Sample a 175kHz with a sampling rate of 10MHz

[ashifulk]

I'm trying to sample a 175kHz AC signal with a sampling rate of 10MHz using a NI USB-6343 but I am unable to get the code to work. I cannot use the "Sample Clock" because my required sampling rate exceeds its capability(?). I'm trying to use an external clock but I also get the the following error:

Error -200284 occurred at Voltage - Finite Input.vi

Some or all of the samples requested have not yet been acquired.

Right now I'm using the DAQmx example "Voltage - Finite Input.vi" and I was trying to use the "/Dev2/FrequencyOutput" for the Sample Clock Source. I also don't see any output on the graph. I'm assuming this is happening because I need to wire a trigger to the NI DAQ box. Is that correct? I'm not sure which pins to wire other than the analog input. Any help is greatly appreciated.

Thank You.

[crossrulz]

You really should go with a PCI card that can actually handle the 10MHz sample rate.  Trying to force a D/A to go 20X what is it rated for is just asking for trouble.

[ashifulk]

Unfortunately I can't get a PCI at the moment but I will look into it.

[ashifulk]

Is there a way I can use a external clock to sample at 1MHz? Or is the analog input fixed at 500kHz no matter what type of clock I use? I was hoping I could use the counters on the device as the clock and sample at 1MHz.

[johnsold]

No. You cannot make it go any faster with an external clock.  Even if the A/D converter could handle the faster clock, there are data buffers and communications to the host to be considered.  None of those circuits were designed to handle the faster rates.

Lynn

[ashifulk]

That's what I was thinking. Thank you.

[Henrik_Volkers]

A quick lookup in the spec, this card probably works with multiplexing, and sample 500kSPS on each channel. If you really want more samples you can try to feed more input channels with the signal and merge them yourself. The tricky part is to find out if you really got more bandwith with such a setup AND you should start thinking about source, cable and input impedances.. even if the RF guys would call 175kHz an unstable DC 😉

An easy test would be to hook up a sine generator with 200kHz to more than one channel and have a look at the data. apply a extract single tone on both signals and have a look at the phase 🙂