US 3725589 A
An interface between a telephone system and dictating equipment whereby control signals and intelligence are transmitted over the telephone system and to the dictating equipment to appropriately record the intelligence while eliminating any recordation of the control signals.
Claims available in
Description (OCR text may contain errors)
United States Patent 1191 Golden 14 1 Apr. 3, 1973  REMOTE-CONTROL SYSTEM FOR 3,405,234 10/1968 West ..179/1oo.1 DR INTELLIGENCERECORDING 3,449,530 6/1969 Watts ..179 100.2 s APPARATUS WITH CONTROL TONE N ELIMENATING SWITCHING FOREIG PATENTS OR APPLICATIONS 936,814 9/1963 Great Britain ..l79/6 E  Inventor: Michael E. Golden, 1700 Midvale Avenue Los Angeles Cahf' 90024 Primary Examiner-Raymond F. Cardillo, Jr.  Filed: Feb. 14, 1972 AttorneyBilly A. Robbins et al.
2  Appl No 225,8 8 ABSTRACT I 52 Us. 131 .,.179/6 E 179/2 A 179/1001 DR An interface between a elephme System and 51 1111.01. 31104111 11/10, G1 lb 19 2 s equipment hfi Control Signals a intel-  Field 0fsearch n 179/1001 DR 1002 S ligence are transmitted over the telephone system and 79/6 C 6 E 2 A 2 to the dictating equipment to appropriately record the I i 340/ ]71 P14 ntelligence while eliminating-any recordation of the control signals.  References Cited 12 Claims, 3 Drawing Figures UNITED STATES PATENTS 3,436,483 4/1969 Blane ..l79/6 E 28 T T M TONE GG/VERATOQ l 77ME COMMON SAC/4 DEL/J Y FREQUGNC Y SWITCH D5 rec T012 ji /4 CONTROL //5 meouem/es 0er5c7'02(s) ill] WTEQFAQ;
r'rn CONTROL 4 escoeo secr/o/v 54 6EC77OA/ /3O PATENTEUAPR3 I373 SHEET 3 UF 3 kDDQS Oh REMOTE-CONTROL SYSTEM FOR INTELLIGENCE-RECORDING APPARATUS WITH CONTROL TONE ELIMINATING SWITCHING CROSS-REFERENCES TO KNOWN RELATED PATENTS The following issued U.S. Pat. Nos. may be of interest: 3,381,276; 3,549,821; 2,883,866; 3,296,371; 3,222,460; 3,360,613.
BACKGROUND OF INVENTION Remote control of electronic equipment particularly that for recording intelligence and particularly that where touch-tone telephone signals are used therefor are well known. U.S. Pat. Nos. 3,549,821 directed to dictation systems and 3,381,276 directed to computer' systems are exemplary of such art. Where utilizing such systems, it has been found desirable to preclude recordation of the control signals upon the primary recording medium without interference with the recording of the intelligence transmitted to the recording medium. In the prior art solutions to this problem there has been utilized voice-controlled mechanisms such as that described in U.S. Pat. No. 2,833,866, a voice buffer with appropriate delay or an automatic motor reverse and erase such as described in U.S. Pat. No. 3,549,821 or a continuous close-looped intermediate recording media such as that shown in U.S. Pat. No. 3,360,613.
SUMMARY OF THE INVENTION Means is provided for generating control signals each of which includes a pair of constant frequency signals. The frequency of one of the pair of signals is common to all of the control signals. Means responsive to the common signal of the dual-frequency signal-pair is provided for precluding passage of any control or intelligence signal to the recording medium during the presence of the common signal. Such common signal responsive means may also function to allow passage of control signals to appropriate portions of the apparatus only during presence of the common signal.
BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 illustrates a remote-control apparatus in accordance with the present invention;
FIG. 2 is a schematic representation more in detail of a portion of the system as illustrated in FIG. 2; and,
FIG. 3 is a schematic representation of the control logic of a system as illustrated in FIG. 1.
