The HP 5315A and 5315B are universal counters, measuringsignalsovera rangefromO.1 Hz to 100 MHz. The 5315A and 5315B measure frequency, period, time interval, time interval average, time interval holdoff (delay), and ratio. A totalize function with manual or external gating is also provided. All measurements except totalize are displayed in scientific notation with up to eight digits of resolution. Two independent input channels provide time interval measurements. Each input channel has an attenuator (XI, X20), trigger slope selector, trigger level and sensitivity control, and AC-DC coupling. A switchable low-pass filter on Channel A and three-state trigger lights are also provided. Option 003, 1 GHz third or “C” input channel for the 5315A/B, provides frequency measurements from 50 MHz to 1 GHz. The input sensitivity is 15 mV for frequencies between 50 and 650 MHz, and 75 mV for frequencies between 650 MHz and 1 GHz. The C Channel is a 50-ohm input with a dynamic input range of IV rms. The input is prescaled by 10 to achieve a 1 GHz frequency range. Complete specifications for the Option 003 are listed in Table 1-1.