Author: James

The DSA 800 series of spectrum analysers are packed with features.
 
Spectrum analysers are similar to oscilloscopes.. except that they measure and display amplitude vs. frequency and not amplitude vs. time as a scope does.
 
Typical applications include Radio (Channel monitoring, demodulation of radio transmissions), Characterizing antennas, amplifiers, and filters, EMI/Interference testing, and RF education.
 
Here is a quick run through of the buttons and menu highlights:

• Frequency – Detector sweeps from a min to a  max value. Min 9kHz to 1.5GHz max
  • Center, Start, Stop
  • Peak to CF (Center frequency)

• Span – The frequency range scanned.
  • Full Span – fast way to get full frequency span
  • Zero span – Shows time vs amplitude at a fixed frequency range.. like an oscilloscope.
  • Zoom In/Out

• Amplitude
  • Autoscale
  • Adjust reference level (top of display)
  • Adjust input attenuation
  • Adjust scale, type, and units (Change units to dBuv)
  • RF Preamplifier standard
  • Correction factors (Antenna, Cable, Other, User) to compensate for losses and gains in setups
  • Input impedence (50Ohm and 75 Ohm) selection (only mathematically corrects display.. still need 50 to 75 Ohm adapter for physical match)

• Bandwidth/Detector – Configure measurement detector type and set bandwidth of measurement window at each frequency value.
  • RBW, VBW, and ratio (1,3,10 Resolution bandwidth settings standard.. low RBW of 100Hz)
  • Detector type – Positive peak most common. Quasi Peak available option.
  • Filter type – Gauss most common. EMI available option.

• Sweep/Trigger
  • Mode – Single or continuous.. can set external TTL trigger
  • Can select number of scans per trigger

• Trace
  • Select trace number, type
  • Averages per trace
  • Math functions
  • Pass Fail – Can create, edit, and store an Upper and Lower limit line. Can use this for creating pass fail limits for filters, AM/FM channels, and also EMC/EMI limit lines.

• Tracking Generator (Option)
  • Frequency scanning RF source with adjustable amplitude. The source frequency and bandwidth are identical to the input settings for the analyzer.
  • Can adjust for amplifier gain using TG level offset

• Measure
  • AMK (Total Power, Adjacent Channel Power, Channel Power, Occupied Bandwidth, Emission Bandwidth, Carrier to Noise Ratio, Harmonic Distortion, Third Order Intercept)
  • VSWR

• Demod
  • AM/FM

• Storage
  • 7 setups (includes data captured during save.. can be connected to preset key on the front panel as well as power-up)
  • 10 states (instrument configuration. Active data.. not stored from save as in setups)
  • Traces (CSV data to external USB memory stick)
  • Print BMP display image to USB.

• Marker
  • Markers indicate frequency and value of point on the trace. Available as Normal, Delta, Span Pair.
  • Can display as frequency, Period, or delta time
  • Can display a Marker table

• Marker function
  • Can configure and select a noise marker and frequency counter

• Peak – Quickly find peaks based on user defined amplitude value.
  • Selects peak value on trace. Can configure.
  • Peak table available.

• System
  • Language
  • Reset
    • Select power on state as well as configure the Preset button state
  • Calibrate
    • Adjust auto calibration
  • Adjust IO settings. DSA-815 has USB and LAN. A GPIB to USB adapter is available.
  • Display
    • Use to adjust display and trace brightness
    • Change function message
    • Enable/Disable display line
  • Work setting
    • Front Switch – If “Off”, unit will power on when mains power is present. No need to use the front power button.
    • Line mode – Allows you to save user States. You can connect these to the Preset button on the front panel
    • UserKey – You can use the User Key to gain fast access to a common setting or function.. simply enable the User Key, select the menu of choice (Measure > VSWR Enable) , and press User Key again. Now, User Key is linked to that menu item.

• Information – FW and HW revs
• Self Test
• Time/Date
• License – Check or install SW license options like VSWR or EMI
• TX1000 – This instrument can operate the Rigol TX1000 RF Evaluation board directly

 
 
Show:

• Low DANL.. <135 dBm.
  • From factory defaults:
  • Set frequency start to 1MHz. Set stop = 10MHz. Larger spans increase scan time considerably. Press FREQ > Start. Press Freq > Stop.
  • Set Resolution band width. Press BW/DET > RBW = 100Hz
  • Set Attenuator to 0dB. Press AMP > Input Atten = 0dB.
  • Enable RF Preamplifier. Press AMP > Down Arrow (page 2/2) > RF Preamp ON.
  • Change the amplitude scale. Press AMP > Scale/Div = 12db

Options:

• Software – Convenient field upgrade at any point. Just contact Rigol
  • Advanced Measurement kit – AMK
  • VSWR and available RF Coupler/Bridge (VB1020/30)
  • EMI toolkit featuring EMI filter, Quasi Peak Detector, and FCC RBW values
• Tracking Generator – Factory option. Must be selected at time of purchase.

