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Customer Care Solutions Technical Documentation
6(b) - RF Troubleshooting and Manual Tuning Guide
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NHL-10 CCS Technical Documentation RF Troubleshooting
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Table of Contents Page No Introduction ................................................................................................................... 5 General troubleshooting ................................................................................................ 6 RF Key Component Placement ..................................................................................... 7 Receiver Troubleshooting ............................................................................................. 9 General Description .................................................................................................... 9 General Instructions for RX Troubleshooting .......................................................... 10 Measuring RX I/Q signals using RSSI ................................................................... 10 Measuring RX performance using SNR measurement ........................................... 11 Measuring the RX module manually using Oscilloscope and Spectrum Analyzer 12 GSM900 .................................................................................................................. 12 GSM1800 ................................................................................................................ 14 GSM1900 ................................................................................................................ 15 Measurement points in the Receiver ...................................................................... 17 Tuning of the RX Using Phoenix ................................................................................ 19 RX Channel Select Filter Calibration ....................................................................... 19 RX Calibration .......................................................................................................... 19 RX Band Filter Response Compensation .................................................................. 22 Transmitter Troubleshooting ....................................................................................... 25 General Description .................................................................................................. 25 Preparation for Fault Finding .................................................................................... 26 Fault-finding chart: TX-BB interface and control signals ...................................... 28 Fault-finding chart: RF side of transmitter ............................................................. 29 Transmitter Tuning ...................................................................................................... 30 Introduction ............................................................................................................... 30 TX IQ Tuning ............................................................................................................ 30 TX Power Level Tuning ........................................................................................... 34
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NHL-10 RF Troubleshooting CCS Technical Documentation
Introduction
This document describes the troubleshooting and RF tuning of Nokia 6600 (NHL-10). In general, two types of measurements have to be performed during the troubleshooting and repair of phones:
·
RF measurements shall be done with a spectrum analyzer, either connected directly to the RF connector of the board ("antenna point"), or used together with a high-frequency probe to measure RF signals at points along the TX or RX chain.
· LF (Low-Frequency) and DC measurements shall be done either with a multimeter, or with an oscilloscope together with a 10:1 probe.
All tuning must be done with Phoenix Service Software, version A9 2003.15.2.25, or later. Always make sure that the measurement set-up has been calibrated when measuring RF parameters at the RF connector. Remember to include the correct losses in the module repair jig and the connecting cable when realigning the phone. Most RF semiconductors are static discharge sensitive. ESD protection must be taken into account during repair (ground straps and ESD soldering irons). Mjølner RF ASIC is moisture sensitive. Therefore, Mjølner RF ASIC must be pre-baked prior to soldering. RF calibration done via Phoenix software is temperature sensitive because of calibration of 26MHz reference oscillator (VCXO). According to the Mjølner specification, ambient temperature has to be in the range of 22 to 36oC.
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NHL-10 CCS Technical Documentation RF Troubleshooting
General troubleshooting
The first step of fault-finding should always be a visual inspection. Carefully inspect the RF area using a microscope and look for cracks, solder bridges, dry joints, missing components, components that have partially come off and other anomalies. Capacitors can be checked to see that they are not short-circuited, and inductors that they are not open circuits. Also check that power supply lines are not short-circuited, i.e. not 0 to ground.
Instruments needed for trouble-shooting (minimum requirement):
· · ·
Oscilloscope Multimeter Spectrum analyzer (SA)
Note: Use an attenuator at the spectrum analyzer input to ensure that the SA will not become damaged by excessive input power from the phone. Check the spectrum analyzer for maximum allowable input power.
· · ·
Power supply that can deliver at least 2Adc Nokia 6600 module jig (also called test jig) PC with Phoenix installed
Note: In this text the following terms are used interchangeably: GSM900 = EGSM900 = EGSM GSM1800 = DCS band GSM1900 = PCS band
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RF Key Component Placement
The following figure shows the key components of the RF section.
Figure 1: RF Key Components
shows key components of the RF section.
