CEM DT-9989, Руководство пользователя, Страница: 52 / 68

3 3 Serial Signal Measurement
3 4 Analyze AC signal by FFT
3 5 Waveform Save
4.1 General fault processing
-
-
-
To measure serial signals, as UART, IIC, SPI and etc, please take following steps:
1. Take 3.1 operations as reference, preliminary observe the measured signal.
2. Press “REC” while signal transmission.
3. Press “NEXT” or “Previous” according to prompt bar on the screen to check corresponding
page.
4. Take 3.2 (1) operations as reference, press “ ”, “ ” and “MODE” to move the cursor,
signal frequency can be measured.
Observe amplifying circuit in device, analyze output harmonic component and observe its
distortion by FFT.
To adopt FFT function, following steps can be taken.
1. Connect the input end of the amplifying circuit to sine wave signal.
2. Connect the oscilloscope probe to output end of amplifying circuit.
3. Take 3.1 operations as reference, proper signal can be observed.
4. Press ‘’F4 (FFT)”, observe frequency spectrum of output waveform for amplifying circuit
after Fast Fourier Transform.
5. Adjust the input signal source of amplifying circuit, observe FFT.
6. Press “F2 (
)” or “F3 ( )” to adjust position of red cursor, read corresponding
frequency and amplitude ratio of dominant wave and harmonic wave.
Waveform data save should be operated under static state, three ways lead to “static” state.
1. Press “HOLD” + “F2 (SAVE)”;
2. Press “REC” + “F2(SAVE)’’;
3. Press “FFT” + “HOLD” + “F1 (SAVE)”;
Then operate according to screen prompts.
1. If turn the oscilloscope switch to any gear, still black screen, no any display, please operates
by following steps:
(1) The Li-ion battery may be used out, please recharge it.
(2) Recharge the battery by matched charger for 5 to 10 minutes, try again.
(3) If still no display, Li-ion battery may be damaged, need to change.
2. Press “AUTO”, if waveform of signal doesn’t display on the screen, please take following
steps:
(1) Verify if the probe is correctly connected to signal cable.
(2) Verify if the signal cable is correctly connected to connector.
(3) Verify if the probe is correctly connected to measured object.
(4) Verify if the measured object emits signals.
Fault Processing 4.
52
Oscilloscope Section