This section describes the following functions that can be used to improve phase measurement accuracy.
Other topics about Optimizing Measurements
Electrical Delay is a function that adds or removes a pseudo-lossless transmission line with a variable length corresponding to the receiver input. Using this function enables you to improve the resolution in phase measurement and thereby measure deviation from the linear phase. You can specify the electrical delay trace by trace. Depending on the media type, the calculation method of the electrical delay, which is required to correct the phase delay, differs.
Press Channel Next/Channel Prev keys and Trace Next/Trace prev keys to activate the phase trace for which you want to specify the electrical delay.
Press Scale key.
Click Electrical Delay.
Change the electrical delay (in seconds) in the data entry area.
Click Media, and select a media type for calculating the electrical delay. If the electrical delay is 0 second, the calculation result is always the same regardless of media type.
|
Softkey |
Function |
|
Coaxial |
Selects Coaxial as the media type. |
|
Waveguide |
Selects Waveguide as the media type. |
If you have selected Waveguide as the media type, click Cutoff Frequecy, and specify a cutoff frequency.
The cutoff frequency is available only when the media type is Waveguide.
For how to determine the deviation from a linear phase, see Measuring the Deviation from a Linear Phase.
Press Channel Next/Channel Prev keys and Trace Next/Trace prev keys to activate the trace for which you want to set the electrical delay.
Place the active marker in an appropriate position.
Press Maker Fctn.
Click Marker -> Delay to set the electrical delay to the group delay value at the position of the active marker (a value smoothed with the aperture of 20% regardless of the smoothing setting).
Phase offset is a function used to add or subtract a predetermined value relative to the frequency to and from the trace. Using this function enables you to simulate the phase offset occurring as a result of, say, adding a cable.
The phase offset can be specified from - 360° to +360° .
Press Channel Next/Channel Prev keys and Trace Next/Trace prev keys to activate the trace for which you want to specify the phase offset.
Press Scale key.
Click Phase Offset, then enter the phase offset (° ) in the data entry area.
The velocity factor is the ratio of the propagation velocity of a signal in a coaxial cable to the propagation velocity of that signal in free space. The velocity factor for a common cable is about 0.66. The propagation velocity depends on the dielectric constant (εr) of the dielectric substance the cable.
By specifying the velocity factor, you can match the equivalent length (in meters) appearing in the data entry area to the actual physical length when using the Electrical Delay or Setting port extensions to specify the electrical delay (in seconds).
You can define the velocity factor channel by channel.
Press Channel Next/Channel Prev keys to activate the channel for which you want to specify the velocity factor.
Press Cal key.
Click Velocity Factor, then the velocity factor in the data entry area.
Port Extension is a function for moving the calibration reference plane by specifying the electrical delay. This function is useful, for example, when you cannot directly perform calibration at the DUT terminal because the DUT is inside the test fixture. In such a case, this function enables you to first perform calibration at the test fixture terminal and then move the calibration plane to the DUT terminal by extending the port.
Port extension corrects the electrical delay of each test port (phase shift) only. It cannot remove errors caused by the loss in and incorrect matching of cables, adapters, or test fixtures.
You can define port extension channel by channel. Setting port extension for one particular channel does not affect other channels.
Auto Port Extension does not supports waveguide port extension.
Press Channel Next/Channel Prev keys to activate the channel for which you want to set port extension.
Press Cal key.
Click Port Extensions, and then Select Extension Port 1/2/3/4.
Specify Loss values by clicking Loss.
Follow the steps below to set coaxial or waveguide delay:
Press Channel Next/Channel Prev keys to activate the channel for which you want to set port extension.
Press Cal key.
Click Port Extensions.
|
Softkey |
Function |
|
Auto Port Extension |
Sets the Auto Port Extension |
|
Extension Port 1 |
Sets port extension (in seconds) for test port 1. |
|
Extension Port 2 |
Sets port extension (in seconds) for test port 2. |
|
Extension Port 3 |
Sets port extension (in seconds) for test port 3. |
|
Extension Port 4 |
Sets port extension (in seconds) for test port 4. |
Click Extension Port n where n can be from 1 to 4.
Click Waveguide to set delay in sec.
Click Cutoff Frequency to set cut off frequency of selected port.
Click Coax. Extension to set the coaxial extension in sec.
If you want to use waveguide port extension, then setting of coaxial delay is not necessary. If only waveguide measurement is needed, coaxial delay should be set to zero. Coaxial extension value should be set while measuring adapters between coaxial and waveguide.
Waveguide delay and Cut off frequency can be set using the following commands:
SCPI.SENSe(Ch).CORRection.EXTension.PORT(Pt).WAVeguide.TIME
SCPI.SENSe(Ch).CORRection.EXTension.PORT(Pt).WAVeguide.CUToff
System Z0 should be changed to 1 ohm before calibration when using waveguide calibration kit and measuring waveguide devices.
Some calibration kits such as the waveguide calibration kit have operational frequency range defined by Minimum and Maximum frequency. When the E5071C stimulus setting is out of the operational frequency range, you cannot click Done key or finish the calibration by remote control. In this case, use a calibration kit that has proper frequency range, or change the E5071C stimulus setting to proper range that the calibration kit can cover. Refer to the calibration kit manual or definition in the E5071C with Cal > Modify Cal Kit > Define STDs for the Maximum & Minimum frequency of the calibration kit.
