User guide

Altera Corporation 13
Exercise 1: Review the Filtering Lab Design
Table 3 lists the parameters for the NCO_10MHz block that you
can set in the Parameters tab.
The NCO_10MHz block contains the same parameter values as the
NCO_1MHz block, except for the constant value that is input to the
Phase Increment Value. The constant value determines the frequency
of the NCO sinusoidal output. The NCO Compiler MegaCore
function calculates the constant value when you enter the Clock Rate
and the Desired Output Frequency in the wizard. Figure 6 on page 8,
shows the calculated result for a 1-MHz sine wave at 42,949,673. The
Clock Rate corresponds to the 100-MHz on-board oscillator on the
Stratix II EP2S180 DSP development board. Similarly, the Desired
Output Frequency of 10 MHz yields a Phase Increment Value of
429,496,730 (see Figure 8).
Table 3. NCO_10MHz Compiler - Parameters Tab
Parameter Value
Under Generation Algorithm
Multiplier-Based Select
Under Precisions
Accumulator Precision (in bits) 32
Angular Precision (in bits) 12
Magnitude Precision (in bits) 13
Under Phase Dithering
Implement Phase Dithering Turn on
Dither Level 4
Under Generated Output Frequency Parameters
Clock Rate 100 MHz
Desired Output Frequency 10 MHz