JPH0369457B2 - - Google Patents

Description

[Detailed description of the invention]

[Summary] Regarding the SAT signal detection device, a reference frequency based on code information is used as the master clock of the digital phase synchronization circuit for SAT signal extraction, and it is determined whether the SAT signal is received normally or not. . [Industrial Application Field] The present invention is a supervisory audio tone (SAT) equipped in a mobile communication system mobile device.
The present invention relates to a signal detection device. The SAT signal detection device of the present invention is used, for example, in car phones, mobile phones, and the like. For example, in mobile communication systems such as cellular car telephones, the state of the communication line between the base station and the mobile device is outside the voice band of the communication channel (for example, 6 kHz).
The network is constantly monitored using the SAT signal superimposed on the mobile station, and if the line quality deteriorates due to the mobile device moving to another cell, the line is handed over to the base station in the destination cell. To avoid interference with the same frequency between each cell, multiple SAT signals, for example, three types (5970Hz,
6000Hz, 6030Hz) frequencies are used, and the mobile device extracts the SAT signal from the received waves, identifies and reproduces it, determines whether the receiving channel is good or bad, and sends it back to the base station. The base station monitors the quality of the communication line by measuring the frequency, distortion rate, jitter, etc. of the returned SAT signal. [Prior Art] FIG. 3 shows a conventional SAT signal detection device in a mobile device for receiving and identifying SAT signals. In this conventional type, the SAT signal is 5970
Three waves are used: Hz, 6000Hz, and 6030Hz. In FIG. 3, 1 is a receiving circuit, 2 is a data detection circuit, and 3 is a control circuit including a microprocessor. 4' is a SAT signal detection circuit, 41
is a band filter that passes the SAT signal band (6kHz band). 48 is an analog phase locked circuit PLL, which includes a phase comparator 481, a low-pass filter 482,
Voltage controlled oscillation suppressor 483 and N frequency divider 484
It consists of: 42 is a digital phase locked circuit DPLL, which includes a phase comparator 421, a sequential filter 422, a frequency division number selector 423, and an M frequency divider 42.
4, and (L-1), L, (L+1) frequency divider 42
It consists of 5. This digital phase synchronization circuit 42 receives the oscillation output (955.2kHz,
960.0kHz, 964.8kHz) as the master clock from the received wave after passing through the band filter 41.
Extract the SAT signal. 43 is a counter that measures the frequency of the oscillation output of the digital phase synchronization circuit 42 and outputs it in the form of a color code to be described later; 49 is a color code discriminator. The color code is a code sent from the base station when connecting a line, and is sent by the base station.
It represents the frequency of the SAT signal, and has a correspondence relationship as shown in Table 1 below.

[Problem that the invention seeks to solve]

