Abstract:
A method of setting security codes in a remote communicating device using a base unit in a cordless telephone system includes the steps of bringing the remote communicating device into electrical contact with the base unit, wherein the base unit stores a transmitting security code (TC) and a receiving security code (RC), different from the TC; determining whether the remote communicating device is either a remote receiving device (RRD), a remote transmitting device (RTD), or a remote combination transmitting/receiving device (RCD); setting the remote communicating device with the RC if the remote communicating device is the RRD, or the TC if the remote communicating device is the RTD, or both the RC and the TC if the remote communicating device is the RCD, as determined above, said setting done via the electrical contact with the base unit; and verifying the RC or TC or both the RC and the TC in the RRD, RTD, or RCD, respectively, as determined above, said verifying done via the electrical contact with the base unit. The RC is selectable at the base unit by a user, thereby setting the same selected RC each time the RRD or the RCD is set, and the TC is automatically randomized by the base unit, thereby setting a different TC each time the RTD or the RCD is set.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates generally to a cordless telephone system, and more particularly to a method of setting security codes in a cordless telephone system having one or more communicating devices. 
     2. Discussion of the Related Art 
     Cordless telephone systems generally include a base unit and a handset which communicate using Radio Frequency (RF) signals. The base unit is connected to a telephone network, such as the Public Switched Telephone Network (PSTN), while the handset can be removed from the base unit and used within a predetermined range, which is limited by the RF signal strength and not cord length. The transmission from the handset to the base unit is typically on a different frequency than the transmission from the base unit to the handset, providing duplex communications. 
     Existing cordless telephone systems offer additional conveniences over conventional corded phones, such as mobility, and currently a convenient method of transmitting the voice of a person or speaker, referred to hereinafter as a presenter, to a telephone network to conduct a clear telephone conversation in a conference room or auditorium setting is set forth in co-pending U.S. patent application Ser. No. 09/433,530 to Carley, filed on Nov. 4, 1999, which is incorporated herein by reference. Speakerphones may of course also be used for this purpose, however, speakerphones are often less than ideal because they restrict the movement of the presenter, who may not always want to stay near the speakerphone. In addition, speakerphones will often pick-up considerable background noise in a conference room or auditorium setting. 
     A presenter could carry a corded telephone handset or a cordless telephone handset to transmit the presenter&#39;s voice to a telephone network while moving around, but this is usually not practical because it substantially restricts the ability of the presenter to use his or her hands for other purposes. Additionally, the presenter&#39;s audience cannot hear the telephone conversation when a handset is used. 
     Where a sound system is being used to broadcast the presenter&#39;s speech, the system can, in theory, be connected to a telephone line, but this is often difficult, expensive or otherwise impractical. Also, a telephone jack may not be available in many auditoriums or conference rooms. 
     For all of the above reasons, cordless telephone systems with multiple transmitting and receiving communicating devices have been suggested. For example, a cordless telephone system may include as a transmitting device, a cordless microphone, and as receiving devices, cordless speakers, and as combination transmitting/receiving devices, a cordless headset and a sound system interface, all wishing to communicate with a common base station. In order to minimize the cost of such a cordless telephone system, each communication device is designed for relatively simple simplex RF communications. The combination transmitting/receiving devices can conceptually be treated as separate transmitting and receiving devices in one unit. Multiple receiving devices and only one transmitting device communicate with the base unit at a given time. 
     In maintaining a simpler, cost effective design, there is a need to synchronize the communication between multiple communicating devices and the base unit. Given the fixed amount of radio spectrum, only a relatively small portion has been allocated to cordless telephones. Cordless telephone systems operate on a selected band of a relatively few channels. The base unit and the communicating device are set to the same channel for communication. The likelihood is high that a particular location may be undesirably within the communication range of more than one cordless telephone user on the same channel. Given the relative density of urban and suburban areas, and the desirability of having a cordless phone system with sufficient communication range to allow its use within a reasonable proximity of the base unit, a number of cordless telephone users in a given neighborhood may find themselves causing RF interference with nearby cordless telephone systems. Given also the relatively small number of channels used for cordless telephones, it is also relatively simple for a person to select a channel on his cordless telephone which is the same as the channel of another user. 
