Patent Document

BACKGROUND OF INVENTION 
     The present invention relates to devices used to communicate data over telephone lines, and more particularly, to handset orientation tolerant bi-directional acoustic modems. 
     Patients with specific health conditions may require constant or frequent observation by their physicians. However, confinement to a health care facility during this observation is typically not desirable for the patient. As a solution to this problem, physicians are increasingly monitoring their patients with remote devices. The physician is still able to observe and examine the biomedical data of the patient, and the patient enjoys a certain degree of freedom. 
     When the patient is remotely monitored, they typically have some type of event recorder that acquires the biomedical data of interest. At certain intervals established by the physician, the patient needs to transmit the data to a central site for analysis by a health care provider. Generally, the data is transmitted over a telephone line using a conventional acoustic modem. 
     Conventional acoustic modems typically rely on one way communication from the event recorder to a central site where the data can be reviewed by the health care provider. For operation, the patient must dial the phone, communicate over the phone with a receiving authority at the central site to determine when transmission can begin, align the microphone of the telephone handset with the speaker of the acoustic modem, trigger the transmission, determine when the transmission is complete, and determine whether transmission of the data needs to be repeated. Many of the patients that are remotely monitored are elderly, sick, feeble, intimidated or confused by the monitoring procedures and equipment, or not highly motivated to operate the transmission of the biomedical data to the central site. Additionally, the patients may be agitated because they have just experienced some type of medical symptom. Thus, it would be advantageous to provide a device that simplifies the process of transmission of biomedical data to the central site for the patient. 
     When the patient transmits the data using a conventional acoustic modem, it is important to align the speaker or transmitter box of the event recorder with the microphone on the handset of the telephone. The transmitter box of the event recorder includes an acoustic coupler or modem on its top surface. The handset of the phone through which the data is being transmitted to a receiving station at the central site (e.g., hospital or physician&#39;s office) is placed within acoustic range of, or adjacent to, the transmitter box. A misconfiguration of the handset and transmitter box may corrupt the communication of data and render the data received at the central site useless. When a sampling of data takes several minutes to acquire and transmit, this can be a frustrating experience for both the patient and the receiving authority. In such a case, the patient must make and transmit the reading over again. Thus, it would be advantageous to provide a device that minimizes errors and saves time by simplifying the process of aligning the telephone handset with the transmitter box, and by automatically causing the data that is being transmitted to be retransmitted if the transmission was corrupted. 
     SUMMARY OF INVENTION 
     Accordingly, the invention provides a handset orientation tolerant bi-directional acoustic modem. The acoustic modem includes two transducers (a first transducer and a second transducer) and a programmable controller. Each transducer is capable of functioning as both a transmitting unit to emit acoustic signals, and as a receiving unit to receive communication from the central site. After a telephone handset is aligned with the acoustic modem, the controller determines the orientation of the telephone with respect to the two transducers of the acoustic modem. Based on the determination of the orientation, the controller selectively assigns functionality to each of the two transducers. One of the two transducers acts as the receiving unit and the other of the two transducers acts as the transmitting unit. The acoustic modem is coupled to a data source such as an event recorder, and to a converter. The data source acquires biomedical data and the converter receives, amplifies, conditions, and encodes the biomedical data for emission as an acoustic signal by the transmitting unit of the acoustic modem. The acoustic modem may also be coupled to a memory unit that is utilized to store data before transmission to the central site. 
     For operation, the patient only needs to align the microphone and the speaker of the telephone handset with the two transducers of the acoustic modem. The microphone and the speaker can be aligned with the two transducers in either orientation (i.e., the speaker on the first transducer and the microphone on the second transducer, or the microphone on the first transducer and the speaker on the second transducer). The controller determines which of the two transducers is aligned with the speaker of the handset by sampling both transducers for a detectable dial tone or other tone of the telephone. When a dial tone is properly detected in one of the two transducers, that transducer is assigned the functionality of the receiving unit to receive communication from the central site. The other of the two transducers is then assigned the functionality of the transmitting unit to emit the acoustic signals. After the functionality of each transducer is assigned, the central site is automatically dialed by emitting dialing tones with the transmitting unit. The receiving unit waits for a response from the receiving station of the central site. Once the response is received, the transmission protocol may proceed. After the transmission protocol is completed, the patient completes the process by hanging up the phone. 
     The transmission protocol of the invention includes a bi-directional transmission of data. The communication of data between the remote location and the central site can be either half duplex or full duplex. In one embodiment, the data is transmitted from the remote location to the central site in small packets of data with sequence numbers. The receiving station acknowledges whether or not the transmission of a small packet of data was proper. This acknowledgement is received by the receiving unit of the acoustic modem. If a negative acknowledgement, or no acknowledgement, is received by the receiving unit, the small packet of data is retransmitted to ensure complete transmission of uncorrupted data. The receiving station is able to organize the small packets of data in proper sequence by sequentially organizing the sequence numbers that are attached to the small packets of data. 
