JPH01108824A - Communication equipment - Google Patents

Abstract

PURPOSE:To add other functions by incorporating a backward channel speech function to a signal processor of a MODEM device to attain the small-sized equipment, common use of components and cost reduction. CONSTITUTION:A conventional backward channel exclusive use IC is removed and similar function is incorporated in the inside of the digital signal processor(DSP). Moreover, a detector 310 is a narrow band filter passing only a band component of a backward channel from a received data from an A/D converter 302. Then the extracted backward channel signal as a result of filtering by the detector 310 is transferred to a reception terminal 309 as the backward channel information demodulated by the demodulator 312. Then various control for the equipment is applied by a controller 320. Then the MODEM device with backward channel communication function is realized with simple constitution and the MODEM is further miniaturized size, used in common, and the cost is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION <Field of Industrial Application> The present invention relates to a communication device, and particularly to a communication device having a modem function.

<Conventional technology> Digital signal data to the general public! When transmitting via an I1I (analog line), a modulation/demodulation device (modem) is required to convert the digital signal into a desired analog signal and vice versa. FIG. 2 shows an outline of a conventional communication device having this modem function. In the figure, the part surrounded by dotted lines is the part included in the modem.

This figure shows the configuration of the receiving side. Is the transmitted signal a component outside the transmission band?
The signal is removed by the AGC 111, controlled to a signal level handled by the receiving side, converted into a digital signal by the A/D converter 112, and demodulated into the original signal (signal before modulation) by the demodulator 113. Further, the timing extraction circuit 114 performs nonlinear processing on the demodulated data from the timing extraction circuit 113 to extract timing information, and applies feedback to the A/D converter to extract appropriate sampling points. on the other hand,
The output signal of the equalizer 115 is determined to be a code point by the determiner 116, decoded by the decoder 117, and randomized by the scrambler 101. The generated signal is returned to the receiving terminal 119 and received.

Block 210 is a backward channel IC that constantly monitors the hackword channel, and is used for FSX, P
It also has demodulation of SK, etc., and transfers received information to the receiving terminal 209 upon arrival of the signal. Therefore, for example, when a transmission error occurs on the main channel, the hackword channel is used as a means for retransmitting the error.

Note that the hackword channel represents the use of a part of the telephone line band as a channel for transmitting data other than image data.

<Problems to be Solved by the Invention> However, in the above conventional example, as a means for detecting and demodulating backward channel signals, as shown in FIG.
Because it uses a dedicated IC for backward channels,
This not only hinders the miniaturization, standardization, and low cost of modem devices, but also poses a huge obstacle to adding and changing functions.

The present invention aims to solve the above-mentioned problems.

<Means for Solving the Problems> In order to solve the above-mentioned problems, the present invention is characterized in that a backward channel call function is incorporated into the signal processing processor of a communication modem device.

<Operation> The signal processing processor performs a hackword channel call function.

<Example> Hereinafter, an example of the present invention will be described using the drawings. FIG. 1 is a block diagram showing the circuit configuration of an embodiment of the present invention;
4 is a diagram showing the transmission spectrum, FIG. 4 is a diagram showing the configuration of a detector for detecting a hackword channel signal, and FIG. 5 is a flowchart explaining the operation of the controller 320 shown in FIG. 1.

The configuration shown in FIG. 1 removes the backward channel dedicated IC 210 in FIG. 2 and incorporates a similar function inside the DSP. The functions of 300 to 309 in FIG. 2 are the same as those of 110 to 119 in FIG. The detector 310 is a narrow band filter that passes only the backward channel band components from the received data from the A/D converter 302. The backward channel signal extracted as a result of filtering by the detector 310 is demodulated by the demodulator 312 and transferred to the receiving terminal 309 as backward channel information.

320 is a controller that controls each part of the apparatus shown in FIG.

Next, Figure 3 shows the CCITT recommendation V29QAM method 960.
This is the transmission spectrum when the roll rate of the 0 bit/sec modem is 10%. The nominal pass band of the general public line is 300 H2 to 3400 H2, and is used as a covering word channel between the normal high frequency bands 3020 H2 to 3400 H217) shown as B in the transmission spectrum diagram of FIG. Note that the frequency band indicated as A is a band for transmitting image data.

Next, using FIG. 4, the detectors 310501, 502, 5 for detecting the backward channel signal shown in FIG.
07 are adders, respectively. 505, 506 are delay devices having a delay of sampling period T; 503, 504, 5;
08 are multipliers each having a coefficient multiplied by a I + 2 + -1. Therefore, the transfer function of the circuit shown in the figure is expressed by the following equation.

