Accession Number:

ADA275685

Title:

Effects of Ground Reflections on Frequency Modulated Signals

Descriptive Note:

Rept. for Jan-May 1992

Corporate Author:

ROME LAB HANSCOM AFB MA

Personal Author(s):

Report Date:

1992-06-01

Pagination or Media Count:

57.0

Abstract:

It is well known that ground reflections cause ambiguities in radar detection and tracking. A more serious problem is the interference that occurs when the phase difference between the direct signal and the ground reflected signal is small. This has been well studied in the context of the usual pulsed signals. There is little that can be done to entirely eliminate this problem. In this report the effect on frequency modulated signals of reflections from surfaces with different statistics is investigated. The ground reflection studied in this report is the coherent reflection. Four different kinds of rough surfaces normal, exponential, Rayleigh and skew-normal are considered. In each case an explicit expression for the received signal is obtained. Although the normal distribution is the most commonly used model, in applications the surfaces often have asymmetric characteristics. The three other distributions considered in this report are asymmetric. It is found that the received signals for normal and exponential surfaces have quite different amplitude characteristics. It is found that the Gaussian model may be a reasonable approximation for such asymmetric surfaces only when the Rayleigh roughness parameter is small.

Subject Categories:

  • Active and Passive Radar Detection and Equipment

Distribution Statement:

APPROVED FOR PUBLIC RELEASE