A magnetic communication system includes a transmitter have a single coil transducer, and a receiver having a three orthogonally oriented coil transducers. The signal processing circuitry in the receiver adjusts the phases of the signals received by the three transducers to produce signals which are in-phase. The signals are then summed to provide an output signal from the receiver. The processing circuitry adjusts the phases of the incoming signals either serially or in parallel. transmissions from the receiver to the transmitter are also phase adjusted in accordance with the same adjustments used in reception.
|
0. 20. A method for communicating, the method comprising the steps of:
orienting each of multiple transducers along a unique axis to generate a magnetic field;
identifying a target receiver to which the magnetic field is transmitted; and
adjusting a phase output of the multiple transducers to produce the magnetic field for the target receiver.
0. 8. A method for communicating, the method comprising the steps of:
receiving an inductive input signal on each of multiple uniquely oriented transducers;
generating an electronic signal corresponding to the received inductive input signal for each of the transducers;
compensating for a relative motion of the transducers with respect to the inductive input signal by adjusting a phase of at least one of the electronic signals; and
summing the aligned electronic signals to produce an output signal that corresponds to the inductive input signal.
0. 27. A method for communicating, the method comprising the steps of:
receiving an inductive input signal on each of multiple uniquely oriented receiver transducers, the inductive input signal being received from a remote source transducer;
generating an electronic signal from each of the receiver transducers, each electronic signal corresponding to the inductive input signal;
based on a phase difference of the electronic signals, adjusting a phase of at least one of multiple transmitter transducers to produce an inductive output signal that is transmitted to a target receiver transducer near the remote source transducer.
0. 42. A method for communicating, the method comprising the steps of:
receiving an inductive input signal on each of multiple uniquely oriented receiver transducers, the inductive input signal being generated from a remote source transducer;
producing an electronic signal that corresponds to the inductive input signal for each of the receiver transducers, a level of each electronic signal being proportional to a strength of the received inductive input signal at a corresponding receiver transducer;
tracking a phase of each electronic signal during motion of the remote source transducer relative to the multiple uniquely oriented receiver transducers; and
based on the phase of at least one electronic signal, adjusting an inductive output signal from a transmitter transducer for communicating with a target receiver.
0. 54. A system for communicating, the system comprising:
multiple uniquely oriented receiver transducers, each of which receives an inductive input signal, the inductive input signal being generated from a remote source transducer;
a circuit coupled to the receiver transducers that produces an electronic signal corresponding to the inductive input signal for each of the receiver transducers, the phase of each electronic signal being a function of the position and orientation of the remote source relative to the multiple uniquely oriented receiver transducers;
a detection circuit that detects the phase of each electronic signal based upon a reception of the inductive input signal; and
a driver circuit that generates an inductive output signal from a based on the phase of at least one of the produced electronic signals.
4. A magnetic inductance communication system comprising:
a first transmission/reception coil producing a magnetic field including a transmitted signal;
a plurality of second transmission/reception coils having different orientations for receiving the transmitted signal and generating a plurality of received signals;
a plurality of amplitude determining circuits corresponding to the plurality of second transmission/reception coils for determining amplitudes of the plurality of received signals;
a modulator circuit for modulating a signal to be transmitted, wherein the modulator circuit includes:
a plurality of driving circuits each driving circuit receiving a carrier signal to be transmitted for generating a respective driving signal on one of the plurality of transmission/reception coils to generate a second magnetic field; and
a selection circuit for activating at least one of the driving circuits based upon the amplitudes of the received signals; and
signal processing circuitry connected to the first transmission/reception coil to receive the signal in the second magnetic field.
1. A magnetic inductance communications system, comprising:
a first transmission/reception coil producing a magnetic field including a transmitted signal;
a plurality of second transmission/reception coils having different orientations for receiving the transmitted signal and generating a plurality of received signals;
a summing circuit for combining the plurality of received signals to produce a summed signal;
at least one first phase adjusting circuit for adjusting a phase of at least one respective received signal prior to summing to increase the amplitude of the summed signal; and
a modulator circuit for modulating a signal to be transmitted, wherein the modulator circuit includes:
at least one second phase adjusting circuit receiving a carrier signal and a phase adjustment signal from the at least one first phase adjusting circuit;
a plurality of driving circuits, each driving circuit receiving the signal to be transmitted and a respective output signal from one of the second phase adjusting circuits, for generating a respective driving signal on one of the plurality of second transmission/reception coils to generate a second magnetic field; and
signal processing circuitry connected to the first transmission/reception coil to receive the signal in the second magnetic field.
