User`s guide

53220A/53230A User’s Guide 73
53220A/53230A Measurements 3
Gate Time/Edge Count The specified (or default) gate time and the input sig-
nal frequency determine the number of edges required to produce the first
reading in the sample count. All subsequent readings in the count are based on
the same number of edges used for the first reading. Gate time is per reading.
Start/Stop Edge The edge that ends the gate time of the previous reading is
the same edge which starts the gate time (edge count) for the next reading.
Because the same edge is used as a start/stop edge, there is no gap/lag/dead
time between readings in CONTinous mode.
Input Signal Stability The stability of the input signal frequency during the
measurement can impact the counter's observable continuous (gap-free) char-
acteristic. As previously mentioned, all readings in the current reading count
are based on the number of edges required to complete the first reading which
in turn, are based on the specified or default gate time. If during measure-
ments before the sample count is reached the input frequency changes, the
counter will modulate the gate time of subsequent readings according to the
frequency. The edge count per reading as originally determined remains fixed
and the readings gap-free.
CONTinuous mode is available on channels 1 and 2 and optional channel 3 of
the 53230A only, and only for frequency and average-period measurements.
Following a reset (*RST) or instrument preset (SYSTem:PREset or Preset
key), the measurement mode is set to AUTO. CONFigure and MEASure do not
change the mode.