In addition to port extension, you can set loss values for each port. By correcting loss due to port extension, more accurate measurement results are obtained.
There are two types of loss value settings: loss values at two frequency points for a specified port, and a DC loss value. You can make these settings at the same time for each port.
You can set loss values channel by channel. Setting loss values for one particular channel does not affect other channels.
Press Channel Next/Channel Prev keys to activate the channel for which you want to set loss values.
Press Cal key.
Click Port Extensions.
Click Extension Port n where n can be from 1 to 4.
Click Loss to set a loss value.
Click Loss1 [OFF] to toggle to Loss1 [ON] (enabled), and enter a loss value (Loss1) and a frequency (Freq1).
If you want to set loss at two frequency points, press Loss2 [OFF] to toggle to Loss [ON] (enabled), and enter a loss value (Loss2) and a frequency (Freq2).
If you want to set loss values for other ports, repeat steps 4 to 6.
Expression to calculate loss using Loss 1:
Expression to calculate loss using Loss 1 and Loss 2:
When you specify two frequency points, set the lower frequency to Loss1, and the higher one to Loss2.
Press Channel Next/Channel Prev keys to activate the channel for which you want to set DC loss values.
Press Cal key.
Click Port Extensions > Loss.
Click Select Port to select the port for which you want to set a DC loss value.
Click Loss at DC, then enter a DC loss value.
If you want to set a DC loss value for other ports, repeat steps 4 to 5.
Press Channel Next/Channel Prev keys to activate the channel for which you want to enable port extension.
Press Cal key.
Click Port Extensions.
Turn on Extensions.
The auto port extension function measures port extension and loss values for each port using the OPEN/SHORT standard connected to the port, automatically calculates them, and set them.
|
Softkey |
Function |
|
|
Auto Port Extension |
Select Ports |
Sets the Ports (1 to 4) |
|
Measure OPEN |
Performs a OPEN measurement |
|
|
Measure SHORT |
Performs a Short measurement |
|
|
Method |
Sets the Span |
|
|
Include Loss |
Sets Loss ON/OFF |
|
|
Adjust Mismatch |
Sets Adjust Mismatch ON/OFF |
|
When the auto port extension function is completed, the port extensions and loss values are updated to the calculated values.
You can use both open and short measurement values in the auto port extension function. Note that in this case, the average value of the calculation results is used for updating.
You can set the auto port extension function channel by channel. Setting the auto port extension function for one particular channel does not affect other channels.
When the sweep type is power sweep or the frequency offset function is ON, the auto port extension is not available.
Auto Port Extension does not supports waveguide port extension.
Select the port(s) for which you want to use the auto port extension function.
Press Channel Next/Channel Prev keys to activate the channel for which you want to set auto port extension.
Press Cal key.
Click Port Extensions > Auto Port Extension > Select Ports to select the port(s) for which you want to use the auto port extension function.
Set the frequency points with which you want to calculate a loss value.
Press Channel Next/Channel Prev keys to activate the channel to set auto port extension.
Press Cal key.
Click Port Extensions > Auto Port Extension > Select Ports > Method to set the frequencies used for calculation.
|
Softkey |
Function |
|
Current Span |
Executed using the frequency range set currently. |
|
Active Marker |
Executed using the frequency at the active marker. In this case, the result is applied to Loss1. Loss2 is ignored. |
|
User Span |
Executed using a start value and a stop value you set. |
If you have selected User Span, use User Span Start and User Span Stop to set a start value and a stop value.
For Current Span and User Span, a frequency point at 1/4 of the frequency range is set to Freq1; a frequency point at 3/4 of the frequency range is set to Freq2.
If the setting is not made before starting OPEN/SHORT standard measurement, it does not affect the calculation result.
Specify whether you want to include a loss value in the calculation result.
Press Channel Next/Channel Prev keys to activate the channel for which you want to set auto port extension.
Press Cal key.
Click Port Extensions > Auto Port Extension > Select Ports > Include Loss to turn it on.
If the setting is not made before starting the measurement of the OPEN/SHORT standard, it does not affect the calculation result.
Specify whether you want to include a DC loss value in the calculation result.
Press Channel Next/Channel Prev keys to activate the channel for which you want to set auto port extension.
Press Cal key.
Click Port Extensions > Auto Port Extension > Adjust Mismatch to turn it on.
If the setting is not made before starting the measurement of the OPEN/SHORT standard, it does not affect the calculation result.
Calculate port extensions and loss values based on the calculation results using the OPEN/SHORT standard.
Press Channel Next/Channel Prev keys to activate the channel for which you want to want to set auto port extension.
Press Cal key.
Click Port Extensions > Auto Port Extension.
If you use the OPEN standard, click Measure OPEN, and select the port(s) for which you want to execute measurement. Execution is restricted to ports selected in Selecting a port(s)
If you use the SHORT standard, click Measure SHORT, and select the port(s) for which you want to execute measurement. Execution is restricted to ports selected in Selecting a port(s).
If a port extension value or loss value has been set, the value is updated to the calculated result.
If you execute both open measurement and short measurement, the average of the calculation results is reflected to the port extension and loss value.
When you exit from the softkey menu in the same level after open/short measurement, the measurement results are deleted. Note that you can use a GPIB command.
Port extension and loss values that have been calculated are not cleared.