Introduction Your PM 6680B/6681 Timer/Counter is designed to bring you a new dimension to bench-top and system counting. It offers significantly increased performance compared to traditional Timer/Counters. The PM 6680B offers the following advantages: - 10 digits of frequency resolution per second and 250 ps resolution, as a result of high-resolution interpolating reciprocal counting - A 1.3, a 2.7, a 4.2 and a 4.5 GHz input frequency option In addition to the above the PM 6681 offers the following advantages: - 11 digits of frequency resolution per second and 50 ps resolution, as a result of 100 MHz dock in addition to interpolating - Integrated high performance GPIB interface using SCPi commands - Timestamping; PM 6681 records exactly when a measurement is made - A high measurement rate of up to 8500 readings/s to internal memory New powerful and versatile functions A unique performance feature In your new instrument is the complete arming possibilities, which allow you to characterize virtually any type of complex signal concerning frequency and time. For instance, you can insert a delay between the external arming condition and the actual arming of the counter. You can set this delay to a preset time or a number of trigger events, whereby you can for example measure the width of pulse No. 17 after the arming pulse. Read more about Arming in Chapter 5, ‘Measurement Control’. The counter has a multitude of measuring functions such as phase, duty factor, rise/fall-time, peak voltage, and six totalizing modes. The six totalizing modes include simultaneous up/down count (TOT A-B) and the ability to totalize during a preset time after a manual start. The PM 6680B can perform all measuring functions except rise/fall time, on both A and B inputs and all functions except phase, rise/fall time and peak voltage on the E input (arming input).