Applications - NI PXIe-5665 High-Performance Vector Signal Analyzer

Publish Date: Jul 29, 2011 | 6 Ratings | 2.17 out of 5 |  PDF

Overview

The NI PXIe-5665 is a high-performance vector signal analyzer capable of a frequency range from 20 Hz to 14 GHz. It features a phase noise of -129 dBc/Hz at a 10 kHz offset and an average noise floor of -165 dBm/Hz. The frequency range, high dynamic range, and accuracy of this instrument make it ideal for the detection of small signals at high frequencies.

Table of Contents

  1. Harmonic Testing Using RF List Mode
  2. Radar Testing
  3. Cellular/Semiconductor Testing
  4. Signal Intelligence and Spectrum Monitoring
  5. Summary

1. Harmonic Testing Using RF List Mode

You can use the NI PXIe-5665 for harmonic and spur testing, which is common in characterizing power amplifiers and other radio frequency integrated circuits (RFICs) used in cell phones. Even at a range of 12 GHz to 14 GHz, the NI PXIe-5665 features an average noise floor of -142 dBm/Hz and an amplitude accuracy of ±0.25 dB, making it ideal for testing and detecting small signals at high frequencies.

Figure 1. 14 GHz Spectrum With Spurs and Harmonics

You can also use RF list mode on the NI PXIe-5665 to quickly jump between frequencies, thus greatly decreasing sweep times. With RF list mode, you can predefine a list of frequencies or reference levels among other parameters, which get converted to microcode that eliminates time-intensive software calls from the instrument to the PC and vice versa.

 

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2. Radar Testing

Figure 2. Radar Types

Radar types are defined by the information gathered and the technique used in an application.

Imaging radars gather information in at least two dimensions to form a map-like picture of the region covered by the radar. Imaging radars have been used to map the Earth and celestial objects as well as to categorize targets for military systems.

Nonimaging radars gather information in one dimension. Typical implementations of a nonimaging radar system are speed gauges and radar altimeters.

Another way to classify radar is by primary and secondary. A primary radar transmits RF or microwave signals and processes the reflections from the target. A secondary radar receives a transmitted response from the target. In this case, the target must have a transponder (transmitting responder) on board, and this transponder responds to interrogation by transmitting a coded reply signal. This response can contain much more information than a primary radar unit is able to acquire. Nonimaging secondary radar applications include immobilizer systems in some recent private cars.

 

IEEE Std. 521, 1984

 

EU-NATO-US

 

Modern Applications of Radar

Radar letter designation

Frequency range

Frequency range

ECM frequency designation

HF

3 to 30 MHz

to 250 MHz

A

Experimental navigational aids; over-the-horizon and surface scanning; space surveillance

VHF

30 to 300 MHz

250 to 500 MHz

B

Military early warning and surveillance; wind scanners

UHF

300 to 1000 MHz

500 MHz to

1 GHz

C

Shipboard long-range surveillance; space research; test range instrumentation; wind profiling

L

1 to 2 GHz

1 to 2 GHz

D

Air traffic control; military early warning; synthetic aperture radar; ground battlefield sensors; space-based radar

S

2 to 4 GHz

2 to 3 GHz

E

Planetary exploration; air traffic control; marine navigation; weather

   

3 to 4 GHz

F

Air surveillance and tracking; test range instrumentation

C

4 to 8 GHz

4 to 6 GHz

G

Radar altimeters; weather radar; airport terminal Doppler weather radar (TDWR, wind shear); military surveillance and air defense

6 to 8 GHz

H

Air and ship surveillance and navigation; fire control; test range instrumentation; SAR; scatterometer

X

8 to 12 GHz

8 to 10 GHz

I

Air and ship surveillance and navigation; airborne weather; police speed radar; radar altimeters; air navigation aids; fire control; test range instrumentation

10 to 20 GHz

J

Air and ship surveillance and navigation; airborne weather; police speed radar; radar altimeters; air navigation aids; fire control; test range instrumentation

Ku

12 to 18 GHz

K

18 to 27 GHz

20 to 40 GHz

K

Airborne navigation; surface mapping, police speed radar; terrain following radar; test range instrumentation; atmospheric and oceanographic research; scatterometers

Ka

27 to 40 GHz

V

40 to 75 GHz

40 to 60 GHz

L

60 to 100 GHz

M

Aircraft fire control; radar beacons; missile autonomous guidance; weather; specialized imaging radars

W

75 to 110 GHz

mm

110 to 300 GHz

Table 1. Radar Applications

The NI PXIe-5665 features a frequency range of 20 Hz to 14 GHz, so you can test up to the X and Ku bands. With the NI PXIe-5665 software-defined approach, you can process received data on a host PC. For real-time analysis, you can use an NI FlexRIO instrument for processing on an open field-programmable gate array (FPGA).

