Ultrasonic transmitting and receiving system for digital communication

• US 6,343,049 B1
• Filed: 09/19/2000
• Issued: 01/29/2002
• Est. Priority Date: 09/19/2000
• Status: Expired due to Fees

• Current Assignee: Toda, Kohji
• Original Assignee: Toda, Kohji
• Inventors: Toda, Kohji
• Primary Examiner(s): Lobo, Ian J.
• Application Number:
  US09/665,445
• Time in Patent Office: 497 Days
• Field of Search: 367/135, 367/137, 367/903, 342/42, 342/44, 455/39, 455/41, 455/91, 455/73, 310/313.B, 310/313.C, 310/313.D, 310/313.R, 310/318, 310/316.01
• US Class Current: 367/137
• CPC Class Codes: H04B 11/00 Transmission systems employing sonic, ultrasonic or infrasonic waves

Abstract

An ultrasonic transmitting and receiving system for digital communication comprises; a transmitting device including a first piezoelectric substrate, an input IDT, a first electrode-group, and an envelope detecting device; and a receiving device including a second piezoelectric substrate, an output IDT, a second electrode-group, an intermediary IDT, and an output IDT. Two neighbors of interdigital electrode pairs of the input IDT are at a distance L from each other. The first electrode-group consists of interdigital electrodes A₀ and A₁, at a distance L from each other. The second electrode-group consists of a central interdigital electrode B₀, a left interdigital electrode B₋₁ at a distance L₀ from the electrode B₀, and a right interdigital electrode B₁ at a distance L₀+L from the electrode B₀. The input- and output IDTs have coded patterns in reverse to each other. If a message digital-signal is applied to the input IDT, a first SAW is excited on the first piezoelectric substrate, and detected as a coded burst-signal at the electrode A₀, and then, at the electrode A₁ after a time corresponding to the distance L. Thus, a double-coded digital-signal is caused at the envelope detecting device, and delivered into a digital network. If the double-coded digital-signal is received at the electrodes B₁ and B₁ from the digital network, second- and third SAWs are excited on the second piezoelectric substrate, respectively, and transduced to a monocoded burst-signal at the electrode B₀. When the monocoded burst-signal arrives at the intermediary IDT, a fourth SAW is excited on the second piezoelectric substrate. If the fourth SAW corresponds to the first SAW, an output digital-signal equivalent to the message digital-signal is delivered from the output IDT.

Claims

1. An ultrasonic transmitting and receiving system for digital communication comprising:

a transmitting device consisting of;

an input terminal,

a first piezoelectric substrate,

an input IDT consisting of at least three interdigital electrode pairs Pi (i=1, 2, . . . , n), of which two neighbors are at a distance L from each other, and having a coded pattern,

a first electrode-group consisting of an interdigital electrode A₀ and an interdigital electrode A_i (i=1) at a distance iL (i=1) from said interdigital electrode A₀, said input IDT and said first electrode-group being formed on said first piezoelectric substrate,

an envelope detecting device,

an output terminal; and

a receiving device consisting of;

a receiving terminal,

a second piezoelectric substrate,

a second electrode-group consisting of a central interdigital electrode B₀, a left interdigital electrode B<sub>−

1</sub> at a distance L₀ from said central interdigital electrode B₀, and a right interdigital electrode B_i (i=1) at a distance L₀+iL (i=1) from said central interdigital electrode B₀,

an intermediary IDT,

an output IDT having a coded pattern in reverse to said input IDT, said second electrode-group, said intermediary IDT, and said output IDT being formed on said second piezoelectric substrate, and

a detecting terminal,

said input IDT exciting a first SAW on said first piezoelectric substrate when receiving a pulse (1) of a message digital-signal via said input terminal,

said interdigital electrode A₀ detecting a coded burst-signal corresponding to said first SAW,

said interdigital electrode A_i detecting said coded burst-signal after a time corresponding to said distance iL,

said envelope detecting device causing a double-coded digital-signal from said coded burst-signal at said interdigital electrode A₀ and that at said interdigital electrode A_i,

said output terminal delivering said double-coded digital-signal into a digital network,

said left interdigital electrode B<sub>−

1</sub> and said right interdigital electrode B_i exciting second- and third SAWs on said second piezoelectric substrate, respectively, when receiving said double-coded digital-signal from said digital network via said receiving terminal,

said central interdigital electrode B₀ transducing said second- and third SAWs to a monocoded burst-signal,

said intermediary IDT exciting a fourth SAW on said second piezoelectric substrate when receiving said monocoded burst-signal,

said output IDT delivering a decoded pulse (1), if said fourth SAW corresponds to said first SAW,

said detecting terminal detecting an output digital-signal, which is composed of said decoded pulse (1) and no detected pulse (0), and is equivalent to said message digital-signal.

2. An ultrasonic transmitting and receiving system for digital communication as defined in claim 1, wherein said coded pattern of said input- and output IDTs, respectively, is changed in accordance with a designated time region.

3. An ultrasonic transmitting and receiving system for digital communication as defined in claim 1, wherein a transmitting direction of said second- and third SAWs is orthogonal to that of said fourth SAW.

