Meaning
Signal degradation occurs when a local noise source reduces the effective sensitivity of a receiver. This carrier desensitization often results from electromagnetic interference generated by internal clocks or power circuits within the same enclosure as the radio. The phenomenon defines the limit of usable range by raising the noise floor above the minimum discernible signal level.
Noise Contribution
Unwanted harmonics from high speed data lines couple into the antenna path. Local oscillators or processor buses create broadband noise that masks weak incoming signals. If the receiver front end saturates because of a strong nearby transmitter, the gain decreases and effective sensitivity drops.
Low noise amplifiers often fail to distinguish between the intended carrier and this integrated interference.
Mitigation Strategy
Shielding enclosures block direct radiated paths between noisy components and the antenna. Careful frequency planning ensures that switching regulator frequencies do not land on sensitive channels. Layout designers use guard traces and grounded metal cans to isolate the radio section from digital logic.
Proper grounding prevents noise from traveling through the reference plane. Filters added to signal lines suppress unwanted emissions before they reach the air interface. Component placement remains the primary tool for distance based isolation.
Measurement Protocol
Testing involves injecting a known signal level and measuring the bit error rate while the system is under full load. Engineers compare the sensitivity with the CPU idle against the sensitivity during peak data processing. A shift in the receiver floor of even a few decibels identifies a failure in integration.
This verification occurs during the engineering validation phase to ensure the product meets range specifications.
