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-rw-r--r--utilities/modem.py111
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diff --git a/utilities/modem.py b/utilities/modem.py
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+#!/usr/bin/env python
+
+import sys, wave
+
+#
+# "Modem" wav creator for "Next Gen" Tagsu Modem :)
+#
+# Author: Jari Tulilahti
+# Copyright: 2014 Rakettitiede Oy
+# License: LGPLv3, see COPYING and COPYING.LESSER -files for more info
+#
+# Usage:
+# python modem.py <input_filename> [output_wav_filename] [samplerate]
+#
+# Default sample rate is 48000
+# Default output to stdout if no wav filename given
+#
+# Working sample rates are between 16000 - 48000:
+#
+# 16000 (~4000 bps)
+# 22050 (~5500 bps)
+# 24000 (~6000 bps)
+# 32000 (~8000 bps)
+# 44100 (~11025 bps)
+# 48000 (~12000 bps)
+#
+# NOTICE:
+#
+# Actual speed depends of the data, as zeroes and ones take
+# different amount of samples, the more zeros, the faster the speed.
+# Average bps has been calculated using data "0101010101..."
+#
+
+class modem:
+
+ bits = [[3 * chr(0), 5 * chr(0)], [3 * chr(255), 5 * chr(255)]]
+ sync = [17 * chr(0), 17 * chr(255)]
+ hilo = 0
+
+ # Nothing here
+ def __init__(self):
+ pass
+
+ # Generate one sync-pulse
+ def syncsignal(self):
+ self.hilo ^= 1
+ return self.sync[self.hilo]
+
+ # Decode bits to modem signals
+ def modemcode(self, byte):
+ bleep = ""
+ for x in xrange(8):
+ self.hilo ^= 1
+ bleep += self.bits[self.hilo][byte & 0x01]
+ byte >>= 1
+ return bleep
+
+ # Return <length> samples of silence
+ def silence(self, length):
+ return chr(127) * length
+
+
+if len(sys.argv) < 2:
+ print """Usage: {0} <input_filename> [output_wav_filename] [samplerate]
+
+ input_filename Data file as input to modem.
+ output_wav_filename Write output-wav to this file. If empty, output to STDOUT.
+ samplerate Sample rate between 16000 - 48000. Default is 48000.
+ """.format(sys.argv[0])
+ sys.exit()
+
+sound = ""
+
+m = modem()
+cnt = 0
+
+# Add silence
+# sound += m.silence(24000)
+
+# Add 4 sync signals to start
+for x in xrange(4):
+ sound += m.syncsignal()
+
+# Send Actual data
+f = open(sys.argv[1])
+for byte in f.read():
+ sound += m.modemcode(ord(byte))
+
+ # Add counter
+ cnt += 1
+
+ # After every 10 bytes, send 2 sync signals
+ if cnt == 10:
+ for x in xrange(2):
+ sound += m.syncsignal()
+ cnt = 0
+
+# End transmission with few sync-signals
+for x in xrange(4):
+ sound += m.syncsignal()
+
+# Output the generated sound (no wav headers)
+if len(sys.argv) <= 2:
+ print sound
+else:
+ freq = int(sys.argv[3]) if len(sys.argv) > 3 else 48000
+ wav = wave.open(sys.argv[2], 'wb')
+ wav.setparams((1, 1, freq, 0, "NONE", None))
+ wav.writeframes(sound)
+ wav.close()
+