Agilent
Acqiris Broadband High-Speed Digitizers
Using 89600 Vector Signal Analyzer Software
Application Note
Vector signal analysis using
Agilent Acqiris broadband digitizers.
Table of Contents
1 |
Overview |
3 |
|
|
1.1 |
89600 VSA software |
4 |
|
1.2 |
Required software revisions |
4 |
2 |
Install 89600 VSA Software |
5 |
|
3 |
Hardware Configuration |
6 |
|
|
3.1 |
I/O between computer and digitizer |
6 |
|
3.2 |
Anti-alias filters and alias exposure-free mode |
7 |
4 |
Operation |
8 |
|
|
4.1 |
Basic operation |
8 |
|
4.2 |
Sampling modes: full rate and user rate |
8 |
|
4.3 |
Differences from 89600 VSA operation |
12 |
5 |
Time and Frequency Span Operating Region |
12 |
|
|
5.1 |
The relationship of main time length, span, and sample rate |
12 |
|
5.2 |
Operating region curves for Agilent Acqiris digitizers |
13 |
|
5.3 |
Recording limits for Agilent Acqiris digitizers |
18 |
6 |
Out-of-Band Alias Exposure Zones |
19 |
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|
6.1 |
Setting up the alias exposure zone checker |
19 |
|
6.2 |
Using the alias exposure zone checker |
19 |
Appendix A |
23 |
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Appendix B |
25 |
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Appendix C |
26 |
||
For More Information |
28 |
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Related Literature List |
28 |
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2
1 Overview
This product note describes the characteristics, setup, and operation of a broadband vector signal analyzer (VSA) comprised of an Agilent Acqiris U1066A (DC440, DC438) or U1065A (DC282, DC252, DC222) high-speed digitizer and the 89600 vector signal analyzer software. By taking advantage of the layered architecture and extensive digital signal processing (DSP) routines of the 89600 VSA software, the digitizer becomes
a new “front end” data acquisition subsystem for the VSA. This hardware-software combination provides up to 2 GHz of analysis bandwidth depending on the digitizer used. See Table 1 for the supported digitizer models and the corresponding analysis bandwidths. Appendix A contains suggestions for ultra-wideband downconverters.
The 10and 12-bit, high sample rate analog-to-digital converter (ADC) in the Acqiris digitizers produces the large analysis bandwidths shown in Table 1. These bandwidths are capable of providing a spurious-free dynamic range greater than or equal to 40 dB for the U1065A and greater than or equal to 75 dB for the U1066A. This is sufficient for 1.5 to 2% error vector magnitude measurements in most cases. For spectrum measurements with higher dynamic range, a traditional spectrum analyzer should be used.
Table 1. Agilent Acqiris digitizers supported by 89600 VSA software
Model |
No of |
Max |
Frequency |
Default |
Optional |
|
channels |
sample rate |
range |
memory |
memory |
U1066A-001 (DC440) |
1 |
400 M |
dc – 100 MHz |
4 M |
8 M |
U1066A-001 (DC440) |
2 |
400 M |
dc – 100 MHz |
4 M |
8 M |
U1066A-001 (DC440) HF input |
1 |
420 M |
1 MHz – 300 MHz1 |
4 M |
8 M |
U1066A-001 (DC440) HF input |
2 |
420 M |
1 MHz – 300 MHz1 |
4 M |
8 M |
U1066A-002 (DC438) |
1 |
200 M |
dc – 78.125 MHz |
4 M |
8 M |
U1066A-002 (DC438) |
2 |
200 M |
dc – 78.125 MHz |
4 M |
8 M |
U1065A-001 (DC222) |
1 |
8 G |
dc – 2 GHz |
1 M |
128 M, 1 G |
U1065A-002 (DC252) |
1 |
8 G |
dc – 2 GHz |
1 M |
128 M, 1 G |
U1065A-002 (DC252) |
2 |
4 G |
dc – 1.5625 GHz |
512 k |
64 M, 512 M |
U1065A-004 (DC282) |
1 |
8 G |
dc – 2 GHz |
1 M |
128 M, 1 G |
U1065A-004 (DC282) |
2 |
4 G |
dc – 1.5625 GHz |
512 k |
64 M, 512 M |
1. Max span = 164 MHz
3
1.189600 VSA software
The 89600 vector signal analyzer software is the heart of the broadband VSA. This software provides flexible tools for analyzing and demodulating even the most advanced digital modulations, including those not defined by an established standard.
