Boots – shoes – and leggings
Patent
1991-04-30
1993-09-28
Mai, Tan V.
Boots, shoes, and leggings
364825, G06F 1531
Patent
active
052491455
DESCRIPTION:
BRIEF SUMMARY
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to transforming adaptors which are comprised of series and parallel circuits including a plurality of capacitors and a plurality of resistors which perform filter operation functions and a balancing network using wave digital filters which are include the transforming adaptors connected in cascade.
2. Description of the Related Art
It is advantageous to use wave digital filters when realizing balancing networks required in two-wire transmission systems for digital signals. This is because, compared with a general digital filter (represented by a cascade connection of an elementary digital filter section and expressed by a second order z function at the numerator and denominator) the correspondence with the balancing network made by passive elements in the analog domain is good and the requisite amount of memory may be reduced. Further, it is easy to obtain a reflected wave at an input terminal of the circuit, required as the output of the balancing network.
The method of designing a digital type balancing network using a wave digital filter is known. The present invention, however, proposes an improvement of the operating method of construction and an improvement of the characteristics.
As explained in more detail later, a wave digital filter type balancing network has various merits over a general digital filter, but suffers from the problem of a greater amount of filter operations per each basic sampling clock and therefore the size of the hardware becomes larger.
SUMMARY OF THE INVENTION
The present invention, in view of the above-mentioned problems with the prior art, has as its object the provision of a wave digital filter type balancing network which can reduce the amount of operations per basic sampling clock.
To achieve the above-mentioned object of the present invention, a wave digital filter is provided which comprises individual transforming adaptors, resistors, combined with respectively adjoining transforming adaptors to form a plurality of combined transforming adaptors and connecting the plurality of combined transforming adaptors in cascade. This enables a reduction of the amount of filter operations.
BRIEF DESCRIPTION OF THE DRAWINGS
The present invention will be explained below with reference to the appended drawings, wherein
FIG. 1 is a block circuit diagram of a balancing network;
FIG. 2 is a circuit diagram of a general analog ladder type balancing network;
FIG. 3 is a block diagram of a general wave digital filter type balancing network;
FIG. 4 is a block diagram of a first wave digital filter type balancing network according to the present invention;
FIG. 5 is a block diagram of a second wave digital filter type balancing network according to the present invention;
FIG. 6 is a block diagram of a first embodiment of the first wave digital filter type balancing network according to the present invention;
FIG. 7 is a circuit diagram of a first prototype analog ladder type balancing network;
FIG. 8 is a block diagram of a second embodiment of a second wave digital filter type balancing network;
FIG. 9 is a circuit diagram of a second prototype analog ladder type balancing network;
FIG. 10 is an equivalent wiring diagram showing a general format of a series 3-port pair adaptor;
FIG. 11 is an equivalent wiring diagram showing a general format of a parallel 3-port pair adaptor;
FIG. 12 is an equivalent wiring diagram showing a simplified format of a series 3-port pair adaptor;
FIG. 13 is an equivalent wiring diagram showing a simplified format of a parallel 3-port pair adaptor;
FIGS. 14A, 14B, 14C, and 14D are wiring diagrams showing the procedure for forming a combined transforming adaptor 41 of the present invention by combining the transforming adaptors 21 and 22 (first stage) of FIG. 3;
FIGS. 15A, 15B, and 15C are wiring diagrams showing the procedure for forming a combined transforming adaptor 41 of the present invention by combining the transforming adaptors 23 and 24 (second stage) of FIG. 3; a
REFERENCES:
patent: 3919671 (1975-11-01), Fettweis et al.
patent: 3967099 (1976-06-01), Fettweis
patent: 4192008 (1980-03-01), Mandeville
Brenner et al, "Analysis of Electric Circuits", copyright 1959 by McGraw-Hill Book Comp., Inc. p. 242.
Lawson, "Wave digital filter hardware structure", IEEE Proc., vol. 128, Pt. G, No. 6, Dec. 1981, pp. 307-312.
Denshi Joho Tsushin Gakkai Ronbunshi, Mar., 1987, vol. J70-A No. 3, pp. 491-499, "A Synthesis of Low-Sensitivity Digital Filters Using T-cascade Connection".
Denshi Joho Tsushin Gakkai Ronbunshi, Jun. 1986, vol. J69-A, No. 6, pp. 723-730, "On Equivalent Transformations and Sensitivity of Wave Digital Filters".
Fujitsu Limited
Mai Tan V.
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