The Code

Snippet 1

#!/usr/bin/perl  -w
use strict;

my $ip = shift;
my $port = shift;
($ip && $port) || die "Usage: $0 ip port\n";

open(NC, "nc $ip $port |") || die "Couldn't spawn nc: $!\n";

while(<NC>) {
  if(/Signal level:-?(\d+).*Noise level:-?(\d+)/) {
    print "$1 $2\n";
    exit;
  }
}

die "Warning: couldn't find signal and noise!\n";

Snippet 2

/usr/local/rrdtool/bin/rrdtool create \
 /home/rob/radio/radio.rrd \
 --step 300 \
 DS:signal:GAUGE:600:0:150 \
 DS:noise:GAUGE:600:0:150 \
 RRA:AVERAGE:0.5:1:600 \
 RRA:AVERAGE:0.5:6:700 \
 RRA:AVERAGE:0.5:24:775 \
 RRA:AVERAGE:0.5:288:797 \
 RRA:MAX:0.5:1:600 \
 RRA:MAX:0.5:6:700 \
 RRA:MAX:0.5:24:775 \
 RRA:MAX:0.5:288:797

Snippet 3

/usr/local/rrdtool/bin/rrdtool graph - \
 --imgformat=PNG \
 --start="-604800" \
 --title=" Radio" \
 --rigid \
 --base=1000 \
 --height=120 \
 --width=500 \
 --upper-limit=105 \
 --lower-limit=60 \
 --vertical-label="dBm" \
 DEF:a="/home/rob/radio/ radio.rrd":signal:AVERAGE \
 DEF:b="/home/rob/radio/ radio.rrd":noise:AVERAGE \
 AREA:a#74C366:"Signal" \
 LINE1:b#FF0000:"Noise" \
 > graph.png