KR0154694B1 - Radio telephone - Google Patents

Abstract

Mobile radiotelephones, such as car phones and portable radiotelephones, analyze the monitoring audio tone signal to control the call path. To this end, after detecting the end of the average period of the surveillance audio tone signal, the number of sampling clocks counted up to this point is added and stored to the sampling coefficient value of the predetermined period number in the previous state, and then the sampling period value of the current period is cleared. After calculating the average value of the addition sampling coefficient value, the average value is analyzed using the average value, and the result is a normal or error counter. After that, if the normal counter value is reached, the channel is disconnected.

Description

Monitoring audio tone signal analysis method of mobile wireless telephone

1 is a configuration diagram of a mobile wireless telephone.

2 is a flow chart of a conventional surveillance audio tone signal analysis.

3 is a flow chart of the monitoring audio tone signal analysis of the present invention.

* Explanation of symbols for main parts of the drawings

11: RF unit 12: band pass filter

13: level shifter 14: edge detector

15: CPU 16: ROM

17: RAM 18: Counter

19: low pass filter 20: mute circuit

21: amplifier 22:

speaker

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of connection and maintenance of a call in a mobile radio telephone, and more particularly, to a method for analyzing a surveillance audio tone signal.

In general, mobile wireless telephones such as mobile telephones or hand held telephones use a supervisory audio tone (hereinafter referred to as a SAT) signal to indicate whether a call is connected or not. Therefore, when the mobile phone receives the SAT signal, the mobile telephone is regarded as having a communication path and maintains a connection state. In more detail, the RF signal received through the antenna is demodulated through the RF unit 11, and in the band pass filter 12, the SAT signal band is output from the output of the RF unit 11. In the aftermath. Then, a level shifter 13 converts a sine wave signal of the SAT signal band into a square wave signal, and an edge detector 14 polls the SAT signal of the square wave. A falling edge is detected and an interrupt signal is generated to the CPU 15 at this point. Then, the CPU 15 reads the count value of the counter 18 at the time of the interrupt signal generation, resets the counter 18, and then analyzes the count value to analyze the presence or absence of the SAT signal. At this time, it is determined that the SAT signal is present in the CPU 15, and outputs the audio signal of the low pass filter 19 generated by the low pass filter in the audio signal band from the output of the RF unit 11 to the speaker 22 If it is determined that the SAT signal is not received, the mute circuit 20 is operated to mute the output of the low pass filter 19.

FIG. 2 is a conventional method of analyzing the SAT signal having the configuration as shown in FIG. 1, and the CPU 15 checks whether an interrupt signal is generated through the edge detector 14 in step 201. That is, the edge detector 14 generates an interrupt signal every time the falling edge of the SAT signal is detected, which indicates the end of the SAT signal period. Therefore, when the interrupt signal is generated, the CPU 15 reads the count value of the counter 18 in step 202, and then resets the counter 18 in step 203 to reset the count value up to now. Clear it. Then, the counter 18 is initialized at the time of the reset signal generation and resumes the counting operation at the sampling clock period. As a result, the counter 18 generates a count value for one cycle of the SAT signal. At this time, when the CPU 15 reads the count value from the counter 18, a series of operations for analyzing the SAT signal is performed. First, in step 204, the count value is within a preset minimum and maximum value range. Check if it exists. That is, the period of the SAT signal is a constant multiple of the sampling signal, and the minimum and maximum values are set by setting an allowable error range. Therefore, if the count value of the SAT signal period is present in the tolerance range, it is determined that the normal SAT signal is received and the audio signal is reproduced to the speaker 22 through the amplifier 21 in step 205. However, if the count value is smaller than the minimum value or larger than the maximum value in step (204), it is outside the tolerance range. In step 206, the CPU 15 operates the mute circuit 20 to operate the low pass filter ( Mutes the output of 19). Therefore, if the SAT signal is wrong or the state in which the SAT signal analysis is impossible due to the relative signal attenuation continues, the audio signal is muted and the state of the call is controlled.

