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CCS Technical Documentation
RH-3 Series Transceivers
Troubleshooting -- GPS
Issue 1 06/2003 Confidential Nokia Corporation
RH-3
Troubleshooting -- GPS CCS Technical Documentation
Page 2 Nokia Corporation Confidential Issue 1 06/2003
RH-3
CCS Technical Documentation Troubleshooting -- GPS
Contents
Page No
Troubleshooting - Global Positioning System (GPS) Engine........................................ 5
Acronyms and Abbreviations......................................................................................... 6
Troubleshooting the GPS BB ......................................................................................7
Troubleshooting Flowchart ....................................................................................... 7
Flowchart Notes ...................................................................................................... 10
Troubleshooting the GPS RF .....................................................................................13
Limitations .............................................................................................................. 13
GPS Receiver .............................................................................................................13
General Instructions ................................................................................................ 13
Test Equipment ..........................................................................................................14
Path of the Received Signal .......................................................................................14
GPS RF Quick Fault-finding Chart ...........................................................................15
GPS RF Circuitry and Component Placement ...........................................................16
GPS Module Test Points ............................................................................................17
GPS RF General Checking ........................................................................................18
GPS Reference Clock Checking ................................................................................21
GPS RF and GPS BB Interface Checking .................................................................23
GPS RX Chain Checking ...........................................................................................24
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Troubleshooting -- GPS CCS Technical Documentation
Page 4 Nokia Corporation Confidential Issue 1 06/2003
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CCS Technical Documentation Troubleshooting -- GPS
Troubleshooting - Global Positioning System (GPS) Engine
The RH-3 Model 2285 handset supports 800 CDMA / 1900 CDMA + GPS with IS 2000
capability. The RH-3P Model 2270 supports PCS and GPS functionality for Enhanced 911
(E911) services.
GPS circuitry utilizes RF signals from satellites stationed in geosynchronous orbit to
determine latitude and longitude of the handset. The GPS circuitry and the cellular
engine (CE) circuitry are completely separate in the handset. The GPS circuitry is located
exclusively on the secondary side of the PWB.
See Figure 1 for the General Block Diagram.
Figure 1: GPS Block Diagram
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Troubleshooting -- GPS CCS Technical Documentation
Acronyms and Abbreviations
AGPS Assisted GPS
AMPS Advanced Mobile Phone Service
ASIC Application Specific Integrated Circuit
E911 Enhanced 911
FCC Federal Communications Commission
BPSK Binary Phase Shift Keying
BT BlueTooth
C/A Coarse Acquisition-Code
CE Concurrent Engineering
CDMA Code Division Multiple Access
C/No Carrier to Noise ratio [dB-Hz]
DCT Digital Core Technology
DSSS Direct Sequence Spread Spectrum
FCC Federal Communications Commission
GPS Navstar Global Positioning System
HW Hardware
IC Integrated Circuit
L1 Link 1
LPRF Low Power RF
NF Noise Figure
PCS Personal Communications Service
PRN Pseudo Random Noise
PSAP Public Safety Answering Point
PWB Printed Wiring Board
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CCS Technical Documentation Troubleshooting -- GPS
RF Radio Frequency
RHCP Right Hand Circular Polarized
SA Selective Availability
SPS Standard Positioning Service
UTC Universal Time Coordinated
WB Wideband
Troubleshooting the GPS BB
Figure 2: GPS RF-BB ASIC Interface
To troubleshoot the GPS BB, put the GPS engine (GE) and cellular engine (CE) in the
proper mode by selecting the GPS Testing drop-down menu item from the "Troubleshoot-
ing" dialog box. Ensure that the necessary inputs from the CE are good (e.g., power, clock,
and so on). Next, ensure that these inputs produce the proper outputs. Due to the large
level of integration (most functionality is contained in the two ASIC chips), the diagnos-
tics that may be performed are limited.
Visually inspect the GPS circuitry to determine if the problem is physical (dislodged parts,
corrosion, poor solder joints, and so on) prior to performing any diagnostics.
Troubleshooting Flowchart
Before implementing the flowchart, turn the GPS section ON in the "GPS Receiver Con-
trol (AMS)" tab of the GPS component in Phoenix.
Reference Table 1 for GPS Test Points assignment and Figure 10 for GPS Test
Points locations.
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Troubleshooting -- GPS CCS Technical Documentation
Troubleshoot CE
Vcore at 1.5V?
power supply
Yes
No
VIO at 1.8V?
(@ C018)
Yes
GPS_RF_CLK
Troubleshoot CE
(19.2MHz) OK? No
VCTCXO circuit
(J062)
Yes
GPS_EN_RESET is BB ASIC being held in
held high? No reset, troubleshoot
(J061) source in CE
Yes
GPS_SLEEPCLK
Troubleshoot CE
(32.768KHz) OK? No
sleep clock circuit
(J063)
Yes
VRF_GPS regulator Replace regulator
VRF_GPS OK? No No
enable line low? N052
Yes
Yes
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CCS Technical Documentation Troubleshooting -- GPS
GPS_CLK
Replace TCXO or
(16.368MHz) OK? No
GPS RF ASIC
(J010)
Yes
Replace GPS BB
Test Mode 1 OK? No
ASIC
Yes
Determine why CE not
CE sending code
No sending download
download signals?
signals
Yes
Replace GPS BB
SPI interface active? No
ASIC
Yes
Replace GPS RF
RF data and clock? No
ASIC
Yes
Debug RF front end
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Troubleshooting -- GPS CCS Technical Documentation
Flowchart Notes
Clocks and Power
The proper GPS_RF_CLK is a 19.2 MHz, approximately 800mV peak-to-peak sine wave
(see Figure 3).
