1. Field in the Industry
The present invention concerns a system and a devise for transmission using an ultrawide band pass filter. In the present specification “ultrawide band” is abbreviated to “UWB”, “band pass filter” to “BPF” and thus, “ultra wide band pass filter” to “UWBPF”. The invention also concerns the device for the above-mentioned UWB transmission, namely, transmitters and receivers.
2. Prior Art
It is current trend that the band width of information transmission is getting wider to be ultra wide. UWB transmission system is a typical one of such trend. Trial has been made to carry out the transmission of at the rate of some Gbps at highest by using, not carrier wave, but short pulses of width of some nanoseconds or less. The frequency band used for this communication was set to be 3.1-10.0 GHz by FCC (Federal Communication Committee) of USA. For high quality transmission of UWB digital information using the frequency of this band width at a rate exceeding 1 Gbps an UWBPF of frequency range the same as that of the band of transmitting information is necessary.
To date, there has been no UWBPF covering such a wide band, and therefore, it has been tried to use a combination of plural BPFs of relatively narrow frequency bands. Combination of the plural BPFs of narrow frequency bands causes accumulated attenuation which results in necessity of high-power output at the side of signal source, or a problem of difficulty in timing the transmission due to difference in delay depending on the frequency bands. In order to avoid such problems it is inevitable to use a high performance waveshape forming filter at the sending side. The system shown in
The system of
Inventors succeeded in developing a small (for example, 50 mm×20 mm×1 mm) and low loss UWBPF having a frequency width of some GHz by forming a distribution constant circuit on a lossy substrate having low-pass filter function cutting high frequency components.
A prototype of the UWBPF was already disclosed (Japanese Patent Application 2003-008811). Then the inventors developed a UWBPF of more sharp frequency characteristics and established a comprehensive principal of the UWBPF, and disclosed (Saito et al., “Development of a BPF for UWB (3.1 GHz-10.6 GHz)”, Proceedings of the 2003 Communication Society, September, 2003). They expected that the newly developed UWBPF may realized the transmission system of the structure shown in
A practical example of the small, low-loss UWBPF is illustrated in
The object of the present invention is to provide a UWB transmission system using the above-mentioned, newly developed, small and low-loss UWBPF.
The transmission system of the present invention comprises: as shown in
As noted above, the communication standardized by FCC is carried out in the frequency range of 3.1-10.6 GHz, and therefore, the UWBPF is a BPF which passes the signal of this frequency range.
One part of the device for carrying out the present UWB transmission system is a transmitter comprising a short pulse generator generating sub-nanosecond pulse signal, a waveshape forming filter for band limiting, a UWBPF which passes signal of a predetermine frequency range, and a sending antenna. A practical device should contain an attenuator, which attenuates output of transmission so as to send signal in accordance with the legal regulations.
Another part of the device is a receiver comprising a receiving antenna, a UWBPF which passes signal of a predetermined frequency range, a pulse detector, and a determinator.
Both the transmitter and the receiver are, if they are used for the communication as standardized by FCC, the frequency range which the UWBPF passes must be, as noted above, 3.1-10.6 GHz.
According to the transmission system of the present invention, because the UWBPF used is of such a simple structure as being made by forming distribution constant circuit on a lossy substrate, the part of the UWBPF is of a small scale and low-loss, it is not necessary to use a high-power signal source at the transmitting side, and further, it is not necessary that the waveshape forming filter is precise and fine. Thus, the present invention enables UWB transmission using a small scale, low-cost device.
The UWBPF used in the present invention has such a wide band width as some GHz and such a low insertion loss as some dB's at 3 dB band width of the filter, and therefore, even if the frequency band of the transmitted signal which was waveshape-formed by waveshape forming filter of the transmitting side is wider than the predetermined band, it is possible to band-limit which the UWBPF, i.e., the waveshape forming may be flexibly altered depending on the circumstances. Thus, the transmission system according to the invention may have various applications in addition to the experiments described below.
An experimental device of the components shown in
Signal from the pulse generator is transmitted through the UWBPF to the receiving circuit. In the receiving circuit a synchronizing point is determined on the basis of known information signal series, and determination of 1/0 is carried out on the basis of the signal level at the synchronizing point. The output of the UWBPF and the input of the receiving circuit were connected with a coaxial cable. The output of the UWBPF was connected to a spectral analyzer and an oscilloscope.
The sending pulse and eye-pattern thereof after the signal of 1 Gbps, which was transmitted at a duty ratio of 50%, passed the UWBPF are shown is
Because the basic transmission characteristics were ascertained as described above, trial was made on a UWBPF, which was prepared by, as explained above, forming a distribution constant circuit on a lossy substrate having low-pass function cutting the high frequency components. The S21 characteristics of this UWBPF were determined to be as shown in
Number | Date | Country | Kind |
---|---|---|---|
2003-316916 | Sep 2003 | JP | national |