Stanford Research Systems DS345, Manual

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Calibration
6-9
number for a given frequency is: number = 118 + (f - 1000Hz)/312500 Hz
(that is 313500 Hz = 119, 626000 Hz = 120, etc.).
5) Set calbyte 215 to the same value as calbyte 214
Square Wave Symmetry
This calibration corrects the symmetry of the DS345's square wave output.
This calibration depends on frequency and is calibrated at 98 frequency
points in the DS345's frequency range. This calibration should be done after
the square wave amplitude calibration.
1) Set the DS345 to square wave, 1 kHz, 10 Vpp. Connect the DS345's out-
put to the counter with a 50
Ω
terminator. Set the DS345's frequency step
size to 312500 Hz. Set the counter to measure the pulse width of the square
wave input.
At 97 frequencies between 1000 Hz and 30,001,000 Hz in 312500 Hz steps
repeat the following procedure.
4) Set the DS345's output frequency. Adjust the calbyte for this frequency so
that the positive pulse width of the square wave is equal to the negative
pulse width. The calbyte should be in the range 0 to 4095. The calbyte num-
ber for a given frequency is: number = 412 + (f - 1000Hz)/312500 Hz (that is
1000 Hz = 412, 313500 Hz = 413, etc.).
5) Set calbyte 509 to the same value as calbyte 508.