     These features as well as other advantages of the invention will become apparent upon consideration of the following detailed description and accompanying drawings of the embodiments of the invention described below. 
    
    
     BRIEF DESCRIPTION OF DRAWINGS 
     FIG. 1 is a schematic diagram representing a remote monitoring system according to one embodiment of the invention. 
     FIG. 2 is a schematic diagram representing a handset orientation tolerant bi-directional acoustic modem according to one embodiment of the invention. 
     FIG. 3 is a flow chart representing the functionality of the software of the programmable controller. 
    
    
     DETAILED DESCRIPTION 
     Before one embodiment of the invention is explained in full detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of components set forth in the following description or illustrated in the following drawings. The invention is capable of other embodiments and of being practiced or of being carried out in various ways. Also, it is to be understood that the phraseology and terminology used herein is for the purpose of description and should not be regarded as limiting. The use of including and comprising and variations thereof herein is meant to encompass the items listed thereafter and equivalents thereof as well as additional items. 
     FIG. 1 schematically illustrates a remote monitoring system  5  according to one embodiment of the invention. The remote monitoring system  5  includes a handset orientation tolerant bi-directional acoustic modem  10  for communicating data over a telephone line  12 . The acoustic modem  10  is located at a remote location  14  from a central site  16 . The central site  16  typically is a hospital or physician&#39;s office. The telephone line  12  has a first end  18  and a second end  20 . The first end  18  is located at the remote location  14  and the second end  20  is located at the central site  16 . The first end  18  is coupled to a telephone  22  having a microphone  24  and a speaker  26 . The second end  20  is coupled to a receiving station  32  at the central site  16 . The acoustic modem  10  includes a first transducer  28  and a second transducer  30 . In one embodiment, the first transducer  28  and the second transducer  30  are piezo transducers. As shown in FIG. 1, the acoustic modem  10  may be coupled to a data source  34 , a converter  36 , or a memory  38  or any combination thereof. The data source  34 , the converter  36 , the memory  38 , and the acoustic modem  10  may also be integral with each other in any combination, and thus, packaged as at least one combined unit, or alternatively, packaged as single units. 
     The data source  34  can be any event recorder or device that is adapted to acquire biomedical or other data including electrocardiograms, pacemaker readings, respiratory rate, heart rate, impedance measurements for determining tidal volume and minute ventilation, EEG, defibrillator data, data from event recorders and loop recorders, as well as other medical equipment such as IV infusion pumps and more. Furthermore, the data may include any signal, analog or digital, that is convertible to an acoustic signal for transmission from a remote location to a receiving station. 
     In one embodiment, the acoustic modem  10  of the invention is digital. In another embodiment, the acoustic modem  10  of the invention is analog. The analog acoustic modem may utilize a standard for frequency modulated (FM) analog transmissions, or any other analog standard. Moreover, in some embodiments, the acoustic modem  10  is suited to effect transmission of data through the traditional public-switched telephone network (PSTN), while in other embodiments (not shown), the acoustic modem  10  is adapted to communicate using an internet protocol telephone such as is commonly available from Cisco Systems, Inc. The transmission standard utilized to transfer the data from the remote location  14  to the central site  16  can include any future types of transmission. 
     The converter  36  receives, amplifies, conditions, and encodes the biomedical or other data from the data source  34  or the memory  38 . The design and signal processing utilized by the converter  36  is conventional. Any conversion methodology or techniques now known or later devised may be employed or substituted. The converter  36  does not need to be utilized if the data provided by the data source  34  or the memory  38  is already in a proper format for input to the acoustic modem  10 . 
     The memory  38  can be any conventional type of electronic storage. In one embodiment, the biomedical data is stored after acquisition by the data source  34  and before conversion by the converter  36 . In another embodiment, the converted data is stored after conversion by the converter  36  and before input to the acoustic modem. In another embodiment, the biomedical data is not stored in the memory  38 . 
     The acoustic modem  10  is further schematically illustrated in FIG.  2 . The acoustic modem  10  includes a programmable controller  40 . The first transducer  28  and the second transducer  30  are selectively coupled in alternation to the controller  40  by a drive selector  42  and an input selector  44 . The drive selector  42  actuates a switch S 1  that electrically connects one of the first transducer  28  and the second transducer  30  to the digital output  46  of the controller  40 . The signals output from the digital output  46  are sent through a digital-to-analog converter  48  and a drive signal conditioning unit  50  to the one of the first transducer  28  and the second transducer  30  that is electrically connected to the digital output  46 . The input selector  44  actuates a switch S 2  that electrically connects the other of the first transducer  28  and the second transducer  30  to the digital input  52  of the controller  40 . The signals input to the other of the first transducer  28  and the second transducer  30  are sent through an input signal conditioning unit  54  and an analog-to-digital converter  56  to the digital input  52 . 
