Markers

How to Create Markers

Using front-panel
hardkey [softkey] buttons

Using Menus

1. Press Marker

2. then [Marker n]

1. Click Marker/Analysis

2. then Marker

3. select a marker number

Marker dialog box help

Marker  Specifies the current (active) marker number that you are defining.

On  Check to display the marker and corresponding data on the screen.

Stimulus  Specifies the X-axis value of the active marker. To change stimulus value, type a value, use the up and down arrows, click in the text box and use the front-panel knob, or drag the marker on the screen.

Delta (and Reference) Markers  Check to make the active marker display data that is relative to the reference (R) marker.  There is only one reference marker per trace. All other markers can be regular markers or delta markers. When a delta marker is created, if not already displayed, the reference marker is displayed automatically. A delta marker can be activated from the Marker dialog box or the Marker Toolbar. See Also: Number of General Purpose and Reference Markers.

Discrete Marker  Check to display values at only the discrete points where data is measured. Clear to display values that are interpolated from the data points. The interpolated marker will report y-axis data from ANY frequency value between the start and stop frequency.

Fixed  Check to cause the marker to have a fixed X-axis and Y-axis position based on its placement on the trace when it was set to fixed. It does NOT move with trace data amplitude. It can be scrolled left and right on the X-axis by changing the marker stimulus value. Use this marker type to quickly monitor "before and after" changes to your test device. For example, you could use fixed markers to record the difference of test results before and after tuning a filter.

Clear the box to create a Normal marker, which has a fixed stimulus position (X-axis) and responds to changes in data amplitude (Y-axis). It can be scrolled left and right on the X-axis by changing the marker stimulus value. Use this marker type with one of the marker search types to locate the desired data.

(Marker) Format  Displays the marker data in a format that you choose. The Trace Default setting has the same marker and grid formats. Choose from the following:

Noise Marker Format - Available ONLY in IMSpectrum and SA measurement classes. For comparison purposes, electronic noise measurements are often displayed as though the measurement was made in a 1 Hz Res BW. However, making an actual measurement at a 1 Hz Res BW is impossible, and at 10 Hz, extremely slow.

A Noise Marker mathematically calculates the noise measurement at that single data point as though it were made using a 1 Hz bandwidth.

To accurately measure noise, the Noise Marker should NOT be placed on, or too close to, a signal. The distance from a signal depends on several factors. To know if an accurate reading is being made, move the Noise Marker until consistent measurements are displayed in adjacent data points.

All Off  Switches OFF all markers on the active trace.

Coupled Markers

The coupled markers feature causes markers on different traces to line up with the markers on the selected trace. Markers are coupled by marker number, 1 to 1, 2 to 2, 3 to 3, and so forth. If the x-axis domain is the same (such as frequency or time), coupling occurs. Trace markers in a different x-axis domain will not be coupled. If a trace marker has no marker to couple with on the selected trace, the marker remains independent.

Coupling Method - Determines the scope of coupling. Choose from the following:

• Channel – Traces that are associated with the same channel are eligible to have their markers coupled.  For example, all traces on Channel 1 have their markers coupled.  Changing a marker stimulus or ON | OFF state on a trace associated with Channel 1 has NO effect on markers on Channel 2 traces.

• All – All traces on all channels will be eligible to have their markers coupled.

Coupled Markers Model

This model simulates the use of coupled markers in the VNA:

1. Click Trace A or Trace B

2. Click Coupled Markers

3. Notice the following:

1. • Markers on the unselected trace move to the x-axis position of the selected trace.

   • If a marker number on the unselected trace has no corresponding marker on the selected trace, no movement occurs for that marker.

4. Click Reset to run the model again. There is no Reset for coupled markers on the PNA.

How to Search with Markers

Using front-panel
hardkey [softkey] buttons

Using Menus

1. Press search

1. Click Marker/Analysis

2. then Marker Search

Marker Search dialog box help

Marker  Specifies the marker that you are defining. Not available for search types that deploy specific markers.

