GSM Measurement Guide
Agilent Technologies E4406A VSA Series
Transmitter Tester
Manufacturing Part Number: E4406-90101
Printed in USA
April 2000
© Copyright 1999-2000 Agilent Technologies, Inc.
The information contained in this document is subject to change without notice.
Agilent Technologiesmakesnowarrantyofanykindwithregard to this
material, including but not limited to, the implied warranties of
merchantability and fitness for a particular purpose. Agilent
Technologies shall not be liable for errors contained herein or for
incidental or consequential damages in connection with the furnishing,
performance, or use of this material.
2
Contents
1. Understanding GSM
What Is GSM?. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6
Mobile Stations and Base Transceiver Stations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Uplink and Downlink . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
What Is an ARFCN? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
What are Timeslots? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
What Does the E4406A VSA Series Transmitter Tester Do? . . . . . . . . . . . . . . . . . . . . . . . . . . 9
Other Sources of Measurement Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
Instrument Updates at www.agilent.com/find/vsa . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
2. Setting Up the GSM Mode
GSM Mode . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
How to Make a Measurement. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12
Changing the Mode Setup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 13
Changing the Frequency Channel . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18
GSM Measurement Key Flow . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20
Installing Optional
Measurement Personalities. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .32
Available Options . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
License Key Numbers. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .33
Installing a License Key Number. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34
Using the Uninstall Key. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .35
3. Making GSM Measurements
GSM Measurements. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38
Preparing for Measurements. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
Initial Setup. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39
Measure Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40
Measurement Setup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .41
Making the Transmit Power Measurement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
Purpose . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
Measurement Method. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 44
Making the Measurement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 45
Results. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46
Changing the Measurement Setup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47
Troubleshooting Hints . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .48
Making the Power vs. Time Measurement. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
Purpose . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
Measurement Method. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 49
Making the Measurement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 50
Results. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 51
Changing the Measurement Setup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 52
Changing the View . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 53
Changing the Display . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .53
Troubleshooting Hints . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .53
Making the Phase and Frequency Error Measurement. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54
Purpose . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54
Measurement Method. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 54
3
Contents
Making the Measurement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .55
Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .56
Changing the Measurement Setup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .59
Changing the View. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .59
Changing the Display. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .60
Troubleshooting Hints . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .60
Making the Output RF Spectrum Measurement. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .61
Purpose . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .61
Measurement Method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .61
Making the Measurement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .65
Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .66
Changing the Measurement Setup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .67
Changing the View. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .71
Troubleshooting Hints . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .71
Making the Spectrum (Frequency Domain) Measurement. . . . . . . . . . . . . . . . . . . . . . . . . . . .72
Purpose . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .72
Measurement Method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .72
Making the Measurement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .72
Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .73
Changing the Measurement Setup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .74
Changing the View . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .77
Using the Markers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .78
Troubleshooting Hints . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .79
Making the Waveform (Time Domain) Measurement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .80
Purpose . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .80
Measurement Method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .80
Making the Measurement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .80
Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .81
Changing the Measurement Setup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .82
Changing the View . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .85
Using the Markers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .85
Troubleshooting Hints . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .86
Making the Tx Band Spur Measurement. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .87
Purpose . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .87
Measurement Method . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .87
Making the Measurement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .88
Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .89
Changing the Measurement Setup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .91
Changing the View. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .91
Troubleshooting Hints . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .92
4
1 Understanding GSM
5
Understanding GSM
What Is GSM?
What Is GSM?
The Global System for Mobile communication (GSM) digital
communications standard defines a voice and data over-air interface
between a mobile radio and the system infrastructure. This standard
was designed as the basis for a radio communications system. A base
station control center (BSC) is linked to multiple base transceiver
station (BTS) sites which provide the required coverage.
GSM 900, DCS 1800, and PCS 1900 are GSM-defined frequency bands.
The term GSM 900 is used for any GSM system operating in the
900 MHz band, which includes P-GSM, E-GSM, and R-GSM. Primary
(or standard) GSM 900 band (P-GSM) is the original GSM band.
