Rohde & Schwarz CRTC02 Communications Test Sets
Features
CRTC02
Automatic Measurements and Logging Using Supplied Test Procedures
Built-in TTL Inputs/Outputs in the Transmit and Receive Path
Fast and Reliable Testing of Modules and Complete Mobile Stations
Automatic Test Routines
Simulate Base Station with Call Setup, Data Transfer and All Signaling Procedures Between CRTC02 and the Station-Under-Test
Log All Signaling Activities in OSI Layers 1, 2 and 3 for Protocol Analysis; Mnemonic Display of Message Content for Protocol Troubleshooting
Check Error-correction Facilities of the Mobile Station by Implanting Errors in the Data Stream
Transmitter Measurements:
Power Ramp and Phase Trajectory
Burst Delay
Frequency Error
Receiver Measurements:
Bit Error Rate in Real Time
Receiver Sensitivity
Speech Coder and Decoder Tests
Numerical and Graphical Output of Results
IEC/IEEE Bus Interface (Opt. 04)
Applications
Measurements on GMSK-modulated RF Signals and Receiver Testing
Testing for Compliance with GSM, DCS 1800 and PCS 1900 Recommendations
Simple Generation of Customized Test Procedures
Research and Development
Quality Assurance
CRTC02 Radiocommunications Test Set
The CRTC02 provides signal generation, signal measurement and user-friendly software. They are extremely powerful test sets, providing all simulation and analysis capabilities - from measurement of GSM/DCS 1800/PCS 1900-specific signals to detailed checking for hidden errors in signaling.
Signal Generation
The analog unit provides two independent RF generator channels. Using these two channels, the test set can simultaneously simulate and test a control channel (BCCH + FCCH + SCH + CCCH) and a traffic channel (TCH + SACCH). For measuring the receiver sensitivity, a fading simulator can be connected into each of the output circuits.
Transmission with or without frequency hopping is possible on all channels. The two channels are GMSK-modulated and are timed as bursts to occupy exactly one or all of the eight GSM/PCN time slots. The timing of the bursts can be adjusted and the amplitude can be varied dynamically over a 40 dB range.
Signal Measurement
A receive channel is allocated to each of the generator channels. It's offset by a duplex spacing of 45, 75 or 80 MHz relative to the generator channel, even under hopping conditions.
The digital signal is recovered by a precise GMSK demodulator. In addition, the signal in each of the receive channels is sampled. The phase and amplitude samples are stored and used for computing the signal parameters, such as burst delay, phase trajectory and power ramping.
User-friendly Software Saves
For development and quality control tasks, full flexibility is given by the possibility of varying procedures, signaling parameters and results display. For production testing, overview measurements and service tasks, complete test routines supplied with the equipment ensure reliable test results and ease of operation.
A menu-driven editor in conformance with coding rules 4.08 allows convenient entry of messages and system information simply by filling out tables.
A comfortable, window-oriented user interface simplifies the generation of test routines. Test programs are written in Borland Turbo C++. The use of this popular standard language eliminates the long training periods needed for special test languages and offers the user high flexibility.
The complete software, including message library, control programs and test results, is stored on a hard disk. The built-in floppy drive permits loading stored data and easy backup.
The digital unit may further be used as an IEC/IEEE controller, allowing extension of the test set by including external instruments. The test sets contain both the IEC/IEEE bus interface and the necessary software drivers.
Standard Measurements
The CRTC02 is supplied with an extensive test software package. These test programs are available in source code and can also be used as starter programs for generating user-specific programs by modifying programs or writing new ones.
The test routines fully comply with specifications:
Receiver sensitivity in speech channel (TCH/FS) and in user-data and control channels
Receiver input level range
Layer 2 signaling of mobile station
Call setup (mobile station originated and terminated call)
Absolute delay and timing advance
Delay measurement function
Intra-cell power change
Transmitter power control
Phase and frequency error
Power ramp of burst
In addition to the supplied software, other programs are available for test and measurements exactly in line with specifications for type-approval testing.
Signaling
The CRTC02 accurately simulates the functions of an ideal base station. For troubleshooting on the unit-under-test, the signaling parameters can also be varied.
All layer 1 channel coding, as well as layer 2 signaling, is automatically performed in real time. The layer 3 signaling sequence is defined by special test programs.
Protocol Analysis
Every transmitted or received layer 2 or layer 3 message, or even the bits of a burst, are marked with a frame number and recorded in the log memory. Depending upon whether everything is logged or just selected logical channels, the log can cover a interval between ten seconds and 15 minutes. The logged messages are displayed in mnemonic form on the screen, using the same basic mask as the message editor.
Burst Analysis
After data have been logged, power ramping as well as phase and frequency errors are calculated and displayed as a whole. Detailed analysis is supported by the zoom function.
To check the timing-advance measurement function of a mobile station, the CRTC02 measures the arrival of the burst and monitors the response of the mobile station to timing advance commands in the generator channels.
To check the delay measurement function of a base station, sending the burst can be delayed and the response of the station-under-test monitored.
To permit synchronization of external measuring instruments, a spectrum analyzer for example, the CRTC has a trigger output for automatically starting measurement at the beginning of a burst.
Testing Receiver Sensitivity
In the loop-back mode, bit error rates (BER) can be measured in real to test the receiver sensitivity of a mobile station.
The same test can be made on base stations by applying a signal modulated with a CCITT test pattern to the receiver input.
Acoustic Tests
These tests are supported by the built-in speech coder function and the Digital Audio Interface (DAI) of the mobile station as defined in Recommendation 11.10.III.6.4.
A serial EMMI is provided for remote control of the mobile station.
AF Measurements (Option 01)
A wide range of audio measurements can be performed on the AF section of the station-under-test. The AF generator provides single or double tones. The following measurement functions are implemented:
AF voltmeter with RMS or peak weighting
Continuously tunable distortion and SINAD meter
AF frequency counter
DC ammeter/voltmeter