MXPA96004492A - Apparatus for simultaneous communications of voice / data at high speed - Google Patents

Abstract

The present invention relates to: a high-speed modem for simultaneously transmitting voice frequency signals and pre-coded digital data signals on a single communication channel. The modem is operable to combine a voice frequency signal with a pre-coded digital data signal for transmission at high speeds, high energy levels and low distortion previously achievable by high speed data only modems. The speech frequency signal is processed using conventional data processing techniques to produce a speech frequency signal and a control signal containing information related to the encoding of the speech frequency signal. The control signal is multiplexed and displayed for transmission with the digital data. The selected bits of the multiplexed data are used to define the rotation of the digital data and to rotate or rotate the speech frequency vector. The digital data is precoded to compensate and minimize the noise in the communication channel. The vocal frequency vector that was rotated and the precoded digital data are then combined and transmitted. At a remote location, the transmitted signal is received by the receiving modem and is filtered and separated to thereby recover the individual encoded signals. The separation of the coded frequency signal from the precoded digital data signal is effected before the reconstruction of the precoded digital data signal. Then the rotation of the coded voice frequency signal is reversed. The encoded voice frequency and precoded digital data signals are then individually decoded to recover the data voice frequency signals that originated in the transmit modem.

Description

OR AT HIGH SPEED FIELD OF INVENTION The present invention relates to high-speed modems that incorporate data precoding and, more particularly, to such modems that operate for the transmission and reception of simultaneous voice / data signals.

BACKGROUND OF THE INVENTION High-speed data modems, well known in the art, are operated to transmit data at signal transmission rates of up to 28, 800 bits per second over the general switched telephone network and in circuits of the double-wired telephone type. to point. High-speed data modems are described in ITU-T Recommendation V.34, entitled "Data Communication on the Telephone Network", presented to the telecommunication standardization sector of the International Telecommunication Union in September 1994. To obtain these high transmission rates, a transmitter of such modems includes a precoder that can be operated to minimize (blanking) or compensate for noise in the communications channel that may affect the signal transmitted at such high speeds. REF: 22984 A receiver in a second modem that receives the transmission must include the necessary circuits to reconstruct the precoded signal. The precoding of the data signals thus allows to achieve high data transmission rates at high energy levels and to reduce distortion of the signals. However, these high-speed modems are unable to transmit and / or receive transmissions of voice and data signals simultaneously. However, it is known how to simultaneously transmit voice and data signals along a simple communication line, such as an analog telephone channel. The transmission of simultaneous voice / data signals is done through specially constructed modems to transmit and receive such simultaneous signals. However, these modems are unable to transmit simultaneous voice / data signals at the high energy rates and low distortion achievable by a modem that incorporates the precoding of the data signal. Thus, it would be desirable to provide a high speed simultaneous voice / data modem that incorporates data precoding and that is capable of maintaining the previous power levels and decreasing the distortion achievable by conventional simultaneous voice / data modems.

