index.php?rest_route=\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/mpc-oman.com\/index.php?rest_route=\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/mpc-oman.com\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/mpc-oman.com\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=1068"}],"version-history":[{"count":1,"href":"https:\/\/mpc-oman.com\/index.php?rest_route=\/wp\/v2\/pages\/1068\/revisions"}],"predecessor-version":[{"id":1070,"href":"https:\/\/mpc-oman.com\/index.php?rest_route=\/wp\/v2\/pages\/1068\/revisions\/1070"}],"up":[{"embeddable":true,"href":"https:\/\/mpc-oman.com\/index.php?rest_route=\/wp\/v2\/pages\/1065"}],"wp:attachment":[{"href":"https:\/\/mpc-oman.com\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=1068"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}