# Strange/Missing Readings from LimeSDR Mini 2

**URL:** <https://discourse.myriadrf.org/t/strange-missing-readings-from-limesdr-mini-2/8531>\
**Category:** LimeSDR\
**Created:** [11 October 2024 20:39 UTC](https://discourse.myriadrf.org/t/strange-missing-readings-from-limesdr-mini-2/8531 "2024-10-11T20:39:25Z")\
**Posts on this page:** 8\
**Page:** 1

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**Author:** ![xinsong](https://avatars.discourse-cdn.com/v4/letter/x/edb3f5/32.png) [@xinsong](https://discourse.myriadrf.org/u/xinsong)\
**Post date:** [11 October 2024 20:39 UTC](https://discourse.myriadrf.org/t/strange-missing-readings-from-limesdr-mini-2/8531/1 "2024-10-11T20:39:25Z")

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Hi all, I am doing a course project that requires analyzing a wireless protocol. To get started, I tried sniffing the ambient wireless spectrum to see if my board and toolchain were working. The following sequence of experiments has led me to believe my board is defective, but I do not have enough experience to tell for sure.

1. I installed `LimeSuite` from `apt` on a `ubuntu 20.04` machine and used `QSpectrumAnalyzer` to record signals in the wifi range. This returned very low signal strengths in the low `-130db`’s. After turning up the gain, the best I could get was `-128db` or so.  
 **![](https://lh7-rt.googleusercontent.com/docsz/AD_4nXeNv8tAIaRBIYVehEt7GucGGqkfhwpcel_A2npdGm4UZmlrhQb_UZdsC281wa1_DRMRGZCamUslqg0Hp8KQQuseGcsYJpnfJ6HcPyCziyxv5GEqZFQQIv8UKR5QHAEqUi7OWcaYwtF7M3oeUrOOwtLIydEI?key=jpl_Ro4P0tUXiueg3flg6Q)**

2. Fine, so I thought, perhaps the radio needed calibration. But using `LimeSuiteGUI` to calibrate, I got intermittent errors. Sometimes the error was `RX Calibration Failed: MCU error 5 (Loopback signal weak: not connected/insufficient gain?)`. Other times it would be `RX Calibration Failed: MCU error 3 (SXR tune failed)`. And once in a while, the calibration would go through if I unplug/replug the device.

3. Finally, just for completeness, I also tried `Universal Radio Hacker` and it was not able to read from the board, albeit successfully opening the stream.

4. I also tried the above on a Mac to see if the errors were machine/OS dependent. Unfortunately, I got the same result. Any help is greatly appreciated!

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**Author:** ![Evan](https://avatars.discourse-cdn.com/v4/letter/e/54ee81/32.png) [@Evan](https://discourse.myriadrf.org/u/Evan)\
**Post date:** [11 October 2024 21:07 UTC](https://discourse.myriadrf.org/t/strange-missing-readings-from-limesdr-mini-2/8531/2 "2024-10-11T21:07:07Z")

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I have also seen these errors on my SDRs but they are fully functional. Had to spend some quality time with the ‘LMS7002M-Programming-and-Calibration-Guide-v31r05.pdf’ to figure it out.

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**Author:** ![xinsong](https://avatars.discourse-cdn.com/v4/letter/x/edb3f5/32.png) [@xinsong](https://discourse.myriadrf.org/u/xinsong)\
**Post date:** [11 October 2024 21:14 UTC](https://discourse.myriadrf.org/t/strange-missing-readings-from-limesdr-mini-2/8531/3 "2024-10-11T21:14:41Z")

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Hmm okay, thank you! Were you also seeing very low signal strengths and how were you able to fix it? Also, were you able to use `Universal Radio Hacker` with your LimeSDR?

