CA1137239A - Telecommunications system incorporating portable communications units - Google Patents
Telecommunications system incorporating portable communications unitsInfo
- Publication number
- CA1137239A CA1137239A CA000340664A CA340664A CA1137239A CA 1137239 A CA1137239 A CA 1137239A CA 000340664 A CA000340664 A CA 000340664A CA 340664 A CA340664 A CA 340664A CA 1137239 A CA1137239 A CA 1137239A
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- Prior art keywords
- communication
- portable
- portable communication
- communication unit
- telecommunication
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Abstract
A B S T R A C T
TELECOMMUNICATIONS SYSTEM INCORPORATING
PORTABLE COMMUNICATIONS UNITS
The invention relates to the incorporation of an alternative to the public telephone kiosk or payphone in a telecommunication system. It provides a telecommunication system having communica-tion terminals connected to it, and portable communication units for the users. Each communication unit includes a transmitter and receiver enabling coupling to any of the communication terminals over a short range together with a credit meter adapted to co-operate with the communication terminal and to have its credit level adjusted by the telecommunications system's call-charge metering arrangements. By such an arrangement individual users have and carry with them their own portable telephone units which are of similar size to a pocket calculator. In order to make a call the user positions himself within some standard range (e.g. 5 meters) of any one of the communication terminals and then operates his communication unit to gain access to the telecommunications system by way of the communication terminal.
The portable communication unit comprises a push-button dialler, a liquid crystal display and integral earpiece and microphone extendable to the normal spacing from the earpiece using an acoustic tube. Access to the telephone system is gained by performing an interactive key code sequence using the communications unit. When access is confirmed by the communication terminal the user keys in the required telephone number and when the call is established the terminal indicates call cost information over the reverse speech link. The unit includes a PROM as a credit meter and the cost information cancels the requisite credit from the memory.
TELECOMMUNICATIONS SYSTEM INCORPORATING
PORTABLE COMMUNICATIONS UNITS
The invention relates to the incorporation of an alternative to the public telephone kiosk or payphone in a telecommunication system. It provides a telecommunication system having communica-tion terminals connected to it, and portable communication units for the users. Each communication unit includes a transmitter and receiver enabling coupling to any of the communication terminals over a short range together with a credit meter adapted to co-operate with the communication terminal and to have its credit level adjusted by the telecommunications system's call-charge metering arrangements. By such an arrangement individual users have and carry with them their own portable telephone units which are of similar size to a pocket calculator. In order to make a call the user positions himself within some standard range (e.g. 5 meters) of any one of the communication terminals and then operates his communication unit to gain access to the telecommunications system by way of the communication terminal.
The portable communication unit comprises a push-button dialler, a liquid crystal display and integral earpiece and microphone extendable to the normal spacing from the earpiece using an acoustic tube. Access to the telephone system is gained by performing an interactive key code sequence using the communications unit. When access is confirmed by the communication terminal the user keys in the required telephone number and when the call is established the terminal indicates call cost information over the reverse speech link. The unit includes a PROM as a credit meter and the cost information cancels the requisite credit from the memory.
Description
~3723~
~I~'LE: ~LECOMMUNICA~ION SYS~M I~CORPORA~ING
POR~ABIE COMMU~ICA~IO~ UNI~S
~ `he present invention relates to telecommunications systems and is more particularly concerned with.improving the facilities currentl~ provided by public call-office kiosks and the like.
During recent years the telepho~e system has been expanded to allow data communication to be added to speech communication between subscribers. ~uch data com~unication facilities, however, have had limited penetration, as far as the total subscriber's on a national telephone network is concerned, mai~l~ because relatively expensive modem and hard copy printer and ke~board communication equipment is required at each end o~ a communication connection. In the main people are, however, periphatetic and it is necessar~ for communication system~ to recognise that subscribers require to make telecommunicatio~ caIls as they move around from their natural ba~e, for example as they travel from home to office, travel away on business or on holidayO At present7 however, onl~ a few people with radio-telephone equipment can actually take their communication equipment with them. ~or the remainder public call offices and renters pa~-phones must suffice.
According to the invention there is provided a telecommunication s~stem ha~ing a pluralit~ of communication terminals connected to the switching network of the system, each communication te~minal being arranged to co~operate with a pluralit~ of portable communication units each of .
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_ ~ _ which is adapted to co-operate with a~ of the communication terminals to set-up telecommunication càlls involving the network to netwoxk terminations and each portable communication unit includes a call tariff charging arrangement adapted to be used to account for the usage of the portable communication unit o~ chargeable telecommunication calls involving the network.
~ he present in~ention envisages a telecommunication system ha~ing a pluralit~ of subscribers terminals and a 10. pluralit~ of communication terminals connècted to the networ~ of the s~stem, each communication terminal is arranged to co-operate with a pluralit~ of portable commu~ication units a~d each portable communication unit ` i9 adapted to co-operate with any of said communication terminals to set-up telecommu~ication calls i~volving the . network and a portable communication unit to a~y of the subscribers terminals on the network and each portable communication u~it includes means for coupling the portable communication unit to a communication te~minal, means for txansmitting telecommunication network control information and communication informatio~ to a commu~ication te~minal, mea~s for receiving telecommunication information from a commllnication terminal and telecommunication tariff credit metering arrangements adapted to decrease the telecommunica-tion call charge credit of the handset in accordance withthe telecommunication call usage of the handset and each communication terminal includes means for inter~acing the portable communication units with the telecommunications ., . , :, . , , :. , .~ , ,: . ~
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network including mea~s for receiving telecommlln;cation in~ormation from a portable communication unit and means ~or transmitting telecommunications information to a portable communication unit.
In one embodiment of the invention the co~munication terminal unit includes means for computing tarif~ credit metering adaustment information from the network tariff metering informatio~ and means for communicating the adjustment information to the portable communications unit to modify the contents o~ the credit metering arrangement.
In a simple interpretation of the invention individual users of the arrangement are provided with portable telephone units which are physically similar to a pocket calculator and include a telephone transm~tter, receiver, key pad unit and call credit store. ~he portable communica-tion unit is arranged to co-operate with the communication terminal, coupling between being by radio, inductive loop, optical radiation, ultrasonic coupling, hard wire ccupling or the like~
I~ order to make a telecommunications call, the user positions himsel~ within some standard distance, say five meters, of one of the communication termi~al and then op~rates his portable communication llnit to gain access to the telephone system to make a telephone call. ~he communication terminal ma~ be mounted at any convenient position whether on a post, wall or roof for example.
~he communications terminal need be o~ small size and is arranged to operate unattended. It ma~ be hidden behind a ...... .-~37239 facade say three meters above ground level and marked with a logo such as "phone point". Accordi~gl~ the communications terminal occupies little or no space, as compared with the conventional kiosk and is not accessible to vandals. ~he portable telephone unit comprises a push-button key pad for dialling, a displa~ device and an integral earpiece together with a microphone which for example is extendable to the normal spacing from the earpiece using an acoustic tube. ~ccess to the telephone s~stem is gained by touching a key code sequence on the poxtable telephone unit, when the user is within range of the terminal unit. When access is confirmed, the user keys in the standard area code plus the required telephone number and when the call is established the communication terminal indicates cost information over the reverse communication link to the portable telephone unit~ ~he credit meter arrangement is amended by this i~formation.
In more extensive interpretations a poxtable commu~ications unit ma~ be arranged to incorporate the equipment nece~sary for the setting-up of data communication connections with the portable communication u~it including a data modem, hard copy pri~ter and keyboard in addition to the call tariff metering arrangementr In such circumstances the communication terminal will act as a normal telecommunica-tions connection interfacing the portable communication unitto the telephone network. Alternatively the communication terminal may be provided with the modem facility and the portable communication unit with the printer and keyboard . .
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facilit~ only in addition to its call tariff metering arrangement and normal telephone connection ~acilities.
Each communication terminal is arranged to provide telecommu~icatio~ facilibies for a number of portable communication units allowing simultaneous commlln;cation calls to be in being at the same timeO Combinations of differing types of telecommunicatio~s calls involving voice communication and or data communication will be handled by the communication terminal. ~he communication terminal 10 - unit is arranged to handle for example eight communication chPnnels and is provided with one common control chPnnel.
~he common control channel is used to set-up the initial connection between a "calling" handset and the termi~al u~it which, upon vaIidation of the interchauge between the handset and terminal unit, allocates one of the communica-tion ch~nnels which is used thereafter for telecommuLication signalling and communication purposes for the duration of the call~
~n addition the communications terminal ma~ also be provided with so-called "teletext" or "view data" facilities allowing a subscriber with a portable communications unit incorporating the necessary interrogation facilities to ~se~
communication with the Pr~~,-Or~CT~ a~d CEE~A~ systems as required.
