[SI-LIST] Re: si-list Digest V8 #298
- From: "Tom Dagostino" <tom@xxxxxxxxxxxxx>
- To: "'Tom Zych'" <Tom_Zych@xxxxxxxxxxxxxxxxxxx>, <si-list@xxxxxxxxxxxxx>
- Date: Thu, 25 Sep 2008 08:55:10 -0700
It's the spectrum not the clock frequency that needs to be sampled.
Sampling a 220 MHz clock signal with a 500ms/sec digitizer would not get
what you really want. Let's assume the 220MHz signal is just a square wave
clock. It's fundamental frequency is 220 MHz. The next frequency in the
Fourier series of a square wave is 3X the fundamental or 660MHz. Etc. The
actual spectrum of the 220MHz clock is dependent on the risetime of the
driver. The sampling rate of the digitizer should be high enough to capture
a bandwidth of 0.35/Trise. At best a 500MS/sec digitizer can capture a
1.4nsec risetime. We don't see many ICs that are that slow anymore.
Tom Dagostino
Teraspeed(R) Labs
13610 SW Harness Lane
Beaverton, OR 97008
503-430-1065
503-430-1285 FAX
tom@xxxxxxxxxxxxx
www.teraspeed.com
Teraspeed Consulting Group LLC
121 North River Drive
Narragansett, RI 02882
401-284-1827
-----Original Message-----
From: si-list-bounce@xxxxxxxxxxxxx [mailto:si-list-bounce@xxxxxxxxxxxxx] On
Behalf Of Tom Zych
Sent: Thursday, September 25, 2008 8:04 AM
To: si-list@xxxxxxxxxxxxx
Subject: [SI-LIST] Re: si-list Digest V8 #298
Nirmale -
First, the 6000-series have a maximum acquisition memory of 8 MPts. To
capture 50 msec would require a sample rate of no more than 8M/50m or 160
MSa/s. Since the signal you're trying to capture is 220 MHz, Nyquist says
that 160 MSa/s is too slow by a factor of three - you would need to sample
at 500 MSa/s on the scope in order to properly capture the signal. In other
words, it is not possible to capture 50 ms of a 220 MHz signal in one
acquisition with an MSO6104.
Second, I would ask why you believe you need to capture 50 ms of continuous
data versus e.g. 10 separate acquisitions of 5 ms each (which would allow
you to sample at 1 GSa/s into that 8 MPts of memory)? We encounter
customers every day who believe they need to capture huge amounts of data
all at once, when in reality capturing it in smaller chunks and combining
the analysis results will give them everything they need.
Third, (and I apologize for a tad of commercialism here) there are products
like ASA's M1 Oscilloscope Tools software that can acquire data from your
scope and do all sorts of analyses on it (including connecting to Matlab),
as well as help you to automate if this is something that you'll need to be
doing a lot. Take a look at www.m1ot.com and let me know if you have any
questions.
Regards,
Tom Zych
______________________________
Tom Zych
Chief Engineer
ASA Corp
phone: +1-413-596-5354
FAX: +1-413-596-9686
> From: "Nirmale G" <nirmale@xxxxxxxxxxxxxxx>
> Subject: [SI-LIST] Data Acquisition through Oscilloscope.
> Date: Wed, 24 Sep 2008 20:26:21 +0530
>
> Hi All,
>
> I have few questions on Agilent Oscilloscope (MSO6104A).
>
> I need to capture 20 single ended I/O lines at 1.2V CMOS
> logic level, toggling at 220 MHz from a test board. I want
> to use the logic analyzer in MSO6104A (16 digital + 4 analog
> ) to capture the data lines continuously. For this, I am
> using the IntuiLink Data Capture tool in Microsoft excel to
> capture this data via a USB interface from MSO. But in
> MSO6104, at one time I can capture only 50,000 points of what
> is present on the screen of MSO.
>
> I request you to address my following queries:-
>
> 1. How I should use the MSO to capture more number of
> points when
> compared to 50000. Is there a way to continuous capture of
> data in excel sheet through which, I can capture the 220MHz
> signal for a time period of 50msec. I require this so that I
> have more data to analyze offline in Matlab. At present
> 50000 samples is very less for analysis.
------------------------------------------------------------------
To unsubscribe from si-list:
si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field
or to administer your membership from a web page, go to:
//www.freelists.org/webpage/si-list
For help:
si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field
List technical documents are available at:
http://www.si-list.net
List archives are viewable at:
//www.freelists.org/archives/si-list
or at our remote archives:
http://groups.yahoo.com/group/si-list/messages
Old (prior to June 6, 2001) list archives are viewable at:
http://www.qsl.net/wb6tpu
------------------------------------------------------------------
To unsubscribe from si-list:
si-list-request@xxxxxxxxxxxxx with 'unsubscribe' in the Subject field
or to administer your membership from a web page, go to:
//www.freelists.org/webpage/si-list
For help:
si-list-request@xxxxxxxxxxxxx with 'help' in the Subject field
List technical documents are available at:
http://www.si-list.net
List archives are viewable at:
//www.freelists.org/archives/si-list
or at our remote archives:
http://groups.yahoo.com/group/si-list/messages
Old (prior to June 6, 2001) list archives are viewable at:
http://www.qsl.net/wb6tpu
Other related posts:
