CA2075257C - Wireless telephone with frequency inversion scrambling - Google Patents
Wireless telephone with frequency inversion scramblingInfo
- Publication number
- CA2075257C CA2075257C CA002075257A CA2075257A CA2075257C CA 2075257 C CA2075257 C CA 2075257C CA 002075257 A CA002075257 A CA 002075257A CA 2075257 A CA2075257 A CA 2075257A CA 2075257 C CA2075257 C CA 2075257C
- Authority
- CA
- Canada
- Prior art keywords
- base unit
- voice signals
- remote unit
- unit
- remote
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
Classifications
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04K—SECRET COMMUNICATION; JAMMING OF COMMUNICATION
- H04K1/00—Secret communication
- H04K1/04—Secret communication by frequency scrambling, i.e. by transposing or inverting parts of the frequency band or by inverting the whole band
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04M—TELEPHONIC COMMUNICATION
- H04M1/00—Substation equipment, e.g. for use by subscribers
- H04M1/72—Mobile telephones; Cordless telephones, i.e. devices for establishing wireless links to base stations without route selection
- H04M1/725—Cordless telephones
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- Engineering & Computer Science (AREA)
- Computer Networks & Wireless Communication (AREA)
- Signal Processing (AREA)
- Mobile Radio Communication Systems (AREA)
Abstract
The wireless telephone of the present invention is comprised of a base unit, coupled to a land-line telephone system, and a remote unit that communicates with the base unit over radio frequencies. The remote unit has scrambling circuits (207 and 216) for encrypting voice signals transmitted to the base unit and decrypting voice signals received from the base unit. The base unit also has scrambling circuits (107 and 116) for encrypting voice signals transmitted the remote unit and decrypting voice signals received from the remote unit.
The wireless telephone uses a keypad (222) for initiating a demonstration mode that allows both parties to the conversation to hear the scrambled voice signal.
The wireless telephone uses a keypad (222) for initiating a demonstration mode that allows both parties to the conversation to hear the scrambled voice signal.
Description
2~7~257 WT~.T.F'.~S~ TELEPHONE WITH FPU3QUENCY INYERSION
SCRAMBLING
~Fieldl ~~1~ ~L~
s The prssent invention relates generally to the field of co~nunic~tions and particularly to signal scr~n hlin~ be-tween a base and remote wireless telephone.
~ ~~e ~
Cordle~s or wirele~s teleplhones are typically honne units that consist of a base unit and one or more remote u~:it~.
An example of such a cordless telephsrle i~ seen in U.S.
15 Patent No. 4,989,230 to Gillig et al., ~signe~l to Motorola, Inc., and is incorporated her~ain by reference. ~he remote units com m~nic~te with ~he base uLnit over radio fi~eque~cies (R F) t31pica~1y within a r ~ ge of1nOO ~eet of~he base ~ t. Ilhe base UY~t is connect~d to the la~nd-line telsphone sys~e mgthu~ al-2 0 lowi~g a renno~e user to Gom mllnicate v~i~h o~her land-line telephones.
l~he proble m ~nth ~his t ~ e ofsyste m, however~is that the RF si~al8 CaIl be received by anyone with a receiver tuuled to the freqllency being used by the cordless telephone. Thi~
S ma~kes it dif~cult to have a private co~,v~lsation using a cord-les~ telephone. Cordless telephones that scra m ble the ~UF
Yoice sigpnal don't provnde for tes~ing the scr~ m hli~ filn~t;on tD d~elfuu5.e if it is working properly. There is a resulting need for 2 cordless telephone that makes it difficult iEor the 3 0 voice ~ignals to be li~tened to and also enable the scr2mhlinE
f~mction t,o be checked for proper operation.
~~r.~ oiE~heInve~
3 S The wireless commun:icatio~ system of the present in-vention i~ cornprised of a base ~Ulit, coupled to a land-line tele-~ 2~75~
phone ~ystem, and a remote unit that commurlicateq with the ba~e unit over radio ~rsquencies. The remote unit is com-prised of encryption means, located in the transmit path of the remote unit, ~~r encryp~ing voice 6ignaL19 transmitted to the S base unit and deQtion mearls, located in a receive pa~ of t~e remote ur~it, ~or decrypting voice si~als receiYed :from the base unit. The base unit is comprised of encryptioIl m~ s, located in a trans~it path of the base unit, for encrypting ~,roice Sig~ S transmitted to the remote unit and decryption means, 1 0 located in a receive path of the base unit, for de~;.y~ g voice signals rece*ed ~om the remote unit. The wireless commu-nic~tion sys~em has control e~try means, located in the re-mote ur~it, for generating a control signal to disable the de-cryption means in the remote and base ~ts.
. 15 B~ Lio~theI~
FIG. 1 shows a block diagram of a base unit of the pre-~ent iIlverltion.
2 0 FIG. 2 shows a block diagram of a remote unit of the present invention.
FIG. 3 shows a ilowchart of the process of the present invention.
FIG. 4 ~hows a block diagram of the scrambler inte-2 5 grated circuit.
~t~ 1~ 1 O oil~ ~he P~ ~r~ 5 ~~ f ~ ~
The wireless telephone of the present ;nvention uses 3 0 scrambled RF ~roice signals to c-~mrnnnicate between the bas2 unit and the remote un~t. By ~is~hlin~ some of the scr~rnhlimg circuits ill the remote or both the remote and the base, bo~
paIties to the telephone call can determine that the scram-bling function is operational.
