R. A. Wood Associates has been awarded a contract from Naval Surface Warfare Center (NSWC), Crane Division. The contract involves designing and delivering an automated test rack consisting of:
We are fortunate to be able to work with Viewpoint Systems on this contract.
This contract was won on a competitive bid, and our solution was selected out of many other submissions. We are very excited about the opportunity to work with NSWC Crane Division!
Hello Fellow Test Engineers and Managers:
We have a software program, called RFSpecTest, which has many built-in computer automated RF/microwave tests already developed. We've just created a demonstration version that can be downloaded and evaluated. More information is available from our software information page. Download the demo, and try out the tests and interfaces available. We also have some sample measurement files you can load into the program. Give it a try and let us know what you think!Thanks! Bob Wood
|We designed and developed a Computer Automated RF Test Station for one of our customers. The Computer Automated RF Test Station is capable of testing 7 different RF and RF/digital modules, but is flexible enough to test many possible RF modules. The Test Stations were built and tested at R. A. Wood Associates. Computer automated test software was also developed to test the 7 different modules using LabVIEW. RFSpecTest was used in a "scripted" mode to perform all RF tests. More information about the Computer Automated RF Test Station is available at this link.|
We are very close to releasing a "stable" beta version of our RF Path Analysis Toolkit environment. This will allow engineers to create RF path (cascade) analysis spreadsheets to analyze their RF and microwave designs. The program uses library files, RF path files, and template spreadsheets within a LabVIEW user interface to create an full RF path analysis environment. Please stop by again soon to download and try out this new software package.
Some people had trouble installing PathLossSolver on their computer. We've added a revised version (1.1h) of the program that should be easier to install. Go to our software download page for the latest updates. Thanks for your patience!
We've added a few improvements to SpurFinder Version 3.1g. Some of the improvements are:
For some Windows XP users, the fonts used in our software programs were not available in Windows XP, causing the front panel fonts to be substituted with other fonts. This caused some displays to become overcrowded. The newer versions use a font that is available in all Windows versions. You can download the newer versions if you have had trouble with the front panel display fonts. Go to our software download page for the latest updates
R. A. Wood Associates demonstrated our RFSpecTest software product at MTT Symposium in Philadelphia, PA during June 10-12, 2003. See our Press Release for more info.
We've updated our software products to improve the payment and registration process. You can now pay for registration directly through PayPal, E-mail, or using a WWW form. This feature is built in to the software programs. The User Name and Registration Key are sent to us electronically. After payment is confirmed, we will send you a Registration Number electronically via E-mail. This should make the whole payment and registration process smoother and simpler.
R. A. Wood Associates introduced their latest computer automated RF test software suite, RFSpecTest, at National Instruments (NI) Week, August 13-16. See Press release. The test software suite is centered around NI's latest RF product, the NI 5660 Spectrum Analyzer. Automated testing for gain, two tone intermodulation products, gain compression, relative measurements, and others was demonstrated for amplifiers, mixers, switches, filters, attenuators, RF integrated circuits and more. Thanks to all who stopped by to see our new product! A picture of our booth and computer automated test setup at NI Week. For an overview of the of RFSpecTest, select this link (1.7 MB pdf file).
Version 2.1e adds new features, including:
Version 3.1e adds new features, including:
Upgrade and Repair Services
We have developed a computer automated Metal Tester for testing metals using thermo-electric measurements from an Acromag meter, a PC A/D converter board, and LabVIEW software. For more information, go to this page.
Computer Automated Test System for LDMOS Wireless RF Power Amplifiers
A software program was developed using LabVIEW, a graphical programming language from National Instruments. The program runs on a PC and is connected to an Acromag Metal Tester using a PC Data Acquisition board. The program compares the readings gathered from the Metal Tester to readings in a database for various alloys. The program then gave a readout of what metal alloy most closely coincided with the metal being tested. The program also provided probability levels (T-Test) to show confidences against the various other possible alloys in the database. The MetalTest System is currently being used to recycle aircraft engine machining scrap and is helping the company earn hundreds of thousands of dollars in metal reclamation sales.
Engineering Consulting Examples: IF Receiver/Digitizer
Software was developed to retrieve the binary data from a IF Receiver/Digitizer board. The board design utilized a 10 MHz A/D converter to sample the IF signal. A Logic Analyzer attached to the board captured the digital data from the IF Receiver/Digitizer board. The computer used an IEEE-488 interface to connect to the Logic Analyzer and retrieve the values. After the binary data was retrieved, converted, and stored in an array, the data could be graphed and analyzed. The arrays were converted to a series of voltage values of the incoming signal. The voltages were plotted and then recorded. The data was then used in signal frequency and noise analysis. The Fast Fourier Tranform was used to determine the spectral content of the sampled signals. The FFT of the digital signal could then be compared to the Power Spectrum Analyzer data of the analog signal. The software was developed using National Instruments LabVIEW graphical programming language. The measured data could be stored to a data file to record that particular test.
