diff --git a/wifimon.py b/wifimon.py
new file mode 100755
index 0000000..035e2ce
--- /dev/null
+++ b/wifimon.py
@@ -0,0 +1,256 @@
+#!/usr/bin/python
+import csv
+import os
+import string
+import struct
+import subprocess
+import sys
+
+TCPDUMP_MAGIC = 0xa1b2c3d4
+TCPDUMP_VERSION = (2, 4)
+LINKTYPE_IEEE802_11_RADIOTAP = 127
+
+RADIOTAP_FIELDS = [
+    ('mac_usecs', 'Q'),
+    ('flags', 'B'),
+    ('rate', 'B'),
+    ('channel', 'HH'),
+    ('fhss', 'BB'),
+    ('dbm_antsignal', 'b'),
+    ('dbm_antnoise', 'b'),
+    ('lock_quality', 'H'),
+    ('tx_attenuation', 'H'),
+    ('db_tx_attenuation', 'B'),
+    ('dbm_tx_power', 'b'),
+    ('antenna', 'B'),
+    ('db_antsignal', 'B'),
+    ('db_antnoise', 'B'),
+    ('rx_flags', 'H'),
+    ('tx_flags', 'H'),
+    ('rts_retries', 'B'),
+    ('data_retries', 'B'),
+    ('channelplus', 'II'),
+    ('ht', 'BBB'),
+    ('ampdu_status', 'IHBB'),
+    ('vht', 'HBB4sBBH'),
+]
+
+_STDFRAME = ('ra', 'ta', 'xa', 'seq')
+DOT11_TYPES = {
+    # Management
+    0x00: ('AssocReq', _STDFRAME),
+    0x01: ('AssocResp', _STDFRAME),
+    0x02: ('ReassocReq', _STDFRAME),
+    0x03: ('ReassocResp', _STDFRAME),
+    0x04: ('ProbeReq', _STDFRAME),
+    0x05: ('ProbeResp', _STDFRAME),
+    0x08: ('Beacon', _STDFRAME),
+    0x09: ('ATIM', _STDFRAME),
+    0x0a: ('Disassoc', _STDFRAME),
+    0x0b: ('Auth', _STDFRAME),
+    0x0c: ('Deauth', _STDFRAME),
+    0x0d: ('Action', _STDFRAME),
+
+    # Control
+    0x16: ('CtlExt', ('ra',)),
+    0x18: ('BlockAckReq', ('ra', 'ta')),
+    0x19: ('BlockAck', ('ra', 'ta')),
+    0x1a: ('PsPoll', ('aid', 'ra', 'ta')),
+    0x1b: ('RTS', ('ra', 'ta')),
+    0x1c: ('CTS', ('ra',)),
+    0x1d: ('ACK', ('ra',)),
+    0x1e: ('CongestionFreeEnd', ('ra', 'ta')),
+    0x1f: ('CongestionFreeEndAck', ('ra', 'ta')),
+
+    # Data
+    0x20: ('Data', _STDFRAME),
+    0x21: ('DataCongestionFreeAck', _STDFRAME),
+    0x22: ('DataCongestionFreePoll', _STDFRAME),
+    0x23: ('DataCongestionFreeAckPoll', _STDFRAME),
+    0x24: ('Null', _STDFRAME),
+    0x25: ('CongestionFreeAck', _STDFRAME),
+    0x26: ('CongestionFreePoll', _STDFRAME),
+    0x27: ('CongestionFreeAckPoll', _STDFRAME),
+    0x28: ('QosData', _STDFRAME),
+    0x29: ('QosDataCongestionFreeAck', _STDFRAME),
+    0x2a: ('QosDataCongestionFreePoll', _STDFRAME),
+    0x2b: ('QosDataCongestionFreeAckPoll', _STDFRAME),
+    0x2c: ('QosNull', _STDFRAME),
+    0x2d: ('QosCongestionFreeAck', _STDFRAME),
+    0x2e: ('QosCongestionFreePoll', _STDFRAME),
+    0x2f: ('QosCongestionFreeAckPoll', _STDFRAME),
+}
+
+
+def Align(i, alignment):
+  return i + (alignment - 1) & ~(alignment - 1)
+
+
+def MacAddr(s):
+  return ':'.join(('%02x' % i) for i in struct.unpack('6B', s))
+
+
+def HexDump(s):
+  out = ''
+  for row in xrange(0, len(s), 16):
+    out += '%04x ' % row
+    for col in xrange(16):
+      if len(s) > row + col:
+        out += '%02x ' % ord(s[row + col])
+      else:
+        out += '   '
+      if col == 7:
+        out += ' '
+    out += ' '
+    for col in xrange(16):
+      if len(s) > row + col:
+        c = s[row + col]
+        if len(repr(c)) != 3:  # x -> 'x' and newline -> '\\n'
+          c = '.'
