Download Proof Module - School of Ocean and Earth Science and Technology

Aloha Proof Module Design
Cabled Observatory
Presentation
School of Ocean and Earth Science and Technology
February 2006
Purpose
• Proof of Concept
• Long term testing of data communications
capabilities.
• Prepare for full observatory phase 2
deployment:
– Any modifications learn from phase 1
– H4 cable cut and emplacement
– Cable termination emplacement
Proof Module Overview
• The proof module has no supervisory command
and control.
• The proof module monitors engineering status,
data communications, and system operation.
• The proof module has no customers, but
includes two internal instruments:
– Wide amplitude and frequency range hydrophone
– Digiquartz pressure sensor
– Continuous pressure spectrum from DC to 40KHz
• The proof module has no time stamp capability,
but timing will be accomplished at the shore
station.
End Cap w/ DQ and HYD
Microcontroller
DQ (under)
Power Supply
Digiquartz
.
Hydrophone
ADC
Manchester
Top View
Manchester
ADC
Hydrophone
Microcontroller& DQ Power Supply Digiquartz
Power Supply
• The proof module has a shunt regulatorbased power supply consisting of three
sections:
– Linear Shunt Regulator
– DC/DC converters
– Filtering
Shut Regulator Section
• Input power to the shunt regulator is 12
VDC at 1.6 amps (20 watts).
• This provides the input voltage to the
DC/DC converters.
• All power not used by the DC/DC
converters is dissipated in the shunt
regulator.
DC/DC converter Section
• The digital and analog electronic circuitry
operate from two DC/DC converters:
– 5 VDC @ 2 Amps Max
– +/- 12 VDC @ .33 Amps Max
• Due to the switching characteristic (noise) of
DC/DC converters this section is enclosed in the
emission-shielding metal box.
• Box penetration feed-thru capacitors are used
for all DC voltage and return wires.
• Temperatures are monitored and also penetrate
the box using feed-thru capacitors.
Filter Section
• A final section inductor/capacitor filter is
used to provide clean noise free power.
• The hydrophone is being operated with a
wide amplitude dynamic range of 24 bit
ADC capability.
• The power supply filtering is for the analog
sections:
– hydrophone preamplifier, and
– hydrophone analog to digital converter.
Communication
• The instrument data is provided over 12.288
MHz, Manchester encoded/decoded data
stream.
• This is 96,000 – 64-bit frames/second.
• Within each frame are:
– Two 24 bit digitized analog channels of the
hydrophone.
– Two single bit RS232 embedded serial
communications 9600 baud. One primary and a
secondary backup.
– Six bits for frame synchronization.
– Eight unused (zeroed) bits.
Digiquartz
• The Digiquartz is a digital pressure gauge.
• 32 bit counters
– Raw count (for high resolution with long periods)
– Period count (for quick updates at lower resolution)
• Depth is calculated from the 32kHz variable pressure
sensor where frequency is directly proportional to depth.
• Resolution is directly proportional to the integration time.
• Temperature compensation is calculated from the
170kHz variable temperature sensor where frequency is
directly proportional to temperature.
• The Digiquartz is the same used in NOAA DART buoys
to detect tsunami
Hydrophone & ADC
• The analog signal from the hydrophone is
digitized with a two channel 24 bit ADC.
• Channel 1 (seismic) is a wide frequency
range from 100 seconds to 40 kHz.
• Channel 2 (audio) is a narrow frequency
range from 10 Hz to 40 kHz.
• With digital sampling is 96,000 samples
per second the analog is low pass filtered
at 40 kHz to minimize aliasing.
Serial Data Stream
• The serial data stream provides both
engineering and Digiquartz data.
• Engineering data:
–
–
–
–
5 DC/DC power supply voltages
2 cable and sea water return voltages
1 current of H4 cable
4 temperatures
• Diqiguartz data:
– 2 depth & temperature period counts
– 2 depth & temperature free run counts
– Calculations of depth with temperature compenstaion
Sample Serial Stream