`

`6,093,146
`Page 2
`
`OIBER PUBLICATIONS
`
`Marquette Medical Systems, "IMPACT.wf Paging System,"
`product information, 4 pgs., 1997, downloaded from WWW.
`on Jan. 28, 1998.
`Marquette Medical Systems, "SEER XT Ambulatory Digital
`Analysis Recorders," product information, 6 pgs., 1997,
`downloaded from WWW. on Jan. 28, 1998.
`Marquette Medical Systems, "CD Telemetry," product infor(cid:173)
`mation, 5 pgs., 1997, downloaded from WWW. on Jan. 28,
`1998.
`
`Marquette Medical Systems, "Transmitter APEX S," prod(cid:173)
`uct information, 4 pgs., 1997, downloaded from WWW. on
`Jan. 27, 1998.
`
`Marquette Medical Systems, "MARS 8000," product infor(cid:173)
`mation, 5 pgs., 1997, downloaded from WWW. on Jan. 27,
`1998.
`
`Marquette Medical System, CD Telemetry-LAN, product
`information, 2 pgs., 1997, downloaded from WWW. on Jan.
`27, 1998.
`
`Fitbit, Inc. v. Philips North America LLC
`IPR2020-00828
`
`Fitbit, Inc. Ex. 1011 Page 0002
`
`

`

`

`

`

`

`

`

`U.S. Patent
`
`Jul. 25, 2000
`
`Sheet 4 of 9
`
`6,093,146
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`Fitbit, Inc. v. Philips North America LLC
`IPR2020-00828
`
`Fitbit, Inc. Ex. 1011 Page 0006
`
`

`

`U.S. Patent
`
`Jul. 25, 2000
`
`Sheet 5 of 9
`
`6,093,146
`
`100
`
`Fig. 5
`
`Initialization
`
`102
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`••
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`station on
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`and patient
`monitor turn on
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`calls Central
`Station
`
`114
`
`116
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`/
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`Information
`sent to
`Patient Monitor
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`transmission
`commences
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`transmits user
`information
`
`r - -__ ..___..........,
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`Stations are
`Initialized
`
`Fitbit, Inc. v. Philips North America LLC
`IPR2020-00828
`
`Fitbit, Inc. Ex. 1011 Page 0007
`
`

`

`

`

`

`

`U.S. Patent
`
`Jul. 25, 2000
`
`Sheet 8 of 9
`
`6,093,146
`
`400
`
`Fig. 8
`
`(
`
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`
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`
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`in Local
`memory
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`
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`Patient Monitor to
`Central Station
`
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`Transmit
`Realtime and
`stored data
`
`412
`
`I
`
`[
`
`1
`
`I
`
`Fitbit, Inc. v. Philips North America LLC
`IPR2020-00828
`
`Fitbit, Inc. Ex. 1011 Page 0010
`
`

