Chapter 5 321
Programming
Math Functions
EXAMPLE 1
10 OUTPUT 718;"IP;SNGLS;CF 300MHZ;SP 20KHZ;RB 10KHZ;RL
−10DBM;LG 5DB;TS;"
20 OUTPUT 718;"CLRW TRA; CLRW TRB;TS;"
30 OUTPUT 718;"VIEW TRB;DL −16DBM;"
40 OUTPUT 718;"AMBPL ON;"
50 END
Line 10 executes an instrument preset, then uses the calibration signal
to simulate uncorrected data. The program sets the reference level to
−10 dBm, the span to 20 kHz, the center frequency to 300 MHz, the
resolution bandwidth to 10 kHz, the log scale to 5 dB, and the sweep to
single mode.
Line 20 sets traces A and B to clear-write mode and takes data into
both traces.
Line 30 sets trace B to view mode in order to freeze the data in this
trace. Use the display line to indicate where you want the corrected
data to appear on the screen; for this example, the display line is set to
−16 dBm.
Line 40 executes the function AMBPL. Trace B is subtracted from
trace A; because the traces are identical, the result is a flat response
equal to 0 dBm. Note, however, that the reference level is at −10 dBm; if
this were the end of the calculation, you would not be able to see the
result. The display line is added to move the response to −16 dBm and
onto the screen where you can view the result.
Adding and Subtracting in Volts
In linear mode, all trace math is executed in positive-voltage units. This
means that the APB command moves trace A data up the screen, while
the AMB command moves trace A data down the screen (assuming
trace B contains non-zero data).
To illustrate the difference between trace math in log mode and in
linear mode, see Example 2. Here, both trace A and trace B are set to
mid-screen values. When in log mode, the result of executing "AMB
ON" appears at the top of the screen. When in linear mode, the result
appears at the bottom of the screen.
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