E-GSM900
GSM1800
Figure 2: RF Key Components
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NHL-10 CCS Technical Documentation RF Troubleshooting
Figure 3: RF Key Components
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Receiver Troubleshooting
General Description
Figure 4: Receiver Signal Path
The receiver is a direct conversion, triple-band linear receiver. NHL-10 uses Mjølner RFIC with external VCO. The received RF signal from the antenna/RF connector goes into the RF antenna switch where the signal is fed to the E-GSM900, GSM1800 or GSM1900 path. For each band, a RX bandpass SAW filter with unbalanced input and balanced output follows. All blocks are specified as 50 single ended, only the SAW filter output to the Mjølner input is differentially matched to LNA Gopt. The LNAs are integrated in Mjølner and have two gain levels. The first one is max. gain nominally 12 dB, the second one is about 30 dB below max. gain. The gain selection control of the LNAs is done via the serial interface. The differential RX signals are further amplified in the "pre-gain" stage and then mixed down to baseband inside Mjølner using two Mixers with a 90° phase shift in the LO signal resulting in an in- and quadrature phase paths. Local oscillator signal is generated with the external VCO. The VCO signal is buffered and divided by 2 (DCS/PCS) or by 4 (EGSM). Accurate phasing is generated in LO dividers. The Rx BB chain incorporates AGC, channel select filter and DC compensation. The AGC is adjusted in 6 dB steps in Mjølner. The DCN1 gain can be adjusted to +24/+18/+12/+6/0 dB. The attenuator gain can step from 0/-6/-12/-18/-24/-30/-36/-42/-48dB. Other BB amplifiers have a nominal summed gain of 58dB. The total dynamic range of AGC alone is 72dB. The 3rd order active channel filters in Mjølner defines the channel selectivity (flat response up to +/-90kHz typical). Integrated base band filters are based on active RC filters with on-chip capacitors. The baseband filters are distributed to following stages: BBAMP1, LPF1, LPF2. DC compensation is split to DCN1 and DCN2. DCN1 is used to compensate DC offset from RF front-end imper-
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NHL-10 CCS Technical Documentation RF Troubleshooting
fections. DCN2 centres the differential signal with respect to the common mode reference voltage of 1.35V. Differential, filtered I/Q-signals are finally fed to the sigma-delta ADC's in the UEM. Further filtering in the digital domain occurs in the sinc decimation filter and DSP based FIR filters
General Instructions for RX Troubleshooting
Connect the phone to a PC with DAU-9S cable and dongle and follow the following instructions.
Measuring RX I/Q signals using RSSI · Start Phoenix Service Software and establish a connection to the phone. · · · · · · · · Select File -> Scan Product Ctrl R. Wait until the phone software version is shown in the lower part of the screen. Select Testing -> RF controls. Select Band -> GSM900/GSM1800/GSM1900. Active unit -> RX. Operation mode -> Burst. RX/TX channel -> 37/700/661. Select RF Alt-M Testing -> T RSSI -> R
The set-up now looks like this:
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·
Apply a signal with frequency of: EGSM: 942.467MHz (channel 37 + 67.710KHz offset), GSM1800: 1842.867MHz (channel 700 + 67.710KHz offset), GSM1900: 1960.067MHz (channel 661 + 67.710KHz offset), and a power level of 80dBm to the RF connector (remember to compensate for the cable loss). In RSSI reading click Read now.
·
The resulting RSSI level should be 80dBm in each band.
Measuring RX performance using SNR measurement
Note: This measurement also provides an indication of the conducted sensitivity.
· · · · ·
Start Phoenix Service Software and establish a connection to the phone. Select File -> Scan Product Ctrl R. Wait until the phone software version is shown in the lower part of the screen. Select Testing -> RF controls. Select Band -> GSM900/GSM1800/GSM1900.
· Active unit -> RX. · Operation mode -> Burst. · · RX/TX channel -> 37/700/661. Select Maintenance Alt-M Testing -> T SNR Measurement -> M
· · · · · ·
Select Fast SNR. Choose the respective band (EGSM900, GSM1800, GSM1900). Press Measure. Follow the instructions for Signal generator setup in the popup window. Press OK. Read the SNR result. The SNR should be: EGSM900: > 20dB GSM1800: > 18dB GSM1900: > 18dB Check the sensitivity value.
·
The set-up should now look as shown in the following figure. The icon also includes a pop-up window for reference.