On the other hand, when using the same transfer function, the parameter a l +
32 has a relationship expressed by the following two equations.

Here, ω. is the central angular frequency, T is the sampler period,
Q means selectivity.

Therefore, by setting ω0 and Q to desired values suitable for the backward channel B shown in FIG. 3, the parameters a8 and a2 are determined from the equations (1) and (2).

Next, an algorithm for the operation of the controller 320 of this embodiment will be explained with reference to the flowchart of FIG. First, the received data A/D converted at 600 is sent to the DSP.
Then, in 601, the loop counter fLc is set to 1, and in 602, the loop counter Jlc
A determination is made. If nc=0, the process proceeds to step 612 where a backward channel signal is detected, demodulated in step 613, and then output to the receiving terminal 309 in step 609.

On the other hand, if uc=1, the received signal is demodulated in step 603, and then timing extraction is performed in step 604.
Step 605 Equalization, Step 606 Judgment, Step 6
Line distortion is removed by equalization processing for performing a series of demodulations including decoding at step 07 and discranger at step 608, and the signal is output as a receiving terminal at step 609. Step 6
At step 10, a determination is made on the loop counter, and if fLc=o, the process returns to step 600, and if 1c=1, it is decremented at 611, and then the process proceeds to 602, where the series of operations described above are repeated.

Further, FIG. 6 is a block diagram showing the configuration of the transmitter in the apparatus of this embodiment.

In FIG. 6, 600 is a transmitting terminal, and 601 is a scrambler that scrambles data output from the transmitting terminal.
1602 is an encoder that converts data scrambled by a scrambler into a code; 603 is an encoder 602
A filter 604 pulse-shapes the output of
605 is a D/A converter that D/A converts the signal modulated by the modulator 604. 606 is a low-pass filter that removes high frequencies from the output of the D/A converter 605. , 607 is a modulator that modulates the backward channel signal. Further, the signal from the transmitting terminal 600 is distributed and supplied to a scrambler 601 or a hackword channel signal modulator in advance.

As described above, in this embodiment, when it is detected that an error has occurred during the receiving operation, the signal modulated by the transmitting side modulator 607 shown in FIG. and received by the circuit shown in FIG. This will be resent.

Therefore, through the series of processes explained so far, if a reception error occurs during reception on the main channel, an error signal is sent to the transmitting side using the hackword channel, and the transmitting side sends out the transmitted data by retransmitting it, etc. will be carried out.

In the above embodiment, a fourth method is used for hackword channel signal detection.
It is possible to use one stage of the narrowband filter shown in the figure, or of course to use multiple stages of this filter in order to improve the detection characteristics.

Digital signal processing processor (DSP) in this embodiment
The modem device incorporating the backward channel detection circuit is as described above, and can provide the following effects.

By removing the IC from the conventional modem device with a dedicated backward channel IC and incorporating a backward channel signal detector and demodulator into the DSP, a modem device with a hackward channel communication function can be created with a very simple configuration. This has led to further miniaturization of modems.
Standardization and lower prices can be achieved.

In addition, in this embodiment, the demodulator 113 and the equalizer 115
, determiner 116, decoder 117, discrantzler-1
01 as separate hearts, it goes without saying that these functions may be configured as software using the aforementioned DS and P.

<Effects of the Invention> As explained above, according to the present invention, the backward channel call function is incorporated into the signal processing processor of the modem device, so the device can be made smaller, and parts can be made more common.
Not only does it reduce costs, but it also allows you to add other functions.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of an embodiment of the present invention, FIG. 2 is a block diagram showing the configuration of a conventional device, FIG. 3 is a diagram showing the transmission spectrum of the device in FIG. 1, and FIG. 4 is a diagram showing the configuration of the detector 310 shown in FIG. 1, FIG. 5 is a flowchart explaining the operation of the controller 320 shown in FIG. 1, and FIG. 6 is a block diagram showing the configuration of the transmitting section in this embodiment. It is a diagram. 310...Detector 312...Demodulator 320...Controller

Claims (4)

[Claims] (1) A communication device characterized in that a backward channel call function is incorporated into a signal processing processor of a communication modem device. (2) The communication device according to claim 1, wherein the signal processing processor includes means for demodulating the modulated signal. (3) The communication device according to claim 1, wherein the signal processing processor includes means for equalizing the demodulated signal. (4) The communication device according to claim 1, wherein the signal processing processor includes means for determining the type of the equalized signal.