The DSA815 features two pass fail limit lines, one upper and one lower. This document describes how to manually configure the upper limit line. 
•    In the control menu on the front pane, press Trace/P/F 
•    Select Pass/Fail
 
•    Switch On
•    Press Setup
 

•    Select Upper Limit
•    Select Edit
 

•    Select point 1. This is the start of the limit line. The X Axis must be non-zero. We selected 0Hz with the -20dBm amplitude for the initial low frequency portion of the limit line. 
NOTE: The Keypad is a convenient way to enter the values. Just type the numbers and select the desired units. 
 

•    Set point 2: X Axis 100MHz, Amplitude -20dBm, Connected = Yes

 
•    Set point 3: X Axis 100.000001MHz, Amplitude -10dBmm, Connected = Yes

 
•    Set point 4: X Axis 1.5GHz, Amplitude -10dBmm, Connected = Yes

 
•    In the control menu on the front pane, press Trace/P/F 
•    Select Pass/Fail
•    Select Setup 
•    Enable test by selecting Test ON
•    You can also enable Fail Stop and enable Beeper (page 2 of the setup menu)
•    You can store the limit lines internally or to an external USB stick by selecting storage, and set the filter type to Limit

A spectrum analyser with a tracking generator can be a useful piece of test gear. This application note covers making a simple loss measurement on a coaxial cable with BNC connectors.  
Required: 
–    Two N-type to BNC Adapters. Select adapters that convert N-type (in/out connectors on most spectrum analyzers) to the cable type you are testing. Also note that higher quality connectors (Silver plated, Beryllium Copper pins, etc..) equal better longevity and repeatability.
 

       Figure 1: N-type to BNC adapter
–    A short reference cable with terminations that match your adapters and cableunder-test.
–    An adapter to go between the reference cable and the cable-under-test. This experiment will use a BNC “barrel connector”. Note that higher quality connectors (Silver plated, Beryllium Copper pins, etc..) equal better longevity and repeatability.
 

          Figure 2: BNC barrel adapter
–    Alternately, you can use two adapters a short cable as a reference assembly to normalize the display before making cable measurements. This removes the need to have the cable-to-cable adapter.  
–    Spectrum analyser with Tracking Generator (TG)
Steps:
1)    Turn on Spec An and attach adapters to the tracking generator (TG) output and RF Input.
2)    Connect the reference cable to the TG out and RF In.
 

        Figure 3: Measuring reference cable
3)    Adjust Span of scan for frequency range of interest.
4)    Adjust TG output amplitude and spectrum analyser display to view the entire trace.
5)    Enable TG.
 

         Figure 4: Reference cable insertion loss before normalization.
6)    Normalize the reference insertion loss. This mathematically subtracts a reference signal (stored automatically) from the input signal. 
– With the Rigol DSA815 Press TG > NORMALIZE > STOR REF and then Enable   
Normalize
 

     Figure 5: Reference cable insertion loss after normalization.
7)    Disconnect the reference cable from the RF input.
8)    Place cable-to-cable adapter (BNC barrel or other) and connect to the cable to test.9) Connect the cable-under-test to test to RF input and enable the TG.
 

        Figure 6: Cable-under-test connected.
The screen displays the cable-under-test losses plus the error of the cable-to-cable adapter. 
 

           Figure 7: Cable-under-test loss.