BRIEF DESCRIPTION OF THE INVENTION The teachings of the present invention allow the transmission of simultaneous voice and data signals in a high speed modem, ie at transmission speeds up to (and potentially beyond) 28,000 bits per second, while maintaining the levels of previous energy and low signal distortion that is achievable by conventional simultaneous voice / data modems, known above. To achieve this goal, the analog voice frequency signals entering the modem are encoded according to the known procedures to produce speech frequency vector signals and control signals, while the digital data signals that are input to the modem, for example. example by a user, they are pre-coded before the coding of the digital data and the combination with the voice frequency signal for transmission. A modem (modulator-demodulator) constructed in accordance with the invention includes an intermediate circuit first in first output (FIFO), which accepts as its input both the control signal produced during the coding of the analog voice frequency signal and the signal of digital data, and multiplexes those signals. The multiplexed data is then fed to either a mapping device, a device for mapping a frame or a differential encoder. The data is represented and rotated in the device for mapping and the data that is fed through the differential encoder to the device for mapping, together with certain data fed directly to the device for mapping and a feedback bit introduced to the device for mapping, are selected as representative bits to define or represent the rotation of the data signals represented. After passing through the mapping device, the multiplexed data is precoded to reduce and compensate for the noise effects that may be picked up by the signal during transmission. The selected representative data bits defining the rotation of the digital data signals represented are fed directly to a rotator in which they are combined with the vector voice frequency signals. The analog voice frequency signal is coded, before being input or fed to the rotator, according to conventional coding techniques as mentioned herein. The rotator operates to rotate the vector signal of speech frequency according to the rotation defined by the selected representative data bits. The rotated vocal frequency vector signal may also be pre-coded or pre-emphasized to improve the frequency response of the signal and to compensate for filtering in the remote receiving modem. The digital data signal is precoded and speech signal cranked are then combined in an adder and fed to a non-linear encoder, which encodes the combined signal using conventional techniques transmission to a remote rrodem along and through a communication channel. The combined signal transmitted through the communication channel is received by the remote modem. The received combined signal is demodulated, compensated or equalized and decoded in a non-linear manner. The speech frequency vector signal and the precoded digital data signal are then filtered and separated, and the precoded digital data signal is reconstructed according to the precoding techniques used in the transmitter to obtain the original traced signals. The vector vocal frequency signals are rotated to their original state according to a control signal received from the circuit that reconstructs the precoded digital data signal. The tracked digital data signals are then decoded to recover the original digital data signal received in or fed into the transmitter modem. The vector speech-frequency signals that were rotated to their original state are also decoded according to the coding techniques used in the transmitter to thereby retrieve the original analogue vocal frequency signal received in the transmitter modem. Other objects and features of the invention will be apparent from the following detailed description considered in conjunction with the accompanying drawings. It should be understood, however, that the drawings are designed solely for purposes of illustration and not as a definition of the limits of the invention, for which reference should be made to the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS In the drawings, in which like reference numerals denote similar elements throughout the different views: Figure 1 is a block diagram of a transmitter of a simultaneous voice / data modem constructed in accordance with the present invention; Figure 2 is a block diagram of a circuit for pre-emphasizing the speech frequency vector signal for use with the transmitter of Figure 1; Figure 3 is a block diagram of a receiver of a simultaneous voice / data modem constructed in accordance with the present invention; Figure 4 is a block diagram of a filter for compensating the speech frequency vector signal after separation of the precoded digital data signal for use in the receiver of Figure 3; Figure 5 is a graphic representation of the signal produced by the device for mapping; Figure 6 is a graphic representation of a precoded digital data signal; Figure 7 is a graphic representation of the combined voice and data signals for transmission in accordance with the present invention; and Figure 8 is a graphic representation of a combined voice and data signal after reception and filtering in the receiver of the invention.

