An intermodulation interference source locator (IMISL)

The design of an intermodulation interference source locator (IMISL) test set that was developed for shipboard use in detecting and locating the sources of intermodulation interference in the frequency range of 20-30 MHz is described. The IMISL uses a dual-conversion superheterodyne receiver with a coherent detector to achieve high instantaneous dynamic range with low spurious signals. The fundamental principles of operation, specifications, and basic RF design approach are presented. The discussion covers how the test set was designed to locate shipboard sources of intermodulation (IM) interference in the presence of high-power transmit signals in the frequency range of 2 MHz-15 MHz. Figures are presented showing electrical and mechanical design approaches, including a single-man-portable transit case containing the test set and all its accessories.<
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