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Measuring the RX module manually using Oscilloscope and Spectrum Analyzer
Spectrum Analyzer level values depend on the probe type and should be validated using a known good NHL-10 sample. The levels that are given here are measured using a high frequency probe. Measuring with Oscilloscope on RXINN or RXQINN (J606 608) and RXID or RXQD (J211 J212) is recommended only if RSSI reading does not provide enough information. No dedicated test points exist for RX I/Q signals, however, they can be accessed by probing on a via hole plating.
GSM900 · Start Phoenix Service Software and establish a connection to the phone. · · · · Select File -> Scan Product Ctrl R. Wait until the phone software version is shown in the lower part of the screen. Select Testing -> RF controls. Select Band -> GSM900.
· Active unit -> RX. · Operation mode -> Continuous. · · RX/TX channel -> 7. AGC -> 9.
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The input freq/level of the signal generator is 942.467710MHz, -60dBm.
Figure 5: Fault finding chart for GSM900
Apply -60 dBm 942.4 MHz, offset 67.71 kHz from generator to antenna connector
YES EGSM chain functional
Check RSSI using Phoenix Does it match Sig Gen Output level ? NO
NO Is L.O running ?
Refer to Synthesiser Fault finding chart
YES Probe J606 -609 RX I &Q Does waveform look like example given earlier ? YES YES Replace UPP Probe J211 &J212 Is digital data visable ? visible YES Check RX/TX switch Check RX/TX switch at RX 900 Z601 Input -63 dBm Output -63dbm Oscilloscope check Vc1, Vc2, Vc3 at Z601 signal 0V
NO
NO
NO Check Mjoelner
NO Spectrum analyzer EGSM SAW filter Z604 output -66 dBm YES Spectrum analyzer Check signal after inductors L606 and L607 -66 dBm YES Oscilloscope VRX 2.7 V on Mjoelner NO NO Check SAW filter Z604
YES
Replace UEM
Check inductors L606, L607
NO Check Base band
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NHL-10 CCS Technical Documentation RF Troubleshooting
Probed RX I/Q signals J606 - 609 with signal setting to 942.467710MHz, -60dBm. Note that the display is the same for both GSM1800/1900 bands as well.
· · ·
Signal amplitude: 456mV DC offset: Frequency: 1.36V approx 67KHz
GSM1800 · Start Phoenix Service Software and establish a connection to the phone. · · · · · · · · Select File -> Scan Product Ctrl R. Wait until the phone software version is shown in the lower part of the screen. Select Testing -> RF controls. Select Band -> GSM1800. Active unit -> RX. Operation mode -> Continuous. RX/TX channel -> 700. AGC -> 9.
The input freq/level of the signal generator is 1842.867710MHz, -60dBm.
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Figure 6: Fault finding chart for GSM1800
Apply -60 dBm 1842.8 MHz, offset 67.71 kHz from generator to antenna connector
YES
EGSM chain functional
Check RSSI using Phoenix Does it m atch Sig Gen Output level ?
NO
NO
Is L.O running ?
Refer to Synthesiser Fault finding chart
YES Probe J606 -609 RX I &Q Does waveform look like exam ple given earlier ?
Check RX/TX switch at RX 1800 Z601 Input -63 dBm Output -65dBm Oscilloscope check Vc1, Vc2, Vc3 at Z601 signal 0V
NO
NO
NO Check Mjoelner
YES YES
Replace UPP Probe J211 &J212 Is digital data visible visable ? YES Check RX/TX switch
NO
Spectrum analyzer EGSM SAW filter Z602 output -70 dBm
NO
Check SAW filter Z602
YES
Replace UEM
YES
Spectrum analyzer Check signal after inductors L603 and L604 -73 dBm
NO
Check inductors L603, L604
YES
Oscilloscope VRX 2.7 V on Mjoelner
NO
Check Base band
GSM1900 · Start Phoenix Service Software and establish a connection to the phone. · · · · · · · · Select File -> Scan Product Ctrl R. Wait until the phone software version is shown in the lower part of the screen. Select Testing -> RF controls. Select Band -> GSM1900. Active unit -> RX. Operation mode -> Continuous. RX/TX channel -> 661. AGC -> 9.
