Tektronix 2440 digital oscilloscope

GPIB customization: Set non preset positions without screen underline identification through GPIB commands.

4.3 Trigger System (Stable Signal Display Core)

4.3.1 A/B Dual Trigger System Logic

A trigger is the "main trigger" (the initial condition for initiating data collection), and B trigger is the "delayed trigger" (further filtering of signals after the main trigger). It supports a combination of "main trigger+delayed event/time" trigger and is suitable for capturing signals with specific temporal relationships.

4.3.2 Detailed Explanation of Trigger Modes

Trigger Mode Function Description Applicable Scenarios

AUTO LEVEL automatically adjusts the trigger level to ensure stable display. Even when the signal disappears, regular signals (sine wave/square wave) can still be scanned for quick debugging

Stable triggering when the AUTO signal is present, and stopping scanning when the signal disappears requires clarification of the scene where the signal is present or absent

NORMAL is only triggered when the triggering conditions are met, and when there is no signal, the screen blank captures rare events (such as occasional pulses)

SINGLE SEQ single acquisition, automatically enters SAVE mode after completion to capture single transient signals (such as relay action)

4.3.3 Special triggering function (requires optional support)

Video trigger:

Press the SET Video button to enter the A Video COUPLING menu;

Select synchronization mode (Field 1/Field 2/ALT/TVLINE), only valid for interlaced signals;

Adjust TVLINE to select the trigger wire number, and CLAMP ON/OFF controls whether to clamp the synchronization signal;

Word trigger:

Press the SET WORD button to enter the Word Recognizer configuration menu;

Select encoding (OCT/HEX), clock signal (CLK), trigger word (such as 0x1234);

Only supports Word recognition probes, displaying "WORD PROBE FAULT" when there is no probe.

4.4 Delay function (capturing specific signals after triggering)

4.4.1 Delay by Events

Function: After A triggers, wait for a specified number of B triggering events before completing the collection;

Operation steps:

Press the DELAY → EVENT button to activate the event delay;

Rotate the CURSOR/DELAY knob to set the event count (such as 10, which is the 10th B event triggered for collection after A is triggered);

Press the TRIG STATION button and confirm that the trigger status is "ARMED";

Applicable scenario: Capture the Nth data bit after the master clock in bus communication.

4.4.2 DELAY by TIME

Function: After triggering A, delay the specified time before completing the collection, supporting switching between "main delay" and "Δ delay";

Operation steps:

Press the DELAY → TIME button to activate the time delay;

Rotate the CURSOR/DELAY knob to set the delay time (e.g. 100 μ s);

Press the Δ TIME button to switch to Δ delay mode and adjust the delay time increment;

Applicable scenario: Capture fault signals that occur after a delay in triggering (such as voltage attenuation after power is turned off).

4.5 Acquisition System (Signal Sampling and Processing)

4.5.1 Comparison of 5 acquisition modes

Working principle of collection mode, key parameters, applicable scenarios

Normal sampling, taking 1 sample point every interval - stable signal (sine wave/square wave), pursuing real-time performance

Average: After multiple acquisitions, take the average value to reduce random noise. The average number of times to reduce random noise is 2-256 for signals containing noise (power ripple, sensor output)

Envelope records the maximum/minimum sample points collected multiple times, generating envelope numbers: 1-256 times/CONT Observe the range of signal amplitude fluctuations (such as RF signal amplitude modulation)

Repet is only effective for repetitive waveforms, extending bandwidth to 300MHz - high-speed repetitive signals (clock signals, high-frequency pulses)

Save On Delta real-time comparison between live waveform and reference envelope, automatically stores reference memory when exceeding the limit: REF1-REF4 long-term monitoring occasional anomalies (such as ripple mutation, pulse distortion)

4.5.2 Acquisition mode switching and restart conditions

Switching method: Press the ACQUIRE button and select the mode and related parameters (such as average frequency and envelope frequency) from the menu;

Restart condition: The following actions will restart Average/Envelope collection:

Vertical/horizontal mode change;

Channel VOLTS/DIV or vertical position adjustment;

Change in input coupling method;

Trigger mode or slope change;

Press MENU OFF to close the menu;

Delay parameter change (only in Average mode).

4.6 Storage System (waveform saving and calling)

4.6.1 Waveform Storage (SAVE Button)

Storage objects: CH1/CH2/ADD/MULT waveforms, delayed waveforms;

Operation steps:

Press the SAVE button to enter the SAVEREF SOURCE menu;

Select storage source (such as CH1);

Enter the SAVEREF DESTIATION menu and select the storage target (REF1-REF4);

Confirm storage, the screen displays the prompt "STORED";

Special function: Press the STACK REF button, and the waveform will be automatically stored in the preset order to REF1-REF4 (such as CH1 → REF1, CH2 → REF2).