technical queries

[Sahara]

i m urgently looking for answers of this questions. please help me to solve it as soon as possible.

1. what is form factor?..i heard named 3U/6U. what is it?.now a days 6U format or 3U formate with 64 bit available..what is 64 bit?..

2. what is the data transfer rate for PXI?.PXI has version 2.1..what is it?

3.why record length has two much important now a days?.what role record lenth play at the time of acquisition

4. what is waveform capture rate and waveform update rate?

5. what is the main reason that sampling rate require higher than that of original frequency?.

[mister_rf]

Need to read this first
http://www.tiepie.com/uk/classroom/Measurement_basics/Digital_Data_Acquisition.html

1. what is form factor?..i heard named 3U/6U. what is it?.now a days 6U format or 3U formate with 64 bit available..

http://industrial-computers.globalspec.com/Specifications/Industrial_Computers_Embedded_Computer_Com...
http://en.wikipedia.org/wiki/VPX
http://www.interfacebus.com/Design_VME_Card_size.html

what is 64 bit?..

A 64-bit PCI bus provides higher overall throughput for high-performance adapters and better system efficiency by providing the same data in fewer PCI clock cycles.
http://www.compute-aid.com/64bitpci.html 
http://www.orbitmicro.com/support/resources/riser_cards/64bit_pci_definition.html

2. what is the data transfer rate for PXI?.PXI has version 2.1..what is it?

http://www.interfacebus.com/Design_Connector_PXI_Bus.html
http://labview.ilc.edu.ru/LVcenter/Files/pcigpib.pdf
http://www.tmworld.com/contents/pdf/20105ptr.pdf

3.why record length has two much important now a days?
A real time multi-channel digital storage oscilloscope acquires a relatively long data record for each channel in an acquisition memory and processes the data of the relatively long data record to search for predetermined events. Upon detection of such a predetermined event, circuitry generates an event detect signal, and data comprising an acquisition frame surrounding the event is applied to a waveform processing and display system. The relatively long data record can be replayed in order to perform additional searches throughout the data record using different search criteria, thereby permitting multiple waveforms to be displayed simultaneously, each being captured as a result of a different user-defined event.

4. what is waveform capture rate and waveform update rate?

http://www.edn.com/article/CA198888.html

5. what is the main reason that sampling rate require higher than that of original frequency

Some theory here
http://en.wikipedia.org/wiki/Sample_rate_conversion

 the sampling theorem.
 Frequently this is called the Shannon sampling theorem, or the Nyquist sampling theorem, after the authors of 1940s papers on the topic. The sampling theorem indicates that a continuous signal can be properly sampled, only if it does not contain frequency components above one-half of the sampling rate. For instance, a sampling rate of 2,000 samples/second requires the analog signal to be composed of frequencies below 1000 cycles/second. If frequencies above this limit are present in the signal, they will be aliased to frequencies between 0 and 1000 cycles/second, combining with whatever information that was legitimately there.

 

Message Edited by mister_rf on 04-27-2008 05:05 AM

[Sahara]

hi to all

i m looking for one digitizer of 150 MHz on PXI platform. which has 12 bit of resolution with 300 MS/s of sampling rate. does any company has this kind of card.if yes, than please let me konw.

also i am looking for one SIne and Square wave generator of 150 MHz with 10 bit of resolution. does any body has in the world.

please help me to get both cards details as soon as possible.

Sahara Agrasen