CA1049616A - Tone calling with single sideband radio equipment - Google Patents
Tone calling with single sideband radio equipmentInfo
- Publication number
- CA1049616A CA1049616A CA206,828A CA206828A CA1049616A CA 1049616 A CA1049616 A CA 1049616A CA 206828 A CA206828 A CA 206828A CA 1049616 A CA1049616 A CA 1049616A
- Authority
- CA
- Canada
- Prior art keywords
- signal
- tone
- frequency
- audio
- tones
- 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
Links
Classifications
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04W—WIRELESS COMMUNICATION NETWORKS
- H04W88/00—Devices specially adapted for wireless communication networks, e.g. terminals, base stations or access point devices
- H04W88/18—Service support devices; Network management devices
- H04W88/185—Selective call encoders for paging networks, e.g. paging centre devices
- H04W88/188—Selective call encoders for paging networks, e.g. paging centre devices using frequency address codes
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
- H04B1/06—Receivers
- H04B1/16—Circuits
- H04B1/30—Circuits for homodyne or synchrodyne receivers
- H04B1/302—Circuits for homodyne or synchrodyne receivers for single sideband receivers
Landscapes
- Engineering & Computer Science (AREA)
- Computer Networks & Wireless Communication (AREA)
- Signal Processing (AREA)
- Mobile Radio Communication Systems (AREA)
Abstract
ABSTRACT OF THE DISCLOSURE
Tone calling equipment for radio telephones employing a single sideband radio frequency transmitter to transmit a double tone signal comprising two precisely spaced side tones. These side tones are at frequencies fc + f1 and fc - f1, produced by modulating an audio tone f1 on a subcarrier audio signal at fc. The two side tones are modulated by a single sideband transmitter onto a radio frequency (RF) signal and are then both transmitted. At a single sideband RF receiver, the two side tones are received as an RF signal. The absolute value of this signal may vary, but the two side tones are separated by precisely 2f1. The difference 2f1 between the two side tones is detected, thus eliminating the variable errors which may be present in the detected signal, and enabling the use of a very narrow filter. This filter passes the signal 2f1 to provide an output audio tone which actuates, for example, telephone ringing apparatus.
Tone calling equipment for radio telephones employing a single sideband radio frequency transmitter to transmit a double tone signal comprising two precisely spaced side tones. These side tones are at frequencies fc + f1 and fc - f1, produced by modulating an audio tone f1 on a subcarrier audio signal at fc. The two side tones are modulated by a single sideband transmitter onto a radio frequency (RF) signal and are then both transmitted. At a single sideband RF receiver, the two side tones are received as an RF signal. The absolute value of this signal may vary, but the two side tones are separated by precisely 2f1. The difference 2f1 between the two side tones is detected, thus eliminating the variable errors which may be present in the detected signal, and enabling the use of a very narrow filter. This filter passes the signal 2f1 to provide an output audio tone which actuates, for example, telephone ringing apparatus.
Description
1~ L?~9 6~
~le present invention relates to tone calling equipment employ-ing single sideband radio transmission.
There exists a need for tone calling equipment capable of calling or "ringing" remote radio telephones and employing single sideband transmission.
If an audio tone is modulated, in a single sideband trans-mitter, on a carrier frequency, and the resulting modulated signal i9 trans-mitted and detected and demodulated by a single sideband receiver, it is found in practice that, employing an audio tone having a typical frequency 10 of 100 Hz, the output of the receiver has a potential variation of + 30 Hz.
Consequently, narrow audio tone filters cannot be employed to filter the output of the single sideband receiver, and the system is therefore im-practical.
Accordingly, it is an object of the present invention to provide tone calling equipment employing a single sideband transmitter in which the above-mentioned disadvantage is mitigated or even entirely over--`~ come.
According to one aspect of the present invention, there is pro-vided for use in tone calling equipment the improvement consisting essentially 20 of means for generating an audio frequency tone signal; means for generating - a subcarrier signal at another audio frequency; means for modulating the -audio frequency tone signal on the subcarrier signal to produce a double tone signal comprising two tones having a separation of a multiple of the audio tone signal frequency; and a single sideband transmitter for modulating and transmitting the double tone signal as a radio frequency signal.
