Grace:
I frequently have to measure the amplitude and duration of very low duty cycle
pulses for military testing (although the FCC may have some variations on the
technique I use).
Typically, I use a spectrum analyzer to acquire the signal in a traditional
manner. For example, suppose I'm looking at a 2.4 GHz emission that transmits
a 6 millisecond duration digital word every second. I find the signal, center
it and then narrow the span to show the emission, possibly using a span of 20
MHz and an RBW of 100 kHz (VBW always > RBW).
I then set the span to zero Hz, set the sweep speed to about 5 mS per
division, and select Video triggering. (Newer, better analyzers than my
HP-8566B may allow faster sweep speeds which will allow better resolution of
the duration.) This will allow you to record a trace that will remain until a
new pulse paints a new waveform. You should then verify that you are reading
the true peak level by increasing the RBW. When an increase in RBW doesn't
yield a stronger signal level, you know that you are then reading the correct
amplitude.
You might also want to use Peak Hold if you want to catch the highest
amplitude, longest duration pulse over a long time period.
Ed Price
[email protected] <blocked::mailto:[email protected]> WB6WSN
NARTE Certified EMC Engineer
Electromagnetic Compatibility Lab
Cubic Defense Applications
San Diego, CA USA
858-505-2780
Military & Avionics EMC Is Our Specialty
________________________________
From: [email protected] [mailto:[email protected]] On Behalf Of Grace
Lin
Sent: Monday, June 01, 2009 12:13 PM
To: [email protected]
Subject: Power Measurement per FCC DTS Measurement
Dear Members,
Could someone please instruct me how to measure transmission pulse
duration
(T) per the FCC DTS Measurement (https:
/fjallfoss.fcc.gov/oetcf/kdb/forms/FTSSearchResultPage.cfm?id=21124&switch=P)?
Can I use a spectrum analyzer? If yes, what are the settings for RBW, VBW,
etc.? I have to measure the transmission pulse duration in order to apply an
appropriate method to measure power output for an IEEE 802.11 a/b/g device.
Thank you and look forward to hearing from you.
Best regards,
Grace Lin
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