--- In [email protected], "D. J. Wang" <[EMAIL PROTECTED]> wrote: > > Hi Janne, > An PLL LO with large step size indeed made tunning more difficult if you have to manually adjust both PLL freq and Winrad receive > freq. It may not be a problem if you have both under "software" control.
This could be achieved by using a user DLL interfaced with Winrad, written according to the specs I published on my Web site. >From the inside of that DLL you can both change the hardware LO, by controlling the DDS, and being informed by Winrad about the new software NCO frequency tuned to by the user, so that when it approaches the passband limits, a new DDS frequency can be set. > For your application (Frcv >50 MHz) single DDS may not be a good idea since a LO >200MHz is needed to generate I/Q signals you > need, this will definitely give you higher spur. Giuliano I0CG has just receive a couple of samples from Analog Devices of their new DDS with clock up to 1 GHz. Using this chip, it will be possible to cover the 50 MHz band with very few spurs, surely much less than with ad9951/54 chip. 73 Alberto I2PHD [Non-text portions of this message have been removed]
