Add Glonass CA ranging code generation module and unit test

Author: Pasi Miettinen

peregrine/include/glo_ca_code.py

@@ -0,0 +1,70 @@
+# -*- coding: utf-8 -*-
+#!/usr/bin/env python
+
+# Copyright (C) 2016 Swift Navigation Inc.
+#
+# Contact: Pasi Miettinen <pasi.miettinen@exafore.com>
+# This source is subject to the license found in the file 'LICENSE' which must
+# be be distributed together with this source. All other rights reserved.
+#
+# THIS CODE AND INFORMATION IS PROVIDED "AS IS" WITHOUT WARRANTY OF ANY KIND,
+# EITHER EXPRESSED OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE IMPLIED
+# WARRANTIES OF MERCHANTABILITY AND/OR FITNESS FOR A PARTICULAR PURPOSE.
+
+import types
+import sys
+import numpy as np
+
+
+def generate_glo_ca_code():
+  """
+  Function generates PRN sequence for Glonass.
+  All GLONASS satellites use the same C/A-code,
+  generated by a 9-bit shift register.
+  """
+  code = '111111111'
+  output = np.zeros(511, np.int8)
+  for i in xrange(len(output)):
+    if '0' == code[6]:
+      output[i] = 1
+    else:
+      output[i] = -1
+    if int(code[4]) ^ int(code[8]):
+      code = '1' + code[:8]
+    else:
+      code = '0' + code[:8]
+  return output
+
+
+def readonly(value):
+  return property(lambda self: value)
+
+
+class glo_ca_code(types.ModuleType):
+  """
+  Implement module level variable as readonly by imitating module with
+  this class.
+  """
+
+  value = readonly(generate_glo_ca_code())
+
+  def __dir__(self):
+    return ['__doc__', '__name__', 'value']
+
+tmp = glo_ca_code(__name__)
+tmp.__doc__ = """
+  PR ranging code is a sequence of maximum length of shift register with a
+  period 1 millisecond and bit rate 511 kbps. PR ranging code is sampled at
+  the output of 7th stage of the 9-stage shift register. The initialization
+  vector to generate this sequence is (111111111). The first character of the
+  PR ranging code is the first character in the group 111111100, and it is
+  repeated every 1 millisecond. The generating polynomial, which corresponds
+  to the 9-stage shift register is G(X) = 1 + X^5 + X^9
+
+  Function outputs the bitstream as str and time advances from left to right
+  output[0] ... output[510]
+  0ms ----------> 1ms
+
+  In the sequence '0' is represented as '1', 1 as -1
+  """
+sys.modules[__name__] = tmp

tests/test_glo_ca_code.py

@@ -0,0 +1,53 @@
+# -*- coding: utf-8 -*-
+
+# Copyright (C) 2016 Swift Navigation Inc.
+#
+# Contact: Pasi Miettinen <pasi.miettinen@exafore.com>
+# This source is subject to the license found in the file 'LICENSE' which must
+# be be distributed together with this source. All other rights reserved.
+#
+# THIS CODE AND INFORMATION IS PROVIDED "AS IS" WITHOUT WARRANTY OF ANY KIND,
+# EITHER EXPRESSED OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE IMPLIED
+# WARRANTIES OF MERCHANTABILITY AND/OR FITNESS FOR A PARTICULAR PURPOSE.
+
+from peregrine.include.glo_ca_code import value
+
+import numpy as np
+
+
+def test_glo_ca_code():
+
+  code = np.array(
+    [-1, -1, -1, -1, -1, -1, -1,  1,  1,  1,  1,  1, -1, -1, -1, -1,  1,
+     -1, -1, -1, -1, -1,  1,  1,  1, -1,  1, -1, -1, -1,  1,  1, -1, -1,
+      1,  1, -1,  1,  1,  1,  1,  1, -1,  1,  1, -1,  1, -1,  1,  1, -1,
+     -1, -1,  1, -1, -1,  1, -1,  1,  1,  1, -1, -1, -1, -1,  1,  1, -1,
+     -1, -1, -1, -1,  1,  1, -1, -1,  1, -1, -1,  1,  1,  1, -1,  1, -1,
+      1, -1,  1,  1, -1,  1,  1,  1, -1, -1, -1,  1,  1,  1, -1, -1,  1,
+     -1, -1,  1, -1,  1, -1,  1, -1, -1, -1,  1,  1,  1, -1,  1,  1, -1,
+     -1,  1,  1,  1, -1,  1,  1,  1, -1,  1,  1,  1,  1,  1,  1,  1,  1,
+     -1,  1,  1,  1,  1, -1,  1,  1,  1, -1, -1,  1,  1,  1,  1, -1,  1,
+      1, -1, -1, -1,  1,  1, -1,  1, -1,  1, -1,  1, -1, -1,  1,  1,  1,
+      1, -1, -1,  1, -1, -1, -1, -1,  1, -1,  1,  1, -1, -1,  1, -1, -1,
+     -1,  1,  1, -1,  1,  1,  1, -1,  1, -1,  1,  1,  1,  1, -1,  1, -1,
+      1, -1, -1,  1, -1,  1,  1, -1, -1, -1, -1, -1, -1,  1, -1, -1,  1,
+      1, -1,  1,  1, -1,  1,  1, -1,  1, -1, -1,  1, -1, -1, -1, -1, -1,
+     -1,  1,  1, -1,  1,  1, -1, -1,  1, -1,  1, -1,  1,  1, -1, -1,  1,
+      1, -1, -1,  1,  1,  1,  1,  1,  1,  1, -1, -1,  1,  1,  1, -1, -1,
+      1,  1, -1,  1, -1,  1,  1,  1, -1, -1,  1, -1,  1,  1, -1,  1, -1,
+     -1, -1, -1, -1, -1, -1,  1, -1,  1,  1,  1, -1,  1, -1, -1,  1,  1,
+      1, -1, -1, -1,  1, -1,  1, -1, -1,  1,  1, -1,  1, -1, -1,  1,  1,
+     -1, -1, -1, -1,  1,  1,  1, -1, -1, -1, -1, -1,  1, -1, -1, -1,  1,
+     -1,  1,  1,  1,  1,  1, -1, -1,  1, -1,  1, -1, -1,  1, -1, -1,  1,
+     -1, -1, -1,  1, -1, -1,  1,  1,  1,  1,  1, -1,  1, -1, -1,  1, -1,
+      1, -1, -1, -1, -1, -1,  1, -1,  1, -1,  1, -1,  1, -1,  1,  1,  1,
+      1,  1,  1, -1,  1, -1,  1,  1, -1,  1, -1,  1, -1, -1, -1, -1,  1,
+      1, -1,  1, -1, -1, -1,  1, -1, -1, -1,  1,  1,  1,  1,  1,  1, -1,
+     -1, -1,  1,  1, -1, -1, -1,  1, -1,  1,  1, -1,  1,  1, -1, -1, -1,
+     -1,  1, -1,  1, -1, -1, -1,  1, -1,  1, -1,  1,  1,  1, -1,  1,  1,
+     -1,  1,  1,  1,  1, -1, -1,  1,  1, -1, -1, -1,  1,  1,  1,  1, -1,
+      1, -1, -1, -1, -1,  1, -1, -1,  1, -1, -1,  1,  1, -1, -1,  1, -1,
+      1,  1,  1,  1, -1, -1, -1,  1, -1, -1, -1, -1,  1,  1,  1,  1, -1,
+     -1], dtype=np.int8)
+
+  assert((code == value).all())