An Interference-Excising Correlator for Radio Astronomy

A correlating interferometer is described that operates in the HF communications band in the presence of levels of narrow-band radio interference that would normally make flux-density measurements impossible. Satisfactory operation of the correlator is achieved by using a microprocessor programmed to examine the FFT cross-power spectrum of the received signals in such a way as to permit the on-line identification, and the subsequent excision from the data, of interference appearing within the system bandwidth. Some experimental records are presented that illustrate the relative improvements possible with interference excising.