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/* CWirc - X-Chat plugin for sending and receiving raw morse code over IRC
(c) Pierre-Philippe Coupard - 18/06/2003
Simulated propagation / signal strength evaluation routines
This program is distributed under the terms of the GNU General Public License
See the COPYING file for details
*/
#include <stdlib.h>
#include "propagation.h"
/* Definitions */
#define HALF_SIGNAL_DROP_DISTANCE 200 /* km */
#define SPORADICE_UPDATE_PERIOD 500 /* ms */
/* Make up a signal strength (0 -> 100) from the distance in Km between sender
and receiver. The current simulation doesn't correspond to anything real but
allows us to not really exclude anybody anywhere in the world from being
received. */
double cwirc_determine_signal_strength(int distance)
{
return(1/(1+((double)distance/HALF_SIGNAL_DROP_DISTANCE)));
}
/* Simulate sporadic-E. Here, we do it solely by attenuating the signal at
random */
void cwirc_simulate_sporadicE(double *signal_strength,double ticklen)
{
static double rnd_update_timeout=0;
static double dir=1;
static double attn=1;
if(rnd_update_timeout<=0)
{
dir=rand()>RAND_MAX/2?ticklen/300:0;
rnd_update_timeout=SPORADICE_UPDATE_PERIOD;
}
rnd_update_timeout-=ticklen;
attn=(attn+dir)/(1+ticklen/300);
if(*signal_strength<0.2)
*signal_strength*=attn;
}
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