RSSI Notes

RSSI = Received Signal Strength Indicator

RSSI is a measurement of the strength of a radio signal that a receiver receives. It's a crucial metric in wireless communication systems, including Motorola MOTOTRBO two-way radios. This is a value usually represented in dBm (or decibles-miliwatts). I've noticed Motorola likes to use dBm for their subscriber units and repeaters.

dB (decibel) and dBm (decibel-milliwatt) are both units used to measure signal strength or power, but they have different reference points.

• dB: This is a dimensionless unit that represents a ratio of two quantities. It's used to express the relative difference between two power levels. For example, a 10 dB increase in power means the signal is 10 times more powerful
•  dBm: This is a unit of absolute power. It represents the power level relative to 1 milliwatt (mW). So, 0 dBm means a power level of 1 mW. A 10 dBm increase means the power level is 10 times more powerful than 1 mW

    dB is used to compare two power levels.  dBm is used to express an absolute power level.

To convert between dB and dBm:

•  If you have a value in dBm, you can convert it to dB by subtracting 30
• If you have a value in dB, you can convert it to dBm by adding 30

For example:

• 30 dBm is equivalent to 0 dB
• 0 dB is equivalent to 30 dBm

General Value Ranges

This table below shows my preferences with radio's RSSI. Each value range will vary greatly not only by manufacturer, application, terrain, etc. but your own preferences may alter this. Some people say -60 to -90 is Excellent. Ok, no problem!