Figure 3: 19.2MHz System Clock
The GPS_CLK should be a 16.3MHz, 1.8V peak-to-peak square wave (see Figure 4).
Figure 4: GPS_CLK
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CCS Technical Documentation Troubleshooting -- GPS
Test Mode 1
Test Mode 1 is a built-in self-test (BIST) for the GPS BB ASIC that checks for internal
faults. To implement Test Mode 1, select the test mode 1 radio button and then click the
Execute button in the "Rx simple actions" tab of the GPS component in Phoenix.
Code Download
The code store inside the GPS BB ASIC is volatile. As a result, each time power is applied
to the ASIC, the code that runs there must be re-downloaded from the CE. If this process
does not complete correctly, the GE will not work. The interface protocol utilized for this
process is the Universal Synch/Asynch Receiver Transmitter (USART), and the pins on the
GPS BB ASIC are labeled U1Tx, U1Rx, U1_DATA_RDY, and U1_CLK. To determine if this
interface is active, check for activity on these lines at power up. Each of these lines
should have a short burst of activity immediately after power is applied. To capture these
signals, you will need to set the storage scope to single sweep or triggered mode (see
Figure 5).
Figure 5: GPS Code Download U1 CLK U1 RX
SPI Interface
The SPI interface is a three-line synchronous serial interface used by the GPS BB to com-
municate to the GPS RF. These lines are called SPI_CLK, SPI_DATA, and SPI_EN. Activity
should be seen for a short period on these signals each time a mode switch is made (e.g.,
between idle and off mode in the "Rx simple actions" tab of the GPS component in Phoe-
nix). See Figure 6.
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Troubleshooting -- GPS CCS Technical Documentation
Figure 6: Spi Data and Clock
RF Data and Clock
The GPS RF ASIC sends encoded raw GPS data to the GPS BB ASIC for further processing
via a four-line synchronous parallel interface. These signals are data (labeled B0, B1, B2,
and B3) and GPS_CLK. The GPS_CLK has been previously tested (see the flowchart). The
four-data lines should show continuous activity almost immediately after power has
been applied to the phone (see Figure 7).
Figure 7: RF Data and Clock
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CCS Technical Documentation Troubleshooting -- GPS
Troubleshooting the GPS RF
The purpose of this section is to define GPS test limits on the product line and to guide
the GPS RF troubleshooting.
Limitations
Measurements should be done using High-Frequency Probe with spectrum analyzer in
order to measure local and reference frequencies and RF-power levels in intermediate
stages of chain. Oscilloscope is used to measure DC-voltages and low frequency signals.
Digital multimeter is also useful measurement equipment in faultfinding. Also cellular
tester is needed in order to perform tests mentioned in this section.
External RF connector is implemented for improving reliability of the measurements and
should be used when reasonable.
GPS RF-section is mainly build around of TRF5101 PG2.1 IC (N054) ASIC. The GPS RF
block has a separate front end filter, inter stage filter, LNA, TCXO, and down converter
circuitry.
In this RF troubleshooting section, tolerances are specified for critical GPS RF signals and
voltages.
Before changing a single ASIC or component, please check the following items:
1 The soldering and alignment marks of the GPS ASICs
2 Supply voltages and control signals are OK
NOTE 1: The RF ASIC module is static discharge sensitive! It is recommended that EDS-protected
clothes and shoes are worn and that grounded soldering irons are used.
NOTE 2:The shield lid must be always replaced with new one after it is opened. Check that there are
no short circuits on PWB caused by plate ends.
GPS Receiver
General Instructions
Receiver troubleshooting is divided into four sections:
1 GPS RF general checking
2 GPS reference clock checking
3 GPS RF and GPS BB interface checking
4 GPS RX chain checking
The fastest way to troubleshoot GPS RF is to follow the GPS RF Fault-finding chart Quick
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Troubleshooting -- GPS CCS Technical Documentation
Reference (See Figure 9).
Please note that before changing ASICs or filters, soldering and missing components
must be checked visually. There are no parameters in GPS RF, which should be tuned
externally. Accurate signal levels are not shown in the flowcharts below because of the
figures apply with specific measurement probes. It is useful to compare the results
against reference phones.
Test Equipment
1 Signal generator up to 2 GHz
2 Oscilloscope with 10:1 passive probe
3 High Frequency Probe for Spectrum Analyzer (Please note that the signal levels
mentioned in the RX troubleshooting have been measured with an active probe.)
4 Spectrum analyzer up to 6.7 GHz
5 PC with Phoenix SW and GPS option
Path of the Received Signal
1575.42 MHz
4.092MHz AGC
Image Reject
LNA Mixer
4 Bit
ADC
4
ADCout
BPF SAW LO=1571.328 MHz