Design of Antennas for Handheld DVB-H ... - Lunds tekniska högskola

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2.1.5.1 Standardization of DVB-H The DVB-H system is not specified in one single document. Instead some modifications to other DVB specifications have been made (See figure 2.3). • The central specification is the DVB-H system specification EN 302 304. It has been published as the European norm for DVB-H. • The physical layer specification has been integrated in the DVB-T specification EN 300 744. This standard has been published as a new version, which contains the DVB-H physical layer enhancements in an annex. • Time slicing and MPE-FEC have been described in a new chapter of the DVB Data Broadcast specification EN 301 192. This document also defines the Multi-Protocol Encapsulation. • DVB-H-specific signaling has been integrated into the DVB Service Information (SI) specification EN 300 468. Figure 2.3. The connection between the different specifications defining DVB-H. The system specification determines mandatory and optional elements. The system specification is complemented by DVB-H implementation guidelines, which contain hints for the use and practical implementation of the standard. The DVB Project released these guidelines in the autumn of 2004 [12]. 10
2.1.5.2 Time slicing A large problem with handheld terminals is the limited battery capacity. It is impossible to receive and decode a broad band, high data-rate stream like the DVB-T data stream with a battery terminal. The receiver and demodulation part in the terminal would use too much power and the battery would run out quickly. In the beginning of the development of DVB-H it was shown that the power consumption of a DVB-T receiver is about 1 Watt, which is too much [14]. A some-what lower value seems possible but the desired target of 100 mW as a maximum threshold for the entire front end incorporated in a DVB-H terminal is still unobtainable for a DVB-T receiver. A considerable drawback for battery-operated terminals is the fact that with DVB- T, the whole data stream has to be decoded before any one of the services (TV programs) of the multiplex can be accessed. The main reason why DVB-H consumes less power is that the receiver only has to receive and process the parts of the data stream that contains the information needed for the selected service. For this to be possible the data stream needs to be reorganized in a suitable way. With DVB-H, service multiplexing is performed in a pure time-division multiplex. The data of one particular service are therefore not transmitted continuously but in compact periodical bursts with interruptions in between. In the interruption between bursts, other services are sent. This leads to a continuous data stream. This data stream can be received in time intervals where the receiver is synchronized with the service you want to receive. Then the receiver can be shut down when the other services that you have no interest in are sent. This way of dividing the signal is called time slicing [15]. When time slicing is used to receive the signal it saves a lot of power because the receiver can be turned off most of the time. When the receiver is on, the received signal is buffered in a memory and then read out from the buffer in the service data-rate. When the receiver is turned on the next time and receives a new data stream, this data is buffered in the memory and the video can be played continuously. For the receiver to know when it is time to turn itself on again after an off-time, data containing information about how long the receiver should be turned off between the bursts, has to be sent in each burst. The duration of one burst is in the range of several hundred milliseconds whereas the power save time may amount to several seconds. The receiver has to be turned on before it is time to receive data and therefore it is turned on 50-250 ms before calculated receiving time. Depending on the ratio between on time and off time, the resulting power saving may be more than 90 %. As an example, figure 2.4 shows a cut-out of a data stream containing time-sliced services. One quarter of the assumed total capacity of the DVB-T channel of 11
Page 1 and 2: Design of Antennas for Handheld DVB
Page 3 and 4: Acknowledgements This master thesis
Page 5 and 6: 4 DESIGN AND TESTING OF ANTENNA SOL
Page 7 and 8: Figure 5.2. Reference dipole antenn
Page 9 and 10: 1 Introduction The passed decade th
Page 11 and 12: 2 Background This chapter provides
Page 13 and 14: is simultaneously modulated into 10
Page 15 and 16: 2.1.3 Reed-Solomon Codes 2.1.4 DVB-
Page 17: 2.1.5 DVB-H DVB-H is the latest dev
Page 21 and 22: figure 2.5). All three elements tog
Page 23 and 24: symbols or four 2K OFDM symbols. Th
Page 25 and 26: 2.2 Competing standards The DVB-H s
Page 27 and 28: 2.3 Antenna theory This section des
Page 29 and 30: Figure 2.9. Impedance bandwidth def
Page 31 and 32: unloaded quality factor (Q0) and th
Page 33 and 34: losses should be avoided in handhel
Page 35 and 36: 3.3 Loop Figure 3.1. Yagi-Uda anten
Page 37 and 38: PIFA Figure 3.2. Four different con
Page 39 and 40: The size of the antenna is another
Page 41 and 42: 4.4 PIFA To verify the balun a resi
Page 43 and 44: 4.5 Folded-Patch With the PIFA-ante
Page 45 and 46: Figure 4.9a. Folded-patch 2, front
Page 47 and 48: Figure 4.11. Loop antenna schematic
Page 49 and 50: Figure 4.15. Wire loop antenna retu
Page 51 and 52: using an H-field antenna together w
Page 53 and 54: antenna. The dimension of the anten
Page 55 and 56: The result of the return loss measu
Page 57 and 58: Figure 4.24. Return loss graph for
Page 59 and 60: The result of the measurement of th
Page 61 and 62: Figure 4.31. Return loss graph for
Page 63 and 64: frequency band, the first from 470
Page 65 and 66: Figure 5.6. Radiation pattern for R
Page 67 and 68: 5.1.3 Measurement result In this ch
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Figure 5.10. Radiation pattern for
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Table 5.4. Switched monopole 1, gai
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Power gain / dB 2 0 -2 -4 -6 -8 -10
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was received in all five channels.
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6.3 Control signal 6.4 Cost The swi
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not be possible, there will always
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There are many advantages with tuna
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8 References [1] Schiller, Jochen -
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[29] Gardiol, Fred - Microstrip cir
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Design of Antennas for Handheld DVB-H ... - Lunds tekniska högskola

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