# LimeUtil Calibration fails at certain frequencies and path combinations

**URL:** <https://discourse.myriadrf.org/t/limeutil-calibration-fails-at-certain-frequencies-and-path-combinations/5254>\
**Category:** System Development\
**Created:** [14 October 2019 12:44 UTC](https://discourse.myriadrf.org/t/limeutil-calibration-fails-at-certain-frequencies-and-path-combinations/5254 "2019-10-14T12:44:14Z")\
**Posts on this page:** 15\
**Page:** 1

<div class="post-metadata">

**Author:** ![kishores](https://avatars.discourse-cdn.com/v4/letter/k/9f8e36/32.png) [@kishores](https://discourse.myriadrf.org/u/kishores)\
**Post date:** [14 October 2019 12:44 UTC](https://discourse.myriadrf.org/t/limeutil-calibration-fails-at-certain-frequencies-and-path-combinations/5254/1 "2019-10-14T12:44:14Z")

</div>

Hi guys,  
I am using LimeUtil to calibrate my custom board based on LMS7002M LimeSuite library modified for SPI connection . Firstly,I have made following modifications to LimeUtilCalSweep.c.  
a) Changed the reciever path to LNAH in Rx and changed the transmitter path to Band2 in Tx .  
b) Set the reference frequency to 40MHz .  
c) Replaced LMS\_SetLOFrequency to LMS\_SetClockFreq  
I get the following **errors** -  
a) MCU calibration fails for Channel A , Channel B RX and Channel A TX.(Signal too weak or not connected) . It only passes for Channel B TX .  
**EDIT:There was a problem with channel configuration . Now it fails for RX path LNAH for both Channel A and B.**

What could be the reason for this strange behaviour ?

---

<div class="post-metadata">

**Author:** ![kishores](https://avatars.discourse-cdn.com/v4/letter/k/9f8e36/32.png) [@kishores](https://discourse.myriadrf.org/u/kishores)\
**Post date:** [15 October 2019 06:12 UTC](https://discourse.myriadrf.org/t/limeutil-calibration-fails-at-certain-frequencies-and-path-combinations/5254/2 "2019-10-15T06:12:55Z")

</div>

Hi , I just found something .  
[LNAH calibration](https://github.com/myriadrf/pyLMS7002M/blob/b866deea1f05dba44c9ed1a1a4666352b811b66b/cyLimeLib/win/LimeSuite.h#L433) .  
This tells that LNAH cannot be used for automatic calibration . Is this true for LimeSuite in general?

---

<div class="post-metadata">

**Author:** ![Zack](https://yyz2.discourse-cdn.com/flex034/user_avatar/discourse.myriadrf.org/zack/32/89_2.png) [@Zack](https://discourse.myriadrf.org/u/Zack)\
**Post date:** [15 October 2019 06:42 UTC](https://discourse.myriadrf.org/t/limeutil-calibration-fails-at-certain-frequencies-and-path-combinations/5254/3 "2019-10-15T06:42:29Z")

</div>

Hi @kishores,

> [@kishores](#):
>
> Changed the reciever path to LNAH in Rx and changed the transmitter path to Band2 in Tx .

Here is no loopback path to LNAH from Tx Band2 inside of LMS7002M. You can have these combinations:

1. Tx Band1 to LNAH;
2. Tx Band1 to LNAW;
3. Tx Band2 to LNAL.

Check [Programming and Calibration Guide](https://github.com/myriadrf/LMS7002M-docs/blob/master/LMS7002M_Programming_and_Calibration_Guide_v31r05.pdf), sections “RFE Control Diagrams” and “TRF Control Diagrams” for more information.

