[TowerTalk] Autek RF-1

[psoper@donedeal.encore.com (Pete Soper)]

Here it is in C and Perl:

--------------- C -----------------
/*

 Take Z, SWR from RF-1 as two command line args, output R and X

 Only accurate if:
 a) SWR is > 1.2 and < 6 (better if less than 4)
 b) ratio of R/X between .2 and 5

 To determine sign of X:

 a) add 5pf cap to load, if Z increases X is positive if decreases, neg.
 b) if Z increases with increased frequency, X is positive
    if Z decreases with increased frequency, X is negative

*/

#include <stdio.h>
#include <stdlib.h>
#include <math.h>

void main( int argc, char **argv )
{
    float z,s,r,x;

    if( argc != 3 ) {
        fprintf( stderr, "usage: imp Z SWR\n");
        exit(1);
    }

    sscanf( argv[1], "%f", &z );
    sscanf( argv[2], "%f", &s );

    r = ( ( 2500.0 + ( z * z ) ) * s ) / ( 50.0 * ( ( s * s ) + 1.0 ) );

    x = sqrtf( fabsf( ( z * z ) - ( r * r ) ) );

    fprintf( stdout, "%6.1f (+/-)%6.1f\n", r, x );
}
--------------- Perl -----------------
#!/usr/local/bin/perl

#
# Take Z, SWR from RF-1 as two command line args, output R and X
#
# Only accurate if:
# a) SWR is > 1.2 and < 6 (better if less than 4)
# b) ratio of R/X between .2 and 5
#
# To determine sign of X:
#
# a) add 5pf cap to load, if Z increases X is positive if decreases, neg.
# b) if Z increases with increased frequency, X is positive
#    if Z decreases with increased frequency, X is negative
#

if( @ARGV != 2 ) {
    printf("usage: imp.pl Z SWR\n");
    exit(1);
}

$z = $ARGV[0];
$s = $ARGV[1];
$r = ( ( 2500.0 + ( $z * $z ) ) * $s ) / ( 50.0 * ( ( $s * $s ) + 1.0 ) );

if( $z > $r ) {
    $x = sqrt( ( $z * $z ) - ( $r * $r ) );
} else {
    $x = sqrt( ( $r * $r ) - ( $z * $z ) );
}

printf( "%6.1f (+/-)%6.1f\n", $r, $x );
-----------------------------------------------

Regards,
Pete
KS4XG

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