Re: [Discuss-gnuradio] Frequency resolution of CORDIC algorithm

[Matt Ettus]

Trond Danielsen wrote:
> 2007/6/28, Johnathan Corgan <address@hidden>:
> > Thus, for DC, the phase increment value is zero, for 0.0149 Hz, it
> is 1,
>> for 0.0298 Hz, it is 2, all the way up to 32 MHz, where it is pow(2,
>> 31).  You can also tune negative frequencies, where -1 creates -0.0149
>> Hz, etc.
>
> There is one more thing that I just can not figure out. The largest
> angular rotation that can be performed by the CORDIC is +/- pi/2,
> which means that is takes four cycles to rotate the vector all the way
> around. How come the largest frequency that can be generated be 32
> MHz.

If you look in the cordic.v file you will see that the actual CORDIC is
preceded by some logic which rotates by 0, 90, 180, or 270 degrees.

Matt