Extended GSM 900 band (E-GSM) includes all the P-GSM band plus an
additional 50 channels. Railway GSM 900 band (R-GSM) includes all
the E-GSM band plus additional channels. DCS 1800 is an adaptation
of GSM 900, created to allow for smaller cell sizes for higher system
capacity. PCS 1900 is intended to be identical to DCS 1800 except for
frequency allocation and power levels. The term GSM 1800 is
sometimes used for DCS 1800, and the term GSM 1900 is sometimes
used for PCS 1900. For specifics on the bands, refer to Table 1-1.
The GSM digital communications standard employs an 8:1 Time
Division Multiple Access (TDMA) allowing eight channels to use one
carrier frequency simultaneously. The 270.833 kbits/second raw bit rate
is modulated on the RF carrier using Gaussian Minimum Shift
Keying (GMSK).
The standard includes multiple traffic channels, a control channel, and
a cell broadcast channel. The GSM specification defines a channel
spacing of 200 kHz.
6 Chapter1
Table 1-1 GSM Band Data
Understanding GSM
What Is GSM?
P-GSM
(GSM 900)
Uplink (MS Transmit)
Downlink (BTS Transmit)
Range (ARFCN)
TX/RX Spacing (Freq.)
TX/RX Spacing (Time)
Modulation Data Rate
Frame Period 4.615 ms 4.615 ms 4.615 ms 4.615 ms 4.615 ms Timeslot Period 576.9 µs 576.9 µs 576.9 µs 576.9 µs 576.9 µs Bit Period 3.692 µs 3.692 µs 3.692 µs 3.692 µs 3.692 µs Modulation 0.3 GMSK 0.3 GMSK 0.3 GMSK 0.3 GMSK 0.3 GMSK Channel Spacing 200 kHz 200 kHz 200 kHz 200 kHz 200 kHz TDMA Mux 88888 MS Max Power 20 W (8 W is
MS Min Power 13 dBm 5 dBm 0 dBm 0 dBm 0 dBm MS Power
Control Steps
Voice Coder
Bit Rate
890 to 915 MHz 880 to 915 MHz 876 to 915 MHz 1710 to 1785 MHz 1850 to 1910 MHz
935 to 960 MHz 925 to 960 MHz 921 to 960 MHz 1805 to 1880 MHz 1930 to 1990 MHz
1 to 124 0 to 124 and
45 MHz 45 MHz 45 MHz 95 MHz 80 MHz
3 timeslots 3 timeslots 3 timeslots 3 timeslots 3 timeslots
270.833 kbits/s 270.833 kbits/s 270.833 kbits/s 270.833 kbits/s 270.833 kbits/s
max in use)
0 to 15 2 to 19 2 to 19 0 to 15
13 kbits/s 13 kbits/s,
E-GSM
(GSM 900)
975 to 1023
20 W 20 W 20 W 20 W
5.6 kbits/s
R-GSM
(GSM 900)
1 to 124 and 955 to 1023
13 kbits/s 13 kbits/s 13 kbits/s
DCS 1800
(GSM 1800)
512 to 885 512 to 810
30, 31, 0 to 15
29,30,31
PCS 1900
(GSM 1900)
The GSM framing structure is based on a hierarchical system
consisting of timeslots, TDMA frames, multiframes, superframes, and
hyperframes. One timeslot consists of 156.25 (157) bit periods including
tail, training sequence, encryption, guard time, and data bits. Eight of
these timeslots make up one TDMA frame. Either 26 or 51 TDMA
frames make up one multiframe. Frames 13 and 26 in the 26 frame
multiframe are dedicated to control channel signaling.
These principles of the GSM systems lead to the need for the
fundamental transmitter measurements such as:
• Power vs. Time - which verifies that the transmitter output power
has the correct amplitude, shape, and timing for the TDMA
sequence.
Chapter 1 7
Understanding GSM
What Is GSM?
• Phase and Frequency Error - which verifies the accuracy of the
transmitters 0.3 GMSK modulation process.
• Output RF Spectrum - which verifies that the RF carrier is
contained within the designated 200 kHz channel.
Mobile Stations and Base Transceiver Stations
The cellular system includes the following:
• base transceiver stations, referred to as BTS
(frequency ranges dependent on the standard; refer to Table 1-1)
• mobile stations, referred to as MS
(frequency ranges dependent on the standard; refer to Table 1-1)
Uplink and Downlink
Uplink is defined as the path from the mobile station to the base
transceiver station. Downlink is the path from the base transceiver
station to the mobile station.