     In operation, each transducer of the acoustic modem  10  is capable of functioning as both a transmitting unit to emit acoustic signals, and as a receiving unit to receive communication from the central site. After the patient, or someone else acting on their behalf (e.g. the patient may have just experienced a heart condition and is therefore unable to align the phone on their own), aligns the telephone handset  22  with the acoustic modem  10 , the controller  40  determines the orientation of the telephone  22  with respect to the first transducer  28  and second transducer  30  of the acoustic modem  10 . 
     The software used by the controller  40  to establish the handset orientation is illustrated in the flow chart of FIG.  3 . The software determines the orientation of the microphone  24  and the speaker  26  of the telephone  22  with respect to the first transducer  28  and the second transducer  30  of the acoustic modem  10 , and accordingly assigns functionality to the first transducer  28  and the second transducer  30 . The patient starts the software as shown at step  100 . The software can be setup to continuously sample for a detectable dial tone, or setup to only sample for a detectable dial tone when the patient triggers the controller  40  by actuating a switch  60  on the acoustic modem  10 . The software preferably continuously samples for a detectable dial tone and is therefore sampling whenever the acoustic modem  10  is turned on. 
     As shown at step  110 , the software selects the first transducer as an input, i.e. the software assigns the first transducer  28  the functionality of the receiving unit. In order to assign functionality of the receiving unit to the first transducer  28 , the input selector  44  actuates switch S 2  to electrically couple the first transducer  28  to the digital input  52 . As shown at step  120 , the software directs the first transducer  28  to “listen” for a dial tone for a first duration. In one embodiment the first duration is one half second. The duration can be any amount of time, although it is preferable to have a duration that will quickly detect a telephone handset  22  that is properly orientated with the acoustic modem  10 . Any sound that is detected by the first transducer  28  is conditioned by the input signal conditioning unit  54  and then converted from analog to digital by the analog-to-digital converter  56  for input into the digital input  52  of the controller  40 . If the noise falls within signal characteristics of a dial tone or other tone of the telephone  22 , the controller  40  considers a dial tone to be detected. Although the signal characteristics of dial tones do vary, dial tones generally are pure tones that may include a couple of harmonics and dial tones typically are not modulated. As shown at step  130  the software records the loudness of the dial tone detected with the first transducer. The value of the loudness of the dial tone detected with the first transducer  28  is recorded in a memory unit coupled to the controller that may or may not be memory  38 . 
     As shown at step  140 , the software selects the second transducer  30  as an input, i.e., the software assigns the second transducer  30  the functionality of the receiving unit. In order to assign functionality of the receiving unit to the second transducer  30 , the input selector  44  actuates switch S 2  to uncouple the first transducer  28  from the digital input  52  and electrically couple the second transducer  30  to the digital input  52 . As shown at step  150  the software directs the transducer to “listen” for a dial tone for a second duration. In one embodiment the second duration is the same amount of time as the first duration. In other embodiments, the second duration can vary from the first duration, although it is preferable to have a duration that will allow for fast detection of a telephone handset  22  that is properly orientated with the acoustic modem  10 . Any sound that is detected by the second transducer  30  is conditioned by the input signal conditioning unit  54  and then converted from analog to digital by the analog-to-digital converter  56  for input into the digital input  52  of the controller  40 . If the noise falls within signal characteristics of a dial tone or other tone of the telephone  22 , the controller  40  considers a dial tone to be detected. As shown at step  160  the software records the loudness of the dial tone detected with the second transducer. The value of the loudness of the dial tone detected with the second transducer  30  is recorded in the memory unit coupled to the controller in which the loudness of the dial tone detected with the first transducer  28  was recorded if a dial tone was detected with the first transducer  28 . 
     As shown at step  170  the software determines whether at least one dial tone was detected. The software branches back to step  110  if no dial tone was detected, and branches to step  180  if at least one dial tone was detected. At act  180 , the software compares the value of the loudness of the dial tone detected with the first transducer  28  to the value of the loudness of the dial tone detected with the second transducer  30 , determines which of the two values is greater, and thereby determines which of the two transducers is aligned with the speaker  26  of the telephone  22 . The transducer that receives the strongest or loudest dial tone signal is assumed to be the best transducer to serve as the receiving unit for the acoustic modem  10 . A dial tone may be detected by both transducers due to the proximity of each transducer to the speaker  26  of the telephone  22 . If only one dial tone was detected, the value of loudness of the dial tone detected by the other transducer will be zero and therefore necessarily less than the value of the loudness of the dial tone detected. 