Ultra Spectrum is a software package that enables remote control and data collection from Rigol DSA spectrum analyzers.
It is available for trial.
After the trial period has expired, you can purchase an activation license by contacting your local Rigol sales office.
Here are instructions for activating your license:

1. Download and install UltraSigma software (see Ultra Sigma instructions for more information)
2. Download and install Ultra Spectrum
3. Power on and connect your DSA via USB or Ethernet to the controlling PC
4. Run UltraSigma. This should bring up a screen as below.. with your DSA information.
5. Right-click on the resource, and select UltraSpectrum

      6.  You will get a prompt telling how many days left on your trial. Click Activate     


      7.  Enter the license code (Reg Code) and click OK
NOTE: License codes are linked to the instrument serial number. 

Some applications require adjusting the displayed amplitude to accurately account for losses in cables, gain in amplifiers/antennas, and other circuit elements. 
This note presents the steps to create, save, and recall correction factors on a DSA800 Series manually and programmatically.  
Create a Correction Factor (manually): 
1.    Press AMP > Down Arrow > Corrections 
  
 
2.    Select Antenna, Cable, Other, or User. These labels name temporary (volatile) storage of the correction value that you are entering.  
3.    Press Edit and use the key pad to enter the correction point and amplitude that cover the frequency range of interest. You can enter multiple points to create a correction profile for a particular antenna, cable, other, or user setting. 
 
4.    Press the back arrow to go back one menu.  
  

5.    Enable the Correction Table by pressing Corr Table ON. Verify the corrections are the proper values entered above. 
  
Figure 1: Correction Table enabled. In this example, there are two points set to show a -40dB correction from 0Hz to 1GHz.  
 
Store a Correction Factor: 
1.    Once you have created the correction profile for the element (antenna, cable, etc..) of choice, Press Storage  
HINTS: Change file type to CORRECTIONS to see correction files.  
•    Make sure you have used the Dir (directory) selection to choose either Local (:D) drive or the Mobile Disk (:E) USB drive.  
 
•    After you have selected a drive, change Browser to File to select and open file location or choose to overwrite an existing file. 
 
•    Put an indication of correction type in the file name. “A1” for antenna 1, “C1” for cabling setup 1, etc… This will make recalling the file easier in the future.  
 
 
Figure 2: Storage screen for the DSA. Note the Local drive is selected (Left hand side) as is the first corrections file shown. The filter type is set to Corrections. 
Correction files terminate in *.cbl. 
2.    Press Save and enter the name using the keypad.  
•    When you press a number, “3” for example, the letters under the number will appear. “3” has d, e, and f. Pressing the 3 again will advance the highlighted cursor from d to e. Press again, and it will go from e to f.  
 
•    You can select capitalize letters by pressing the “1” key 
 
•    Press “+/-” to toggle between Chinese, English Alphabet, and Numbers. 
 
3.    Press OK to save the file.  
NOTE: Correction values are stored under the label used to create them. For example, if you create an antenna correction factor and store it, it will be located under antenna when you go to recall it.  
     
Create a Correction factor (programmatically): 
You can also programmatically construct and activate correction files by using the following steps: 
 
1.    Build the correction table by sending the command: 
 
:CORR:CSET<n>:DATA<freq>, <rel_ampl>,{,<freq>, <rel_ampl>} 
 
Where <n> = Internal memory location (0-9) for the file 
<freq> = Frequency in Hz 
<rel_ampl>  = Correction value  
 
2.    To enable the correction table, send: 
 
:CORR:CSET<n> ON 
 
3.    To save the correction table, send: 
 
:MMEM:STOR:CORR <file_type>,<file_name> 
 
Where <file_type> = ANT|CABL|OTH|USER 
 
4.    Here is an example of creating a correction factor of -10dB from 1Hz to 1GHz and storing the file on a DSA815.  
 
The commands were sent using UltraSigma SCPI Panel Control. 
 
 
  
 You can enable the table manually by pressing AMPT > Down Arrow to page 2 > Corrections and selecting the proper correction file from memory  Recall a Correction factor: 
1. Press Storage  
NOTE: Insert USB drive if the correction factors were stored externally. 
1.    Select File Type filter to Corrections to show only corrections (*.cbl) files 
2.    Select the appropriate browser directory (DIR) to locate the file location 
3.    Change the browser to FILE and select the correction file of interest 
 
NOTE: The File Name will be highlighted when it is selected!  
If the file name is not highlighted, you will need to select it using Browser > File. 
4.    Press the down arrow to go to the Storage Menu page 2/3.  
5.    Press Recall to recall the file.  
6.    To confirm the correction, enable the corrections and corrections table 
•    Press AMPT > Down Arrow > Corrections 
•    Select the correction factor (antenna, cable, other, user)  
•    Enable correction factor by pressing Correction > On 
•    Enable correction table by pressing Corr Table > On 
NOTE: Correction values are stored under the label used to create them. For example, if you create an antenna correction factor and store it, it will be located under antenna when you go to recall it.