According to another aspect of the invention, there is provided for use in tone calling equipment, the improvement consisting essentially of a single sideband receiver for detecting a transmitted radio frequency ; double tone signal having two tones therein, the two tones being separated ~ ~`
30 by a multiple of a predetermined audio tone signal frequency; an amplitude detector means connected to an output of the receiver means to detect the multiple of the predetermined audio tone frequency signal; a tone filter -- 1 -- .
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means connected to an output of the amplltude detector means; and actuator means responsive to the output from the tone filter means to provide an output si~nal.
By yet another aspect of this invention there is provided a method of tone calling in which an audio signsl is transmitted from one location to another location, consisting essentially of; (a) generating an audio signal at audio frequency fl; (b) generating a subcarrier signal at another audio frequency fc; (c) modulating the audio signal fl on the sub-carrier signal f to produce two tones (fc + fl) and (fc ~ fl), the two tones being separated by a frequency differential of precisely multiple of the audio signal frequency; (d) generating a transmission signal at a radio frequency by modulating the two tones (fc + fl) and (fc ~ fl) on a carrier signal at the radio frequency; (e) transmitting the transmission signal from the one to the other location; and (f) demodulating the trans-mission signal received at the other location to extract therefrom the multiple of the audio signal frequency for actuating audio tone calling apparatus.
The invention will be more readily understood from the follow-ing description. That description is to be read in conjunction with the accompanying drawing, which shows by way of example, a block diagram of a - tone calling equipment embodying this invention~
The equipment illustrated in the drawing has an audio tone generator 10 for generating an audio tone at frequency fl, and a subcarrier generator for generating a subcarrier at another audio frequency fc. The audio tone generator 10 is conventional in structure and function, and typically, is a precision waveform generator, Intersil ôO38 having inte-grated circuits~ The subcarrier generator 11 (oscillator) is also conven-tional in structure and operation, typically being an Intersil 8083 with integrated circuits.
The outputs of the audio tone generator 10 and the subcarrier generator 11 are connected to respective inputs of a double sideband
~le present invention relates to tone calling equipment employ-ing single sideband radio transmission.
There exists a need for tone calling equipment capable of calling or "ringing" remote radio telephones and employing single sideband transmission.
If an audio tone is modulated, in a single sideband trans-mitter, on a carrier frequency, and the resulting modulated signal i9 trans-mitted and detected and demodulated by a single sideband receiver, it is found in practice that, employing an audio tone having a typical frequency 10 of 100 Hz, the output of the receiver has a potential variation of + 30 Hz.
Consequently, narrow audio tone filters cannot be employed to filter the output of the single sideband receiver, and the system is therefore im-practical.
Accordingly, it is an object of the present invention to provide tone calling equipment employing a single sideband transmitter in which the above-mentioned disadvantage is mitigated or even entirely over--`~ come.
According to one aspect of the present invention, there is pro-vided for use in tone calling equipment the improvement consisting essentially 20 of means for generating an audio frequency tone signal; means for generating - a subcarrier signal at another audio frequency; means for modulating the -audio frequency tone signal on the subcarrier signal to produce a double tone signal comprising two tones having a separation of a multiple of the audio tone signal frequency; and a single sideband transmitter for modulating and transmitting the double tone signal as a radio frequency signal.
According to another aspect of the invention, there is provided for use in tone calling equipment, the improvement consisting essentially of a single sideband receiver for detecting a transmitted radio frequency ; double tone signal having two tones therein, the two tones being separated ~ ~`
30 by a multiple of a predetermined audio tone signal frequency; an amplitude detector means connected to an output of the receiver means to detect the multiple of the predetermined audio tone frequency signal; a tone filter -- 1 -- .
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~... ~1 : ~
~049~
means connected to an output of the amplltude detector means; and actuator means responsive to the output from the tone filter means to provide an output si~nal.
By yet another aspect of this invention there is provided a method of tone calling in which an audio signsl is transmitted from one location to another location, consisting essentially of; (a) generating an audio signal at audio frequency fl; (b) generating a subcarrier signal at another audio frequency fc; (c) modulating the audio signal fl on the sub-carrier signal f to produce two tones (fc + fl) and (fc ~ fl), the two tones being separated by a frequency differential of precisely multiple of the audio signal frequency; (d) generating a transmission signal at a radio frequency by modulating the two tones (fc + fl) and (fc ~ fl) on a carrier signal at the radio frequency; (e) transmitting the transmission signal from the one to the other location; and (f) demodulating the trans-mission signal received at the other location to extract therefrom the multiple of the audio signal frequency for actuating audio tone calling apparatus.
