Variables that affect the range of RF data systems
When designing an RF communication system, the following list of variables should be considered. These variables affect the system's range and can be manipulated to optimize system performance.Summary of Range Variables
| Range Variable | Range Reducers | Range Enhancers |
|---|---|---|
| Receiver Sensitivity | Poor Receiver Sensitivity (negative values are used to express receiver sensitivity, thus -110 dBm is better for range than -93 dBm) --> 6 dB halves the range in LOS (line-of-sight) outdoor environments --> 10 dB halves the range in urban/indoor environments |
Excellent Receiver Sensitivity --> 6 dB doubles the range in LOS (line-of-sight) outdoor environments --> 10 dB doubles the range in urban/indoor environments |
| Sensitivity is a measure of the minimum power level at which the receiver is able to detect the RF signal and demodulate the data. | ||
| Antenna Gain* | Low Transmit Power --> 6 dB halves the range in LOS (line-of-sight) outdoor environments --> 10 dB halves the range in urban/indoor environments |
High Transmit Power* --> 6 dB doubles the range in LOS (line-of-sight) outdoor environments --> 10 dB doubles the range in urban/indoor environments |
| Antenna Cable | Long Antenna Cable | Short Antenna Cable |
| Fresnel Zone (The environment between transceivers) | Physical Obstructions (walls, trees, buildings, etc.) | No Physical Obstructions between transmitter and receiver |
| Radio Frequency Interference | Interferences such as cell phones, microwave ovens, pagers, etc. | Interference-free environment |
| Data Rate | High Data Rate --> Doubling the data rate can reduce range by 29% |
Low Data Rate --> Halving the data rate can increase range by 29% |
| Frequency | High Frequency --> 2.4 GHz frequency systems will have approximately ½ the range of 900 MHz systems (all else held equal) |
Low Frequency --> 900 MHz frequency systems will have approximately 2x the range of 2.4 GHz systems (all else held equal) |
* The amount of energy that an RF device can radiate into the air is regulated by government agencies, thus Transmitter Power and Antenna Gain are limited in their abilities to increase range. Receiver Sensitivity is not regulated and thus presents a variable from which considerable competitive advantages can be lost or gained.
