To measure frequencies that would otherwise exceed the maximum count of the counting register ,the time intercal of the main gate can be reduced,with an appreciate change made to the scale factor .A similar number of pulsed accumulating in the counting register within a 0.1 second ,for example ,would represent a frequency of 455khz；2500pulses counted within 10us is 2.5Mhz,and so forth .Scaling can be done automatically by the positioning of the decimal point on the digital readout ,as the timebase period is switchde from range to range.
Instead of manually switching to the appropriate timer range ,some instruments have an automatic range selection system called auto ranging .The auto range usually consists of a circuit that generates a voltage approximately proportional to th input frequency.Depending on the actual voltage lebel,one of several transistor switches is turned on select the correct timerbade and decimal poing position .
Using the frequency counter as a frequency meter ,however ,is exploiting but one of its several electonic two sinals in the ratio mode ,indicate the time between two points on a waveform ,or do reciprocal counting .