In this article, an RFI detector is proposed which is based on a spectral
profile comparison. Real time detection is provided by taking advantage of
the existing computational capability of correlators. For example, monochromatic
RFI having an 
are detected. This requires only Q=30
time-lags of the correlation function estimated over N=10000 samples.
This study was made in the framework of the coarse quantized correlators, which are in current use in the radio astronomy community. However, the proposed application can be extended to any type of correlators. To limit the impact of the RFI spectral appearance, a multi-resolution strategy is proposed. A later version of this detector could adopt a multi-scale strategy with the aim of minimizing the receiver blanking according to RFI duration.
Figure 8: Images of the spread spectrum RFI generator: a)
The code generator
which delivers two pseudo-random codes similar to those generated by
the GLONASS or
GPS system, b) The quadriphase modulator using the two
pseudo-random codes,
c) the helical antennas which are fixed on the spherical
mirror of the
NRT and emit the RFI signal coming from the modulator
Acknowledgements
The authors gratefully acknowledge C. Fabrice and L. Denis for their assistance in performing the tests with experimental data. The Nançay Radio Observatory is the Unité Scientifique Nançay of the Observatoire de Paris, associated as Unité de Service et de Recherche (USR) No. B704 to the French Centre National de Recherche Scientifique (CNRS). The Nançay Observatory also gratefully acknowledges the financial support of the Conseil Régional of the Région Centre in France.