What Is an ARFCN?
An ARFCN is the Absolute Radio Frequency Channel Number used in
the GSM system. Each RF channel is shared by up to eight mobile
stations using Time Division Multiple Access (TDMA). The ARFCN is
an integer (in a range dependent on the chosen standard, refer to
Table 1-1) which designates the carrier frequency.
What are Timeslots?
GSM utilizes Time Division Multiple Access (TDMA) with eight time
slots per RF channel which allows eight users to use a single carrier
frequency simultaneously. Users avoid one another by transmitting in
series. The eight users can transmit once every 4.62 ms for 1 timeslot
which is 577 µs long. The eight user timeslots are numbered from 0 to 7.
Typically, each 577 µs timeslot has a length of 156.25 bit periods, which
consists of 148 data bits and 8.25 guard bits. The 4.62 ms required to
cycle through eight timeslots is called a frame. In a TDMA system, the
shape of each transmitted burst must be controlled carefully to avoid
over-lapping bursts in time.
8 Chapter1
Understanding GSM
What Does the Agilent Technologies E4406A VSA Series Transmitter Tester Do?
What Does the Agilent Technologies E4406A VSA Series Transmitter Tester Do?
The E4406A VSA Series Transmitter Tester makes measurements that
conform to the GSM 5.04, 5.05, 11.10, 11.21, and ANSI J-STD-007
specifications.
These documents define complex, multi-part measurements used to
maintain an interference-free environment. For example, the
documents include measuring the power of a carrier. The E4406A
automatically makes these measurements using the measurement
methods and limits defined in the standards. The detailed results
displayed by the measurements allow you to analyze GSM system
performance. You may alter the measurement parameters for
specialized analysis.
This instrument was primarily developed for making measurements on
digital transmitter carriers. These measurements can help determine if
a GSM transmitter is working correctly. The E4406A is capable of
measuring the continuous carrier of a base station transmitter.
For infrastructure test, the instrument will test base station
transmitters in a non-interfering manner by means of a coupler or
power splitter.
This instrument makes the following measurements:
• Transmit Power
• Power versus Time
• Phase and Frequency Error
• Output RF Spectrum
• Spectrum (Frequency Domain)
• Waveform (Time Domain)
• Tx Band Spur
Chapter 1 9
Understanding GSM
Other Sources of Measurement Information
Other Sources of Measurement Information
Additional measurement application information is available through
your local Agilent Technologies sales and service office. The following
application notes treat digital communications measurements in much
greater detail than discussed in this measurement guide.
• Application Note 1298
Digital Modulation in Communications Systems - An Introduction
part number 5965-7160E
• Application Note 1312
Understanding GSM Transmitter Measurements for Base
Transceiver Stations and Mobile Stations
part number 5966-2833E
Instrument Updates at www.agilent.com/find/vsa
This web location can be used to access the latest information about the transmitter tester.
10 Chapter1
2 Setting Up the GSM Mode
11
Setting Up the GSM Mode
GSM Mode
GSM Mode
At the initial power up, the transmitter tester will come up in the Basic
mode, with the Spectrum (Frequency Domain) measurement selected
and the Measure menu displayed.
To access the GSM measurement personality press the
select the
GSM softkey.
Mode key and
If you want to set the GSM mode to a known factory default state, press
Preset. This will preset the mode setup and all of the measurements to
the factory default parameters.
NOTE Note that pressing the Preset key does not switch instrument modes.
You may want to install a new personality, reinstall a personality that
you have previously uninstalled, or uninstall a personality option.
Instructions can be found in “Installing and Uninstalling Optional
Measurement Personalities” later in this section.
How to Make a Measurement
Follow the three-step process shown in the table below:
Step Primary Key Setup Keys Related Keys
1. Select & setup a mode
2. Select & setup a measurement
Mode Mode Setup, Input,
Frequency Channel
Measure Meas Setup Meas Control,
System
Restart
3. Select & setup view
View/Trace Span X Scale,
Amplitude Y Scale
Next Window, Zoom
12 Chapter2
, Display,
File
, Save,
Print, Print Setup,
Marker, Search
Setting Up the GSM Mode
GSM Mode
Changing the Mode Setup
Numerous settings can be changed at the mode level by pressing the
Mode Setup key. This will access a menu with the selections listed below.
