STPXS8 GSM/GPRS/EDGE/CDMA/UMTS/HSPA Module RF Exposure Info Low Duty Cycle Analysis Satellite Tracking of People LLC

Satellite Tracking of People LLC GSM/GPRS/EDGE/CDMA/UMTS/HSPA Module

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Upper Bound Transmission Duty Factor Analysis for FCC: S5ESTPXS8
SoberTrack is primarily a handheld alcohol detection device used to perform several regularly scheduled
or random sobriety tests on the user. The device includes a camera which is used to take still and/or
video images of the user whilst performing the sobriety test. The pictures and test results are sent back
to a central gateway using GSM / CDMA wireless networks once the tests have been completed.
Additionally, video may be saved to an SD card. Voice operations are not supported.
The Device uses the PXS8 multimode cellular module, FCC ID S5ESTPXS8, to transmit data or alarms via
the cellular wireless network. The device also supports a 915 low power (<10mW, FCC Part 15C)
transmitter, a GPS receiver and a Murata WiFi module that is used in a receive‐only mode and does not
transmit. The device firmware ensures that the cellular module and the 915 MHZ transmitter will never
transmit simultaneously.
The SoberTrack will be certified under FCC ID S5EST10417 to cover the 915 MHz transceiver. FCC
approvals for the cellular operations will be covered by the modular approval for FCC ID S5ESTPXS8. As
the full modular approval is limited to mobile devices a Class II Permissive Change will be submitted to
cover use of the module in a portable rf exposure condition in the SoberTrack. Based on the duty cycle
analysis in this document, the time‐averaged output power levels for the module are below the
thresholds that would require SAR testing for a portable device used within 5mm of the body or head.
The main SoberTrack application processor controls the operation of the modem. In the event of a
connection not being established the SoberTrack device will store the data and retry at 5 minute
intervals.
The SoberTrack is by default programmed to transmit sobriety results via cellular data message every
300 seconds lasting typically 2‐3 seconds. In a worst‐case scenario with latency this could be increased
to a maximum transmission lasting 6 seconds every 300 seconds. In the event of latency exceeding 6s
the device will terminate the call and retry in the next 5‐minute cycle.
The correction of average output power for duty cycle is thus 6/300*maximum power. The tables in the
following section show the maximum rated power, including tune up tolerance for each of the
technologies and operating bands supported in the USA by the module. Those power values are
corrected for source based duty cycle (i.e. GSM frame power) and then corrected for the 6/300
operational duty cycle and the resulting power levels are used to determine the SAR exclusion
requirements based on KDB 447498.
Supported Cellular technologies and maximum power including tune‐up tolerance.
Technology/Band
Maximum Power
(dBm)
24.5
24.5
24.5
24.5
W‐CDMA II
W‐CDMA V
CDMA BC0
CDMA BC1
RF Air
Interface
Tx 1 Slot
Maximum
Maximum
Power
Power
(dBm)
(mW)
GSM 850
GSM 1900
RF Air
Interface
GSM 850
GSM 1900
33.5
30.5
GPRS/EGPRS
Tx 2 Slots
Tx 3 Slots
Maximum
Maximum
Maximum
Maximum
Power
Power
Power
Power
(dBm)
(mW)
(dBm)
(mW)
2239
1122
Tx 1 Slot
Maximum
Maximum
Burst Power
Frame
(mW)
power
(mW)
2239
282
1122
141
Maximum Power
(mW)
282
282
282
282
30.5
27.5
1122
562
Tx 2 Slots
Maximum
Maximum
Burst
Frame
Power
power
(mW)
(mW)
1122
282
562
141
28.7
25.7
741
372
Tx 3 Slots
Maximum
Maximum
Burst
Frame
Power
power
(mW)
(mW)
741
278
372
140
Tx 4 Slots
Maximum Maximum
Power
Power
(dBm)
(mW)
27.5
24.5
Tx 4 Slots
Maximum
Maximum
Burst
Frame
Power
power
(mW)
(mW)
562
281
282
141
Duty Cycle correction
Technology/Band
W‐CDMA II
W‐CDMA V
CDMA BC0
CDMA BC1
GSM850
GSM1900
Upper Frequency
(MHz)
1907.6
846.6
849
1910
849
1910
Maximum Power
(mW) without duty
factor correction
(mW)
282
282
282
282
282
141
562
282
Maximum Power
(mW) with duty
factor correction
(mW)
5.6
5.6
5.6
5.6
5.6
2.8
SAR Exclusion Calculations
From KDB 447498, for transmission frequencies 100 MHz to 6 GHz and test separation distances ≤ 50
mm, the 1‐g SAR test exclusion thresholds are determined by the following:
[(max. power of channel, including tune‐up tolerance, mW) / (min. test separation distance, mm)] ∙
[√f(GHz)] ≤ 3.0 where:



f(GHz) is the RF channel transmit frequency in GHz;
Power and distance are rounded to the nearest mW and mm before calculation;
For a separation distance of less than 5mm, 5mm is used.
The result is rounded to one decimal place for comparison with the 3.0 threshold.
The table below shows that at the maximum power for all bands and technologies, after accounting for
source‐based and operational duty cycles, and for a separation distance of 5mm or less, SAR test
exclusion applies.
Max. tune-up
tolerance
(mW)
Min. test
separation
distance (mm)
SAR test
exclusion
Result*
0.191
0.5
1.1
1.1
Body-w orn
0.847
0.855
0.191
0.5
GSM850
Body-w orn
0.849
1.1
GSM1900
Body-w orn
0.191
0.3
RF Exposure
Conditions
Frequency
(GHz)
W-CDMA II
Body-w orn
W-CDMA V
CDMA BC0, BC10
CDMA BC1
Body-w orn
Body-w orn
RF Air interface
Conclusion:
*: The computed value is ≤ 3; therefore, this qualifies for SAR test exclusion.
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Document ID3401676
Application ID2geVwrmuQwg3eP4PCSem5A==
Document DescriptionLow Duty Cycle Analysis
Short Term ConfidentialNo
Permanent ConfidentialNo
SupercedeNo
Document TypeRF Exposure Info
Display FormatAdobe Acrobat PDF - pdf
Filesize8.31kB (103837 bits)
Date Submitted2017-05-24 00:00:00
Date Available2017-05-26 00:00:00
Creation Date2017-05-23 07:18:15
Producing SoftwareAcrobat Distiller 15.0 (Windows)
Document Lastmod2017-05-23 07:18:15
Document TitleLow Duty Cycle Analysis
Document CreatorPScript5.dll Version 5.2.2
Document Author: 31256

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