Search Domain  Defines the area where the marker can move or search. For full span, the marker searches for specified values within the full measurement span. For user span, the marker searches for specified values within a measurement span that you define. Learn more about Search Domain.

Search Type

Note  You must either press Execute or check Tracking to initiate all search types.  If there is no valid data match for the search type, the marker will not move from its current position.

• Execute  Click to cause the marker to search for the specified criteria.

• Tracking  Check to cause the marker to search for the specified criteria with each new sweep. The searches begin with the first sweep after Tracking has been checked, based on the current search type and domain information. Therefore, make sure that the search criteria are in the desired state before using the data. You cannot manually change the stimulus setting for a marker if Tracking is selected for that marker.

Maximum  Marker locates the maximum (highest) data value.

Minimum  Marker locates the minimum (lowest) data value.

Next Peak  Marker locates the peak with the next lower amplitude value relative to its starting position.

Peak Right  The marker locates the next valid peak to the right of its starting position on the X-axis.

Peak Left  The marker locates the next valid peak to the left of its starting position on the X-axis.

• Threshold  - Minimum amplitude (dB). To be considered valid, the peak must be above the threshold level. The valley on either side can be below the threshold level.

• Excursion  The vertical distance (dB) between the peak and the valleys on both sides. To be considered a peak, data values must "fall off" from the peak on both sides by the excursion value.

For more information, see What is a Peak?

Target   Enter the Target value. The marker moves to the first occurrence of the Target value to the right of its current position. Subsequent presses of the Execute button cause the marker to move to the next value to the right that meets the Target value. When the marker reaches the upper end of the stimulus range, it will "wrap around" and continue the search from the lower end of the stimulus range (left side of the window).

• If Discrete Marker is OFF, the marker locates the interpolated data point that equals the target value.

• If Discrete Marker is ON and there are two data points on either side of the target value, the marker locates the data point closest to the Target value

Four markers are automatically deployed to find the first negative or positive bandpass in the selected search domain.

To create Bandwidth markers:

1. Press search, then [Bandwidth]

2. Specify the level in dB from the peak or valley where bandwidth is measured.

• Bandwidth Search can be used ONLY with Log Mag display format.

• To use Bandwidth Search on a peak or valley other than the maximum or minimum values, change the Search Domain.

The following four values are displayed for Bandwidth Search:

• BW:  (Marker 3 x-axis value) - (Marker 2 x-axis value) = width of the filter.

• Center:  Mathematical midpoint between markers 2 and 3.

• Q:  Ratio of Center Frequency to Bandwidth (Center Frequency / Bandwidth).

• Loss:  Y-axis value of Marker 4.  This is the loss of the filter at its center frequency.  The ideal filter has no loss (0 dB) in the passband.

Uses the active marker to find the specified gain Compression Level. Learn more about Gain Compression.

Note: Valid ONLY for S21 (Gain) measurements with a Power Sweep.  

To create Compression markers:

1. Press search, then [Compression]

2. Specify the compression level in dB,

3. Optionally press Tracking to search for the specified compression level with each sweep.

Linear gain is defined as the Y-axis value (gain) of the first data point of the Search Domain (Full Span by default).

Marker > N: X-axis value and Y-axis value

Comp Pin: Input power (marker X-axis value)

Comp Pout: Output power (Pin + gain)

Comp Level: Compression level found.

• When Discrete is OFF (default setting) the marker finds the exact specified compression, interpolated between the two closest data points and calculates the Comp Pin and Comp Pout value for that point.

• When Discrete is ON (not interpolated), the marker resides on the closest data point to the requested compression level.

Comp. Not Found: Displayed when the requested compression level is not found.

About PSAT and PNOP Markers

Compression measurements based on the Pout vs Pin curves are common in the satellite test industry. In the case of Travelling Wave Tube (TWT) amplifiers, PSAT markers identify the normal operating point near saturation, and the amplifiers are operated with the power slightly backed-off approximately  0.03 to 0.1 dB. For TWT amplifiers, the saturation curve always "folds over" and produces a maximum power out.

