Nokia NPD-4 Series Guide

CCS Technical Documentation
NPD-4 Series Transceivers
Issue 1 02/2003 Confidential Nokia Corporation
Troubleshooting — GPS

NPD-4
Troubleshooting — GPS CCS Technical Documentation
Page 2 Nokia Corporation Confidential Issue 1 02/2003

CCS Technical Documentation Troubleshooting — GPS
NPD-4
Issue 1 02/2003 Nokia Corporation Confidential Page 3
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 RF General Checking ........................................................................................18
GPS Reference Clock Checking ................................................................................21
GPS RF and GPS BB Interface Checking .................................................................23
GPS RX Chain Checking ...........................................................................................24

NPD-4
Troubleshooting — GPS CCS Technical Documentation
Page 4 Nokia Corporation Confidential Issue 1 02/2003

CCS Technical Documentation Troubleshooting — GPS
NPD-4
Issue 1 02/2003 Nokia Corporation Confidential Page 5
Troubleshooting - Global Positioning System (GPS) Engine
The NPD-4 handset supports 800 Amps and 800 CDMA / 1900 CDMA + GPS with IS 2000
capability. The NPD-4 engine supports CDMA 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
almost exclusively on the secondary side of the PWB, underneath the display module.
See Figure 1 for the General Block Diagram.
Figure 1: GPS Block Diagram
GPS Engine
BB
ASIC Baseband
Core
1.8V GPS BB/Cellular I/F
SPI
Interface
GPS Data RF-BB
I/F
(1.8V)
4
RF
Control
I/F
(1.8V)
RF
Ctrl I/F
ARM
RAM
RTC CAL
TCXO CAL
GPS Clk
RF
ASIC
Oscillator
AGC
A/D
PLL RF Ctrl
I/F
LNA
Vbatt
Gnd
Vbatt
Gnd
TCXO
16.364Mhz
VLNA (2.8V)
VRF (2.8V)
Cellular Engine
UEM
UPP
Cellular
RF SLEEP CLK
System Clock
Vcore
REG
32768Hz
crystal
SLEEPX
USART
32KHz RTC
System Clock
19.2MHz (CDMA)
4
SleepX
Resetx
Timestamp
Secondary UART
(Diagnostic)
Vcore
VIO
2nd regulator for
VLNA is optional
(Not Populated)

NPD-4
Troubleshooting — GPS CCS Technical Documentation
Page 6 Nokia Corporation Confidential Issue 1 02/2003
Acronyms and Abbreviations
AGPS Assisted GPS
AMPS Advanced Mobile Phone Service
ASIC Application Specific Integrated Circuit
E911 Enhanced 911
FCC Federal Communications Commission
CDMA Code Division Multiple Access
C/No Carrier to Noise ratio [dB-Hz]
GPS Navstar Global Positioning System
HW Hardware
IC Integrated Circuit
LPRF Low Power RF
NF Noise Figure
PWB Printed Wiring Board
RF Radio Frequency

CCS Technical Documentation Troubleshooting — GPS
NPD-4
Issue 1 02/2003 Nokia Corporation Confidential Page 7
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, ensure that the CE is not in power-saving mode. This
will allow the GE to run. Turn the GPS section ON in the “GPS Receiver Control (AMS)”
tab of the GPS component in Phoenix.
Reference Table 1 for GPS Test Points assignment and Figure 10 for GPS Test
Points locations.
1.8V from
Cellular Engine

NPD-4
Troubleshooting — GPS CCS Technical Documentation
Page 8 Nokia Corporation Confidential Issue 1 02/2003
Troubleshoot CE
power supply
Vcore at 1.5V?
at CO57
(See Figure 10)
VIO at 1.8V?
(@ C018)
at open pad
(See Figure 10)
GPS_RF_CLK
(19.2MHz) OK?
(J062)
Troubleshoot CE
VCTCXO circuit
GPS_EN_RESET is
held high?
(J061)
BB ASIC being held in
reset, troubleshoot
source in CE
GPS_SLEEPCLK
(32.768KHz) OK?
(J063)
Troubleshoot CE
sleep clock circuit
VRF_GPS OK? VRF_GPS regulator
enable line low? Replace regulator N052
Yes No
Yes
No
Yes
No
Yes
Yes
No
No No
Yes Yes

CCS Technical Documentation Troubleshooting — GPS
NPD-4
Issue 1 02/2003 Nokia Corporation Confidential Page 9
GPS Self Test OK?
(use GPS Quick Test
function in Phoenix)
Replace GPS BB
ASIC
CE sending code
download signals?
Determine why CE not
sending download
signals
SPI interface active? Replace GPS BB
ASIC
RF data and clock? Replace GPS RF
ASIC
Debug RF front end
Yes
No
Yes
No
Yes
No
Yes
No
Yes
GPS_CLK
(16.368MHz) OK?
(J010)
Replace TCXO or
GPS RF ASIC
No

NPD-4
Troubleshooting — GPS CCS Technical Documentation
Page 10 Nokia Corporation Confidential Issue 1 02/2003
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