This script is derived from gpsd.php, and generates a plot...

...of satellite position and signal strength over time. May be useful
if you're trying to set up a static receiver in an urban canyon. May
also be useful as an example of how to toss together a quick analyzer.

1 files changed, 190 insertions, 0 deletions

diff --git a/contrib/skyview.php b/contrib/skyview.php
new file mode 100755
index 00000000..587c8556
--- /dev/null
+++ b/contrib/skyview.php
@@ -0,0 +1,190 @@
+#!/usr/local/bin/php
+<?php
+
+# Copyright (c) 2006 Chris Kuethe <chris.kuethe@gmail.com>
+#
+# Permission to use, copy, modify, and distribute this software for any
+# purpose with or without fee is hereby granted, provided that the above
+# copyright notice and this permission notice appear in all copies.
+#
+# THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
+# WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
+# MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
+# ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES
+# WHATSOEVER RESULTING FROM LOSS OF USE, DATA OR PROFITS, WHETHER IN AN
+# ACTION OF CONTRACT, NEGLIGENCE OR OTHER TORTIOUS ACTION, ARISING OUT OF
+# OR IN CONNECTION WITH THE USE OR PERFORMANCE OF THIS SOFTWARE.
+
+if ($argc != 3){
+	die("usage: ${argv[0]} logfile imagefile\n");
+}
+
+$sz = 640;
+$radius = 8;
+$filled = 0;
+
+$im = imageCreate($sz, $sz);
+$C = colorsetup($im);
+skyview($im, $sz, $C);
+legend($im, $sz, $C);
+
+$lines = file($argv[1]);
+foreach ($lines as $line_num => $line) {
+	if (preg_match('/,Y=\S+ [0-9\.]+ (\d+):/', $line, $m)){
+		$n = $m[1];	
+		$s = explode(':', $line);
+		for($i = 1; $i <= $n; $i++){
+			$e = explode(' ', $s[$i]);
+			splot($im, $sz, $C, $radius, $filled, $e);
+		}
+	}
+}
+
+skygrid($im, $sz, $C);	# redraw grid over satellites
+imagePNG($im, $argv[2]);
+imageDestroy($im);
+
+exit(0);
+
+###########################################################################
+function colorsetup($im){
+	$C['white']	= imageColorAllocate($im, 255, 255, 255);
+	$C['ltgray']	= imageColorAllocate($im, 191, 191, 191);
+	$C['mdgray']	= imageColorAllocate($im, 127, 127, 127);
+	$C['dkgray']	= imageColorAllocate($im, 63, 63, 63);
+	$C['black']	= imageColorAllocate($im, 0, 0, 0);
+	$C['red']	= imageColorAllocate($im, 255, 0, 0);
+	$C['brightgreen'] = imageColorAllocate($im, 0, 255, 0);
+	$C['darkgreen']	= imageColorAllocate($im, 0, 192, 0);
+	$C['blue']	= imageColorAllocate($im, 0, 0, 255);
+	$C['cyan']	= imageColorAllocate($im, 0, 255, 255);
+	$C['magenta']	= imageColorAllocate($im, 255, 0, 255);
+	$C['yellow']	= imageColorAllocate($im, 255, 255, 0);
+	$C['orange']	= imageColorAllocate($im, 255, 128, 0);
+
+	return $C;
+}
+
+function legend($im, $sz, $C){
+	$r = 30;
+	$fn = 5;
+	$x = $sz - (4*$r+7) - 2;
+	$y = $sz - $r - 3;
+
+	imageFilledRectangle($im, $x, $y, $x + 4*$r + 7, $y + $r +1, $C['dkgray']);
+	imageRectangle($im, $x+0*$r+1, $y+1, $x + 1*$r + 0, $y + $r, $C['red']);
+	imageRectangle($im, $x+1*$r+2, $y+1, $x + 2*$r + 2, $y + $r, $C['yellow']);
+	imageRectangle($im, $x+2*$r+4, $y+1, $x + 3*$r + 4, $y + $r, $C['darkgreen']);
+	imageRectangle($im, $x+4*$r+6, $y+1, $x + 3*$r + 6, $y + $r, $C['brightgreen']);
