4DSP Support Forum

Products => FMC Products => FMC150 => Topic started by: rajeshsub on April 16, 2014, 04:56 AM

Title: changing the sampling freq.
Post by: rajeshsub on April 16, 2014, 04:56 AM

Since the VCXO values are fixed at 491.52 Mhz, and my design requires 160 Mhz for ADC and 320Mhz,
can i get these values using internal clock, please guide.
incase i use external clock option what are things i need to take care.
 
Thanks and Regards,
Rajesh S

Title: Re: changing the sampling freq.
Post by: ebarhorst on April 22, 2014, 11:19 AM

Hi,


correct, with internal clock your onboard VCO needs to be  an integer multiple of your target clock frequency.


With external clock the PLL is not used and the clock is distributed and divided only. These are settings that you need to set in the PLL device. Our standard reference software does already support the option to choose external clock. You can use this as a starting point.


NOTE: the input data delays for the ADC data depend on the ADC clock frequency. You may need to tune this delay value to have correct data sampling at frequencies that differ from the standard frequencies.


Best regards,
Erik

Title: Re: changing the sampling freq.
Post by: arnaudNL on June 13, 2014, 07:52 AM

This topic is being closed because the issue is considered as resolved by 4DSP. Feel free to create a new topic for any further inquiries.