The invention will be more readily understood from the follow-ing description. That description is to be read in conjunction with the accompanying drawing, which shows by way of example, a block diagram of a - tone calling equipment embodying this invention~
The equipment illustrated in the drawing has an audio tone generator 10 for generating an audio tone at frequency fl, and a subcarrier generator for generating a subcarrier at another audio frequency fc. The audio tone generator 10 is conventional in structure and function, and typically, is a precision waveform generator, Intersil ôO38 having inte-grated circuits~ The subcarrier generator 11 (oscillator) is also conven-tional in structure and operation, typically being an Intersil 8083 with integrated circuits.
The outputs of the audio tone generator 10 and the subcarrier generator 11 are connected to respective inputs of a double sideband
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suppressed carrier modulator 12. The output of the modulator 12 is con-nected to a single sideband transmitter 13 having an aerial 14.
The double sideband suppressed carrier modulator 12 is also conventional. Typically, the modulator 12 is a Motorola MC 1596 balanced modulator, again using an integrated circuit. Such a device is well known both in structure and operation to persons skilled in the communications art.
It will, of course, be evident that to transmit the modulated audio signal, it must be modulated onto radio frequencies. These radio frequency signals are transmitted from the aerial 14.
The signal transmitted at radio frequencies by the single - side-band transmitter 13 is picked up by a receiver aerial 15 of a single sideband receiver 16. Again, reception of the transmitted signal is at radio frequencies, as will be evident to the reader.
The audio output of the single sideband receiver 16 is connected to the input of an amplitude detector 17. The output of the amplitude detector 17 is connected, in turn, through a tone filter, (not shown) to actuating means, for example, in the form of telephone ringing apparatus. The tone filter is operative to pass the signal desired, i.e., a tone at precisely twice the original tone frequency fl. The single sideband transmitter 13, and the ;
receiver 16 are both conventional in structure and operation. Typically, ~hese are a Collins Radio Transceiver, Model 618T. The amplitude detector 17 is also conventional, for example, Model No. SN 52741 of Texas Instruments, an integrated circuit, with diode feedback.
; The operation of the above-described equipment is as follows~
The audio tone signal at audio frequency fl, and the sub-carrier signal at another audio frequency fc are generated in the audio generator 10 and the subcarrier generator 11, respectively. These two ~ signals are applied to the modulator 12. There, the audio tone signal at fl, which is typically 100 H~, is modulated on -the subcarrier signal at f , which is typically 1000 H~, to produce two side tones (fc ~ fl) typically MR/
_ . , .. ,. .,, _ _ .. _, . . ~ _, . , _ _ _ . _ . . .
. . -1049~L6 900 Hz, and (fc + fl)~ typically 1100 ~Iz~ Thus, a modulated, double tone signal having 8 precise separation of 2fl (typically 200 Hz) is formed.
This double tone signal is then applied to the single sideband transmltter 130 This double tone signal containing the side tones (fc ~ fl) and (fc ~ fl) is modulated on a carrier signal at radio frequency and trans-mitted from the aerial 14. Transmission, of course, is at radio frequencies.
The transmitted signal is received by the single sideband receiver 16 and is demodulated, for subsequent processing. This, of course, is conventional practice. The demodulated output from the single sideband receiver 16 is a signal having two tones whose absolute values may vary by - 30 Hz, but whose separation is precisely 2fl. These two tones are st frequencies of (fc ~ fl + af) and (fc ~ fl + ~f), where ~ f represents a variable error in the received signal. As mentioned above that can be in the order of + 30 Hz.
The amplitude detector 17 detects the difference in frequencies between these two tones in the output signal from the receiver 16. Thus, - the amplitude detector 17 provides an output which is precisely 2fl, as will be seen from the preceeding paragraph~ In other words, this output signal can be filtered and passed by a very narrow filter which passes only the frequency difference detected, i.e~, 2fl, which is an audio frequency output signal. That audio signal can then operate an actuating device, such =s the telephone ringing =pp=ratuo mentioned e=rlier.
.
.;
; 30 MR/
, . . .
.: :
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. ::- .. ..
. .
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suppressed carrier modulator 12. The output of the modulator 12 is con-nected to a single sideband transmitter 13 having an aerial 14.
