GSM Theory

The GSM System

The GSM System

The GSM system uses two frequency bands ranging from 890 to 915 MHz and 935 to 960 MHz. The bands are broken into 125 channels spaced 200 kHz apart.

The GSM system uses one band to transmit and one to receive. The lower frequency band (890-915 MHz) is used for the Mobile telephone to Base station link; the upper band is for Base to Mobile.

Channels from each band are used in uplink/downlink channel pairs. The channels in the channel pair are spaced 45 MHz apart.

The GSM system is time multiplexed, meaning that it is pulsed to allow multiple users access to the same channel. On each channel there are eight timeslots so that eight users can be on a channel at the same time. The pulses or timeslots are 576.9 μS long.

The GSM system has the capability of being frequency hopped within the frequency bands. This allows the system to hop the telephone to another channel and possibly another timeslot during a telephone call.

The GSM system uses a 0.3 Gaussian Minimum Shift Keying modulation scheme to modulate the digital data onto the pulsed carrier.

The digital data for one pulse is made up of both voice data and predefined data that is used for synchronization. The voice data is coded to maximize speech quality and minimize errors.

For most of the characteristics mentioned above the GSM system contains many variables. These variables account for the many screens and fields in the HP/Agilent 8922.

17-3

Page 237
Image 237
Agilent Technologies 8922 manual GSM System

8922 specifications

Agilent Technologies 8922 is a versatile and robust mobile communication test set, designed to fulfill the demanding requirements of wireless device manufacturers and service providers. Primarily focused on mobile radio communications, the 8922 provides a comprehensive solution for testing a wide array of signaling standards and technologies, making it essential in the rapidly evolving telecommunications landscape.

One of the standout features of the Agilent 8922 is its support for multiple wireless standards, including GSM, GPRS, EDGE, WCDMA, and HSPA. This makes the device an ideal choice for testing mobile devices that operate on different generations of cellular networks. Additionally, the 8922 is equipped with advanced measurement capabilities, allowing users to perform key performance indicators assessments, such as power, modulation quality, and spectral emission analysis, ensuring devices meet stringent regulatory and performance standards.

The 8922 is designed with an intuitive user interface that simplifies the setup and execution of tests. It features a large color display, making it easier for users to view test results and navigate through various functions. The built-in automation capabilities enable seamless integration into production environments, where efficiency and repeatability are crucial for high-volume testing.

Technologically, the Agilent 8922 incorporates advanced signal processing algorithms, which enhance its measurement accuracy and speed. The device's architecture allows for real-time analysis of signals, enabling users to identify issues quickly and efficiently. This is particularly important in the realm of mobile communications, where time-to-market is critical for competitive advantage.

Another significant characteristic of the 8922 is its flexible configuration options. Users can customize the test set with different hardware and software modules to suit specific testing needs. This scalability ensures that the 8922 remains relevant as wireless technologies evolve and new standards emerge.

In conclusion, the Agilent Technologies 8922 is an indispensable tool for professionals engaged in the testing of mobile communications devices. Its broad support for multiple standards, advanced measurement capabilities, user-friendly design, and flexibility make it a top choice in the telecommunications testing community. As the mobile communication industry continues to advance, the 8922 stands out as a leading solution for ensuring that devices meet quality and performance expectations.