AN EMBODIMENT OF THE INVENTION The present invention will be described in conjunction with dictating equipment which is to be remotely controlled from a telephone which may be located anyplace and through which both control and intelligence signals are transmitted. It should, however, be understood that the present invention is not to be limited to. the control of dictating equipment only by such description. The invention has utility in any system where both intelligence and control signals are to be transmitted to a remote point over lines on which voice or analog data may reasonably expect to be found at the same time for control of electronic equipment such for example, as a computer, other business machines, or lighting and appliances.
Referring now particularly to FIG. 1, there is illustrated in block form, apparatus constructed in accordance with the present invention. As is therein shown, an interface 10 is disposed between a telephone system 20 and recording equipment 30. The interface 10 may be utilized to couple any type of dictating equipment having the normal functions of record, stop, play and backup to any telephone system. The interface 10 may be used in a central dictating-transcribing system where a plurality of subscribers call the dictating equipment as needed. Alternatively, the interface 10 may be used as part of the dictating-transcribing system used in a typical business office. In either event, the subscriber merely places a telephone call through the normal operation of the telephone system 20 to a telephone number which has been assigned to the interface 10. The interface 10 upon receiving the ring from the telephone system is on-line for both control of the dictating equipment 30, by signals generated by the subscriber and transmitted through the telephone system 20, and clean transmission of dictation to the recording medium thereof.
. Preferably, the telephone system 20 for utilization with the interface 10 includes a Touch-Tone (trademark of American Telephone & Telegraph Company) telephone 22. As is well known at the present time, the telephone 22 as presently provided the public includes 12 buttons arranged in a matrix of three columns (A, B, and C) vertically disposed and four rows (D, E, F, and G) horizontally disposed. As is also known, on special order for particular applications, an additional column of four buttons may be obtained on a telephone thus providing 16 buttons thereon. In any event, the present system is compatible with 12-button telephones, 16- button telephones, or a telephone having any number of buttons thereon. Each vertical column of buttons has a common frequency signal assigned to each of the buttons appearing therein. For example, column A is assigned a frequency of 1,209 Hz; column B 1,336 Hz and column C 1,477 Hz. Each of the horizontal rows is also assigned a common frequency, thus row D is assigned a common frequency of 697 Hz, row E 770 Hz, row F 852 Hz and row G 941 Hz. Thus, it can be seen that depression of any of the buttons appearing on a touch-tone telephone will generate a unique dualfrequency signal-pair for that particular button. Thus, if the button appearing in column A and row D is depressed, a pair of signals is generated one of which has a frequency of 697 Hz and the other of which has a frequency of 1,209 Hz. It will also be recognized that by depressing any of the buttons in column A, there will be generated a signal having a frequency of 1,209 Hz. This unique fact that a common frequency signal is generated when each of the buttons appearing in any specific column is depressed is taken advantage of by the present invention. It should be noted that the symbols l, 4, 7 and have been assigned to each of the buttons appearing in column A rows D, E, F, and G, respectively. By assigning a particular control function to each of these buttons appearing in column A, such for example when utilizing dictating equipment, as record for button 1, play/backup for button 4, .stop for button 7, and signal for button one can uniquely accomplish control of dictating equipment by utilizing only a signal column of buttons, each of which generates its own dual-frequency signal-pair, one of which is a common signal to each of the buttons while the other of which is uniquely different from each of the other signals. As is shown, the Touch-Tone telephone 22 is connected by way of a line 24 which is illustrative of the telephone system to the interface 10. A receiver-transmitter 26 may be used in well-known fashion for transmission of desired information by voice or data through the interface to the dictating equipment 30.
