Added rtl_sdr_strength.py

diff --git a/scripts/rtl_sdr_strength.py b/scripts/rtl_sdr_strength.py
new file mode 100755 (executable)
index 0000000..5e09c52
--- /dev/null
+++ b/scripts/rtl_sdr_strength.py
@@ -0,0 +1,27 @@
+#!/usr/bin/env python
+# -*- coding: iso-8859-15 -*-
+
+import sys
+import subprocess
+import re
+import rospy
+import tf
+import tf2_ros
+from time import sleep
+
+rospy.init_node('wifi_strength')
+
+tfBuffer = tf2_ros.Buffer()
+listener = tf2_ros.TransformListener(tfBuffer)
+regex_lq = re.compile("Link Quality=(\d*)/(\d*)")
+while not rospy.is_shutdown():
+       popen = subprocess.Popen("rtl_power -f 868.3M:868.4M:10k -g 42 -i 1".split(), stdout=subprocess.PIPE)
+       while True:
+               line = popen.stdout.readline()
+               if line == "":
+                       break
+               power = line.replace("\n", "").split(",")[6:]
+               power = [float(s) for s in power]
+               pos = tfBuffer.lookup_transform("map", 'base_link', rospy.Time(0), rospy.Duration(1.0))
+               print '{"x":%.2f, "y":%.2f, "power": %s},' % (pos.transform.translation.x, pos.transform.translation.y, power)
+               sys.stdout.flush()