     For these reasons, it is common to employ a security code in cordless telephone systems. Thus, in addition to selecting one of a relatively small number of channels, a cordless telephone user is able to establish a security code, much like a security code is established by persons utilizing remote control garage door openers on a common frequency. This technique guards, at least to a certain extent, against the possibility of unintentional or unauthorized access to a user&#39;s telephone conversation. 
     It is desirable to set the security code in the communicating devices by temporarily bringing them into contact with the base unit. U.S. Pat. No. 4,731,813 describes a cordless telephone system in which a single security code is communicated between the base unit and the handset by modulating the charging current supplied to the handset from the base unit. However, there are additional considerations where a cordless telephone system includes multiple communicating devices, since all receiving devices must be set to a receiving security code common with the base unit and only one transmitting device may contain the same transmitting security code, which is different from the receiving security code to prevent interference with the base unit. 
     Therefore, a need exists for a method of setting a transmitting security code and a receiving security code, different from the transmitting security code, in remote communicating devices in a low cost cordless telephone system with multiple remote communicating devices. 
     SUMMARY OF THE INVENTION 
     It is therefore an object of the present invention to provide a method of setting a transmitting security code and a receiving security code, different from the transmitting security code, in remote communicating devices in a low cost cordless telephone system with multiple remote communicating devices. 
     It is another object of the present invention to provide a method of setting a receiving security code in remote receiving devices in a low cost cordless telephone system with multiple remote communicating devices so some or all receiving devices may be set to the same receiving security code as the base unit. 
     It is still another object of the present invention to provide a method of setting a transmitting security code in remote transmitting devices in a low cost cordless telephone system with multiple remote communicating devices so only a selected one transmitting remote communicating device and the base unit are set to the same transmitting security code. 
     To achieve the above objects, a method of setting security codes in a remote communicating device using a base unit in a cordless telephone system in accordance with the present invention is provided which includes the steps of bringing the remote communicating device into electrical contact with the base unit, wherein the base unit stores a transmitting security code (TC) and a receiving security code (RC), different from the TC; determining whether the remote communicating device is either a remote receiving device (RRD), a remote transmitting device (RTD), or a remote combination transmitting/receiving device (RCD); setting the remote communicating device with the RC if the remote communicating device is a RRD, or the TC if the remote communicating device is the RTD, or both the RC and the TC if the remote communicating device is the RCD, as determined above, said setting done via the electrical contact with the base unit; and verifying the RC or TC or both the RC and the TC in the RRD, RTD, or RCD, respectively, as determined above, said verifying done via the electrical contact with the base unit. 
     The RC is selectable at the base unit by a user, thereby setting the same selected RC each time the RRD or the RCD is set, and the TC is automatically randomized by the base unit, thereby setting a different TC each time the RTD or the RCD is set. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The above and other objects, features and advantages of the present invention will become more apparent in light of the following detailed description of an exemplary embodiment thereof taken in conjunction with the attached drawings in which: 
     FIG. 1 illustrates a cordless telephone system which uses a method of setting security codes in accordance with the present invention; 
     FIG. 2 illustrates a base unit and remote communicating device for having means for setting security codes in accordance with the method of the present invention; and 
     FIG. 3 is a flow chart illustrating a method of setting security codes in the remote communicating devices of the cordless telephone system of FIG. 1 in accordance with an embodiment of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Turning now to the drawings, in which like reference numerals identify similar or identical elements throughout the several views, FIG. 1 illustrates a cordless telephone system  10  comprising a microphone  12 , transmitter  14 , and base unit  16 . System  10  may include a cordless speaker  20 , sound system interface unit (SSUI)  30 , handheld/standheld cordless microphone  11  and cordless headset  13  that may optionally be used in system  10 , and a telephone jack  22  for connecting base unit  16  to a telephone network, such as the PSTN. Generally, microphone  12  is adapted to be worn by an individual or, more clearly, a presenter, such as a lapel type microphone, and is used to receive acoustical signals from the presenter and to convert the acoustical signals to corresponding electrical audio signals. The transmitter  14  is also adapted to be worn by the presenter and is electrically connected to the microphone  12  via wire to receive the electrical audio signals, to convert the electrical audio signals to RF signals, and to transmit the RF signals. Similarly, a handheld or standheld cordless microphone  11  may also be used, with an integrated transmitter in the body of the microphone. 
