Tenma 72-9355 - Page 18

18
Operating Math Functions
• Math functions are displays of +, -, ×, ÷ and FFT mathematical results of Channel A
and Channel B.
• Press [MATH] then [F1] to select FFT, +, -, ×, ÷ or OFF as the math type.
Functions Menu Setup Notes
Math
+
-
x
÷
OFF
Signal source 1 + Signal source 2.
Signal source 1 - Signal source 2.
Signal source 1 x Signal source 2.
Signal source 1 ÷ Signal source 2.
Close the math function.
Signal source 1
A
B
Set signal source 1 as Channel A waveform.
Set signal source 1 as Channel B waveform.
Signal source 2
A
B
Set signal source 2 as Channel A waveform.
Set signal source 2 as Channel B waveform.
Vertical range 5mV-50V Display the current math range and adjust with the jog dial.
Shift -- You can shift the math waveform with the jog dial.
Functions Menu Setup Notes
FFT
Hanning
Hamming
Blackman
Rectangle
Set Hanning window function.
Set Hamming window function.
Set Blackman window function.
Set Rectangle window function.
Signal source
A
B
Set A as the math waveform.
Set B as the math waveform.
Horizontal range
305.1 MHz-
244.1MHz
Display the frequency per division (f/div) of the current
horizontal axis.
Vertical range 5mV-50V Display the current FFT range and adjust with the jog dial.
Shift -- You can shift the math waveform with the jog dial.
• Press [MATH] then [F1] select FFT as the math type.
FFT spectrum analysis
• By using the FFT (Fast Fourier Transform) algorithm, you can convert time domain
signals (YT) into frequency domain signals. With FFT, you can conveniently
observe the following types of signals:
• Measure the harmonic wave composition and distortion of the system
• Demonstrate the noise characteristics of the DC power
• Analyze oscillation
How to operate FFT functions
• Signals with DC quantities or offset signals will cause error or offset of FFT
waveform quantities. To reduce DC quantities, select “AC” coupling. To reduce
random noise and frequency aliasing resulted by repeated or single pulse event,
set the acquiring mode of your oscilloscope to “Average” acquisition.
Select the FFT Window
• Assuming the YT waveform is constantly repeating itself, the oscilloscope will carry
out FFT conversion of time record of a limited length. When this cycle is a whole
number, the YT waveform will have the same amplitude at the start and nish.
There is no waveform interruption. However, if the YT waveform cycle is not a