Through the utilization of a tone generator 28, the present invention may be utilized with a standard rotary dial-type telephone 29. As is illustrated by the dashed line 24A, the rotary dial-type telephone 29 would be connected to the telephone system and through the interface 10 to the dictating equipment 30. The tone generator 28 would be utilized only in those areas where a Touch-Tone telephone is not available. As is shown on the tone generator 28, four buttons could be utilized each having the same symbol assigned thereto as does each column of buttons on the Touch- Tone telephone 22. The tone generator would also be arranged in such a fashion that depression of each of the buttons 1, 4, 7 and thereon would generate a signal-pair having frequencies identical to those generated upon depression of the buttons bearing the same symbol on the Touch-Tone telephone 22. Obviously any number of buttons could be used dependent solely upon the particular application so long as the proper dual-frequency signal-pair is generated upon depression of a given button. The signals thus generated would be transmitted over the telephone system to the dictating equipment 30, as above indicated.
As shown in the interface 10, there is included a common frequency detector(s) means 12 which upon the presence on the incoming line 24 of a signal having the common frequency, for example only of 1,209 Hz, detects the same and produces an output signal. That output signal is applied to a switch means 14 and a time-delay switch means 16. The switch means 14 is connected to the incoming line 24 and also to the dictating equipment 30. The switch means 14 functions in response to the output signal from the common frequency detector 12 to block or preclude transmission to the dictating equipment 30 of any signals appearing on the line 24.
The time-delay switch means 16 is connected to a control frequencies detector(s) 18 and functions in response to an output signal from the common frequency detector 12 to permit passage or transmission of any signals appearing on line 24 to the control frequencies detector 18, which are in turn connected to the dictating equipment 30. Thus, as will be more fully explained Hz (the common frequency to column A), information appearing on line 24 is transmitted through the switch means 14 to the record section 34 of the dictating equipment 30 but no signals are permitted to pass to the control frequencies detector(s) 18. Through the utilization of the time-delay switch 16, the possibility of voice simulation of a particular control frequency is below, upon the occurrence of the common signal havsubstantially eliminated. That is, even though a subscriber may, in speaking, generate a tone of, for example 1,209 Hz, he will not sustain that tone for a time sufficient to activate the time-delay switch 16 and thereby the control frequencies detector(s).
Referring now more particularly to FIG. 2, there is therein illustrated in more detail the common frequency detector 12 and the switch means 14 and .16 as previously described with reference to FIG. 1. As is illustrated in FIG. 2, an isolating transformer 42 is utilized to interconnect the incoming signals from the telephone system, which appear on the primary winding 44, to the interface 10 which is connected to the secondary winding 46.
As is well understood by those skilled in the art, also interconnected between the telephone system and the interface 10 will be ring detectors, hold and latchup circuits and dropout circuits. These circuits are well known in the prior art and enable one to call a particular telephone number which is assigned by the telephone company to the interface 10 to thereby establish communication with specific equipment, that is to be controlled and/or is to receive intelligence signals. The ringing of'the telephone is detected by the ring-detector circuit and upon such detection holding relays are actuated and latched in place to retain the communication between the transmitter and the electronic equipment to be controlled. This communication is maintained typically for predetermined periods of time ascertained by timing circuits which are sensitive to the presence or lack thereof of control signals, voice signals, or the like within the interface circuits. In the absence of such signals, the timing circuits cause a signal to occur which will then effectively hang up or drop out the connection between the telephone system and the interface thus freeing the line for subsequent callers to utilize. The ensuing description of the present invention assumes that a subscriber has directed the appropriate telephone number to the interface 10 and that the interface 10 has detected the same and has caused the appropriate circuits to become energized to connect the telephone line to the interface and establish appropriate communication. It would also be assumed that the subscriber has received a signal returned from the interface, which indicates that the equipment is ready for utilization. At this point in time, the subscriber may depress one of the four buttons in column A of the Touch-Tone telephone 22 or on the tone generator 28 as above described to cause the dictating equipment to go into the proper operational mode for his purposes. It will be assumed that button number 1, for record, is depressed by the subscriber.
As above pointed out, depression of button number 1 causes the simultaneous generation of a signal-pair one of which is the common frequency of 1,209 Hz and the other of which is 697 Hz. This signal-pair is transmitted through the transformer 42 and is applied by the lead the amplifier 50 through the lead 54, the relay 60, and to the control frequencies detectors 110-116 by way of the lead 108.
