host: Complete calculations for VSWR in Python utils + better sensors output.

host/utils/umtrx_query_sensors.py

@@ -1,30 +1,12 @@
 #!/usr/bin/env python
 # -*- coding: utf-8 -*-
 
-##########################
-###  VSWR calculations
-##########################
-
-# Implemented as described at:
-# http://www.markimicrowave.com/assets/data/return%20loss%20to%20vswr.pdf
-
-import math
-
-TM10_VSWR_cal=0.3
-
-def vswr_volts_to_db(VPF, VPR, calibration=0, coef=0.05):
-  return (VPF-VPR-calibration)/coef
-
-def db_to_vswr(db):
-  gamma = math.pow(10, -db/20.0)
-  return (1+gamma)/(1-gamma)
-
-
 ##########################
 ###  Query sensors
 ##########################
 
 from umtrx_property_tree import umtrx_property_tree
+from umtrx_vswr import umtrx_vswr
 
 s = umtrx_property_tree()
 s.connect()
@@ -33,10 +15,17 @@ sensors_path="/mboards/0/sensors"
 res = s.list_path_raw(sensors_path)
 sensors_list = res.get('result', [])
 
+print "Sensors:"
 for sensor in sensors_list:
-  print s.query_sensor_raw(sensors_path+"/"+sensor)
+  reply = s.query_sensor_raw(sensors_path+"/"+sensor)
+  if reply.has_key('result'):
+    res = reply['result']
+    print "  %15s = %9s %s" % (res['name'], res['value'], res['unit'])
+  else:
+    print "Can't read sensor %s" % sensor
 
 #vswr_calibration = TM10_VSWR_cal
+#vswr_calibration = TM3_VSWR_cal
 vswr_calibration = 0
 for num in [1, 2]:
   vpr_name = 'voltagePR'+str(num)
@@ -44,11 +33,17 @@ for num in [1, 2]:
   if vpr_name in sensors_list and vpf_name in sensors_list:
     vpr = float(s.query_sensor_value(sensors_path+'/'+vpr_name))
     vpf = float(s.query_sensor_value(sensors_path+'/'+vpf_name))
-    vswr_db = vswr_volts_to_db(vpf, vpr, vswr_calibration)
-    if vswr_db == 0.0:
-      vswr = float("inf")
-    else:
-      vswr = db_to_vswr(vswr_db)
-    print "Channel %d VSWR = %.2f = %.1f dB" % (num, vswr, vswr_db)
+    vswr = umtrx_vswr(vpf, vpr, vswr_calibration)
+    print "TRX %d power detector:" % num
+    print "              VPF =  %5.2f  V"   % vpf
+    print "               PF = %5.1f   dBm" % vswr.pf()
+    print "              VPR =  %5.2f  V"   % vpr
+    print "               PR = %5.1f   dBm" % vswr.pr()
+    print "             VSWR = %6.2f"       % vswr.vswr()
+    print "            Gamma =   %5.3f"     % vswr.gamma()
+    print "      Return Loss = %5.1f   dB"  % vswr.return_loss()
+    print "    Mismatch Loss =   %5.3f dB"  % vswr.mismatch_loss()
+    print "    Through power =  %5.2f  %%"  % (100.0*vswr.pf_rate())
+    print "  Reflected power =  %5.2f  %%"  % (100.0*vswr.pr_rate())
 
 s.close()

host/utils/umtrx_vswr.py

@@ -0,0 +1,68 @@
+#!/usr/bin/env python
+# -*- coding: utf-8 -*-
+
+##########################
+###  VSWR calculations
+##########################
+
+# Implemented as described at:
+# http://www.markimicrowave.com/assets/data/return%20loss%20to%20vswr.pdf
+
+import math
+
+# TODO: requires better calibration
+TM10_VSWR_cal=0.3/2
+
+class umtrx_vswr:
+  def __init__(self, VPF, VPR, calibration=0, coef=0.05):
+    self.vpf = VPF
+    self.vpr = VPR
+    self.calibration = calibration
+    self.coef = coef
+    self._gamma = self._calc_gamma()
+
+  def _calc_gamma(self):
+    ''' Internal function: calculate Gamma '''
+    return math.pow(10, -self.return_loss()/20.0)
+
+  def pf(self):
+    ''' Estimated through power, dBm '''
+    return (self.vpf-self.calibration)/self.coef
+
+  def pr(self):
+    ''' Estimated reflected power, dBm '''
+    return (self.vpr-self.calibration)/self.coef
+
+  def return_loss(self):
+    ''' Estimated return loss, dB '''
+    return self.pf()-self.pr()
+
+  def gamma(self):
+    ''' Estimated Gamma '''
+    return self._gamma
+
+  def vswr(self):
+    ''' Estimated VSWR '''
+    gamma = self._gamma
+    if gamma == 1.0:
+      return float("inf")
+    else:
+      return (1+gamma)/(1-gamma)
+
+  def mismatch_loss(self):
+    ''' Estimated mismatch loss, dB '''
+    gamma = self._gamma
+    if gamma == 1.0:
+      return float("-inf")
+    else:
+      return -10.0 * math.log(1.0-gamma*gamma, 10)
+
+  def pf_rate(self):
+    ''' Estimated reflected power rate, % '''
+    gamma = self._gamma
+    return 1.0 - gamma*gamma
+
+  def pr_rate(self):
+    ''' Estimated reflected power rate, % '''
+    gamma = self._gamma
+    return gamma*gamma