John R. Ambrose is an applications and systems engineering manager with Mixed Signal Integration Corp., San Jose, Calif. Email address: johna@mix-sig.com
3 results found for John R. Ambrose, displaying items 1 - 3
September 14, 2006[Ideas For Design] Add Caliber Determination To Gunshot Detectors
Many communities are installing gunshot detectors on lamp poles to help triangulate the location of gunfire during holidays or to help in responding to "shots fired" 911 calls. Besides location, another piece of useful information is the caliber of the gun that was shot. Fortunately, studies have shown that each caliber has a distinct noise spectrum. Police can use this spectrum to identify the gun's caliber, rather than using loudness, which isn't reliable. The circuit...
April 13, 2006[Ideas For Design] Calculate System THD Without Measuring Noise
Designing total-harmonic-distortion (THD) measurement into a system usually involves a notch filter and a broadband ac measurement. The problem with this technique is that it measures both THD and noise. DSP-based test equipment can calculate just the THD, but this isn't practical for most portable equipment. However, system designers can add THD measurement capability by using a bank of band-pass filters set at the harmonics of the fundamental, along with a notch...
January 20, 2005[Ideas For Design] Standalone Circuit Converts Square Waves To Sine Waves
Many microcontrollers or PICs will have uncommitted digital-to-analog converter (DAC) outputs that can be used to generate sine waves. But these are generally low resolution (8 to 10 bits), yielding a total harmonic distortion (THD) in the 1% range. Or, using a fifth- or seventh-order switched-capacitor filter with a square-wave output ties up two I/O pins on the MCU. One output is used for the filter input and one for the filter clock. Also, the two outputs must be square waves and...