2. The magnetic inductance communication system of
3. The magnetic inductance communication system of
5. The magnetic inductance communication system of
6. The magnetic inductance communication system of
7. The magnetic inductance communication system of
0. 9. A method as in
multiplexing each of the electronic signals to an error amplifier circuit and generating corresponding phase adjustment signals to align the electronic signals.
0. 10. A method as in
maintaining a phase adjustment of at least one electronic signal during which another electronic signal is monitored for generating a corresponding phase adjustment signal.
0. 11. A method as in
0. 12. A method as in
adjusting a polarity of one or more of the electronic signals so that the electronic signals have the same sign and sum to produce a larger output signal.
0. 13. A method as in
0. 14. A method as in
0. 15. A method as in
0. 16. A method as in
comparing a phase of each of the electronic signals with a common reference signal; and
controlling a local oscillator in a corresponding phase shifter to align the phase of each electronic signal with the reference signal.
0. 17. A method as in
generating an error signal that is used to adjust a phase of at least one electronic signal relative to a reference signal.
0. 18. A method as in
0. 19. A method as in
0. 21. A method as in
0. 22. A method as in
receiving the magnetic field on a single reception coil at the target receiver.
0. 23. A method as in
0. 24. A method as in
generating an electronic signal of information to be transmitted to the target receiver; and
multiplying the electronic signal with corresponding phase adjusted carrier frequencies to produce modulated signals and driving the transducers with the modulated signals to produce the magnetic field.
0. 25. A method as in
disposing the multiple transducers in a portable device.
0. 26. A method as in
coupling the portable device to a communications network.
0. 28. A method as in
0. 29. A method as in
0. 30. A method as in
0. 31. A method as in
0. 32. A method as in
0. 33. A method as in
0. 34. A method as in
0. 35. A method as in
0. 36. A method as in
multiplexing each of the electronic signals to an error amplifier circuit and generating corresponding phase adjustment signals to align the electronic signals; and
utilizing the phase adjustment signals to produce the inductive output signal.
0. 37. A method as in
maintaining a phase adjustment of at least one transmitter transducer during which another electronic signal is monitored for generating a corresponding phase adjustment signal for another transmitter transducer.
0. 38. A method as in
0. 39. A method as in
0. 40. A method as in
comparing a phase of each of the electronic signals with a common reference signal; and
controlling a local oscillator in a corresponding phase shifter to adjust the phase of each transmitter transducer with respect to the reference signal.
0. 41. A method as in
adjusting a phase of at least one of the multiple transmitter transducers compensates for a relative motion of the receiver transducers with respect to the inductive input signal.
0. 43. A method as in
0. 44. A method as in
0. 45. A method as in
0. 46. A method as in
detecting which of the multiple receiver transducers produces a strongest set of electronic signals; and
generating an inductive output signal from transmitter transducers oriented on similar axes as the receiver transducers that generate the strongest set of electronic signals.
0. 47. A method as in
adjusting at least one phase output of the transmitter transducers generating the inductive output signal for maximal reception at a target receiver transducer located near the remote source transducer.
0. 48. A method as in
comparing an amplitude of the electronic signals to determine which of the multiple uniquely oriented receiver transducers receives the strongest electronic signal.
0. 49. A method as in
0. 50. A method as in
0. 51. A method as in
0. 52. A method as in
0. 53. A method as in
0. 55. A system as in
0. 56. A system as in
0. 57. A system as in
0. 58. A system as in
a detection circuit that detects which of the multiple receiver transducers produces a strongest set of electronic signals; and
driver circuits to generate an inductive output signal from at least one of the transmitter transducers oriented on similar axes as the receiver transducers that generate the strongest set of electronic signals.