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NHL-10 CCS Technical Documentation RF Troubleshooting
The input freq/level of signal generator is 1960.067710MHz, -60dBm
Figure 7: Fault finding chart for GSM1900
Apply -60 dBm 1960 MHz, offset 67.71 kHz from generator to antenna connector
YES EGSM chain functional
Check RSSI using Phoenix Does it match Sig Gen Output level ? NO
NO Is L.O running ?
Refer to Synthesiser Fault finding chart
YES Probe J606 -609 RX I &Q Does waveform look like example given earlier ? YES YES Replace UPP Probe J211 &J212 Is digital data visable ? visible YES Check RX/TX switch Check RX/TX switch at RX 1900 Z601 Input -63 dBm Output -65 dBm Oscilloscope check Vc1, Vc2, Vc3 at Z601 signal Vc1, Vc3 =0V Vc2=2.7V
NO
NO
NO Check Mjoelner
NO Spectrum analyzer EGSM SAW filter Z603 output -70 dBm YES Spectrum analyzer Check signal after inductors L608 and L609 -73 dBm YES Oscilloscope VRX 2.7 V on Mjoelner NO NO Check SAW filter Z603
YES
Replace UEM
Check inductors L608, L609
NO Check Base band
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NHL-10 RF Troubleshooting Measurement points in the Receiver
Figure 8: Measurement points at the RX SAW filters Z602, Z603, Z604
CCS Technical Documentation
Figure 9: Measurement points for I/Q baseband signals
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Figure 10: Measurement points for RX I/Q digital signals
Figure 11: Measurement points at the Antenna switch
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Tuning of the RX Using Phoenix
RX Channel Select Filter Calibration
This calibration is calibrating the Baseband filter inside Mjølner ASIC. It is done by internally measuring a prototype filter, for this reason the calibration is done once, not separately for all three bands.
·
Select Tuning -> RX Channel Select Filter Calibration.
·
Press Tune.
RX channel select filter calibration is finished.
RX Calibration
The RX Calibration is used to determine the gain at different gain settings for the front-end and the Mjølner ASIC and needs to be done in all three bands. RX-calibration requires an external signal generator.
· ·
Select Tuning -> RX calibration. Select band: GSM900.
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NHL-10 CCS Technical Documentation RF Troubleshooting
·
Press Start.
· ·
Follow the instructions in the popup window. Press OK.
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·
Press Save & Continue.
·
Press OK and continue.
For GSM1900 just repeat the same procedure as for GSM900/GSM1800. If the calibration is OK, you should see "RX calibration was completed successfully" on the display.
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NHL-10 CCS Technical Documentation RF Troubleshooting
RX Band Filter Response Compensation
The Rx Band Filter Response Compensation has nine steps for each band. The RF Band Filter Response Compensation requires an external signal generator.
·
Select Tuning -> RX Band Filter Response Compensation.
·
Select Manual.
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· ·
Follow the instructions given in the following pop-up window. There are nine steps in all. After completing the nine steps of calibration at nine frequencies, press Save & Continue.
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Repeat all steps as for GSM900 for the GSM1800 band. Follow all the instructions in the popup window. Repeat the procedure for GSM1900. The tuning is completed.
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Transmitter Troubleshooting
General Description
A simple block diagram of the TX part of the phone is shown in the following figure. The voice or data signals to be transmitted come from the UEME IC in the BB (Base Band) area, and go to the Mjølner IC, where they are up-converted to RF. The TX signals going from UEME to Mjølner are called the IQ signals, and consist of two balanced signals { TXIN, TXIP } and { TXQN, TXQP }, i.e. a total of four signal lines. In addition to the IQ-signals, there are also control signals going between BB and RF.
Figure 1: TX RF Block Diagram
BB-RF Interface Signals:
Mjølner
From UEME:
TXIQ TXC
V_BAT
PA Coupler Ant-Switch
1800 / 1900MHz
4
4
From UPP:
TXP RFBUSCLK RFBUSEN1 RFBUSDA RESET
1/2
4
VTXB_900 (BUFFER BIAS)
900MHz SAW Discrete TX buffer/amp
Power Loop Filter
DET VBD (DIODE BIAS)
1/4
VPD_900 VPD_1800 2
Power Detect
2
LO (LO=Local Oscillator)
Synthesizer
The picture below shows the two shielding cans where the TX circuitry is located (the lid has been removed). The shielding can on the right side contains BB-RF interface circuitry, the Mjølner RF system IC, a SAW filter for the EGSM band, and a balun for the DCS/PCS band. The shielding can on the left side contains the power amplifier (PA), the EGSM pre-amplifier, the directional coupler, the power detector, and the Antenna Switch Module (ASM).