For Solid State Power Amplifiers (SSPA), the saturation is not as well defined. A common reference is the Normal Operating Point, which is a power backed-off by 8 to 10 dB from the maximum power. In this case, the normal operating point marker replaces the Psat with the PNOP values.  Also, because the backoff is important, the backoff output and input powers are displayed (PBO Out), (PBO in) as well as gain at back off (PBO Gain).

Uses Markers 1, 2, and 3 to quickly identify output power saturation parameters of an amplifier.

Back-off is a point at which the output power is sufficiently lower than the saturated output power so that the device under test behaves in a more linear fashion.

Note: Valid ONLY for Power IN vs Power OUT measurements.  These markers can also be used on a CompOut trace with Compression Analysis mode in the Gain Compression Application.

To make a Power IN (X-axis) vs Power OUT (Y-axis) measurement:

1. Preset

2. Set Sweep Type: Power Sweep

3. Set Trace Meas to "B" Receiver

4. Connect DUT input to port 1

5. Connect DUT output to port 2

To create PSAT markers:

1. Press search, then [Search...]

2. From Search Type, select Power Saturation

3. For PMax Back-Off, enter the Y-axis (Power OUT) difference between the Max Power marker (3) and the Back-off marker (2).

4. Press Execute or check Tracking. Learn more.

This setting uses three markers to calculate and display 10 values.

The three markers:

• Marker 1: Linear gain; the first data point in the sweep.

• Marker 2: Specified output power Back-off from max power.

• Marker 3: Max Power output; usually the last data point.

The 10 displayed values:

• Comp. Not Found is displayed when the requested Back-off point is not found.

• When Discrete marker is NOT selected (the default setting), the three markers find an interpolated value between the two closest data points.

• When Discrete marker is selected (NOT interpolated), the three markers reside on the closest data points.

Uses Markers 1, 2, 3, and 4 to quickly identify Normal Operating Point parameters of an amplifier.

Back-off is a point at which the output power is sufficiently lower than the saturated output power so that the device under test behaves in a more linear fashion.

The power normal operating point is the output power where the input is offset from the back-off input power by the Pin Offset.

Note: Valid ONLY for Power IN vs Power OUT measurements.

These markers can also be used on a CompOut trace with Compression Analysis mode in the Gain Compression Application.

See Power Saturation to learn how to make a Power IN (X-axis) vs Power OUT (Y-axis) measurement.

To create PSAT markers:

1. Press search, then [Search...]

2. From Search Type, select Normal Operating Pt

3. For Back-Off, enter the Y-axis (Power OUT) difference between the Max Power marker (3) and the Back-off marker (2).

4. For Pin Offset, enter the X-axis (Power IN) difference between Back-off marker (2) and PNOP marker (4).

5. Press Execute or check Tracking. Learn more.

This setting uses four markers to calculate and display 12 values.

The four markers:

• Marker 1: Linear gain; the first data point in the sweep.

• Marker 2: Max Output Power MINUS the specified Output (Y-axis ) Back-off value in dB.

• Marker 3: Max Output Power; usually the last data point in the sweep.

• Marker 4: X-axis value of Back-off (Marker 2) plus the Pin Offset (X-axis) value in dB.

The 12 displayed values:

*Linear Gain (not shown): Marker 1 - Y-axis value MINUS X-axis value

• PNOP Not Found is displayed when the requested back-off level is not found.

• When Discrete marker is NOT selected (the default setting), the four markers each find an interpolated value between the two closest data points.

• When Discrete marker is selected (NOT interpolated), the four markers each reside on the closest data point.

How to change instrument settings using markers

Using front-panel
hardkey [softkey] buttons

Using Menus

1. Press Marker

2. then [Marker Function]

1. Click Marker/Analysis

2. then Marker Function

Marker Function dialog box help

Note: Marker Functions do not work with channels that are in CW or Segment Sweep mode.