DETAILED DESCRIPTION OF THE PREFERRED MODALITIES The present invention will now be described with particular reference to the drawings. Figure 1 describes a transmitter arrangement or portion of a simultaneous voice / data modem according to the present invention and identified by the general reference number 100. Both the analog voice frequency and digital data signals are input to a digital modem. origin, for example, by a user. The analog voice frequency signal is processed in an encoder 101, as, for example, in accordance with conventional coding techniques to produce a vector voice frequency signal, a digital voice frequency control signal that provides information related to the coding of the speech. analog voice frequency signal. The digital data signal input by the user and the speech frequency control signal are applied to a first first-in, first-out (FIFO) intermediate circuit 102, in which the signals are multiplexed and from which certain predetermined bits of the multiplexed signals are fed to a respective one of a device for mapping frames 104, a differential encoder 106, or a device for mapping 108. The predetermined selection of which of the bits of the multiplexed data are directed to which of such devices it is not critical since the routing is consistent or standardized throughout the industry (or at least for the transmitter and receiver modems), so that each modem routes the same bits to the same of such devices. In general, it was anticipated, by means of the preferred example, that the first coded bits (in time) are routed to the device for processing frame maps 104, since it takes longer for the device to draw frame maps to process the data than to the other devices. Thus, it is preferred that the device for plotting frame maps 104 process the fractional bits associated with high-speed transmissions, these fractional data bits are represented so that the transmission of the input data is achieved in the most efficient manner. . Fractional data bits occur when data is transmitted at very high speeds, such as at a symbol rate of 3,200 hertz indicating the transmission of 3,200 symbols per second. With the modem that transmits (for example) 14,400 bits per second, the 3,200 symbols that are transmitted every second will not be evenly divided into the 14,400 bits per second that transmission allows, resulting in a transmission rate of 4 bits per symbol. The device for plotting frame maps 104 will consequently represent the fractional bits on a block of 8 symbols; the data is thus represented to transmit 36 bits on 8 symbols each time or an average of 4 bits per symbol at a time. If the transmission does not need to represent fractional bits then the device for plotting frame maps 104 will not serve a specific function and will simply pass the data bits fed directly therethrough to the mapping device 108. The speech frequency control signal obtained through the processing of the analog voice frequency signal in the encoder 101 is passed from the FIFO 102 directly to the mapping device 108. The mapping device 108 represents or traces and rotates the received digital data of which they select four predetermined bits Rl, R2, R3 and R4. These selected bits define two rotational control symbols or marks used to define the rotation of the digital data signal. The first two-bit rotational symbol, defined by the bits Rl and R2 are selected from the data that was passed through the differential encoder 106. The rotational bit represented by R3 is selected from the data that was passed directly from the FIFO 102 to the mapping device 108. The rotational bit R4 is a feedback symbol of a trellis encoder 32, as described hereinafter with respect to the precoding of the digital data signal. The representation or plotting of those bits is conventional in the art and, thus, additional express discussion of it seems not to be necessary. The bits R3 and R4 define the second rotational symbol. The selected rotational control symbols defined by the bits Rl, R2, R3 and R4 are directed from the mapping device 108 to a rotator 112 to which the vector vector of speech frequency obtained through the encoding of the speech frequency signal analogue is also introduced to the rotator 112. On the rotator 112, the vector signal of the vocal frequency is rotated according to the rotational information of the selected bits Rl, R2, R3, R4 which, as described above, define the rotation of the digital data signal received by the device for mapping 108. In this way, the vector signal of the speech frequency is rotated accordingly according to the rotation of the digital data signal. If the digital data signals were not rotated then the rotator 112 would have no effect on the vector vector of speech frequency. • The digital encoded data represented and rotated by the device for mapping 108 are fed to a precoder 20 in which an oscillating signal is added to it. Figure 5 illustrates the constellation of plotted data signals, including the digital data signals and the speech frequency control signal, at the output of the map-making device 108; the signal defining this constellation is taken at the point marked "1" in Figure 1. The digital data signals can thus be represented as a plurality of discrete points. The precoder 20 receives the digital data signals of the mapping device 108 as the input to the filter 22, for example a combination of finite impulse response filter and rounding device. The output of the filter 22 is applied to the rounding device 24 in which the filter output is rounded to an integer value having a predetermined number of bits. This provides symmetry within the transmitter modem to aid in the subsequent appropriate decoding of the signal in the receiving modem. If the signal has been rounded by the filter 22, then the rounding device 24 has no effect on the filter output. The output of the rounding device 24 is applied to both a quantizer 26 and a negative or inverted input of a subtracter 28. In the quantizer 26, the output of the rounding device 24 is quantized to produce an oscillating vector. The oscillating vector is then fed to an adder 30 in which it is added to the digital data signal that enters the precoder 20. The summed output of the adder 30 is fed to a positive input of the subtracter 28, in which the output of the device The rounding 24 is subtracted from it to produce the output x (n) of the precoder 20 taken at the point marked "2" in Figure 1, and which can be illustrated graphically as shown in Figure 6. The output of the subtracter 28 the filter 22 is also applied as an input. The precoder 20 functions to maintain the transmit power of the signal as a substantially flat spectrum, thereby producing a higher signal level at the receiver end of the communication channel. The precoder 20 adds the oscillating vector produced by the quantizer 26 to the transmitted signal to thereby control the magnitude of the signal so that it remains within the range of normal or intended energy. The quantizer 26 also acts to limit the magnitude of the oscillating vector; the reduction of its magnitude also reduces the distortion of the transmitted signal and allows the transmission of data at a higher energy level. The output of the quantizer 26 is also fed to a modular encoder 36, which acts to correct the state of the precoded signal. The output of the adder 30 is also fed to a symbol converter to bits 38. The intermediate signals of the precoder 20 in the different stages of this operation are fed through the modular encoder 36 and the symbol converter to bits 38 to the trellis encoder. 32. The trellis coder is well known and produces a trellis output signal that is fed back to the mapper 108 as a rotational symbol R4. More particularly, the trellis encoder 32 is placed in a feedback loop with the precoder 20, to decrease the expansion of the signal constellation and reduce the magnitude of the oscillating vector that is added to the data signal. The trellis encoder 32 additionally provides the redundancy bit selected as rotational bit R4 to the mapping device 108 to improve the operation, and is added to the fractional transmission data that is taken into account by the device for plotting frame maps. .