     The base unit  16  is remote from the microphone  12  and the transmitter  14 ; that is, the base unit  16  is not physically connected to either the microphone  12  or the transmitter  14 . The base unit  16  receives the RF signals from the transmitter  14  on a receiving frequency and converts the RF signals to telephone network electrical signals corresponding to the acoustical signals from the presenter. Also, the base unit  16  is connected to a telephone network via the telephone jack  22  to transmit the telephone network signals to the network and to receive telephone network signals from the network that correspond to other audible telephone communications. The base unit  16  optionally includes a built in speaker to broadcast the telephone conversation. 
     The cordless speaker  20  is remote from the base unit  16 , microphone  12  and transmitter  14 . When the cordless speaker  20  is used in system  10 , the base unit  16  must include a base unit transmitter, similar to the transmitter  14  for the microphone to transmit RF signals on a transmit frequency, different from the receive frequency, to the cordless speaker. The telephone base unit transmitter transmits RF signals representing the telephone communications received by the telephone base unit  16  from the telephone network and also, optionally, the RF signals corresponding to the acoustical signals received from the presenter. The cordless speaker  20  converts the received RF signals into electrical audio signals to broadcast them over the speaker. Additionally, the cordless speaker  20  includes an ‘audio out’ jack to facilitate connection to a conventional sound system ‘line in’ jack via a cable, thereby providing corresponding electrical audio signals to the sound system as well and allowing the telephone conversation to be heard over the sound system throughout a larger area. 
     The base unit  16  may be a typical cordless telephone base, preferably with speakerphone capabilities. However, in lieu of the cordless handset, the base unit  16  receives signals from the cordless microphone  12 , via transmitter  14 , or microphone  11 , via its built-in transmitter. Also, optionally, the base unit  16  may include a base unit transmitter to transmit RF signals to one or more cordless speakers  20 . The base unit  16  is connected to an AC power source, and is connected to a telephone network via jack  22 . In use, the signals received from the cordless microphone  12  are ultimately transmitted to the telephone network, and the signals received on the telephone network are ultimately reproduced as audio on the speaker in the base unit  16  and/or one or more cordless speakers  20 . 
     The base unit  16  may also be provided with many features commonly known in the art. For example, preferably, the speaker on the base unit  16  can be muted and can also be used for initiating and receiving telephone calls, where a numeric keypad is provided. Further, the base unit  16  may also include ‘audio out’ connections for connection to a ‘line in’ jack of a conventional sound system, thereby providing corresponding electrical audio signals to the sound system as well and allowing the telephone conversation to be heard over the sound system throughout a larger area. 
     The base unit  16  receives RF signals from transmitter  14  in a user selectable one of a plurality of predetermined frequency channels, and the transmitter  14  is designed to transmit RF signals in a selected one of the predetermined frequency channels using a common transmit security code. Additionally, the transmitter  14  transmits the RF signal to the base unit  16  on a receive frequency of the base unit  16  and is a simplex remote communicating device. Only one transmitter  14  is used within the cordless telephone system to avoid interference between received signals at the base unit  16 . This is controlled by setting only a selected one transmitting device for synchronization with the base unit  16 . 
