Receive Signal Strength Indicator (RSSI) and EC/IO

Roger K. Parker Page 1

541-685-9045 x227

Received Signal Strength Indicator (RSSI) The current Received Signal Strength Indicator (RSSI) of the modem is indicated by a negative dBm value. This value relates to the signal strength of the cellular signal from the tower to the modem. The higher the number, the better the signal. The exact numbers vary between cellular carriers. However, -40 dBm to -70 dBm usually equates to the modem being in an excellent coverage area. The closer to –0 dBm, the stronger the signal. There is a point at which trying to obtain more signal delivers diminishing returns. Throwing gobs of money and time trying to get a –75 dBm signal down to –65 dBM will not gain you that much. This is especially true if your EC/IO is high. A Low RSSI and High EC/IO is bad, but a low RSSI and Low EC/IO is great. This table indicates the quality of the coverage area.

Coverage Area Quality RSSI (dBm) Excellent -10 to -70 Good -71 to -80 Fair -81 to -85 Weak -86 to -95 Very Weak -96 to -110 Negligible -111 and lower No Signal -125 or -65535 or 0

EC/IO The EC/IO is a measure of the quality/cleanliness of the signal from the tower to the modem and indicates the signal-to-noise ratio (the ratio of the received/good energy to the interference/bad energy). It is measured in decibels (dB). In a perfect world, where there is no true interference, the interference level is equal to the noise level resulting in an EC/IO = 0 dB. Once the EC/IO is above -5.0 dB, your connection is going to suffer. There are several factors that can contribute to a higher EC/IO value, including florescent lighting, electric motors, equipment, power supplies, bad/poor cabling, trees, hills, buildings, walls, shorted connectors, inaccurate antenna alignment, wrong antenna polarization, congestion at the tower, etc.

EC/IO (dB) Ranking

0 to -1.5 Excellent -1.5 to -5.9 Good -6.0 to -9.0 Marginal -9.0 + Poor/Unacceptable Notes: These values are usually a snapshot and will fluctuate with every update/refresh. When trying to activate a modem, the RSSI and EC/IO need to be in the “green” or sometimes will initiate when in the “yellow”, depending on the circumstances.

Receive Signal Strength Indicator (RSSI) and EC/IO

Roger K. Parker Page 2

541-685-9045 x227

From: Support <support@feeneywireless.com> To: "David S. Croker" <croker@usgs.gov>, Support <support@feeneywireless.com>, "Mark E. Meremonte" <meremonte@usgs.gov> Cc: "jkrueger@usgs.gov" <jkrueger@usgs.gov> Date: 03/20/2012 23:31 Subject: RE: ECIO and firmware questions [USGS]

Dave, The RSSI and EC/IO cheat sheet should help answer the first question. These are very important as the provide a measurement of the signal received by the modem from the tower. Signal strength (RSSI) and interference (EC/IO) help to diagnose issues with the modems. But there are other fields available that equally important (e.g. Network State – defining the state of the modem and Network service type – defining the service the modem is connecting (1xRTT, EV-DO Rev. 0 and EV-DO Rev. A). These are important to how the modem will perform and to aid in diagnosing issues with the device. When the modem is connecting with a 1X connection, it is performing essentially at dialup speeds and is 10 times slower than an EV-DO Rev. A connection. If you see a 1X, EV-DO Rev. A value for the service type, the modem is connected with EV-DO Rev. A, but will fail-over to a 1X connection if EV-DO is not available. The firmware for the Raven X has a definite impact on performance. The current firmware is 4.0.10.001 and can be found in the Info group, under the ALEOS Software Version field. There is a sequence of updates that must be performed. Another important item is the Preferred Roaming List (PRL). This is the list of towers available to the home network and should be kept up-to-date. To update the PRL for Sprint modems requires that you know what the Master Subsidiary Lock (MSL) for the modem. For Verizon, this is updated OTA. For Sprint the current PRL is 60783. I don’t recommend users perform the initial updates, as you need the firmware releases for the carrier (e.g. Sprint), modem model (e.g. Raven X), and hardware release (e.g. MC5725 or MC5728). After which keeping it up to date is much easier. Also the PRL must be provided by the carrier and is updated regularly. This is something we get notification of. Hope this helps. Thanks, Roger K. Parker

Engineering Technician rparker@feeneywireless.com

Feeney Wireless, LLC - 4085 W. 11th Ave. Unit #3, Eugene, Oregon 97402 (Free) 800-683-4818 (P) 541-685-9045 x227 (F) 541-284-0030 www.feeneywireless.com