Propagation and interference measurements for use in real-time frequency management

Two systems for interference and propagation measurement have been developed and integrated to a point where they can form the basis of a frequency management scheme embedded within a digital HF terminal architecture. The interference measurements are based upon the use of template correlation which is a frequency domain analysis and optimisation process. The local interference spectrum is obtained using a FFT method. The other propagation measurement system evaluates the multi-path structure of the channel which influences the maximum transmission data rate which can be employed before inter-symbol interference becomes excessive. An optimum working frequency can be selected once maximum and lowest usable frequencies are identified. Data from the two sets of measurements are coalesced into a comprehensive figure-of-merit which is used for channel selection