Intermodulation calculator for accurately assessing frequency problems
In locations where several transmitters and receivers are operating, signals will interact by what is referred to as the heterodyne effect; interaction (or intermodulation) products are produced on all sum/difference and product combination frequencies of every signal present. IMP Calc computes the intermodulation products.
Calculating intermodulation has always been a headache for engineers – numerous potential combinations of frequencies have to be cross-checked to identify whether they cause problems at the victims’ receivers. Even with only a handful of frequencies, the problem can expand beyond the capabilities of the average spreadsheet. This is twofold when signal bandwidths are also considered.
IMP Calc is a simple yet powerful utility which removes the headache of calculating all intermodulation products when checking transmitter interference and receiver susceptibility problems. The tool allows the user to edit frequency listings and add potential interferer-frequencies and receiver-frequencies where intermodulation protection is sought. Each element in the list may be given a name, channel spacing, protection bandwidth and frequency offsets, as well as having planned or commissioned status.
After intermodulation calculation is complete, a full or constrained result listing in the frequency band can be viewed for any combination of 3rd, 5th, 7th and 9th order components. This utility highlights the composition of intermodulation frequencies allowing the engineer to quickly identify problem frequencies. The outputs from IMP Calc can be saved to disk, printed or copied to other applications. The files are stored in comma separated ASCII format, allowing direct manipulation in spreadsheets such as Excel.