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3. Cellular/Semiconductor Testing

New cellular and data standards are emerging at a fast pace, and test engineers have had to continually adapt to these new standards. With the software-defined approach to instruments on NI RF instruments, you can use one analyzer/generator with a variety of software toolkits from NI such as WCDMA, LTE, GPS, and Bluetooth among others. You can even adopt standards that are in their early stages because you are using the same hardware and changing only a software layer.

Figure 3. An Upper ACLR of -81.7 dBc

With best-in-class phase noise, dynamic range, and linearity, you can make low ACLR measurements on the NI PXIe-5665.

Figure 3 shows an upper ACLR of -81.7 dBc. You can also use the NI PXIe-5665 to make EVM measurements as low as .15 percent RMS on LTE.

 

Figure 4. You can also use the NI PXIe-5665 to make EVM measurements as low as .15 percent RMS on LTE.

Noise Correction – The NI PXIe-5665 also uses noise correction to reduce the noise floor of the instrument. To achieve this, the RF input is disconnected internally and connected to a 50 Ω impedance. The floor of the instrument is measured with this setup and stored in cache. The RF input is then connected again and the real measurement is made. The noise floor measurement (stored in cache) is then subtracted from the real measurement, thus lowering the noise floor by at least 5 dB to 6 dB. Figure 5 shows the effect of noise correction on a WCDMA signal.

Figure 5. The Effect of Noise Correction on a WCDMA Signal

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4. Signal Intelligence and Spectrum Monitoring

For applications such as signal intelligence and spectrum monitoring, you need to acquire wide ranges of frequencies and analyze them in a short time. In addition, the instrument must be able to tune to frequencies quickly and process the data as soon as possible. With the peer-to-peer streaming capabilities of the PXI platform, you can stream the entire bandwidth at about 800 MB/s to an open FPGA for processing.

Peer-to-Peer Data Streaming – With NI peer-to-peer data streaming technology, you can continuously transfer data to and from PXI Express NI FlexRIO FPGA modules at rates greater than 800 MB/s with minimal latency. High-performance data switches on NI PXI Express chassis offer high-bandwidth communication, while routing data from one module directly to another (without transferring data through the host controller) minimizes the latency of the transfer. Peer-to-peer transfers are supported between multiple PXI Express NI FlexRIO FPGA modules and between select NI PXI Express digitizers and PXI Express NI FlexRIO FPGA modules. Figure 6 depicts a peer-to-peer system with an NI PXIe-5122 digitizer and two NI PXIe-7965R NI FlexRIO FPGA modules for distributed serial data processing.

 

Figure 6. Peer-to-Peer System With an NI PXIe-5122 Digitizer and Two NI PXIe-7965R NI FlexRIO FPGA Modules for Distributed Serial Data Processing

 

IF filter bank – The NI PXIe-5665 also features multiple paths for IF filters, a 300 kHz narrow band path, a 5 MHz path, and a through path with a nominal bandwidth of 50 MHz.

Preselector – The NI PXIe-5665 also features a YIG tuned filter (YTF) at above 3.6 GHz. The YTF has a 45 MHz bandwidth and provides image rejection at higher frequencies. This filter is ideal for spectrum monitoring and signal intelligence applications for which wide bandwidth spectrums are acquired. Figure 7 shows the effect of the YTF on and off.  

Figure 7. The Effect of the YTF On and Off

 

For applications such as signal intelligence and spectrum monitoring, the instrument needs to tune between frequencies as fast as possible. The NI PXIe-5665 has two options on the oscillator that is used to tune the frequencies: a fast mode and a normal mode. 

 

Mode

Tuning Speed

(1 GHz Step)

Frequency Accuracy

Phase Noise

(10 KHz offset)

Normal 9.3 ms 0.1 ppm -134 dBc/Hz
Fast 2.3 ms 1 ppm -130 dBc/Hz

Table 2. The NI PXIe-5665 has two options on the oscillator that is used to tune the frequencies: a fast mode and a normal mode. 

 

The normal mode takes 9.3 ms for a 1 GHz step whereas the fast mode takes 2.3 ms. However, the normal mode does have better frequency accuracy and phase noise.

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5. Summary

The NI PXIe-5665 features a frequency range and best-in-class linearity, dynamic range, and noise floor that can make your cellular, radar, and spectrum monitoring tests and applications faster by at least 15X at a lower cost. The software-defined architecture of the NI PXIe-5665 offers you flexibility for a variety of applications requiring multiple standards.

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