Two Tone Third Order Output Intercept Point Measurements
This LabVIEW panel shows the results of computer automated Two-Tone Third Order Output Intercept Point measurements for a PCS band RF amplifier. Measurements were performed using two programmable signal generators and a spectrum analyzer. A power meter was used to calibrate the input and output cables and connectors, and the spectrum analyzer amplitude readings. This panel design is tailored toward an "engineering evaluation" environment, instead of a "production test" environment.
1 dB Output Gain Compression Point Measurements
This LabVIEW panel shows the results of a computer automated 1 dB Output Gain Compression Point measurements for a PCS band RF amplifier. Measurements were performed using a programmable signal generator and a spectrum analyzer. A power meter was used to calibrate the input and output cables and connectors, and the spectrum analyzer amplitude readings. This panel design is tailored toward an "engineering evaluation" environment, instead of a "production test" environment. This is just one example of the types of automated RF measurements that can be performed using LabVIEW.
LabVIEW Example - Computer Automated Noise Figure Measurements
This LabVIEW panel shows the results of computer automated Noise Figure measurements for a PCS band RF amplifier. Measurements were performed using a HP-8970B Noise Figure Meter. This panel design is tailored toward an "engineering evaluation" environment, compared to a "production test" environment. This is just one example of the types of automated RF measurements that can be performed using LabVIEW.
Cryogenic Cooled RF Amplifier Development for PCS Application
Software Controlled Laser Power Meter Interface
LabVIEW Example - Spectrum Analyzer Instrument Driver
This LabVIEW panel shows an software controlled instrument driver that is utilized for HP Spectrum Analyzers. The software has been used on HP-8566B and HP-8593E Series Spectrum Analyzers. All front panel controls are translated to GPIB commands to control the equipment over a GPIB interface. The output readings are Marker Frequency and Marker Amplitude. Various options are included for locating and finding RF signals.
Tuning Station Example (Audible Feedback)
In this example an amplifier tuning station provides audible feedback to aid the technician in tuning the amplifier within its specified performance limits. The technician can tune the amplifier under a microscope, using the audio tones to indicate how close the device meets its specified performance window. The technician does not have to look up from his work to check an instrument panel to determine the results of his/her tuning.
R. A. Wood Associates can custom develop automated test software for your particular needs in your test station. We can provide and implement ideas to enhance your productivity.
Statistical Data Reduction and Analysis
R. A. Wood Associates Software can save valuable test and debug time by analyzing and summarizing large quantities of data. This example shows the result of taking 500 frequency readings from a Digital Frequency Discriminator (DFD) under low signal to noise ratio conditions. The DFD frequency error is plotted on the graph vs input frequency. The statistics of the frequency error are evaluated in the Test Summary and compared against the specifications. The test operator obtains immediate feedback from the results of the measurements.
User Friendly Test System Interface
The LabVIEW software developed by R. A. Wood Associates provides a user friendly interface to the automated test setup. The computer screen is the Test Panel, where input test parameters are entered or selected. Selection switches can be placed on the screen to control the hardware being tested.
After the test is completed, the output data is summarized, plotted, and printed out. Actual test data points can be stored in data files if needed.
Typical Automated Test Setup (Microwave Test)
This diagram shows a typical computer automated test setup. In this application, a microwave device is tested using microwave test equipment such as the signal generator, spectrum analyzer, and power meter. The digital I/O controller provides the logic controls for the Device Under Test while the logic analyzer reads digital information from the device.
The computer acts as the automated test controller. It controls the microwave test equipment to provide stimulus and measurements to and from the Device Under Test. Digital control is passed from the computer through the digital I/O board. Digital output data is passed from the logic analyzer to the computer.
The R. A. Wood Associates software will control the testing and analyze the measurements. Typical measurements may include gain, noise figure, gain compression, spurious signals, filter rejection and amplitude accuracy. The measured data is then summarized, eliminating the need for manual data reduction. Output data can be stored in data files for further analysis and evaluation.
LabVIEW Example - Instantaneous Frequency Measurement (IFM)
2. Explanation of Parameters on Data Plots
An explanation of the parameters on the data plots shown in Appendix A is provided below.
2.1. Start, Stop and Step Frequencies
Frequencies used for test data.