     The cordless speaker  20  includes a receiver to receive the RF signals from the base unit  16 , and a speaker and amplifier with a volume control. Cordless speaker  20  may also be provided with jacks for connection to a sound system as described above. The cordless speaker  20  is a simplex remote communicating device which receives the RF signals from the base unit  16  on a transmit frequency of the base unit  16 . Unlike the microphone transmitter  14  or handheld/standheld cordless microphone  11 , multiple cordless speakers may be used simultaneously on the cordless phone system, all set to the same channel of the base unit  16  and the same receive security code, without fear of interference. 
     The SSIU  30  provides duplex communications between the base unit  16  and a sound system  31 . The SSIU  30  includes ‘audio out’ and ‘audio in’ jacks which connect via cables to a sound system&#39;s ‘line in’ and ‘line out’ jacks respectively. The sound system&#39;s microphone(s) and speaker(s) then become part of the cordless telephone system, substituting for the microphones and speakers in the cordless system with the SSIU  30  transmitting and receiving RF signals to and from the base unit  16  accordingly. The SSIU 30  transmits and receives the RF signals on separate channels using separate security codes corresponding to a receive and transmit channel of the base unit  16 . The base unit  16  may also optionally include ‘audio out’ and ‘audio in’ jacks for direct connection to the sound system  31  from the base unit  16 . 
     A cordless headset  13 , including a microphone and ear phone, is also a duplex remote communicating device. The cordless headset  13  is electrically connected to a transceiver  15  and includes a microphone to convert received acoustical signals to corresponding electrical audio signals. The transceiver  15  is adapted to be worn by the presenter and receives the electrical audio signals and converts the electrical audio signals to RF signals and transmits the RF signals to the base unit  16 . The transceiver  15  also receives RF signals from the base unit  16 , and converts them to electrical audio signals for broadcasting by the earphones in the cordless headset  13 . The transceiver transmits and receives the RF signals on separate channels using separate security codes corresponding to a receive and transmit channel of the base unit  16 . The transceiver  15  may also optionally include a keypad  15   a  to facilitate call setup functions on the base unit  16  from a remote location. 
     The system illustrated above is subject to the limitation of supporting a maximum of one transmitting remote communicating device, such as a cordless microphone  11 ,  12 , cordless headset  13  (microphone portion), and SSIU  30  (‘audio in’ portion), while supporting multiple receiving remote communicating devices, such as cordless speakers  20 , cordless headset  13  (earphone portion), and SSIU  30  (‘audio out’ portion). 
     The cordless telephone system of FIG. 1 provides low cost simplex communications between the base unit  16  and a number of specialized remote communicating devices. Even the duplex devices are a combination of a specialized transmitting remote communicating device with a specialized receiving remote communicating device. The receiving remote communicating devices must be set to the same receiving security code as the base unit  16  and only one transmitting remote communicating device may be set to the same transmitting security code as the base unit  16 , to prevent interference. 
     FIG. 2 illustrates a base unit  16  and remote communicating device  200  using a method of setting security codes in accordance with the present invention. Referring to FIG. 2, a remote communicating device  200  represents any one of the remote communicating devices shown in FIG. 1, namely the microphone  11 , transmitter  14  for microphone  12 , cordless speaker  20 , SSUI  30 , handheld/standheld cordless microphone  11 , or transceiver  15  for cordless headset  13 . The base unit  16  includes contacts  210   a  which correspond to contacts  210   b  on the remote communicating device  200 . The security code setting procedure executes when the remote unit  200  physically contacts the base unit  16 ; more specifically, when the remote communicating device&#39;s contacts  210   b  are electrically connected to the base unit&#39;s contacts  210   a . The security code data is transmitted from the base unit  16  to the remote communicating device  200  via the corresponding contacts  210   a ,  210   b.    
     The remote communicating device  200  is properly aligned with the base unit  16  via mating supporting structures. For example, the base unit  16  may include a horseshoe shaped raised supporting member  220   a  on its top which aligns with a corresponding horseshoe shaped inset  220   b  on one side of the remote communicating device  200 , such that when the remote communicating device  200  is inserted onto the base unit  16 , the corresponding contacts  210   a ,  210   b  are aligned and therefore electrically connected. Many other supporting structures may be contemplated, serving the same function. 