0. 59. A system as in
0. 60. A system as in
0. 61. A system as in
0. 62. A system as in
0. 63. A system as in
0. 64. A system as in
0. 65. A system as in
|
This is a continuation-in-part of U.S. patent application Ser. No. 08/444,017, filed May 18, 1995.
1. Field of the Invention
The present invention relates to magnetic communication systems. More particularly, it relates to a magnetic communication system which eliminates nulls in a mutual inductance field through a combination of signals from multiple transducers.
2. Discussion of the Related Art
When using a telephone, continually holding the handset to one's ear can be awkward. Also, holding the telephone interferes with the use of both hands for other work while trying to talk. In particular, the use of cellular telephones, which has increased dramatically, can interfere with the user's proper operation of an automobile. Various techniques have been used to overcome these difficulties.
Speaker phones allow one to talk while roaming around a room and using one's hands. However, speaker volume can disturb others around the user. They also cannot be used in close proximity to other speaker phones due to interference. They have limited privacy since the speaker broadcasts the conversation to all within earshot. Typically, the user must speak more loudly than normal to have proper reception at the microphone. Also, they tend to have poor sound quality because the user is not near the microphone and acoustics in the room are poor.
Headsets have been another way to free up the hands of a telephone user. Typically, the headset includes an adjustable strap extending across the user's head to hold the headset in place, at least one headphone located by the user's ear, and a microphone which extends from the headset along and around the user's face to be positioned in front of the users mouth. The headset is attached by a wire to the telephone. Headsets have the disadvantages of being bulky and somewhat awkward to use. Although they permit hands free use of the telephone, the user has limited mobility due to the connecting wire.
Wireless headsets have also been developed which eliminate the connecting wire to the telephone. The wireless headset uses radio frequency (RF) technology or infrared technology for communicating between the headset and a base unit connected to the telephone. The need for communications circuitry and sufficient power to communicate with the base unit increases the bulk and weight of the headset. This increased weight can become tiresome for the user. One alternative has been to attach the headset by a wire to a transmitting unit worn on the belt of the user. As with wired headsets, the wire can become inconvenient and interfere with other actions by the user. Significant interference rejection circuitry is also needed when multiple wireless headsets are used in close proximity.
Magnetic induction fields can be used to provide a communication link between a base unit and a headset. However, magnetic induction fields suffer from signal nulls at certain positions and orientations between the transmitter and receiver. When performing magnetic communications, a specific position and orientation between the transmitter and receiver is typically required. With a single transducer at the transmitter and receiver, certain positions and orientations result in no signal being received due to nulls in the mutual inductance between the transducers. The signal can be recovered by reorienting one of the transducers. It is also possible to use multiple, orthogonally positioned coils at the transmitter or receiver so that at least one coil does not have a null. Different mechanisms have been used to select or combine outputs from the transducers in order to provide communications.
In U.S. Pat. No. 4,489,330, a four coil transducer receiver includes a mercury switch array for selecting a coil transducer. As the receiver is moved, the switch array activates to pick up the positive phase components from the coils. However, this system cannot compensate for changes in position and orientation of the transmitter, and, thus, requires a stationary transmitter. Also, the mercury switch array is large, costly, and sometimes unreliable. Furthermore, switching transients occur as different coils are selected, which causes degradation of the signal and possible loss of information.
In U.S. Pat. No. 4,967,695, a three axis magnetic induction system used as a proximity detector is described. In this system, the outputs of the three coils are combined to provide a single received signal. While this system eliminates switching transients, it has other deficiencies. Since the output signal reverses polarity when it is rotated 180 degrees, the summed signal can be zero in some situations. Thus, the nulls present in the single transducer system are merely repositioned. Furthermore, the simple summing of signals from all three transducers can increase noise levels. For a proximity detector, noise is not a significant concern because it is merely attempting to determine the existence of a signal. Much better signal to noise ratios are needed in order to receive communication signals.