~urther the communication ter~inal may be provided with store and forward facilities allowing messages to be stored for passage to a busy subscribers terminal at a later date. ~picall~ store and forward messages could be held ,:; . ,:. .- .:: , , . ,:, .,, . .: .
:, ~ ~3~Z39 _ in the communication terminal for transmission outside the busy periods of commuDication activity allowing the recorded message to be sent at the low tariff rate after having being recorded during a higher tariff rate period~
Under such circumstances the communication terminal will compute the lower tariff and arrange for the credit store arrangement in the portable communication unit u~ed in making the recorded message to be adjusted accordingly.
~ypically the credit store arrangement comprises a programmable read only memory and tariff information I communicated from the communication terminal is used to ! erase the credit progressively from the memory~
I ~he portable communication unit is arranged to include a display device, typicall~ of the liquid crystal type, t 15 which may be used to indicate the cost of an individual telecommunication call and the amount of credit left in the portable communication unit. In addition the displa~
may be used to in~icate the telephone nùmber dialled to validate the integxity of the reverse link betwee~ the i 20 portable communication unit and the commu~ication te~minal.
~he invention, together with its various features will be more readily understood ~rom the following description which should be read in conjunction with the aCcQmpa~ying drawings. Of the drawings:-Fig. 1 shows in block diagram form, the equipment necessary ~or the handset or portable communication unit, Fig. 2 shows in block diagram form, the equipment necessary fox the "phone point" terminal or communication .
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terminal, ~ ig. 3 shows the radio frequency stability control section of the portable commum cation unit, ~ ~igo 4 shows a flow diagram of the operations performed b~ the h~ndset in the execution of a call whereas Fig. 5 shows a flow diagram of the operations performed b~ the phone poin-t terminal in the handling of a call.
In the following description the handset refers to the portable communicatio~ unit whereas the phone point terminal refers to the communication terminal.
Before embarking upon a detailed discussion of the e~uipment used in the handset and communication te~minal unit of the invention con~ideration will be given to the overall new telecommunication s~stem ~acilities which may be provided by the e~uipment of the invention. Hereafter -the new s~stem will be referred to as phone point. ~he two maaor elements of the phone point s~stem are (i) a portable teIecommunications handset incorporating a micro-processor which controls the handling o~ telecommu~ication calls a~d the accountancy for those calls and-~ii) a communication -terminal also micro-processor controlled and arranged to handle a number of handset calls at any one time and to interface the handsets into the normal telecommunication network conmunicating call accountancy information to the handset communication with the terminal. ~gpically the handset comprises a minature push-button telepho~e instrument of the size of a pocket calculator which includes a display device, a micro~processor, a credit store memo~, a -- - -1~37;~;~9 telecommunication transmitter and receiver and equipment for co~municating with the terminal unit. ~he handset when not in operation ma~ be folded up so that it ma~ be carried in a suit pocket or handbag. When it is required to use the handset it is opened up so that it forms a telephone instrument handset. ~he terminal unit of the phone point system is used to interface the handsets to the normal telecommunication network.
~ypically the phone point terminal ~lnits are provided in public places such as airport terminals, railway stations, theatre foyers1 shopping precincts and the like in a similar manner to present day telephone kiosks. ~owever the phone point terminal unit is not equipped with a telephone instrument handset or coin collecting equipment.
Subscribers to the phone point system are allocated their own portable handsets which in the simplest interpretation of the phone point system include a telephone call credit store. A subscriber wishing to make a phone point call simply positions himself within a short distance~ say 5 meters, of a phone point terminal unlt and uses his handset to set-up a telephone call by way of the phone point te~minal unit.
Commu~ication between the handsets and each phone point terminal unit involves radio com~unication involving microwave communication links. ~ach phone point terminal is provided with one common control chAnnel and eight communication channels. lhe common control ch~nnel is used during initial set-up between a handset and a phone :: --~37~;~9 point terminal unit before an available communication cha~nel is allocated ~or use on a telephone call. During a telephone call the call credit memory in the handset is adjusted i~ accordance with the cost of the ~elephone call made. At the end of the call the subscriber may control the handset micro-processor to operate the handset display to indicate the total cost of the completed call and the remaining credit in the credit memory.
~ach phone point terminal unit is arranged to handle concurrentl~ a number of phone point calls and the terminal unit incorporates equipment for interfacing the so calls to the telephone network.
~ rom the above it can be see~ that the pho~e point system is analogous to present day telephone kiosk systems but with the particular added advantages of enhancing service availability, using the network more efficiently and providing isolated call accountancy management. The service availability is enhanced because the intrinsic total terminal capital cost is lower since each terminal can be used by a number of subscribers simultaneousl~.
~etwork utilisation is increased because of the ease of use of the terminals-and concentration o~ facilities and because of the simpli~ied credit/cash management system.
~he use o~ a credit memory in each handset which retains either the level of credit purchased in advance by the subscriber or by direct debiting by a central charging system improves the telecommunications administrations cash flow and removes the security hazard presented by cash-. : , . ..
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~37~39 boxes in telephone kiosks.
Consideration will now be given to the equipment used in a handset and a commlLnication terminal unit in the phone point s~stem.
~he handset equipment is ~hown in ~ig. 1 and consists of a liquid cr~stal displa~ device HICD, a push button ke~board HE, a micro~processor based operation control system ~M-C, a call credit store ECS, a telephone instrument transmitter H~ and receiver ~R and a low power crystal controlled radio link HRE~/K~ which handles di~ital information derived from speech using pulse code modulation techni~ues involving the codec ~C and~the digital tra~smitter-receiver H 9~-R.
~ ~ is operated under micro-processor control to display the following information:- telephone ~umber dialled, stored number, messages credit remainin~ in credit memor~, cost of current-call, time and date, queùe number and channel identification.
The stored number displa~ allows the handset to be operated as a limited repertory dialling device allowing the recall of one of sa~ ten stored telephone numbars~
~he message indication is used to provide in~ormation to the handset subscriber such as (i) no credit, (ii) transmitter fail (iii) te~minal fail, (iv) out of`~ of terminal, (v) queue position, (vi) date/time error. ~inally the channel identification information is used for identif cation purposes for call back. It should be noted that as the handset sto~es time and date it can be used as a tariff : i . - - . -, ., -- -~723~
computer. ~he terminal unit will also know the date and time and hence can confirm the accuracy of the handset information be~ore accepting a call.
~he ~ush-button keYboard HE is used to enter dialled informa-tion and operating instructions into the micro-processor control system. In addition to the standard digit buttons (0-9) for use in telephone push-button dialling the keyboard is used to enter a user code and to control the display device EICD in addition to providing emergency calls,~a~da~ ~acilities and the controlling of , a signalling tone (bleep) and back space and clear-I operations when entering dialling or facility selection ! informationO ~he keyboard is used to enter the required telephone ~umber (typicall~ country code, area code and called subscribers number) usi~g the push-button switches which are labelled 0 to 9 and presented in the standard push-button dial formation. In addition the keyboard has a user code key which when operated causes the handset identity to be sent to the phone point terminal. ~he handset identity is held in a read-only memory section of the micro-processor~M-C. ~he ke~board also includes a dial-out ke~ for use in controlling dialling and on - repertory dialling operations o~ the handset, a mayda~
key allowing the handset to be used by an incapacitated person for alarm purposes, call cost and credit left display co~trol keys and call back, terminate, bleep on-off and display clear a~d backspace keys.
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~3723 3 _ ~ he handset micro-~rocessor ~M-C provides the ha~dset function control facilities and its operation and performance will be described in more detail later in connection with ~ig. 4. ~he micro-processor operations are initiated by information from the keyboard XE and the digital receiver HD~/R and it controls the display ~ICD, the credit store ~CS and the digital t~ansmitter/receiver HDq!,/R ' ' ' ~he flnal section of the handset involves the equipment used to pro~ide the communication between the handset microphone EM and receiver HR a~d the phone point terminal.