The double sideband suppressed carrier modulator 12 is also conventional. Typically, the modulator 12 is a Motorola MC 1596 balanced modulator, again using an integrated circuit. Such a device is well known both in structure and operation to persons skilled in the communications art.
It will, of course, be evident that to transmit the modulated audio signal, it must be modulated onto radio frequencies. These radio frequency signals are transmitted from the aerial 14.
The signal transmitted at radio frequencies by the single - side-band transmitter 13 is picked up by a receiver aerial 15 of a single sideband receiver 16. Again, reception of the transmitted signal is at radio frequencies, as will be evident to the reader.
The audio output of the single sideband receiver 16 is connected to the input of an amplitude detector 17. The output of the amplitude detector 17 is connected, in turn, through a tone filter, (not shown) to actuating means, for example, in the form of telephone ringing apparatus. The tone filter is operative to pass the signal desired, i.e., a tone at precisely twice the original tone frequency fl. The single sideband transmitter 13, and the ;
receiver 16 are both conventional in structure and operation. Typically, ~hese are a Collins Radio Transceiver, Model 618T. The amplitude detector 17 is also conventional, for example, Model No. SN 52741 of Texas Instruments, an integrated circuit, with diode feedback.
; The operation of the above-described equipment is as follows~
The audio tone signal at audio frequency fl, and the sub-carrier signal at another audio frequency fc are generated in the audio generator 10 and the subcarrier generator 11, respectively. These two ~ signals are applied to the modulator 12. There, the audio tone signal at fl, which is typically 100 H~, is modulated on -the subcarrier signal at f , which is typically 1000 H~, to produce two side tones (fc ~ fl) typically MR/
_ . , .. ,. .,, _ _ .. _, . . ~ _, . , _ _ _ . _ . . .
. . -1049~L6 900 Hz, and (fc + fl)~ typically 1100 ~Iz~ Thus, a modulated, double tone signal having 8 precise separation of 2fl (typically 200 Hz) is formed.
This double tone signal is then applied to the single sideband transmltter 130 This double tone signal containing the side tones (fc ~ fl) and (fc ~ fl) is modulated on a carrier signal at radio frequency and trans-mitted from the aerial 14. Transmission, of course, is at radio frequencies.
The transmitted signal is received by the single sideband receiver 16 and is demodulated, for subsequent processing. This, of course, is conventional practice. The demodulated output from the single sideband receiver 16 is a signal having two tones whose absolute values may vary by - 30 Hz, but whose separation is precisely 2fl. These two tones are st frequencies of (fc ~ fl + af) and (fc ~ fl + ~f), where ~ f represents a variable error in the received signal. As mentioned above that can be in the order of + 30 Hz.
The amplitude detector 17 detects the difference in frequencies between these two tones in the output signal from the receiver 16. Thus, - the amplitude detector 17 provides an output which is precisely 2fl, as will be seen from the preceeding paragraph~ In other words, this output signal can be filtered and passed by a very narrow filter which passes only the frequency difference detected, i.e~, 2fl, which is an audio frequency output signal. That audio signal can then operate an actuating device, such =s the telephone ringing =pp=ratuo mentioned e=rlier.
.
.;
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Claims (6)
IS CLAIMED ARE DEFINED AS FOLLOWS:
1. In tone calling equipment, the improvement consisting essentially of:
means for generating an audio frequency tone signal;
means for generating a subcarrier signal at another audio frequency;
means for modulating said audio frequency tone signal on said subcarrier signal to produce a double tone signal comprising tones having a separation of a multiple of said audio tone signal frequency; and a single sideband transmitter for modulating and transmitting said double tone signal as a radio frequency signal.
means for generating an audio frequency tone signal;
means for generating a subcarrier signal at another audio frequency;
means for modulating said audio frequency tone signal on said subcarrier signal to produce a double tone signal comprising tones having a separation of a multiple of said audio tone signal frequency; and a single sideband transmitter for modulating and transmitting said double tone signal as a radio frequency signal.
