Engine RPM vs AirmarCAST™

Measure the RPM of an engine by analyzing the sound it makes. Engine RPM listens to the sound of a running engine and uses advanced signal processing algorithms to extract the frequency of that sound and calculate the RPM. This app is primarily for setup and diagnostics of engines. After setting the the number of cylinders and whether the engine is a 2-stroke or 4-stroke engine, the app can work with any internal combustion engine, from diesel tractors to aircraft engines to motorcycles to chainsaws. To use the app you must set an expected RPM range to guide the analysis algorithms to the correct RPM. A real-time graph of the autocorrelation graph is displayed to help in troubleshooting and adjusting the expected RPM range. The analysis requires a clear sound from the engine without excessive interference from extraneous sounds. Do not expect to read the RPM of an engine while other things are making too much noise at the same time. The analysis also requires that the RPM be stable. It cannot read the RPM of an engine that is rapidly accelerating. For this reason, and because of the need for adjusting the expected RPM range, this app should not be considered a drop-in replacement for an operational tachometer. Setup options include update periods from 93 milliseconds to 1.5 seconds, one to 12 cylinders, 2-stroke or 4-stroke, low-pass filtering, and signal clipping. The overall RPM range is 400 to 90,000 RPM (although at any one time, the operational range is typically +/- 30% around a nominal expected RPM). Precision is usually about +/- 10 RPM.

Airmar® CAST™ connects to the Bluetooth®-enabled DST810, DX900+, WX300 multisensors and SmartBoat® modules on your boat, making sensor configuration and calibration easy with intuitive app navigation and real-time data from your multisensor. View data on detailed gauges and digital data screens, and perform speed, temperature, and attitude calibrations without the need for additional converters or cables. With CAST, you can configure your multisensor directly, regardless of the other displays and gauges on board. All data configurations and calibrations are stored in the multisensor and delivered on the NMEA2000® network. When used with DST810, you can calibrate basic or heel-compensated speed through water using your on-board GPS speed for comparison. Intuitive wizards guide you through multiple runs to correct for current. Or take it a step further to advanced speed calibration, with up to five heel angles and ten reference speeds. Until now, advanced speed calibration was only possible through expensive PC based software. With Airmar’s SmartBoat® modules, the CAST app delivers the fastest connection to the SmartView software for system configuration.