- ~his equipment involves a radio frequency link ha~dling speech in p.c.m. encoded form. As mentioned previously the radio li~k is controlled by a low power crystal oscillator and operates at 100 M~z and p.c.m. encoding techniques are used to modulate the radio frequency links. ~he micro-wave link re~uires that the local oscillator in the ha~dset be a~ stable as possible. ~ig. 3 shows the block diagram of the wa~ in which the local oscillator is locked onto the incoming signal from the phone point terminal with a~
appropriate of~set for the receiver I.~. ~he arrangement of Fig. 3 consists of an image reflection filter IRF fed from the handset aerial HAE. ~he output from the image reflection filter is used to drive a radio frequency amplifier RFA whose output is mixed in mixer M~ with the output from the local oscillator ~0. l'he mixed signal, after I~ filtering (in filter I~F) a~d amplification, (in the I~ amplifier IFA) is fed to the digital transmitter-., . : ,. : :, :
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receiver HD~/R of ~ig. 1 after being demodulated by demodulator DEM. ~he I~ amplifier output iq also used to provide a feedback voltage si~nal proportional to frequenc~
from the converter ~C to control the differential amplifiers OAR and OAS which derive the control signal to the local oscillator IO. Initial acquisition upon switch-on of the handset is performed automatically b~ sweeping the receiYer over the lOO MEz band using a saw-tool search waveform on the lead SW to control the search differential amplifier OAS. ~he possibilit~ that a ~on-phone point terminal transmitter mi~ht ~e incorrectly acquired is dealt with by the micro-processor EM-C which will reject signals having the wrong modulation and cause a search to be continued.
~he output and input paths to the radio frequency transmitter/receiver HRF ~/E~ are controlled b~ the digital .
transmitter-receiver HD~/R which extracts the incoming p.c.m. encoded speech for application to the codec HC
and thence to drive the handset receiver HR. ~he digital transmitter-receiver is also used to allow micro-processor generated i~formation to be passed to the radio frequency transmitter or the handset receiver ~R. ~n example of the latter is in the generation of an alarm tone (called a "bleep") to alert the subscriber to a display condition.
~he function of the digital transmitter-receiver is basicall~ to interface the radio frequency transmitter/
receiver to the codec EC and the micro-processor HM-C.
~he codec EC is used to convert the speech produced ,. ,. .. ~ . ~
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-1~3~3 b~ the handset microphone ~M into p.c.m. encoded form and to convert the p.c.m~ encoded information produced by the di~ital transmitter-receiver HD ~/R into speech to drive the handset receiver ~R. ~ypically the codec used ma~ be that produced by Motrola under code number MC 3418 ~he credit store ECS is used to provide each handset with the facility for paying for the telephone call without a cash transaction at the time of making the call~ ~he contents of the credit store is arranged to be decremented only by the action of the micro-processor ~M-C. ~he credit store is ma~ufactured in such a way that it canno-t be j reproduced or refreshed b~ the use of e~uipment available, ` even with difficulty, to the general public~ ~he credit i store CS uses a derivative of the fusible link programmable memor~ (PROM)~ In the P~OM device an array-of 4,000 I memory cells is formed on a single chip o~ silicon and j each call is connected to the output circuits of the memory chip ~y wa~ of a fine metal link~ In the non-; programmed state the memory when read electrically has 1 20 4,000 cells set to the '1' state. I~ order to program the memory short pulses (of the order of lOu ~econds) of current are applied to the metal links connected to the c~lls which it i~ required to set to the logical 'O' condition. ~hese pulses o~ current fuse the metal links and destro~ the connection to the output circuits. ~he energy reauired to ~use a link is on the order of lOOu Joules which is provided by a battery used to power the ; handset. After each phone point call the micro-processor , ... .. . .
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~L~L3~239 HM-C computes the call charge and causes the necessary ~used li~ks to be disrupted to delete that credit value from the credit store. ~ new PROM is installed into the unit when the previous credit lèvel is exhau~ted; typically a 4,000 bit capacity cartridge with a charging rate of say 3p per unit would provide a credit capacity of ~120.
~ he phone Point terminal unit is shown in ~ig~ 2 and it consists of a micro-processor control system ~M-C, a message store MS, a radio ~requency transmitter ~R~ and a radio frequency receiver ~RFR~, a digital transmitter--,receiver ~D~/R, a codec ~C and a telephone network 1ineinterface UDit ~1.
~ he te~minal micro-processor ~-C provides the terminal UDit control facilities and its operation and performance will be described in more detail later; in co~nection with ~ig. 5. ~he micro-processor normally functions in a background mode looking for a calling h~ndset or a~ incoming call from the P~ network ~0 In addition the micro-processor ~M-C is provided with an emergency input EI which ma~ be used to cause the micro processor to respond to the activatio~ of an emergency button on the phone point terminal to handle Police, ~ire or Ambula~ce calls originated without a phone-point' handset. Associàted with the micro-processor ~M-C is a message store MS which is used (i) to qtore messages generated by handsets which have used the phone point -- system to ~et-up a call to a busy telephone system subscriber and (ii) to stoxe messages ~or phone point handset subscribers.
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-~37239 The micro-processor is also provided with a dialling information path DI for use in setting-up a telephone call from the phone point terminal to a telephone subscriber.
Communication between the handsets and the micro-processor in the termlnal unit involves the radio frequency links and the digital transmitter receiver. Finally an alarm device AD is associated with the terminal unit micro-processor to indicate that there is an incoming telephone system call waiting at the terminal unit.
I~ ~ig. 2 there is shown a broken line box referenced Pæa~ and this indicates that a number of communication channels are provided at a terminal unit and each communication channel e~fectively has the use of equipment shown within the box PPC~ addition the radio frequency receiver ~R~R~ is used to listen ~or a control channel request signal and the micro-processor ~M-C will commu~icate with the "calling" phone point handset using the digital transmitter-receiver ~D~R and the radio ~reauency trans-m tter ~R~
- 20 ~o more readily u~derstand the operation of the phone point system the interaction of a ha~dset and the terminal unit will be co~sidered by following the actions of these equipments in the e~ecution of a simple phone point call. ~igs. 4 and 5 show the flow diagrams of the operations performed and these figures will be used to aid the understanding of the operations reauired.
~ig~ 4 shows the operations per~o~med by the handset whereas ~ig. 5 shows the operations performed by the phone . . : ,. .
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point terminal unit. ~he following description will be sectloned under the headings of the steps shown in ~igs.
4 and 5.
~à initiate a phone point call a phone point subscriber positions himself within a short distance from the phone point texminal unit a~d opens the case of his handset.
Step SHl - Case oe_~_handset on l'he opening o~ the handset case causes the power to the ha~dset equipment to be switched on and an automatic routine is entered involving step ~H2 to 8 to "connect"
the handset with a communication ch~nnel of the terminal U~it.
~tep SH2_- ~erminal_sig~al level satisfa~
I~ this step the local oscillator looks for the phone poi~t terminal transmitter and the micro-processor tests the sig~al level generated at the output of the digital t~ansmitter-receiver HD~/R of ~ig. 13 If the signal level is not satisfactory the micro-processor produces a p.c.m. code which is fed to the digital transmitter/receiver HD~/R and the codec HC to cause a bleep tone to be produced b~ the handset receiver H~ and the display HICD is driven by the micro-processor to indicate that the signal level is unsatisfactory and a pho~e point communication can not be set-up. If the terminal signal is satisfactor~ step ~3 is performed.
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In this step the operations defined in ~ig. 3 are performed to lock to local oscillator ~0. Of the handset . .
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~L3723 _ l9 _ to the frequency of the terminal. ~he micro-processor controls the application of the search waveform SW of ~ig. 3 until the local oscillator is s~nchronised. If synchronisation is not achieve~ again a "bleep" warning is generated and the handset~displa~ is activated to indicate a s~nchronisation failure. Alternatively when the handset - local oscillator has been synch~onised with the terminal carrier~ Step SH4 is performedO
Step ~H4 - Check Control Channel In this step the micro-processor conditions the digital transmitter receiver HD~R to extract the information f~om the received signal from the terminal unit corresponding to the common con~rol channel. As mentioned above the phone point terminal unit handles a number of communication channels and common to all these GommUniCation channels is one control channel which is used only during the initial period of a phone Point call by a handset until a communica-tion channel is allocatedO
In this step the common control channel extracted by the digital transmitter receiver HD~/R is tested to see i~
it is f~ee. I the commo~ control channel is not free (i.e. a~other ha~dset is setting-up a phone point call) the handset remains in the loop provided b~ steps SE4 and SH5 u~til the channel is free when step SH6 will be performedO
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In this step the micro-processor HM-C inserts into the control cha~nel, b~ way of the digital transmitter and : ' . ~.' :: , ~ ` . :
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the transmitter part of the radio frequency link, a request communication channel code. ~his code will be passed to the phone point terminal where it will be detected to cause entry into the phone polnt ~erminal call set-up procedure shown in ~ig. 5.
Ste S~l - Is Communication Channel available I~ thisstep the micro-processor ~M-C will detect, using the digi~al transmitter receiver I9 I/R that a communication request has been received on the common channel and it tests to see if there is a free communication channel available. If there is not step S~2 is performed whereas step SI3 is performed i~ there is a free communication ~¦ cha~nel available.
