FPGA analog input frequency measurement

[sunu]

Hi,

I am pretty new to labview..I need to change the frequency of my look up table in accordance with an analog input signal frequency....This can be done by changing my scan rate which is calculated as follows

scan rate=FPGA frequency(40 Mhz)/16*fin

I decided 2 possibilities to implement this...

1)I could simply measure the frequency of the incoming analog signal from the photo detector...

Please tell me how to measure this frequency on FPGA??

2)I could also measure the phases of the signals and thus update the frequency.

But I dont exactly know how to do this....

It would be really helpful if you can help me resolve this ASAP

Thank You

[JoeySpinella]

Hi Sunu,

To measure the frequency of an analog signal on FPGA, I would recommend using the Analog Period Measurement Express VI.

Here is the help information for it:

http://zone.ni.com/reference/en-XX/help/371599J-01/lvfpga/fpga_period_measurement/

It will output the number of samples per period. The inverse of this will give you the frequency of the signal per samples. Multiplying by the sampling rate will then give you the frequency with respect to time.

You can then use this frequency in your calculations.

[IñigoP]

I had a problem with this block to measure the frequency of the FPGA. Now it is working. Thank you.

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@JoeySpinella 

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