2.2. Noise Power (dBm)
The wideband noise power across the 2 to 6 GHz frequency band. The noise source was provided by cascading several 2-6 GHz amplifiers together and tuning the amps for flat gain across the frequency band. The noise power was measured using a broadband power meter.
In the NB filter measurements, the noise power represents the noise power across the NB filter bandwidth measured using a broadband power meter.
The Signal to Noise Ratio at the IFM input. The SNR was achieved by combining the signal and noise and adjusting the input RF signal relative to the wideband noise power measured.
2.4. Pulsewidth (nSec)
The pulsewidth of the IFM enable (Freq Strobe). The pulsewidth determines how many samples are received from the IFM at each frequency. There will be 1 frequency reading or average frequency output every 100 nSec over the IFM enable time
2.5. Data < 4 MHz
The percentage of frequency readings that were less than 4 MHz error were calculated. The readings were flagged correctly if the Gross Freq Error Flag was 0, and the PMOP Freq Error Flag was 0, and the Quality Bits were greater than or equal to the Quality Bit Threshold. The readings were flagged incorrectly if the Gross Freq Error Flag was 1, or the PMOP Freq Error Flag was 1, or the Quality Bits were less than the Quality Bit Threshold. Percentages of data flagged correctly and incorrectly were summarized.
2.6. Data 4 - 20 MHz
The percentage of frequency readings that were between 4 and 20 MHz error were calculated. The readings were flagged correctly if the Gross Freq Error Flag was 0, and the PMOP Freq Error Flag was 0, and the Quality Bits were less than the Quality Bit Threshold. The readings were flagged incorrectly if the Gross Freq Error Flag was 1, or the PMOP Freq Error Flag was 1, or the Quality Bits were greater than or equal to the Quality Bit Threshold. Percentages of data flagged correctly and incorrectly were summarized.
2.7. Data > 20 MHz
The percentage of frequency readings that were> 20 MHz error were calculated. The readings were flagged correctly if the Gross Freq Error Flag was 1, or the PMOP Freq Error Flag was 1. The readings were flagged incorrectly if the Gross Freq Error Flag was 0, and the PMOP Freq Error Flag was 0. Percentages of data flagged correctly and incorrectly were summarized.
2.8. Quality Bit Threshold
The three quality bits comparing the last two correlator channels is an output of the IFM with each frequency reading. A seven (111) represents high correlation, and 0 (000) represents poor correlation between the correlator channels. The quality bits were compared against the Quality Bit Threshold to flag frequency readings in the range 4 to 20 MHz error. If the quality bits were less than the Quality Bit Threshold, and the Gross Freq Error and PMOP Freq Error were at logic 0, then the data would be flagged as a fine frequency error (4 - 20 MHz).
2.9. Gross Freq Error Threshold
The Gross Freq Error Threshold was programmed as an input to the IFM. If the worst case of all the correlator compares in the IFM is less than the Gross Freq Error Threshold, then the Gross Freq Error Flag is set to logic 1. The Gross Freq Error Flag is used to flagged errors > 20 MHz. See Appendix B for further information.
2.10. Gross PMOP Count Threshold
The Gross PMOP Count Threshold represents the number of IFM samples where the PMOP flag was looked at to determine low SNR conditions. If the the PMOP Flag was logic 1 at or before the Gross PMOP Count Threshold (no. of samples), then the PMOP Freq Error Flag would be set to logic 1. The PMOP Freq Error Flag is used to flag errors > 20 MHz. See Appendix B for further information.
2.11. PMOP Threshold
The type of phase modulation being detected (90° / 180°).
2.12. Sample No.
The plot shows results for the Sample No. on the left side of the plot. Note: the software program starts all arrays with element "0". Therefore, Sample 0 corresponds to the first frequency reading, Sample 1 corresponds to the second frequency average, etc.
2.13. Data Plots
The data plots on each page show test results for the Sample No. shown. The top trace shows the Quality Bits for each frequency reading. a 7 (111) represents good quality and 0 (000) represents poor quality.
The second trace shows the frequency error across the frequency band (MHz)
The third trace shows the Gross Freq Error Flag for each frequency reading. The trace is offset at -5 for clarity. When the value is -5, the flag is logic 0. When the value is -4, the flag is logic 1.
The fourth trace is the PMOP Freq Error Flag. If the PMOP flag is logic 1 in less than the Gross PMOP Count Threshold sample no, the PMOP Freq Error Flag is set to Logic 1. This trace is offset at -10 for clarity.
The fifth trace is the FMOP Flag, offset at -15 for clarity.
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