The HP 5315A Universal Counter measures signals over 0.1Hz to 100MHz range. Measurement Period: 10 ns to 105 Sec. Time Interval: 100 ns to 105 Sec. Time Interval Average: 0 ns to 105 Sec. Time Interval Delay: holdoff, variable delay of nominally 500 µs to 20 ms between START (channel A) and STOP (channel B). And Ratio: 0.1Hz to 100MHz, both channels. A totalize function with manual or external gating is also provided. All measurements, except totalize, have up to 8-digits resolution. Two channels provide time interval measurements. Includes: Option 001 = TCXO Timebase.