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NHL-10 CCS Technical Documentation RF Troubleshooting
Figure 2: GSM RF area
Directional Coupler
Power Detector Circuit
ASM Power Amplifier
Mjolner
Up-mixer bias networks (EGSM/DCS/PCS) DCS/PCS Balun
EGSM Pre-Amp
EGSM SAW Filter
Preparation for Fault Finding
1 2 3 4 Place phone (mechanics removed) on module jig. Connect the module jig to the PC via a DAU-9S cable. Connect the module jig to the power supply (4.2V). Connect the RF output to a spectrum analyzer or another measurement instrument. Use a 10dB attenuator at the input to spectrum analyzer to avoid damaging it. Make sure the dongle is connected and start Phoenix. In Phoenix, select File -> Open Product -> NHL-10 6600 Product Menu. Select Testing -> RF Controls. From the toolbar, set Operating Mode to Local. Select band: GSM900, GSM1800 or GSM1900.
5 6 7 8 9
10 Set Operation Mode to Burst. 11 Set Active Unit to TX. 12 Set TX Data Type to All1.
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13 Set RX/TX Channel to 37 for GSM900, 700 for GSM1800 or 661 for GSM1900. 14 Set TX PA Mode to Free. 15 Set TX Power Level to 5 in GSM900, otherwise to 0.
Phoenix should now look as shown in the following figure.
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NHL-10 CCS Technical Documentation Fault-finding chart: TX-BB interface and control signals
Figure 3: Fault finding chart of BB-TX interface & some control signals
Start Cont3 Cont2 Cont1
RF Troubleshooting
VR3
Using a multimeter, check power supply lines to Mjolner: Line VR1a VR2 VR3 VR5 VR6 VR7
Voltage Test Points
4.75V 2.78V 2.78V 2.78V 2.78V 2.78V OK
J612 J613 J614 (J601) J616 J617 J618
Not OK
Check UEME (D190) in BB area
VR6
VR5
Using the oscilloscope, check TXC and TX IQ lines from UEME to Mjolner: Line TXIOUTP TXIOUTN TXQOUTP TXQOUTN TXC
Testpoint DC Voltage AC Voltage Frequency
R715 R715 R716 R716 J611
1.1Vdc 0.4Vp-p 1.1Vdc 0.4Vp-p 1.1Vdc 0.4Vp-p 1.1Vdc 0.4Vp-p Depends on the power level OK
67kHz 67kHz 67kHz 67kHz 217Hz
Not OK
Check UEME (D190) in BB area
Mjolner output bias network
VR1A
VR2 Not OK Check UPP (D100) in BB area TXIOUTP TXIOUTN TXC
TXP
Using the oscilloscope, check TXP from UPP: Line TXP
Testpoint Vpp Frequency
J610
1.8V
217Hz
TXQOUTP TXQOUTN
OK Using the oscilloscope, check control signals from Mjolner to ASM1: Line Cont1 Cont2 Cont3
1
VR7 Check serial interface between Mjolner & UPP
Testpoint
GSM900
GSM1800
GSM1900
Period
R702 R703 R701
0V 0V 2.7V
2.7V 2.7V 0V
2.7V 2.7V 0V
4.615ms 4.615ms 4.615ms
Not OK
ASM = Antenna Switch Module OK Use Phoenix to set TX_Data_Type to 'Random' and to set TX Power Level to '5'
Use the oscilloscope to check the voltage supply line to Not OK the transistorized pre-amplifier: VTXB_900
Check serial interface between Mjolner & UPP
Figure 4: Oscilloscope screen shots
Typical oscilloscope plots of the four TXIQ-lines: zoom 0.5Vpp VTXB_900
4.615ms 2.7V 1.1Vdc ~67kHz waveform for all 1's
Ctrl signals to ASM: ( DCS/PCS ) TXC-signal TXP-signal Cont1 2.7V 4.615ms
6
4.615ms
4.