Figure 6 graphically depicts the constellation of signals x (n) at the output of the precoder 20 and marked "2" in Figure 1. The precoder 20 operatively fills the transmission constellation and adds the oscillating vector, which can be illustrated graphically as a vector used to minimize and compensate for noise in the transmission channel. This filling of the constellation and addition of the oscillating vector effects a sufficient reduction of the noise in the communication channel to provide a 1-2 dB improvement in a bad channel. The precoded data signal x (n) is applied to an adder 114, in which it is added to the vocal frequency vector signal that was rotated from the encoder 101. Figure 7 illustrates the precoded and vector frequency digital data signals combined vowel at the output of adder 114 and marked "3" in Figure 1. The voice frequency vector is shown as a vector attached to or having its origin in the precoded digital data signal to which it has been added. In conventional voice / data transmissions the energy level of the speech frequency signal is maintained so that, when graphically illustrated, the speech frequency signal vector does not extend beyond the boundaries of its originating quadrant and in this way it regulates the energy level of the vocal frequency signal. The decoding errors, therefore, are minimized at the receiver. In the addition of the speech frequency signal to the precoded data signal, the oscillating vector adds to and effectively deflects the vector vector of speech frequency; this deviation may, in some cases, extend the vector of the speech frequency signal to a different quadrant from that of the data signal to which it is attached. Unlike conventional simultaneous voice / data transmissions, in which such deviation of the vector from the speech frequency signal to a different quadrant usually results in a decoding error in the receiver, such decoding errors do not result in practice of the present invention since the vector vector of speech frequency will be deviated back to its original quadrant and magnitude after subtraction of the oscillating vector before decoding. In any case, the combined voice and data signals of the adder 114 are passed through a non-linear encoder 116 and a modulator 117 in which the signals are modulated or encoded to be transmitted to a remote receiving modem in accordance with the conventional techniques. Figure 2 illustrates a pre-emphasis circuit 111 which can be optionally implemented or incorporated into the transmitter of Figure 1 to pre-encode or pre-emphasize the vector vector of speech frequency before combining it with the pre-coded digital data signal. This circuit performs a function similar to that of the data precoder, operating to improve the frequency response of the vector signal of voice frequency after filtering and decoding in the receiver. The pre-emphasis circuit 111 of Figure 2 is connected as a feedback loop between the rotator 112 and the adder 114. In the circuit 111, the rotated vocal frequency vector signal of the rotator 112 is applied to an adder 113, the output from which is fed both the adder 114 and the filter 115, for example a finite impulse response filter and combined rounding device. The filter 115 filters the voice signal that was rotated and provides a filtered feedback signal to the adder 113 for addition to the vocal frequency vector that was rotated, thereby pre-emphasizing the vector vector signal of voice frequency that was made turn. A voice-frequency vector modulator 117 can also be interposed between the output of the filter 115 and the adder 113 placed to receive the filtered signal from the filter 115 and provide the further modulation and pre-emphasis of the vocal frequency vector that was rotated. The inclusion of the pre-emphasis circuit 111 in the transmitter of Figure 1 has the damaging effect of slightly increasing the energy in the transmitted signal. Nevertheless, this effect is greatly exceeded by the improved frequency response of the signal received at the receiver. In the remote modem or receiver (Figure 3), the transmitted signals are input from the communication channel and are initially passed through a compensator 118 and a non-linear decoder 120, in which the signals are compensated and decoded in accordance with well-known modem technology and the corresponding coding techniques employed in the transmitter modem. The signal present at the output of the non-linear decoder 120, described in Figure 7 and marked "3" in Figure 3, is the same signal that is present in the input of the non-linear encoder 116 of the transmitter modem 100. The signal decoding of the decoder 120 is then passed through a noise purification filter 122, for example a finite impulse response filter and combined filing device, which removes the oscillating vector and produces a signal consisting of a plurality of different points representing the precoded digital data and the speech frequency vector signal, as described in Figure 8 and marked as "4" in Figure 3. The noise purification filter 122 is connected to a power supply forward, so that its filtered output is added to the output of the non-linear decoder 120 in an adder 123. As shown in Figure 8, there are more disti points there. as in the graph of Figure 5, which represents the constellation of signals before precoding for transmission. This increase is due to the filling, as described above, of the signal constellation during precoding. The additional points in the constellations received in this way represent artificial points generated by the precoder and are identified by a reconstruction