`

`

`

`6,093,146
`
`5
`
`1
`PHYSIOLOGICAL MONITORING
`BACKGROUND
`This invention relates to physiological monitoring of
`organisms, including human patients.
`Patients receiving health care often require physiological
`measurements to be taken over relatively long periods of
`time. These measurements can be relatively easily taken
`when a patient is localized, for example during a hospital
`stay. In those instances, the patient can be connected to 10
`physiological monitors directly coupled to central stations
`that monitor and record patient data such as heart rate,
`breathing rates, blood pressure, ECG and EEG signals, and
`blood chemistry information.
`Often patients require such physiological monitoring at 15
`home, away from a hospital setting. Holter monitoring is
`often used to perform such measurements. With Holter
`monitoring, the patient wears a portable data recorder that
`makes a tape recording of continuous physiological data
`such as from an ECG or EEG. Usually the Holter monitoring
`unit is unobtrusive enough so that the patient can perform
`usual day-to-day activities with little discomfort or encum(cid:173)
`brance. Periodically, the patient must return the unit with its
`data to the doctor or technician to download and review the
`recorded data. Sometimes the lag from data recording to data
`review can be too long in relation to the relative urgency of
`the patient's condition. Additionally, having to return the
`recorded tapes can be inconvenient when multiple record(cid:173)
`ings are necessary. Many Holter monitoring units now use
`digital storage systems such as removable flash memory 30
`cards and the like.
`Recently, real-time remote physiological monitors have
`been developed. Such real-time monitors typically include a
`portable monitoring unit worn by the patient, a base station
`that communicates with the portable unit, and a central data 35
`collection station. The portable unit performs the physi(cid:173)
`ological measurements in a manner similar to a Holter unit,
`but instead of making a self-contained recording, transmits
`the data to the base station via a wireless link ( e.g., by RF
`or IR transmission). The base station is located somewhere 40
`near the patient. As the base station receives the real-time
`data, it simultaneously retransmits it to a central station via
`a communication link, typically the public telephone system.
`This real-time form of physiological monitoring allows data
`to be sent from patient to care giver within a matter of 45
`seconds. This allows for a faster diagnosis and a quicker
`response to emergencies relative to traditional Holter moni(cid:173)
`toring.
`
`2
`configured to end the storing of the received data and to send
`to the base station the stored received data from the memory
`combined with new received data received through the data
`input, when the wireless communications link is reestab-
`lished. The stored received data can be combined with the
`new received data in an interleaved fashion. A central station
`can be coupled by a communications link to the base station,
`and the communications link can be formed over a telephone
`network.
`The base station can include a base station memory and a
`modem link, and can also include a base station controller,
`the base station controller configured to store in the base
`station memory received data from the patient monitor when
`the communications link with the central station is inter(cid:173)
`rupted. The base station controller can be further configured
`to end the storing of the received data from the patient
`monitor and to send to the central station the stored received
`data from the base station memory combined with new
`received data received through the patient monitor, when the
`communications link is reestablished. The stored received
`20 data can be combined with the new received data from the
`patient monitor in an interleaved fashion. The central station
`can organize the combined stored received data and the new
`received data into a substantially continuous, time ordered
`data record. The communications link can be interrupted
`25 when a telephone connected to the base station is used to
`make a telephone call, or receives an incoming telephone
`call. The base station controller can be further configured to
`end the storing of the received data from the patient monitor
`and to send to the central station the stored received data
`from the base station memory combined with new received
`data received through the patient monitor, when the tele(cid:173)
`phone call ends.
`In general, in another aspect, the invention features a
`method for physiological monitoring including receiving, at
`a patient monitor, data regarding a physiological condition
`of a patient, transmitting in substantially real-time the
`received data from the patient to a base station via a wireless
`communications link, and storing in memory of the patient
`monitor the received data when the wireless communica-
`tions link is interrupted.
`Advantages of the invention may include one or more of
`the following. The portable patient unit provides for local
`memory storage of physiological data whenever the com(cid:173)
`munication link between patient and base station is broken.
`The base station provides for memory storage of the data
`whenever its communication link between it and the central
`station is broken. Provision of this memory storage ensures
`that very little if any data will be lost, and allows for a patient
`to move with ease into and out of range of the base station,
`50 assured that the patient's data will remain relatively secure.
`Furthermore, whenever any of the communication links are
`restored, the invention provides for concurrent transmission
`of both stored and current data which can be spliced together
`into a seamless data stream at either the base station or the
`central station. Also, memory storage of data can automati(cid:173)
`cally begin whenever a phone coupled to the phone line used
`by the base station is used, and the data transmission can
`resume whenever such phone use ends. A patient does not
`need an extra dedicated phone line to have continual physi-
`ological monitoring, and the patient is allowed greater
`freedom of movement away from a base station without loss
`of data. Further, since the patient unit typically has non(cid:173)
`volatile memory, it can also be used as a simple Holter-type
`monitor, providing a flexible monitoring system.
`Other features and advantages of the invention will
`become apparent from the following description and from
`the claims.
`
`65
`
`SUMMARY
`In general, in one aspect, the invention features a physi(cid:173)
`ological monitoring system including a base station, the base
`station having a first wireless transceiver, and a patient
`monitor, the patient monitor comprising a data input, the
`data input configured to receive data regarding a physiologi- 55
`cal condition of a patient, the patient monitor further com(cid:173)
`prising a second wireless transceiver, the patient monitor
`capable of entering a wireless communications link with the
`base station through the first and second wireless
`transceivers, and of transmitting in substantially real-time 60
`the received data from the patient to the base station, the
`patient monitor further comprising a controller and a
`memory, the controller being configured to store the
`received data in the memory when the wireless communi(cid:173)
`cations link is interrupted.
`Embodiments of the invention may include one or more
`of the following features. The controller can be further
`
`Fitbit, Inc. v. Philips North America LLC
`IPR2020-00828
`
`Fitbit, Inc. Ex. 1011 Page 0012
`
`

