MULTI-FREQUENCY RADIO INTERFEROMETRY ALGORITHM

Анотація

This article is a continuation of the work
published in (Orlov, 2018). A method of multi-frequency
beamforming of a radio interferometer is proposed. The
model diagram is presented, which consists of two antenna
arrays, filters, receivers and a signal summing circuit. The
model works as follows. The signals received by the
antennas pass through the narrow-band filters of the
receiving devices, which are tuned to certain frequencies,
after which they are subjected to multiplicative processing
and weighted summation with their coefficients.
In this work, model the system of a radio
interferometer based on multi-frequency signal
processing, and study the possibilities of minimizing the
level of side lobes of the antenna pattern (AP). It is shown
that a decrease in the level of side lobes is possible due to
the expansion of the frequency range or the application of
signal processing from several clusters (antenna arrays),
due to their summation in the interferometer circuit. For
the case of three bases of the interferometer, consisting of
the same antenna arrays, the total AP is calculated. In this
case, a significant reduction of the side lobes to the level
of the side lobes of a single antenna array is achieved.
Further optimization of the radiation pattern can be
carried out by choosing the frequency ranges of the
interferometers and weights when summing the signals.
The proposed method makes it possible to adapt the
interferometer AP due to time processing in frequency
channels. The choice of the frequency grid and weighted
multi-frequency signal processing provide a decrease in
the level of side lobes and increase the resolution of the
instruments. The application of the proposed algorithms
will reduce the confusion effect from closely spaced radio
sources. The computational possibilities of weighted
processing are realized in real time, taking into account
the rotation of the Earth, scanning the AP and angular
arrangement of radio sources.