3 5 The block diagram of FIG. 1 illustrates a pre~erred em-bodiment of a cordless telephone base unit having a control-2~7~7 crypting sign~l~. This particular base unit also includes a speal~erphone FIG. 2 illus~rates a preferred embodiment of a remote unit for communicating with the base unit, the remote also having a controllable scrambling or encryption CilCUit for encrypting and decrypting cign~ls Referring to FIG. 1, the bas~ unit is comprised of an an-tenna (101) that is coupled to the receive and transmit paths of the base. The receive path is compnsed of a b~dp~s6 filter t102) that allows the frequencies of 4g.670 - 49.990 ~Iz to pass.
The filter i5 connected to a receive amplifi~3r (103~ that ampli-fies the ~ltered signal by appro~mately 18 dB. The output of the amplifier is then filtered by another bandpass filter (10~l) ~e~re being input to the receiver (105). In the pre~erred em-bodiment, the receiver is an MC3363 available from Motorola, Inc.
The receiver (1n5~ mixes ths signal down to 10.7 ~Iz and then to 455 kHz. This signal is then demodulated. The lo-cal oscillators in the receiver (105) are controlled by a phase locked loop (120~ whose ~requency is controlled by a micropro-~0 cessor (112). The microprocessor (112) also receives a carrier de~ect signal, labeled RSSI in ~IG. 1, and the demodulated signal from the receiver (105), labeled R~ D~a. The demodulated signal is used by the microprocessor (112) to interpret coded data messages transmitted by the remote un~t.
These coded data mes6ages are used for DTMF dialing, telephone hook switch control, and control of the scr~mhlin~
circuit. The carrier detect signal is used to detect the presence of a transmitter occupying the base unit rsceive (~h~nnçl In the pre~erred embodiment, ths microprocessor l112) is an MC68HCL05C4 available from Motorola, Inc.
The output of the receiver (105) is filtered agai~ by ~-other bandpass ~lter (106). The output of the filter (106) is in-put to the scrambling circuit (107). In the preferred emhodi-ment, the scrambling circuit (107) is an MX108DW Full-Duplex Voiceband Scrambler integrated circuit available from MX ~ Com, Inc.
~7~2~7 The unscrambled output of the scrambler circuit (107) is filtered in a de-emphasis filter (108) before being input to an expander (109). The expansion process applies gain to the in-put signal that is varied as a function of the signal magnitude.
The ef~ective gain being greater for large magnitude signals and less for small magnitude si~n~ls. After this si~nal has been lSltered by a highpass filter (110), it is input to a speaker-phone circuit (111~ and is also output to the land-line telephone system. If the speakerphone is being used, such as in a three 10 way call between the base, the remote, and a land-line party, the audio signal i~ output to the base UIlit'S speaker.
The transmit path of the base is comprised of the audio signal, either from the microphone (121) of the speakerphone or the land-line party, being bandpass filtered (113) before go 15 ing through a compressor (114). The compressor (114) applies gain to the audio signal that is varied as a function of the sig-nal magnitllde, the ef~ective gain being greater for small sig-nals. An ex~mple of a compandor (compressor/expander) is MC33110 manufactured by Motorola, Inc. The dynamic range ~0 of the compandor is 80 dB.
The output of the compressor (114) is input to a pre-em-phasis filter (115) before being scr~mhle~ by the scrambler cir-cuit (116). The scrambler circuit (116) is the second half of the same integrated (,ircuit used to unscramble the received sig-25 nal. The serambled audio signal is bandpass filtered (117) be-fore being rnodulated by the transmitter (118) to a ~requency in the range of'46.610 - 46.970 MHz. The actual ~requency used by the telephone can be user selectable by a switch or other con-trol on the telephone base or remote. Both the receive and 30 transmit frequency ranges are set by the FCC for all cordless telephones. An example of a transmitter is MC2833 manufac-hlred by Motorola, Inc.
The output of the transmitter is bandpass filtered t119) to filter out the signal outside the 46.B10 - 46.970 MHz range.
35 This signal is then transmitted from the antenna (101) to the remote unit.
2~2~7 The remote unit is comprised of the s~ntenn~ (201) that receives the signal Çrom the base unit. A bandpass filter (202) removes that part of the signal outside the range of 46.610 -46.97û MHz. A gain of approximately 18 dB is then applied to 5 the signal by a receive ampli~ler (203) before it is bandpass f;l-tered (204) again. This signal is then input to the recelver (205).
The remote unit receiver (205) mixes the signal down to 10.7 MHz and then to 45~ kHz. This signal is then demodu-10 lated. The demodulated signal, labeled RX Data, is input tothe microproces50r (212) to interpret the coded data ~ness~es transrnitted by the base unit. These coded data messages are used to control the remote ringer and the scrambling circuit.
The demodulated signal is also bandpass filtered (206) l5 before being input to the scrambler circuit (207) for descram-bling. The scrambler circuit (207) is identical to the integrated circuit used in the base unit.
The unscrambled output is filtered by a de-emphasis fil-ter (20~) before going through an expander (209). The ex-~D panded signal is bandpass ~Itered (210) and amplified (211).The amplifier (211) is controlled by the microprocessor (212).
By operating a control cn the remote unit, the user can in-crease or decrease the speaker (220) volume by increasing or decreasing the gain applied to the signal at this point. The 25 amplified signal is input to the earpiece speaker of the remote unit.
The microphone (221) of the remote generates the audio signal that is bandpass filtered (213), compressed (214), and filtered by a pre-emphasis filter (215) before being processed by 30 the scrambler circuit (216). This circuit (~16) is the seeond half of the integrated circuit used to unscramble the received signal.
