Sampling rate of 400kHz

Hello everyone,

I have an ultrasonic signal of 40kHz which need to be send to an ADC(from a PIC) to the serial port of the PC and hence analysing it. To clearly analyse the signal, I believe I need a sampling rate of atleast 400kHz to have nice and clear signal. I have been browsing around microchip and I could not find any PIC sampling at this rate.

My questions are:
(1) Is there any other way to do it(interfacing external ADC to PIC)?

(2) Is there any other way to do it instead of using microcontroller to interface to the serial port?

Any help is greatly appreciated!!

Thanks a lot!!

anyone to help me please??

which need to be send to an ADC(from a PIC) to the serial port of the PC

this line is not clear............,

but to achieve high sampling rates you can explore "overclocking" the PIC to say 20 MHz or more. the PIC sends the ADC samples to a application ( VB ) thru serial port at say 115200 baudrate, the VB application then plots the ADC values according to time periods.





Arun

I meant : The analog signal is sent to the ADC in the microcontroller and that digital data send to the serial port of a laptop.

The PIC is already clocking at 20MHz.
Even if the sample rate is 400kHz, I dnt think serial port can handle that speed.
Am I right ?

So I was wondering if there is any other ways of doing this?

Thanks a lot!!

Take a look at this page
http://www.microchip.com/stellent/idcplg?IdcService=SS_GET_PAGE&nodeId=2551

Many high end Microchip devices can sample at 500k samples per second,
with a variety of high speed interfaces.
The obvious one for you being USB.

I dnt think serial port can handle that speed

in that case you can store samples in RAM for every second, say after collecting 2000 samples per second you send to serial port @ 115200 bps


one more thing since your signal is 40Khz, you can sample it at double the signal rate i,e 80khz. i don't remember, but there is a name for this kind of sampling .....yes, got it "Nyquist rate".

this is used in sampling speech, shreakiest female voice is around 4Khz and we get good output even when sampled @ 8Khz

you can also try capturing the 40Khz signal thru PC sound card (line in or Mic in - within 0- 5 Volts) but maximum sampling rate depends on the sound card ( normally it is limited to 48Khz)

Arun

Thanks a lot!

I dnt think there is any device which can give me 500ksps on microchip.

If I sample it at 80khz, would that give me a clear signal?

^^ provided the input signal doesn't cross the Nyquist frequency(which in this case is 40kHz) which would lead to aliasing...
You could use a 84kHz sampling rate which would give you 42kHz cutoff..2kHz margin to play with.