4. An ultrasonic transmitting and receiving system for digital communication as defined in claim 1, wherein

said first electrode-group includes at least two interdigital electrodes A_i {i=1, 2, . . . , (n− 1)} at a distance iL {i=1, 2, . . . , (n−

1)}, respectively, from said interdigital electrode A₀,

said second electrode-group includes at least two right interdigital electrodes B_i {i=1, 2, . . . , (n−

1)} at a distance L₀+iL {i=1, 2, . . . , (n−

1)}, respectively, from said central interdigital electrode B₀,

said at least two interdigital electrodes A_i take turns in connecting with said envelope detecting device, and at the same time,

said at least two right interdigital electrodes B_i take turns in connecting with said receiving terminal.

5. An ultrasonic transmitting and receiving system for digital communication as defined in claim 1, wherein said first- and second piezoelectric substrates are made of a piezoelectric ceramic, respectively, the polarization axis thereof being parallel to the thickness direction thereof.

6. An ultrasonic transmitting and receiving system for digital communication comprising:

a transmitting device consisting of;

an input terminal,

a first piezoelectric substrate,

a first input IDT consisting of at least three interdigital electrode pairs Pi (i=1, 2, . . . , n), of which two neighbors are at a distance L from each other, and having one coded pattern,

a second input IDT consisting of at least three interdigital electrode pairs Pi (i=1, 2, . . . , n), of which two neighbors are at a distance L from each other, and having the other coded pattern,

a first electrode-group consisting of an interdigital electrode A₀ and an interdigital electrode A_i (i=1) at a distance iL (i=1) from said interdigital electrode A₀, said first- and second input IDTs and said first electrode-group being formed on said first piezoelectric substrate,

an envelope detecting device,

an output terminal; and

a receiving device consisting of;

a receiving terminal,

a second piezoelectric substrate,

a second electrode-group consisting of a central interdigital electrode B₀,

a left interdigital electrode B<sub>−

1</sub> at a distance L₀ from said central interdigital electrode B₀, and an interdigital electrode B_i (i=1) at a distance L₀+iL (i=1) from said central interdigital electrode B₀,

an intermediary IDT,

a first output IDT having a coded pattern in reverse to said first input IDT,

a second output IDT having a coded pattern in reverse to said second input IDT, said second electrode-group, said intermediary IDT, and said first- and second output IDTs being formed on said second piezoelectric substrate, and

a detecting terminal,

said first- and second input IDTs exciting first- and second SAWs, respectively, on said first piezoelectric substrate when receiving pulses (0 and

     1), respectively, of a message digital-signal via said input terminal,

said interdigital electrode A₀ detecting a coded burst-signal corresponding to said first- and second SAWs, respectively,

said interdigital electrode A_i detecting said coded burst-signal after a time corresponding to said distance iL,

said envelope detecting device causing a double-coded digital-signal from said coded burst-signal at said interdigital electrode A₀ and that at said interdigital electrode A_i,

said output terminal delivering said double-coded digital-signal into a digital network,

said receiving terminal receiving said double-coded digital-signal from said digital network,

said left interdigital electrode B<sub>−

1</sub> and said right interdigital electrode B_i exciting third- and fourth SAWs, respectively, on said second piezoelectric substrate when receiving said double-coded digital-signal,

said central interdigital electrode B₀ transducing said third- and fourth SAWs to a monocoded burst-signal,

said intermediary IDT exciting a fifth SAW on said second piezoelectric substrate when receiving said monocoded burst-signal,

said first- and second output IDTs delivering decoded pulses (0 and

     1), respectively, if said fifth SAW corresponds to said first- and second SAWs, respectively,

said detecting terminal detecting an output digital-signal, which is based on said decoded pulses (0 and

     1) and is equivalent to said message digital-signal.

7. An ultrasonic transmitting and receiving system for digital communication as defined in claim 6, wherein said first- and second piezoelectric substrates are made of a piezoelectric ceramic, respectively, the polarization axis thereof being parallel to the thickness direction thereof.

8. An ultrasonic transmitting and receiving system for digital communication as defined in claim 6, wherein a transmitting direction of said third- and fourth SAWs is orthogonal to that of said fifth SAW.

9. An ultrasonic transmitting and receiving system for digital communication as defined in claim 6, wherein said coded pattern of said first- and second input IDTs, respectively, is changed in accordance with a designated time region, and at the same time, said coded pattern of said first- and second output IDTs, respectively, is also changed in response to a changed coded pattern of said first- and second input IDTs, respectively.

10. An ultrasonic transmitting and receiving system for digital communication as defined in claim 6, wherein

said first electrode-group includes at least two interdigital electrodes A_i {i=1, 2, . . . , (n− 1)} at a distance iL {i=1, 2, . . . , (n−

1)}, respectively, from said interdigital electrode A₀,

said second electrode-group includes at least two right interdigital electrodes B_i {i=1, 2, . . . , (n−

1)} at a distance L₀+iL {i=1, 2, . . . , (n−

1)}, respectively, from said central interdigital electrode B₀,

said at least two interdigital electrodes A_i take turns in connecting with said envelope detecting device, and at the same time,

said at least two right interdigital electrodes B_i take turns in connecting with said receiving terminal.

11. An ultrasonic transmitting and receiving system for digital communication as defined in claim 6 further comprising an input IDT in place of said first- and second input IDTs, said input IDT having two coded patterns, which are exchanged from each other in response to said pulses (0 and 1) of said message digital-signal applied to said input IDT.