The scrambled signal is bandpass ~ltered (217) before being modulated to a frequency in the range oii 49.67 - 49.99 35 MHz by the transmitter (218). The modulated signal is band-2~7~257 ~6-pass filtered ~219) to remove the signal outside this frequency range and is transmitted on the remote's antem~a (201).
I~e keypad on the remote (22~) is used to take the tele-phone off hook, enter telephone numbers, chan~e the fre-quency used to cornmunicate with the base, and to enable the scramble demonstration fimction. The keylpad enables the scr~mhling demonstration function by telling the micropro-cessor to generate a control signal to the scr~mhling inte-grated circuit. In the preferred emboAim~nt, the base unit 10 also has a keypad.
The control signals in both the remote and the base units are connected to the transmitter after the scrs~rnhling function so that these signals are not scrambled. The controi signals, generated by the microprocessor, are wire-OiRed wi.th 15 the scrambled voice signal to the transmitter input.
The scrambling of the signal between the remote and the base is operating continuously. This scrslnnhling, how-ever, is not evident to the telephone user or the party on the other end of the call. It would not be known, therefore, if the ~0 scrambling was operating properly. The scram~ling demon-stration process of the present invention provides both parties to the telephone call the ability to hear ~he scrambled version of the signal.
The scrambling demonstration process is illustrated in 25 FIG. 3. While the telephone is in a call, the keypad is scanned (301) by the microprocessor for the depression of a key, such as a Secure Demo key, that indicates that the remote unit user w~shes to enter the scrambling demonstratioIl mode. In the preferred embodiment, this mode is referred to as the Secure 30 Demo mode.
If the key i6 depressed (302), a timer in the microproces-sor i9 started (303). If the key is released immediately (304), the timer is cleared (305) and the keypad scanned again (301).
If the key is still depressed (304), the timer is incremented 35 (306) and checked to determine if the key has been depressed for at least 3 seconds (307). This time check is comtinued until 2~7~25~
the key has been depressed for 3 seconds. At this point, the scrambling demonstration mocle is operating (304). Thi~ ca be indicated on the remote or the base by fl~hinE inrlic~qtor lights (309). The remote keypad may be used -~or the a~ove pro-5 cess or, if the base has a keypad, this keypad may be used toenter the scrambling demonstration mode.
The block diagram of the MX108DW Full-Duplex Voiceband Scrambler integrated circuit is illustrated in FIG.
SCRAMBLING
~Fieldl ~~1~ ~L~
s The prssent invention relates generally to the field of co~nunic~tions and particularly to signal scr~n hlin~ be-tween a base and remote wireless telephone.
~ ~~e ~
Cordle~s or wirele~s teleplhones are typically honne units that consist of a base unit and one or more remote u~:it~.
An example of such a cordless telephsrle i~ seen in U.S.
15 Patent No. 4,989,230 to Gillig et al., ~signe~l to Motorola, Inc., and is incorporated her~ain by reference. ~he remote units com m~nic~te with ~he base uLnit over radio fi~eque~cies (R F) t31pica~1y within a r ~ ge of1nOO ~eet of~he base ~ t. Ilhe base UY~t is connect~d to the la~nd-line telsphone sys~e mgthu~ al-2 0 lowi~g a renno~e user to Gom mllnicate v~i~h o~her land-line telephones.
l~he proble m ~nth ~his t ~ e ofsyste m, however~is that the RF si~al8 CaIl be received by anyone with a receiver tuuled to the freqllency being used by the cordless telephone. Thi~
S ma~kes it dif~cult to have a private co~,v~lsation using a cord-les~ telephone. Cordless telephones that scra m ble the ~UF
Yoice sigpnal don't provnde for tes~ing the scr~ m hli~ filn~t;on tD d~elfuu5.e if it is working properly. There is a resulting need for 2 cordless telephone that makes it difficult iEor the 3 0 voice ~ignals to be li~tened to and also enable the scr2mhlinE
f~mction t,o be checked for proper operation.
~~r.~ oiE~heInve~
3 S The wireless commun:icatio~ system of the present in-vention i~ cornprised of a base ~Ulit, coupled to a land-line tele-~ 2~75~
phone ~ystem, and a remote unit that commurlicateq with the ba~e unit over radio ~rsquencies. The remote unit is com-prised of encryption means, located in the transmit path of the remote unit, ~~r encryp~ing voice 6ignaL19 transmitted to the S base unit and deQtion mearls, located in a receive pa~ of t~e remote ur~it, ~or decrypting voice si~als receiYed :from the base unit. The base unit is comprised of encryptioIl m~ s, located in a trans~it path of the base unit, for encrypting ~,roice Sig~ S transmitted to the remote unit and decryption means, 1 0 located in a receive path of the base unit, for de~;.y~ g voice signals rece*ed ~om the remote unit. The wireless commu-nic~tion sys~em has control e~try means, located in the re-mote ur~it, for generating a control signal to disable the de-cryption means in the remote and base ~ts.
. 15 B~ Lio~theI~
FIG. 1 shows a block diagram of a base unit of the pre-~ent iIlverltion.
2 0 FIG. 2 shows a block diagram of a remote unit of the present invention.
FIG. 3 shows a ilowchart of the process of the present invention.
FIG. 4 ~hows a block diagram of the scrambler inte-2 5 grated circuit.
~t~ 1~ 1 O oil~ ~he P~ ~r~ 5 ~~ f ~ ~
The wireless telephone of the present ;nvention uses 3 0 scrambled RF ~roice signals to c-~mrnnnicate between the bas2 unit and the remote un~t. By ~is~hlin~ some of the scr~rnhlimg circuits ill the remote or both the remote and the base, bo~
paIties to the telephone call can determine that the scram-bling function is operational.