The VSA makes measurements on signals in the time and frequency domains using either the BB (baseband) or IF Zoom mode. In BB mode, the analysis frequency range is from 0 Hz to the stop frequency. In IF Zoom mode, the analysis frequency range is defined by center frequency and span. There is also an I+jQ mode for analyzing two baseband quadrature channels. Results for any mode can be displayed as magnitude
or phase, in I/Q and several other formats.
With the optional digital demodulator, Option 89600-AYA, modulation quality measurements in the form of error vector magnitude (EVM) can be made on digital wireless communications signals with bandwidths of hundreds of MHz. In addition, powerful diagnosis capabilities allow you to determine the exact impairments that cause a digitally modulated signal to fail quality standards.
The features of the digital demodulator include variable-block-size signal acquisition, pulse burst edge search, synch word search and a user-controllable adaptive equalizer.
User-selectable filter types include cosine (raised and square-root raised), Gaussian, lowpass, and user-defined. You can vary the filter alpha/BT shape factor. Supported modulation formats for both burst and continuous carriers include FSK, BPSK, QPSK, OQPSK, DQPSK, π/4DQPSK, 8PSK, QAM (16 to 1024), and MSK.
In addition, the 89600 software provides a signal record feature for later playback and analysis.
1.2 Required software revisions
Using the 89600 Series VSA software with Agilent Acqiris high-speed digitizers requires compatible software versions:
Table 2. Required software versions
Agilent Acqiris Software for |
AcqirisSoftware 3.2 |
Windows® |
(Driver AqDrv4.dll 4.13) or later |
For baseband operation: |
|
89600 VSA |
v8.00 or later |
Acqiris VSA Server |
1.0 or later |
For HF operation: |
|
89600 VSA |
v9.00 or later |
Acqiris VSA Server |
2.0 or later |
4
2Install 89600 VSA Software
The 89600 VSA software must be installed on a computer.
Installation for standard operation
Insert the Agilent Technologies 89600 Series Software CD-ROM in your standard PC and follow the instructions in the installation wizard. When the Installation Manager window opens, click Install 89600 Series Software. In the Hardware Support window, select Acqiris VSA Server. This will avoid installing unnecessary components on your computer. After the software and hardware support is installed, exit the Installation Manager window.
Installation for embedded operation
Operation of the 89600 Series software on an embedded Compact PCI computer is similar to operation on a standard PC. The instructions for standard operation can be followed here as well using a LAN or USB accessible CD drive.
Note: Before you can run the VSA with an Agilent Acqiris digitizer, make sure the Agilent Acqiris digitizer hardware and driver software are installed and configured as directed in the 89600 Series Installation and VXI Service Guide found on your Agilent Technologies 89600 Series Software CD or go to www.agilent.com/find/89600 then click on Technical Support > Manuals.
5
3Hardware Configuration
Connect the digitizer to the computer as shown in Figure 1a or 1b. There are two options for the connection, by remote computer or by embedded computer.
3.1 I/O between computer and digitizer
Operation of the 89600 Series software on an embedded Compact PCI computer is similar to operation on a standard PC. The instructions for standard operation can be followed here as well using a LAN or USB accessible CD drive.
Agilent Acqiris data acquisition system
Agilent Acqiris digitizer
1 2 3 4
Optional anti-alias LPFs
Interface
Input Ch 1 |
Input Ch 2 |
(Digitizer Ch 1) |
(Digitizer Ch 2) |
Figure 1a. Digitizers connected through CompactPCI to PCI interface
The digitizers can be connected through various interface types from a CompactPCI crate to either a desktop PC or a portable PC.
