| Tide
Measurement System
Specified and developed under contract to the Naval Oceanographic Office, the Tide Measurement System (TMS) is used to support hydrographic |
| mapping operations around the world. TMS is a pressure-based telemetering system used to measure tide height and wave activity at multiple shore locations, and automatically transmits the data via UHF or VHF radio telemetry to an offshore survey ship |
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| TMS observes tide height by measuring the pressure due to the weight of the water column. TMS incorporates high-accuracy water and air pressure sensors. TMS can measure tide height to an absolute accuracy of 1 cm. | |
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TMS is also a real-time telemetry system, which transfers data from the shore station, automatically or upon command, to a ship located up to 20 nautical miles offshore. Data telemetry can be scheduled from the ship to optimize power consumption and ensure error-free transmission. |
| TMS can be adapted for use in long-term or short-term projects. For long-term projects, TMS collects tide data at 15 minute intervals or less and can save many days of data for subsequent transmission. TMS can operate in this mode for about 60 days. Alternatively, the TMS can sample and telemeter much more rapidly (every few minutes) for a shorter period of operation. This mode of operation might be appropriate, for example, during intensive real-time bathymetric surveys. | |
| Sensor Specifications: | |
| Water Pressure | |
| Sensor | Paroscientific DigiQuartz |
| Absolute Pressure Sensor | |
| Model | 8DP-020 (with pressure housing) |
| Range, FS | 0 to 45 psia (corresponds to 0 to 20 m tide height) |
| (other ranges available) | |
| Accuracy | +/-0.01% FS (equivalent to +/-0.2 cm tide height) |
| Resolution | 0.0015% FS (equivalent to 0.03 cm tide height) |
| Air Pressure | |
| Sensor | Setra Model 270 Barometer |
| Range | 800 to 1100 mb |
| Accuracy | ±0.05% FS (equivalent to 0.5 cm tide height) |
| Resolution | 0.01% FS |
| Water Temperature | |
| Sensor | Paroscientific Temperature Sensor |
| (mounted inside Pressure Sensor) | |
| Range | -2oC to 40oC |
| Accuracy | ±0.1oC |
| Resolution | 0.005% FS |
| Telemetry System Specifications: | ||
| Modem | ||
| Type | Packet Radio | |
| Manufacturer | Pac-Comm | |
| Model | EWM-1200 | |
| Baud Rate | 1200 | |
| Radio Transceiver | ||
| Type | Amplitude Modulation, Mobile Transceiver | |
| Manufacturer | E.F. Johnson | |
| Model | Challenger 7164 | |
| Frequency | 150 to 174 MHZ standard | |
| Range | (other VHF and UHF bands available) | |
| Channels | 8 push-button selectable on front panel | |
| Programmable channel pre-set | ||
| Power Output | 25 to 40 watts | |
| Power System Specifications: | |
| Energy Storage Unit | |
| Type | 12 volts sealed gel-cell lead-acid storage battery |
| Manufacturer | Gel-tech |
| Capacity | 115 amp-hours nominal |
| AC Power Input | |
| Type | Universal input switching AC/DC power supply |
| Manufacturer | Power General |
| Model | PR-12 |
| Input Voltage | 95 to 265 volts AC |
| Input Frequency | 47 to 440 Hz |
| Output Voltage | 13.8 volts DC +/- 0.1 volt (battery maintaining) |
| Power Output | 150 watts at 20oC |
| Current Limiting | 10 amps or power limit |
| Solar Power Regulator | |
| Manufacturer | Bobien |
| Max Current | 8 amps |
| DC Power Input | |
| Type | Wide range DC/DC converter |
| Manufacturer | International Power Sources, Inc. |
| Model | LT103 |
| Input Voltage | 9 to 32 volts DC |
| Output Voltage | 13.8 volts DC ±0.1 volts |
| Power Output | 30 watts |
| SeaPac 2252 Specifications | |
| Data
Acquisition, Processing,
and Storage Archival Data Storage |
|
| Medium | Non-volatile flash PCMCIA card |
| Capacity | Typically 20 MByte, 6,000,000 - 24 bit |
| pressure samples expandable to 170 Mbyte | |
| Retrieval | Stand-alone RS-232, 300 to 19200 baud |
| directly with 16 command instruction set; OR transfer memory card to computer and the data will appear as a single MS-DOS file called flashpac.dat, then export the data to computer hard disk. NO wait for data offload! | |
| Data Security | CRC error checking, overwrite protection |
| Telemetry Buffer Data Storage | |
| Medium | RAM on SeaPac 2252 CPU board |
| Capacity | 32 KB |
| Retrieval | Data collected since last transmission is |
| telemetered | |
| Timebase | |
| Type | On-board battery-backed real-time clock |
| Crystal | 2.097152 MHZ GT-cut quartz crystal |
| Stability | +/-1ppm over 0oC to 40oC |
| Accuracy | +/-30 seconds/year |
| Shipboard Base Station Specifications |
| Telemetry System |
| Same as shore station, except rack mounted |
| Control/Display Computer | |
| Type | IBM-compatible Pentium Desktop PC |
| Operating System | Windows NT 4.0 |
| Hard Disk | >4 Gigabyte |
| Monitor | 17" SVGA |
| Software | |
| Name | TMS |
| Vendor | WHISL |
| Calculated Tide Height | |
| Tide Height
in centimeters is calculated at the base station from
telemetered absolute water pressure, and estimated water density. |
|
| Accuracy | +/-1 cm (assumes water density is known to |
| within +/-0.05% | |
| Sampling and Telemetry Schedule Options |
| Tide Measurement Schedule |
| Measurement Period (Integration
interval):
2 to 60 minutes (even values only) Centered on the hour and measurement intervals |
| Interval between Measurements (sampling
interval):
Any integral number of minutes divisible into 1440 Minimum: Measurement Period + Telemetry Window Length + 2 minutes |
| Timestamp:
Center of Measurement Period Always on the hour and at fractional hour intravals |
| Wave Measurement Schedule | |
| Measurement Period: | 0.25, 0.5, 1.0, or 4.0 seconds |
| Burst Length:
Any integral number of minutes divisible into 1440
Minimum: Burst Length + Telemetry Window + 2 minutes |
|
| Measurement/Burst: | 8 to 4096 in multiples of 8 |
| Telemetry Schedule |
| Telemetry Window Length:
Any integral number of minutes; Minimum: 1 minute |
| Telemetry Window Interval:
Every N tide measurements Minimum: every tide measurement (N=1) Maximum: every 48 tide measurements (N=48) |
| Coastal Sciences, Engineering & Planning |  |
| Aquatic Environmental Assessment |  |
| Oceanography & Measurement Systems |  |
| For more information please call or e-mail
the
Senior Scientist & Senior Oceanographer: Bruce A. Magnell at (508) 495-6223 bmagnell@whgrp.com or the Vice President of Marketing and Sales: Kevin McCarthy at (508) 495-6245 kmccarthy@whgrp.com |
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Woods
Hole Group
Marine Environmental Solutions 81 Technology Park Drive, East Falmouth, MA 02536 Tel: 508-540-8080 Fax:508-540-1001 © 2002-2003, Woods Hole Group, Inc. |