`

`6,093,146
`
`3
`DRAWINGS
`
`FIG. 1 is schematic diagram of a physiological monitor-
`ing system.
`FIG. 2 is a schematic diagram of a patient monitor.
`FIG. 3 is a schematic diagram of a base station.
`FIG. 4 is a schematic diagram of a central station.
`FIG. 5 is a flow chart of an initialization of a physiological
`monitoring system.
`FIG. 6 is a flow chart of an interruption of data transmis(cid:173)
`sion by a telephone call.
`FIG. 7 is a flow chart of the resumption of data transmis(cid:173)
`sion after a telephone call.
`FIG. 8 is a flow chart of a data interruption procedure.
`FIG. 9 is a flow chart of a shut down procedure
`
`DESCRIPTION
`
`Referring to FIG. 1, a physiological monitoring system 10
`includes a patient monitor 12 worn by a patient 2 (which can
`be, for example, a human being, or an animal under veteri(cid:173)
`nary care), a base station 14, and a central station 16. Patient
`monitor 12 and base station 14 communicate via, for
`example, a wireless communication link 18, such as a radio
`frequency (RF) or infrared (IR) communication system.
`Base station 14 is coupled to an external communication
`network 20, typically a public telephone network, and to one
`or more telephones 22. Central station 16 typically includes
`a display system 24 (for example, a computer monitor),
`printing device 26, and database system 28.
`Referring to FIG. 2, patient 2 is physically coupled to
`patient monitor 12 via coupling 30. Physiological signals
`such as ECG, blood pressure, temperature, or respiration are
`filtered and amplified by an analog signal conditioning block
`32, and then converted to digital signals by an analog-to(cid:173)
`digital (ND) converter 34. The digitized data is then trans(cid:173)
`mitted by micro-controller 36 to base station 14 through RF
`transceiver 40 via wireless communication link 18. This
`constitutes a Normal Transmit Mode. When the data signals
`are not being transmitted, micro-controller 36 can store them
`in non-volatile memory 38, which can be conventional flash
`memory. Microcontroller 36 is coupled to RF transceiver 40
`via an asynchronous serial link at approximately 19.2
`Kbaud, however any number of data communication links 45
`can be used.
`Micro-controller 36 can be a Motorola MC68HC711K4
`single-chip microcomputer, operating with a bus speed of 2
`MHz. Non-volatile memory 38 can be AMD AM29F040
`512kx8 Flash memory. With an ND sampling of data of 100 50
`samples/sec, with 8 bits per sample, patient monitor 12 can
`store approximately 88 minutes of patient data. Patient
`monitor 12 can be powered by rechargeable batteries, e.g.,
`by four AA-size Lithium Metal batteries made by Tadiran
`Industries, allowing for 24 hours continuous operation.
`Signal detector 42 monitors the status of RF transceiver
`40 to detect when wireless communication link 18 becomes
`unstable or is severed, at which time signal detector 42
`indicates to micro-controller 36 to enter a Wireless Fault
`Induced Memory Mode. During this mode, caused for 60
`example when the patient monitor 12 leaves the communi(cid:173)
`cation range of base station 14, patient monitor 12 tempo(cid:173)
`rarily stops transmitting data and starts storing data sequen(cid:173)
`tially in non-volatile memory 38. During the Wireless Fault
`Induced Memory Mode, patient monitor 12 enters a low 65
`power state and periodically powers up to determine
`whether the wireless communication link 18 can be rees-
`
`4
`tablished. If link 18 is reestablished, patient monitor 12
`reenters Normal Transmit Mode and resumes transmitting
`real-time data. Concurrently, patient monitor 12 transmits
`the recorded data from non-volatile memory 38. Real-time
`5 data is transmitted in discrete bursts ( described further
