Agilent Technologies DC122 Benutzerhandbuch

 

1.  Clicking on the white numeric display of the voltage scale will show a pop-up list. Select the desired gain 

setting with the mouse pointer. 

2.  Clicking on the Decrement / Increment icons will step the voltage scale up or down to the 

next level for each click of the mouse. 

3.  Clicking Max / Min will toggle to the least sensitive gain setting or to the most sensitive gain setting. 

The input Coupling can be set for AC or DC. The selected setting is shown as an actuated indicator with a green 
backlight. AC coupling blocks DC signal components from the input. The AC coupling mode acts as a high pass 
filter passing frequencies above 10 Hz. In DC coupling all frequency components are passed through the input. 

The input voltage offset control applies an offset to the input amplifier in order to better digitize and display signals 
offset away from 0 volts. Signals riding on a DC level can be most accurately characterized when the offset is 
adjusted so that the acquisitions are made about the midpoint of the digitizer’s Full Scale Range, and when as much 
of the 8-bit ADC range is used as possible. The ability to select an offset voltage enables accurate measurement when 
offsets are present in the signal.  

The Impedance selection allows the user to choose the appropriate internal input termination of 50 

Ω or 1 MΩ.  

The Adv button in this section gives access to the choice of hardware bandwidth limits for the channel.

 

Trigger characteristics are set using the settings in the control panel 
Trigger section. The trigger source setting can be either Internal (trigger on 
any one of the input channels) or External (trigger on an external input). 
The trigger source is indicated in the display by the name appearing under 
Source. 

In order to select the trigger source, click the drop-down source menu in 
the trigger Source section of the control panel and choose the desired one. 

Notice that, for most digitizer models, when external trigger is selected, the 
controls for the trigger termination, 50 

Ω or 1 MΩ, are enabled in the 

Coupling section. Select the desired termination for the external trigger. 

The Coupling section also contains a selection for AC or DC coupling. AC coupling on the trigger sets the trigger 
circuit to an AC Low Frequency Reject mode.  

Use the Level section to set the desired trigger level. The relationship between coupling, trigger source, and trigger 
level was discussed in section 3.4.3 Trigger Level. The 10-bit digitizers have two adjustable trigger levels associated 
with the range of the window trigger. 

The trigger Delay setting positions the acquisition with respect to the trigger. Pre-trigger values are negative and are 
selectable in the range of [0 to – (10 * timebase)]. The value (10 * timebase) is equivalent to the time window or 
capture-time. 100% pre-trigger is achieved by setting the Delay to -capture-time. A 100% pre-trigger delay means 
the trigger point is at the right edge of the display and all of the data in the acquired waveform were captured just 
prior to the trigger event. 

Maximum Post trigger delay settings depend on the sample interval used. Post trigger delays are adjustable up to 
100 Mpoints. 

When a Slope box is shown next to the delay section, selecting the trigger slope is achieved by depressing either the 
positive or negative slope buttons. The 10-bit digitizers extend the functionality of the slope section to allow the 
choice of the window, HF divide, and Spike Stretcher trigger modes when the multiple mode slope button is selected. 
When the Window trigger is chosen buttons below it will allow the user to choose between trigger on entering or 
exiting the window trigger level range.  

The Adv button in this section gives access to the choice of External Trigger range and Bandwidth Limiter. It also 
allows the user to set the offset of the trigger out signal. 

The acquisition mode of the digitizers is selected using one of four 
acquisition mode buttons in the Acquisition section of the control panel. 
Available acquisition modes are Auto, Normal, Single and Stop. 

This Acquisition section of the control panel also indicates the number of 

waveforms acquired per second by the digitizer. The use of each of the acquisition modes is described below. In the