EGSM900 channel = 37 PL = 5
Cont2
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NHL-10 RF Troubleshooting Fault-finding chart: RF side of transmitter
In Phoenix select: Active unit=TX, Operation Mode=Burst, TxPA Mode=Free, TxData Type=Random, and for each band: GSM900, channel=37, PL5 GSM1800, channel=700, PL0 GSM1900, channel=661, PL0
CCS Technical Documentation
PA EGSM input
Transmitter is OK OK OK NOK Tune TX power NOK Check power control loop
VPD_900
PA EGSM output
Measure power at RF connector: GSM900: Power between 31 & 35dBm GSM1800 & GSM1900: Power between 28 & 32dBm NOK Signal found? Yes Check power control loop OK Correct signal at ASM output? No Correct signal at ASM input? No Correct signal at directional coupler input? No Correct signal at power amplifier input? No EGSM => check pre-amp & SAW DCS/PCS => check balun OK Check bias network at output of Mjolner IC (Discrete components: R's, L's & C's) OK Check fault finding chart of TX-BB interface OK Mjolner broken? Replace it & retune RF Yes Yes Yes Yes No
OK
Check all power levels
Search for output signal with 500MHz span. Signal found on incorrect frequency?
VPD_1800
Yes
Trouble-shoot synthesizer Check power control loop
PA DCS/PCS input
PA DCS/PCS output
ASM DCS/PCS input
Using the oscilloscope, check power control loop signals (Compare to oscilloscope screen plots shown below) RF connector broken? Line VBD DET VPD_900
Testpoint
VTXB_900 (pre-amp bias)
ASM EGSM input
ASM TX output VBD DET
ASM broken? Yes directional coupler broken?
R801 R802 R818
Balun DCS/PCS output
Note: When using the SA to check if a signal is 'correct' at a certain point (at input/output of ASM, directional coupler, PA, SAWfilter, balun, etc.), the best way to do so is to compare with the signal of a working sample of a phone. The reason for this is that the level seen on the SA screen will vary depending on the type of probe, the impedance of the measurement point, etc.
EGSM SAW output
Check power control loop
OK
power amplifier broken?
VBD: bias to pwr detector
4.615ms 2.7V
Spectrum analyzer screen shots Measurements done at RF connector
DET: output of pwr detector
VPD_900: input voltage ctrl signal to PA
EGSM900 channel = 37 PL = 5
Span = 0Hz Span = 3MHz
GSM900, PL=5
GSM900, PL=5
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Transmitter Tuning
Introduction
In the transmitter, there are two kinds of tunings that can be performed. These are IQ-tuning and power level tuning. In general, different repairs require different tunings. In order to decide which tuning is necessary after a repair, it is important to understand well the functionality of the repaired circuit. In general, it is recommended that if any TX component is changed, both these tunings are done.
Note: All tunings are done in local mode using Phoenix to control the phone.
TX IQ Tuning
The tuning must be carried out in all three bands. In addition to Phoenix, a spectrum analyzer (SA) is needed. Connect the SA to the RF connector of the module jig. The settings of the spectrum analyzer will depend on the band to be tuned. The following table summarizes the settings for each of the three bands.
Table 1: Spectrum Analyzer Settings EGSM900 Center frequency Frequency span Resolution Bandwidth Video Bandwidth Sweep Time Trace Type Detector Type Reference Level Marker 1 Marker 2 Marker 3 897.4MHz 300kHz 3kHz 3kHz 3 sec Clear/Write Max Peak 35dBm 897.33229 MHz 897.4MHz 897.46771MHz GSM1800 1747.8MHz 300kHz 3kHz 3kHz 3 sec Clear/Write Max Peak 35dBm 1747.73229 MHz 1747.8MHz 1747.86771MHz GSM1900 1880MHz 300kHz 3kHz 3kHz 3 sec Clear/Write Max Peak 35dBm 1879.93229 MHz 1880MHz 1880.06771MHz
For this tuning, two windows of Phoenix must be open: (1) Testing -> RF Controls, and (2) Tuning -> TX IQ Tuning, as seen in figures below.
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Figure 1: Phoenix set-up
Figure 2: Phoenix set-up
After opening the two before-mentioned windows, Phoenix should look as shown in the following figure.
