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WL1837MOD: Outdoor Mesh Output Power

Mark Ackerson
Genius 10190 points
Part Number: WL1837MOD

Customer is building an outdoor mesh network system.  In doing so, they need to maximize range and ensure they use technology optimized for this purpose (vs designs that are optimized for phone/handheld/consumer).

We are having trouble confirming that the WiLink8 can transmit at the full FCC output power for outdoor radiators.  Irrespective of retaining FCC certifications, they need to select a WiFi platform that is able to transmit at full FCC power.  The values in the datasheet are "typical" values, but no information is present that indicates the radio can be calibrated to operate at much higher dBm values.

Please advise.

Regards,
Mark

  • 0
    TI__Genius 10550 points

    Hi Mark, 

    The numbers in the data sheet are the typical max TX power levels that the device can transmit while withstanding the IEEE spec (EVM and mask).

    On top of the DS numbers there are further power regulatory restrictions.

    Hope this helps.

    Regards, 

    Sudharshan K N

  • 0 in reply to Sudharshan KN
    TI__Expert 3520 points

    Hi Sudharshan,

    Thank you for the clarification regarding maximum TX power levels.

    For this specific application, the customer is strictly focused on maximizing range as mentioned and as a result will likely focus on a fixed modulation with low bitrate and are currently leaning towards the 11b CCK modulation within the US only (negating the ETSI restrictions specified in the datasheet note 2 regarding 16dBm 11B limits).

    Can you confirm what the IEEE specification allows for this modulation in comparison to the 30dBm FCC limit? From what I could find, the IEEE mask defines -30 dB at +/-11MHz from channel center frequency, but no other decrease in transmit limits.

    Since ETSI limits no longer apply, is it safe to operate at the 17.3dBm typical value for CCK and how does 17.3dBm compare to the relevant IEEE/FCC limits?

    Finally, the customer is willing to be in charge of conducting certification. Assuming the FCC/IEEE limits are higher than what the WiLink device can go to, are there any front-ends which you are aware of being used with WL18xx in the past which auto-detect TX/RX transitions?

    Best Regards,

    Mark-

  • 0 in reply to Mark Swanson
    TI__Genius 12740 points

    Hi Mark,

    You are correct in that the FCC limit is 30dBm (1W) for transmit power. However our radio output power is limited to ~20dBm, thus we would not be able to achieve the higher output power. Since the 2.4GHz only has a single output pin, it is also not possible to add and external PA to get better power as this is the RX/TX pin. Our current .INI file is a superset of all the regulator domains. That is since we use a single .INI file, the output power limit is going to be set for the lower of FCC/CE. Having said that, the 11b rates are limited for CE by the 10dBm/MHz limit, so if you were to have a radio that is FCC only, there you may be able to tweak the .INI file to gain 1-2dB more output power, but not close tot he 1W limit as our PA is not capable of this output power.

    I hope this helps.

    Thanks,

    Riz