`below). Between each burst of real-time data, patient moni(cid:173)
`tor 12 can transmit one or more bursts of recorded data from
`memory 38 until a new burst of real-time data is ready for
`transmission. The entire contents of local memory 38 are
`10 thereby transmitted in this interlaced manner. Both real-time
`and recorded data can then be transmitted from base station
`14 to central station 18. Since each data burst (whether
`stored or realtime) is uniquely time stamped, central station
`16 can correctly splice the recorded data stream with the
`15 real-time stream to produce a single, continuous data stream.
`Patient monitor 12 can also be configured by signals from
`the base station or central station via wireless communica(cid:173)
`tion link 18. Signal detector 42 can determine if such
`configuration information (including, for example, channel
`20 montage, where different channels are assigned to different
`data streams: e.g., channel 1 is ECGl, channel 2 is ECG2,
`channel 3 is the temperature) has been received by RF
`transceiver 40. Either signal detector 42 can then signal the
`micro controller 36 to pause data transmission and receive
`25 the incoming configuration information instead. During this
`process, outgoing data from patient 2 can be stored in
`non-volatile memory 38, or in buffer 35, and then sent when
`incoming data stops. Or, incoming data can be received
`between bursts of outgoing data, resulting in no data delays.
`30 To facilitate these data paths, RF transceiver 40 can also be
`configured for half or full duplex operation. Furthermore,
`RF transceiver 40 can have an internal memory buffer that
`can be used in tandem with other buffers 35 (located, e.g., in
`a separate RAM or in an internal buffer in microcontroller
`35 36) to store data before transmission. This data can include,
`for example, the last few seconds of transmitted data to
`ensure that data transmitted at the onset of a communication
`interruption is not lost.
`Patient monitor 12 can also include a direct connector 39
`40 for coupling patient monitor 12 to base station 14 through
`cabling instead of RF transmissions. In addition, patient
`monitor 12 can include a patient event monitor 37 explained
`further below.
`Referring to FIG. 3, base station 14 typically includes RF
`transceiver 44, signal detector 46, controller 48, modem 50,
`signal switch 52, signal detector 54 and memory 56. RF
`transceiver 44 is coupled via wireless communication link
`18 to the corresponding RF transceiver 40 in patient monitor
`12. Base station 14 when located in the vicinity of patient 2
`and patient monitor 12 typically maintains a stable RF link.
`Base station 14 can also comprise a series of RF transceivers
`(or other communication link transceivers) located, e.g.,
`through a series of rooms, so that patient monitor 12 can be
`55 in continual contact as patient 2 moves about.
`In Normal Transmit Mode, RF transceiver 44 receives
`data from patient monitor 12, and controller 48 directs the
`data through modem 50 and signal switch 52 onto telephone
`network 20 (and then on to central station 16). In Normal
`Transmit Mode, signal switch 52 is set so that modem 50 is
`coupled to, and telephone 22 is uncoupled from, public
`network 20. One embodiment transmits about 6-7 seconds
`of physiological data in a single 300 ms data burst from
`patient monitor 12 to base station 14. This helps to minimize
`power consumption, particularly at RF transceiver 40.
`Base station 14 typically expects data transmissions from
`patient monitor 12 at regular intervals ( e.g., every 6 to 7
`
`Fitbit, Inc. v. Philips North America LLC
`IPR2020-00828
`
`Fitbit, Inc. Ex. 1011 Page 0013
`
`