The deficiencies of prior art systems are overcome in great part by the present invention which, in one aspect, includes a short-range, wireless communication system including a miniaturized portable transceiver and a base unit transceiver. The miniaturized portable transceiver sends and receives information through magnetic induction to the base unit, which may also be portable. Similarly, the base unit sends and receives information through magnetic induction to the portable transceiver. The information can be voice, data, music, or video. Use of magnetic induction fields reduces the power requirements and thus allows a smaller size and greater convenience.
In another aspect of the present invention, the base unit or portable device may include multiple, orthogonally arranged transducers for generating multiple magnetic fields. The multiple fields substantially eliminates mutual inductance nulls between the base unit and portable unit which result at certain positions in a generated field. In another aspect of the present invention, the multiple transducers may be selectively operated based upon a strongest signal, in order to limit power consumption and improve signal reception. The signals from the transducers are electronically scanned. The signals are then phase adjusted and combined to achieve a maximum signal level. In another aspect of the invention, the same phase information is used for a transmitted signal. This allows the other device to use a single transducer while maintaining a high signal to noise ratio.
In another aspect of the present invention, the magnitude of the incoming signals is used for selective transmission on one or more of the transmission transducers. The amplitude of the signal from each of the transducers is determined. This amplitude information is used for selecting one or more drivers for the transmission transducers corresponding to the greatest amplitude.
In another aspect of the present invention, a headset contains the miniaturized transceiver which communicates with the base unit through magnetic induction fields. In another aspect of the present invention, the headset may be of the concha type in which the speaker fits into the user's ear without a strap across the head and the transceiving transducer is encapsulated into the microphone boom which is short and straight along the user's cheek. In another aspect of the invention, the base unit may be a portable telephone, which can be attached to the user, to further transmit communications from the wireless communication system to a cellular telephone network or a cordless telephone unit.
In another aspect of the invention, the communication system is half-duplex where the base and headset alternatively transmit and receive digital audio. In another aspect the communication system is a simplex system where the receiver has multiple transducers.
With these and other objects, (a) advantages and features of the invention that may become apparent, the nature of the invention may be more clearly understood by reference to the following detailed description of the invention, the appended claims and the several drawings attached hereto.
As illustrated in
The portable device 2 as a headset 20 is illustrated more fully in FIG. 3. It includes a body portion 23 which houses a transducer 40 and processing circuitry. A speaker 22 is connected to the circuitry within the body 23. An earpiece 21 next to the speaker 22 fits in the user's ear to hold the unit in place and to allow the user to hear sounds from the speaker. A microphone boom 24 extends from the body 23 several inches in order to place a microphone 25, located at the end of the boom 24, close to the user's mouth. Alternatively the transducer 40 may be housed in the boom 24. A rechargable battery 51 is also housed in the body 23 of the headset 20 to provide power to the headset. Other features may be optionally included in the headset 20, such as switcher or buttons for manually activating different modes. For example, a capacitive switch or push-button could be used to cause the headset 20 to transmit a control signal to the portable phone 10 to activate muting of the microphone. The portable phone 10 may include a receptacle 19 for receiving and holding the headset 20. Depositing the headset in the receptacle can provide a variety of functions, in addition to maintaining the headset 20 and portable phone 10 together. A switch can be disposed in the receptacle to terminate the telecommunication when the headset 20 is inserted or initiate the telecommunication when it is removed. The receptacle may also include connections to recharge the battery 51 in the headset 20.
The base unit 1 and portable device 2 communicate through amplitude modulation of inductive fields, although other modulation methods such as frequency, phase, or digital modulation could be employed. During use, the distance between the portable device 2 and the base unit 1 typically is short. Since the distance is short, only an inductive field is necessary, and little or no radiation occurs. This limits the operating power, which allows a smaller size and weight for the rechargable battery 51 and, thus, the portable device 2. Furthermore, it limits interference between systems operating in close proximity. Therefore, interference rejection circuitry may be limited or not necessary in the portable device 2.