These settings affect only the measurements in the GSM mode.
Radio
The
Radio key accesses a menu to select:
Band - select the GSM band (P-GSM, E-GSM, R-GSM, DCS 1800, or
•
PCS 1900). Refer to Table 1-1 on page 7 for GSM band data.
• Device - select the device to test BTS (Base Transceiver Station) or MS (Mobile Station).
• Freq Hopping - turn frequency hopping on or off.If frequency hopping is turned on, the instrument will ignore the bursts when the frequency is hopped off the selected channel frequency. Thus only valid data is included in the results. Only the Power vs. Time, and the Phase and Frequency Error measurements can be made on hopping GSM signals.
•
Carrier - select the type of carrier to measure (Burst or Continuous).
Radio Default Settings
Band P-GSM Device BTS Freq Hopping Off Carrier Burst
Chapter 2 13
Setting Up the GSM Mode
GSM Mode
Input
Input key accesses a menu to select the following. (You can also
The
access this menu from the front panel hardkey
Input Port - choose between RF, I/Q, I Only, 50 MHz Ref, and IF Align.
•
RF Input Range - To set the RF input range, choose Auto or Manual. If
•
Input.)
Auto is chosen, the instrument automatically sets the attenuator
based on the power level of the carrier (where it is tuned). If there
are multiple carriers present, the total power might overdrive the
front end. In this case you need to set the RF Input Range to Manual
and enter the expected maximum total power with the
Max Total Pwr
key. Manual is also used if you want to hold the input attenuation
constant (for the best relative power accuracy). For single carriers it
is generally recommended to set this to Auto.
•
Max Total Pwr - To set the maximum total power expected from the
UUT (Unit Under Test). This is the maximum expected value of the
mean carrier power referenced to the output of the UUT (may
include multiple carriers). The Max Total Pwr setting is coupled to
the input attenuator setting. If
Total Pwr is changed, RF Input Range is switched to Manual.
RF Input Range is set to Auto, and Max
Input Atten - To set the input attenuator setting. The input
•
attenuator setting is coupled to the Max Total Pwr setting. The
Input Atten softkey reads out the actual hardware value that will be
used for the current measurement. If more than one input
attenuator value is used in a single measurement, the value used at
the carrier frequency will be displayed. If
Auto, and Input Atten is changed, RF Input Range is switched to
Manual.
NOTE The Max Total Pwr and Input Atten settings are coupled together. When
you switch to a different measurement, the
constant, but the
Input Atten may change if the two measurements have
RF Input Range is set to
Max Total Pwr is kept
different mixer margins. Thus, you can directly set the transmitter
tester input attenuation, or you can set it indirectly by specifying the
maximum expected power at the UUT (Max Total Pwr setting).
14 Chapter2
Setting Up the GSM Mode
GSM Mode
• Ext Atten - To enter the external attenuator setting for either a BTS
or MS. This will allow the instrument to display the measurement
results referred to the output of the UUT.
•
IF Align Signal - This key has effect only when the Input Port key is set
to
IF Align. When IF Align is activated, the RF path is switched to
bring in the same alignment signal that is automatically switched in
to perform many alignments. This selection will allow manual
adjustment of the alignment signal for diagnostic purposes:
—
Signal Rate - The signal is modulated by a digital sequence that
can be set to 1 of 13 positions (rate 0 through 12) to cause the
comb spacing (or pulse timing) to widen or narrow. The key
reports the comb spacing for a given rate (0 to 12) in “kHz”.
—
Signal Amptd - This is the DAC control that changes the
amplitude of the signal. It is a 12 bit (0 to 4095) DAC. A higher
DAC number will raise the signal amplitude.
—
Signal Type - This can be CW (a tone that appears in the center of
the IF),
Comb, or Pulse.
