{"id":1021,"date":"2014-09-24T16:43:37","date_gmt":"2014-09-24T16:43:37","guid":{"rendered":"http:\/\/www.raveon.com\/data_radio_info\/?p=1021"},"modified":"2014-09-24T16:43:37","modified_gmt":"2014-09-24T16:43:37","slug":"rssi-and-communication-range","status":"publish","type":"post","link":"https:\/\/www.raveon.com\/data_radio_info\/rssi-and-communication-range-1021\/","title":{"rendered":"RSSI and Communication Range"},"content":{"rendered":"

Radio Signal Strength Indication (RSSI)<\/h2>\n

All Raveon data radio modems have a built in RSSI indicator to help determine the signal strength of a received radio modem signal. \u00a0Raveon GPS tracking products also include location (latitude\/Longitude) with the RSSI information which makes RF propagation\u00a0analysis very simple.<\/p>\n

RSSI is usually expressed in dBm which is decibels relative to milliwatts of received power. \u00a00dBm = 1 mW. \u00a0Every time \u00a0the \u00a0received power drops in half, the RSSI will change by 3dB. \u00a0.5mW = -3dBm. \u00a0 .25mW = -6dBm and so on. \u00a0Everytime the received power drops by 1\/10th, the RSSI will drop by 10dB. \u00a01\/10 of a mW is -10dBm. \u00a01\/100th of a mW is -20dBm, \u00a01\/1000th of a mW is -30dBm and so on.<\/p>\n

Radio Signal Strength (RSSI) will drop the further away a receiver is from the transmitter it is receiving. \u00a0This is a square-law phenemoena, so the received signal will drop by at least 1\/4 every time the distance from the transmitter doubles. \u00a01\/4power is a 6dB drop in RSSI, so when a receiver with a given RSSI moves twice the distance from a transmitter, the RSSI will drop at least 6dB. \u00a0For quick range calculations, assume 6-10dB drop for every doubling of distance.<\/p>\n

\"Radio<\/p>\n

For example, in the above image, if the center dark-blue circle were 1\/2 mile across at -70dBm signal, the -80dBm range would be about 1 mile, the -90dBm circle 2 miles and the -100dBm circle 4 miles across.<\/p>\n

But, remember that most all communication systems on earth are limited by terrain not line-of-sight distance. \u00a0A 5 watt radio modem transmitting 5 watts of RF can\u00a0be received thousands of miles away in free-space. \u00a0On earth, it may only be 1 to 100 miles. \u00a0Terrain, antenna heights, foliage, buildings, interference, and antenna gains play a huge role in determining how far a radio can communicate. \u00a0Also due to multipath, moving objects, and varying antenna positions, the RSSI at a typical location in the fringe area of reception will often vary 10dB – 20dB over a short amount of time (seconds). \u00a0This may cause sporadic reception, but with a good communication protocol, the 20dB drop-outs will not be noticed.<\/p>\n

Signal strengths near a base station \u00a0are typically in the -30 to -60dBm range. \u00a0Most Raveon radios can measure an RSSI as large as -60dBm. \u00a0Above that, they will report some maximum value such as -58. \u00a0The upper limit varies by model. \u00a0Here is a rough summary of RSSI signal implications.<\/p>\n

 <\/p>\n\n\n\n\n\n\n\n\n
\n

\u00a0RSSI Level<\/span><\/strong><\/h3>\n<\/td>\n

\n

\u00a0Comments<\/span><\/strong><\/h3>\n<\/td>\n<\/tr>\n

\u00a0\u00a0-30 to -60\u00a0<\/strong><\/td>\n\n

\u00a0Very strong. \u00a0The receiver is very near the transmitter or base station.<\/p>\n<\/td>\n<\/tr>\n

\u00a0-60 to -90<\/td>\n\u00a0 Excellent signal strength. \u00a0Usually the close to 100% coverage and reception.<\/td>\n<\/tr>\n
\u00a0-90 to -105<\/td>\n\u00a0Good reception, but occasional missed data.<\/td>\n<\/tr>\n
\u00a0-105 to -115<\/td>\n\u00a0\u00a0Reception can be 100% but often will have drop-outs\/blind spots when the average signal is this weak.<\/td>\n<\/tr>\n
\u00a0-105 to -120<\/td>\n\u00a0Signal reception will be sporadic. \u00a0Don’t design a reliable system to work with this weak of a signal unless you utilize an error-correcting and lost-message protocol.<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n

 <\/p>\n

 <\/p>\n

 <\/p>\n

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

Radio Signal Strength Indication (RSSI) All Raveon data radio modems have a built in RSSI indicator to help determine the signal strength of a received radio modem signal. \u00a0Raveon GPS tracking products also include location (latitude\/Longitude) with the RSSI information which makes RF propagation\u00a0analysis very simple. RSSI is usually expressed in dBm which is decibels […]<\/p>\n","protected":false},"author":1,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":[],"categories":[4],"tags":[],"_links":{"self":[{"href":"https:\/\/www.raveon.com\/data_radio_info\/wp-json\/wp\/v2\/posts\/1021"}],"collection":[{"href":"https:\/\/www.raveon.com\/data_radio_info\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.raveon.com\/data_radio_info\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.raveon.com\/data_radio_info\/wp-json\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.raveon.com\/data_radio_info\/wp-json\/wp\/v2\/comments?post=1021"}],"version-history":[{"count":6,"href":"https:\/\/www.raveon.com\/data_radio_info\/wp-json\/wp\/v2\/posts\/1021\/revisions"}],"predecessor-version":[{"id":1028,"href":"https:\/\/www.raveon.com\/data_radio_info\/wp-json\/wp\/v2\/posts\/1021\/revisions\/1028"}],"wp:attachment":[{"href":"https:\/\/www.raveon.com\/data_radio_info\/wp-json\/wp\/v2\/media?parent=1021"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.raveon.com\/data_radio_info\/wp-json\/wp\/v2\/categories?post=1021"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.raveon.com\/data_radio_info\/wp-json\/wp\/v2\/tags?post=1021"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}