This document provides step-by-step instructions on using the Rigol DSA-800 series of Spectrum Analysers to measure the characteristics of an RF Bandpass filter.
NOTE: The DSA must have a Tracking Generator to effectively perform the following test.

Normalize the trace (Optional)

Many elements in an RF signal path can have nonlinear characteristics. In many cases, these nonlinear effects on your base measurements can be minimized by normalizing the instrument.
1.    Connect tracking generator output to RF input using the same cabling that you will be using to test your device. Any element, like an adapter, used during normalization should also be used during device measurement as any changes to the RF signal path could effect the accuracy of the measurement.
2.    Enable the tracking generator by pressing the TG button > TG On
3.    Store the reference trace by pressing the TG button > Normalize > Stor Ref
4.    Enable normalization by pressing the TG button > Normalize > Normalize On

Measure the filter
1.    Connect the tracking generator output to the filter input using the appropriate cabling and connectors.
2.    Connect the filter output to the instrument RF input.

3.    Set the tracking generator amplitude by pressing the TG button and the TG Amplitude. You can use the keypad or wheel to enter the correct value.

NOTE: If your instrument is equipped with a Preamplifier,    you can enable it to lower the displayed noise floor    by pressing the following sequence:
Amplitude button > Down Arrow > RF Preamp On
4.    Enable the Tracking generator by pressing the TG button > RF Source ON You can see the small bump in the figure below.

Figure 1: Before Auto.

5.    You can use the Auto button to center and zoom on the waveform. You can also use the Freq and Span buttons to manually manipulate the displayed data.

Figure 2: After Auto.
6.    You can now enable the Marker function to measure the bandwidth and attenuation or passband characteristics of the filter.
7.    Press Marker Fctn > N dB BW and set  the function to the amplitude of interest. In this example, we are measuring the 3dB Bandwidth of our filter.

This document provides step-by-step instructions on using the Rigol DSA-800 series of Spectrum Analysers to measure the characteristics of an RF Amplifier. 

In addition to the DSA-800 Spectrum Analyser, you will need an RF Source, cabling, and adapters. 
Measure the amplifier
1.    Connect the RF generator output to the RF input of the instrument using the appropriate cabling and connectors. 
NOTE: If your instrument is equipped with a Preamplifier,    you can enable it to lower the displayed noise floor    by pressing the following sequence:
             
   Press AMP button > Down Arrow > RF Preamp On
 
        Figure 1: Preamplifier off
 
        Figure 2: Preamplifier on
2.    You can use the Auto button to center and zoom on the waveform. You can also use the Freq and Span buttons to manually manipulate the displayed data.
 

• Another option to center the waveform is to press Freq button > Peak → CF. This will automatically align the center of the display with the peak of the trace.
3.    Freeze the unamplified trace by pressing Trace > Trace Type > Freeze. You can use the Marker button to create a marker. This can be used to find the peak frequency and amplitude of the displayed waveform.
4.    Disable the RF Generator output.
5.    Disconnect RF generator from the instrument RF Input and connect it to the Amplifier input. 
6.    Connect the Amplifier output to the instrument RF Input.
7.    Enable the RF generator.
8.    Enable a second trace to visualize the amplified signal by pressing the Trace button > Select Trace 2.
9.    Set the trace type to Clear/Write by pressing Trace > Type > Clear/Write.
10.You can use the Auto button or manually center the trace using the Freq, Span, and Amp buttons.
11.Readjust the amplitude scale by pressing Amp > Auto
12.You can enable an additional marker for the new trace by pressing Marker > Select the marker you would like to use 
13. Now, select the trace you want to mark by pressing Marker > Marker Trace 
> select trace of interest
• Be sure Normal is selected to enable the marker
 

14.You can also enable a marker table by pressing Marker > Down Arrow > Mkr Table ON. This allows a convenient way to compare markers and values between traces.
 

15.    Alternately, you can use the Trace Math function to create a Trace difference on the screen. 
16.    Enable Trace Math by pressing Trace > Trace Math
17.    Set Function to A-B
18.    Set A = T1
19.    Set B = T2
20.    Set Operate > On
21.Set Amplitude by pressing AMPL > Auto
NOTE:  New trace appears. This represents Trace 1 – Trace 2. 
22. Set Marker to Math Trace by pressing Marker > select Marker 3 
23.Set Marker Trace to Math by pressing Marker > Marker Trace > Math
 

• You can then move the marker to the smoothest portion of Trace 3.