Measured Signal Levels In Test Mode versus Handset Indicator Bars
There are several resources on the Internet with published instructions for setting handsets into Test Mode, so that a user may use the handset as a received signal strength meter. This mode is considerably more accurate than the 5 or so indicator bars that all handsets display for signal strength, as the 5 bars are used to depict a very large range of received signal power.
Signal strength for cellular handsets is measured in decibels referenced to one milliwatt or dBm. Typical cellular signal strength would measure anywhere from -55 to -60 dBm (excellent signal) to -110 dBm or lower (very poor signal), so the 5 indicator bars on a handset can represent a range of 50 to 60 dB in signal strength, or 10 to 12 dB per bar.
When developing an in-building system coverage plan, the external signal strength outside the building will help to design a system and adequately predict the system's performance inside the building. Using the bars of a handset to determine signal strength can provide a broad range of performance values, as opposed to the Test Mode signal level measurement, with a narrower range of error.
Issues With Setting Handsets in Test Mode
There are several resources on the Internet that publish the details for setting various phone models into Test Mode for received signal measurements. There are a few issues surrounding this that users should be aware of:
|Although generally accurate, some of the instructions provided may not always work with specific handsets. This may be a function of how the handsets are programmed by the manufacturers for a specific wireless service provider carrying those models, or slight differences in test software used by the manufacturer from one hanset version to the next.|
|Test Mode is not a generally supported operating mode for the handset and is not designed to withstand erroneous key entries while a user is setting the handset in Test Mode. In some cases a handset may be placed into a mode where the device does not function properly, and there is little in the way of published resources for resetting the handset to its regular functionality. Caution is required by the user when programming a handset for Test Mode.|
Safe Signal Level Measurements
We have not reproduced instructions for setting handsets into Test Mode, nor do we endorse or reject any sites that publish instructions for programming handsets for Test Mode. At this time, we have published instructions for the BlackBerry family of personal digital assistants (PDA), as they have an option for displaying actual received signal strength in dBm without the need to program the handset. We will publish instructions for other handsets where programming is not required to see received signal strength, as this information becomes available to us.
Select a handset manufacturer below for signal strength measurement instructions.
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