Input Default Settings
Input Port RF RF Input Range Auto Max Total Power −15.00 dBm Input Atten 0.00 dB Ext Atten MS 0.00 dB Ext Atten BTS 0.00 dB IF Align Signal Rate 0 (= 468.75 kHz) IF Align Signal Amptd DAC 500 IF Align Signal Type CW
Chapter 2 15
Setting Up the GSM Mode
GSM Mode
Trigger
Trigger key allows you to select the following trigger source menus:
The
RF Burst
•
• Video (IF Envlp)
• Ext Front
• Ext Rear
Pressing one of the trigger source menu keys will access the trigger
mode setup menu. This menu is used to set the
Delay, Level, and Slope
for each trigger source. Note that the actual trigger source is selected
separately for each measurement (under the
Delay - For trigger delay use positive values. For pre-trigger use
Meas Setup key).
negative values.
Level - Forthe RF Burst selection the level is relative to the peak level
of the RF signal. For the
dBm at the RF input, that will cause the trigger. For the
Video selection the level is the value, in
Ext Front
and Ext Rear selections, the level range is −5 to +5 volts.
Slope Pos Neg - Choose to trigger off of the positive-going edge
(
Pos key) or the negative-going edge (Neg key) of the burst.
Other keys accessed under the
Trig Holdoff - Sets the period of time before the next trigger can occur.
•
Auto Trig - Acts as a trigger timeout. If no trigger occurs by the
•
Trigger key:
specified time, a trigger is automatically generated.
• Frame Timer - accesses the menu to manually control the frame
timer:
Period - sets the period of the frame clock
Offset - sets a one-time phase adjustment of the frame clock
Reset Offset Display - resets the display of offset key to 0
Sync Source - selects the source used to sync the frame timer
RF Sync Delay - In measurements that detect the GSM “T0”,
•
RF Sync Delay adjusts the “T0” point. This adjustment does not apply
if the
Burst Sync key is set to None,orifitissettoTraining Seq in the
Phase and Frequency Error measurement. The “T0” point is defined
as the time point of the transition from bit 13 to bit 14 of the
midamble training sequence for a given time slot.
•
Burst Search Threshold - Sets the threshold level used in the search
for GSM bursts after data is acquired. This is a relative level based
on the peak “on” power.
16 Chapter2
RF Burst
Delay
Peak Level
Slope
Video
Delay
Level
Slope
Ext Front
Delay
Level
Slope
Ext Rear
Delay
Level
Slope
Setting Up the GSM Mode
GSM Mode
Trigger Default Settings
0.000 s
−6.00 dB
Pos
0.000 s
−6.00 dBm
Pos
0.000 s
2.00 V
Pos
0.000 s
2.00 V
Pos
Trig Holdoff 0.000 s Auto Trig 100.0 ms Off
Frame Timer
Period
Offset
Reset Offset
Sync Source
RF Sync Delay 0.000 s
Burst Search Threshold −10.00 dB
250 µs
0.000 s
Display
Off
Demod
Burst Align - select the burst alignment between:
•
GSM - uses the burst alignment as defined in the GSM
specifications.
1/2 Bit Offset - shifts the burst alignment by 1/2 bit. This selection
applies to the Power vs. Time and the Phase and Frequency Error
measurements.
Demod Default Settings
Demod Burst Align GSM
Chapter 2 17
Setting Up the GSM Mode
GSM Mode
Changing the Frequency Channel
After selecting the desired mode setup, you will need to select the
desired ARFCN, center frequency, BMT frequency, burst type, and TSC
(Training Sequence Code). The selections made here will apply to all
measurements in the mode. Press the
the following menu:
ARFCN allows you to select the desired RF channel to be
measured. Refer to Table 1-1 on page 7 for the ARFCN
range for a specific GSM band.
Center Freq This is the current instrument center frequency. Use
this key to input a frequency that corresponds to the
desired RF channel to be measured.
BMT Freq allows you to select the Bottom, Middle, or Top of the
GSM (BTS transmit) band to be measured. This will
automatically select a specific center frequency and
ARFCN. Refer to the following table.
Frequency Channel key to access
Band Tx Band Edge
(MHz)
Low High Freq
P-GSM 935 960 935.200 1 947.600 63 959.800 124
E-GSM 925 960 925.200 975 942.600 38 959.800 124
R-GSM 921 960 921.200 955 940.600 28 959.800 124
DCS 1800 1805 1880 1805.20 512 1842.60 699 1879.80 885
PCS 1900 1930 1990 1930.20 512 1960.00 661 1989.80 810
Bottom Middle Top
(MHz)
ARFCN Freq
(MHz)
ARFCN Freq
ARFCN
(MHz)
18 Chapter2
Setting Up the GSM Mode
GSM Mode
Timeslot allows you to select the timeslot to be measured.
