# Minimum Bandwidth of the LimeSDR

**URL:** <https://discourse.myriadrf.org/t/minimum-bandwidth-of-the-limesdr/1452>\
**Category:** Applications\
**Created:** [12 July 2017 10:27 UTC](https://discourse.myriadrf.org/t/minimum-bandwidth-of-the-limesdr/1452 "2017-07-12T10:27:44Z")\
**Posts on this page:** 4\
**Page:** 1

<div class="post-metadata">

**Author:** ![Nolwenn](https://avatars.discourse-cdn.com/v4/letter/n/82dd89/32.png) [@Nolwenn](https://discourse.myriadrf.org/u/Nolwenn)\
**Post date:** [12 July 2017 10:27 UTC](https://discourse.myriadrf.org/t/minimum-bandwidth-of-the-limesdr/1452/1 "2017-07-12T10:27:44Z")

</div>

Hello,

I am using the LimeSDR as a scanner with GQRX. I need to detect radio waves around 2 GHz that are weak (around - 100 dBm or even less).  
That means that the noise floor has to be really low. I can get a noise floor around -110 dBm with the LimeSDR. It would be possible to decrease it even lower if I could reduce the bandwidth.  
However GQRX and GnuRadio crash if the bandwidth is lower than 1.4 MHz.

Could somebody give my a clue about that ?

---

<div class="post-metadata">

**Author:** ![hTo137](https://avatars.discourse-cdn.com/v4/letter/h/ba8739/32.png) [@hTo137](https://discourse.myriadrf.org/u/hTo137)\
**Post date:** [12 July 2017 17:05 UTC](https://discourse.myriadrf.org/t/minimum-bandwidth-of-the-limesdr/1452/2 "2017-07-12T17:05:56Z")

</div>

I recall something about this but no idea where I read that. Search here and look at gqrx and soapysdr on github issues. Someone here might actually know exactly why but IIRC it’s a bug. But I could misremember and it’s a feature/limitation.

---

<div class="post-metadata">

**Author:** ![Kc7noa](https://yyz2.discourse-cdn.com/flex034/user_avatar/discourse.myriadrf.org/kc7noa/32/144_2.png) [@Kc7noa](https://discourse.myriadrf.org/u/Kc7noa)\
**Post date:** [12 July 2017 18:24 UTC](https://discourse.myriadrf.org/t/minimum-bandwidth-of-the-limesdr/1452/3 "2017-07-12T18:24:06Z")

</div>

Not to be hurtfull … but i remember that the ADC has ~71db of dynamic range coupled with the LNA’s is lots of gain (for me)

---

<div class="post-metadata">

**Author:** ![Nolwenn](https://avatars.discourse-cdn.com/v4/letter/n/82dd89/32.png) [@Nolwenn](https://discourse.myriadrf.org/u/Nolwenn)\
**Post date:** [12 July 2017 18:59 UTC](https://discourse.myriadrf.org/t/minimum-bandwidth-of-the-limesdr/1452/4 "2017-07-12T18:59:16Z")

</div>

I think you are talking about this post : [LimeSDR minimum RX bandwidth via Soapy and GQRX?](https://discourse.myriadrf.org/t/limesdr-minimum-rx-bandwidth-via-soapy-and-gqrx/1176)

Unfortunately, the person didn’t get an answer…

I could maybe reduce the noise floor with GnuRadio if I insert a bandpass filter before doing the FFT.