IWR1843AOP: FCC Issues

Timothy Christensen

Part Number: IWR1843AOP
Other Parts Discussed in Thread: AWR1843

Tool/software:

I have completed a product printed circuit board and currently testing to meet FCC. There is a spurious emission at 28.8GHz that is 2.5dB above threshold. I have changed RTRIM to 6 per other comments in this forum. It only slightly reduced the emission by 1 dB on one unit and 0.25 dB on a second sample. The FCC guide published by TI states that the RTRIM and 28.8GHz spur is only with the non-AOP. Please help provide a solution to try to reduce the 28.8GHz emission.

2 months ago

0 Ankit Mohanty 2 months ago

TI__Genius 9710 points

Hi Timothy,

Please allow us 24 hours' time; one the expert shall get back to you soon.

Regards

Ankit

0 Blake Kisshauer 2 months ago in reply to Ankit Mohanty

TI__Expert 4360 points

Timothy,

You should be able to reduce the APLL emissions by duty-cylcing the APLL. This is described in 4.2.3 of this app note: https://www.ti.com/lit/an/swra689/swra689.pdf

The particular call is rlSsetPowerSaveModeConfig.

The goal here is to reduce the spurious emission by reducing the on-time of the APLL.

Thanks!

Blake

0 Timothy Christensen 2 months ago in reply to Blake Kisshauer

Prodigy 30 points

Hello Blake,

thank you for this information. I am reviewing the document and code regarding the power save mode call. Some additional help would be appreciated. To get the maximum advantage of toggling the APLL and max reduction of 28.8GHz spur, is there any example code or could you point to the best place in AWR1843 OOB code where and how this call should be inserted. Thank you

0 Blake Kisshauer 2 months ago in reply to Timothy Christensen

TI__Expert 4360 points

Timothy,

There is not an 1843AOP example, however there is one for 6843. You can use this as an example for 1843AOP since the 6843 and 1843 familes share the same digital cores.

https://dev.ti.com/tirex/explore/node?node=A__AOJjAWsYPq56ZxKYYyJH5A__radar_toolbox__1AslXXD__LATEST

I hope this helps!

Thanks!

Blake

0 Timothy Christensen 2 months ago in reply to Blake Kisshauer

Prodigy 30 points

Hi Blake, I have run the example code on an xWR6843AOP eval card and it appears the code is working. Since I am using a xWR1843, I tried to import the routines in my cli and mss.main code. I am getting errors for

undefined first referenced
symbol in file
--------- ----------------
xWR6843_dss_clock_gate ./mss_main.oer4f
xWR6843_dss_clock_ungate ./mss_main.oer4f
xWR6843_mss_vclk_200M ./mss_main.oer4f
xWR6843_mss_vclk_40M ./mss_main.oer4f

I can see that these are in a 6843 libsleep library, are there 1843 equivalent files or libraries I can use to solve this issue?

0 Blake Kisshauer 2 months ago in reply to Timothy Christensen

TI__Expert 4360 points

Timothy,

This may require a more detailed SW response than I am able to provide. I've asked a collgeague to respond to you. Please allow a few days for them to resond to this thread.

Thanks!

Blake

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IWR1843AOP: FCC Issues