Understanding precipitation is challenging. In most cases involving very low or very high rain rates, mechanical rain gauges will perform poorly and underestimate both high and low rain rates. OSI engineers have developed a series of optical technologies to measure precipitation induced optical scintillations. The APG-815-DS (All Precipitation Gauge) uses OSI’s proven and patented optical scintillation technology to serve as both a rain gauge (precipitation rate and accumulation) and a snow gauge (water equivalent rate and water equivalent accumulation).
The APG-815 is a unique and very advanced sensor for measurement and discrimination of the various types of precipitation, unmatched by any other technology in terms of accuracy, performance, high reliability and its ultra-low maintenance design.
The ORG/APG/OWI family of sensors all use the same digital DSP "engine" technology for practical unattended weather observations and will provide critical ground truth to satisfy global-scale precipitation and climate monitoring requirements.
Even our first generations optical weather sensors - the LEDWI - of which 1100 have been fielded with one in every airport throughout the US as part of the National Weather Service (NWS) ASOS program are all still in operation 25 years later!
OSI is the only sensor manufacturer in the entire ASOS program that has not been totally replaced at least one time.
Do you want to better understand
Storm water precipitation?The APG-815-DS data string includes:
Time, Weather code, Rain rate in inch/hour or mm/hour, Accumulated rain in inches or mm, Diagnostic, Carrier strength, Raw signal, Baseline and Temperature in Fahrenheit or Celsius.Specifications and features that together are unique to the APG:
- Measurement principle: Optical Scintillation (far more reliable than optical scatter and mechanical techniques)
- Algorithms continually refined from over 800 million hours of proven field operation in applications on every continent
- All digital / DSP based design with no temperature sensitive analog components
- No Moving Parts
- No small collection or measurement orifices to get clogged with dirt / debris
- No need for high power heaters or chemical antifreeze for snow measurement
- No periodic maintenance required
- No scheduled / regular cleaning of optics required
- Insensitive to dirt buildup on optics
- Simple polled / unpolled (user selectable) ASCII data string over RS-232
- Include MODBUS RTU over serial RS-232 I/O format as standard
- Options for RS-485, Ethernet, Limited Distance Modems (LDM) and Cellular Modems
- Discriminates between rain, snow, drizzle, freezing drizzle, freezing rain, etc.
- Ability to add acoustic hail / ice particle sensor (HIP-100)
- Minimum 10 weather identification codes for both NWS and WMO weather codes
- Measurement dynamic range: 0.001 to 500 mm/hr rain, .03 to 500 mm/hr snow
- Optional extended measurement ranges over 500 mm/hr
- Reports both instantaneous rain rate and accumulation
- Rain / snow measurement accuracy: 5% accumulation
- Rain / Snow measurement resolution: 0.001 mm
- Full data update rate; once per minute; Instantaneous intensity every 10 seconds
- Power requirements: nominal 12 VDC / max 400 mA (solar compatible)
- Operating temperature range; -50º to 60º C (-58º to 140º F)
- Built-in continuous self-test / self-diagnostics and performance monitoring
- Ultra-reliable operation 24/7/365 with virtually zero maintenance
- Mean-Time Between Failure (MTBF) in excess of 80,000 hours
- No adverse effects from high winds, evaporation, and other common errors of mechanical gauges
- Technology field proven for over 30 years (long track record)
- Can operate on unstable / tilting platforms such as data buoys and ships
- Easy installation / no cement pads; simply clamp to a 1.5-2" pipe w provided U-bolts
- Widely used by NOAA / NWS, military, airports, state DOTs, etc.
All APG ( and OWI sensors) have Modbus RTU built-in.
A little clarification. Modbus is a protocol (another is ASCII output) and it can be used with different physical links (RS232, RS422, RS485....). Since the physical output on APG is RS232 (Modbus RTU), if you want to have a TCP/IP output, then you will need to order the Moxa Modbus TCP/IP convertor.