The transducer system in the portable device 2 is illustrated schematically in FIG. 4. The transducer 40 preferably includes a ferrite rod transducer having a ferrite rod 41 within a wire coil 42. The wires from the transducer 40 are connected to a transceiver 27 having transmitter electronics 28 and receiver electronics 29. The transceiver 27 connects to the portable device electronics 26, the nature of which is dependent upon the function of the portable device 2. In the example of the portable device as a headset 20, the portable device electronics would connect to a speaker 22 and a microphone 25. Transmission and reception can occur at different frequencies, which permits full duplex operation. Alternatively, separate transmitting and receiving transducers can be used.
The base unit 1 configuration is illustrated schematically in FIG. 5. The transducer system 30 includes three orthogonally disposed ferrite rod transducers, each including a ferrite rod 31, 32, 33 and a respective coil 34, 35 and 36. The use of the orthogonally disposed transducers overcomes the occurrence of mutual inductance nulls in the resulting inductive fields. The three transducers are connected to multiplexer electronics 60 for selecting one or more of the transducers for transmission and reception. Circuitry in the multiplexer electronics may be used to select the transducer or transducers having the strongest signal for transmission and reception to reduce the total power consumption of the device. Circuitry can also be used to control the phases of signals from each of the transducers for combining the signals. Thus, the phases should be continuously adjusted to provide a maximum signal level. Alternatively, a non-zero signal can be attained simply be revising the phase of one or more signals so that all signals have the same sign.
The transmitter electronics 61 and receiver electronics 62 provide for processing of the communications signals from the base unit electronics 70 and the portable device 2. As discussed above, for a portable telephone 10, the conventional telephone speaker 71 and mouthpiece 72 may be eliminated so that the portable telephone 10 solely uses the headset 20 through the transducer system for communicating to the user. Switching circuitry (not shown) would be included to select between the speaker 71 and microphone 72, and the headset 20. The switching circuitry could be included in the receptacle 19 so that the speaker 71 and microphone 72 are disconnected when the headset 20 is removed.
The phase adjusted signals are also processed to maintain maximum signal strength through the phase adjustment process. Various processes can be used to adjust phases. As noted above, one problem with merely summing signals from different transducers is that the signals can have different polarities which can cancel the signals when summed. One possible phase adjustment is to change polarities of signals. The polarity of each of the signals is determined. Then, the polarity of one or more signals is changed by the phase shifters 120, 121, 122 so that the polarities are always the same. Thus, when the signals are combined by the summing amplifier 111, they never cancel each other and a maximum signal is achieved.
According to the embodiment of the invention illustrated in
Alternatively, if the coils are likely to be moving more quickly than can be tracked through serial phase adjustment, a phase adjusting circuit can be applied separately to each of the coils. This embodiment is illustrated in FIG. 7. Each of the mixers 108, 109, 110 is connected to a separate IF filter 114, 123, 124 and amplifier 115, 125, 126 to measure the phase of the signal received at the respective coil. Each phase is then compared with a reference phase by mixing the signal with the output of a local oscillator. Since the same oscillator is used for the signals from each of the coils, the signals will remain in phase with each other. The mixed signal from the mixers 116, 127, 128 are passed through respective low pass filters 117, 129, 130 and error amplifiers 118, 131, 132 to provide error signals representing the difference between the phase of the received signal at each coil and the reference phase. The error signals are applied to the phase shifters 120, 121, 122 to adjust the phases of each of the received signals to maintain the phase coincidence for summing. As in the prior embodiment, the phase adjusted signals are combined by the summing amplifier 111 and further processed by the signal processing circuits 112 to provide an output from the base unit 1.