-¦ Step ~2 - Send Queue ~umber ! 15 In this step the terminal micro-processor ~M-C
j inserts into the control ch nnel~ through the digital ! transmitter-receiver ~D~/R, informa~ion indicative of the number in the queue the calling handset has been allocated.
~his information having been sent to the calling handset-over the commou channel will cause its step SE7 (~ig 4 to be exited by way of the "no" path whereas the phone point terminal-will return to a background program awaiting ; demands or information from other handsetsO
Ste~ S _-_Communication Cha~nel available?
In this step of the handset program the reception of the queue number over the common ch~nnel will cause a "bleep" to be generated in the handset receiver HR and the queue number allocated by the terminal (in step S~2 .. ... .
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~37239 above) will be displayed on the display HICD.
Step SM8 - Wait 5 seconds In this step the program is suspended awaiting a five second time out before repeatin~ steps S~4, S~5, SH6, SE7 and SE8 etc. until step SH7 ca~ be exited u~ing the "yes"
path. ~or each entry into step S~6 an entr~ is made into step S~l in the phone point terminal. Ultimately there will be a communication channel available and the terminal will execute step S~3.
Step S13 - Send Communication Channel number I~ this step the micro-processor ~M-C injects into the contxol channel, using the digital tra~smitter-receiver ~D~/R in~ormation indicative of the number of a commlln;ca-tion channel allocated to the callin6 handset. ~he terminal unit now enters the loop formed b~ steps S~4 and S~5 awaiting for the dial information from the calling handset.
In this step the output from the digital transmitter receiver D~/R for the commu~ication channel allocated to the c~lling handset is interrogated.
In this step the information derived from the channel -~ allocated to the calling handset is tested by the micro-processor ~M-C to see if it is ~e&~g informatio~ if it is not then step S~4 is re-entered~
~ he performance of step S~3 by the terminal will cause step SE7 in the calling handset to be exited on the "~es"
path into step SH8 (of ~ig~ 4).
, ~3L3723S~
Step ~H8 - Set Eandset to ~llocated Channel ~his step i9 entered because the micro-processor will have detected the reception of the communication ch~nnel identity in the commo~ channel produced by the digital transmitter/receiver ~D~/R output.` ~he reception of the communication chpnnel identity causes the micro-processor to condition the radio-frequency transmitter~
receiver HRP~x/R~ to adjust its radio frequency circuit to set to the allocated commuDication ch~nnel. At the same time the digital transmitter receiver ED~/R is conditioned to produce a "bleep" in the handset receiver HR and the display device ~CD is operated to indicate "start dialling".
~he phone point subscriber ~ow starts dialling the number he requires usin~ the push-button ke~board HE to enter the required telephone number into the micro-processor HM-C~
Step SH9 - Store a}~L~g}~gy~ a~formation ~he micro-processor is arranged to receive the dialled information ~rom the keyboard HE and to display the telephone number so compiIed. Upon completion o~ the dialling information the handset waits for the dial-out com~l~nd ke~
o~ the keyboard HE to be operated. ~his allows the subscriber to check that he has keyed in the required telephone number correctly.
Step SH10 - Dial out comm ~
In this step the operation of the dial~out command key is tested for. If it is not operated step SHll is performed to clear the di~lling store in the micro-processor ~M~C and to ca~cel the information on the displa~ HLCD.
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: . :, ., : ,., ~113723 When the dial-out command is received Step SHl2 is per~ormed.
Step S~2 - Send number_out over link In this step the micro-processor ~M-C injects the di~lling information into the allocated communic~tion ch~nnel using the digital transmitter-receiver ~D~/R. ~his dialling information will be passed over the allocated commun'cation channel lnvolving the microwave link between the handset and the termi~al and step S~5 ~Fig. 5) will be ~ exited using the "yes" path.
i lO Step S 6 - Buffer dial information to network In this step the received dialling information is ¦ received by the micro-processor ~M-C from the allocated communication channel by wa~ o~ -the digital transmitter-receiver ~D?/R. As the dialling information is received 1 15 the micro-processor ~M-C converts that information into ~ suitable form for transmission to the telephone network ', a~d this converted information is passed over lead DI to the line interface equipment of the telephone network line corresponding to the allocated channel~ ~he terminal will circulate in steps ~6 and S~7 u~til the di311ing out over the line interface is complete. Eaving sent the dialli~g information out over the communication channel the handset performs step SHl3.
In this step the micro-processor ~M-C connects the digital transmitter receiver HD~/R through to the codec EC
thereb~ connecting the handset microphone ~M and receiver ; ~R through to the allocated communication chPnnel. At the ,. . ~ .
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~L37~3~
_ 24 -same time the terminal will have completed its dialling-out operation entering step S~8 (~ig. 5).
Step S~8 - Establish Audio,_path In this step the micro-processor ~M-C will connect the allocated communication channel to the line interface ~I serving that telephone network termination taken into use by the micro-processor ~M-C to repeat the dialling information~ ~his.makes the "audio" path from the line inter~ace through to the handset microphone ~M and receiver ER. ~he terminal now returns -to a background program allowing other phone point calls to be serviced. ~he rest of the c 1-1 until it is termi~ated will be administered b~ the handset performing steps SHl4~16.
Ste ~
15 In this step the micro-processor H~-C will detect the set-up of the telephone call (i.e. when the called sub answers). ~his i9 used to start the accounting function for the caIl. ~ypicall~ the micro-processor EM-C in the handset knows the called ~umber and it knows the time oX day so it ca~ start mo~itoring the call loo~ing for a call term~nate co~dition to be able to calculate the cost of the call to be deleted from the credit store ECS. ~hese steps are shown i~ ~i30~. 4 at ~Hl4, SHl5, SHl6 and S~17.
~he micro-processor HM-C will record the time of day at which this occurs and wlth reference to the ~umber dialled, it can calculate the cost o~ the call in accordance with internall~ store call charges~ ~ call termination ma~ be ,::
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-as a result o~ the Subscriber ~olding up his handset or operating the call terminate button or the keyboard HE.
Ste~ SH17 - Decrement credit store In this step the call cost calculated in steps SRn5 and 16,is decremented from the credit store ~C~. ~his terminates the operation of the phone point s~stem eauipment.
~he above description has been o~ one simple embodiment ,only and is not,intended to be limiting to the invention.
Many alternative arrangements can be envisaged by those skilled in the art, for example the above description has indicated that the credit store is decremented in accordance , with an internal calculation performed b~ the micro-processor of the handset. An alternative arrangement could be provided where the phone point terminal generates metering information ~` 15 which is communicated over the allocated communication channel to the handset. Further the flow diagram of ~igs~
4 ,and 5 are necessaril~ brief and many routes allowing for call abandonment have not been shown~ Purther to validate the phone point system an automatic interchange can be included in the initial p,hone point system call set-up procedure involving the ~ndset intarnal identity in~o~mation exchange and the checking of the handset internal cloc~/
date mechanism. ~inally the way the phone point terminal inter~aces to the telephone system obviously depends upon the telephone system involved. ~ypically one line interface may be provided for each netwGrk termination or a single termination may be time division multiplex shared by a number of phone point ch~nnels. Finally a "credit card"
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~ ~137239 ~, s~stem co~d be u~ed in place of the credit store with the card number permanentl~ in the hand~et and with central call accounting performed using information on the call and credit card number located in the phone point terminal.
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~I~'LE: ~LECOMMUNICA~ION SYS~M I~CORPORA~ING
POR~ABIE COMMU~ICA~IO~ UNI~S
~ `he present invention relates to telecommunications systems and is more particularly concerned with.improving the facilities currentl~ provided by public call-office kiosks and the like.
During recent years the telepho~e system has been expanded to allow data communication to be added to speech communication between subscribers. ~uch data com~unication facilities, however, have had limited penetration, as far as the total subscriber's on a national telephone network is concerned, mai~l~ because relatively expensive modem and hard copy printer and ke~board communication equipment is required at each end o~ a communication connection. In the main people are, however, periphatetic and it is necessar~ for communication system~ to recognise that subscribers require to make telecommunicatio~ caIls as they move around from their natural ba~e, for example as they travel from home to office, travel away on business or on holidayO At present7 however, onl~ a few people with radio-telephone equipment can actually take their communication equipment with them. ~or the remainder public call offices and renters pa~-phones must suffice.
According to the invention there is provided a telecommunication s~stem ha~ing a pluralit~ of communication terminals connected to the switching network of the system, each communication te~minal being arranged to co~operate with a pluralit~ of portable communication units each of .
