RPiks / pico-hf-oscillator

Digital controlled radio frequency oscillator based on Raspberry Pi Pico (1 Hz to ~32.333 MHz band). RTTY, MFSK, freq sweep examples are included.
MIT License
28 stars 7 forks source link

[Question] How "PLL principle" compares with DDS? #2

Open KestutisMa opened 7 months ago

KestutisMa commented 7 months ago

Dear Roman, I have analyzed your code with interest. It looks like your method share similarities to Time-Average-Frequency Direct Period Synthesis (TAF-DPS). I read about TAF method in wikipedia and some recent research papers (mostly by same authors). Also, it is mentioned in papers, that TAF may be not very good for RF applications, because of spurs.

Are there many spurs? and how do they change when changing frequency? And why didn't you choose DDS method?

I am thinking if it would be feasable to build IQ signal generator for HF receiver with comparable noise/distortion characteristics to popular Si5351 clock module?

Best, Kestutis

bradshawlupton commented 7 months ago

Kestustis, please consider a low pass filter or band pass filter first. then I always like trying something, not trusting the experts.  Bradshaw K1TE/WB2TEV Buzzards Bay MA.  Trial and error and error, is an amazing teacher.

Sent with Proton Mail secure email.

On Tuesday, January 30th, 2024 at 9:58 AM, Kestutis Maciunas @.***> wrote:

Dear Roman, I have analyzed your code with interest. It looks like your method share similarities to Time-Average-Frequency Direct Period Synthesis (TAF-DPS). I read about TAF method in wikipedia and some recent research papers (mostly by same authors). Also, it is mentioned in papers, that TAF may be not very good for RF applications, because of spurs.

Are there many spurs? and how do they change when changing frequency? And why didn't you choose DDS method?

I am thinking if it would be feasable to build IQ signal generator for HF receiver with comparable noise/distortion characteristics to popular Si5351 clock module?

Best, Kestutis

— Reply to this email directly, view it on GitHub, or unsubscribe. You are receiving this because you are subscribed to this thread.