     The base unit  16  may also include a keypad  230  with an optional reset button  240  and may include a reset key switch  250  which accepts a key for added security. The reset button  240  or the reset key switch  250  serves to increment or randomize the receiving security code in the base unit  16 . That is, the security code that is commonly used by all receiving remote communicating devices, such as the cordless speakers  20 , transceiver  15  for cordless headset  13  (earphone portion), and SSIU  30  (‘audio out’ portion), and the base unit  16  is changed by a user only by pressing the reset button  240  or turning the reset key switch  250 . The receiving security code may also optionally be changed by the user via the keypad  230  after entering an access code. The transmitting security code is randomized and set automatically by the base unit  16 , as described further below. 
     FIG. 3 is a flow chart illustrating a method of setting security codes in the remote communicating devices of the cordless telephone system of FIG. 1 in accordance with an embodiment of the present invention. Referring to FIG. 3, a method of setting security codes in a cordless telephone system includes selecting a new receiving security code at the base unit  16  in step  300 . As described above, the reset button  240  or the reset key switch  250  serves to increment or randomize the receiving security code in the base unit  16 . That is, the security code that is commonly used by all receiving remote communicating devices, such as the cordless speakers  20 , transceiver  15  for cordless headset  13  (earphone portion), and SSIU  30  (‘audio out’ portion), and the base unit  16 , is changed only by a user by pressing the reset button  240  or turning the reset key switch  250 . The receiving security code may also optionally be changed by the user via the optional keypad  230  after entering an access code. The user may also choose to use the receiving security code currently set in the base unit  16 , eliminating step  300 . 
     In step  305 , the base unit  16  determines when a remote communicating device  200  is positioned onto the base unit  16 , that is, whether the remote communicating device&#39;s contacts  210   b  are in electrical contact with the base unit&#39;s contacts  210   a . This may be determined by periodically polling, for instance once a second, the base unit&#39;s contacts  210   a for the presence of a remote communicating device  200  and awaiting a response to the polling from the remote communicating device  200 . Another possible method is to detect a change in current between the base unit&#39;s contacts  210   a  when the remote communicating device  200  is positioned onto the base unit  16 . 
     In any case, once the presence of remote communicating device  200  is detected, the base unit  16  next determines at step  310  if the remote communicating device  200  is, partially or wholly, a receiving device using, for example, the polling or current sensing method above. That is, whether the remote communicating device  200  performs receiving functions, such as the cordless speakers  20 , transceiver  15  for cordless headset  13  (earphone portion), and SSIU  30  (‘audio out’ portion), and the base unit  16 , and therefore requires a receiving security code. If the base unit  16  determines the remote communicating device  200  is a receiving device in step  310 , the base unit  16  next compares the current base unit receiving security code to the receiving security code currently set in the remote communicating device  200 , in step  315 . If the base unit  16  determines the current base unit receiving security code is the same as the receiving security code currently set in the remote communicating device  200 , the base unit  16  notifies the user that the current receiving security code is set via an audible or visual notification in step  320 . A small speaker, light emitting diode (LED), or liquid crystal display (LCD) may be included in the base unit  16  for this purpose. If instead, in step  315 , the base unit  16  determines the current base unit receiving security code differs from the receiving security code currently set in the remote communicating device  200 , the base unit  16  communicates the new receiving security code to the remote communicating device  200  via the corresponding contacts  210   a and  210   b , in step  325 . The base unit  16  then again compares the current base unit receiving security code to the receiving security code currently set in the remote communicating device  200  for verification purposes by returning to step  315 , and upon verification, to step  320  to notify the user that the current receiving security code is set. This procedure continues until the codes are determined to be the same in step  325  or a maximum number of retries have been exceeded in step  326 . If the maximum number of retries, for instance three, have been exceeded in step  326 , the base unit  16  notifies the user an error has occurred in step  360 , again using an LED, LCD or speaker, and the procedure ends. 
