For a long time, we have had some subjects of Safety at the position to receive the UHF band microwave. This development is to solve the problem of securing Safety. This time, I succeeded in making a Small-sized Antenna compared with existing Antenna. As a result, we got improvements of safety and stable receive UHF band microwave.
The channel bandwidth of terrestrial television broadcasting is 6, 7 and 8MHz in the world. Digital terrestrial broadcasting system ISDB-T in Japan was originally developed as a system suitable for 6MHz bandwidth. But for international standardization, the system was extended to be suitable for 6, 7 and 8MHz bandwidth, and it was recommended in the ITU-R in 2000. This paper describes a multiband ISDB-T transmission system and the results of the laboratory experiments with a prototype receiver. In the AWGN channel, C/N-BER performance is same if the bandwidth is different. In the one multipath wave channel, the prototype receiver can equalize as expected when the multipath delay time is less than guard interval of each bandwidth ISDB-T system.
Distribution environment for audio and video content has changed dramatically, such as digital broadcasting service is widespread, the bandwidth available in the Internet access has been increasing, high-density storage media, e.g. DVDs and memory cards, have become inexpensive, and the number of personal computers (PCs) and mobile terminals have been growing rapidly. According this trend, variety of security technologies is required. I introduce some of them that are used in broadcasting services and content distribution services over the network.
It is necessary to establish the evaluation technology of the effect of application of SFN-GF (Single Frequency Network-Gap Filler) for the improvement of the poor reception of the digital terrestrial television broadcasting. In this report, the propagation analysis by the ray tracing algorithm was done in consideration of the direction characteristic of three dimensions and the rotation of the polarized electromagnetic radiation. And, we discussed the influence of interference for the case propagated attended with the rotation of the polarized electromagnetic radiation when the transmission signal reflected to the building.
Broadcasting signal reception techniques for UHF and VHF band are important since the mobile terminals for the Digital Terrestrial Television Broadcasting (DTTB) One-segment service and the multimedia broadcasting will be increased. In this paper, the DTTB signal is measured at low antenna height in high-rises. The receiving antenna is rotated in a horizontal direction. The signal is a non-Line-Of-Sight from the broadcasting station. The propagation paths are estimated from direction of arrival paths.
We developed an evolutional long-distance-delay-wave-distortion equalizing method under the SFN (Single Frequency Network) of terrestrial digital television network and confirmed that its performance is excellent. In this method, delay distortion is equalized by employing distortion compensation function (transfer function) which is produced by delay wave levels and delay times which are obtained by using conventional power spectrum method, polarity (lag or lead) of delay waves and carrier phase differences between the main wave and each delay wave which are obtained by newly developed method.
In a digital terrestrial broadcasting system that adopts OFDM (orthogonal frequency division multiplexing) method, echoes (multipath waves) outside the guard interval can distort the received signal and cause extreme degradation of the signal quality. Though DOA (direction of arrival) of an echo of high received level can estimate by rotating a receiving antenna, it is difficult to estimate DOA of multiple echoes of low received level especially outside the guard interval. Therefore, we have developed a DOA measurement method that uses a pair of receiving antennas without rotating. This method can even measure a delay profile of echoes outside the guard interval. Field experiments verified the performance of the method.