The phase adjustment information used in receiving signals can also be used in driving transmission signals to provide a maximum signal level at the receiver location. Since the phases of the incoming signals are adjusted to achieve a maximum signal level, the phase adjustments define the position and orientation of the transmitting coil. The same phase adjustments on transmission compensate for this position and orientation. Thus, a single reception coil can be used. According to an embodiment of the invention, the base unit 1 includes three orthogonally positioned coil transducers with phase adjusting circuitry for both reception and transmission. The portable device, therefore, only requires a single coil transducer and can be made smaller in size. As illustrated in
Additionally, the transmission system can be used for charging the battery 51 of the portable device 2. The base unit 1 includes a battery charger signal generator 52 connected to the transmitter 61. This generator 52 produces a recharging signal which is sent through one of the ferrite rod transducers in the base unit 1 to the ferrite rod transducer 40 of the portable device 2. Since in the telephone embodiment of
Although the communication system of the present invention has been illustrated in connection with a concha type headset 20 and a cellular or cordless telephone handset 10 as a base unit 1, it is readily adaptable for other types of headsets and uses. The headset can be of the over-the-head type, over-the-ear type, or binaural type. The system can be used as a wireless connection to a conventional desktop telephone. Such a system would operate in the manner discussed above with the cordless bandset. Since several such units may be used in close proximity, interference may become more of a problem. Therefore, the system can be designed to operate on various frequencies and can select frequencies for the transmission and reception which are unlikely to have significant interference. Similarly, the system can be used with a computer, either stationary or portable, for voice data entry, sound transmission, and telephone functions. The system can also be used with other types of communication systems, including personal digital assistants (PDAs), cordless phones, PCS and SMR cellular phones, two way (video games), two-way half duplex (walkie-talkies, CBs), or two-way full duplex (phones), one way simplex headphones. When the base unit is stationary and the user is likely to be at certain locations relative to the base unit, fewer transducers may be used in the base unit without encountering mutual inductance nulls. Alternative transducer systems may also be used for generating the inductive fields. Specifically, rather than a single transducer for transmission and reception on different frequencies, separate transducers may be used.
Having thus described one illustrative embodiment of the invention, various alterations, modifications, and improvements will readily occur to those skilled in the art. Such alterations, modifications, and improvements are intended to be within the spirit and scope of the invention. Accordingly, the foregoing description is by way of example only and is not intended as limiting. The invention is limited only as defined in the following claims and equivalent thereto.
Cobler, Patrick J., Butler, Neal R., Palermo, Vincent
Patent | Priority | Assignee | Title |
10038475, | Aug 29 2014 | FREELINC HOLDINGS, LLC | Proximity boundary based communication using radio frequency (RF) communication standards |
10084512, | Aug 29 2014 | FREELINC HOLDINGS, LLC | Proximity boundary based communication |
10103786, | Mar 22 2011 | FREELINC HOLDINGS, LLC | System and method for close proximity communication |
10117050, | Nov 08 2010 | FREELINC HOLDINGS, LLC | Techniques for wireless communication of proximity based content |
10122414, | Aug 29 2014 | FREELINC HOLDINGS, LLC | Spatially enabled secure communications |
10164685, | Dec 31 2014 | FREELINC HOLDINGS, LLC | Spatially aware wireless network |