Conventional devices use the oscillation output of an analog phase-locked circuit as the master clock of a digital phase-locked circuit for extracting the SAT signal. For this reason,
This analog phase synchronization circuit is the cause that prevents SAT signal detection equipment from becoming fully digital, and is a problem in moving the equipment to LSI. [Means for solving the problems] In order to solve the above problems, the present invention
The SAT signal detection device, as shown in Figure 1,
A digital phase synchronization circuit 11 for extracting a SAT signal from received waves, a reference frequency wave generation circuit 12 for generating a plurality of reference frequency waves corresponding to a plurality of frequencies assigned in advance as SAT signals, and a control circuit when connecting a line. a selection circuit 1 which selects the frequency of the SAT signal to be received from the reference frequency wave generation circuit based on code information sent from the base station via the channel and supplies it to the digital phase synchronization circuit as a master clock;
3. Compare the frequency of the SAT signal extracted by the digital phase synchronization circuit with the frequency to be received based on the code information sent from the base station, and determine whether the frequency matches or does not match.
A determination circuit 14 is provided to determine whether or not reception of the SAT signal is normal. [Operation] When the base station and the mobile device are connected, one reference frequency wave of the reference frequency generation circuit 12 is selected based on information sent from the base station via the control channel and sent to the digital phase synchronization circuit 11. Supplied as master clock. As a result, the digital phase synchronization circuit 11 detects SAT from the received wave.
The signal can be extracted and reproduced, and furthermore, the determination circuit 14 reliably determines whether or not the reception of the SAT signal is normal. [Embodiment] A SAT signal detection device as an embodiment of the present invention will be described below with reference to FIG. FIG. 2 is a block diagram of the SAT signal detection device in a mobile device of a mobile communication system. In this device shown in Figure 2, the SAT signal is 5970Hz, 6000Hz, 6030Hz.
Three waves of Hz are used. In FIG. 2, radio waves are guided to a receiving circuit 1 via an antenna. The reception output of the reception circuit 1 is divided into two parts, one to the data detection circuit 2 and the other to the SAT.
The signal is guided to the signal detection circuit 4. The output of the data detection circuit 2 is guided to a control circuit 3 including a microprocessor for processing. In the SAT signal detection circuit 4, the receiving circuit 1
The received output from the SAT signal band (6kHz band) is guided to a digital phase synchronization circuit 42 through a band filter 41 that passes the SAT signal band (6kHz band). The digital phase synchronization circuit 42 includes a phase comparator 421, a sequential
It is configured to include a filter 422, a frequency division number selector 423, an M frequency divider 424, and a (L-1), L, (L+1) frequency divider 425, and the SAT signal frequency is determined from the output of the M frequency divider 424. The oscillation output is obtained. The oscillation output wave of the M frequency divider 424 is further guided to the counter 43 and also to the phase shifter 5. The counter 43 measures the frequency of the oscillation output from the M frequency divider 424 and outputs the color code corresponding to the above-mentioned Table 1 to the matching circuit 44. A color code is also led to the collation circuit 44 from a color code discriminator 49. A color code discriminator is a code obtained based on information sent from a base station when a line is connected, and the color code represents the frequency of the SAT signal sent by the base station using the correspondence shown in Table 1. There is. The reference oscillators 47 ₁ , 47 ₂ , 47 ₃ are each
This is an oscillator that generates reference frequency waves of 955.2kHz, 960.0kHz, and 964.8kHz, and each oscillation output is guided to the reference oscillator selector 45. Based on the color code from the color code identifier 49, the reference oscillator selector 45 selects a reference oscillator having a reference frequency corresponding to the color code, and supplies its oscillation output to the digital phase synchronization circuit 42 as a master clock. Here, as mentioned above, the three reference frequencies 955.2kHz, 960.0kHz, and 964.8kHz are the frequencies of the three received SAT signals (5970Hz, 600kHz).
Hz, and 6030Hz), and the frequency of the SAT signal actually received at that time (5970Hz, 6000Hz, and 6030Hz) is determined based on the code information sent from the base station. )
(955.2kHz, 60.0kHz, and
By selecting either 964.8kHz as the master clock and performing phase synchronization, the band for each synchronization can be made smaller, improving noise resistance and shortening the synchronization time. I can do it. Note that the transfer device 5, data generator 6, and transmission circuit 7
is the same as that in Figure 3. The operation of the embodiment apparatus of FIG. 2 will now be described. When establishing a line connection between a base station and a mobile device, various types of control information are sent to the transport device via the control channel.
Contains information about the frequency of the SAT signal. The control circuit 3 of the mobile device sends a signal to the color code discriminator 49 based on this information so that the color code discriminator 49 outputs a color code corresponding to the SAT signal frequency. Thereby, the reference oscillator selector 45 selects a reference oscillator with an oscillation frequency corresponding to the SAT signal frequency, and supplies the reference frequency output to the digital phase synchronization circuit 42 as a master clock. As a result, if the digital phase synchronization circuit 42 normally performs phase synchronization and sends out a synchronized output, it means that the SAT signal frequency transmitted in advance by the base station matches the actually received SAT signal frequency. Therefore, it can be determined that communication is being performed without any problem through a normal communication channel. The above judgment is further confirmed by the counter 43, the collation circuit 44, and the color code discriminator 49. The output from the digital phase synchronization circuit 42, that is, the SAT signal, is further transmitted to a transporter 5, a transmitting circuit 7,
and is sent back to the base station via the antenna. [Effects of the Invention] According to the present invention, the analog phase synchronization circuit for generating the master clock of the digital phase synchronization circuit, which was necessary in the conventional type, is no longer necessary.
This makes it possible to completely digitalize the SAT signal detection device, which will be advantageous in moving the device to LSI.

[Brief explanation of drawings]

Fig. 1 is a block diagram of the principle of the present invention, Fig. 2 is a block diagram of a SAT signal detection device as an embodiment of the present invention, and Fig. 3 is a block diagram of a conventional SAT signal detection device. Circuit, 2... Data detection circuit, 3...
...Control circuit, 4, 4'...SAT signal detection circuit, 5
... Phase shifter, 6 ... Data generator, 7 ... Transmission circuit, 11, 42 ... Digital phase synchronization circuit, 1
2... Reference frequency wave generation circuit, 13... Selection circuit, 14... Judgment circuit, 41... Band filter,
42...Digital phase synchronization circuit, 43...Counter, 44...Verification circuit, 45...Reference oscillator selector, 47 ₁ to 47 ₃ ...Reference oscillator, 48...Analog phase synchronization circuit, 49...Color code Identifier.

Claims (1)

[Claims] 1. In a supervisory audio tone signal detection device of a mobile device that receives and identifies a supervisory audio tone signal used in a mobile communication system, the supervisory audio tone signal is detected from received waves. A digital phase synchronization circuit 11 for extracting signals, a reference frequency wave generation circuit 12 that generates a plurality of reference frequency waves each corresponding to a plurality of frequencies assigned in advance as a supervisory audio tone signal, and a line connection. At the same time, the frequency of the supervisory audio tone signal to be received is selected from the reference frequency wave generation circuit based on code information sent from the base station via the control channel, and the master signal is transmitted to the digital phase synchronization circuit. a selection circuit 13 supplied as a clock, and the frequency of the supervisory audio tone signal extracted by the digital phase synchronization circuit;
The frequency to be received obtained based on the code information sent from the base station is compared, and depending on the match or mismatch, the supervisory audio
A supervisory audio tone signal detection device comprising: a determination circuit 14 for determining whether reception of a tone signal is normal or not.