Agilent Acqiris data acquisition system
Agilent Acqiris digitizer
1 2 3 4
Optional anti-alias LPFs
Embedded computer
Input Ch 1 |
Input Ch 2 |
(Digitizer Ch 1) |
(Digitizer Ch 2) |
Figure 1b. Digitizers connected through embedded single board PC
Alternatively, the digitizers can be controlled by an embedded computer as shown in Figure 1b.
6
3.2 Anti-alias filters and alias exposure-free mode
The broadband VSA can be configured to be essentially alias-free by using the full rate sampling mode and installing an external lowpass filter on the digitizer input. Use BNC-f to SMA-m and SMA-f to BNC-m adapters to connect the filter’s SMA connectors to the digitizer in case the digitizer has BNC connectors.
Table 3. External lowpass filters
Digitizer model |
Cutoff frequency |
Filter part number |
|
U1066A-002 (DC438) |
90 MHz |
Mini-circuits BLP/SLP-90 |
|
U1066A-001 (DC440) |
100 MHz2 |
Mini-circuits1 |
BLP/SLP-100 |
U1065A (DC252 (2 ch), |
1650 MHz |
Mini-circuits1 |
SLP-1650 |
DC282 (2 ch)) |
|
|
|
U1065A (DC222, DC252 |
2000 MHz |
Mini-circuits1 |
SLP-2000 |
(1 ch), DC282 (1ch)) |
|
|
|
1.Mini-Circuits, Inc., 1-800-854-7949, www.minicircuits.com.
2.For the HF input a 300 MHz lowpass filter will avoid aliasing from signals above 300 MHz, but in-band and out-of-band aliasing is still possible since full rate mode is not supported with the HF input.
7
4 Operation
4.1 Basic operation
Operation of the broadband VSA is substantially the same as that of the 89600 VSA. See the following sections for some differences or special configurations. There is an online Tutorial and Getting Started Guide under the Help/Roadmap toolbar in the 89600 software.
4.2 Sampling modes: full rate and user rate
Full rate mode
When the Sample Mode is set to full rate using the Utilities/Hardware/ADC1 /Agilent Acqiris One Channel Digitizer/Configure/Sample Mode/Edit menu path for the U1065A-001 or Utilities/Hardware/ADC1 /Agilent Acqiris Two Channel Digitizer/Configure/Sample Mode/Edit menu path for all the other models, the digitizer sample rate is fixed at the maximum for each digitizer model according to Table 4.
Table 4. Sample rates of Acqiris digitizers in full rate mode
Digitizer model |
No. of channels |
Full sample rate |
U1066A-001 (DC440) |
1 |
400 M |
U1066A-001 (DC440) |
2 |
400 M |
U1066A-002 (DC438) |
1 |
200 M |
U1066A-002 (DC438) |
2 |
200 M |
U1065A-001 (DC222) |
1 |
8 G |
U1065A-002 (DC252) |
1 |
8 G |
U1065A-002 (DC252) |
2 |
4 G |
U1065A-004 (DC282) |
1 |
8 G |
U1065A-004 (DC282) |
2 |
4 G |
With the addition of the anti-alias lowpass filter described above, this mode is free of alias exposure zones. This means that no signal anywhere in the range of the VSA’s center frequency will alias upon the desired signal and corrupt the measurement.
There is a trade-off when using this mode. Although the digitizers have deep memories allowing long record lengths, if a longer Main Time (or Result Length for digital demodulation) is needed for more resolution in the frequency domain a different sample mode may be required. Go to the Configure menu, click on Sample Mode/Edit and select User Rate from the drop-down menu. The Main Time limit for any sample rate is shown in the operating region curves that appear in Appendix C.
NOTE: Any limitation to Main Time (or Result Length) will be indicated by the inability of the software to increase the Main Time or decrease RBW when Number of Frequency Points is increased.
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