---

<div class="post-metadata">

**Author:** ![kishores](https://avatars.discourse-cdn.com/v4/letter/k/9f8e36/32.png) [@kishores](https://discourse.myriadrf.org/u/kishores)\
**Post date:** [15 October 2019 07:36 UTC](https://discourse.myriadrf.org/t/limeutil-calibration-fails-at-certain-frequencies-and-path-combinations/5254/5 "2019-10-15T07:36:28Z")

</div>

Hi @Zack, I am trying to calibrate over frequencies 2.2GHz to 2.3GHz . LNAH is not working with any combination with Band1 in this range . What should I look into at this point ?

---

<div class="post-metadata">

**Author:** ![Zack](https://yyz2.discourse-cdn.com/flex034/user_avatar/discourse.myriadrf.org/zack/32/89_2.png) [@Zack](https://discourse.myriadrf.org/u/Zack)\
**Post date:** [15 October 2019 07:46 UTC](https://discourse.myriadrf.org/t/limeutil-calibration-fails-at-certain-frequencies-and-path-combinations/5254/6 "2019-10-15T07:46:18Z")

</div>

Hi @kishores,

Do you have a possibility to save register values in LimeSuite format?

---

<div class="post-metadata">

**Author:** ![kishores](https://avatars.discourse-cdn.com/v4/letter/k/9f8e36/32.png) [@kishores](https://discourse.myriadrf.org/u/kishores)\
**Post date:** [15 October 2019 07:54 UTC](https://discourse.myriadrf.org/t/limeutil-calibration-fails-at-certain-frequencies-and-path-combinations/5254/7 "2019-10-15T07:54:42Z")

</div>

@Zack , [Link to config file](https://raw.githubusercontent.com/ApexPlus-Tech/Testing/master/RFD_number%3D1 __Date%3D15_10_2019__ 13_19_2.txt) . This is the configuration of registers . I think you would have to remove last 3 lines if you have to upload it

---

<div class="post-metadata">

**Author:** ![Zack](https://yyz2.discourse-cdn.com/flex034/user_avatar/discourse.myriadrf.org/zack/32/89_2.png) [@Zack](https://discourse.myriadrf.org/u/Zack)\
**Post date:** [15 October 2019 08:11 UTC](https://discourse.myriadrf.org/t/limeutil-calibration-fails-at-certain-frequencies-and-path-combinations/5254/8 "2019-10-15T08:11:37Z")

</div>

Do you use the same frequency for Tx LO and Rx LO?  
You use internal LDOs. Is this intended?

---

<div class="post-metadata">

**Author:** ![kishores](https://avatars.discourse-cdn.com/v4/letter/k/9f8e36/32.png) [@kishores](https://discourse.myriadrf.org/u/kishores)\
**Post date:** [15 October 2019 08:27 UTC](https://discourse.myriadrf.org/t/limeutil-calibration-fails-at-certain-frequencies-and-path-combinations/5254/9 "2019-10-15T08:27:37Z")

</div>

@Zack

> Do you use the same frequency for Tx LO and Rx LO?

Yes, I used same frequency for TXLO and RXLO .

> You use internal LDOs . Is this intended?

```
Yes, I am using internal LDOs . Could that be the issue ?

```

Another question,  
Is SXR and RX\_LO the same or different ?

---

<div class="post-metadata">

**Author:** ![Zack](https://yyz2.discourse-cdn.com/flex034/user_avatar/discourse.myriadrf.org/zack/32/89_2.png) [@Zack](https://discourse.myriadrf.org/u/Zack)\
**Post date:** [15 October 2019 08:47 UTC](https://discourse.myriadrf.org/t/limeutil-calibration-fails-at-certain-frequencies-and-path-combinations/5254/10 "2019-10-15T08:47:12Z")

</div>

> [@kishores](#):
>
> Yes, I used same frequency for TXLO and RXLO .

Then use SXT only:

1. Uncheck “LO buffer from SXT to SXR” in SXT tab in “Power down controls” group;
2. Check “VCO” in SXR tab in “Power down controls” group.

> [@kishores](#):
>
> Yes, I am using internal LDOs . Could that be the issue ?

No, just want to be sure you are not using these together with external ones.

> [@kishores](#):
>
> Is SXR and RX\_LO the same or different ?

