USO DEL CANAL PRINCIPAL
CAPITULO 2 DISPOSICIONES PARA LA NAVEGACIÓN
You can select a math operator for the function, and the waveform source for the operand or operands.
Operator
The Operator softkey menu is shown at the lower left.
You can select any of the 12 math functions as the math operator to act on the operand or operands. To see the resultant waveform, simply turn the function display to on.
Magnify Magnifies the waveform on operand 1. This allows different
vertical and horizontal scales to be shown similar to the time base windowing feature.
Invert Inverts the waveform on operand 1.
Add Adds, point by point, operand 1 and operand 2. Use add to
compare two waveforms. Simply invert one of the waveforms. Make sure that the vertical sensitivity and offset settings are identical for both waveforms. Then, use the add function to add the waveforms together.
Subtract Subtracts, point by point, operand 2 from operand 1. Use
subtract to make a differential measurement.
Multiply Multiplies, point by point, operand 1 and operand 2. Use
multiply to make power measurements.
Divide Divides, point by point, operand 1 by operand 2. Define Function
Versus Draws a volts versus volts display of the two selected operands.
The bandwidth of both the X and Y axis is the full bandwidth of the oscilloscope’s vertical input. Use versus to compare frequency and phase relationships between two signals.
Integrate Calculates the integral of operand 1. Use integrate to
calculate the energy of a pulse in volt-seconds.
Differentiate Calculates the discreet derivative of operand 1. Use
differentiate to observe the rate at which a signal is changing. For example, you can observe the slew rate of an operational amplifier.
Min Minimum stores the minimum value acquired in each time bucket
on operand 1.’
Max Maximum stores the maximum value acquired in each time bucket
on operand 1
The results for minimum and maximum are recalculated when any of the following occurs:
•
Time base scale, position, or reference is changed.•
Channel state, scale, or offset is changed.•
Trigger definition is changed.•
Acquisition mode, record length, or sampling rate is changed.•
Additional data is stored to a waveform memory that is used as part of a function.•
The oscilloscope is turned off and on.•
The Clear display key is pressed.•
When the Run key is pressed after the oscilloscope was stopped.FFT magnitude Generates a new waveform by using a fast Fourier
transform (FFT).
See Also Chapter 21, "FFT Menu," for a detailed description of the FFT features and functions.
Math Menu
Define Function
Operand
The math operator is performed either on operand 1, or on operand 1 and operand 2. The number of operands used depends on the math operator you select. For example, add requires two operands while invert requires only one operand.
Operand lets you select from channels, functions, waveform memories, or a constant.
•
If the operand waveforms have different record lengths, the function uses the shortest record.•
If two operands have the same time base scale, the resulting function has the same time scale which results in the proper time scale for the function.•
Constant operands have the same time scale as the associated waveform operand.•
A waveform function operand is acquired even if its display is turned off.•
Function 1 is allowed as an operand for function 2. This allows you to construct equations with up to two operators and three operands.Display
When you set the display to on, the softkey menu displayed depends on which math operator you select. When magnify, versus, or FFT magnitude is the operator, the function scaling softkey replaces the vertical softkey. The display softkey turns on the display of the function, and it allows you to adjust the size and position of the newly generated waveform (function) for easily viewing the waveform and for easily making measurements. You can use the knob, arrow keys, or keypad to size and position the function. Software expansion is used to resize the function when you change the display controls. It does not change the way the hardware acquires the data. When display is set to on, the function is calculated and displayed. Turning the display to off ends function computation and erases the function from the display.
Function 1 is displayed in the same color that is used to display signals from slot 1, and function 2 is displayed in the same color that is used to display signals from slot 2.
Vertical
You can set the scale to track the source waveform or you can adjust the scale manually with the scale and offset keys.
In the HP 54710A, 54710D, 54720A, and 54720D, functions are limited to 32K points. On a waveform exceeding this length, functions are calculated on the first 32K points of the waveform.
Scale
Scale changes the vertical size of the function, so that it is not clipped or too small on the display.
Offset
Offset positions the function vertically on the display.
Math Menu
Display
Function scaling
When magnify or versus is the operator, the function scaling softkey replaces the vertical softkey. When you select function scaling, a second level softkey menu allows you to change the vertical and horizontal scaling of the function. Refer to Chapter 21, "FFT Menu," for a description of the FFT scaling
functions.
Vertical
Vertical allows you to select either track source or manual. Track source makes the function use the same vertical scale and offset of the function’s waveform source. Manual allows you to set the vertical scale and offset independently of the waveform source.
Horizontal
Horizontal allows you to select either track source or manual. Track source allows the function to use the same horizontal scale and position as the waveform source. Manual allows you to set the horizontal scale and position of the function independently of the settings for the waveform source.
13
Measurements
This chapter describes the process the oscilloscope uses to make waveform measurements. It also describes the parameters that are measured and how to set up measurements for the best solution. Like any tool, it is important to understand how to use the tool, its
limitations, and methods that may overcome some of the shortcomings.
The waveform in figure 13-1 shows the pulse parameters that the oscilloscope measures. Hewlett-Packard has been using these parameters in its measurements for the past 10 years. This chapter defines these parameters and discusses how they are measured.