circuit of the precoder 130, which, through conventional reconstruction techniques, operates to identify and remove the artificial points present. in the constellation of Figure 8. The exact manner of removal of the additional points is well known and conventional in the art and modems of currently available data incorporating precoding and reconstruction of the precoder. It will also be observed in Figure 8 that the vocal frequency vector signal has deviated into a single quadrant and did not extend further into a second quadrant; This is due to the removal or subtraction of the oscillating vector. As described above, the sum of the pre-emphasis circuit 111 in the transmitter of Figure 1 acts to flatten the transmitted signal, thereby compensating the effects of the noise purification filter 122. Without such pre-emphasis, the filter 122 will emphasize or attempt to decode , and in this way will affect in a damaging way, a vectorial signal of voice frequency not emphasized or not coded. The output of the filter 122 is passed to both a Viterbi decoder 124 and a delay line of the compensator 126. The Viterbi decoder 124 detects and identifies the rotation of the speech / data signal, i.e. the rotation defined by the bits of selected data R1, R2, R3 and R4 which were used to rotate the vector signal of the vocal frequency in the transmitter, and produce a corresponding anti-rotation signal. The delay line 126 is placed in parallel interconnection to the Viterbi decoder 124 to effectively compensate for the delays associated with the processing and generation of the anti-rotation signal in the Viterbi decoder. As pointed out above, the signal is normally rotated in the transmitter modem to effectively resist interference in the communications channel; absent such rotation, such a transmitted signal is very sensitive to interference, the data bits Rl, R2, R3, R4 have no effect on the speech frequency signal when they are input to the rotator of the transmitter 112, and the Viterbi decoder 124 simply the unmodified signal passes directly to a disconnector 128. Disconnector 128 receives, as its input, both the output of the Viterbi decoder 124 and the delayed signal of the delay line of the compensator 126, which is the same signal of the adder 123 The disconnector 128 separates the data signal from the vector signal of voice frequency and feeds the separated data signal to both a reconstruction circuit of the precoder 130 and the negative or inverted input of a subtracter 132. The data signal separated by the disconnector 128 and described graphically by the plurality of discrete points in Figure 8 is then passed to the reconstruction circuit of the precoder 130. Circuit 130 - the construction and operation of which are conventional in the art - effectively reconstructs the data signal that was fed to the precoder 20 in the transmitter modem. The artificial points in the constellation of Figure 8 although not present in Figure 5 are identified by the reconstruction circuit of the precoder 130, as conventionally known and mentioned above. More particularly, the input signal to the circuit 130, after passing to an adder 156, is applied to a filter 154, for example a finite impulse response filter and a combined rounding device, whose output is fed back to the subtractor 156 for the subtraction of the output of the switch 128. The output of the filter 154 is also applied to a modular decoder 158 and then to an adder 160, in which it is combined with the output of the subtracter 156. The output of the adder 160 is fed to a disconnector 140, which removes the points of the artificial constellation identified by the reconstruction circuit of the precoder 130 and compensates the rotation signal produced by the Viterbi decoder 124 for the effects of those artificial points. The subtractor 132 receives the delayed output of the delay line of the compensator 126 at its positive or non-inverted input and subtracts therefrom the separate data signal fed to its negative or inverted input from the disconnector 128. The resulting voice frequency vector signal of the subtracter 132 is then applied to an antirotation circuit 150 together with the compensated antirotation signal of the disconnector 140, thereby effectively reversing the rotation of the vector speech frequency signal. The use of the compensated inverted rotation signal of the disconnector 140 compensates for the inverted rotation signalThe artificial bits affecting the signal have been identified by the reconstruction circuit of the precoder 130. The filtering circuit 129 of Figure 4 can optionally be interposed between the subtracter 132 and the device for reversing the rotation 150 in the arrangement of the Figure 3 to compensate for the effects of the filter and noise purification 122 on the vector signal of vocal frequency. This filtering circuit 129 could be used where the pre-emphasis circuit 11 (Figure 2) is not incorporated in the transmitter. In this way, these two circuits perform the same function at opposite ends of the communications channel and the use of one instead of another is a matter of design choice that can, for example, be standardized throughout the industry. The filtering circuit 129 includes a filter 133, for example, a finite impulse response filter combined with a rounding device, which receives and filters the vector vector of speech frequency applied to the rotator 150. The filtered output signal is then subtracted of the output of the subtracter 132 in a subtracter 131. The thus compensated signal of the subtracter 131 is fed to both the filter 133 and the rotator 150.