However, in the conventional method as described above, it is difficult to discriminate according to the state of the continuous SAT signal, and the state of the call is controlled by the instantaneous operation according to the SAT signal cycle, and thus, instantaneously such as a burst error. When the SAT signal is badly received, the call path is cut off or the initial call is failed. Therefore, the failure factor for the call attempt is increased. When analyzing the SAT signal, the allowance for the analysis of three SAT tones is increased. As a result, there was a problem that may cause a malfunction according to the overlapping tolerance when connecting to the initial call.

Accordingly, an object of the present invention is to provide a method for maintaining a stable call state by analyzing an average value of a predetermined number of cycles of a SAT signal in a mobile wireless telephone and stably determining a state of a continuous SAT signal.

It is still another object of the present invention to analyze the average value generated during a predetermined number of SAT signal periods when analyzing a SAT signal in a mobile wireless telephone and determine the state of the SAT signal continuously and repeatedly, thereby connecting to a call in a weak SAT signal reception state. To provide a way to maintain the state.

Hereinafter, the present invention will be described in detail with reference to the drawings.

The system configuration for carrying out the present invention is the same as in FIG. 1, and the reference numerals are the same as in FIG.

3 is a flowchart of the present invention,

Detecting the received SAT signal and checking whether the detected signal period ends;

Initializing a current sampling count value to store a sampling count value for the SAT signal period when the period end signal of the SAT signal is generated, and then counting the next SAT signal period; and the sampling count value is within an allowable error range. The process of increasing the normal or error counter according to the analysis result, and calculating the value of the normal counter after performing the above process, maintains the connection state with a temporary call over the specified value, and simultaneously decreases the normal counter and initializes the error counter. After the execution of the process and the end of the process, and the normal counter to calculate the error counter value when the value is less than the prescribed value disconnects the instantaneous communication line over the specified value, and at the same time the error counter decreases and initializes the counter and ends the process.

Based on the above-described configuration, the present invention will be described in detail with reference to FIGS. 1 and 3.

The RF signal received through the antenna is filtered through the band pass filter 12 into the SAT signal band, and is converted into a digital signal of a square wave through the level shifter 13 and applied to the edge detector 14. At this time, the edge detector 14 checks the SAT signal of the square wave and detects the falling edge, and reads it as a period end signal of the corresponding SAT signal to generate an interrupt signal to the CPU 15. At this time, the counter 18 counts the period of the SAT signal using the sampling signal as the clock. Therefore, the CPU 15 analyzes the output of the edge detector 14 at step 202 to check whether or not a predetermined signal period is calculated for calculating the average value of the signal when the end signal of the period is generated. In step 206, the output of the sampling count value of the counter 18 is read and stored in the RAM 17. In step 206, the counter 18 is reset to initialize the next SAT predetermined signal period. However, if it is not the end of the SAT predetermined signal period in step 202, the operation continues at step 202 to check the occurrence time of the end of the SAT predetermined signal. At this time, the counter 18 continuously counts the sampling clock. I'm doing it.

After performing step 206, the CPU 15 determines whether the counter 18 is in an overflow state (ie, when the frequency is lower than the SAT signal) in step 208, and a signal lower than the prescribed frequency If so, the process proceeds to step 216 to increase the error counter by one. However, if the counter value of the prescribed frequency is detected in step 208, the average value is calculated in step 210, and after calculating the average value, in step 212, it is checked whether the average value exists between the minimum error value and the maximum error value. . At this time, if the average value is within the error setting range, it is determined to be normal, and in step 214, the normal counter is increased by one. If the average value is outside the error setting range, the error counter is increased by one. In this case, the normal counter and the error counter are SAT signal state counters for repetitively determining whether the SAT signal is normal in a predetermined number of SAT signal periods, and each SAT signal period has a predetermined SAT signal period and a current SAT signal period. After calculating the average count value by calculating the sampling count value of, the average value is increased when the average value is within the minimum error value and the maximum error value, and increases the error counter when it exists outside the tolerance range. At this time, the average value can be obtained as in the following Equation (1).

