Passive telemetry system

Claim 2

A passive telemetry system comprising: a source of alternating current; a first magnetic coil connected to said source of alternating current; a second magnetic coil oriented for minimum magnetic coUpling with said first magnetic coil; indicating means responsive to voltage induced in second magnetic coil; and a passive sensing circuit comprising: a sensing device for modulating alternating current in response to a variable, a third magnetic coil connected to said sensing device, said third magnetic coil being disposed in spaced relation to said first magnetic coil and oriented for magnetic coupling therewith in order to supply alternating current to said sensing device; and a fourth magnetic coil connected to said sensing device, said fourth magnetic coil being disposed in spaced relation to said second magnetic coil and oriented for magnetic coupling therewith in order to transmit the modulated alternating current from said sensing device through said second magnetic coil to said indicating means.

Claim 3

The passive telemetry system of claim 1 wherein said first magnetic coil and said second magnetic coil are disposed adjacent each other and are oriented at substantially right angles to each other for minimum magnetic coupling therebetween.

Claim 4

The passive telemetry system of claim 2 wherein said third magnetic coil and said fourth magnetic coil are disposed adjacent each other and oriented at substantially right angles to each other for minimum magnetic coupling therebetween.

Claim 5

The passive telemetry system of claim 3 wherein said first magnetic coil and said third magnetic coil are disposed in substantially parallel spaced relation for maximum magnetic coupling therebetween.

Claim 6

The passive telemetry system of claim 4 wherein said second magnetic coil and said fourth magnetic coil are disposed in substantially parallel spaced relation for maximum magnetic coupling therebetween.

Claim 7

The passive telemetry system of claim 3 further comprising a switch disposed in the current path between said third magnetic coil and said fourth magnetic coil for interrupting the flow of current therebetween.

Claim 8

The passive telemetry system of claim 6 wherein said switching means comprises a magnetic reed switch operable by an external magnet and wherein said magnetic reed switch is located remote from said magnetic coils to avoid distorting the magnetic fields induced by said magnetic coils during the operation of said magnetic reed switch by said external magnet.

Claim 9

The passive telemetry system of claim 3 further comprising a standard element and switching means for substituting said standard element for said sensing device in said passive sensing circuit.

Claim 10

The passive telemetry system of claim 8 wherein said switching means comprises magnetic reed switch located remote from said magnetic coils so as to avoid disturbing the magnetic fields induced by said magnetic coils during the operation of said magnetic reed switch by an external magnet.

Claim 11

The passive telemetry system of claim 8 wherein said sensing device comprises a thermistor connected in series with said third magnetic coil and said fourth magnetic coil, and wherein said standard element comprises a standard resistance connected in parallel with said thermistor.

Claim 12

The passive telemetry system of claim 3 wherein said passive sensing circuit is encased within an inert substance suitable for implantation in a living animal.

Claim 13

A two-way signal transfer system comprising: a first magnetic coil for producing a magnetic filed in response to an electrical signal applied to its terminals, a second magnetic coil for producing an electrical signal at its terminals in response to changes in the magnetic flux produced by said first magnetic coil, said second magnetic coil having its axis disposed in substantially parallel spaced relation to the axis of said first magnetic coil for maximum magnetic coupling therebetween, a third magnetic coil for producing a magnetic flux in space in response to an electrical signal applied to its terminals, said third magnetic coil being adjacent said second magnetic coil and having its axis at substantially right to the axis of saiD second magnetic coil for minimum magnetic coupling between said third magnetic coil and said first and second magnetic coils, and a fourth magnetic coil disposed adjacent said first magnetic coil for producing an electrical signal at its terminals in response to changes in the magnetic flux produced by said third magnetic coil, the axis of said fourth magnetic coil being disposed at substantially right angles to the axis of said first magnetic coil and in substantially parallel spaced relation to the axis of said third magnetic coil for minimum magnetic coupling with said first and second magnetic coils and for maximum magnetic coupling with said third magnetic coil.

Claim 14

A two-way signal transfer system comprising: a first magnetic coil for producing a magnetic filed in response to an electrical signal applied to its terminals, a second magnetic coil for producing an electrical signal at its terminals in response to changes in the magnetic flux produced by said first magnetic coil, said second magnetic coil having its axis disposed in substantially parallel spaced relation to the axis of said first magnetic coil for maximum magnetic coupling therebetween, a third magnetic coil for producing a magnetic flux in space in response to an electrical signal applied to its terminals, said third magnetic coil being adjacent said second magnetic coil and having its axis at substantially right to the axis of saiD second magnetic coil for minimum magnetic coupling between said third magnetic coil and said first and second magnetic coils, and a fourth magnetic coil disposed adjacent said first magnetic coil for producing an electrical signal at its terminals in response to changes in the magnetic flux produced by said third magnetic coil, the axis of said fourth magnetic coil being disposed at substantially right angles to the axis of said first magnetic coil and in substantially parallel spaced relation to the axis of said third magnetic coil for minimum magnetic coupling with said first and second magnetic coils and for maximum magnetic coupling with said third magnetic coil.

Claim 15

The two-way signal transfer system of claim 12 wherein the plane of said first magnetic coil and said second magnetic coil is disposed in substantially parallel spaced relation to the plane of said second magnetic coil and said third magnetic coil.