JTFA Spectrum Frequency

[toiletwto]

Hello all,

I've generated a BFSK sinwave (37kHz and 40kHz ) via DAQ card,

and I used JTFA vi to detect the signal I've received.

Sampling rate is 1MHz, N=1000 samples.

However, the y-axis(frequency) scale corresponded to the sampling rate,

if fs=1MHz, max of y-axis is 500kHz,

if fs=100kHz, max of  y-axis is 50kHz.

Since my signal is either 37kHz or 40kHz, 

500kHz is too large to distinguish them.
but if I decrease the sampling rate, the signal tend to be aliasing.

Is there any way that I can decrease the scale of y-axis but use bigger sampling rate?

[johnsold]

Turn off autscaling on the Y-axis of the graph. Then manually set the lower limit to 30 kHz and the upper limit to 50 kHz.

Lynn

[toiletwto]

Hello,

I've tried, but the resolution was quite low...

[ejkaiser]

If you want higher frequency resolution you have to increase the record length.