Returning to Figure 3, the voice frequency vector signal is rotated to the opposite in the device to reverse the rotation 150 according to the compensated inverted rotation signal of the disconnector 140, and is decoded using frequency signal decoding techniques conventional vowels in a decoder 152 to recover the analogue vocal frequency signal originally input to the transmitter modem. The data signal of the disconnector 140 is applied to a device for reversing traces or maps 142, to a device for reversing traces or frame maps 144, to a differential decoder 146, and finally to an intermediate circuit FIFO 148 from which the signal The original digital data that was input to the transmitter is produced. A modem constructed according to the present invention as described above, in this way, operates to simultaneously transmit and receive voice and data signals. In use, the modem transmitter 100 receives its input and processes an analog voice frequency signal using substantially the techniques of conventional voice frequency signal coding to produce therefrom a vector voice frequency signal and a control signal that is indicative or representative of the coding scheme used to encode the speech frequency signal. The modem also receives, as another input, digital data and processes that data using data coding techniques that are substantially conventional for high-speed modems and that incorporate digital data precoding. The voice frequency control signal and the digital data are fed to the intermediate circuit FIFO 102 and multiplexed before the representation or plot, rotation and precoding. The device for mapping maps and rotates the data for transmission and by default selects, from the received digital data signal, four rotation bits, which are used to define the rotation of the digital data signal. The selected rotation bits are fed to a rotator 112 to be used in the rotation of the vector voice frequency signal in the same manner as the rotation of the primary data signal. The bits of the non-selected or remaining digital data signal are passed through a precoder, which encodes the digital data to thereby reduce and compensate for the effects of noise to which the signal may be subjected during transmission. The rotated speech frequency signal is combined with the precoded digital data signal, and the combined signal is fed to a conventional non-linear encoder 116 and the modulator 117 for coding and modulation before transmission according to the techniques of transmission of conventional signals. Prior to combining with the data signal, the vector vector of voice frequency can also be pre-coded or pre-emphasized to flatten the signal and compensate for the filtering effects in the receiving modem. The transmitted voice / data signal is received by a remote receiver modem in which it is passed (Figure 3) through a compensator 118 and a non-linear decoder 120. The signal is then filtered in a noise purification filter 122 to remove the oscillating vector summed during the precoding of the digital data signal and to minimize and compensate for the effects of noise in the transmission channel. The filtered signal is then applied concurrently to a Viterbi decoder 124 and a delay line of the compensator 126. The delay line passes the incoming signal with a predetermined delay corresponding to the processing time or delay at which the same signal it is submitted concurrently in the Viterbi decoder 124. The Viterbi decoder 124 generates a rotation signal, based on the rotation of its inputs, which is then combined in a disconnector 128 with the output of the delay line of the compensator 126 to separate the precoded digital data signal from the combined signal. The separate digital data signal is then fed to a reconstruction circuit of the precoder 130. The reconstruction circuit 130 effectively reconstructs the precoded digital data signal by identifying the effects, ie any artificial digital data signals, of the transmitter modem precoder 20. The reconstructed signal is then passed through a disconnector 140, which removes the artificial digital data signals identified by the reconstruction circuit 130 and compensates for the inverted rotation signal produced by the Viterbi decoder. The precoded digital data signal separated by the switch 128 is also subtracted from the combined signal to obtain the vector voice frequency signal. The speech frequency vector signal is applied to the device to reverse the rotation 150 together with the compensated inverted rotation signal of the disconnector 140 to effectively reverse the rotation of the vector voice frequency signal. The speech frequency vector signal is then decoded according to the conventional techniques in the decoder 152 to recover the analogue vocal frequency signal originally input to the transmitter modem. The data signal of the switch 140 is also decoded to recover the original data signal that was input to the transmitter modem. In this way, the transmitter and receiver devices or portions of modems constructed in accordance with the invention, as described herein, operate to respectively transmit and simultaneously recover voice and data signals communicated at high speeds using precoding of the signal from digital data and may also, if preferred, incorporate pre-emphasis or pre-coding of the analog voice frequency signal. The precoding of data and voice signals minimizes the effects of noise present in the transmission or communication channels and thus allows the transmission of data at high energy levels with little distortion. Previously, simultaneous voice and data transmissions were not possible at such high speeds, high energy levels, and low levels of distortion. Of course, it was also contemplated that the transmitting and receiving portions of the modem of the invention should be incorporated into separate devices instead of into a single, dual-purpose devices operable to both transmit and receive voice and data simultaneously. Those and other similar variations, which are apparent to those skilled in the art with knowledge of this discussion, are completely within the scope of this invention. Thus, although the fundamental novel features of the invention applied to a preferred embodiment thereof have been shown, described and pointed out here, the different omissions, substitutions and changes in the form and details of the illustrated devices must be understood, and in its operation, can be made by those skilled in the art without departing from the spirit of the invention. For example, it was expressly intended that all combinations of those elements and / or steps of the method that perform substantially the same function in substantially the same way that achieve the same results are within the scope of the invention. Furthermore, it should be recognized that the structures and / or elements and / or method step shown and / or described in connection with any form or described modality of the invention can be incorporated in any other modality described, disclosed or suggested as a general matter of choice. of design. Therefore, the intention is to be limited only by what is indicated in the scope of the appended claims. It is noted that in relation to this date, the best method known by the applicant to carry out the aforementioned invention, is the conventional one for the manufacture of the objects referred to therein. Having described the invention as above, property is claimed as contained in the following:

Claims (13)

1. A modem (modulator-demodulator) for simultaneously transmitting pre-coded voice and data signals on a single communication channel to a remote destination and for retrieving simultaneous voice and pre-coded data signals transmitted on a single communications channel from the communication channel uni remote source, the modem is characterized in that it comprises: a transmitter that includes: data processing means for plotting or representing a map of a user data signal that varies with the time fed to the transmitter to produce a defined data signal represented by a plurality of data bits; voice frequency signal processing means for encoding a speech frequency signal that varies with time fed to the transmitter; means for precoding the represented data signal; means for combining the precoded data signal with the encoded frequency signal; and means for simultaneously transmitting the coded voice frequency and combined precoded data signals over the communication channel to a remote destination; and a receiver comprising: means for receiving from the communication channel, as an input to the receiver, coded voice frequency signals and precoded data transmitted simultaneously from a remote source; means for filtering the combined signals received; separation means connected to the filtering means for separating the encoded voice frequency signal and the precoded data signal from the filtered combined signal; means for decoding the separated encoded speech frequency signal to recover therefrom an analog voice frequency signal originating from the remote source; means for reconstructing the precoded data signal to define a reconstructed data signal and means for decoding the reconstructed data signal to recover therefrom a data signal originating from the remote source.

2. The modem according to claim 1, characterized in that the data processing means comprise means for selecting, from the plurality of data bits, predetermined bits representing a rotation of the data signal represented; the combining means comprises means for receiving the predetermined bits to rotate the coded voice frequency signal in accordance with the rotation represented before the combination of the coded voice and precoded data signals; and the receiver further comprises means for determining the rotation and inversion of the rotation of the separated coded speech frequency signal and the reconstructed data signal.

