# Accession Number:

## AD0749686

# Title:

## A Fortran Computer Program to Calculate the Range of a Pulse Radar

# Descriptive Note:

## Final rept.

# Corporate Author:

## NAVAL RESEARCH LAB WASHINGTON DC

# Personal Author(s):

# Report Date:

## 1972-08-28

# Pagination or Media Count:

## 61.0

# Abstract:

A Fortran computer program to calculate radar maximum range, written for the NRL CDC-3800 computer but adaptable to any computer with a Fortran compiler, is described. The computation follows previously established principles, with the pattern-propagation factors set equal to one, so that the range calculated is for free space in the sense that earths surface effects are not taken into account. However, the effects of a standard atmosphere are included in the calculation. Reflection-interference effects can be separately described by using the calculated free-space range as an input to computer plotting programs. The program calculates the range for any specified probability of detection, false-alarm probability, and Swerling fluctuation case by using a slightly modified subroutine written by Fehlner and coworkers of the Johns Hopkins University Applied Physics Laboratory. Postdetection noncoherent integration is assumed. The system noise temperature is computed including effects of galactic, cosmic blackbody, solar, and tropospheric noise, and the tropospheric molecular absorption for oxygen and water vapor is calculated for a standard atmosphere. The effect of refraction on the ray path is included in the absorption calculation by ray tracing, assuming a negative-exponential refractivity-height profile. The range of validity of the noise temperature and absorption calculations is approximately 100 MHz to 100 GHz. The computation requires a few seconds with the CDC-3800 computer.

# Descriptors:

# Subject Categories:

- Computer Programming and Software
- Active and Passive Radar Detection and Equipment