3 5 The block diagram of FIG. 1 illustrates a pre~erred em-bodiment of a cordless telephone base unit having a control-2~7~7 crypting sign~l~. This particular base unit also includes a speal~erphone FIG. 2 illus~rates a preferred embodiment of a remote unit for communicating with the base unit, the remote also having a controllable scrambling or encryption CilCUit for encrypting and decrypting cign~ls Referring to FIG. 1, the bas~ unit is comprised of an an-tenna (101) that is coupled to the receive and transmit paths of the base. The receive path is compnsed of a b~dp~s6 filter t102) that allows the frequencies of 4g.670 - 49.990 ~Iz to pass.
The filter i5 connected to a receive amplifi~3r (103~ that ampli-fies the ~ltered signal by appro~mately 18 dB. The output of the amplifier is then filtered by another bandpass filter (10~l) ~e~re being input to the receiver (105). In the pre~erred em-bodiment, the receiver is an MC3363 available from Motorola, Inc.
The receiver (1n5~ mixes ths signal down to 10.7 ~Iz and then to 455 kHz. This signal is then demodulated. The lo-cal oscillators in the receiver (105) are controlled by a phase locked loop (120~ whose ~requency is controlled by a micropro-~0 cessor (112). The microprocessor (112) also receives a carrier de~ect signal, labeled RSSI in ~IG. 1, and the demodulated signal from the receiver (105), labeled R~ D~a. The demodulated signal is used by the microprocessor (112) to interpret coded data messages transmitted by the remote un~t.
These coded data mes6ages are used for DTMF dialing, telephone hook switch control, and control of the scr~mhlin~
circuit. The carrier detect signal is used to detect the presence of a transmitter occupying the base unit rsceive (~h~nnçl In the pre~erred embodiment, ths microprocessor l112) is an MC68HCL05C4 available from Motorola, Inc.
The output of the receiver (105) is filtered agai~ by ~-other bandpass ~lter (106). The output of the filter (106) is in-put to the scrambling circuit (107). In the preferred emhodi-ment, the scrambling circuit (107) is an MX108DW Full-Duplex Voiceband Scrambler integrated circuit available from MX ~ Com, Inc.
~7~2~7 The unscrambled output of the scrambler circuit (107) is filtered in a de-emphasis filter (108) before being input to an expander (109). The expansion process applies gain to the in-put signal that is varied as a function of the signal magnitude.
The ef~ective gain being greater for large magnitude signals and less for small magnitude si~n~ls. After this si~nal has been lSltered by a highpass filter (110), it is input to a speaker-phone circuit (111~ and is also output to the land-line telephone system. If the speakerphone is being used, such as in a three 10 way call between the base, the remote, and a land-line party, the audio signal i~ output to the base UIlit'S speaker.
The transmit path of the base is comprised of the audio signal, either from the microphone (121) of the speakerphone or the land-line party, being bandpass filtered (113) before go 15 ing through a compressor (114). The compressor (114) applies gain to the audio signal that is varied as a function of the sig-nal magnitllde, the ef~ective gain being greater for small sig-nals. An ex~mple of a compandor (compressor/expander) is MC33110 manufactured by Motorola, Inc. The dynamic range ~0 of the compandor is 80 dB.
The output of the compressor (114) is input to a pre-em-phasis filter (115) before being scr~mhle~ by the scrambler cir-cuit (116). The scrambler circuit (116) is the second half of the same integrated (,ircuit used to unscramble the received sig-25 nal. The serambled audio signal is bandpass filtered (117) be-fore being rnodulated by the transmitter (118) to a ~requency in the range of'46.610 - 46.970 MHz. The actual ~requency used by the telephone can be user selectable by a switch or other con-trol on the telephone base or remote. Both the receive and 30 transmit frequency ranges are set by the FCC for all cordless telephones. An example of a transmitter is MC2833 manufac-hlred by Motorola, Inc.
The output of the transmitter is bandpass filtered t119) to filter out the signal outside the 46.B10 - 46.970 MHz range.
35 This signal is then transmitted from the antenna (101) to the remote unit.
2~2~7 The remote unit is comprised of the s~ntenn~ (201) that receives the signal Çrom the base unit. A bandpass filter (202) removes that part of the signal outside the range of 46.610 -46.97û MHz. A gain of approximately 18 dB is then applied to 5 the signal by a receive ampli~ler (203) before it is bandpass f;l-tered (204) again. This signal is then input to the recelver (205).
The remote unit receiver (205) mixes the signal down to 10.7 MHz and then to 45~ kHz. This signal is then demodu-10 lated. The demodulated signal, labeled RX Data, is input tothe microproces50r (212) to interpret the coded data ~ness~es transrnitted by the base unit. These coded data messages are used to control the remote ringer and the scrambling circuit.
The demodulated signal is also bandpass filtered (206) l5 before being input to the scrambler circuit (207) for descram-bling. The scrambler circuit (207) is identical to the integrated circuit used in the base unit.
The unscrambled output is filtered by a de-emphasis fil-ter (20~) before going through an expander (209). The ex-~D panded signal is bandpass ~Itered (210) and amplified (211).The amplifier (211) is controlled by the microprocessor (212).
By operating a control cn the remote unit, the user can in-crease or decrease the speaker (220) volume by increasing or decreasing the gain applied to the signal at this point. The 25 amplified signal is input to the earpiece speaker of the remote unit.
The microphone (221) of the remote generates the audio signal that is bandpass filtered (213), compressed (214), and filtered by a pre-emphasis filter (215) before being processed by 30 the scrambler circuit (216). This circuit (~16) is the seeond half of the integrated circuit used to unscramble the received signal.