10594368, | Jan 31 2019 | Capital One Services, LLC | Array and method for improved wireless communication |
11342964, | Jan 31 2019 | Capital One Services, LLC | Array and method for improved wireless communication |
11581918, | Aug 08 2007 | FREELINC HOLDINGS, LLC | Near field communications system having enhanced security |
8880100, | Mar 23 2011 | FREELINC HOLDINGS, LLC | Proximity based social networking |
8929809, | Mar 22 2011 | FREELINC HOLDINGS, LLC | Techniques for wireless communication of proximity based content |
9400985, | Nov 08 2010 | FREELINC HOLDINGS, LLC | Techniques for wireless communication of proximity based content |
9455771, | Mar 22 2011 | FREELINC HOLDINGS, LLC | System and method for close proximity communication |
9560505, | Mar 23 2011 | FREELINC HOLDINGS, LLC | Proximity based social networking |
9621227, | Aug 29 2014 | FREELINC HOLDINGS, LLC | Proximity boundary based communication using radio frequency (RF) communication standards |
9621228, | Aug 29 2014 | FREELINC HOLDINGS, LLC | Spatially aware communications using radio frequency (RF) communications standards |
9705564, | Aug 29 2014 | FREELINC HOLDINGS, LLC | Spatially enabled secure communications |
9780837, | Aug 29 2014 | FREELINC HOLDINGS, LLC | Spatially enabled secure communications |
9838082, | Aug 29 2014 | FREELINC HOLDINGS, LLC | Proximity boundary based communication |
Patent | Priority | Assignee | Title |
3617890, | |||
3898565, | |||
4061972, | Dec 03 1974 | Short range induction field communication system | |
4117271, | Jan 10 1977 | The United States of America as represented by the Secretary of the Navy | Inductive communication system |
4160952, | May 12 1978 | Bell Telephone Laboratories, Incorporated | Space diversity receiver with combined step and continuous phase control |
4298874, | Oct 18 1976 | KAISER AEROSPACE & ELECTRONICS CORPORATION, A CORP OF NV | Method and apparatus for tracking objects |
4320342, | Sep 15 1978 | U S PHILIPS CORPORATION, A CORP OF DE | Magnet coil arrangement for generating linear magnetic gradient fields |
4334316, | Oct 31 1979 | Nippon Electric Co., Ltd. | Pre-detection maximal ratio combining system for diversity reception of radio frequency signals |
4373207, | Dec 17 1980 | Bell Telephone Laboratories, Incorporated | Space diversity signal combiner |
4442434, | Mar 13 1980 | BANG & OLUFSEN A S 7600 STRUER, DENMARK | Antenna circuit of the negative impedance type |
4489330, | Oct 01 1981 | Rion Kabushiki Kaisha | Electromagnetic induction coil antenna |
4513412, | Apr 25 1983 | AT&T Bell Laboratories | Time division adaptive retransmission technique for portable radio telephones |
4542532, | Mar 09 1984 | Medtronic, Inc. | Dual-antenna transceiver |
4584707, | Jan 22 1985 | DNE TECHNOLOGIES, INC ; ESSEX TECHNOLOGY, INC | Cordless communications system |
4600829, | Apr 02 1984 | Electronic proximity identification and recognition system with isolated two-way coupling | |
4642786, | May 25 1984 | POSITION ORIENTATION SYSTEM, LTD | Method and apparatus for position and orientation measurement using a magnetic field and retransmission |
4647722, | Sep 28 1984 | Aisin Seiki Kabushiki Kaisha; Toyoda Gosei Co., Ltd. | Land mobile telephone system |
4654883, | Oct 18 1983 | Iwata Electric Co., Ltd. | Radio transmitter and receiver device having a headset with speaker and microphone |
4669109, | Feb 26 1985 | Telephone apparatus with a fixed telephone station coupled to a mobile and detachable handset | |
4733402, | Apr 23 1987 | Sundstrand Corporation | Adaptive filter equalizer systems |
4747158, | Dec 13 1985 | DNE TECHNOLOGIES, INC ; ESSEX TECHNOLOGY, INC | Cordless communications system |
4752776, | Mar 14 1986 | IDESCO OY, A CORP OF FINLAND | Identification system |
4918737, | Jul 07 1987 | SIEMENS AKTIENGESELLSCHAFT, A CORP OF GERMANY | Hearing aid with wireless remote control |
4939791, | Dec 09 1987 | Blaupunkt Werke GmbH | Diversity radio receiver for use with multiple antenna, particularly car radio |
4967695, | Jun 23 1989 | INNOTEK, INC | System for controlling the movement of an animal |