, s 37i~3~
_ ~ _ which is adapted to co-operate with a~ of the communication terminals to set-up telecommunication càlls involving the network to netwoxk terminations and each portable communication unit includes a call tariff charging arrangement adapted to be used to account for the usage of the portable communication unit o~ chargeable telecommunication calls involving the network.
~ he present in~ention envisages a telecommunication system ha~ing a pluralit~ of subscribers terminals and a 10. pluralit~ of communication terminals connècted to the networ~ of the s~stem, each communication terminal is arranged to co-operate with a pluralit~ of portable commu~ication units a~d each portable communication unit ` i9 adapted to co-operate with any of said communication terminals to set-up telecommu~ication calls i~volving the . network and a portable communication unit to a~y of the subscribers terminals on the network and each portable communication u~it includes means for coupling the portable communication unit to a communication te~minal, means for txansmitting telecommunication network control information and communication informatio~ to a commu~ication te~minal, mea~s for receiving telecommunication information from a commllnication terminal and telecommunication tariff credit metering arrangements adapted to decrease the telecommunica-tion call charge credit of the handset in accordance withthe telecommunication call usage of the handset and each communication terminal includes means for inter~acing the portable communication units with the telecommunications ., . , :, . , , :. , .~ , ,: . ~
1137~
network including mea~s for receiving telecommlln;cation in~ormation from a portable communication unit and means ~or transmitting telecommunications information to a portable communication unit.
In one embodiment of the invention the co~munication terminal unit includes means for computing tarif~ credit metering adaustment information from the network tariff metering informatio~ and means for communicating the adjustment information to the portable communications unit to modify the contents o~ the credit metering arrangement.
In a simple interpretation of the invention individual users of the arrangement are provided with portable telephone units which are physically similar to a pocket calculator and include a telephone transm~tter, receiver, key pad unit and call credit store. ~he portable communica-tion unit is arranged to co-operate with the communication terminal, coupling between being by radio, inductive loop, optical radiation, ultrasonic coupling, hard wire ccupling or the like~
I~ order to make a telecommunications call, the user positions himsel~ within some standard distance, say five meters, of one of the communication termi~al and then op~rates his portable communication llnit to gain access to the telephone system to make a telephone call. ~he communication terminal ma~ be mounted at any convenient position whether on a post, wall or roof for example.
~he communications terminal need be o~ small size and is arranged to operate unattended. It ma~ be hidden behind a ...... .-~37239 facade say three meters above ground level and marked with a logo such as "phone point". Accordi~gl~ the communications terminal occupies little or no space, as compared with the conventional kiosk and is not accessible to vandals. ~he portable telephone unit comprises a push-button key pad for dialling, a displa~ device and an integral earpiece together with a microphone which for example is extendable to the normal spacing from the earpiece using an acoustic tube. ~ccess to the telephone s~stem is gained by touching a key code sequence on the poxtable telephone unit, when the user is within range of the terminal unit. When access is confirmed, the user keys in the standard area code plus the required telephone number and when the call is established the communication terminal indicates cost information over the reverse communication link to the portable telephone unit~ ~he credit meter arrangement is amended by this i~formation.
In more extensive interpretations a poxtable commu~ications unit ma~ be arranged to incorporate the equipment nece~sary for the setting-up of data communication connections with the portable communication u~it including a data modem, hard copy pri~ter and keyboard in addition to the call tariff metering arrangementr In such circumstances the communication terminal will act as a normal telecommunica-tions connection interfacing the portable communication unitto the telephone network. Alternatively the communication terminal may be provided with the modem facility and the portable communication unit with the printer and keyboard . .
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~372~
facilit~ only in addition to its call tariff metering arrangement and normal telephone connection ~acilities.
Each communication terminal is arranged to provide telecommu~icatio~ facilibies for a number of portable communication units allowing simultaneous commlln;cation calls to be in being at the same timeO Combinations of differing types of telecommunicatio~s calls involving voice communication and or data communication will be handled by the communication terminal. ~he communication terminal 10 - unit is arranged to handle for example eight communication chPnnels and is provided with one common control chPnnel.
~he common control channel is used to set-up the initial connection between a "calling" handset and the termi~al u~it which, upon vaIidation of the interchauge between the handset and terminal unit, allocates one of the communica-tion ch~nnels which is used thereafter for telecommuLication signalling and communication purposes for the duration of the call~
~n addition the communications terminal ma~ also be provided with so-called "teletext" or "view data" facilities allowing a subscriber with a portable communications unit incorporating the necessary interrogation facilities to ~se~
communication with the Pr~~,-Or~CT~ a~d CEE~A~ systems as required.
~urther the communication ter~inal may be provided with store and forward facilities allowing messages to be stored for passage to a busy subscribers terminal at a later date. ~picall~ store and forward messages could be held ,:; . ,:. .- .:: , , . ,:, .,, . .: .
:, ~ ~3~Z39 _ in the communication terminal for transmission outside the busy periods of commuDication activity allowing the recorded message to be sent at the low tariff rate after having being recorded during a higher tariff rate period~
Under such circumstances the communication terminal will compute the lower tariff and arrange for the credit store arrangement in the portable communication unit u~ed in making the recorded message to be adjusted accordingly.
~ypically the credit store arrangement comprises a programmable read only memory and tariff information I communicated from the communication terminal is used to ! erase the credit progressively from the memory~
I ~he portable communication unit is arranged to include a display device, typicall~ of the liquid crystal type, t 15 which may be used to indicate the cost of an individual telecommunication call and the amount of credit left in the portable communication unit. In addition the displa~
may be used to in~icate the telephone nùmber dialled to validate the integxity of the reverse link betwee~ the i 20 portable communication unit and the commu~ication te~minal.
~he invention, together with its various features will be more readily understood ~rom the following description which should be read in conjunction with the aCcQmpa~ying drawings. Of the drawings:-Fig. 1 shows in block diagram form, the equipment necessary ~or the handset or portable communication unit, Fig. 2 shows in block diagram form, the equipment necessary fox the "phone point" terminal or communication .
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terminal, ~ ig. 3 shows the radio frequency stability control section of the portable commum cation unit, ~ ~igo 4 shows a flow diagram of the operations performed b~ the h~ndset in the execution of a call whereas Fig. 5 shows a flow diagram of the operations performed b~ the phone poin-t terminal in the handling of a call.
In the following description the handset refers to the portable communicatio~ unit whereas the phone point terminal refers to the communication terminal.
Before embarking upon a detailed discussion of the e~uipment used in the handset and communication te~minal unit of the invention con~ideration will be given to the overall new telecommunication s~stem ~acilities which may be provided by the e~uipment of the invention. Hereafter -the new s~stem will be referred to as phone point. ~he two maaor elements of the phone point s~stem are (i) a portable teIecommunications handset incorporating a micro-processor which controls the handling o~ telecommu~ication calls a~d the accountancy for those calls and-~ii) a communication -terminal also micro-processor controlled and arranged to handle a number of handset calls at any one time and to interface the handsets into the normal telecommunication network conmunicating call accountancy information to the handset communication with the terminal. ~gpically the handset comprises a minature push-button telepho~e instrument of the size of a pocket calculator which includes a display device, a micro~processor, a credit store memo~, a -- - -1~37;~;~9 telecommunication transmitter and receiver and equipment for co~municating with the terminal unit. ~he handset when not in operation ma~ be folded up so that it ma~ be carried in a suit pocket or handbag. When it is required to use the handset it is opened up so that it forms a telephone instrument handset. ~he terminal unit of the phone point system is used to interface the handsets to the normal telecommunication network.
~ypically the phone point terminal ~lnits are provided in public places such as airport terminals, railway stations, theatre foyers1 shopping precincts and the like in a similar manner to present day telephone kiosks. ~owever the phone point terminal unit is not equipped with a telephone instrument handset or coin collecting equipment.
Subscribers to the phone point system are allocated their own portable handsets which in the simplest interpretation of the phone point system include a telephone call credit store. A subscriber wishing to make a phone point call simply positions himself within a short distance~ say 5 meters, of a phone point terminal unlt and uses his handset to set-up a telephone call by way of the phone point te~minal unit.
Commu~ication between the handsets and each phone point terminal unit involves radio com~unication involving microwave communication links. ~ach phone point terminal is provided with one common control chAnnel and eight communication channels. lhe common control ch~nnel is used during initial set-up between a handset and a phone :: --~37~;~9 point terminal unit before an available communication cha~nel is allocated ~or use on a telephone call. During a telephone call the call credit memory in the handset is adjusted i~ accordance with the cost of the ~elephone call made. At the end of the call the subscriber may control the handset micro-processor to operate the handset display to indicate the total cost of the completed call and the remaining credit in the credit memory.