The scrambled signal is bandpass ~ltered (217) before being modulated to a frequency in the range oii 49.67 - 49.99 35 MHz by the transmitter (218). The modulated signal is band-2~7~257 ~6-pass filtered ~219) to remove the signal outside this frequency range and is transmitted on the remote's antem~a (201).
I~e keypad on the remote (22~) is used to take the tele-phone off hook, enter telephone numbers, chan~e the fre-quency used to cornmunicate with the base, and to enable the scramble demonstration fimction. The keylpad enables the scr~mhling demonstration function by telling the micropro-cessor to generate a control signal to the scr~mhling inte-grated circuit. In the preferred emboAim~nt, the base unit 10 also has a keypad.
The control signals in both the remote and the base units are connected to the transmitter after the scrs~rnhling function so that these signals are not scrambled. The controi signals, generated by the microprocessor, are wire-OiRed wi.th 15 the scrambled voice signal to the transmitter input.
The scrambling of the signal between the remote and the base is operating continuously. This scrslnnhling, how-ever, is not evident to the telephone user or the party on the other end of the call. It would not be known, therefore, if the ~0 scrambling was operating properly. The scram~ling demon-stration process of the present invention provides both parties to the telephone call the ability to hear ~he scrambled version of the signal.
The scrambling demonstration process is illustrated in 25 FIG. 3. While the telephone is in a call, the keypad is scanned (301) by the microprocessor for the depression of a key, such as a Secure Demo key, that indicates that the remote unit user w~shes to enter the scrambling demonstratioIl mode. In the preferred embodiment, this mode is referred to as the Secure 30 Demo mode.
If the key i6 depressed (302), a timer in the microproces-sor i9 started (303). If the key is released immediately (304), the timer is cleared (305) and the keypad scanned again (301).
If the key is still depressed (304), the timer is incremented 35 (306) and checked to determine if the key has been depressed for at least 3 seconds (307). This time check is comtinued until 2~7~25~
the key has been depressed for 3 seconds. At this point, the scrambling demonstration mocle is operating (304). Thi~ ca be indicated on the remote or the base by fl~hinE inrlic~qtor lights (309). The remote keypad may be used -~or the a~ove pro-5 cess or, if the base has a keypad, this keypad may be used toenter the scrambling demonstration mode.
The block diagram of the MX108DW Full-Duplex Voiceband Scrambler integrated circuit is illustrated in FIG.
4. Since this integrated circuit uses frequency inversion 10 scrambling, a signal that is input to the circuit that has al-ready been scrambled will be returned to normal by the cir-cuit.
In order to put the telephone into the scrambling demonstration mode, the MX1()8DW mu~t be able to transm~t 1~ the input signal without scrambling. This is accornpli~hecl by the control input labeled Clear/Scramble. By applying a logic o:ne to this input, the signal is transmitted through the path via the clear path. A logic zero on this control input will cause ~e signal to be transm~tted through the path via the scramble ~) path.
The pref~rred embodiment of the present invention dis-ables the entire scrambling inte~rated circllit in the rsmote unit when the scrarnbling demonstration mode is initia$ed.
This allows the scrambled audio signal to be heard by both the telephone user and the land-line party to the conversation.
In an alternate embodiment, the scrambling circuits in the receive paths of both the base and remote units are dis-abled in the scrambling demonstratiQn mode. This embodi-ment, however, requires that a comm~r~d be sent by the unit 30 that is initiating the scrambling demonstration mode to the other unit, instructing the receiving unit to disable the receive path scrambling circuit. This command can be transmittecl during block (308) of FIG. 3.
In another embodiment of the present invelltion, the 35 base sp0akerphone can also have a scrambling circuit. This allows a conversation between the speakerphone and the laTld-~7~
lme party to also use the scrambling demonatration mode.
This can be enabled in the same manner is illustrated in FIG.
3.
The preferred embodiment disables the scr~qn hlin~ cir-cuits until any key is depressed, causing the disabled scram bling circuits ~o be enabled. Alternate embo-linnents can dis-able the scrambling circuits for a predetermined time. The scrambling circuits can also be enabled, and thus the scram~
bling demonstration mode ended, upon hang-up of the call in - 1D progress.
In summ~rry, a wireless or cordless telephone having controllable scrambling between the remote unit and the base unit has been shown, thus providing secure conversations be-tween the telephone user and the land-line lparty. Using the present invention, telephone user can still enjoy the conve-nience of a cordless telephone without unwanted parties Xis-tening to the conversation. Additionally, the present inYent,ion allows the scrambled signal to be heard by each party, in a l~rr onstration mode, to determine that the scrambling cir-~0 cuitry is operating properly.
In order to put the telephone into the scrambling demonstration mode, the MX1()8DW mu~t be able to transm~t 1~ the input signal without scrambling. This is accornpli~hecl by the control input labeled Clear/Scramble. By applying a logic o:ne to this input, the signal is transmitted through the path via the clear path. A logic zero on this control input will cause ~e signal to be transm~tted through the path via the scramble ~) path.
The pref~rred embodiment of the present invention dis-ables the entire scrambling inte~rated circllit in the rsmote unit when the scrarnbling demonstration mode is initia$ed.
This allows the scrambled audio signal to be heard by both the telephone user and the land-line party to the conversation.
In an alternate embodiment, the scrambling circuits in the receive paths of both the base and remote units are dis-abled in the scrambling demonstratiQn mode. This embodi-ment, however, requires that a comm~r~d be sent by the unit 30 that is initiating the scrambling demonstration mode to the other unit, instructing the receiving unit to disable the receive path scrambling circuit. This command can be transmittecl during block (308) of FIG. 3.
