[USRP-users] E100 external reference and PPS

Nowlan, Sean Sean.Nowlan at gtri.gatech.edu
Tue Jun 19 14:26:14 EDT 2012


It has been 3 weeks and nobody has responded to this question. Is there anything special I need to do to enable the external reference and PPS inputs on the E100 (rev. 3)? My only thoughts are that 1) there's something magic I have to do to get the E100 in the mood to use the external reference, or 2) the GPSDO unit I'm using is broken and the E100 can't lock to it.

Since the E100 (rev. 3) isn't configured to automatically detect the Jackson Labs GPSDO and read its RS-232 output, I used Pin 3 to confirm that the GPSDO is locked.

Any thoughts? Also, if Ettus has the rev. 3 schematic available somewhere, that would be very helpful. Thank you!

Best regards,
Sean Nowlan

From: usrp-users-bounces at lists.ettus.com [mailto:usrp-users-bounces at lists.ettus.com] On Behalf Of Nowlan, Sean
Sent: Friday, May 25, 2012 6:12 PM
To: USRP-users at lists.ettus.com
Subject: [USRP-users] E100 external reference and PPS

Hi all,

I have an E100 (rev 3) and I would like to use an external reference and PPS. I soldered straight SMA connectors onto J10 and J13 (REF IN and PPS IN, respectively). I'm supplying a 10MHz and PPS reference to the board, but I'm not sure how to tell the clock gen circuit to use the external reference.

I tried set_clock_source("external", 0) but the reference won't lock. Do I need to burn an EEPROM setting as with the N2xx? Is there a jumper I need to change?

FYI I installed UHD 3.4.2 release.

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