2. In tone calling equipment, the improvement consisting essentially of:
a single sideband receiver for detecting a transmitted radio frequency double tone signal having two tones therein, the two tones being separated by a multiple of a predetermined audio tone signal frequency;
an amplitude detector means connected to an output of the receiver to detect the multiple of said predetermined audio tone signal frequency;
a tone filter means connected to an output of the amplitude detector means; and actuator means responsive to the output from said tone filter means to provide an output signal.
a single sideband receiver for detecting a transmitted radio frequency double tone signal having two tones therein, the two tones being separated by a multiple of a predetermined audio tone signal frequency;
an amplitude detector means connected to an output of the receiver to detect the multiple of said predetermined audio tone signal frequency;
a tone filter means connected to an output of the amplitude detector means; and actuator means responsive to the output from said tone filter means to provide an output signal.
3. The invention defined in claim 1 wherein there is further provided the combination defined in claim 2.
4. Tone calling equipment for processing a selected tone signal of a predetermined audio frequency f1 consisting essentially of:
first generating means to produce said tone signal at f1;
second generating means to produce a subcarrier signal at another audio frequency fc;
means for modulating said signal f1 on the subcarrier signal fc to produce a double tone signal comprising two side tones of (fc - f1) and (fc + f1), said side tones having a frequency separation of 2f1, the means for modulating being connected to said first and second generating means, single sideband transmitting means for modulating said side tones onto a transmitter signal at a radio frequency and transmitting said R.F. signal;
single sideband receiver means to detect the transmitter signal containing the two side tones (fc - f1) and (fc + f1);
amplitude detector means connected to an output of the receiver means to detect said double tone signal;
tone filter means connected to the amplitude detector means to pass a tone having a frequency equal to the difference in frequency between said double tone signal being 2f1; and actuator means responsive to the output from said tone filter means to provide an output signal.
first generating means to produce said tone signal at f1;
second generating means to produce a subcarrier signal at another audio frequency fc;
means for modulating said signal f1 on the subcarrier signal fc to produce a double tone signal comprising two side tones of (fc - f1) and (fc + f1), said side tones having a frequency separation of 2f1, the means for modulating being connected to said first and second generating means, single sideband transmitting means for modulating said side tones onto a transmitter signal at a radio frequency and transmitting said R.F. signal;
single sideband receiver means to detect the transmitter signal containing the two side tones (fc - f1) and (fc + f1);
amplitude detector means connected to an output of the receiver means to detect said double tone signal;
tone filter means connected to the amplitude detector means to pass a tone having a frequency equal to the difference in frequency between said double tone signal being 2f1; and actuator means responsive to the output from said tone filter means to provide an output signal.
5. A method of tone calling in which an audio signal is trans-mitted from one location to another location consisting essentially of:
(a) generating an audio signal at audio frequency f1;
(b) generating a subcarrier signal at another audio frequency fc;
(c) modulating the audio signal f1 on the subcarrier signal fc to produce two tones (fc + f1) and (fc - f1), said two tones being separated by a frequency differential of precisely a multiple of said audio signal frequency;
(d) generating a transmission signal at a radio frequency by modulating said two tones (fc + f1) and (fc - f1) on a carrier signal at said radio frequency;
(e) transmitting said transmission signal from said one to said other location; and (f) demodulating the transmission signal received at said other location to extract therefrom the multiple of said audio signal frequency for actuating audio tone calling apparatus.
(a) generating an audio signal at audio frequency f1;
(b) generating a subcarrier signal at another audio frequency fc;
(c) modulating the audio signal f1 on the subcarrier signal fc to produce two tones (fc + f1) and (fc - f1), said two tones being separated by a frequency differential of precisely a multiple of said audio signal frequency;
(d) generating a transmission signal at a radio frequency by modulating said two tones (fc + f1) and (fc - f1) on a carrier signal at said radio frequency;
(e) transmitting said transmission signal from said one to said other location; and (f) demodulating the transmission signal received at said other location to extract therefrom the multiple of said audio signal frequency for actuating audio tone calling apparatus.
6. The method defined in claim 5, wherein the multiple is 2.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA206,828A CA1049616A (en) | 1974-08-12 | 1974-08-12 | Tone calling with single sideband radio equipment |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA206,828A CA1049616A (en) | 1974-08-12 | 1974-08-12 | Tone calling with single sideband radio equipment |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1049616A true CA1049616A (en) | 1979-02-27 |
Family
ID=4100877
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA206,828A Expired CA1049616A (en) | 1974-08-12 | 1974-08-12 | Tone calling with single sideband radio equipment |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA1049616A (en) |
-
1974
- 1974-08-12 CA CA206,828A patent/CA1049616A/en not_active Expired
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKEX | Expiry |
Effective date: 19960227 |