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A particular communication system I came across defines chip time to be 0.57 ns and consequently chip rate is 1760 MHz.

The transmission bandwidth is 2.16 GHz.

I am wondering, do we suspect to have aliasing? Given the fact that the chip rate is smaller than the bandwidth of transmission? In other words shouldnt the sampling rate (which I assume is 1760 MHz) be at least greater than 2.16 GHz so as to prevent aliasing?

Thanks

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  • $\begingroup$ Are you sure the chip period isn't $0.57\ \mu \text{s}$? $\endgroup$ – Jason R Jun 30 '15 at 11:33
  • $\begingroup$ Thanks, yes I am sure its nano sec... But sorry I had time the bandwidth is not correct. I shall edit my question. @JasonR $\endgroup$ – Henry Jun 30 '15 at 12:10
  • $\begingroup$ A transmission bandwidth of 2.16 GHz sounds very unlikely unless you are operating at a carrier frequency of 50 GHz or more. Also, if the chip time really truly is 0.57 nanoseconds, then the number of chips per second is not 1760, though the bandwidth of 1760 MHz =1.76 GHz sounds right (or half-right since the baseband bandwidth is doubled when you move to the passband, unless you switch to QPSK or do some pulse-shaping etc). $\endgroup$ – Dilip Sarwate Jun 30 '15 at 13:20
  • $\begingroup$ Thanks Dilip, you are correct in fact this example is given at 60 GHz carrier. 1) Isn't 1760 MHz the chip or symbol rate? 2) With this symbol rate being less than transmission bandwidth do we suspect aliasing, the reason I ask is that I know that the sampling frequency should be twice as much as bandwidth for real valued signal and slightly greater for complex? @DilipSarwate $\endgroup$ – Henry Jun 30 '15 at 14:31

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