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AWR1843AOP: AWR1843AOP CE Compliance Question

Bernard Wiwel
Prodigy 50 points

Part Number: AWR1843AOP
Other Parts Discussed in Thread: AWR1843BOOST

We are looking for help to answer some questions regarding CE certification of the AWR1843AOP.

 

We were able to locate a CE test report (standard 302 264 v2.1.1) that TI issued for the AWR1843BOOST.  This is the same test that we are looking to apply in our own testing.

 

We have a few questions about how some of the tests and numbers were arrived in this report that would help us to understand how to best put together a test plan for circuit designs utilizing this part.

 

The main issue we have is measurement of the out-of-band emissions (OOB), and defining the upper and lower OOB frequencies fL and fH required in that specification.  Section 7.2 of the TI report (attached for reference) seems to show an alternative method being used that determines fL and fH as the -23dBc band width.

 

TI REPORT:

 

 

The ETSI EN 303 396 test standard (attached for reference and to which the EN 302 264 standard refers) on the other hand talks about determination of fL and fH from the 99% occupied band width function (OBW), but in our current testing this results in a band edge power that will fail the specification.  We would like to apply the -23dBc approach used in the TI report, but how/where does TI find the EN standard to allow for this?

 

EN 303 396 Test Standard:

 

Additionally, the out-of-band power (OOB) levels taken in section 7.5 of the TI report show a Duty Cycle Correction factor being added to the OOB RMS mean power spectral density measurement.  This seems incorrect as the analyzer measurement should have already provided the mean RMS value over the transmission frame.  Applying the correction factor appears to be removing the averaging over the frames and actually penalizes the result by making it higher than necessary.  Despite what appears to be an unnecessary penalty, the TI result however still passes the test limit.

 

TI REPORT:

 

 

The ETSI EN 303 396 test standard appears to state that the mean power spectral density is to be measured with a an RMS detector and averaged for a time greater the one EUT cycle time.  In the TI test result, the sweep time setting appears to be averaging over 5 bursts for each sweep point, so I would think that result (the Corr Meas dBm/MHz EIRP, before adding any duty cycle correction) alone should be sufficient to provide the measurement of the mean power spectral density as the specification requires.  Why does the TI report further add a duty cycle correction factor to this increasing the reported OOB value above the averaged result the analyzer is already providing?

 

EN 303 396 Test Standard:

 

 

We appreciate any feedback on this.

 

en_302264v020101p.pdf 

TI RED en_302_264_test_report.pdf

en_303396v010101p.pdf 

 

Regards,

Bernard

 

 

 

  • 0
    TI__Genius 16466 points

    Hey Bernard,

    Thanks for reaching out regarding CE certifications. Our emissions experts our currently on holiday, but they should return by the end of the week. Please give us until the end of the week or the start of next week to respond.

    Thank you for your patience,

    Kristien

  • 0
    TI__Prodigy 70 points

    Kristien, Can someone answer our customer please?

  • 0 in reply to Kristien Everett
    TI__Prodigy 70 points

    Kristien, Can someone answer our customer please?

  • 0 in reply to Kawtar BERKOUK
    TI__Expert 4850 points

    Hi Bernard,
                    Apologies for the delay. I was out in the last week and trying to catch-up things.

    1. Yes, the ETSI standard mentions 99% OBW to determine the FL and FH frequency values. But for the FMCW modulation, spectral skirts can extend beyond 99%OBW or in other words you cannot expect a sharp roll-off. This is unrealistic for FMCW modulation. What we've been told by the test house is "The –23 dBc Relative Bandwidth is a widely accepted method to measure the Emission Bandwidth of a device". Thus, the measurements were made with -23dBc method.
    2. The correction factor shouldn't be used in the OOB emissions as there is no intentional radiators radiating in those frequencies with any specific duty cycles. I have to check this internally once on why this was used while drafting the report.

    Please let us know if you have any further questions on this topic.

  • 0 in reply to Kundan Somala
    Prodigy 50 points

    Thankyou Kundan,

    This has been very helpful and puts us in a pretty good position to move forward.

    One further detail that would be helpful is understanding if the -23dBc number is something fixed in stone somewhere or if it is a more general approach that we can use to simply declare how much band width our signal is intended to occupy. 

    For instance, could this approach be extended to a -28dBc band width or something more?

    In other words, would it be acceptable to alternatively define the band edge as a -XdBc bandwidth where X is large enough that the skirt is just below the OOB limit at the -XdBc band edges?

    I mention this as a way to allow for maximal use of in-band transmit power that would also end up raising the skirt levels, and thus effectively also increase the amount of occupied band width needed to pass the out of band limits, provided of course that the band width stays within the permissible frequency range of the specification.

  • 0 in reply to Bernard Wiwel
    TI__Expert 4850 points

    Hi Bernard,

    I am not 100% sure if there is a specific clause that defines the -23dBc number. I believe this is a measurement standard/procedure followed by test houses in general. I can try reaching out to our test house if they have any documentation in the web which can help you.

    Thanks,
    Kundan