3. The modem according to claim 2, characterized in that the means for precoding comprise a feedback coder coupled to and to feed a feedback bit to the data processing means, the feedback bit comprises one of the predetermined bits.

4. The modem according to claim 1, characterized in that the transmitter further comprises a non-linear encoder for coding and a modulator for modulating the coded voice frequency and combined pre-coded data signals before the transmission of the combined signals on the communication channel .

5. The modem according to claim 2, characterized in that each of the predetermined bits comprises the data input or fed to the transmitter.

6. The modem according to claim 2, characterized in that the combining means further comprises means for pre-emphasizing the coded voice frequency signal.

7. The modem according to claim 2, characterized in that the receiver further comprises means for de-emphasizing the separated coded speech frequency signal before reversing the rotation.

8. A transmitter for use in a modem for simultaneously transmitting coded voice frequency signals and precoded digital data on a single communication channel, the transmitter is characterized in that it comprises: means for processing data for plotting or representing a map of a data signal of user that varies with the time fed to the transmitter to produce a data signal represented and rotated defined by a plurality of bits; means for selecting, from the plurality of data bits, predetermined bits representing the rotation of the data signal represented or plotted; means for processing signals for receiving and encoding a speech frequency signal that varies with time fed to the transmitter to generate a coded voice frequency signal; means for precoding the represented data signal; rotator means for receiving both the predetermined bits and the coded voice frequency signal and rotating the coded voice frequency signal according to the rotation represented by the predetermined bits; means for combining the precoded data signal and the coded voice frequency signal that was rotated to produce a combined voice / data signal; and means for transmitting the combined voice / data signal through a single communication channel.

9. The transmitter according to claim 8, characterized in that the means for precoding comprise a feedback coder coupled to and for feeding a feedback bit to the selection means, the feedback bit comprises one of the predetermined bits.

10. The transmitter according to claim 8, characterized in that the transmitter comprises a non-linear encoder for coding and a modulator for modulating the combined voice / data signal before the transmission of the combined voice / data signal on the communication channel.

11. The transmitter according to claim 8, characterized in that the combining means further comprise means for pre-emphasizing the coded voice frequency signal.

12. A receiver for use in a modem for recovering analog voice frequency signals and user data of a combined voice / data signal transmitted on a single communication channel by means of a remote source, the remote source encoding the speech frequency signal analog and precodes the user data signal before transmission, the receiver is characterized in that it comprises: means for receiving the combined signals from the communications channel as input to the receiver; means for filtering the received combined signal; separation means coupled to the filtering means for separating the encoded voice frequency signal and the precoded data signal from the filtered combined signal; means for reversing the rotation and decoding the separated coded speech frequency signal to recover the analog voice frequency signal originating from the remote source; and means for reconstructing the precoded data signal to retrieve the user data signal originating from the remote source.

13. The receiver according to claim 12, characterized in that it further comprises means for de-emphasizing the separated coded speech frequency signal before reversing the rotation. SUMMARY OF THE INVENTION The present invention relates to a high-speed modem for simultaneously transmitting voice frequency signals and pre-coded digital data signals on a single communication channel. The modem is operable to combine a voice frequency signal with a pre-coded digital data signal for transmission at high speeds, high energy levels and low distortion previously achievable by high speed data only modems. The speech frequency signal is processed using conventional data processing techniques to produce a speech frequency signal and a control signal containing information related to the encoding of the speech frequency signal. The control signal is multiplexed and displayed for transmission with the digital data. The selected bits of the multiplexed data are used to define the rotation of the digital data and to rotate or rotate the speech frequency vector. The digital data is precoded to compensate and minimize the noise in the communication channel. The vocal frequency vector that was rotated and the precoded digital data are then combined and transmitted. At a remote location, the transmitted signal is received by the receiving modem and is filtered and separated to thereby recover the individual encoded signals. The separation of the coded frequency signal from the precoded digital data signal is effected before the reconstruction of the precoded digital data signal. Then the rotation of the coded voice frequency signal is reversed. The encoded speech frequency and precoded digital data signals are then individually decoded to recover the data voice frequency signals that originated in the transmitter modem.