Using the QIMD Calculator

The Q-factor influenced Intermodulation Distortion (QIMD) Calculator screens a repeater channel plan for likely intermodulation products. Use it to find frequency coincidences that deserve engineering review, not to certify a site as free of interference.

Enter the channel plan

Add one row for each channel and enter the receive frequency, optional IF, receive bandwidth, transmit frequency, and transmit bandwidth as applicable. Choose the channel bandwidth for new rows or apply a bandwidth to all rows. Use the import controls for supported CSV or Excel plans, and check the imported values before calculating.

Choose screening assumptions

Set the hit tolerance to control how close a calculated product must be to a receive frequency to be listed. Choose an analysis mode: LMR screening checks common odd orders, Advanced explores orders 2–9, Exhaustive checks signed pairwise combinations, and Custom range lets you define a range. Select product-width and receiver-profile options to match the screening question; the superhet profile uses the IF column.

Calculate and review

Click Calculate. Review each reported product, affected receiver, order, and frequency difference against your selected tolerance. A hit is a screening finding to assess; it is not a signal-level prediction. Export the configuration or results in a supported format for review.

Limits: This analysis cannot represent the full RF environment, equipment response, antenna coupling, or measured signal levels. A clean calculation is not a desense clearance. Confirm critical plans with Telewave engineering and on-site measurements.