whirm@sphynx:/tmp$ gpsbabel -t -r -w  -i garmin -f /dev/ttyUSB0 -o gpsdrive -F blah.gpsdrive
[ERROR] PROTOCOL ERROR: Unknown tag/data [D/304]

[ERROR] PROTOCOL ERROR: Unknown tag/data [A/1000]

[ERROR] PROTOCOL ERROR: Unknown tag/data [A/1002]

[ERROR] PROTOCOL ERROR: Unknown tag/data [A/1003]

[ERROR] PROTOCOL ERROR: Unknown tag/data [A/1004]

[ERROR] PROTOCOL ERROR: Unknown tag/data [A/1005]

[ERROR] PROTOCOL ERROR: Unknown tag/data [A/1006]

[ERROR] PROTOCOL ERROR: Unknown tag/data [A/1007]

[ERROR] PROTOCOL ERROR: Unknown tag/data [A/1008]

[ERROR] PROTOCOL ERROR: Unknown tag/data [A/1009]

[ERROR] A301_GET: Unknown track protocol
[ERROR] A200_GET: Non Pid_rte_Wpt_Data
whirm@sphynx:/tmp$