It can therefore be seen that upon the detection of the 1,209 Hz common signal by the detector 12, and after a predetermined time period, as determined by the time constants of the capacitor 86 and resistor 90, the relay 60 is closed. The time constant is chosen to have a time sufficient to preclude energization of the relay 60 as a result of the occurrence of the frequency of 1,209 Hz for a short period of time, as in voice signals or the like. It has been determined that a time delay of. approximately 75 milliseconds is adequate to accomplish the desired results thereby precluding voice simulation of control frequencies.
When the reed relay 60 is energized, control signals generated by depressing one of buttons 1, 4, 7, or are transmitted in such a way as to be simultaneously applied to the detectors 110, 112, 114, and 116. In the event a signal having a frequency within the detection band of any one of the detectors is present on the line, that detector will provide an output signal in the same manner as described with respect to the detector 12 above. Thus, if a 697 Hz signal is the other frequency of the signal-pair being transmitted, detector 110 provides an output signal on the lead 118. This signal is then transmitted to the logic 126 which in turn applies by way of the connection 128, a signal to an appropriate control relay 130. The control relay is connected by a connection 132 to the control section 32 of the dictating equipment 30. In addition thereto, a manual control means 134 may be connected by a connection 136 into the logic 126. Such manual control is sometimes desirable at the station where the dictating machine is located to provide minipulation for changing recording media or the like. I
It has also been determined that when the dictating equipment is in a predetermined mode of operation such for example as stop, it is desirable to provide an audible signal which may be transmitted over the telephone system to the subscriber so indicating. Thus, as is illustrated also in FIG. 2, an audio-oscillator 184 (FIG. 3) may be connected to the lead 62 as shown. at 134. A signal from the audio-oscillator would be applied as a result of the operation of the logic 126 so as to be transmitted through the transformer 42 and back to the subscriber. It has been found that when such audio signals are transmitted, they are received by the dictating equipment and as a result of the automatic gain-control features of most dictating equipment, the audio tone causes the gain to be reduced drastically. As a result, if the subscriber then depresses the record control button and commences to dictate, the initial dictation, sometimes for several seconds, will be extremely weak because the automatic gain control (AGC) is still functioning as a result of the previous audio tone input thereto from the oscillator. To overcome this problem and as part of the present invention, a shunting transistor 136 is utilized to shunt to ground the audio signal which would normally be applied to the dictating equipment when the same is being applied to the transformer 42. To this effect, the transistor 136 has its collector connected to the lead 138, which is connected between the lead 62 and the terminal 64 of the reed relay 68, the emitter thereof being connected to ground. The base of the transistor 136 is connected through a base resistor 140 to the logic 126. The logic 126, upon application of the audio signal to lead 134 simultaneously energizes the base of the transistor 136 causing it to conduct in saturation to thereby preclude the signal effecting the AGC circuitry of the dictating equipment.
Referring now to FIG. 3, a simplified form of the logic 126 is illustrated. As is therein shown, a flip-flop 140 has its input terminal 142 connected to the output of the record signal detector by way of the lead 118 while the other terminal 144 is connected by way of lead to the output of the play backup detector 112. The output terminal 146 of the flip-flop is connected to the record relay 148 while the output terminal 150 thereof is connected as one input to NAND gate 152, the output of which is connected to the play lamp 154. It should also be noted that the output of the play backup detector 112 is also connected as one input 156 to the OR gate 158, the other input 160 thereof being connected to the output of the record detector 110. The output of the OR gate is connected by way of the lead 162 as one input to the run flip-flop 164. The other input 166 to the flip-flop 164 is connected by way of a lead 122 to the stop signal detector 114 and also by way of the lead 124 to the output of the signal detector 116. One output terminal 168 of the flip-flop 164 is connected to the run relay 170 and is also connected by way of the lead 172 as the other input to the NAND gate 152. The other output terminal 174 of the flip-flop 164 is connectedto the stop lamp 176. It should also be noted that the play backup relay is connected by way of the lead 182 to the output of the play backup detector 112.