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NHL-10 CCS Technical Documentation RF Troubleshooting
Figure 3: Phoenix set-up
The following table summarises the settings of the RF control window for the IQ tuning of the three bands.
Table 2: RF Control Window Settings Band GSM900 GSM1800 GSM1900 TX Data Type All 1 All 1 All 1 5 0 0 TX Power Level 37 700 661 RX/TX Channel
To start the IQ tuning, press Start in the IQ Tuning window.
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The spectrum analyzer screen should now look similar to that of the figure below (GSM900 case).
Figure 4: Spectrum analyzer screen shot when performing IQ tuning
Marker 1 [T1]
RBW VBW SWT
3 kHz 3 kHz 3 s
1 [T1] 2 [T1]
RF Att
Unit
30 dB
dBm
33.35 dBm
Ref Lvl 35 dBm
35
33.35 dBm 897.33229000 MHz 1
27.5 dB Offset
30
A
897.33229000 MHz -6.76 dBm 897.40000000 MHz 3 [T1]
10 20
-10.74 dBm 897.46771000 MHz
0
1MA
2
-10
3
-20
-30
-40
-50
-60 -65
Center 897.4 MHz
Date: 14.JAN.2002 13:11:55
30 kHz/
Span 300 kHz
The purpose of this tuning is to reduce the frequency components at marker 2 (carrier leakage) and marker 3 (+67kHz / upper sideband) as much as possible. Adjust the TXI DC Offset and the TXQ DC Offset buttons in the TX IQ Tuning window so that the carrier level (marker 2) reaches a minimum. After this adjustment, the carrier (marker 2) should be at least 40dB below the lower side band (marker 1). Next, use the Amplitude difference and the Phase difference buttons in the TX IQ Tuning window to adjust the upper side band (marker 3) to a minimum. Now, marker 3 should also be at least 40dB below marker 1. At this point, the spectrum analyzer screen should look similar to that of the figure below.
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NHL-10 CCS Technical Documentation RF Troubleshooting
After reducing the amplitude of the frequency components at marker 2 and 3 to a minimum, press Save & Continue. The EGSM tuning has now been completed. Now, using the spectrum analyzer settings of Table 1, and the RF control settings of Table 2, follow exactly the same procedure to perform IQ tuning in the GSM1800 and GSM1900 bands.
TX Power Level Tuning
This tuning is done separately in all three bands, and requires a spectrum analyzer to measure the burst power of the GSM RF signal. When measuring the RF output (burst) power on a spectrum analyzer, use the settings found in the following table:
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Table 3: Spectrum Analyzer Settings
EGSM900 Center frequency Frequency span Resolution Bandwidth Video Bandwidth Sweep Time Trigger Type Trace Type Detector Type 897.4MHz Zero-span 1MHz 1MHz 1ms Video Clear/Write Max Peak GSM1800 1747.8MHz Zero-span 1MHz 1MHz 1ms Video Clear/Write Max Peak GSM1900 1880MHz Zero-span 1MHz 1MHz 1ms Video Clear/Write Max Peak
In Phoenix, select Tuning -> TX Power Level Tuning.
Figure 5: Phoenix menu select
Phoenix should now as shown in the figure below.
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NHL-10 CCS Technical Documentation RF Troubleshooting
Figure 6: Phoenix power level tuning menu
Connect the module jig RF output to the measurement instrument. In the EGSM band the power must be tuned in both high and low TX PA mode. In the two upper bands (GSM1800 and GSM1900) there is only one mode. For each band, tune the power by adjusting the coefficient in the Tx Power Level Tuning window in Phoenix until the target level is reached (measured on the spectrum analyzer). Remember to take into account the external power loss, i.e. the loss of the cable and the external attenuator at the spectrum analyzer input. The coefficient must be tuned for the base level and other levels, marked with bold letters in Phoenix (GSM900: PL19/15/7/5, GSM1800/1900: PL15, 11, 0). When the tuning has been completed, press Save & Continue to save the new tuning values into the phone memory. The following figure shows the power level tuning at the GSM900 band.
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Figure 7: Phoenix screen shot
The next figure shows the spectrum analyzer screen shot associated with the above Phoenix screen shot.
Figure 8: Spectrum analyzer screen short during power level tuning
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