`

`6,093,146
`
`5
`seconds). If RF signal detection unit 46 does not detect new
`data from patient monitor 12 before a specified timeout
`occurs (e.g., 100 milliseconds after the normal 6 or 7 second
`period between bursts), or patient monitor 12 continues to
`send error-filled data bursts, base station 14 enters a Wireless 5
`Fault Induced Memory Mode and signals central station 16
`via modem 50 that this condition has occurred. In this mode,
`RF transceiver 44 continues to send a linking signal to
`central station 16 until patient monitor 12 successfully
`re-links with base station 14 and resumes data transmission. 10
`Patient monitor 12 will continue to attempt to resynchronize
`with base station 14 for typically 6 seconds every minute.
`This intermittent synchronization is used to conserve battery
`energy, since transceiver 40 of patient monitor 12 consumes
`far more energy attempting to synchronize than during 15
`normal transmission. Average synchronization requires, e.g.,
`about 4 seconds, so that allowing 6 seconds to attempt
`connection should be adequate. When base station 14 once
`again receives data from patient monitor 12 with no detect(cid:173)
`able (uncorrectable) errors, it then resumes normal transmit 20
`mode and so signals central station 16 via modem 50.
`If modem signal detection block 54 detects that the
`telephone 22 has been taken off the hook (e.g., because
`patient 2 is making a telephone call), base station 14 Enters
`Modem Fault Induced Memory Mode and so signals central 25
`station 16 via modem 50. After signaling central station 16,
`signal switch 52 disconnects modem 50 from public tele(cid:173)
`phone network 20 and connects telephone 22 so that the
`patient can complete the telephone call. During Modem
`Fault Induced Memory Mode, wireless communication link 30
`18 will be maintained so that data continues transmitting
`from patient monitor 12 to base station 14. During Modem
`Fault Induced Memory Mode, this data is rerouted to base
`station memory 56 where it is sequentially stored until the
`system returns to Normal Transmit Mode. When modem 35
`signal detection block 46 detects that patient 2 has hung up
`telephone 22, signal switch 52 reconnects modem 50 to
`public telephone network 20, and the modem link to central
`station 16 is reestablished. The system thus reenters Normal
`Transmit Mode and resumes transmitting real-time data to 40
`central station 16 while concurrently transmitting recorded
`data from base station memory 56. Again, central station 16
`can then splice the recorded data stream into the real-time
`stream to produce a single continuous uninterrupted data
`stream.
`If the patient's local telephone service includes a "call
`waiting" feature, then system 10 can also allow the patient
`to receive incoming telephone calls. If modem signal detec(cid:173)
`tion block 54 detects that there is an incoming telephone call
`from public telephone network 20, then base station 14 can 50
`enter Modem Fault Induced Memory Mode and signal
`central station 16 that this condition has occurred. Just as
`with a patient-initiated telephone call described above, sig(cid:173)
`nal switch 52 can then disconnect modem 50 from telephone
`network 20, connect telephone 22 to telephone network 20,
`and then switch the active line from the link with central
`station 16 to the incoming caller. When modem signal
`detection block 54 detects that the patient has hung up
`telephone 22, the system returns to Normal Transmit Mode
`just as in the case when the patient initiates and then
`terminates a telephone call.
`It may be that a fault in telephone network 20 itself might
`cause a communication failure with central station 16, and
`with such an occurrence, some data might be lost, since base
`station 14 will believe it was correctly sent during the early 65
`stage of disruption. To make system 10 more tolerant of this
`sort of fault, a buffer 57 formed in RAM memory 56 can
