Aloha Proof Module Design

1. Aloha Proof Module Design Cabled Observatory Presentation School of Ocean and Earth Science and Technology February 2006

2. 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

3. 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.

5. End Cap w/ DQ and HYD

6. Microcontroller Power Supply DigiquartzDQ (under) .

7. Hydrophone ADC Manchester

8. Top ViewManchester ADC HydrophoneMicrocontroller& DQ Power Supply Digiquartz

9. Power Supply • The proof module has a shunt regulator- based power supply consisting of three sections: • Linear Shunt Regulator • DC/DC converters • Filtering

10. 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.

11. 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.

12. 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.

13. 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.

14. 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

15. 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.

16. 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

17. Sample Serial Stream