# USRP1 XCV2450 LO - can it be bypassed with the motherboard's LO

**URL:** <https://www.ruby-forum.com/t/usrp1-xcv2450-lo-can-it-be-bypassed-with-the-motherboards-lo/220429>\
**Category:** GNU Radio\
**Created:** [June 8, 2012, 11:12pm UTC](https://www.ruby-forum.com/t/usrp1-xcv2450-lo-can-it-be-bypassed-with-the-motherboards-lo/220429 "2012-06-08T23:12:55Z")\
**Posts on this page:** 4\
**Page:** 1

<div class="post-metadata">

**Author:** ![aris](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/a/258eb7/32.png) [@aris](https://www.ruby-forum.com/u/aris)\
**Post date:** [June 8, 2012, 11:12pm UTC](https://www.ruby-forum.com/t/usrp1-xcv2450-lo-can-it-be-bypassed-with-the-motherboards-lo/220429/1 "2012-06-08T23:12:55Z")

</div>

Hello,

we have a USRP1 with 2 XCVR2450 daughtercards. Each XCVR2450 has its  
own LO however , we would like to bypass it with the motherboard’s  
X-TAL source.  
Both XCVR2450 daughtercards will then be driven synchronously by the  
motherboard.

Is this possible ? If so, is there a schematic of the XCVR2450 and  
motherboard which will show the required jumpers and/or SMTs ?

If not, which USRP (2 ? ) and daughtercards do we need ?

Thank you,  
Nick and Han  
UIC wireless lab

---

<div class="post-metadata">

**Author:** ![Nick\_Iliev](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/n/b5a626/32.png) [@Nick\_Iliev](https://www.ruby-forum.com/u/Nick_Iliev)\
**Post date:** [June 9, 2012, 1:35am UTC](https://www.ruby-forum.com/t/usrp1-xcv2450-lo-can-it-be-bypassed-with-the-motherboards-lo/220429/2 "2012-06-09T01:35:29Z")

</div>

Each XCVR2450 is already locked to the motherboard crystal. But “bypass  
it  
with the motherboard’s  
X-TAL source” does not make sense. The LO is generated by locking to  
the  
motherboard crystal source. No bypassing is necessary.

Matt

---

<div class="post-metadata">

**Author:** ![Nick\_Iliev](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/n/b5a626/32.png) [@Nick\_Iliev](https://www.ruby-forum.com/u/Nick_Iliev)\
**Post date:** [June 9, 2012, 12:56am UTC](https://www.ruby-forum.com/t/usrp1-xcv2450-lo-can-it-be-bypassed-with-the-motherboards-lo/220429/3 "2012-06-09T00:56:55Z")

</div>

Google is your friend:  
[http://code.ettus.com/redmine/ettus/projects/public/documents](http://code.ettus.com/redmine/ettus/projects/public/documents)

---

<div class="post-metadata">

**Author:** ![Nick\_Iliev](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/n/b5a626/32.png) [@Nick\_Iliev](https://www.ruby-forum.com/u/Nick_Iliev)\
**Post date:** [June 16, 2012, 6:49pm UTC](https://www.ruby-forum.com/t/usrp1-xcv2450-lo-can-it-be-bypassed-with-the-motherboards-lo/220429/4 "2012-06-16T18:49:42Z")

</div>

Thanks for the clarification. We have both XCVR2450 TX boards (in  
the same TX USRP1 ) locked to 2.4GHz ( verified with a specturm  
analyzer ) . Now, the receiver XCVR2450 RX board (in the RX USRP1 )  
should be able to lock to 2.4GHz as well , right ?

We’re using default BPSK mod/demod for this 2 TX x 1 RX experiment.  
Both TX boards send BPSK symbols in the same time slot, and are  
tuned for 2.4GHz Is there a lock-detect pin on the RX side we can  
probe to verify that the RX board has locked to 2.4GHz ?

-Nick