# Two RX paths

**URL:** <https://www.ruby-forum.com/t/two-rx-paths/237847>\
**Category:** GNU Radio\
**Created:** [December 3, 2013, 5:12pm UTC](https://www.ruby-forum.com/t/two-rx-paths/237847 "2013-12-03T17:12:05Z")\
**Posts on this page:** 3\
**Page:** 1

<div class="post-metadata">

**Author:** ![musicdenotation](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/m/ea666f/32.png) [@musicdenotation](https://www.ruby-forum.com/u/musicdenotation)\
**Post date:** [December 3, 2013, 5:12pm UTC](https://www.ruby-forum.com/t/two-rx-paths/237847/1 "2013-12-03T17:12:05Z")

</div>

Hi all guys,

I would like to receive in my application signals from WBX board and  
from  
LFTX simultaneousely.  
At the moment, when I run the flow graph it ends immediately with core  
dump, and zero divisin exception.

In the script, sources are defined in this way:

```
    self.uhd_usrp_source_0 = uhd.usrp_source(
        device_addr="",
        stream_args=uhd.stream_args(
            cpu_format="fc32",
            channels=range(1),
        ),
    )

    self.uhd_usrp_source_0.set_subdev_spec("A:0", 0)
    self.uhd_usrp_source_0.set_samp_rate(samp_rate_wbx)
    self.uhd_usrp_source_0.set_center_freq(433900000, 0)
    self.uhd_usrp_source_0.set_gain(input_gain_slider_wbx, 0)
    self.uhd_usrp_source_0.set_antenna("RX2", 0)

```

and the second:

```
    self.uhd_usrp_source_1 = uhd.usrp_source(
        device_addr="",
        stream_args=uhd.stream_args(
            cpu_format="fc32",
            channels=range(1),
        ),
    )

    self.uhd_usrp_source_1.set_subdev_spec("B:A", 0)
    self.uhd_usrp_source_1.set_samp_rate(samp_rate_CC1000)
    self.uhd_usrp_source_1.set_center_freq(freq_CC1000, 0)
    self.uhd_usrp_source_1.set_gain(gain_CC1000, 0)

```

There are certain posts about using different firmware, but I am not  
able  
to figure out what should I really do, and is that necessary?

Thanx for help,

Best,

---

<div class="post-metadata">

**Author:** ![Nemanja\_S](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/n/7bcc69/32.png) [@Nemanja\_S](https://www.ruby-forum.com/u/Nemanja_S)\
**Post date:** [December 3, 2013, 5:16pm UTC](https://www.ruby-forum.com/t/two-rx-paths/237847/2 "2013-12-03T17:16:45Z")

</div>

On 12/03/2013 11:10 AM, Nemanja S. wrote:

> ```
> device_addr="",
> self.uhd_usrp_source_0.set_antenna("RX2", 0)
> 
> ```
> 
> Best,
> 
> –  
> Nemanja Savić
> 
> * * *
> 
> Discuss-gnuradio mailing list  
> [removed\_email\_address@domain.invalid](mailto:removed_email_address@domain.invalid)  
> [Discuss-gnuradio Info Page](https://lists.gnu.org/mailman/listinfo/discuss-gnuradio)  
> You need to specify the dual-DDC image for USRP1:

usrp1\_fpga\_4rx.rbf

[http://files.ettus.com/uhd\_docs/manual/html/usrp1.html#specify-a-non-standard-image](http://files.ettus.com/uhd_docs/manual/html/usrp1.html#specify-a-non-standard-image)

---

<div class="post-metadata">

**Author:** ![Nemanja\_S](https://www.ruby-forum.com/letter_avatar_proxy/v4/letter/n/7bcc69/32.png) [@Nemanja\_S](https://www.ruby-forum.com/u/Nemanja_S)\
**Post date:** [December 3, 2013, 5:25pm UTC](https://www.ruby-forum.com/t/two-rx-paths/237847/3 "2013-12-03T17:25:31Z")

</div>

I see, but still don’t get where this change should be made.  
And also, more important, i I have standard configuration with 2 DDCs  
and 2  
DUCs, then it should work like that, cause I need only 2 DDCs if I am  
not  
wrong.