+	imageString($im, $fn, $x+3+0*$r, $y+$r/3, "<30", $C['red']);
+	imageString($im, $fn, $x+5+1*$r, $y+$r/3, "30+", $C['yellow']);
+	imageString($im, $fn, $x+7+2*$r, $y+$r/3, "35+", $C['darkgreen']);
+	imageString($im, $fn, $x+9+3*$r, $y+$r/3, "40+", $C['brightgreen']);
+}
+
+function radial($angle, $sz){
+	#turn into radians
+	$angle = deg2rad($angle);
+
+	# determine length of radius
+	$r = $sz * 0.5 * 0.95;
+
+	# and convert length/azimuth to cartesian
+	$x0 = sprintf("%d", (($sz * 0.5) - ($r * cos($angle))));
+	$y0 = sprintf("%d", (($sz * 0.5) - ($r * sin($angle))));
+	$x1 = sprintf("%d", (($sz * 0.5) + ($r * cos($angle))));
+	$y1 = sprintf("%d", (($sz * 0.5) + ($r * sin($angle))));
+
+	return array($x0, $y0, $x1, $y1);
+}
+
+function azel2xy($az, $el, $sz){
+	#rotate coords... 90deg W = 180deg trig
+	$az += 270;
+
+	#turn into radians
+	$az = deg2rad($az);
+
+	# determine length of radius
+	$r = $sz * 0.5 * 0.95;
+	$r -= ($r * ($el/90));
+
+	# and convert length/azimuth to cartesian
+	$x = sprintf("%d", (($sz * 0.5) + ($r * cos($az))));
+	$y = sprintf("%d", (($sz * 0.5) + ($r * sin($az))));
+	$x = $sz - $x;
+
+	return array($x, $y);
+}
+
+function splot($im, $sz, $C, $r, $filled, $e){
+	list($sv, $az, $el, $snr, $u) = $e;
+
+	if ((0 == $sv) || (0 == $az + $el + $snr))
+		return;
+
+	$color = $C['brightgreen'];
+	if ($snr < 40)
+		$color = $C['darkgreen'];
+	if ($snr < 35)
+		$color = $C['yellow'];
+	if ($snr < 30)
+		$color = $C['red'];
+	if ($snr == 0)
+		$color = $C['black'];
+
+	list($x, $y) = azel2xy($el, $az, $sz);
+
+	if ($snr > 0){
+		if ($filled)
+			imageFilledArc($im, $x, $y, $r, $r, 0, 360, $color, 0);
+		else
+			imageArc($im, $x, $y, $r, $r, 0, 360, $color);
+	}
+}
+
+function elevation($im, $sz, $C, $a){
+	$b = 90 - $a;
+	$a = $sz * 0.95 * ($a/180);
+	imageArc($im, $sz/2, $sz/2, $a*2, $a*2, 0, 360, $C['ltgray']);
+	$x = $sz/2 - 16;
+	$y = $sz/2 - $a;
+	imageString($im, 2, $x, $y, $b, $C['ltgray']);
+}
+
+function skyview($im, $sz, $C){
+	$a = 90; $a = $sz * 0.95 * ($a/180);
+	imageFilledArc($im, $sz/2, $sz/2, $a*2, $a*2, 0, 360, $C['mdgray'], 0);
+	imageArc($im, $sz/2, $sz/2, $a*2, $a*2, 0, 360, $C['black']);
+	$x = $sz/2 - 16; $y = $sz/2 - $a;
+	imageString($im, 2, $x, $y, "0", $C['ltgray']);
+
+	$a = 85; $a = $sz * 0.95 * ($a/180);
+	imageFilledArc($im, $sz/2, $sz/2, $a*2, $a*2, 0, 360, $C['white'], 0);
+	imageArc($im, $sz/2, $sz/2, $a*2, $a*2, 0, 360, $C['ltgray']);
+	imageString($im, 1, $sz/2 - 6, $sz+$a, '5', $C['black']);
+	$x = $sz/2 - 16; $y = $sz/2 - $a;
+	imageString($im, 2, $x, $y, "5", $C['ltgray']);
+
+	skygrid($im, $sz, $C);
+	$x = $sz/2 - 16; $y = $sz/2 - 8;
+	/* imageString($im, 2, $x, $y, "90", $C['ltgray']); */
+
+	imageString($im, 4, $sz/2 + 4, 2        , 'N', $C['black']);
+	imageString($im, 4, $sz/2 + 4, $sz - 16 , 'S', $C['black']);
+	imageString($im, 4, 4        , $sz/2 + 4, 'E', $C['black']);
+	imageString($im, 4, $sz - 10 , $sz/2 + 4, 'W', $C['black']);
+
+}
+
+function skygrid($im, $sz, $C){
+	for($i = 0; $i < 180; $i += 15){
+		list($x0, $y0, $x1, $y1) = radial($i, $sz);
+		imageLine($im, $x0, $y0, $x1, $y1, $C['ltgray']);
+	}
+
+	for($i = 15; $i < 90; $i += 15)
+		elevation($im, $sz, $C, $i);
+}
+
+?>