De-Confliction Filtering in Communication Systems

The dense signal environment in which radio communication systems work becomes even more challenging with the shift to higher capacity links needing wider bandwidth in which to operate. Signal spreading caused by intermodulation in the  transmitter and receiver requires either extremely linear devices or suitable filtering to avoid interference. The situation becomes most severe where countermeasures are deployed that risk, as a minimum, reducing system dynamic range.

One such environment is that experienced by tactical communication systems operating in the 200-450MHz frequency range. Radios operating in this band can generate harmonics, broadband noise and intermodulation distortion that could interfere with other systems at adjacent frequencies. Transmit filtering is used to mitigate these effects, but the number of possible channels and the passband width of each requires a tuneable filter to meet the flexibility required.