How to determine the sampling frequency? Edit
I have the following data from measurements:
Number of points =1000
frequency span =80 MHz
start frequency= 2.38 GHz
stop frequency= 2.46 GHz
sweep time/measurement duration= 90.09 ms
How can I determine the sampling frequency for FFT or IFFT to use in Matlab?
I heard the sampling frequency must be at least 2 times higher than the highest frequency?
Hi Geetanjali, can you explain VNA first? Anyway, the sampling frequency would be the number of points divided by the measurement duration, which is 1000/90.09/10^-3 = 11.1 KHz. However, it looks like the signal band is between 2.38 and 2.46 GHz (band width 80 M). If this is the case, then you have to increase the sampling frequency way up (according to the Nyquist rule ). You need to verify this.
Hello thanks for the answer, the VNA is a vector network analyzer, that is used to measure the channel impulse response of a wireless communication system.
If I make the signal bandwidth 10 Mhz will that work. Since the lower limit of points is 100 for 2.32 ms.
Yes, the sampling frequency need to be at least twice the highest frequency in the signal or you will get an aliased signal and loss important frequency components in the signal. So, you need to have pre-knowledge about the nominal signal frequency then setup the sampling frequency accordingly. I am attaching a link for a short article that might help.
http://www.ni.com/white-paper/3000/en/
Hi Geetanjali, sorry for late reply. It's not the bandwidth that matters but the LOWEST frequency of the SIGNAL TO BE MEASURED. when you say 'start frequency= 2.38 GHz', can you verify which does this correspond? The signal to be measured or the VNA frequency? If it's the former case, then I think you need to reconfigure the VNA and increase the sampling frequency DRAMATICALLY up.
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