~ach phone point terminal unit is arranged to handle concurrentl~ a number of phone point calls and the terminal unit incorporates equipment for interfacing the so calls to the telephone network.
~ rom the above it can be see~ that the pho~e point system is analogous to present day telephone kiosk systems but with the particular added advantages of enhancing service availability, using the network more efficiently and providing isolated call accountancy management. The service availability is enhanced because the intrinsic total terminal capital cost is lower since each terminal can be used by a number of subscribers simultaneousl~.
~etwork utilisation is increased because of the ease of use of the terminals-and concentration o~ facilities and because of the simpli~ied credit/cash management system.
~he use o~ a credit memory in each handset which retains either the level of credit purchased in advance by the subscriber or by direct debiting by a central charging system improves the telecommunications administrations cash flow and removes the security hazard presented by cash-. : , . ..
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~37~39 boxes in telephone kiosks.
Consideration will now be given to the equipment used in a handset and a commlLnication terminal unit in the phone point s~stem.
~he handset equipment is ~hown in ~ig. 1 and consists of a liquid cr~stal displa~ device HICD, a push button ke~board HE, a micro~processor based operation control system ~M-C, a call credit store ECS, a telephone instrument transmitter H~ and receiver ~R and a low power crystal controlled radio link HRE~/K~ which handles di~ital information derived from speech using pulse code modulation techni~ues involving the codec ~C and~the digital tra~smitter-receiver H 9~-R.
~ ~ is operated under micro-processor control to display the following information:- telephone ~umber dialled, stored number, messages credit remainin~ in credit memor~, cost of current-call, time and date, queùe number and channel identification.
The stored number displa~ allows the handset to be operated as a limited repertory dialling device allowing the recall of one of sa~ ten stored telephone numbars~
~he message indication is used to provide in~ormation to the handset subscriber such as (i) no credit, (ii) transmitter fail (iii) te~minal fail, (iv) out of`~ of terminal, (v) queue position, (vi) date/time error. ~inally the channel identification information is used for identif cation purposes for call back. It should be noted that as the handset sto~es time and date it can be used as a tariff : i . - - . -, ., -- -~723~
computer. ~he terminal unit will also know the date and time and hence can confirm the accuracy of the handset information be~ore accepting a call.
~he ~ush-button keYboard HE is used to enter dialled informa-tion and operating instructions into the micro-processor control system. In addition to the standard digit buttons (0-9) for use in telephone push-button dialling the keyboard is used to enter a user code and to control the display device EICD in addition to providing emergency calls,~a~da~ ~acilities and the controlling of , a signalling tone (bleep) and back space and clear-I operations when entering dialling or facility selection ! informationO ~he keyboard is used to enter the required telephone ~umber (typicall~ country code, area code and called subscribers number) usi~g the push-button switches which are labelled 0 to 9 and presented in the standard push-button dial formation. In addition the keyboard has a user code key which when operated causes the handset identity to be sent to the phone point terminal. ~he handset identity is held in a read-only memory section of the micro-processor~M-C. ~he ke~board also includes a dial-out ke~ for use in controlling dialling and on - repertory dialling operations o~ the handset, a mayda~
key allowing the handset to be used by an incapacitated person for alarm purposes, call cost and credit left display co~trol keys and call back, terminate, bleep on-off and display clear a~d backspace keys.
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~3723 3 _ ~ he handset micro-~rocessor ~M-C provides the ha~dset function control facilities and its operation and performance will be described in more detail later in connection with ~ig. 4. ~he micro-processor operations are initiated by information from the keyboard XE and the digital receiver HD~/R and it controls the display ~ICD, the credit store ~CS and the digital t~ansmitter/receiver HDq!,/R ' ' ' ~he flnal section of the handset involves the equipment used to pro~ide the communication between the handset microphone EM and receiver HR a~d the phone point terminal.
- ~his equipment involves a radio frequency link ha~dling speech in p.c.m. encoded form. As mentioned previously the radio li~k is controlled by a low power crystal oscillator and operates at 100 M~z and p.c.m. encoding techniques are used to modulate the radio frequency links. ~he micro-wave link re~uires that the local oscillator in the ha~dset be a~ stable as possible. ~ig. 3 shows the block diagram of the wa~ in which the local oscillator is locked onto the incoming signal from the phone point terminal with a~
appropriate of~set for the receiver I.~. ~he arrangement of Fig. 3 consists of an image reflection filter IRF fed from the handset aerial HAE. ~he output from the image reflection filter is used to drive a radio frequency amplifier RFA whose output is mixed in mixer M~ with the output from the local oscillator ~0. l'he mixed signal, after I~ filtering (in filter I~F) a~d amplification, (in the I~ amplifier IFA) is fed to the digital transmitter-., . : ,. : :, :
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receiver HD~/R of ~ig. 1 after being demodulated by demodulator DEM. ~he I~ amplifier output iq also used to provide a feedback voltage si~nal proportional to frequenc~
from the converter ~C to control the differential amplifiers OAR and OAS which derive the control signal to the local oscillator IO. Initial acquisition upon switch-on of the handset is performed automatically b~ sweeping the receiYer over the lOO MEz band using a saw-tool search waveform on the lead SW to control the search differential amplifier OAS. ~he possibilit~ that a ~on-phone point terminal transmitter mi~ht ~e incorrectly acquired is dealt with by the micro-processor EM-C which will reject signals having the wrong modulation and cause a search to be continued.
~he output and input paths to the radio frequency transmitter/receiver HRF ~/E~ are controlled b~ the digital .
transmitter-receiver HD~/R which extracts the incoming p.c.m. encoded speech for application to the codec HC
and thence to drive the handset receiver HR. ~he digital transmitter-receiver is also used to allow micro-processor generated i~formation to be passed to the radio frequency transmitter or the handset receiver ~R. ~n example of the latter is in the generation of an alarm tone (called a "bleep") to alert the subscriber to a display condition.
~he function of the digital transmitter-receiver is basicall~ to interface the radio frequency transmitter/
receiver to the codec EC and the micro-processor HM-C.
~he codec EC is used to convert the speech produced ,. ,. .. ~ . ~
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-1~3~3 b~ the handset microphone ~M into p.c.m. encoded form and to convert the p.c.m~ encoded information produced by the di~ital transmitter-receiver HD ~/R into speech to drive the handset receiver ~R. ~ypically the codec used ma~ be that produced by Motrola under code number MC 3418 ~he credit store ECS is used to provide each handset with the facility for paying for the telephone call without a cash transaction at the time of making the call~ ~he contents of the credit store is arranged to be decremented only by the action of the micro-processor ~M-C. ~he credit store is ma~ufactured in such a way that it canno-t be j reproduced or refreshed b~ the use of e~uipment available, ` even with difficulty, to the general public~ ~he credit i store CS uses a derivative of the fusible link programmable memor~ (PROM)~ In the P~OM device an array-of 4,000 I memory cells is formed on a single chip o~ silicon and j each call is connected to the output circuits of the memory chip ~y wa~ of a fine metal link~ In the non-; programmed state the memory when read electrically has 1 20 4,000 cells set to the '1' state. I~ order to program the memory short pulses (of the order of lOu ~econds) of current are applied to the metal links connected to the c~lls which it i~ required to set to the logical 'O' condition. ~hese pulses o~ current fuse the metal links and destro~ the connection to the output circuits. ~he energy reauired to ~use a link is on the order of lOOu Joules which is provided by a battery used to power the ; handset. After each phone point call the micro-processor , ... .. . .
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~L~L3~239 HM-C computes the call charge and causes the necessary ~used li~ks to be disrupted to delete that credit value from the credit store. ~ new PROM is installed into the unit when the previous credit lèvel is exhau~ted; typically a 4,000 bit capacity cartridge with a charging rate of say 3p per unit would provide a credit capacity of ~120.
~ he phone Point terminal unit is shown in ~ig~ 2 and it consists of a micro-processor control system ~M-C, a message store MS, a radio ~requency transmitter ~R~ and a radio frequency receiver ~RFR~, a digital transmitter--,receiver ~D~/R, a codec ~C and a telephone network 1ineinterface UDit ~1.
~ he te~minal micro-processor ~-C provides the terminal UDit control facilities and its operation and performance will be described in more detail later; in co~nection with ~ig. 5. ~he micro-processor normally functions in a background mode looking for a calling h~ndset or a~ incoming call from the P~ network ~0 In addition the micro-processor ~M-C is provided with an emergency input EI which ma~ be used to cause the micro processor to respond to the activatio~ of an emergency button on the phone point terminal to handle Police, ~ire or Ambula~ce calls originated without a phone-point' handset. Associàted with the micro-processor ~M-C is a message store MS which is used (i) to qtore messages generated by handsets which have used the phone point -- system to ~et-up a call to a busy telephone system subscriber and (ii) to stoxe messages ~or phone point handset subscribers.
