# Sweep Priority Complete a full sine wave or sweep time

Question asked by jcanyon on Apr 20, 2018
Latest reply on May 29, 2018 by KennyG

Hello.

I have the AD9914 EVK operating in swept frequency mode.  In this mode, you offer frequency step AND Sweep duration.  I am writing to determine the chip algorithm / priority.

Given the example Fstart =400MHz  Fstop=450MHz  Fstep=10MHz  Sawtooth mode Sweep time =24.6e-9 Sec.

This example (Used to make a point, not implimentable) sweeps 11 frequencies.  Will the dwell time be 24.6e-9  / 11 or will the dwell time vary so the DDS completes a complete sine wave then moves to the next - noting 1/400MHz takes more time than 1/450MHz.

This example is detailed below.  Note in order to complete one full cycle of each of the 11 steps below it takes 24.6e-9 seconds.

Thanks!  Jim

 Step Freq Duration of one cycle 1 4.00E+08 2.50E-09 2 4.10E+08 2.44E-09 3 4.20E+08 2.38E-09 4 4.30E+08 2.33E-09 5 4.40E+08 2.27E-09 6 4.50E+08 2.22E-09 7 4.60E+08 2.17E-09 8 4.70E+08 2.13E-09 9 4.80E+08 2.08E-09 10 4.90E+08 2.04E-09 11 5.00E+08 2.00E-09