kirgizz
Member level 2
Hi,
in order to continue my DSP work I'm facing a problem with phase.
In my DSP design based on ADSP21262EVM I generate a sine wave from a sine table. Required quality of the wave is ok, but there is something wrong.
I feed a sine wave with fixed frequency from an external source into DSP. At the same time my internal sine wave is generated with the same frequency. Both signals are led to the analogue output of the board. My digital real-time oscilloscope shows both signals running "against each other": they are not synchronous, the phase between them is NOT constant (need constant phase).
Yes, the reason could be my software algorithm. But what? I tested an another sine oscillator (quadrature coupled sin/cos oscillator) and the result is the same. Apart from the sine oscillator my program contains codec and peripherals configuration routines only, data RX/TX is interrupt driven.
The table-based sine algorithm were tested on Motorola DSP56L307EVM board too: the phase between arrival and generated sine was constant. A hardware problem?
Anyone can give me some advice for possible cause?
Thank you in advance
in order to continue my DSP work I'm facing a problem with phase.
In my DSP design based on ADSP21262EVM I generate a sine wave from a sine table. Required quality of the wave is ok, but there is something wrong.
I feed a sine wave with fixed frequency from an external source into DSP. At the same time my internal sine wave is generated with the same frequency. Both signals are led to the analogue output of the board. My digital real-time oscilloscope shows both signals running "against each other": they are not synchronous, the phase between them is NOT constant (need constant phase).
Yes, the reason could be my software algorithm. But what? I tested an another sine oscillator (quadrature coupled sin/cos oscillator) and the result is the same. Apart from the sine oscillator my program contains codec and peripherals configuration routines only, data RX/TX is interrupt driven.
The table-based sine algorithm were tested on Motorola DSP56L307EVM board too: the phase between arrival and generated sine was constant. A hardware problem?
Anyone can give me some advice for possible cause?
Thank you in advance