+        out += c
+      else:
+        out += ' '
+      if col == 7:
+        out += ' '
+    out += '\n'
+  return out
+
+
+def Packetize(stream):
+  # pcap global header
+  magicbytes = stream.read(4)
+  if struct.unpack('<I', magicbytes) == (TCPDUMP_MAGIC,):
+    byteorder = '<'
+  elif struct.unpack('>I', magicbytes) == (TCPDUMP_MAGIC,):
+    byteorder = '>'
+  else:
+    raise ValueError('unexpected tcpdump magic %r' % magicbytes)
+  (version_major, version_minor,
+   unused_thiszone,
+   unused_sigfigs,
+   snaplen,
+   network) = struct.unpack(byteorder + 'HHiIII', stream.read(20))
+  version = (version_major, version_minor)
+  if version != TCPDUMP_VERSION:
+    raise ValueError('unexpected tcpdump version %r' % version)
+  if network != LINKTYPE_IEEE802_11_RADIOTAP:
+    raise ValueError('unexpected tcpdump network type %r' % network)
+
+  while 1:
+    opt = {}
+
+    # pcap packet header
+    bytes = stream.read(16)
+    if len(bytes) < 16: break  # EOF
+    (ts_sec, ts_usec,
+     incl_len, orig_len) = struct.unpack(byteorder + 'IIII', bytes)
+    if incl_len > orig_len:
+      raise ValueError('packet incl_len(%d) > orig_len(%d): invalid'
+                       % (incl_len, orig_len))
+    if incl_len > snaplen:
+      raise ValueError('packet incl_len(%d) > snaplen(%d): invalid'
+                       % (incl_len, snaplen))
+
+    opt['pcap_secs'] = ts_sec + (ts_usec / 1e6)
+
+    # pcap packet data
+    radiotap = stream.read(incl_len)
+
+    # radiotap header (always little-endian)
+    (it_version, unused_it_pad,
+     it_len, it_present) = struct.unpack('<BBHI', radiotap[:8])
+    if it_version != 0:
+      raise ValueError('unknown radiotap version %d' % it_version)
+    frame = radiotap[it_len:]
+    optbytes = radiotap[8:it_len]
+
+    ofs = 0
+    for i, (name, format) in enumerate(RADIOTAP_FIELDS):
+      if it_present & (1 << i):
+        ofs = Align(ofs, struct.calcsize(format[0]))
+        sz = struct.calcsize(format)
+        v = struct.unpack(format, optbytes[ofs:ofs+sz])
+        if name == 'mac_usecs':
+          opt['mac_usecs'] = v[0]
+          opt['mac_secs'] = v[0] / 1e6
+        elif name == 'channel':
+          opt['freq'] = v[0]
+          opt['channel_flags'] = v[1]
+        elif name == 'ht':
+          opt['ht'] = v
+          opt['mcs'] = v[2]
+        else:
+          opt[name] = v if len(v) > 1 else v[0]
+        ofs += sz
+
+    (fctl, duration) = struct.unpack('<HH', frame[0:4])
+    dot11ver = fctl & 0x0003
+    dot11type = (fctl & 0x000c) >> 2
+    dot11subtype = (fctl & 0x00f0) >> 4
+    dot11dsmode = (fctl & 0x0300) >> 8
+    dot11morefrag = (fctl & 0x0400) >> 10
+    dot11retry = (fctl & 0x0800) >> 11
+    dot11powerman = (fctl & 0x1000) >> 12
+    dot11moredata = (fctl & 0x2000) >> 13
+    dot11wep = (fctl & 0x4000) >> 14
+    dot11order = (fctl & 0x8000) >> 15
+    fulltype = (dot11type << 4) | dot11subtype
+    opt['type'] = fulltype
+    (typename, typefields) = DOT11_TYPES.get(fulltype, ('Unknown', ('ra',)))
+    opt['typestr'] = '%02X %s' % (fulltype, typename)
+    opt['dsmode'] = dot11dsmode
+    opt['retry'] = dot11retry
+    opt['powerman'] = dot11powerman
+    opt['order'] = dot11order
+
+    ofs = 4
+    for i, fieldname in enumerate(typefields):
+      if fieldname == 'seq':
+        seq = struct.unpack('<H', frame[ofs:ofs+2])[0]
+        opt['seq'] = (seq & 0xfff0) >> 4
+        opt['frag'] = (seq & 0x000f)
+        ofs += 2
+      else:
+        opt[fieldname] = MacAddr(frame[ofs:ofs+6])
+        ofs += 6
+    
+    yield opt, frame
+
+
+def main():
+  if 0:
+    for opt, frame in Packetize(sys.stdin):
+      print opt
+      print HexDump(frame)
+  else:
+    want_fields = [
+        'ta',
+        'ra',
+#        'xa',
+#        'freq',
+        'seq',
+        'mcs',
+        'rate',
+        'retry',
+        'dbm_antsignal',
+        'dbm_antnoise',
+#        'frag',
+        'typestr',
+#        'powerman',
+#        'order',
+#        'dsmode',
+    ]
+    co = csv.writer(sys.stdout)
+    co.writerow(['pcap_secs'] + want_fields)
+    sys.stdout.flush()
+    tbase_pcap = 0
+    tbase_mac = 0
+    for opt, frame in Packetize(sys.stdin):
+      t_pcap = opt.get('pcap_secs', 0)
+      if not tbase_pcap: tbase_pcap = t_pcap
+      co.writerow(['%.6f' % (t_pcap - tbase_pcap)] +
+                  [opt.get(f, None) for f in want_fields])
+      sys.stdout.flush()
+
+if __name__ == '__main__':
+  main()