The power of ATDI’s software suite continues to grow with a new set of features addressing interference caused by intermodulation.
Now available in ICS telecom and HTZ warfare, the new functionality helps prevent intermodulation (IM) interference in mobile systems. The feature was developed and tested to identify where train mobiles suffered intermodulation on a GSM-R system. The unwanted intermodulation phenomenon comes from the non-linearity of the amplifier in the receiving chain and is generated when two or more signals are present in a non-linear circuit.
When asked about the nature of intermodulation interference, Nick Kirkman, technical director, said, “Two or more signals can add together in a non-linear environment. For example, if two signals are present (f1 & f2) the intermodulation frequencies 2f1 – f2 and 2f2 – f1 may appear in the receiver: these are intermodulation products. The receiver, listening to a channel whose frequency is f0, is interfered by intermodulation products when the following conditions are met: f0 = 2f1 – f2 or f0 = 2f2 – f1; the intermodulation signals strength is above a given threshold. For wideband (UMTS, LTE) signals, the signal bandwidth also needs to be taken into account. Since UMTS and LTE signals are wide bandwidth so the intermodulation product becomes wideband, given that a non-linearity generates IM products through combining the different spectral components of the corresponding signals.
The new features incorporated in ICS telecom and HTZ warfare include:
- Application across multi-technologies (GSM/UMTS/LTE)
- Adaptive thresholds
- User defined thresholds
- Intermodulation at 2 and 3 frequencies
- User defined triggers
- User defined interference distance
*Image courtesy of www.radio-electronics.com