TCB Q&A Band 38 41 7 Test Report

FCC ID: A4RG020A

Test Report

Download: PDF
FCCID_4171907

From:            Briggs, Mark
To:              "joanna.hung@tw.bureauveritas.com"
Cc:              alberttsang@google.com; amanda.wu@tw.bureauveritas.com; andrea.hsia@tw.bureauveritas.com; Delisi, Bob;
                 celinacui@google.com; Harvey, Christopher; Hoque, Claire; Park, Daniel; darren.shih@tw.bureauveritas.com;
                 George He; hedyhsieh@google.com; Hsieh, Joe; Tsai, Lucy; rinhuang@google.com; sherryhylu@google.com;
                 timklee@google.com; Warwick Wong
Subject:         RE: Google LLC series of filings
Date:            Tuesday, January 29, 2019 3:23:00 PM


Dear Joanna

Thank you for all the responses to previous questions. As we discussed the Part 27 reports for bands
38/41/17 have not used the correct bandwidth when evaluating emissions more than 1MHz from
the block (channel) edge. Depending on the emission bandwidth, the report uses measurements
bandwidths of 100kHz, 200kHz, 300kHz or 500kHz at different offsets from the band edge.

Under Part 27 the reference bandwidth for measurements more than 1MHz from the channel edge
is 1MHz except for the 1 megahertz bands immediately outside and adjacent to the frequency block a
resolution bandwidth of at least two percent may be employed, except when the 1 megahertz band is
2495-2496 MHz, in which case a resolution bandwidth of at least one percent may be employed.

While the rules do allow for a narrower resolution bandwidth the measured power has to be
corrected / integrated over the full required measurement bandwidth (i.e. 1 megahertz or 2 percent
for mobile digital stations, except in the band 2495-2496 MHz). The correction factor to adjust a
measurement bandwidth of 100kHz (the narrowest bandwidth used) to a reference bandwidth of 1
MHz is 10 log (1 MHz / 100kHz) = +10dB (refer ANSI C63.26 section 4.2.3). Since all emissions
measured have a margin of at least 20dB without correction, and given that the worst case
correction factor to apply to the measured values would be +10dB, the data provided does
demonstrate that the device has at least a 10dB margin to the limits at the block / band edges.

This correspondence will be uploaded to the FCC filing for the PCE equipment code to ensure labs or
others reviewing the data understand that compliance has been demonstrated after accounting for
the appropriate bandwidth correction factors.

Best regards,

Mark

Mark Briggs
Director, Wireless Certification Services
UL Verification Services
Camas, WA

Mobile: 1-971-724-8832
Phone: 1-360-817-5531



Document Created: 2019-01-29 15:42:36
Document Modified: 2019-01-29 15:42:36

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