Hello Gary and all,

The point is do an experiment with your Stepping receiver.

Ken 

-----Original Message-----
From: Pettit, Ghery [mailto:ghery.pet...@intel.com]
Sent: Friday, December 07, 2001 8:36 AM
To: 'HALL,KEN (HP-Roseville,ex1)'; 'John Woodgate';
emc-p...@majordomo.ieee.org
Subject: RE: Stepping receiver, step sizes.


Ken,

A spectrum analyzer sweeps through a range of frequencies.  The resolution
of the display merely impacts the accuracy of the frequency determination
for a signal when digitized and sent to a computer over the bus.  Each point
on the display simply shows the highest level obtained in the range covered
by that point.  This is different than step tuning a receiver.

Or am I missing something?

Ghery Pettit
Intel

-----Original Message-----
From: HALL,KEN (HP-Roseville,ex1) [mailto:ken_h...@hp.com]
Sent: Friday, December 07, 2001 8:09 AM
To: 'John Woodgate'; emc-p...@majordomo.ieee.org
Subject: RE: Stepping receiver, step sizes.



Hello all,

We typically measure in 500 MHz spans, our spectrum analyzer has 400 bits so
1.25 MHz/bit. Concerned that we could miss an emission I perfromed the below
experiment, try it:

Injected a 2950 MHz signal into EMI Receiver, set for 1MHz RBW, and measured
it using diffrent Spans

3 000 MHz 67 dBuV signal, 400 bits 1 MHz RBW            
Span [MHz]      Amplitude       Step/bit [MHz]
10              66              0.025
500             67              1.25
1000            67              2.5
2000            67              5
3000            66              7.5
4000            67              10
6000            67              15

What we see is even with the step size 15 times the RBW the signal is not
lost.

Regards,

Ken Hall

 

-----Original Message-----
From: John Woodgate [mailto:j...@jmwa.demon.co.uk]
Sent: Thursday, December 06, 2001 2:16 PM
To: emc-p...@majordomo.ieee.org
Subject: Re: Stepping receiver, step sizes.



I read in !emc-pstc that Ken Javor <ken.ja...@emccompliance.com> wrote
(in <20011206195802.LCFL6698.femail7.sdc1.sfba.home.com@[65.11.150.27]>)
about 'Stepping receiver, step sizes.', on Thu, 6 Dec 2001:
>Keeping the step size to one-half the measurement bandwidth is an accepted
>way of assuring that all possible signals are captured.  Using a step size
>equal to a measurement bandwidth is not quite as good but reasonable.

In the context of 8, 20 or 80 kHz steps to cover 4 GHz, I think
reasonableness wins. One would be extraordinarily unlucky to lose a
significant signal under those conditions.
-- 
Regards, John Woodgate, OOO - Own Opinions Only. http://www.jmwa.demon.co.uk

After swimming across the Hellespont, I felt like a Hero. 

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