6 © 2002 Motorola, Inc.
Personal Communications Sector
Product Description
T720
T720 W/AGPS
T720 is similar as V 120X in
functionality except that it also has the
Assisted Global Positioning System.
AGPS helps in 911 emergency calls to track
the user to its exact location.
Concept:
The phone receives the signals from GPS sat-
ellites(from 3 of 24 in the orbit), signals as low
as –149dB(typical is –130dB) and transmit the
information to the cell site in CDMA mode.
GPS service is available only with CDMA ser-
vice. No GPS operation in AMPS system.
GPS works on 1575.42Mhz frequency.
T720c is similar in electrical, mechanical
is diffrent to V120X except
as follows to support the AGPS:
— 30 new parts which contains discrete
components – resistors , capacitors, and
filters which are mostly at the front end of
the receiver.
— T720c also use the same RF antenna.
This is done by using a coupler between
the internal antenna and the AGPS
antenna.
— RF shield covers the front end receiver of
the GPS circuit.
— FM and GPS share the lines at the back end
of the receiver.
— The GPS IF frequency is 183.6Mhz
— The Bandwidth of the GPS IF filter is
40Mhz
T720 IC description:
1. 1.Qualcomm IC’s:
— MSM5100
— PM1000
— RFR3300
— IFR3000
— RFT3100
— PA2001- 4C/5C
2. Non Qualcomm IC’s:
— Memory IC’s :Flash part 32M bit intel
sawtooth, Eeprom 8M bit intel Jaguar,
SRAM: 8M bit
— Semtech SC801 charger controller
— Harness ASIC
— Phase lock loop
— Reference Oscillator 19.2Mhz
Testing and Troubleshooting GPS:
1. Do the DC analysis of the Front end of the GPS
receiver.
2. The GPS Circuit is turned on momentarily when
you dial 911.
3. Do the visual check of the Antenna coupler circuit
and discrete parts at the Front end of the
receiver.
For all other Testing and Troubleshooting refer to
AGPS testing documentation.
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