Transcript Licensed vs. Unlicensed Devices

• They are not the same
• Dennis Ward
• ATCB
• The FCC has a requirement that Applications for
certification through the TCB program must contain
test reports that CLEARLY show testing was
performed in accordance with established approved
FCC procedures.
• The FCC has recently shown concern that proper test
procedures and methods are not being done or
followed.
• Procedures for Licensed and unlicensed devices are
not the same.
• Some devices do not have established procedures.
• A lab may be proficient in part 15 unlicensed
intentional radiators but this does not mean
the lab is proficient in testing licensed
transmitters.
• The same may be true the other way round.
• The lab should thoroughly understand the
rule part, test methods and procedures it will
be using.
• The lab must also clearly identify these
established procedures in the test report.
– Typically the approved procedure is to be referenced in the
report and subsequent test methods clearly stated for each test
type.
• Power, radiated emissions, conducted antenna terminal, occupied
bandwidth each should provide clear and related test methodology in
accordance with the approved standard.
• Typically for licensed devices this is TIA603C.
• Most part 15 devices use ANSI C63.4 2003.
• 15.247, 15.407 and others for example are not tested to ANSI C63.4.
The Obvious differences
• Test procedures and requirements for the licensed
world include:
– A world of power
– A world of modulation
– A world of protected services
• The test procedures and requirements for the
unlicensed world include:
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With a few exceptions a world of field strength.
Has no protection for an unlicensed transmitter.
Not allowed to interfere with a licensed service.
Subject to many restrictions.
Testing Differences
• The licensed world of TIA603
– Licensed devices are devices whose outputs are
conducted power at the antenna terminal or
ERP/EIRP oriented.
• Antenna terminal conducted power measurements for
devices with removable antennae.
• ERP/EIRP measurements in accordance with TIA603
(not reverse calculated field strengths) for devices with
non-removable antennae.
• Because of higher power levels and modulation
measurement requirements, labs must have appropriate
test equipment (appropriate attenuators etc).
• Labs must be well versed in TIA603 as well as the use of
this specialized equipment.
Testing Differences contd
– Modulation must be appropriate for the
licensed service.
• Labs must have and be able to adequately use
appropriate modulation analyzers, base station
simulators, etc. to analyze the modulation
characteristics of the transmitter.
• Emissions designators must be adequately
addressed.
• Lab personnel must be able to determine
proper emissions designators
Testing Differences contd
– Measurement techniques are generally well defined by TIA
(TIA 603-C 2004).
– The lab must be very familiar with the licensed device test
methods under this standard and must be able to determine
what test procedure is appropriate.
– The lab must be able to associate what test methods do or
do not apply and when 47CFR stipulations take precedence.
– Labs must follow the applicable portions of TIA603 dealing
with the device tested.
– Labs must know when TIA603 does not apply and where
(i.e. how or where does TIA603 apply to part 90Y, part 27
AWS etc)
Testing Differences contd
– The lab must understand and be able to perform proper
testing in accordance with TIA603 for:
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Conducted antenna carrier output.
Temperature and voltage frequency stability.
Modulation limiting.
Carrier attack time and transient frequency behavior.
Adjacent channel power.
Audio sensitivity, distortion and frequency response.
Audio low pass filter response
Intermodulation
Antenna substitution measurements.
– The FCC requires this to be a measured value and not a
calculated equivalent field strength.
– Example - What methods from TIA 603 apply to the transmitter
fundamental and which apply to the spurious.
– The lab must know and understand the difference.
• The lab must finally adequately explain how and why a
particular test was performed and include this explanation in
the test report.
Testing Differences contd
• The unlicensed world
– Testing is done in strict accordance with approved
test procedures.
– As applicable, testing is also done in accordance
with ANSI C63.4
– Testing is done on a approved OATS (except for
antenna term measurements).
• Labs that are only listed on the FCC site are not exempt
from establishing/showing confidence in their ability to
test.
• Labs accredited and shown on the FCC site, while
having a presumption of competence, must/should still
establish/show confidence in their ability to test.
Testing Differences contd
• The lab must understand, be able to perform and show
competence in proper testing in accordance with ANSI C63.4
and any specific intentional radiator test procedures including:
– DA000705 FHSS systems.
– Measurement of Digital Transmission Systems Operating under
Section 15.247(3-2005).
– mm wave devices
• The lab must understand how to convert field strength levels to
ERP/EIRP.
– Unlike the licensed world, this can be a calculated ERP.
– The lab can use measured ERP instead of calculated for the
unlicensed world – but not the other way round)
• The lab must understand and know how to incorporate
appropriate Pulse Desensitization techniques when necessary.
– HP/Agilent Technical note 150 is a good start.
The lab must clearly explain how testing performed.
Questions