- In addition, an audio-oscillator 184 is connected by way of the lead 186 to the output of the signal detector .116, thus upon the detection of the frequency of 941 Hz, the output signal from that detector 116 energizes the audio-oscillator causing a signal to. be applied therefrom to its output 188. The output 188 may then be connected to a loud speaker 190 which is located adjacent an attendant where the dictating equipment is located indicating that some subscriber has completed dictation and is ready for the recording media to be replaced, desires transcription of the dictation, desires to speak with the attendant, or the like. In addition, appropriate circuitry may be utilized to connect an output from the audio-oscillator over the lead 192 to the input at 134 as previously described in conjunction with FIG. 2.
From the foregoing, it will become apparent to those skilled in the art that upon the receipt of a 697 Hz signal with the common signal of 1,209 Hz, the record detector 110 detects the same and produces an output signal on the lead 118. Such output signal causes the record flip-flop 140 to provide an output signal on the lead 146 which energizes the record relay 148 which then causes the appropriate apparatus in the dictating equipment to place the same in a record mode. Thereafter the subscriber speaks into the handpiece of the telephone and his voice is received and recorded on the recording medium of the dictating equipment. Simultaneously the record detector output signal on lead 118 is applied and passed through the OR gate 158 to the run flip-flop 164 causing an output signal to ap- 48 to the amplifier 50, the output of which is applied by the lead 52 to the common frequency detector 12 and by the lead 54 to the terminal 56 of a normally open movable contact 58 of a reed relay 60. Simultaneously, the signal-pair are also applied over the lead 62 to the terminal 64 of the movable contact 66 of the reed relay 68.
The common frequency detector 12 may be any type of frequency detector desired which is capable of receiving and detecting the presence of the common signal 1,209 Hz and providing an output signal in response thereto. Preferably, the common frequency detector in accordance with the present invention is a phase-locked loop integrated semiconductor circuit having appropriate external components connected thereto to cause it to be sensitive to a signal of 1,209 Hz. Such integrated circuits are well known in the art and one such circuit which has been found to be appropriate is manufactured by Signetics Corporation, Sunnyvale, California and is identified by the number NE567V and is described in a bulletin entitled Tone Decoder, copyright 1970 by Signetics Corporation. Such a device is constructed on a 57 X 61 mil semiconductor chip and contains 62 transistors and 50 resistors interconnected in such a fashion as to provide a phaselocked loop together with a lock detector and output amplifier. When a signal within the capture range of the loop-is present, the loop locks to that signal. Once lock has occurred, the lock-detector voltage responds driving the output amplifier. The output amplifier applies base current to the output transistor, the collector of which may be externally connected to the desired load. The center frequency of the detection band is determined by the free-running frequency of the controlled oscillator in the loop. The width of the detection band, which is equal to the loop-capture range is a predictable function of the internal and external connected components and the input signal amplitude.
From the foregoing description, it will now be apparent that the incoming control signal comprising the signal-pair having frequencies of 697 Hz and l,209 Hz, amplified by the amplifier 50 to provide the proper amplitude signal, is applied to the input of the common frequency detector 12 by lead 52. Since the integrated circuit and external components connected thereto are sensitive to 1,209 Hz, the detector 12 drives the output transistor 70 (which is included as part of the integrated circuit) to saturation. As is illustrated, the collector of the transistor 70 is connected through load resistor 72 to the positive terminal of the voltage source 74. Also connected to the positive terminal of the voltage source 74 through the load resistor 72 is the coil 76 of the reed relay 68 the other terminal of which is connected to ground or common as shown.