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**Author:** ![Evan](https://avatars.discourse-cdn.com/v4/letter/e/54ee81/32.png) [@Evan](https://discourse.myriadrf.org/u/Evan)\
**Post date:** [11 October 2024 21:28 UTC](https://discourse.myriadrf.org/t/strange-missing-readings-from-limesdr-mini-2/8531/4 "2024-10-11T21:28:01Z")

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We wrote custom code to process the data but I think everything you need is in Lime Suite. The FFT viewer will display the real time data. Every tab is important and worth reviewing their function but items to look at specifically are:  
RFE tab:  
LNA\_RFE is powers up, Active path is LNAH, LNA gain at Gmax, TIA at Gmax  
RBB tab:  
PGA gain at +19

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**Author:** ![andrewback](https://avatars.discourse-cdn.com/v4/letter/a/22d042/32.png) [@andrewback](https://discourse.myriadrf.org/u/andrewback)\
**Post date:** [12 October 2024 11:24 UTC](https://discourse.myriadrf.org/t/strange-missing-readings-from-limesdr-mini-2/8531/5 "2024-10-12T11:24:41Z")

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> [@xinsong](#):
>
> `->LimeSuite version: 22.09.1-myriadrf1~ubuntu20.04`

You’re using a version of Lime Suite that pre-dates LimeSDR Mini v2 support IIRC. Would suggest installing the latest tagged release:

[Release v23.11.0 · myriadrf/LimeSuite · GitHub](https://github.com/myriadrf/LimeSuite/releases/tag/v23.11.0)

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<div class="post-metadata">

**Author:** ![xinsong](https://avatars.discourse-cdn.com/v4/letter/x/edb3f5/32.png) [@xinsong](https://discourse.myriadrf.org/u/xinsong)\
**Post date:** [13 October 2024 03:36 UTC](https://discourse.myriadrf.org/t/strange-missing-readings-from-limesdr-mini-2/8531/6 "2024-10-13T03:36:56Z")

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will try it thanks!

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<div class="post-metadata">

**Author:** ![xinsong](https://avatars.discourse-cdn.com/v4/letter/x/edb3f5/32.png) [@xinsong](https://discourse.myriadrf.org/u/xinsong)\
**Post date:** [14 October 2024 20:07 UTC](https://discourse.myriadrf.org/t/strange-missing-readings-from-limesdr-mini-2/8531/7 "2024-10-14T20:07:46Z")

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Okay so with the newer build, `LimeSelfTest` passed (seemed like certain checks were disabled and tolerances were changed with the new build).

That said, `QSpectrumAnalyzer` still showed low signal strength, and `Universal Radio Hacker` was still unable to read any data off the board.

One thing I found was that the FFT viewer in the LimeSuiteGUI did not draw anything after using either `QSpectrumAnalyzer` or `URH`. Upon closer inspection, the parameters in the tab `SXR`, `SXT`, and `CLKGEN` were all updated after using the two aforementioned software.

Now, after hitting the default button in LimeSuiteGUI, the FFT showed up properly.

 ![image-1](https://canada1.discourse-cdn.com/flex034/uploads/myriadrf/original/2X/2/262e1040e72c7e37fd9b23ee94d92293b3b62e5b.png)

Thus, it appears to me all problems boil down to the parameters these third-party software have set. I don’t see mini v2 as one of the supported boards on the `URH` github. Will do some search for compatible software. Thank you for all the replies!

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<div class="post-metadata">

**Author:** ![andrewback](https://avatars.discourse-cdn.com/v4/letter/a/22d042/32.png) [@andrewback](https://discourse.myriadrf.org/u/andrewback)\
**Post date:** [15 October 2024 13:14 UTC](https://discourse.myriadrf.org/t/strange-missing-readings-from-limesdr-mini-2/8531/8 "2024-10-15T13:14:22Z")

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> [@xinsong](#):
>
> (seemed like certain checks were disabled and tolerances were changed with the new build).

LimeSDR Mini v2 has some architectural differences to v1 and this includes loopback, which meant that the pass/fail values are different.