In the mid 1970's the British Post Office, (now British Telecom International) decided that there was a need to develop a new antenna control algorithm to overcome the weaknesses of ‘steptrack’ algorithms. These weaknesses tended to result in mis-pointing of the antenna and loss of track when operating with scintillating or fading satellite beacons, high inclination orbit, and/or narrow 3-dB groundstation antenna beamwidths. There were alternatives, such as the ‘monopulse’ method, but these tended to be extremely expensive to implement.

BPO therefore funded a detailed study, by a team of experts that ultimately became part of the Advantech family, of the applicability of optimal filtering techniques to overcome these limitations. The study proposed a new tracking algorithm based on orbit modelling. Trials showed that its performance was on par with monopulse control, that it was fully compliant with Intelsat pointing specifications and that it overcame the problems associated with step track controllers. This algorithm was the first antenna control algorithm to use orbit modelling and became known as Smoothed Step Track (SST).

The SST algorithm was licensed to Signal Processors Ltd (SPL), on an exclusive basis, in 1983, with SPL becoming part of the Advantech group in 2001. Since than we have continued developing the algorithm, enhancing its capabilities and adding new features and interfaces. The result is the INTRAC enhanced orbit modelling algorithm (INTRAC is an acronym for INtelligent TRacking Antenna Controller).

A more detailed description of the INTRAC algorithm for tracking is presented in our white paper entitled ‘The INTRAC Algorithm’