Meaning
Performance measurement identifies the reduction in receiver sensitivity caused by internal electromagnetic noise within a wireless device. Total isotropic sensitivity measures the ability of a radio to hear weak signals from all directions. When tis desensitization occurs, the effective range of the device is reduced because the internal noise floor has risen.
This problem is common in dense electronic assemblies where many components operate at high frequencies.
Noise Source
Internal circuits generate radiation that couples into the antenna. Digital clocks and switching power supplies are common causes of tis desensitization in small devices. If these signals land on the same frequency as the receiver, the radio cannot distinguish the signal from the noise.
Receiver Sensitivity
Radiated power from the transmitter can also leak back into the receiving path. Measuring tis desensitization involves placing the device in an anechoic chamber and comparing the sensitivity with the transmitter on and off. A large difference indicates that the receiver is being blinded by its own radio.
Mitigation Path
Engineering solutions focus on isolating the antenna from the noise sources. Shields and filters are used to block the interference that leads to tis desensitization in the circuit. Better grounding reduces the noise currents on the board.
In some cases, the layout must be changed to move sensitive components away from the noise. These improvements are verified through repeated testing in the chamber to ensure the device meets the performance requirements for the network.