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-~37239 The micro-processor is also provided with a dialling information path DI for use in setting-up a telephone call from the phone point terminal to a telephone subscriber.
Communication between the handsets and the micro-processor in the termlnal unit involves the radio frequency links and the digital transmitter receiver. Finally an alarm device AD is associated with the terminal unit micro-processor to indicate that there is an incoming telephone system call waiting at the terminal unit.
I~ ~ig. 2 there is shown a broken line box referenced Pæa~ and this indicates that a number of communication channels are provided at a terminal unit and each communication channel e~fectively has the use of equipment shown within the box PPC~ addition the radio frequency receiver ~R~R~ is used to listen ~or a control channel request signal and the micro-processor ~M-C will commu~icate with the "calling" phone point handset using the digital transmitter-receiver ~D~R and the radio ~reauency trans-m tter ~R~
- 20 ~o more readily u~derstand the operation of the phone point system the interaction of a ha~dset and the terminal unit will be co~sidered by following the actions of these equipments in the e~ecution of a simple phone point call. ~igs. 4 and 5 show the flow diagrams of the operations performed and these figures will be used to aid the understanding of the operations reauired.
~ig~ 4 shows the operations per~o~med by the handset whereas ~ig. 5 shows the operations performed by the phone . . : ,. .
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point terminal unit. ~he following description will be sectloned under the headings of the steps shown in ~igs.
4 and 5.
~à initiate a phone point call a phone point subscriber positions himself within a short distance from the phone point texminal unit a~d opens the case of his handset.
Step SHl - Case oe_~_handset on l'he opening o~ the handset case causes the power to the ha~dset equipment to be switched on and an automatic routine is entered involving step ~H2 to 8 to "connect"
the handset with a communication ch~nnel of the terminal U~it.
~tep SH2_- ~erminal_sig~al level satisfa~
I~ this step the local oscillator looks for the phone poi~t terminal transmitter and the micro-processor tests the sig~al level generated at the output of the digital t~ansmitter-receiver HD~/R of ~ig. 13 If the signal level is not satisfactory the micro-processor produces a p.c.m. code which is fed to the digital transmitter/receiver HD~/R and the codec HC to cause a bleep tone to be produced b~ the handset receiver H~ and the display HICD is driven by the micro-processor to indicate that the signal level is unsatisfactory and a pho~e point communication can not be set-up. If the terminal signal is satisfactor~ step ~3 is performed.
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In this step the operations defined in ~ig. 3 are performed to lock to local oscillator ~0. Of the handset . .
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~L3723 _ l9 _ to the frequency of the terminal. ~he micro-processor controls the application of the search waveform SW of ~ig. 3 until the local oscillator is s~nchronised. If synchronisation is not achieve~ again a "bleep" warning is generated and the handset~displa~ is activated to indicate a s~nchronisation failure. Alternatively when the handset - local oscillator has been synch~onised with the terminal carrier~ Step SH4 is performedO
Step ~H4 - Check Control Channel In this step the micro-processor conditions the digital transmitter receiver HD~R to extract the information f~om the received signal from the terminal unit corresponding to the common con~rol channel. As mentioned above the phone point terminal unit handles a number of communication channels and common to all these GommUniCation channels is one control channel which is used only during the initial period of a phone Point call by a handset until a communica-tion channel is allocatedO
In this step the common control channel extracted by the digital transmitter receiver HD~/R is tested to see i~
it is f~ee. I the commo~ control channel is not free (i.e. a~other ha~dset is setting-up a phone point call) the handset remains in the loop provided b~ steps SE4 and SH5 u~til the channel is free when step SH6 will be performedO
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In this step the micro-processor HM-C inserts into the control cha~nel, b~ way of the digital transmitter and : ' . ~.' :: , ~ ` . :
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.
the transmitter part of the radio frequency link, a request communication channel code. ~his code will be passed to the phone point terminal where it will be detected to cause entry into the phone polnt ~erminal call set-up procedure shown in ~ig. 5.
Ste S~l - Is Communication Channel available I~ thisstep the micro-processor ~M-C will detect, using the digi~al transmitter receiver I9 I/R that a communication request has been received on the common channel and it tests to see if there is a free communication channel available. If there is not step S~2 is performed whereas step SI3 is performed i~ there is a free communication ~¦ cha~nel available.
-¦ Step ~2 - Send Queue ~umber ! 15 In this step the terminal micro-processor ~M-C
j inserts into the control ch nnel~ through the digital ! transmitter-receiver ~D~/R, informa~ion indicative of the number in the queue the calling handset has been allocated.
~his information having been sent to the calling handset-over the commou channel will cause its step SE7 (~ig 4 to be exited by way of the "no" path whereas the phone point terminal-will return to a background program awaiting ; demands or information from other handsetsO
Ste~ S _-_Communication Cha~nel available?
In this step of the handset program the reception of the queue number over the common ch~nnel will cause a "bleep" to be generated in the handset receiver HR and the queue number allocated by the terminal (in step S~2 .. ... .
; ,,, . ~ - .::
. , :
: .. ..
~37239 above) will be displayed on the display HICD.
Step SM8 - Wait 5 seconds In this step the program is suspended awaiting a five second time out before repeatin~ steps S~4, S~5, SH6, SE7 and SE8 etc. until step SH7 ca~ be exited u~ing the "yes"
path. ~or each entry into step S~6 an entr~ is made into step S~l in the phone point terminal. Ultimately there will be a communication channel available and the terminal will execute step S~3.
Step S13 - Send Communication Channel number I~ this step the micro-processor ~M-C injects into the contxol channel, using the digital tra~smitter-receiver ~D~/R in~ormation indicative of the number of a commlln;ca-tion channel allocated to the callin6 handset. ~he terminal unit now enters the loop formed b~ steps S~4 and S~5 awaiting for the dial information from the calling handset.
In this step the output from the digital transmitter receiver D~/R for the commu~ication channel allocated to the c~lling handset is interrogated.
In this step the information derived from the channel -~ allocated to the calling handset is tested by the micro-processor ~M-C to see if it is ~e&~g informatio~ if it is not then step S~4 is re-entered~
~ he performance of step S~3 by the terminal will cause step SE7 in the calling handset to be exited on the "~es"
path into step SH8 (of ~ig~ 4).
, ~3L3723S~
Step ~H8 - Set Eandset to ~llocated Channel ~his step i9 entered because the micro-processor will have detected the reception of the communication ch~nnel identity in the commo~ channel produced by the digital transmitter/receiver ~D~/R output.` ~he reception of the communication chpnnel identity causes the micro-processor to condition the radio-frequency transmitter~
receiver HRP~x/R~ to adjust its radio frequency circuit to set to the allocated commuDication ch~nnel. At the same time the digital transmitter receiver ED~/R is conditioned to produce a "bleep" in the handset receiver HR and the display device ~CD is operated to indicate "start dialling".
~he phone point subscriber ~ow starts dialling the number he requires usin~ the push-button ke~board HE to enter the required telephone number into the micro-processor HM-C~
Step SH9 - Store a}~L~g}~gy~ a~formation ~he micro-processor is arranged to receive the dialled information ~rom the keyboard HE and to display the telephone number so compiIed. Upon completion o~ the dialling information the handset waits for the dial-out com~l~nd ke~
o~ the keyboard HE to be operated. ~his allows the subscriber to check that he has keyed in the required telephone number correctly.
Step SH10 - Dial out comm ~
In this step the operation of the dial~out command key is tested for. If it is not operated step SHll is performed to clear the di~lling store in the micro-processor ~M~C and to ca~cel the information on the displa~ HLCD.
., .. . . 1 . ..
. : : -.
. , ~ ", - -: ~ , , . ~ . : . .
.. .. . ..
. ~ . , , . :.
: . :, ., : ,., ~113723 When the dial-out command is received Step SHl2 is per~ormed.
Step S~2 - Send number_out over link In this step the micro-processor ~M-C injects the di~lling information into the allocated communic~tion ch~nnel using the digital transmitter-receiver ~D~/R. ~his dialling information will be passed over the allocated commun'cation channel lnvolving the microwave link between the handset and the termi~al and step S~5 ~Fig. 5) will be ~ exited using the "yes" path.
i lO Step S 6 - Buffer dial information to network In this step the received dialling information is ¦ received by the micro-processor ~M-C from the allocated communication channel by wa~ o~ -the digital transmitter-receiver ~D?/R. As the dialling information is received 1 15 the micro-processor ~M-C converts that information into ~ suitable form for transmission to the telephone network ', a~d this converted information is passed over lead DI to the line interface equipment of the telephone network line corresponding to the allocated channel~ ~he terminal will circulate in steps ~6 and S~7 u~til the di311ing out over the line interface is complete. Eaving sent the dialli~g information out over the communication channel the handset performs step SHl3.
