Measuring Waveforms
TDS 684A, TDS 744A, & TDS 784A User Manual 3–109
If the Re-use Probe Calibration data? menu is displayed, you can choose one of
the following options:
Press OK Use Existing Data (side) to use the Probe Cal data last stored to
compensate the probe.
Press OK Erase Probe Cal Data (side) to erase the Probe Cal data last
stored and use the probe uncompensated.
Press CLEAR MENU on the front panel to retain the Probe Cal data last
stored and use the probe uncompensated.
NOTE. If the Re-use Probe Calibration data menu is displayed, do not select OK
Use Existing Data if the probe currently installed is not of the same impedance
stored for the Probe Cal. For example, if the last Probe Cal stored for a channel
was done with a passive 50 probe installed, do not install a passive 1 M
probe and select OK Use Existing Data if the menu appears. If you do so, most
of any signal you attempt to measure will not be coupled to the input channel
because of the probe to oscilloscope impedance mismatch.
Table 3–10 shows the action the oscilloscope takes based on the probe connected
and user operation performed.
Table 3–10: Probe Cal Status
Probe Cal’d?1
User Action
Type Probe Connected2
Probe Cal’d?1
User Action
Simple Interface3TEKPROBE Interface4
No Doesn’t Matter Initialized Initialized
Yes Power off Initialized
(probe data is retained) Initialized
(probe data is retained)
Yes Power on Can not detect differ-
ent probe: Display Re-use Probe
Calibration Data menu Cal’d Probe: Pass
Different probe: Initialized Different probe: Initialized
Yes Disconnect Probe Initialized Initialized
Yes Connect Probe Can not detect differ-
ent probe: Display Re-use Probe
Calibration Data menu Cal’d Probe: Pass
Different probe: Initialized Different probe: Initialized
1Refers to a channel input that was successfully compensated at the time Probe Cal was last executed for the input channel.
2If no probe is connected, the probe status in the vertical main menu is always initialized.
3A probe with a simple interface is a probe that can convey very limited information to the oscilloscope. Most passive
probes (such as the P6139A) have simple interfaces.
4A probe with a TEKPROBE interface is a probe that can convey additional information. For instance, it might automatical-
ly set the oscilloscope input channel impedance to match the probe, send the oscilloscope a unique probe identification
number, and so on. Some optical probes and most active probes (such as the P6205) have TEKPROBE interfaces.