In another embodiment of the present invelltion, the 35 base sp0akerphone can also have a scrambling circuit. This allows a conversation between the speakerphone and the laTld-~7~
lme party to also use the scrambling demonatration mode.
This can be enabled in the same manner is illustrated in FIG.
3.
The preferred embodiment disables the scr~qn hlin~ cir-cuits until any key is depressed, causing the disabled scram bling circuits ~o be enabled. Alternate embo-linnents can dis-able the scrambling circuits for a predetermined time. The scrambling circuits can also be enabled, and thus the scram~
bling demonstration mode ended, upon hang-up of the call in - 1D progress.
In summ~rry, a wireless or cordless telephone having controllable scrambling between the remote unit and the base unit has been shown, thus providing secure conversations be-tween the telephone user and the land-line lparty. Using the present invention, telephone user can still enjoy the conve-nience of a cordless telephone without unwanted parties Xis-tening to the conversation. Additionally, the present inYent,ion allows the scrambled signal to be heard by each party, in a l~rr onstration mode, to determine that the scrambling cir-~0 cuitry is operating properly.
Claims (21)
1. A wireless communication system having a base unit, coupled to a land-line telephone system, and a remote unit, the remote unit communicating with the base unit over a communication medium, the system comprising:
first encryption means located in a transmit path of the remote unit, for encrypting voice signals transmitted to the base unit;
first decryption means, located in a receive path of the remote unit, for decrypting voice signals received from the base unit;
second encryption means, located in a transmit path of the base unit, for enclosing voice signals transmitted to the remote unit;
second decryption means, located in a receive path of the base unit, for decrypting voice signals received from the remote unit; and control entry means for generating a control signal to disable the first and second decryption means.
first encryption means located in a transmit path of the remote unit, for encrypting voice signals transmitted to the base unit;
first decryption means, located in a receive path of the remote unit, for decrypting voice signals received from the base unit;
second encryption means, located in a transmit path of the base unit, for enclosing voice signals transmitted to the remote unit;
second decryption means, located in a receive path of the base unit, for decrypting voice signals received from the remote unit; and control entry means for generating a control signal to disable the first and second decryption means.
2. The system of claim 1 wherein the first and second decryption means are disabled for a predetermined time.
3. The system of claim 1 wherein the first and second decryption means are disabled until the control entry means generates a control signal to enable them.
4. The system of claim 1 wherein the first and second decryption means are enabled when an ongoing telephone call is terminated.
5. A wireless communication system, comprising:
a base unit having a receive path and a transmit path, the receive path comprising: first receiving means, for receiving voice and control signals and first decryption means for decrypting the voice signals, the transmit path comprising:
first transmitting means for transmitting voice signals and first encryption means for encrypting the voice signals;
a remote unit that communicates over radio frequencies with the base unit, the remote unit having a receive path and a transmit path, the receive path comprising: second receiving means, for receiving the voice signals and second decryption means for decrypting the voice signals, the transmit path comprising: electro-audio transducer means for generating voice signals, second encryption means for encrypting the voice signals, and second transmitting means for transmitting the voice and control signals to the base unit; and control entry means for generating the control signals that disable the first and second decryption means.
a base unit having a receive path and a transmit path, the receive path comprising: first receiving means, for receiving voice and control signals and first decryption means for decrypting the voice signals, the transmit path comprising:
first transmitting means for transmitting voice signals and first encryption means for encrypting the voice signals;
a remote unit that communicates over radio frequencies with the base unit, the remote unit having a receive path and a transmit path, the receive path comprising: second receiving means, for receiving the voice signals and second decryption means for decrypting the voice signals, the transmit path comprising: electro-audio transducer means for generating voice signals, second encryption means for encrypting the voice signals, and second transmitting means for transmitting the voice and control signals to the base unit; and control entry means for generating the control signals that disable the first and second decryption means.
6. The system of claim 5 wherein the control entry means is located in the remote unit.
7. The system of claim 5 wherein the control entry means is located in the base unit.
8. The system of claim 5 wherein both the remote unit and the base unit contain control entry means.
9. A wireless communication system having a base unit, coupled to a land-line telephone system, and a remote unit that communicates with the base unit over radio frequencies, the system comprising:
first encryption means, located in a transmit path of the remote unit, for encrypting voice signals transmitted to the base unit;
first decryption means, located in a receive path of the remote unit, for decrypting voice signals received from the base unit;
second encryption means, located in a transmit path of the base unit, for encrypting voice signals transmitted to the remote unit;
second decryption means, located in a receive path of the base unit, for decrypting voice signals received from the remote unit; and control entry means, located in the remote unit, for generating a control signal to disable the first decryption means and the first encryption means.
first encryption means, located in a transmit path of the remote unit, for encrypting voice signals transmitted to the base unit;
first decryption means, located in a receive path of the remote unit, for decrypting voice signals received from the base unit;
second encryption means, located in a transmit path of the base unit, for encrypting voice signals transmitted to the remote unit;
second decryption means, located in a receive path of the base unit, for decrypting voice signals received from the remote unit; and control entry means, located in the remote unit, for generating a control signal to disable the first decryption means and the first encryption means.
10. A method for enabling a scrambling demonstration mode in a communications device having a base unit and a remote unit, the base unit being coupled to a land-line telephone system, the base and remote units communicating with each other by scrambled voice signals transmitted at radio frequencies, at least the remote unit having a keypad, the method comprising thesteps of:
scanning the keypad for the activation of a scrambling demonstration key; and if the scrambling demonstration key is activated for a predetermined time, enabling the scrambling demonstration mode to allow the scrambled voice signals to be heard at least by a user of the remote unit or a user of the land-line telephone system.
scanning the keypad for the activation of a scrambling demonstration key; and if the scrambling demonstration key is activated for a predetermined time, enabling the scrambling demonstration mode to allow the scrambled voice signals to be heard at least by a user of the remote unit or a user of the land-line telephone system.
