SDRplay Community Forum

Posted: **Wed Jul 05, 2017 12:27 pm**

In the application note for using the RSP2 reference clock, it says the clock source must be started before the RSP2 is plugged into the USB port. What behaviour occurs if the RSP2 is plugged in before the clock source is started? It appears that the RSP2 will still run if an external clock is turned on after plugging in the RSP2.

Thanks!

Posted: **Wed Jul 05, 2017 1:45 pm**

I don't know for sure, but I suspect the RSP2 looks for an ext clock on start-up, and if you apply the ext clock after it has started up it will not 'see' it and will use its internal clock. (Could be wrong, usually am!).

Posted: **Sun Jul 09, 2017 4:00 pm**

ERtpl wrote:In the application note for using the RSP2 reference clock, it says the clock source must be started before the RSP2 is plugged into the USB port. What behaviour occurs if the RSP2 is plugged in before the clock source is started? It appears that the RSP2 will still run if an external clock is turned on after plugging in the RSP2.

Thanks!

SDRPlay support team has answered it in another topic:

If you apply 0v DC to the reference input it switches from using the internal TCXO to the external clock. It is important that the clock is present and stable before the RSP2 is powered up as dynamically transitioning from one clock regime to another can cause glitches that leads to a lock up on an internal microprocessor within the RSP2 chipset.

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