Monday, January 11, 2010

500kHz - subharmonic DC-RX or I/Q-SDR

My earlier mistake (4060) was resulting in the birth of a new idea.

Subharmonic stuff needs the local oscillator of half the operating frequency, so, a rather stable subharmonic local oscillator for 500kHz could be made by using a 4060 ripple counter w/ internal oscillator which divides by 16 at Q4 (pin 7). Sure, in this design, a crystal should be used. I figure this will make a nice and stable local oscillator for a subharmonic direct conversion receiver for the 501 to 504kHz band. Any drift of the crystal will have a 1/8 effect on 500kHz.

Depending on what is going on between 495 and 499kHz, image canceling could be considered.

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