This section explains the methods to improve measurement throughput.
Other topics about Optimizing Measurements
The E5071C provides the two sweep modes: Stepped Mode and Swept Mode.
|
Mode |
Stepped |
Swept |
|
Measurement Reliability |
High |
Low |
|
Sweep Time |
Long |
Short |
|
Restrictions on measurement |
No Particular restriction |
DUT with long electrical delay cannot be measured correctly. |
Press Sweep Setup key.
Click Sweep Mode.
Select Stepped or Swept for your appropriate sweep mode.
In the stepped mode, the frequency is changed stepwise and sampling is performed at a fixed frequency for each measurement point. On the other hand, in the swept mode, sampling is performed with the frequency always swept for each measurement point.
In the stepped mode, a certain time should be allowed until the frequency becomes stable at each measurement point, since the frequency is changed stepwise. Therefore, the sweep time in the swept mode is generally shorter than that in the stepped mode. However, if the measurement point interval is extremely large, the sweep to the next measurement point frequency cannot be completed within the sampling time due to the limitations of the instrument's frequency sweep speed. This causes a certain waiting time until the start of measurement of the next measurement point, and thus in this case the swept mode actually has a longer sweep time.
Although there is some difference depending on the IF bandwidth setting, when the measurement point interval is approximately 30 MHz or less, the sweep time in the swept mode is shorter than that in the stepped mode.
When you use the swept mode, you should confirm that there is no measurement-related problem before performing the actual measurement.
The swept mode has the following disadvantages.
DUTs with long electrical delay time cannot be measured correctly. For more information, refer to Notes for measuring DUTs with long electrical delay time
Trace noise may increase compared to the stepped mode because sampling is performed while sweeping the frequency.
The specifications are not guaranteed
When sweeping the frequency of a signal applied to the DUT (F), there is a frequency difference between the input side and output side of the DUT due to the delay time that occurs in the DUT (Delta T). This frequency difference (Delta F) becomes larger as the electrical delay time of the DUT becomes longer and the frequency sweep speed becomes faster, as shown in the following equation.
When measuring a DUT with long electrical delay time, if you perform measurement (sampling) while sweeping the measurement signal as in the swept mode, a measurement error occurs due to the difference between the frequency outputted from the source port and the frequency actually measured at the receiver port.
Therefore, when measuring a DUT with a long electrical delay time, generally use the stepped mode to prevent the measurement error described above. However, if you need to shorten the sweep time, evaluate the measurement error as described below to determine the sweep mode that should be used.
If you are using the E5071C with HDD revision CFxxx or CNxxx, turning OFF the updating of information displayed on the LCD screen eliminates the processing time required to update displays within the analyzer, improving measurement throughput. If it is not necessary to check displayed information during measurements, turning OFF real-time updating is an effective means of improving throughput.
The updating of information displayed on the LCD screen can be switched using the following procedure:
Press Display key.
Click Update to switch the updating of displayed information on the LCD screen ON/OFF.
When the LCD screen update is turned OFF, Update Off appears on Instrument Status Bar.
For HDD revision CHxxxx, turning OFF the information update on the LCD screen does not contribute to any improvement in measurement throughput.
The E5071C executes Port Characteristics Correction in the data processing flow shown in Data Processing Flowchart, by using the system calibration data set at the factory. This system error correction process is not required if the user performs proper calibration by using the Cal key and the softkeys that subsequently appear, which automatically turns on error correction.
By turning OFF system error correction, you can reduce the data processing time needed during measurement and thus improve measurement throughput.
When you turn ON/OFF system error correction, all calibration data set by user calibration is deleted.
Press System key.
Click Service Menu > System Correction.
Click OK to turn ON/OFF system error correction.
The E5071C sets proper RF ranges of all test ports prior to every sweep. When you turn RF Range Fixed mode ON, the E5071C fixes RF ranges of all test ports so that it reduces 2 ms per each sweep from setting time before the measurement. This reduction will not be displayed in Sweep Time, though you can verify it by monitoring Handler I/O signals or *OPC? query.
This setting is available at the firmware revision A.11.00 or higher.
To turn ON/OFF the RF ranging, follow the below procedure:
Press System key.
Click Service Menu > RF Range Fixed.
Toggle between the ON and OFF selection. When ON is selected,setting time is shortened by 2ms. This setting is applied to all the channels.
This function does not reduce setting time when you use the E5091A/92A with the E5071C, though it is possible to turn ON/OFF this function.
If the RF Range Fixed mode status is changed after a calibration is performed, the calibration data will be useless and C! will be displayed. See Checking Calibration Status for details. In this case, it is strongly recommended to perform a calibration again.
Turning ON this function may degrade some analog performances such as dynamic range. See the data sheet for detail.