     If the first transducer  28  properly detected a louder (or the only) dial tone, the software branches from step  180  to step  190 , and selects the first transducer as the receiving unit and the second transducer as transmitting unit. The input selector  44  actuates switch S 2  to electrically couple the first transducer to the digital input  52 , thereby assigning the first transducer  28  functionality of the receiving unit. The drive selector  42  actuates switch S 1  to electrically couple the second transducer to the digital output  46 , thereby assigning the second transducer  30  functionality of the transmitting unit. 
     If the second transducer  30  properly detected a louder (or the only) dial tone, the software branches from step  180  to step  200 , and selects the second transducer as the receiving unit and the first transducer as transmitting unit. The input selector  44  actuates switch S 2  to electrically couple the second transducer  30  to the digital input  52 , thereby assigning the second transducer  30  functionality of the receiving unit. The drive selector  42  actuates switch S 1  to electrically couple the first transducer  28  to the digital output  46 , thereby assigning the first transducer  28  functionality of the transmitting unit. 
     As shown at step  210  the software transmits dialing tones with the transmitting unit to auto-dial the receiving station  32  of the central site  16 . Auto-dialing removes another step of patient intervention in the process. If a patient is unable to dial, or if the number of the receiving station  32  of the central site  16  is forgotten, the patient needs only to align the telephone  22  with the acoustic modem  10  and wait while the biomedical data is automatically transmitted. 
     As shown at step  220  the software waits until an acknowledgement from the receiving station  32  is received by the receiving unit of the acoustic modem instructing the software that the receiving station is ready to proceed with the communication of data. 
     As shown at step  230  the software proceeds with the communication of the data from the remote location  14  to the central site  16 . The remote monitoring system  5  is adapted to communicate data between the remote location  14  and the central site  16 . The communication between the remote location  14  and the central site  16  can be either half duplex or full duplex. If the communication of data is full duplex, both the remote location  14  and the central site  16  can transmit data at the same time. In order to have full duplex communication, the acoustic sounds transmitted from the remote location  14  cannot have an overlapping frequency range with the acoustic sounds transmitted from the central site  16 . If the acoustic signals that are being simultaneously transmitted do have overlapping frequency ranges, the data will be corrupted and will be unusable for purposes of monitoring the patient. If the communication of data is half duplex, only one of the remote location  14  and the central site  16  can transmit data at any one time. However, half duplex communication allows for use of the complete frequency range available to the location that is transmitting the data, and therefore, half duplex communication generally allows for higher bit rates than full duplex communication. When half duplex communication is utilized to transmit the data between the remote location  14  and the central site  16 , the data is transmitted from the remote location  14  to the receiving station  32  of the central site  16  in small packets of data with sequence numbers. The receiving station  32  acknowledges whether or not the transmission of a small packet of data was proper. This acknowledgement is received by the receiving unit of the acoustic modem  10 . If a negative acknowledgement (or no acknowledgement) is received by the receiving unit, the small packet of data is retransmitted to ensure complete transmission of uncorrupted data. The receiving station  32  is able to organize the small packets of data in proper sequence by sequentially organizing the sequence numbers that are attached to the small packets of data. In one embodiment, the transmit bit rate of the communication of data from the central site  16  to the remote location  14  is slower than the transmit bit rate of the communication of data from the remote location  14  to the central site  16 . 
     Once the communication of data is completed, the software proceeds to step  240 . If the acoustic modem  10  is set up to continuously monitor for a detectable dial tone, then the software automatically returns to step  100  and begins sampling each transducer as discussed above. If the acoustic modem  10  is set up to monitor when the switch  60  is actuated, the software shuts down and waits until it is powered up again to begin sampling for a detectable dial tone. 
     The biomedical data is converted into an acoustic signal that is emitted by the transmitting unit of the acoustic modem  10 . The transmitting unit of the acoustic modem  10  is disposed within acoustic range of, or adjacent to the microphone  24  of the telephone  22 . The acoustic signal is then transmitted from the telephone  22  over the telephone line  12  to the receiving station  32  at the central site  16 . The acoustic signal is received by the computer system at the receiving station  32  and is then translated by a converter back to the biomedical data that was acquired from the patient. 
     In the preferred embodiment, the receiving station  32  of the central site  16  communicates with the acoustic modem  10  using a computer system. This eliminates the requirement of having a receiving authority at the central site  16  to communicate with the patient and facilitate the transmission of data. Thus, the patient is able to automatically transmit biomedical data at any time during the day or night. 
     It should be apparent from the discussion above and to those of ordinary skill in the art that the exact configuration of the controller  40  could be varied. For example, many of the individual components describe above could be combined on a single integrated circuit or chip and features and components could be implemented in either hardware or software. 
     Various features and advantages of the invention are set forth in the following claims.

Technology Category: 5