Citation
Abstract
Antennas separated by long distances have large delays and delay rates among them. If wide-bandwidth signals are received, frequency domain beamformers based on filter banks can be used to carry out signal combination. A new scheme based on subband delay compensation is proposed in this article. The main advantages of this scheme are the wider field of view of the array, the reduction of distortion in the transfer function, and the simplification of communications among sites. In order to perform coherent combination, the delay and delay rates need to be estimated. In order to do so, an algorithm is devised to estimate the differential phase, delay, and delay rate between two antennas based on the subband signals. This algorithm is first developed for a stationary case, in which the delay rate is zero. The product of subband signals is averaged and an inverse discrete Fourier transform (IDFT) is carried out to yield an estimate of the cross-correlation. For the nonstationary case, first the delay rate is calculated by means of a two-dimensional IDFT, and from that point a function similar to the one in the stationary case is obtained so as to compute the delay and phase offset.
Details
- Volume
- 42-194
- Published
- August 15, 2013
- Pages
- 1–18
- File Size
- 704.2 KB