KR0138175B1 - Receiving frequency compensating method in mobile telephone - Google Patents

Abstract

[Technical field to which the invention described in the claims belong]

walkie talkie

[Technical Challenges to Invent]

Fine adjustment of frequency deviation in portable radiotelephones.

[Summary of the solution of the invention]

A device for compensating for frequency deviation in a portable radiotelephone comprises means for generating a first intermediate frequency by synthesizing a received radio signal and a first reference frequency, and synthesizing the first intermediate frequency and a second reference frequency for a second intermediate frequency. Means for generating a frequency, means for detecting reception sensitivity at the second intermediate frequency, channel selection data for generating the first reference frequency, and first division for generating the second reference frequency Data and second division data, wherein the first sensitivity data is increased when the reference sensitivity strength is large and the first division data is decreased when the reference sensitivity strength is small by comparing the reception sensitivity strength and the reference reference sensitivity strength. And means for generating the first reference frequency by loading the channel selection data, and phase synchronizing loop means. And means for loading the first divided data and the second divided data, respectively, and generating the second reference frequency according to the difference between the two divided data, and adaptively changing the received sensitivity intensity. 2Compensates for the deviation of the reception frequency by controlling the reference frequency.

[Important Uses of the Invention]

In a portable radiotelephone having a first frequency converting means and a second frequency converting means, the second reference frequency of the second frequency converting means can be adaptively controlled according to the reception sensitivity to finely adjust the frequency deviation.

Description

Receiving frequency compensation method and apparatus for portable radiotelephone

1 is a diagram showing the configuration of a receiver according to the present invention in the configuration of a portable radiotelephone.

2 is a flowchart illustrating a process of compensating for frequency deviation using a second reference frequency upon reception in a portable radiotelephone according to the present invention.

The present invention relates to a method and an apparatus for compensating for frequency deviation of a portable radiotelephone, and in particular, a receiver having a first frequency converting means and a second frequency converting means adaptively controls a second reference frequency according to a reception sensitivity. The present invention relates to a method and an apparatus capable of maintaining an optimal reception sensitivity.

In general, a portable radiotelephone is a mobile communication device and communicates wirelessly with a cell site allocated to a certain cell. Such a system is called a cellular system. The cellular system includes an ETACS system and an EAMPS system. The frequency synthesis in the portable radiotelephone synthesizes the required number of cellular systems (ETACS system = 1320, EAMPS system = 832) using a reference frequency.

The receiver of the conventional portable radiotelephone uses a superheterodyne receiver that converts the frequency of the signal received in two stages. In the portable radiotelephone using the super heterodyne method, the first reference frequency oscillator for performing the first frequency conversion uses a temperature compensated oscillator, and the second reference frequency oscillator for performing the second frequency conversion Use a common crystal oscillator. The first reference frequency converting means generates an intermediate frequency of the channel selected by the first reference frequency as the channel selection information, and the second frequency converting means is converted to demodulate the intermediate frequency received at the first stage. Generate a signal. In this case, the frequency deviation of the temperature compensated oscillator has a 2.5PPPM standard, so that the first reference frequency can be accurately generated, but the second reference frequency has a frequency deviation of 15PPM.

However, since the first reference frequency and the second reference frequency are fixed in the portable radiotelephone as described above, it is impossible to compensate for a frequency deviation caused by the surrounding environment. In particular, the means for generating the second reference frequency is very unstable in stability by using a general crystal oscillator. In addition, the frequency deviation is different according to each component constituting the portable radiotelephone, it is difficult to constant compensation. In addition, when a user uses a portable radiotelephone mounted in a vehicle, the frequency deviation becomes larger according to the Doppler effect, which causes noise to degrade the call quality.

Accordingly, an object of the present invention is to provide a method and apparatus for improving the call quality by compensating for the variation in frequency by analyzing the strength of a signal received from a portable radiotelephone.

Another object of the present invention is to adapt the second reference frequency of the second frequency conversion means by measuring the sensitivity of the signal received on the selected channel in the receiver of the portable radiotelephone having the first frequency conversion means and the second frequency conversion means. The present invention provides a method and an apparatus capable of always maintaining an optimal channel state while compensating for an amount of time.

Means for generating a first intermediate frequency by synthesizing the received radio signal and the first reference frequency to achieve the objects of the present invention, and the first intermediate frequency and the second reference frequency Means for generating a second intermediate frequency, means for detecting reception sensitivity at the second intermediate frequency, channel selection data for generating the first reference frequency, and generating the second reference frequency. Generating first and second division data, wherein the first sensitivity data is increased and the first sensitivity data is small when the reference sensitivity strength is large by comparing the reception sensitivity strength and the reference sensitivity strength. A reduction key for dispensing data comprises a control means and a phase synchronous loop means for loading the channel selection data to generate the first reference frequency. And means for loading the first and second divided data, respectively, and generating the second reference frequency according to the difference between the two divided data. The second reference frequency is adaptively controlled according to the change of to compensate for the deviation of the reception frequency.

