There was a download of SIFMPRO 1.3.0.4 on the developer's website when we last checked. We cannot confirm if there is a free download of this software available. The actual developer of the free software is Sennheiser/SDA.
We cannot guarantee that the program is safe to download as it will be downloaded from the developer's website. Before launching the program, check it with any free antivirus software. The software lies within Office Tools, more precisely Calculators.
From the developer:
SIFM is the Sennheiser Software for rapid calculation of intermodulation-free radio frequencies for wireless microphone systems.
Interference due to intermodulation generally occurs when at least two transmitters close to the receiving antenna produce very strong signals in the receiver. The two signals form intermodulation products at non-linearities, such as transistors or other semiconductors in the receiver (e.g. in the mixer).
You may want to check out more software, such as ProCalc, WinConverter or WorldCalc, which might be similar to SIFMPRO.