Abcs of Modulation Domain Analysis
Application Note: CNT-91 + TimeView™
ABCs of Modulation Domain Analysis
Background
An instrument like an Oscilloscope lets you view voltage variations over time. A Spectrum Analyzer lets you view voltage variations over frequency. A Modulation Domain Analyzer (MDA) lets you view frequency variations over time. Figure 1 shows all three dimensions pictorially. To analyze all dynamic properties of a signal, all three of these tools are required: Oscilloscope (v vs. t) Spectrum Analyzer (v vs. f) Modulation Domain Analyzer (f vs. t) While Oscilloscope and Spectrum Analyzer measurements are well-understood, Modulation Domain Analysis requires more explanation. This application note specifically addresses the use of a stateof-the-art frequency analyzer, such as the Pendulum CNT-91, along with TimeView™ software to obtain powerful modulation domain analysis.
Figure 1. A sinewave signal with squarewave FM as shown on an oscilloscope (v vs. t), a spectrom analyzer (v vs. f) and a Modulation Domain Analyzer (f vs. t). These three instruments give a three dimensional view of the signal’s properties. TimeView control & analysis software running on a Windows PC TimeView is connected to the front end frequency analyzer through the PC interface. All settings and controls are accessed through the PC and stored as ASCII files that can be easily imported into various programs. Graphs can be printed on the PC’s printer. CNT-91 Frequency Analyzer The CNT-91 operates on fourth generation frequency counter technology. It incorporates state-of-the-art techniques for improving measurement accuracy. The CNT-91 uses a unique time stamping method that allows for continuous event counting – eliminating “dead time” between counts. The momentary contents of the counter are transferred to memory at regular, pacing intervals. The read out of the register content is synchronized to the input trigger, so it is the event trigger that is time stamped. Each stored time stamp is interpolated “on
ABCs of Modulation Domain Analysis
Background
An instrument like an Oscilloscope lets you view voltage variations over time. A Spectrum Analyzer lets you view voltage variations over frequency. A Modulation Domain Analyzer (MDA) lets you view frequency variations over time. Figure 1 shows all three dimensions pictorially. To analyze all dynamic properties of a signal, all three of these tools are required: Oscilloscope (v vs. t) Spectrum Analyzer (v vs. f) Modulation Domain Analyzer (f vs. t) While Oscilloscope and Spectrum Analyzer measurements are well-understood, Modulation Domain Analysis requires more explanation. This application note specifically addresses the use of a stateof-the-art frequency analyzer, such as the Pendulum CNT-91, along with TimeView™ software to obtain powerful modulation domain analysis.
Figure 1. A sinewave signal with squarewave FM as shown on an oscilloscope (v vs. t), a spectrom analyzer (v vs. f) and a Modulation Domain Analyzer (f vs. t). These three instruments give a three dimensional view of the signal’s properties. TimeView control & analysis software running on a Windows PC TimeView is connected to the front end frequency analyzer through the PC interface. All settings and controls are accessed through the PC and stored as ASCII files that can be easily imported into various programs. Graphs can be printed on the PC’s printer. CNT-91 Frequency Analyzer The CNT-91 operates on fourth generation frequency counter technology. It incorporates state-of-the-art techniques for improving measurement accuracy. The CNT-91 uses a unique time stamping method that allows for continuous event counting – eliminating “dead time” between counts. The momentary contents of the counter are transferred to memory at regular, pacing intervals. The read out of the register content is synchronized to the input trigger, so it is the event trigger that is time stamped. Each stored time stamp is interpolated “on