Timeslot numbers in the range of 0 to 7 can be selected.
Selection of the Timeslot is based on the position on the
screen−that is Timeslot 0 is defined to be at the start of
the data, and the data is divided into 8 timeslots (0 to
7). This key will be unavailable (grayed out) if a burst
type other than
Burst Type choose a GSM burst type from the following selections:
Normal (TCH & CCH) - Burst length = 148 bits
•
•
Sync (SCH) - Burst length = 148 bits
•
Access (RACH) - Burst length = 88 bits
TSC allows you to select the Training Sequence Code that
Normal is selected.
determines which timeslot is to be measured. This key
will be unavailable (grayed out) if a burst type other
than
Normal is selected, indicating the standard TSC is
used corresponding to the burst type.
•
Auto - In auto, the measurement is made on the first
burst found to have any one of the valid TSCs in the
range of 0 to 7. The measurement may be made on
various timeslots if more than one timeslot has one
of the 8 valid TSCs.
•
Man - In manual, the measurement is made on the
first burst found to have the selected TSC. TSC
numbers in the range of 0 to 7 can be selected. The
measurement may be made on various timeslots if
more than one timeslot has this same TSC.
When the GSM mode is selected, the instrument will default to the following settings.
Function Factory Default Setting
ARFCN <512 Center Frequency 942.600 MHz Timeslot 0 Off Burst Type Normal
(TCH & CCH)
TSC (Std) 0 Auto
Chapter 2 19
Setting Up the GSM Mode
GSM Measurement Key Flow
GSM Measurement Key Flow
The key flow diagrams, shown in a hierarchical manner on the
following pages, will help the user to grasp the overall functional
relationships for the front-panel keys and the softkeys displayed at the
extreme right side of the screen. The diagrams are:
“Mode Setup / Frequency Channel Key Flow” on page 21
“Transmit Power Measurement Key Flow” on page 22
“Power vs. Time Measurement Key Flow” on page 23
“Phase and Frequency Error Measurement Key Flow” on page 24
“Output RF Spectrum Measurement Key Flow” on page 25
“Spectrum (Freq Domain) Measurement Key Flow (1 of 3)” on
page 26
“Waveform (Time Domain) Measurement Key Flow (1 of 2)” on
page 29
View/Trace
QPSK EVM
<for EVM>
Avg Number 10 On|Off
“Tx Band Spur Measurement Key Flow” on page 31
Use these flow diagrams as follows:
• There are some basic conventions:
An oval represents one of the front-panel keys.
This box represents one of the softkeys displayed.
This represents an explanatory description on its specific key.
This box represents one of the default condition softkeys displayed.
Default conditions are shown as much as possible with underlined
parameters or values displayed on those softkey labels.
• Follow the measurement diagram from left to right and top to
bottom.
• A single softkey may allow multiple choices. For example; the
softkey reveals two choices, BTS or MS. The underlined choice is the
current state of the instrument. To change choices, press the softkey
one time.
• When entering a numeric value of
Frequency, for example, use the
numeric keypad and terminate the entry with the appropriate unit
selection from the softkeys displayed.
Device
• When entering a numeric value of
numeric keypad and terminate with the
Slot (Std), for example, use the
Enter front-panel key.
• Instead of using the numeric keypad to enter a value, it may be
easier to use the RPG knob or Up/Down keys.
