Chapter 6. RF Power Meter – Hardware
In this chapter, we will be building an RF power meter capable of measuring power levels from approximately +3 dBm to -60 dBm.
For those of you who are not familiar with RF terminology:
- 0 dBm is equivalent to 1 mW or 1/1000 of a watt
- A power level of -30 dBm is equivalent to 1 microwatt or 1/1000,000 of a watt
- A power level of -60 dBm is equivalent to 0.001 microwatts
Basically, the meter is capable of reading extremely low power levels, but requires an external attenuator to measure high power levels. The pros and cons of this feature will become clearer as we go on.
The heart of this project is Linear Technology's LTC5582 RMS RF power detector, as shown in the following image:
Linear Technology power detector
The actual interface to the BeagleBone is quite simple. Power is supplied by the BeagleBone and one of the analog inputs is used to measure the output from the detector. The output voltage swing from the detector is approximately...
