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vector modulation traceability
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on Aug 13, 2007
on Aug 12, 2010 by hudla
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PSA and MXA series has vector demodulation mode. Uncertanty of demodulation is printed approx 1% (typical). What is guaranted spec? And wich kind of perfomace test is approved this?
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Aug 23, 2007 8:03 AM
Please call the Agilent Technical Contact center at 800 829-4444, use 89601 for an instrument model when prompted and ask for Brent when you reach somebody in the Wireless Devices group.
This too big of a topic to discuss in forum messages.
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Mar 17, 2008 3:41 AM
I have a similar question concerning a traceable calibration of a spectrum analyzer digital modulation functions. For modern Agilent instruments, there exist the Agilent N7800A Test Management Environment with tests specified for various instruments. The calibration of basic RF and IF functions is possible to make traceably. However, I can see a problem with the calibration of functions related to modern modulations (EVM, Rho, phase, frequency error, ACPR, phase noise, ...). Let's take for example PSA spectrum analyzer: to test the IF amplitude and phase ripple (to meet EVM specifications), I need a calibrated vector signal generator (PSG or 443x are recommended). To calibrate the signal generator's digital modulation functions, I need a calibrated spectrum analyzer or signal analyzer (which is a closed loop, in my opinion).
From the previous, it seems for me that when calibrating the spectrum (or signal) analyzer's digital modulation functions, I need a vector generator and to "trust" its specifications. When calibrating a vector generator, I need a spectrum (or signal) analyzer and I have to "trust" its specifications again, in other cases the calibration process makes a closed loop. In my opinion, it is not possible to test e.g. the EVM specification of a spectrum analyzer just by bringing a test signal (with poorly known precission) to its input. The process of down-converting, demodulation, A/D conversion etc. introduces many sources of error, which are not evaluated in this manner. Is this the way how Agilent internally tests its own instruments, or do they use some "higher level" accuracy procedures?
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Mar 17, 2008 7:04 AM
this is too big a topic to handle in e-mail. If you could call the Agilent Technical Contact center, use 89601 for the instrument as you follow the prompts to tech support and ask your questions of our tech support team you will get a faster response for this one than through the forum.
I would call you myself today, but we just switched over to a new call traffic handling software package that has us all scrambling for a week or so.
My name is Brent Reed, and if you wish, you may ask for me when you call in, but I do suggest you wait till later in the week if you can until the call volume settles down.
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Aug 12, 2010 3:43 AM
the traceability for digitally modulated signals (both generating the signals and measurement ot their parameters) is problematic nowadays. This could change - the European union has recently launched a call for metrological research projects that should help the European industry's competitiveness and innovation. The projects are planned for 3 years starting in mid 2011. One of the potential projects is 'Metrology for Ultrafast Electronics and High-Speed Communications'. Further details about the project are published at
Now the SRT-09i project consortium consists of 9 national metrology institutes from 9 EU countries and several partnering institutions with lots of experience and facilities, which makes a critical mass to face challenging metrology tasks.
As the projects should mainly emerge from industry needs and going beyond the current state of the art, we're addressing main industry companies to express their interest in results of such projects. Several research topics are now being prepared within the SRT-09i project:
1) To develop time-domain waveform metrology allowing for complete characterisation of ultrafast devices and wideband sources used for traceable measurements.
2) To compare and validate frequency and time domain measurement techniques for the characterisation of future high-speed communication systems
3) To perform propagation measurements and channel and antenna characterisation in millimetric and sub-millimetric bands
4) To provide quantitative and reliable evaluation of high-speed communication system performance by traceable measurement of digital modulation properties (digital modulations traceability)
If you think there exist some measurement method in high-speed communications, which should be developed / improved / standardized (mainly concerning digital modulations), and which is beyond the current state of the art, please feel free to post it here or contact me. Any response or opinion from the industry is warmly welcome.
Czech metrology institute
Dept. of microwave measurement
Prague, Czech Republic
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