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Using an external clock with the RSPIIpro

Posted: Wed Dec 06, 2017 4:34 pm
by Paul314
Using an Hp3325B function generator set to 24Mhz sine wave @ 1.5 volts peak to peak and the coupling circuit consisting of a 10nF capacitor with the radio side connected to ground through a 1.18k resistor[1] I get the following behavior. The external clock-in line is connected first. I then plug the radio into a USB hub which has an external power supply. The hub has an LED indicator light which normally would simply come on and stay on. With the external clock connected, the LED flickers and goes out. Is this the usual behavior? Both my radios do this. Also, with the USB LED indicator out, "mir_sdr_GetDevices" reports 0 devices. Could product support shed some light onto what's happening?

[1] This is the coupling circuit given in "RSP2 Reference Clock Application Note"

Re: Using an external clock with the RSPIIpro

Posted: Wed Dec 06, 2017 7:11 pm
by Tech_Support
Hello Paul314,
This is not a support forum. For support, please open up a support ticket at the url shown in the banner at the top of the page and we will try to help you.



Re: Using an external clock with the RSPIIpro

Posted: Thu Dec 07, 2017 7:38 pm
by Paul314
Okay, had a very helpful interaction with tech support and I should post a data dump here. The main source of my confusion was due to my external clock decided to put out 20MHz rather than the required 24MHz while I wasn't looking. The symptom using an external clock too far from 24MHz is the radio hangs-up and can't be reached by USB. I'm currently running both radios with the same external clock source and things appear to be working just fine. As far as I can see at the moment, both radios operating off of an external clock is the same as free running off their internal clocks as far as the software is concerned.