In this step the micro-processor ~M-C connects the digital transmitter receiver HD~/R through to the codec EC
thereb~ connecting the handset microphone ~M and receiver ; ~R through to the allocated communication chPnnel. At the ,. . ~ .
: . :, : ; ,.. ,. ,, . ~, :
: ,: - :
::
:
~L37~3~
_ 24 -same time the terminal will have completed its dialling-out operation entering step S~8 (~ig. 5).
Step S~8 - Establish Audio,_path In this step the micro-processor ~M-C will connect the allocated communication channel to the line interface ~I serving that telephone network termination taken into use by the micro-processor ~M-C to repeat the dialling information~ ~his.makes the "audio" path from the line inter~ace through to the handset microphone ~M and receiver ER. ~he terminal now returns -to a background program allowing other phone point calls to be serviced. ~he rest of the c 1-1 until it is termi~ated will be administered b~ the handset performing steps SHl4~16.
Ste ~
15 In this step the micro-processor H~-C will detect the set-up of the telephone call (i.e. when the called sub answers). ~his i9 used to start the accounting function for the caIl. ~ypicall~ the micro-processor EM-C in the handset knows the called ~umber and it knows the time oX day so it ca~ start mo~itoring the call loo~ing for a call term~nate co~dition to be able to calculate the cost of the call to be deleted from the credit store ECS. ~hese steps are shown i~ ~i30~. 4 at ~Hl4, SHl5, SHl6 and S~17.
~he micro-processor HM-C will record the time of day at which this occurs and wlth reference to the ~umber dialled, it can calculate the cost o~ the call in accordance with internall~ store call charges~ ~ call termination ma~ be ,::
~: :
3~
` . `
~ "~
~3~3~
-as a result o~ the Subscriber ~olding up his handset or operating the call terminate button or the keyboard HE.
Ste~ SH17 - Decrement credit store In this step the call cost calculated in steps SRn5 and 16,is decremented from the credit store ~C~. ~his terminates the operation of the phone point s~stem eauipment.
~he above description has been o~ one simple embodiment ,only and is not,intended to be limiting to the invention.
Many alternative arrangements can be envisaged by those skilled in the art, for example the above description has indicated that the credit store is decremented in accordance , with an internal calculation performed b~ the micro-processor of the handset. An alternative arrangement could be provided where the phone point terminal generates metering information ~` 15 which is communicated over the allocated communication channel to the handset. Further the flow diagram of ~igs~
4 ,and 5 are necessaril~ brief and many routes allowing for call abandonment have not been shown~ Purther to validate the phone point system an automatic interchange can be included in the initial p,hone point system call set-up procedure involving the ~ndset intarnal identity in~o~mation exchange and the checking of the handset internal cloc~/
date mechanism. ~inally the way the phone point terminal inter~aces to the telephone system obviously depends upon the telephone system involved. ~ypically one line interface may be provided for each netwGrk termination or a single termination may be time division multiplex shared by a number of phone point ch~nnels. Finally a "credit card"
~, :
~ ~137239 ~, s~stem co~d be u~ed in place of the credit store with the card number permanentl~ in the hand~et and with central call accounting performed using information on the call and credit card number located in the phone point terminal.
:
, :
~ . :
Claims (12)
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. A telecommunication system having a plurality of communication terminals connected in the network of the system, each communication terminal being arranged to co-operate with a plurality of portable communication units each of which is adapted to co-operate with any of the communication terminals to set-up telecommunication calls involving the network and the portable network communication unit to any termination on the network and each portable communication unit includes a call tariff credit charging arrangement adapted to be used to account for the usage of the portable communication unit on chargeable telecommuni-cation calls involving the network.
2. A telecommunication system having a plurality of subscribers terminals and a plurality of communication terminals connected to the network of the system, each communication terminal is arranged to co-operate with a plurality of portable communication units and each portable communication unit is adapted to co-operate with any of said communication terminals to set-up telecommunication calls involving the network and a portable communication unit to any of the subscribers terminals on the network and each portable communication unit includes means for coupling the portable communication unit to a communication terminal, means for transmitting telecommunication network control information and communication information to a communication terminal, means for receiving telecommunication information from a communication terminal and telecommunica-tions call tariff credit storage arrangements adapted to be decreased by the telecommunication call usage of the portable communication unit and each communication terminal includes means for interfacing the portable communication units with the telecommunications network including means for receiving tele-communications information from a portable communication unit and means for transmitting telecommunications information to a portable communication unit.
3. A telecommunication system according to claim 1 or claim 2 in which the portable communication units include a micro-processor and a telecommunication call tariff credit store and the micro-processor is arranged to destroy areas of the credit store in accordance with the usage of the portable communication unit on chargeable telecommunication calls.
4. A telecommunication system according to claim 1 or claim 2 in which the portable communication units include a micro-processor and a telecommunication call tariff credit store comprising a fusible link programmable read-only memory, and the micro-processor is arranged to destroy areas of the credit store in accordance with the usage of the portable communication unit on chargeable telecommunication calls.
5. A telecommunication system according to claim 1 or claim 2 in which the portable communication units include a micro-processor and a telecommunication call tariff credit store and the micro-processor is arranged to destroy areas of the credit store in accordance with the usage of the portable communication unit on chargeable telecommunication calls and in which the communication termi-nal includes means for communicating to the portable communication units network metering information which is used by the micro-processor in a portable communi-cation unit to compute a call tariff.
6. A telecommunication system according to claim 1 or claim 2 in which the portable communication units include a micro-processor and a telcommunication call tariff credit store comprising a fusible link programmable read-only memory and the micro-processor is arranged to destroy areas of the credit store in accordance with the usage of the portable communication unit on chargeable telecommunication calls, and in which the communication terminal includes means for communicating to the portable communication units network metering informa-tion which is used by the micro-processor in a portable communication unit to compute a call tariff.
7. A telecommunication system according to claim 1 or claim 2 in which the portable communication unit includes telecommunications communication informa-tion transmitter and receiver, a keyboard including a push-button dialling arrangement, a visual display device and a communication link interconnecting the portable communication unit with a communication terminal.
a. A telecommunication system according to claim 1 or claim 2 in which the portable communications unit includes telecommunications communication informa-tion transmitter and receiver, a keyboard including a push-button dialling arrangement, a visual display device and a two-way radio interconnecting the portable communication unit with a communication terminal.
9. A telecommunication system according to claim 1 or claim 2 in which the portable communications unit includes telecommunications communication informa-tion transmitter and receiver, a keyboard including a push-button dialling arrangement, a visual display device and a two-way radio operating at microwave frequencies and interconnecting the portable communication unit with a communication terminal.
10. A telecommunication system according to claim 1 or claim 2 in which the communication terminal includes a plurality of communication channels and a common control channel and the portable communication unit is arranged to use the common control channel to signal a demand to set-up a connection to the com-munication terminal and the communication terminal is arranged to allocate one of the communication channels to a calling portable communication unit.
11. A telecommunication system according to claim 1 or claim 2 in which the communication terminal includes a plurality of communication channels and a common control channel and the portable communication unit is arranged to use the common control channel to signal a demand to set-up a connection to the communication terminal and the communication terminal is arranged to allocate one of the communication channels to a calling portable communication unit, the communication link in the portable communication unit being arranged to adjust itself to a particular communication channel in accordance with information passed over the control channel from the communication terminal.
12. A telecommunication system according to claim 1 or claim 2 in which the communication terminal includes a plurality of communication channels and a common control channel and the portable communication unit is arranged to use the common control channel to signal a demand to set-up a connection to the communication terminal and the communication terminal is arranged to allocate one of the communication channels to a calling portable communication unit, said communication terminal including telecommunication message storage arrangements for storing messages for and from the portable communication units and the communication link in the portable communication unit being arranged to adjust itself to a particular communication channel in accordance with information passed over the control channel from the communication terminal.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB7922947 | 1979-07-02 | ||
| GB22947/79 | 1979-07-02 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1137239A true CA1137239A (en) | 1982-12-07 |
Family
ID=10506241
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000340664A Expired CA1137239A (en) | 1979-07-02 | 1979-11-26 | Telecommunications system incorporating portable communications units |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1137239A (en) |
-
1979
- 1979-11-26 CA CA000340664A patent/CA1137239A/en not_active Expired
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| MKEX | Expiry |