`
`6
`store the last few seconds of data sent to central station 16,
`and allow such data to be resent in the event of this sort of
`network fault. When base station 14 does not receive receipt
`confirmation from central station 16 for a particular trans(cid:173)
`mitted data block, base station 14 can resend it from its
`buffer 57.
`Referring to FIG. 4, central station 16 includes modem 58,
`computer 60, display 24, printer 26, and database 28. Central
`station 16 is typically located remote from base station 14
`and patient monitor 12-it can be in the same building, or
`many miles away. Modem 58 is coupled to public telephone
`network 20, and receives and transmits data to and from base
`station 14. As central station 16 receives data, it can be
`displayed on display 24, printed out on printer 26, stored in
`database 28, or retransmitted to a third party (such as a
`patient's physician). Multiple stored and received data
`records can be reviewed and compared. Computer 60 can
`also contain an expert system that performs real-time or
`delayed analysis of received patient data. Such a system can
`automatically generate analysis reports, or activate alarms if
`emergency conditions occur. The alarms can be audible or
`shown on display 24. The reports can also be forwarded to
`a third party, e.g., a physician. Additionally, if an emergency
`condition occurs, computer 60 can automatically send a
`message via modem 58 and telephone network 20 to, e.g., a
`pager of a clinician on call for the patient.
`Referring to FIG. 5, initialization 100 of physiological
`monitoring system 10 begins when central station 16 is
`typically left in an "on" state (step 102), ready to receive
`remote telephone calls from base stations 14. When patient
`2 is ready to have physiological data recorded and sent to
`central station 16, patient 2 typically turns on both base
`station 14 and patient monitor 12, and appropriately attaches
`any required physiological monitoring equipment from
`patient monitor 12 to his or her body (step 104). Next, base
`station 14 calls central station 16 over public telephone
`network 20 (step 106). This calling step can also be over a
`private network, for example, within a medical complex or
`hospital. Patient monitor 12 synchronizes via wireless com(cid:173)
`munication link 18 to base station 14 (step 108). Base station
`14 also transmits user information such as name, address,
`patient ID, attending physician, medical condition, and the
`like (step 110). This information can be located at either
`patient monitor 12 or base station 14.
`In one embodiment, wireless communication link 18
`employs a frequency hopping, spread spectrum RF commu(cid:173)
`nication system, using WIT2400 2.4 Ghz wireless transceiv(cid:173)
`ers from Digital Wireless Corporation. The frequency hop-
`ping scheme has desirable resistance to narrowband
`interference and fading, and also provides a measure of data
`security. Noise immunity can be particularly useful with
`regard to medical devices operating in the ISM RF bands,
`since there may be one or more relatively high-power
`55 narrowband interference sources within the field of coverage
`of patient monitor 12.
`The WIT2400 RF transceiver 40 in patient monitor 12 is
`configured as a remote unit, and when activated, attempts to
`synchronize to the frequency hopping pattern of companion
`60 RF transceiver 44 of base station 14. When the two RF
`transceivers 40 and 44 synchronize, data transmission can
`begin.
`When found by transceiver 44 of base station 14, patient
`monitor 12 transmits an initialization code to "zero out" the
`time base, and tell the system that a new data record is
`starting (step 108). This initialization sequence differentiates
`the power-up condition from a loss-of-signal condition. The
`
`45
`
`Fitbit, Inc. v. Philips North America LLC
`IPR2020-00828
`
`Fitbit, Inc. Ex. 1011 Page 0014
`
`