11. A wireless communication system having a base unit, coupled to a land-line telephone system, and a remote unit communicating with the base unit over a communication medium, the system comprising:
first frequency inversion encryption means, located in a transmit path of the remote unit, for encrypting voice signals transmitted to the base unit;
first frequency inversion decryption means, located in a receive path of the remote unit, for decrypting voice signals received from the base unit;
voice signals received from the base unit;
second frequency inversion encryption means, located in a transmit path of the base unit, for encrypting voice signals transmitted to the remote unit;
second frequency inversion decryption means, located in a receive path of the base unit, for decrypting voice signals received from the remote unit; and control entry means for generating a control signal to disable the first and second frequency inversion decryption means.
first frequency inversion encryption means, located in a transmit path of the remote unit, for encrypting voice signals transmitted to the base unit;
first frequency inversion decryption means, located in a receive path of the remote unit, for decrypting voice signals received from the base unit;
voice signals received from the base unit;
second frequency inversion encryption means, located in a transmit path of the base unit, for encrypting voice signals transmitted to the remote unit;
second frequency inversion decryption means, located in a receive path of the base unit, for decrypting voice signals received from the remote unit; and control entry means for generating a control signal to disable the first and second frequency inversion decryption means.
12. The system of claim 11 wherein the first and second frequency inversion decryption means are disabled for a predetermined time.
13. The system of claim 11 wherein the first and second frequency inversion decryption means are disabled until the control entry means generates a control signal to enable them.
14. The system of claim 11 wherein the first and second frequency inversion decryption means are enabled when an ongoing telephone call is terminated.
15. A wireless communication system, comprising:
a base unit having a receive path and a transmit path, the receive path comprising: first receiving means, for receiving voice and control signals and first frequency inversion decryption means for decrypting voice signals, the transmit path comprising: first transmitting means for transmitting voice signals and first frequency inversion encryption means for encrypting the voice signals;a remote unit that communicates over radio frequencies with the base unit, the remote unit having a receive path and a transmit path, the receive path comprising: second receiving means, for receiving the voice signals and second frequency inversion decryption means for decrypting the voice signals, the transmit path comprising: electro-audio transducer means for generating voice signals, second frequency inversion encryption means for encrypting voice signals, and second transmitting means for transmitting the voice and control signals to the base unit; and control entry means for generating the control signals that disable the first and second frequency inversion decryption means.
a base unit having a receive path and a transmit path, the receive path comprising: first receiving means, for receiving voice and control signals and first frequency inversion decryption means for decrypting voice signals, the transmit path comprising: first transmitting means for transmitting voice signals and first frequency inversion encryption means for encrypting the voice signals;a remote unit that communicates over radio frequencies with the base unit, the remote unit having a receive path and a transmit path, the receive path comprising: second receiving means, for receiving the voice signals and second frequency inversion decryption means for decrypting the voice signals, the transmit path comprising: electro-audio transducer means for generating voice signals, second frequency inversion encryption means for encrypting voice signals, and second transmitting means for transmitting the voice and control signals to the base unit; and control entry means for generating the control signals that disable the first and second frequency inversion decryption means.
16. The system of claim 15 wherein the control entry means is located in the remote unit.
17. The system of claim 15 wherein the control entry means is located in the base unit.
18. The system of claim 15 wherein both the remote unit and the base unit contain control entry means.
19. A wireless communication system having a base unit, coupled to a land-line telephone system, and a remote unit that communicates with the base unit over radio frequencies, the system comprising:
first frequency inversion encryption means, located in a transmit path of the remote unit, for encrypting voice signals transmitted to the base unit;
first frequency inversion decryption means, located in a receive path of the remote unit, for decrypting voice signals received from the base unit;
second frequency inversion encryption means, located in a transmit path of the base unit, for encrypting voice signals transmitted to the remote unit; p1 second frequency inversion decryption means, located in a receive path of the base unit, for decrypting voice signals received from the remote unit; and control entry means, located in the remote unit, for generating a control signal to disable the first frequency inversion decryption means and the first frequency inversion encryption means.
first frequency inversion encryption means, located in a transmit path of the remote unit, for encrypting voice signals transmitted to the base unit;
first frequency inversion decryption means, located in a receive path of the remote unit, for decrypting voice signals received from the base unit;
second frequency inversion encryption means, located in a transmit path of the base unit, for encrypting voice signals transmitted to the remote unit; p1 second frequency inversion decryption means, located in a receive path of the base unit, for decrypting voice signals received from the remote unit; and control entry means, located in the remote unit, for generating a control signal to disable the first frequency inversion decryption means and the first frequency inversion encryption means.
20. A method for enabling a scrambling demonstration mode in a communications device having a base unit and a remote unit, the base unit coupled to a land-line telephone system, the base and remote units communicating with each other by frequency inversion scrambled voice signals transmitted at radio frequencies, at least the remote unit having a keypad, the method comprising the steps of:
scanning the keypad for the activation of a scrambling demonstration key; and if the scrambling demonstration key is activated for a predetermined time, enabling the scrambling demonstration mode to allow the scrambled voice signals to be heard at least by a user of the remote unit and a user of the land-line telephone system.
scanning the keypad for the activation of a scrambling demonstration key; and if the scrambling demonstration key is activated for a predetermined time, enabling the scrambling demonstration mode to allow the scrambled voice signals to be heard at least by a user of the remote unit and a user of the land-line telephone system.
