From e63ecbb75dafeb19de9a0eea8a6b228f0752ee37 Mon Sep 17 00:00:00 2001
From: Sebastian Muszytowski <sebastian@muszytowski.net>
Date: Thu, 14 Jan 2016 21:11:29 +0100
Subject: add tagsu-avr-modem from Rakettitiede Oy

---
 utilities/modem.py | 111 +++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 111 insertions(+)
 create mode 100644 utilities/modem.py

(limited to 'utilities')

diff --git a/utilities/modem.py b/utilities/modem.py
new file mode 100644
index 0000000..f2e2b1b
--- /dev/null
+++ b/utilities/modem.py
@@ -0,0 +1,111 @@
+#!/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()
+
-- 
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