# Internal loopback test

**URL:** <https://discourse.myriadrf.org/t/internal-loopback-test/78>\
**Category:** Reference Development Kit\
**Created:** [19 March 2014 11:04 UTC](https://discourse.myriadrf.org/t/internal-loopback-test/78 "2014-03-19T11:04:01Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![mugilan\_july](https://avatars.discourse-cdn.com/v4/letter/m/57b2e6/32.png) [@mugilan\_july](https://discourse.myriadrf.org/u/mugilan_july)\
**Post date:** [19 March 2014 11:04 UTC](https://discourse.myriadrf.org/t/internal-loopback-test/78/1 "2014-03-19T11:04:01Z")

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hi ,  
We are using myriad rf in standalone mode using arduino for spi interface and we are using crystal oscillator of 25 MHz as pll ref clock. Register tests are fine. we have following queries regarding internal loop-back test in standalone mode:

1. In rf (internal) loop-back test, are there any precautions to be considered regarding RX LNA in receive path such as preventing LNA saturation ?

2. Is there any control for adjusting gain of AUXPA (Auxiliary PA) in ctr6002d application?

3. If we internally loop back with maximum gain from TX path to RX path (internally) are there any chances of damage to LMS6002D??

Thanks in advance.

Mugilan M

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**Author:** ![andrewhux](https://avatars.discourse-cdn.com/v4/letter/a/d07c76/32.png) [@andrewhux](https://discourse.myriadrf.org/u/andrewhux)\
**Post date:** [19 March 2014 18:22 UTC](https://discourse.myriadrf.org/t/internal-loopback-test/78/2 "2014-03-19T18:22:03Z")

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Hello Mugilan,

The RF LoopBack connects Tx path with Rx path after LNA. As you can see in this document:

[https://github.com/myriadrf/LMS6002D-docs/blob/master/LMS6002D%20IF-RF%20LoopBack%20Options.pdf](https://github.com/myriadrf/LMS6002D-docs/blob/master/LMS6002D%20IF-RF%20LoopBack%20Options.pdf)

Hence, there is not possible to saturate LNA. But it is possible to saturate LMS6002D ADC’s (not damage to chip) if max gain in TRX path is set to maximum.

According SPI programming guide, register 0x4C[3-0] controls AUXPA gain:  
[https://github.com/myriadrf/LMS6002D-docs/blob/master/LMS6002Dr2-Programming%20and%20Calibration%20Guide-1\_1r4.pdf](https://github.com/myriadrf/LMS6002D-docs/blob/master/LMS6002Dr2-Programming%20and%20Calibration%20Guide-1_1r4.pdf)

Andrew