Acoustic Rain Gauge
• Attempt to estimate rainfall and wind strength from sound spectrum
• 16 frequency bins from 500 Hz to 50 kHz• Hydrophone hangs 30m under buoy• Hydrophone and acoustic processing electronics
from Metocean• We added data logger and Orbcomm telemetry
ARG buoy Orbcomm
• 3 messages per hour• 466 bytes total per hour• Panasonic is active for approx. 20 min per hour• This is programmed using KXB command• If message buffer starts to get full, Panasonic is
switched to continuous mode
Land Station Rain Gauge
• 12 months at SOC• Sends 2 messages/hour• 294 bytes total per hour• Samples rain level and
temperature every minute
Land Station Messages
SOC Orbcomm Message Delays (rainb3)
0
5
10
15
20
25
30
12-Oct 19-Oct 26-Oct 02-Nov 09-Nov 16-Nov 23-Nov 30-Nov 07-Dec
Saturdays
Ho
urs
/ N
um
ber
of m
essa
ges
in b
uff
er
msg buffer
Delay
Expanded View – 1 week
SOC Orbcomm Message Delays (rainb3)
0
2
4
6
8
10
12
23-Nov 24-Nov 25-Nov 26-Nov 27-Nov 28-Nov 29-Nov 30-Nov
Saturdays
Ho
urs
/ N
um
be
r o
f m
es
sa
ge
s in
bu
ffe
r
msg buffer
Delay
Message delays during October-November 02
• Maximum delay was 25 hours. Caused by mail server failure at SOC
• Average delay – 1.22 hours
• Median delay – 0.25 hours
• Daily pattern probably caused by interference from Vodaphone paging system
Comparative costs
Orbcomm Iridium
• Receiver + antenna €1000
• Airtime €65 per month flat rate
• (Same as Iridium with 1 minute per day)
• Receiver + antenna €2000
• Airtime €18 per month plus €1.6 per minute