`

`6,093,146
`
`10
`
`7
`initialization code can be as simple as a 00:00 time stamp,
`and is, in turn, propagated to central station 16 (step 112).
`Central station 16 then transmits configuration information
`(such as channel gain and channel montage) through base
`station 14 to patient monitor 12 (step 114). System 10 is then
`ready to receive data from patient monitor 12 (step 116).
`One data gathering and transmission protocol for, e.g.,
`electrocardiogram (ECG) data, uses data sampled at 120
`samples per second. At the highest protocol level, the data is
`divided into bursts, whereby a buffer within patient monitor
`12 (which, as mentioned above, can be RAM buffer 35, or
`a buffer in RF transceiver 40 or in microcontroller 36 or
`another buffer system) stores approximately 5 seconds of
`data. When the buffer is full, its contents are transmitted to
`WIT2400 RF transceiver 40 at 19.2 kbaud via a hardwired 15
`serial port. The data is then transmitted via RF communi(cid:173)
`cations link 18 from patient monitor 12 to base station 14 at
`approximately 250 kbaud.
`The first four bytes of each burst of data is a time stamp.
`The time stamp has a 4 millisecond resolution and counts
`relative from initialization. The data with the time stamps
`are propagated to central station 16 which monitors the
`activities taking place throughout system 10.
`The data has a single byte of resolution (but can have,
`with greater data throughput, higher resolution). Data begin(cid:173)
`ning with FFh is reserved for special codes, providing a
`resolution of 255 discrete levels. When central station 16
`encounters an FFh byte ("h" for hexadecimal), it reads the
`subsequent bytes to determine the nature of the special code.
`Example codes include:
`
`8
`and if the packet contained any errors, patient monitor 12
`will retransmit.
`Referring to FIG. 6, when a telephone call interrupts (step
`200) normal data transmission between base station 14 and
`5 central station 16, base station 14 first notifies central station
`(202) of the interruption. At substantially the same time,
`base station 14 starts storing incoming data from patient
`monitor 12 in its local memory 56. If the telephone system
`provides for call waiting (step 206), then base station 14
`switches the first line (with the link to central station 16) to
`be the waiting line (step 208). If there is not call waiting, the
`link to central station 16 is simply cut (step 210). Either way,
`the data path is disconnected to the phone line by signal
`switch 52 (step 212) and telephone 22 is instead connected
`to telephone network 20 (step 214).
`Referring to FIG. 7, at the end of a telephone call (step
`300), telephone 22 is disconnected from telephone network
`20 by signal switch 52 (step 302). Then the data path (via
`modem 50) is reconnected to telephone network 20 (step
`304). If the system has call waiting (step 306), then the
`20 waiting line attached to central station 16 is reestablished as
`the active line (step 308). If there is not call waiting, central
`station 16 is redialed and the link between base station 14
`and central station 16 reestablished (step 310). Either way,
`base station 14 then begins to transmit both real-time data
`25 and stored data to central station 16 (step 312).
`Referring to FIG. 8, regardless of whether a data inter(cid:173)
`ruption (step 400) occurs between patient monitor 12 and
`base station 14 (e.g., due to the patient leaving the reception
`area of base station 14), or between base station 14 and
`30 central station 16 ( e.g., from line noise or other phone
`network interruptions), received data is stored locally up to
`the point of interruption (step 402). That is, if the interrup(cid:173)
`tion is between patient monitor 12 and base station 14, data
`is stored in the memory of patient monitor 12, and if the
`35 interruption is between base station 14 and central station
`16, data is stored in the memory of base station 14. The
`system then waits for full data reconnection between patient
`monitor 12 and central station 16 (step 404). Once recon(cid:173)
`nection is performed, the system establishes the data links
`40 between patient monitor 12 and central station 16 (step 408).
`Once the data link is established, base station 14 transmits
`both real-time data and stored data to central station 16 (step
`412).
`Referring to FIG. 9, when the system is to be shutdown
`45 (step 500), base station 14 sends the last data packet (step
`502). Then base station 14 signals central station 16 that a
`shutdown is imminent (step 504) with a shutdown code ( e.g.,
`FFFFh), and disconnects data links to patient monitor 12 and
`central station 16 (step 508). At this point, the system
`50 including patient monitor 12 and base station 14 shuts down
`(step 510).
`Other embodiments are within the scope of the claims.
`For example, a number of other forms of communications
`links between patient monitor and base station can be
`55 established, for example, through infrared communication
`links and other RF transceivers and protocols. The commu(cid:173)
`nication link between base station and central station can be
`through any number of communications channels, including
`private branch exchanges and local area networks. A variety
`of physiological data can be measured, stored, and sent by
`the patient monitor.
`What is claimed is:
`1. A physiological monitoring system comprising:
`a base station, the base station having a first wireless
`transceiver; and
`a patient monitor, the patient monitor comprising a data
`input, the data input configured to receive data regard-
`
`FFOOh
`FF55h
`FFAAxxh [00-FEh]
`FFFFh
`
`End of Burst
`Patient Event Button
`Battery level
`End of transmission
`
`Each data burst will always be terminated by "FFOOh". A
`patient event button 37 can be located on patient monitor 12
`and pushed by the patient 2 at any time during the
`transmission, to tag a particular string of data as occurring
`at some point in time pertinent to patient 2 ( e.g., during
`angina or racing heart beat, or to mark an exercise period or
`other activity). A visual and audible alert can be activated at
`base station 14 when patient event button 37 is depressed.
`The battery level of patient monitor 12 can be transmitted to
`central station 16 on a regular schedule or in response to
`polling by central station 16. When patient monitor is
`powered down, it sends the "end of transmission" code.
`All downstream communications (such as those from
`central station 16 to base station 14 or patient monitor 12)
`occur between data bursts. Such communications can
`include sending configuration information and polling
`patient monitor 12 for its battery level.
`At a lower protocol level, the communication between
`WIT2400 transceivers is in a packetized data format of
`between O and 255 bytes. The format has a start character
`(such as 02h), followed by a remote address comprising a
`unique byte-long address of the patient monitor. This allows 60
`several patient monitors 12 to be used simultaneously with
`one base station 14. Remote address is followed by a leng