These are the same.

---

<div class="post-metadata">

**Author:** ![kishores](https://avatars.discourse-cdn.com/v4/letter/k/9f8e36/32.png) [@kishores](https://discourse.myriadrf.org/u/kishores)\
**Post date:** [15 October 2019 11:51 UTC](https://discourse.myriadrf.org/t/limeutil-calibration-fails-at-certain-frequencies-and-path-combinations/5254/11 "2019-10-15T11:51:44Z")

</div>

@Zack , I am using LimeSuite library on headless server and hence my system has no GUI . I tried your suggestions by writing directly to the LMS register . I am using the function LMS\_WriteLMSReg(device,0x011C,0xA943) .  
Meanwhile, I tried with other start and stop frequencies(400MHz to 500Mhz). The result is the same . It always fails for the combination LNAH , Band1 .

---

<div class="post-metadata">

**Author:** ![kishores](https://avatars.discourse-cdn.com/v4/letter/k/9f8e36/32.png) [@kishores](https://discourse.myriadrf.org/u/kishores)\
**Post date:** [16 October 2019 08:09 UTC](https://discourse.myriadrf.org/t/limeutil-calibration-fails-at-certain-frequencies-and-path-combinations/5254/12 "2019-10-16T08:09:43Z")

</div>

Hi @Zack ,  
Sorry to disturb you but could you provide some input on this issue .

> Meanwhile, I tried with other start and stop frequencies(400MHz to 500Mhz). The result is the same . Calibration always fails for the combination LNAH , Band1 .

---

<div class="post-metadata">

**Author:** ![Zack](https://yyz2.discourse-cdn.com/flex034/user_avatar/discourse.myriadrf.org/zack/32/89_2.png) [@Zack](https://discourse.myriadrf.org/u/Zack)\
**Post date:** [16 October 2019 11:14 UTC](https://discourse.myriadrf.org/t/limeutil-calibration-fails-at-certain-frequencies-and-path-combinations/5254/13 "2019-10-16T11:14:46Z")

</div>

Hi @kishores,

We tried your configuration file on LimeSDR-Mini and it works fine. Probably there is an issue in your hardware.

---

<div class="post-metadata">

**Author:** ![kishores](https://avatars.discourse-cdn.com/v4/letter/k/9f8e36/32.png) [@kishores](https://discourse.myriadrf.org/u/kishores)\
**Post date:** [16 October 2019 12:37 UTC](https://discourse.myriadrf.org/t/limeutil-calibration-fails-at-certain-frequencies-and-path-combinations/5254/14 "2019-10-16T12:37:33Z")

</div>

Thanks @Zack for your reply . What could be the issue though ? If the clock is not exactly 40MHz could that cause problems ?

---

<div class="post-metadata">

**Author:** ![kishores](https://avatars.discourse-cdn.com/v4/letter/k/9f8e36/32.png) [@kishores](https://discourse.myriadrf.org/u/kishores)\
**Post date:** [17 October 2019 04:48 UTC](https://discourse.myriadrf.org/t/limeutil-calibration-fails-at-certain-frequencies-and-path-combinations/5254/15 "2019-10-17T04:48:43Z")

</div>

Hi @Zack,  
The hardware is quite similar to Lime Mini . We are able to do most of the things but calibration for LNAH is crucial .  
I can send you the schematics and PCB design files if you want them in your personal mail .

---

<div class="post-metadata">

**Author:** ![Zack](https://yyz2.discourse-cdn.com/flex034/user_avatar/discourse.myriadrf.org/zack/32/89_2.png) [@Zack](https://discourse.myriadrf.org/u/Zack)\
**Post date:** [17 October 2019 05:15 UTC](https://discourse.myriadrf.org/t/limeutil-calibration-fails-at-certain-frequencies-and-path-combinations/5254/16 "2019-10-17T05:15:12Z")

</div>

Hi @kishores,

OK, send schematics via PM, please.