After performing steps 214 or 216 to count a normal or error counter, in step 218, the value of the normal counter is analyzed to check the status of the continuous SAT signal. That is, if the value of the normal counter is a predetermined value, the continuously received SAT signal is determined to be normal, and in step 220, the mute circuit 20 is controlled to output the low pass filter 19 to the audio signal through the amplifier 21. The speaker 22 is connected, and in step 222, the normal counter value is decreased by one and the error counter is cleared to prepare for the next state. However, if the normal counter is less than the prescribed value in step (218), it is checked whether the error counter is greater than or equal to the prescribed value in step 224. If the error counter is greater than or equal to the prescribed value, the mute circuit 20 is controlled in step (226). The output of the low pass filter 19 is muted, and at step 228 the normal counter is cleared and the error counter is decremented. However, if the normal or error counter is below the specified value, the current state is terminated.

Here, the average value is calculated using four SAT signal periods, the sampling count value of 1SAT signal period is 200, the minimum error value is 190, the maximum error value is 210, and the normal or error counter is 4, and the process is performed. Look specifically.

First, the CPU 15 reads the value of the counter 18 every time four SAT signal periods are detected and stores the values in the RAM 17. In step 210, the average value is calculated by the above equation (1) to check whether the average value is within the tolerance range. That is, when the average value is calculated by the above formula (1), the average sampling count value for the sampling count of the 4SAT period is calculated. If the average value is present between 190 and 210, the normal counter is increased by one. If the average is less than 190 or greater than 210, the error counter is increased by one. After checking the value of the normal counter, if it is over the specified value (normal counter = 4), the connection status is maintained by the call, and the normal counter is decreased by 1 for the next SAT signal period, and the error counter is initialized (normal counter = 3, Error counter = 0). Therefore, in this case, once the channel is formed, the channel is connected regardless of the state of the SAT signal until the value of the error counter becomes 4.

If the normal counter is less than or equal to the prescribed value, the value of the error counter is checked. If the error counter is greater than or equal to the prescribed value (error counter = 4), the communication line is disconnected. Counter = 3, normal counter = 0). Therefore, when the channel is disconnected, the channel remains disconnected until the value of the normal counter reaches 4 regardless of the state of the SAT signal. If the normal counter and the error counter are less than or equal to the prescribed value, the operation terminates while maintaining the current call state.

As described above, when controlling the call path state in the mobile wireless telephone, the call path is controlled by taking an average value of a count value of a predetermined number of SAT signal cycles and applying the result of the reading to the next predetermined number of signal cycle states. As a result, it is possible to control the connection to the call in a stable state by sufficient SAT signal detection, and by determining the state of the SAT signal on the basis of continuous and repetitive calculation results based on the result of sufficient signal analysis, the weak SAT Even in the reception state of the signal, it is possible to accurately perform the connection and maintenance operation to the call, which has the advantage that the call attempt can be stably performed during the initial call.

Claims (1)

A method for controlling a call path of a mobile wireless telephone, the method comprising: detecting a received surveillance audio tone signal and generating a cycle end signal; and in the process, present surveillance audio tone signal cycle when one cycle end signal of the surveillance audio signal tone signal is generated. Adding and storing the sampling count value for the predetermined number of monitoring audio tone signal periods in the previous state and initializing the current sampling count value, calculating an average value of the added and stored sampling count values, Analyzes the tolerance range and increases the normal counter or error counter according to the analysis result, and connects the communication line when the normal counter value exceeds the prescribed value after performing the above process, and initializes and terminates the normal counter decrement and error counter. The error counter value A method for analyzing the surveillance audio tone signal of a mobile wireless telephone, characterized by disconnecting a normal day-to-day communication channel and initializing and terminating an error counter and a normal counter.