Marker =>Start  Sets the start sweep setting to the value of the active marker.

Marker =>Stop  Sets the stop sweep setting to the value of the active marker.

Marker =>Center  Sets the center of the sweep to the value of the active marker.

Marker =>Ref Level  Sets the screen reference level to the value of the active marker.

Marker =>Delay  The phase slope at the active marker stimulus position is used to adjust the line length to the receiver input. This effectively flattens the phase trace around the active marker. Additional Electrical Delay  adjustments are required on devices without constant group delay over the measured frequency span. You can use this to measure the electrical length or deviation from linear phase.

This feature adds phase delay to a variation in phase versus frequency; therefore, it is only applicable for ratioed measurements. See Measurement Parameters.

Marker =>Span  Sets the sweep span to the span that is defined by the delta marker and the marker that it references. Unavailable if there is no delta marker.

Marker =>CW Freq  Sets the CW frequency to the frequency of the active marker. NOT available when the channel is in CW or Power Sweep. Use this function to first set the CW Frequency to a value that is known to be within the current calibrated range, THEN set Sweep Type to Power or CW.

Marker =>SA  This feature is supported in Standard, SMC or Swept IMD measurement classes (channels) ONLY. In this section, these are called NA channels.

With a marker residing on a trace in an NA channel, Marker=>SA creates a new SA channel in full frequency span. A marker is created on the trace at the same frequency as the NA channel trace. This is a quick way to see the frequency spectrum of the NA channel at a specific frequency. Learn more.

How to change marker display settings

Right-click on a marker readout, then click Marker Display or:

Using front-panel
hardkey [softkey] buttons

Using Menus

1. Press Marker

2. then [Properties]

3. then [Marker Display]

1. Click Marker/Analysis

2. then Marker

3. then Marker Display

Marker Display dialog box help

The following settings apply to readouts of ALL currently-displayed marker, bandwidth, and trace statistics.

These settings revert to their defaults on Preset but ARE stored with Instrument State and User Preset.

Marker Readout

Checked - Shows readout information.

Cleared - Shows NO readout information.

Large Readout

Checked - Shows the marker readout in large font size for easy reading. However, all readout lines may not be visible.

Cleared - Shows the marker readout in normal font size.

Readouts Per Trace

Choose the quantity of marker readouts to show in the window for each trace. Choose to display up to 10 readouts per trace, up to 20 readouts per window. When more markers are present than the specified quantity of readouts, the marker numbers for which readouts are displayed can change depending on the marker number that is active. Readouts Per Trace can be set independently for each window.

Symbol

Choose from the following marker symbols.

Line symbols are NOT used on Smith or Polar display formats.

Symbols can be set independently for each window.

Symbols Above Trace

Cleared - ONLY the active marker is displayed above the trace. Inactive markers are displayed below the trace.

Checked - ALL marker symbols are displayed above the trace. The active marker is always filled solid.

Decimal Places

Choose the marker readout resolution to display. These values also apply to the readouts that are displayed in the marker table. Decimal Places can be set independently for each window.

Stimulus (X-axis)  - Choose from 2 to 6 places after the decimal point. Default is 3.

Response (Y-axis) - choose from 1 to 4 places after the decimal point. Default is 2.

Readout Position

Choose where to place the marker readouts.  Marker readouts are right-justified on the specified X-axis and Y-axis position. The default position (10.0, 10.0) is the upper-right corner of the grid. Position (1.0,1.0) is the lower-left corner. Readout position can be set independently for each window.

Note:  Readout Position can also be changed using a mouse by left-clicking on the top readout and dragging to the new position.

Marker Colors  Starts the Display Colors dialog with only the marker colors available. Learn more.

How to view the Marker Table

Using front-panel
hardkey [softkey] buttons

Using Menus

1. Press Display

2. then [More]

3. then [Tables]

4. then [Marker Table]

1. Click Response

2. then Display

3. then Tables

4. then Marker Table