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for the calibration of frequency sources by adjusting the frequency of
the source until the bar stops moving. The bar should only be used
when the frequency offset is less than 10 Hz because at greater offsets
the beating of the offset and the display update rate can make the bar
appear to stand still even though the offset is still large. Use the dF
readout to reduce the frequency difference to less than 10 Hz, then do
final adjustment using the bar graph display.
The second screen of the PHASE menu displays a frequency
difference measurement made over an elapsed time of up to 32767
hours. This is useful for measuring very small offsets where the phase
change in 1 second is below the FS700's 3° resolution, or where long
duration (24 hour, for example) measurements are desired. Pressing
the EXC key will start or restart the measurement. Following the key
press, the FS700 will keep track of the total elapsed time and the total
signal phase shift (for up to 32767 hours). From this data the frequency
offset is continuously calculated and updated once a second. Thus, the
frequency difference over any time interval may be obtained simply by
waiting the desired elapsed time and reading the display.
dPhase displays the total phase shift since the start of the
measurement. This number is displayed in degrees in scientific
notation. The FS700 can monitor phase shifts up to ±16 million
degrees. Meas Time is the elapsed time of the measurement in hours,
minutes, and seconds. dF is the fractional frequency offset and is
calculated from the equation:
Time Menu
The TIME menu displays, and allows the user to set the time of day.
The time is set by entering the current time on the keypad with the
hours, minutes, and seconds separated by decimal points. Pressing
the EXC key sets the time. This time display accuracy is only as good
as the person pressing the button. However, once set, the clock will
neither gain nor lose time.
DPhase = 1.09E02°
dF = 5.6 E-12
Meas Time = 3:12:57 (EXC = Start)
Time of Day:
12:34:56