20 Chapter2
Figure 2-1 Mode Setup / Frequency Channel Key Flow
GSMMode
Mode Setup
Frequency Channel
Radio
Band P-GSM, E-GSM, R-GSM, DCS 1800, PCS 1900
Device BTS | MS
Freq Hopping On |Off
Carrier Burst | Cont
Input
Input Port RF, I/Q, I only, 50 MHz Ref, IF Align
RF Input Range Auto| Man
Max Total Pwr -15.00 dBm
Input Atten 0.00 dB
Ext Atten
MS 0.00 dB
BTS 0.00 dB
IF Align Signal
Signal Rate
Signal Amptd
Signal Type CW, Comb, Pulse
Trigger
RF Burst
Delay 0.000 s
Peak Level -6.00 dB
Slope Pos| Neg
Video (IF Envlp)
Delay 0.000 s
Level -6.00 dBm
Slope Pos| Neg
Ext Front
Delay 0.000 s
Level 2.00 V
Slope Pos| Neg
Ext Rear
Delay 0.000 s
Level 2.00 V
Slope Pos| Neg
Trig Holdoff 0.000 s
Auto Trig 100.0 ms On | Off
Frame Timer
Period 4.615383 ms
Offset 0.000 s
Reset Offset Display
Sync Source Off, RF Burst, Ext Front, Ext Rear
RF Sync Delay 0.000 s
Burst SearchThreshold -10.00 dB
Demod
Burst Align
GSM
1/2 Bit Offset
ARFCN 38
Center Freq 942.600 MHz
BTM Freq Top, Middle, Bottom
Timeslot On | Off
Burst Type Normal, Sync, Access
TSC (Std) 0 Auto | Man
<Auto not for Spectrum>
<for EVM when Device is MS>
Setting Up the GSM Mode
GSM Measurement Key Flow
Chapter 2 21
Setting Up the GSM Mode
GSM Measurement Key Flow
Figure 2-2 Transmit Power Measurement Key Flow
Measure
Transmit Pwr
Meas Setup
Transmit PwrMeasure
Marker
Averages 50 On | Off
Avg Mode Exp | Repeat
Avg Type
Pwr Avg (RMS)
Log-Pwr Avg (Video)
Maximum
Minimum
Threshold Lvl -6.00 dB Abs |Rel
Trig Source
Free Run (Immediate)
Video (IF Envlp)
RF Burst (Wideband)
Ext Front
Ext Rear
Frame
Burst Sync None
Meas Time 1 Slot
Restore Meas Defaults
Advanced
RBW Filter Gaussian | Flat
Res BW 500.000 kHz
Select 1 | 2 | 3 | 4
Normal
Delta
Function
Band Power
Noise
Off
Trace
RF Envelope
I/Q Waveform
Off
Shape
Diamond
Line
Square
Cross
Marker All Off
22 Chapter2
Figure 2-3 Power vs. Time Measurement Key Flow
Setting Up the GSM Mode
GSM Measurement Key Flow
Measure
Pwr vs Time
Meas Setup
Pwr vs TimeMeasure
View/Trace
Avg Bursts 10On | Off
Avg Mode Exp | Repeat
Avg Type
Pwr Avg (RMS)
Log-Pwr Avg (Video)
Maximum
Minimum
Meas Time 1 Slot
Trig Source
Free Run (Immediate)
Video (IF Envlp)
RF Burst (Wideband)
Ext Front
Ext Rear
Frame
Burst Sync
Training Seq
RF Amptd
Restore Meas Defaults
Advanced
RBW Filter Gaussian | Flat
Res BW 508.000 kHz
Burst
Rise & Fall
Pwr vs TimeMeasure
Marker
Select 1 | 2 | 3 | 4
Normal
Delta
Function
Band Power
Noise
Off
Trace
RF Envelope
Upper Mask
Lower Mask
Off
Shape
Diamond
Line
Square
Cross
Marker All Off
Chapter 2 23
Setting Up the GSM Mode
GSM Measurement Key Flow
Figure 2-4 Phase and Frequency Error Measurement Key Flow
Measure
Phase & Freq
Meas Setup
Phase & FreqMeasure
View/Trace
Phase & FreqMeasure
Marker
Avg Bursts 10On | Off
Avg Mode Exp | Repeat
Avg Type
Mean
Maximum
Trig Source
Free Run (Immediate)
Video (IF Envlp)
RF Burst (Wideband)
Ext Front
Ext Rear
Frame
Burst Sync
Training Seq
RF Amptd
Restore Meas Defaults
I/Q Error (Quad-View)
I/Q Measured Polar Vector
Data Bits
Select 1 | 2 | 3 | 4
Normal
Delta