5054112, | Mar 16 1988 | Seiko Instruments Inc | Electronic data collection system |
5097484, | Oct 12 1988 | Sumitomo Electric Industries, Ltd. | Diversity transmission and reception method and equipment |
5276686, | Oct 17 1990 | Kabushiki Kaisha Toshiba | Mobile radio communication system having mobile base and portable devices as a mobile station |
5276920, | Jan 18 1990 | Nokia Mobile Phones Ltd. | Antenna selection switch for a diversity antenna |
5390357, | Aug 28 1991 | NEC Corporation | Power saving diversity receiver |
5437057, | Dec 03 1992 | Xerox Corporation | Wireless communications using near field coupling |
5453686, | Apr 08 1993 | CHITTENDEN BANK | Pulsed-DC position and orientation measurement system |
5457386, | Nov 26 1991 | Hitachi Medical Corporation | Multiple-coil adopting a quadrature detection method applied thereto and a signal processing circuit employing the same in an MRI apparatus in a vertical magnetic system |
5553312, | Jun 20 1994 | ACS WIRELESS, INC | Data transfer and communication network |
5568516, | Jul 02 1993 | Phonic Ear Incorporated | Very low power cordless headset system |
5581707, | Jul 27 1994 | PSC, Inc. | System for wireless collection of data from a plurality of remote data collection units such as portable bar code readers |
5600330, | Jul 12 1994 | Ascension Technology Corporation; ROPER ASCENSION ACQUISITION, INC | Device for measuring position and orientation using non-dipole magnet IC fields |
5615229, | Jul 02 1993 | Phonic Ear, Incorporated | Short range inductively coupled communication system employing time variant modulation |
5649306, | Sep 16 1994 | Google Technology Holdings LLC | Portable radio housing incorporating diversity antenna structure |
5722050, | Apr 17 1996 | Transmitter-receiver system for use in an audio equipment | |
5771438, | May 18 1995 | FREELINC HOLDINGS, LLC | Short-range magnetic communication system |
DE29609349, | |||
DE3603098, | |||
DE9309032, | |||
EP296092, | |||
EP700184, | |||
FR2431227, | |||
FR7820886, | |||
GB1164281, | |||
GB2197160, | |||
GB2277422, | |||
WO9217991, | |||
WO9637052, |
Executed on | Assignor | Assignee | Conveyance | Frame | Reel | Doc |
Jun 14 2001 | Aura Communications Technology, Inc. | (assignment on the face of the patent) | / | |||
Jun 11 2003 | AURA COMMUNICATIONS, INC | DUCHOSSOIS TECHNOLOGY PARTNERS, LLC | SECURITY AGREEMENT | 014901 | /0235 | |
Jan 21 2004 | AURA COMMUNICATIONS, INC | DUCHOSSOIS TECHNOLOGY PARTNERS | SECURITY INTEREST SEE DOCUMENT FOR DETAILS | 014943 | /0448 | |
May 28 2004 | AURA COMMUNICATIONS, INC | AURA COMMUNICATIONS TECHNOLOGY, INC | MERGER SEE DOCUMENT FOR DETAILS | 015509 | /0498 | |
Jun 09 2004 | DUCHOSSOIS TECHNOLOGY PARTNERS LLC | AURA COMMUNICATIONS, INC | SECURITY AGREEMENT | 014709 | /0623 | |
Sep 17 2007 | AURA COMMUNICATIONS TECHNOLOGY, INC | RADEUM, INC | ASSIGNMENT OF ASSIGNORS INTEREST SEE DOCUMENT FOR DETAILS | 020166 | /0208 | |
Mar 04 2016 | RADEUM, INC | FREELINC TECHNOLOGIES INC | ASSIGNMENT OF ASSIGNORS INTEREST SEE DOCUMENT FOR DETAILS | 037935 | /0179 | |
Jul 31 2019 | FREELINC TECHNOLOGIES INC | FREELINC HOLDINGS, LLC | ASSIGNMENT OF ASSIGNORS INTEREST SEE DOCUMENT FOR DETAILS | 050164 | /0339 |
Date | Maintenance Fee Events |
Dec 10 2010 | M2553: Payment of Maintenance Fee, 12th Yr, Small Entity. |
Date | Maintenance Schedule |
Jan 01 2011 | 4 years fee payment window open |
Jul 01 2011 | 6 months grace period start (w surcharge) |
Jan 01 2012 | patent expiry (for year 4) |
Jan 01 2014 | 2 years to revive unintentionally abandoned end. (for year 4) |
Jan 01 2015 | 8 years fee payment window open |
Jul 01 2015 | 6 months grace period start (w surcharge) |
Jan 01 2016 | patent expiry (for year 8) |
Jan 01 2018 | 2 years to revive unintentionally abandoned end. (for year 8) |
Jan 01 2019 | 12 years fee payment window open |
Jul 01 2019 | 6 months grace period start (w surcharge) |
Jan 01 2020 | patent expiry (for year 12) |
Jan 01 2022 | 2 years to revive unintentionally abandoned end. (for year 12) |