21. The method of claim 20 wherein the predetermined time is 3 seconds.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US755,970 | 1991-09-06 | ||
| US07/755,970 US5168522A (en) | 1991-09-06 | 1991-09-06 | Wireless telephone with frequency inversion scrambling |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2075257A1 CA2075257A1 (en) | 1993-03-07 |
| CA2075257C true CA2075257C (en) | 1998-01-20 |
Family
ID=25041459
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002075257A Expired - Fee Related CA2075257C (en) | 1991-09-06 | 1992-08-04 | Wireless telephone with frequency inversion scrambling |
Country Status (5)
| Country | Link |
|---|---|
| US (1) | US5168522A (en) |
| AR (1) | AR247322A1 (en) |
| BR (1) | BR9203471A (en) |
| CA (1) | CA2075257C (en) |
| MX (1) | MX9205091A (en) |
Families Citing this family (17)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP3138296B2 (en) * | 1991-09-10 | 2001-02-26 | ローム株式会社 | Modulation / demodulation circuit and communication system using the same |
| US5392354A (en) * | 1991-10-30 | 1995-02-21 | Fujitsu Limited | Cordless phone system capable of scrambling communication signals |
| SE501033C2 (en) * | 1993-04-27 | 1994-10-24 | Saab Scania Combitech Ab | Wireless and encrypted information transfer system |
| FR2703199B1 (en) * | 1993-03-26 | 1995-06-02 | Matra Communication | Radio transmission method using repeating spectrum inverting stations. |
| US5335279A (en) * | 1993-07-30 | 1994-08-02 | Texas Instruments Incorporated | Digital voice-band spectrum inversion apparatus |
| JPH08265211A (en) * | 1995-03-22 | 1996-10-11 | Sony Corp | Integrated circuit and transmitter-receiver |
| KR19980021370A (en) * | 1996-09-16 | 1998-06-25 | 김광호 | Method and device for prevention of eavesdropping on call of wireless telephone |
| US5907538A (en) * | 1997-02-18 | 1999-05-25 | White; Donald R. | Full duplex communication circuit with a transducer for simultaneously generating audio output and receiving audio input |
| US7072476B2 (en) * | 1997-02-18 | 2006-07-04 | Matech, Inc. | Audio headset |
| US6256491B1 (en) * | 1997-12-31 | 2001-07-03 | Transcript International, Inc. | Voice security between a composite channel telephone communications link and a telephone |
| JP4519963B2 (en) * | 1999-06-21 | 2010-08-04 | 富士通株式会社 | Biometric information encryption / decryption method and apparatus, and personal authentication system using biometric information |
| US6597301B2 (en) * | 2001-10-03 | 2003-07-22 | Shure Incorporated | Apparatus and method for level-dependent companding for wireless audio noise reduction |
| US7826805B2 (en) * | 2003-11-11 | 2010-11-02 | Matech, Inc. | Automatic-switching wireless communication device |
| RU2370890C2 (en) * | 2003-11-11 | 2009-10-20 | Матек, Инк. | Two-way communication device containing one transducer |
| US8315379B2 (en) * | 2004-11-10 | 2012-11-20 | Matech, Inc. | Single transducer full duplex talking circuit |
| US8930182B2 (en) * | 2011-03-17 | 2015-01-06 | International Business Machines Corporation | Voice transformation with encoded information |
| CN114006622B (en) * | 2021-11-03 | 2023-07-07 | 王赓 | Artificial intelligence signal transmitting device for 5G communication |
Family Cites Families (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4228321A (en) * | 1978-05-16 | 1980-10-14 | Bell Telephone Laboratories, Incorporated | Privacy transmission system with remote key control |
| US4555805A (en) * | 1980-03-14 | 1985-11-26 | Harris Corporation | Secure mobile telephone system |
| US4411017A (en) * | 1980-03-14 | 1983-10-18 | Harris Corporation | Secure mobile telephone system |
| US4920567A (en) * | 1986-07-03 | 1990-04-24 | Motorola, Inc. | Secure telephone terminal |
| US4827507A (en) * | 1987-06-19 | 1989-05-02 | Motorola, Inc. | Duplex analog scrambler |
| US4972479A (en) * | 1987-07-10 | 1990-11-20 | Tobias Jr Ray W | Method and apparatus for providing privacy/security in a communication system |
| US4989230A (en) * | 1988-09-23 | 1991-01-29 | Motorola, Inc. | Cellular cordless telephone |
| US5140635A (en) * | 1991-09-06 | 1992-08-18 | Motorola, Inc. | Wireless telephone with frequency inversion scrambling |
-
1991
- 1991-09-04 BR BR929203471A patent/BR9203471A/en not_active IP Right Cessation
- 1991-09-06 US US07/755,970 patent/US5168522A/en not_active Expired - Fee Related
-
1992
- 1992-08-04 CA CA002075257A patent/CA2075257C/en not_active Expired - Fee Related
- 1992-09-04 MX MX9205091A patent/MX9205091A/en not_active IP Right Cessation
- 1992-09-04 AR AR92323114A patent/AR247322A1/en active
Also Published As
| Publication number | Publication date |
|---|---|
| US5168522A (en) | 1992-12-01 |
| CA2075257A1 (en) | 1993-03-07 |
| BR9203471A (en) | 1993-04-13 |
| AR247322A1 (en) | 1994-11-30 |
| MX9205091A (en) | 1993-03-01 |
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| EEER | Examination request | ||
| MKLA | Lapsed |