Engine RPM vs QuickScanPDF+

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.

QuickScanPDF turns paper assignments, forms, notes, and receipts into clean PDFs from your phone. Scan a page, add more pages when needed, review the document, make quick fixes, then prepare one PDF to share or save. FEATURES: • Scan documents with automatic edge detection and perspective correction. • Add pages to the same document with Next Page and review them together before export. • Fine-tune page corners and perspective when a scan needs a manual boundary fix. • Clean pages with Auto Clean, Brighten, Sharpen, or Remove Background presets. • Choose PDF quality and optimize for balanced output, crisp text, or a smaller file. • Prepare class submission, email, backup, or preview shares through the iOS share sheet. • Free exports include a small "Made with QuickScanPDF" watermark; Premium removes it. • Keep scans on device in Documents with names, page counts, file size, and export status. SUBSCRIPTION INFORMATION: • Free trial available - try Premium before subscribing. • Subscription automatically renews unless canceled at least 24 hours before the end of the current period. • Payment will be charged to your Apple ID account at the confirmation of purchase. • Your account will be charged for renewal within 24 hours prior to the end of the current period. • You can manage and cancel your subscriptions by going to Settings Apple ID Subscriptions. Privacy Policy: https://hatchingpoint.com/quickscanpdf/privacypolicy Terms of Use: https://hatchingpoint.com/quickscanpdf/terms