Function
Band Power
Noise
Off
Trace
Phase Error
Phase Error w/Freq
RF Envelope
Off
Shape
Diamond
Line
Square
Cross
Marker All Off
24 Chapter2
Figure 2-5 Output RF Spectrum Measurement Key Flow
Setting Up the GSM Mode
GSM Measurement Key Flow
Measure
Output RF Spectrum
Meas Setup
Output RF SpectrumMeasure
View/Trace
Avg Bursts 20 On | Off
Avg Mode Exp | Repeat
Meas Method
Meas Type
Ofs Freq List
Fast Avg On Off
Advanced
Modulation Numeric
Multi-Offset
Single Offset (Examine)
Mod & Switch
Modulation
Switching
Standard
Short
Custom
Restore Meas Defaults
Mod Avg
Pwr Avg (RMS)
Log-Pwr Avg (Video)
Modulation Meas BWs
Carrier RBW 30.000 kHz
< 1800 kHz Offset RBW 30.000 kHz
>= 1800 kHz Offset RBW 100.000 kHz
Switching Meas BWs
Carrier RBW 300 kHz
< 1800 kHz Offset RBW 30.000 kHz
>= 1800 kHz Offset RBW 30.000 kHz
Direct Time Break Freq 600.000 kHz
Output RF SpectrumMeasure
Marker
Select 1 | 2 | 3 | 4
Normal
Delta
Function
Band Power
Noise
Off
Trace
RF Envelope Modulation
RF Envelope Switching
Off
Shape
Diamond
Line
Square
Cross
Marker All Off
Chapter 2 25
Setting Up the GSM Mode
GSM Measurement Key Flow
Figure 2-6 Spectrum (Freq Domain) Measurement Key Flow (1 of 3)
Measure
Spectrum (Freq Domain)
Meas Setup
Span 1.00000 MHz
Res BW 20.0000 kHz Auto| Man
Average
Trig Source
Restore Meas Defaults
Advanced
Avg Number 25 On | Off
Avg Mode Exp | Repeat
Avg Type
Pwr Avg (RMS)
Log-Pwr Avg (Video)
Voltage Avg
Maximum
Minimum
Free Run (Immediate)
Video (IF Envlp)
RF Burst (Wideband)
Ext Front
Ext Rear
Frame
Line
Pre-ADC BPF On | Off
Pre-FFT Fltr Gaussian |Flat
Pre-FFT BW 1.55000 MHz Auto| Man
FFT Window Flat Top (High Amptd Acc)
Flat Top (High Amptd Acc)
Uniform
Hanning
Hamming
Gaussian (Alpha 3.5)
Blackman
Blackman-Harris
K-B 70 dB (Kaiser-Bessel)
K-B 90 dB (Kaiser-Bessel)
K-B 110 dB (Kaiser-Bessel)
FFT Size
Length CtrlAuto| Man
Min Pnts/RBW 1.300000
(a)
26 Chapter2
Setting Up the GSM Mode
GSM Measurement Key Flow
Figure 2-7 Spectrum (Freq Domain) Measurement Key Flow (2 of 3)
(a)
ADC Range
Auto
Auto Peak
AutoPeakLock
Manual
-6 dB
0 dB
+6 dB
+12 dB
+18 dB
+24 dB
Data Packing Auto, Short, Medium, Long
ADC Dither Auto On Off
Decimation 0 Auto Man
IF Flatness On Off
Spectrum (Freq Domain)Measure
View/Trace
Spectrum
Span X Scale
Span 1.00000 MHz
Amplitude Y Scale
Scale/Div 10.00 dB
Ref Value 0.00 dBm
Ref Position Top | Ctr | Bot
Scale Coupling On | Off
I/Q Waveform
Span X Scale
Scale/Div 18.8 us
Ref Value
Ref Position Left| Ctr | Right
Scale Coupling On | Off
Amplitude Y Scale
Scale/Div 60.0 mV
Ref Value 0.00 V
Ref Position Top |Ctr | Bot
Scale Coupling On |Off
Trace Display
All
Average (or Max & Min)
Current
Chapter 2 27
Setting Up the GSM Mode
GSM Measurement Key Flow
Figure 2-8 Spectrum (Freq Domain) Measurement Key Flow (3 of 3)
Spectrum (Freq Domain)Measure
Marker
Select 1 | 2 | 3 | 4
Normal
Delta
Function
Band Power
Noise
Off
Trace
Spectrum
Spectrum Avg
I/Q Waveform
Off
Shape
Diamond
Line
Square
Cross
Marker All Off
28 Chapter2
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