# LimeSDR-USB transmitting issue

**URL:** <https://discourse.myriadrf.org/t/limesdr-usb-transmitting-issue/6993>\
**Category:** LimeSDR\
**Created:** [3 March 2021 09:34 UTC](https://discourse.myriadrf.org/t/limesdr-usb-transmitting-issue/6993 "2021-03-03T09:34:20Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![johnd](https://avatars.discourse-cdn.com/v4/letter/j/58f4c7/32.png) [@johnd](https://discourse.myriadrf.org/u/johnd)\
**Post date:** [3 March 2021 09:34 UTC](https://discourse.myriadrf.org/t/limesdr-usb-transmitting-issue/6993/1 "2021-03-03T09:34:20Z")

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Hi,

I’m experiencing some issues trasmitting with my brand new LimeSDR-USB (v1.4s) and GNURadio.

My setup is:

1. GNURadio 3.8.2 with gr-limesdr (latest commit from gr-3.8, [47511dd](https://github.com/myriadrf/gr-limesdr/commit/47511dd58de1695b70e1028366411bada85eb60f)) and LimeSuite (latest commit from master, [a45e482](https://github.com/myriadrf/LimeSuite/commit/a45e482dad28508d8787e0fdc5168d45ac877ab5))
2. LimeSDR-USB v1.4s with latest gateware connected through USB3.0
3. Spectrum analyzer connected to TX1\_1 port from LimeSDR-USB

I configure GNURadio to produce a tone at 10kHz, amplitude 0.5, like this:

 ![Screenshot_20210303_101232](https://canada1.discourse-cdn.com/flex034/uploads/myriadrf/original/2X/9/9914a9cf141ce6b7979cc1b0d5755be40419584e.png)  
 ![Screenshot_20210303_101710](https://canada1.discourse-cdn.com/flex034/uploads/myriadrf/original/2X/7/7d0cdf4a55fd16df53266f1fa1c96b362f6ea411.png)

What I obtain in the spectrum analyzer is this:

 ![ScreenImg (8)](https://canada1.discourse-cdn.com/flex034/uploads/myriadrf/original/2X/d/db60489411f146db05270b5d33ca6b72da05ffcd.png)

I have a LimeSDR-Mini as well, so I’ve tried just swaping one Lime for the other, same configuration and flowgraph, and I get this:

 ![ScreenImg (9)](https://canada1.discourse-cdn.com/flex034/uploads/myriadrf/original/2X/b/b6fd36dd4b6dd325d0924b0ffa086bbda6417da2.png)

Then I’ve tried setting gain for LimeSDR-USB to 0, with the same result, just different scale.  
I have several LimeSDR-USB units, and all of them show the same results, so I think it’s a configuration issue.

I gave it another try using the ENABLE\_NEW\_GAIN\_BEHAVIOUR option in LimeSuite and recompiling everything, but was without luck.

Do you have any idea how to fix this?

Thanks in advance.

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<div class="post-metadata">

**Author:** ![johnd](https://avatars.discourse-cdn.com/v4/letter/j/58f4c7/32.png) [@johnd](https://discourse.myriadrf.org/u/johnd)\
**Post date:** [3 March 2021 11:27 UTC](https://discourse.myriadrf.org/t/limesdr-usb-transmitting-issue/6993/2 "2021-03-03T11:27:55Z")

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I’m experiencing the same issue with basicTX example from LimeSuite so I guess this is not up to GNURadio or gr-limesdr.