I am trying to plot the Cross Ambiguity Function of two OFDM signal (1024 subcarriers) reflected from two targets, which are separated by 30m. The problem I am facing that the CAF peak width at the range domain is wide (zero-doppler cut), which means that the range resolution is too low. So, I am just wondering how would it be possible to reduce the peak width to get high range resolution? (Note that CAF peak width at doppler domain is sharp (zero-delay cut).


1 Answer 1


Assuming this is a RF system. What is the bandwidth of the waveform? The range resolution $\Delta R$ achieved by a matched-filtered waveform is given by

$$\Delta R = \frac{c}{2\beta}$$

Where $c$ is the speed of light and $\beta$ is the bandwidth of the waveform. A range resolution of 30 m requires a bandwidth of 5 MHz. Is your bandwidth lower than this? If it is, that's your problem: you must increase the bandwidth of the waveform you're transmitting.

  • $\begingroup$ The BW of the baseband ofdm signal is around 1 kHz. $\endgroup$ Commented May 13, 2022 at 16:48
  • $\begingroup$ @wesamamiri Have you tried increasing the bandwidth by adding more channels or widening the current ones? If you do that and then match filter, you should see your lobe sharpen up. $\endgroup$
    – Envidia
    Commented May 13, 2022 at 20:27
  • $\begingroup$ I am trying to increase the BW, but I am facing some difficulties since I use the matlab OFDM function. Is there any way to widen the subcarriers? $\endgroup$ Commented May 13, 2022 at 22:51
  • $\begingroup$ @wesamamiri Would you mind showing your MATLAB code? $\endgroup$
    – Envidia
    Commented May 14, 2022 at 19:57
  • $\begingroup$ Sure, I can send it to you personally by email if that works for you $\endgroup$ Commented May 14, 2022 at 22:37

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