As digital mobile TV continues to evolve toward mobile device applications, engineers in the fields of application development and system design are increasingly confronted with challenges such as miniaturization, reduced power consumption, and maintaining signal integrity. Among existing mobile TV standards, DVB-H has become a central focus for research. This article explores the opportunities and challenges in designing DVB-H receivers from a system-level perspective, with a particular emphasis on the RF front-end.
**Mobile TV Standards**
Table 1 outlines current and emerging mobile TV standards and systems, excluding cellular-based solutions like MBMS and BCMCS. While not exhaustive, it provides an overview of key technologies being used globally.
DVB-H is built upon the DVB-T standard and is backward compatible, allowing DVB-H signals to be transmitted over existing DVB-T channels. The major enhancements include the addition of a 4K FFT mode, deep interleaving for both 2K and 4K OFDM, an additional forward error correction layer (MPE-FEC) for multi-protocol encapsulation, and time slicing to reduce power consumption. Italy was one of the first countries to launch commercial DVB-H services, with many others planning to follow suit in 2007 and 2008.
In North America, Qualcomm developed FLO (Forward Link) technology, which underpins MediaFLO and operates with similar power-saving benefits through time slicing. Meanwhile, T-DMB, based on the Eureka 147 DAB standard, is widely used in South Korea. Another notable system is S-DMB, which uses Code Division Multiple Access (CDMA) and operates on a 25 MHz S-band channel, making it one of the few non-OFDM mobile TV systems.
Japan has been using the ISDB-T standard since 2006, delivering mobile TV services over a 6 MHz channel. China also introduced its own standard, CMMB (China Multimedia Mobile Broadcasting), which includes STIMi, a physical layer based on OFDM. Additionally, China adopted the DMB-TH standard for mobile TV services.
The DVB Steering Board recently approved the DVB-SH specification, which combines satellite and terrestrial networks to deliver mobile TV services. It offers two sub-standards: SH-A, where both satellite and terrestrial links use COFDM, and SH-B, where the satellite link uses TDM and the terrestrial link uses COFDM.
**RF Interface Requirements for DVB-H**
DVB-H is currently the leading mobile TV standard globally, and this article focuses on its design aspects. Table 2 summarizes key parameters related to the RF interface of mobile terminals.
Zero-IF direct conversion architectures have become popular for DVB-H due to their low power consumption and minimal external component requirements. However, low-IF designs face challenges with image rejection, especially in the presence of N+/-1 blockers. Advanced CMOS technology and mixed-signal correction techniques help mitigate issues like DC offset, while the high bandwidth and large subcarrier frequencies of DVB-H allow for effective spectrum management around the DC signal.
The TUA9000 demonstrates that even with a wide input frequency range, a low-noise amplifier (LNA) can be integrated into a pure CMOS tuner. With a system noise figure below 3.5 to 4 dB, the required sensitivity is easily met.
**Mobility**
The mobility of devices introduces dynamic channel conditions and Doppler shifts, which can impact signal quality. Receiver performance depends heavily on modulation schemes, protection methods, and signal processing algorithms. DVB-H is well-suited for these environments and can be configured to meet specific needs. Its strong AGC design and sufficient C/N margin ensure that the analog tuner section has minimal impact on overall performance.
**System Implementation Considerations**
Signal recovery in mobile environments often involves complex integration challenges. UHF receivers typically require high bandwidth, but the limited size of mobile antennas makes antenna design particularly difficult. Wideband antennas may suffer from lower gain, affecting the link budget. While low-noise receiver designs can help, the antenna remains the most critical component in the system.
Tuned or resonant antennas offer better performance, but nonlinear components like varactor diodes can degrade signal quality when exposed to strong GSM transmissions, especially when isolation between the cellular and DVB-H antennas is only 10–20 dB. Therefore, alternative antenna solutions should be considered to optimize system performance.
Nano High-frequency Transformer Iron Core
Our company's high-frequency transformer iron cores have very good quality.It can be widely used to the Inverter Welding machine power supply,X-ray, laser, communication power supply,UPS and high frequency induction heating power supply ,charging power supply,electrolytic and electroplate power supply,frequency control of motor speed power supply and plasma cutting machine.
Power Transformer Magnetic Ring,Low-Cost Iron Core,Plasma Cutting Machine Iron Core,Heating Power Supply Core
Anyang Kayo Amorphous Technology Co.,Ltd. , https://www.kayoamotech.com