Patent Application
20050048988
This invention relates to locating a telecommunication terminal that has placed an emergency call.
Within the prior art, a problem exists in attempting to identify a portable telecommunication terminal that has placed an emergency telephone call. It is necessary to locate the portable telecommunication terminal so that assistance can be rendered to the user of the portable telecommunication terminal. Portable telecommunication terminals may be a cellular telephone, an in-building wireless telephone, an IP telephone, etc.
In the absence of obstructions, it is known within the prior art to utilize global positioning satellite (GPS) devices to determine the position of the portable telecommunication device and to convey this information to the emergency center. In addition, it is known within cellular telephone systems to utilize triangulation to locate portable telecommunication units.
Whereas the prior art techniques work reasonably well where there are no obstructions, GPS devices do not function well within buildings that utilize reinforced steel floors or roofs. In addition, the utilization of GPS devices adds a considerable amount of money to the cost of a portable telecommunication device.
Also, the technique of locating a portable telecommunication unit using triangulation suffers from the problem of reflective signals if there are buildings or other objects which can reflect the radio waves. In addition, in a multi-story building where the wireless base stations are located on floors, it is possible for a base station many floors removed to actually be picking up a signal from a wireless handset.
An apparatus and method locating a portable telecommunication terminal for an emergency telephone call to a public safety answering point by detecting the emergency telephone call, communicating the emergency telephone call to the public safety answering point, and enabling a transmission device in the portable telecommunication terminal so that the portable telecommunication terminal maybe located by personnel that are dispatched by the public safety answering point using a transceiver to locate the transmission device.
To understand the operations of the embodiment illustrated in
Assuming, for the sake of example, that wireless handset 108 is within a building or among buildings where there is a large reflection of radio frequencies used by the wireless handsets. In which case, the radio signals utilized by wireless handset 108 to place the emergency call may not be utilized to pinpoint the location of wireless handset 108. However, the general location of wireless handset 108 is known by the fact that it is utilizing one of the base stations 101-103. The emergency center 113 dispatches an emergency crew which posesses emergency receiver 112. Emergency receiver 112 utilizes the signal being transmitted from the emergency transmission device of wireless handset 108 to locate wireless handset 108. In one embodiment, the frequencies generated by the emergency transmission device are lower in frequency than that utilized for the voice transmission by wireless handset 108. These lower radio frequencies are less susceptible to reflection. Hence, emergency receiver 112 can utilize directional capabilities to locate wireless handset 108.
Transceiver 206 comprises both a RF transmitter and a RF receiver. Transceiver 206 demodulates voice signals transmitted by a base station and couples these signals via the D/A section of converter 204 and hybrid 210 to loud speaker 212. Transceiver 206 receives its input analog speech signals from microphone 211. These analog speech signals are coupled to the transceiver via hybrid 210 and the A/D section of converter 204. Converter 204 converts the analog signals to digital signals which are then transmitted to RF transceiver 206. Conventional amplifiers 213 and 214 are employed for amplifying the analog speech signals obtained from microphone 211 and provided to loud speaker 212. Control messages are transferred via time domain duplexer 203 to control unit 201. In accordance with various embodiments, control unit 201 actuates and controls transmitter 219 which transmits the emergency signal via antenna 218.
IP softphone 400 is responsive to audio information received from audio receiver 401 to convert this information to digital information via sound card 403. CPU and memory 408 then transmits the audio information to enterprise communication switching system 411 via IP interface 406. When audio information is received from enterprise communication switching system 411, via WAN 409 and IP interface 406, CPU and memory 408 utilize sound card 403 to convert this information to audio information which can be presented to the user via audio transmitter 402. CPU and memory 408 perform all of the control functions of IP softphone 400. When CPU and memory 408 determine that the user is placing an emergency call, CPU and memory 408 perform the operations illustrated in the embodiments of
IP telephone 412 is similar in construction to IP softphone 400 with the exception that IP softphone 400 utilizes computer 404 to provide the conductivity to WAN 409. IP telephone 412 would simply consist of a processor, IP interface, audio conversion circuits, and an emergency transmission device, with of course the necessary microphone and speaker such as audio receiver 401 and audio transmitter 402.
One skilled in the art would readily realize that enterprise communication switching system 411 could be replaced by a telecommunication gatekeeper which would provide the necessary control functions for IP softphone 400 and IP telephone 412.
After being started in block 500, decision block 501 determines if there is a call origination. If the answer is no, block 503 performs normal processing before returning control back to decision block 501. If the answer in decision block 501 is yes, decision block 502 determines if an emergency call is being placed. If the answer is no, decision block 505 performs normal processing before returning control back to decision block 501. If the answer in decision block 502 is yes, block 504 sets up a call to the emergency center.
Decision block 506 then determines if information has been received from the emergency center. In this context, decision block 506 is determining whether control information to control the emergency transmission device has been received. If the answer is no in decision block 506, decision block 507 determines if a predefined time period has elapsed since the placing of the call to the emergency center. If the answer is no, control is returned back to decision block 506. If the answer in decision block 507 is yes, block 508 activates the emergency transmission device and transfers control back to decision block 501. In another embodiment of the invention, block 508 returns control back to decision block 506 so that the emergency center can at a later point in time adjust the frequency and power.
Returning to decision block 506, if the answer is yes in decision block 506, decision block 509 determines if control information has been received from the emergency center to control the frequency of the emergency transmission device. If the answer is yes, block 511 adjusts and activates the emergency transmission device before returning control back to decision block 501. Note, if the emergency transmission device had already been activated, block 511 merely adjusts the frequency. In another embodiment, block 511 does not return control back to decision block 501 but rather returns control back to decision block 506 so that the emergency center can make further adjustments. If the answer is no in decision block 509, it is assumed that the emergency center is adjusting the power and control is transferred to block 512 to perform power adjustment on the transmission device before returning control back to decision block 501. In another embodiment, block 512 does not return control back to decision block 501 but transfers control back to decision block 506.
Audio and control information is received from enterprise communication switching system 611 via network interface 606. Processor 603 performs all of the control functions of portable telecommunication terminal 600. When processor 603 determines that the user is placing an emergency call, processor 603 performs the operations illustrated in the embodiments of
When the operations of devices 201, 408, or 603 are implemented in software, as is shown in
In an alternative embodiment, where devices 201, 408, or 603 are implemented in hardware, devices 201, 408, or 603 can be implemented with any or a combination of the following technologies, which are each well known in the art: a discrete logic circuit(s) having logic gates for implementing logic functions upon data signals, an application specific integrated circuit (ASIC) having appropriate combinational logic gates, a programmable gate array(s) (PGA), a field programmable gate array (FPGA), etc.
Of course, various changes and modification to the illustrated embodiments described above will be apparent to those skilled in the art. Such changes and modifications can be made without departing from the spirit and scope of the invention and without diminishing its intended advantages. It is therefore intended that such changes and modifications be covered by the following claims except insofar as limited by the prior art.
