RT and Response

FCC ID: RI7WE865D

Cover Letter(s)

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FCCID_1022528

Jenn Warnell

From: Sara González López [sgonzalez@at4wireless.com]
Sent: Friday, October 17, 2008 6:30 AM
To: Jennifer Sanchez
Cc: Jenn Warnell
Subject: RE: 81201 AT4 Wireless - Request for Technical Information
Importance: High
Attachments: RT 15 Oct 2008.pdf; Freq Hopper Guidelines.PDF; Direct Sequence Measurment Notes.pdf;
RE: 81201 AT4 Wireless - Request for Technical Information

Hello,

1. Regarding the output power, in point 15.247 (b) (3) it is specified:

“For systems using digital modulation in the 902-928 MHz, 2400-2483.5 MHz, and 5725-5850 MHz bands: 1
Watt. As an alternative to a peak power measurement, compliance with the one Watt limit can be based on
a measurement of the maximum conducted output power. Maximum Conducted Output Power is defined
as the total transmit power delivered to all antennas and antenna elements averaged across all symbols in
the signaling alphabet when the transmitter is operating at its maximum power control level. Power must be
summed across all antennas and antenna elements. The average must not include any time intervals during which
the transmitter is off or is transmitting at a reduced power level. If multiple modes of operation are possible (e.g.,
alternative modulation methods), the maximum conducted output power is the highest total transmit power
occurring in any mode”.

In test report 28057RET.101 page 15 it is clearly indicated that this permitted alternative method to a peak power
measurement was used, so we believed the measurement is correct.

2. Regarding the conducted band edge plots, it is specified in point 15.247 (d):
“If the transmitter complies with the conducted power limits based on the use of RMS averaging over a time
interval, as permitted under paragraph (b)(3) of this section, the attenuation required under this paragraph shall be
30 dB instead of 20 dB”.

In test report 28057RET.101 pages 22, 23 and 24 it is shown in the plots that we applied the limit of 30 dB. This is
because the output conducted power was measured using RMS averaging over a time interval, as indicated
previously.

The reason of use of a RBW different from 100 kHz is that as there is no measurement guideline for conducted
band-edge compliance neither in point 15.247 nor in document “ Appendix C Guidance on Measurement for
Direct Sequence Spread Spectrum Systems” (see attached) we followed the document DA 00-705 released
March 30, 2000 “ Filing and Measurement Guidelines for Frequency Hopping Spread Spectrum Sytems” (see
attached) as we always did in previous accepted reports of part 15.247 which we submitted in the past.
In such document it is indicated in “Section 15.247 (c) . Band-edge compliance of RF Conducted Emissions” the
use of a RBW ≥ 1% of the span.

3. Regarding compliance of radiated emissions in the 15.205 restricted bands, in test report 28057RET.101 pages
30, 31 and 43 it is clearly indicated that no spurious signals were found in such restricted bands, which were
investigated searching for spurious signals. No plots of these bands were added besides the wide range plots we
always included in previous accepted reports of part 15.247 which we submitted in the past.
If you consider it is necessary to include such plots please confirm and we will include in future 15.247 test
reports.

10/17/2008

Document Created: 2008-10-28 15:25:00
Document Modified: 2008-10-28 15:25:00

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