Prior to the transistor 70 being driven to saturation, it was cut off and therefore the full potential of the voltage source 74 was applied to the coil 76 thus energizing the reed relay 68 and causing the movable contact 66 to be in contact with the stationary contact 78 which is connected by the lead 80 to the dictating equipment. Thus any signals appearing upon the line 62 which were transmitted by way of the telephone system above described would be applied through the reed relay 68 closed contacts to the dictating equipment record section-34. However, upon detection of the 1,209 Hz common signal and the transistor going to saturation, the collector of the transistor 70 is effectively connected to ground through the transistor thus causing the point 82 to be effectively connected to ground. Such saturated conduction of the transistor 70 thus removes the potential from the coil 76 which opens the movable contact 66 of the reed relay 68 thereby precluding transmission of any information to the dictating equipment over the lead 80. Upon cessation of the common signal of the signal-pair, the transistor 70 again becomes noncon ducting and the voltage from the source 74 is applied to v the coil 76 and the reed relay is again energized thus completing the circuit through the closed contacts thereof. It can thus be seen that the reed relay 68 effectively functions as a gate which is closed at all times except during the presence of the common signal of the signal-pair, in this example having the frequency 1,209 Hz. During the presence of such common signal, the gate is the open. The opening of the gate thus prevents the recording on the recording medium of the dictating equipment of any of the control frequencies which are transmitted over the telephone system.
Also connected to the point 82 is a series connection of a diode 84 and capacitor 86 having the common point 88 therebetween, the capacitor 86 also being connected to ground. A base resistor 90 is connected between the common point 88 and the base of transistor 92. The emitter 94 of the transistor 92 is connected to ground while the collector 96 thereof is connected to a common point 104. A load resistor 98 is connected from point 104 to the positive terminal of the source of potential 74'. One terminal of the coil 102 of the reed relay 60 is also connected to the common point 104, the other terminal being connected to ground as shown. When there is no common frequency signal being detected by the detector 12 and thus the transistor 70 is nonconducting, the positive terminal of the source 74 is connected through the resistor 72 to the anode of the diode 84 thereby causing the diode 84 to be forward-biased and thus conducting. Current flow through the diode 84 results in a charge being assumed by the capacitor 86, positive with respect to ground, thereby to forward-bias the emitter-base diode of the transistor 92 causing the transistor 92 to become conducting in a saturated state. As a result, since the emitter 94 is connected to ground, the point 104 is effectively connected to ground through the transistor 92 and thus the coil 102 of the reed relay 60 is de-energized thereby causing the movable contact 58 to be separated from the stationary contact 106 as shown.
Upon detection of the 1,209 Hz common signal and the transistor 70 becoming conducting, thus causing the point 82 to be effectively connected to ground, the diode 84 becomes reverse-biased from the charge on capacitor 86. The charge on the capacitor 86 retains the transistor 92 conducting until the capacitor 86 is substantially discharged through the resistor 90 and the emitter-base diode of the transistor 92 which causes the transistor 92 to become nonconducting. When the transistor 92 becomes nonconducting, the positive terminal of the voltage source 74 is then connected through the resistor 98 to the coil 102 of the reed relay 60 thereby energizing the same and causing the movable contact 58 to move into engagement with the stationary contact 106 thus completing the circuit from pear and energize the run relay. Thus, the appropriate mechanism in the dictating equipment is caused to i move the magnetic recording medium relative the record head as is well known.
