Specifications vii
SR620 Universal Time Interval Counter
Specifications
Functions Time Interval, Pulse Width, Rise and Fall Times, Frequency, Period, Phase,
and Event Counting.
Measurement statistics (mean, min, max, standard deviation or Allan
variance) and graphics are available in all modes of operation.
Time Interval Time, Width, Rise and Fall Times
Range -1000 to +1000 s in +/- TIME mode; -1 ns to +1000 s in all other modes
Trigger Rate 0 to 100 MHz
Least Significant Digit 4 ps single sample, 1 ps with averaging
Resolution (((25 ps typ [50 ps max] )2+ (0.2 ppb x Interval)2) / N)1/2 rms
(((25 ps typ [50 ps max])2 + (0.05 ppb x Interval)2) / N)1/2 rms (Opt 01)
Error < ±(500ps typ [1 ns max] + Timebase Error x Interval +trigger error)
< ±(50ps typ[100ps max] + Timebase Error x Interval) (REL)
Arming Modes +TIME Stop is armed by Start
+TIME EXT Ext arms Start
+TIME EXT HOFF Leading EXT edge arms Start, trailing EXT edge arms
Stop.
±TIME Armed by Start/Stop pair
±TIME CMPL Armed by Stop/Start pair
±TIME EXT Armed by EXT input edge
EXT arming may be internally delayed or scanned with respect to the EXT
input in variable steps. The step size may be set in a 1,2,5 sequence from 1
µs to 10 ms. The maximum delay is 50,000 steps.
Display 16 digit fixed point with 1 ps LSD
Sample Rate For a sample size of N, the total sample time is N x(800 µs + measured time
interval) + Calculation time.
The calculation time occurs only after N measurements are completed and
varies from zero (N=1, no graphics, binary responses) to 5 ms (N=1, no
graphics) to 10 ms (display mean or std dev) to 60 ms (display histogram).
Frequency
Range 0.001 Hz to 300 MHz via comparator inputs.
40 MHz to 1.3 GHz via internal UHF prescalers.
RATIO A/B range: 10-9 to 103
Error < ± ((100ps typ [350 ps max])/Gate + Timebase Error ) x Frequency
Gates External, 1 period, 1ms to 500s in 1,2,5 sequence. Gates may be externally
triggered with no delay. Gates may be delayed relative to an EXTernal
trigger. The delay from trigger may be set from 1 to 50,000 gate widths.
Display 16 digit fixed point with LSD = Freq x 4ps/Gate. 1 µHz max. resolution (1
nHz with x1000 for frequencies ≤1 MHz)
Period
Range 0 to 1000 seconds. RATIO A/B range: 10-9 to 103
Error < ±((100 ps typ [350ps max])/Gate + Timebase Error) x Period
Gates Same as frequency
Display 16 digit fixed point with LSD = 1 ps (1 fs with x1000 for periods ≤1 s)
Phase Phase = 360 x (Tb - Ta) / Period A
Range -180 to +180 degrees (0 to 100 MHz frequency)
Resolution (25ps x frequency x 360 + 0.001) degree
