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3205 bandwidth Vs USB transport speed

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3205 bandwidth Vs USB transport speed

Postby notxor » Thu May 24, 2007 8:48 am

I have a question about the data transport process.
The 3205's bandwidth is 100MHz, since its resolution is 8bits, so 3205 have 100MB data per second to send to PC. But the USB2.0 have 480Mbps bandwidth=60MB/s, how can the USB transport 3205's data?
This question confused me for a long time. Thank you!
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Postby markB » Thu May 24, 2007 1:09 pm

The PS3205 will work in one of two modes, block or streaming.

In streaming mode, data is streamed into the PC continuously. This can be done at a maximum sample rate of 1kSps (samples per second).

In block mode, data is collected at 100MSps and stored into RAM on the PS3205 itself. After collection is complete, data can be sent back to the PC across the USB bus at the slower rate.


The maximum sample rate, 100MSps, is only achievable in block mode.
Regards

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Postby notxor » Fri May 25, 2007 3:07 am

Thank you for your reply! And more question:-) Can I select the working mode in the software picoscope?
In my opinion, if I wanna see the realtime waveform in picoscope, 3205 will work in streaming mode automaticlly. When I use Picolog, 3205 will switch to block mode itself. Is that right?
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Postby markB » Fri May 25, 2007 10:43 am

PicoScope will automatically switch to streaming mode when you select a timebase of 200ms/div or slower. For 100ms/div and faster, block mode is used.


PicoLog has have three modes: Real time continuous, streaming and fast block. Fast block uses the PS3205's block and streaming uses streaming. Real time continuous uses block mode to collect as many samples as it can for every sample PicoLog takes eg if you ask picolog for a sample every second, the PS3205 will ask for many samples over that second and report an average for the result.
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Postby notxor » Mon May 28, 2007 2:39 am

Thank you very much!
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