In the event a 770 Hz signal is received with the common signal of 1,209 Hz, the play backup detector 112 provides an output signal which is connected to the terminal 144 of the record flip-flop 140 causing a signal to appear on the terminal 150 thereof which is applied to the NAND gate 152. Simultaneously the signal is applied to the OR gate 158 and is applied in turn to the terminal 162 of the run flip-flop 164 causing an output signal to appear on terminal 168 thereof which energizes the run relay 170. The signals appearing at the terminals 150 and 168 of the flip flops 140 and 164 respectively energize and pass through the NAND gate 152 causing the play lamp 154 to become energized. Simultaneously, the play backup relay 180 is energized thus setting in motion in the dictating equipment the appropriate apparatus to cause the dictating equipment to respond to the desires of the subscriber. If the button 4 on the Touch-Tone telephone or the tone generator 28 is depressed momentarily, the magnetic recording medium will back up momentarily and then play so that a review of the immediately preceding recorded material on the tape can be had. If a further review is desired, the subscriber depresses button 4 and holds the same depressed for the desired period of time all during which the magnetic recording medium is rewound. Upon release of the button, the dictating equipment goes into the play mode and the subscriber is able to hear over the telephone system what has been recorded on the recording medium. When it is desired to stop, button 7 is depressed and the detector 114 detects the 852 Hz signal received with the common signal of 1,209 Hz and provides an output signal on lead 122 which is connected to terminal 166 of the run flip-flop 164 thus causing an output signal to appear on the terminal 174 which illuminates the stop lamp 176. Simultaneously the signal appearing at the terminal 168 of the run flip-flop 164 is removed thus deenergizing the run relay 170. This causes the dictating equipment to stop moving the recording medium and an audible signal is then heard by the subscriber indicating that the dictating equipment has stopped and any additional instructions he desires to give such as record or the like may then be imparted to the dictating equipment as above described. Depression of the button generates a 941 Hz signal with the common signal of 1,209 Hz which is detected by the detector 1 16 and energizes the not-run section of the run flip-flop 164 precisely as did depression of button 7 or the stop signal. The same results flow but in addition the audible signals are generated as above described.
The interconnection of the various lamps and relays to the dictating equipment may be accomplished by utilization of the leads 194, 196, 198, 200 and 202 I which may be interconnected to appropriate cabling or 1. Apparatus for effecting remote control of elec tronic equipment where intelligence and control signals are transmitted over the same transmission path comprising:
generator means remote from said equipment for generating a plurality of control signals each having a constant frequency pair of signals, one of said signal-pair being common to all of said plurality of signals;
interface means interconnecting said generator means and said equipment for transmitting intelligence and control signals to said equipment, said interface means including:
1. first means responsive only to said one of said signal-pair for precluding application of any control or intelligence signals to any recording media during the presence of said one of said signal-pair,
2. a plurality of second means each responsive only to the other of said signal-pair of said control signals for effecting desired control of said equipment.
2. Apparatus as defined in claim 1 which further includes time-delay means responsive to said first means for precluding application of said other of said signalpair to said second means for a predetermined period of time after application of said common one of said signal-pair.
3. Apparatus as defined in claim 1 wherein said generator means is a portable means connectable to a telephone system.
4. Apparatus as defined in claim 1 wherein said generator means is at least one Touch-Tone telephone.
5. Apparatus as defined in claim 1 wherein said first means includes a first detector for said one of said signal-pair, switch means connected in the transmissionpath to said recording media, said switch means being connected to said first detector for opening said switch means during the presence of said one of said frequency pair.
6. Apparatus as defined in claim 5 wherein said first detector is a phase-locked loop.
7. Apparatus as defined in claim 1 wherein each of said plurality of second means includes a second detector, each said second detector being sensitive only to a signal having a predetermined frequency which is different from each of said other of said signal-pairs.
8. Apparatus-as defined in claim 7 wherein each of said plurality of second detectors is a phase-locked loop.
9. Apparatus as defined in claim 1 wherein said interface means further includes second switch means in the transmission path to the control section of said equipment for controlling application of said other of said signal-pairs to said second means only during the presence of said common one of said signal-pair.
10. Apparatus as defined in claim 9 which further includes time-delay means precluding operation of said second switch means until said common one of said signal-pair is present for a predetermined period of time.
11. Apparatus for effecting remote control of electronic equipment for receiving and recording information and control signals transmitted over telephone lines said control signals each including first and second signals of different frequencies with one of said first and second signals having a constant frequency means connecting the input terminal of said common frequency signal detector to said telephone line for receiving all signals applied thereto; and
means connecting the output terminal of said common frequency signal detector to said first and second switch means for opening said first switch means and closing said second switch means during the presence of said common frequency signal.
12. Apparatus as defined in claim 11 wherein said first and second switch means are reed relays.