     However, if in step  310  the base unit  16  determines the remote communicating device  200  is not a receiving device or after notifying the user that the current receiving security code is set in step  320 , the base unit  16  next determines whether the remote communicating device  200  is a transmitting device in step  330 . This determination is made by the base unit  16  by again using, for example, the polling or current sensing method above. However, here the result returned by the transmitting remote communicating device  200  differs from the result returned by the receiving remote communicating device  200  so the base unit  16  may properly differentiate the two. That is, the base unit  16  determines if the remote communicating device  200  is, partially or wholly, a transmitting device performing transmitting functions, such as a cordless microphone  11 , transmitter  14  for microphone  12 , transceiver  15  for cordless headset  13  (microphone portion), and SSIU  30  (‘audio in’ portion), and therefore requires a transmitting security code. 
     If the base unit  16  determines the remote communicating device  200  is a transmitting device in step  330 , the base unit  16  next randomly selects a new active transmitting security code from a list of possible security codes stored in the base unit  16 , in step  335 . This randomization of the transmitting security code helps insure that no two transmitting remote communicating devices are transmitting using the same security code simultaneously, enabling only one transmitting device to transmit and thereby eliminating possible interference. Next, the base unit  16  communicates the new active transmitting security code to the transmitting remote communicating device  200  via the corresponding contacts  210   a and  210   b , in step  340 . If, in step  345 , the base unit  16  then verifies the current base unit transmitting security code is the same as the transmitting security code currently set in the remote communicating device  200 , the base unit  16  notifies the user that the current transmitter security code is set via an audible or visual notification in step  350 . A small speaker, LED, or LCD may be included in the base unit  16  for this purpose. 
     If instead, in step  345 , the base unit  16  determines the current base unit transmitting security code differs from the transmitting security code currently set in the remote communicating device  200 , the base unit  16  again communicates the new active transmitting security code to the remote communicating device  200  via the corresponding contacts  210   a  and  210   b , returning to step  340 . The base unit  16  then again compares the current base unit transmitting security code to the transmitting security code currently set in the remote communicating device  200  for verification purposes in step  345 . This procedure continues until the codes are determined to be the same in step  345  or a maximum number of retries has been exceeded in step  346 . If the maximum number of retries, for instance three, has been exceeded in step  346 , the base unit  16  notifies the user an error has occurred in step  360 , again using an LED, LCD or speaker, and the procedure ends. Otherwise, after notifying the user that the current transmitter security code is set via an audible or visual notification in step  350 , the user is further notified that the procedure has been completed in step  355  and the procedure ends. 
     However, if in step  330  the base unit  16  determines the remote communicating device  200  is not a transmitting device, the user is notified that the procedure has been completed in step  355  and the procedure ends. 
     Here, it is also important to note that certain devices contain both receiving and transmitting portions, such as the SSIU  30  and the transceiver  15  for the cordless headset  13 , and would therefore have both the transmitting and receiving security codes updated in one operation, performing all the steps of FIG.  3 . However, where a user wishes to only set the transmitting security code in the SSIU  30  or transceiver  15  for the cordless headset  13 , he or she merely skips step  300 , thereby leaving the current common receiving security code setting in the SSIU  30  or transceiver  15  for cordless headset  13 . Alternatively, where a user wishes to only set the receiving security code in the SSIU  30  or transceiver  15  for cordless headset  13 , he or she subsequently inserts the desired active transmitting device, thereby assigning the current transmitting security code to the desired active transmitting device only in lieu of the SSIU  30  or transceiver  15  for the cordless headset  13 . 
     Additionally, it is important to note that while the method of the present invention has been discussed in conjunction with the cordless telephone system of FIG. 1, the method of the present invention is contemplated to be used with any number of similar communication systems. Further, while the present invention has been described in detail with reference to the preferred embodiments, they represent mere exemplary applications. Thus, it is to be clearly understood that many variations can be made by anyone of ordinary skill in the art while staying within the scope and spirit of the present invention as defined by the appended claims.