In addition, in order to achieve the objects of the present invention, a method for compensating for frequency deviation in a portable radiotelephone includes generating a selected channel frequency as a first reference frequency, synthesizing a received radio signal with the first reference frequency, Generating an intermediate frequency; synthesizing the first intermediate frequency and the second reference frequency; generating a second intermediate frequency; detecting a reception sensitivity intensity at the second intermediate frequency; Comparing the reference sensitivity intensity, increasing the second reference frequency when the reference sensitivity intensity is large in the comparison process, and then returning to generating the second intermediate frequency; When the intensity is small, the process of returning to the process of generating the second intermediate frequency after reducing the second reference frequency And a gong.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

The term reception sensitivity used herein refers to a signal representing the strength of a reception signal detected by a current first reference frequency. The term reference sensitivity intensity is the strength of the received signal detected by the second intermediate frequency in the previous state. That is, the reception sensitivity strength of the previous state becomes the reference sensitivity strength in the next state.

1 is a block diagram of a receiver of a portable radiotelephone according to the present invention. A duplexer filter 11 is connected to an antenna and performs a function of separating a transmission radio signal and a reception radio signal. The low noise amplifier 12 is connected to the duplexer 11 and amplifies the received radio frequency RF of low strength with low noise. A band pass filer 13 is connected to the low noise amplifier 12 and filters and outputs the amplified radio signal RF into a signal band. Such a configuration becomes a means for receiving a radio signal.

In this case, in the case of the ETACS system, the frequency of the received radio signal RF is 917 MHz to 950 MHz. In this case, the band of the band filter 13 may be set to the frequency band of the corresponding system. At this time, the received signal has a deviation equal to the frequency deviation of the system.

The first mixer 14 receives a first local frequency LF1 and a radio signal RF, and mixes the two signals and outputs the mixed signals. The signal output from the first mixer 14 is | RF ± LF1 |. The band filter 15 filters the signal band RF-LF1 from the RF ± LF1 output from the first mixer 14 and outputs the signal at the first intermediate frequency IF1. Accordingly, the band filter 15 is a first intermediate frequency band filter for selectively filtering and outputting the first intermediate frequency IF1 at the output of the first mixer 14. The amplifier 16 is a first intermediate frequency amplifier for amplifying the first intermediate frequency IF1 output from the bandpass filter 15. This configuration is a first frequency converting means for converting the received radio signal RF into a first intermediate frequency IF1.

The second mixer 17 mixes and outputs the first intermediate frequency IF1 and the second reference frequency LF2 output from the amplifier 16. The signal output from the second mixer 17 is | IF1 ± LF2 |. The band filter 18 filters the | IF-LF2 | signal band from | IF ± LF2 | output from the first mixer 17 and outputs it to the second intermediate frequency IF2. Accordingly, the band filter 18 is a second intermediate frequency band filter for selectively filtering and outputting the second intermediate frequency IF2 at the output of the second mixer 18. The amplifier 19 is a first intermediate frequency amplifier for amplifying the second intermediate frequency IF2 output from the band filter 18. This configuration serves as a means for converting the first intermediate frequency IF1 to the second intermediate frequency IF2.

A RSSI detector 20 receives the output of the amplifier 19, detects the level of the second intermediate frequency IF2, and generates a reception sensitivity strength RSSI2. Here, the reception sensitivity strength RSSI2 represents the sensitivity strength of the signal detected at the current frequency and is used as a comparison sensitivity signal when the frequency deviation is corrected.

The band filter 21 receives the output of the RSSI detector 20 and outputs the filter in the band of the second intermediate frequency IF2. The demodulator 23 demodulates the signal of the second intermediate frequency band output to the band filter 21 and reproduces the original signal.

In the above configuration, the first mixer 17, the amplifier 19, the RSSI detector 20, the amplifier 22 and the demodulator 23 can use 606DK 'manufactured and sold by Philips as a demodulation integrated circuit.

The signal processor 24 digitally processes the demodulated signal output from the demodulator 23 and restores the original signal. The signal output from the demodulator 23 becomes a signal or voice of a portable radiotelephone. The signal processor 24 may use a digital signal processor.

An analog-to-digital converter 25 converts the received sensitivity strength RSSI into digital data. The controller 27 generates a channel selection data CS for generating a first reference frequency. The channel selection data CS is data for determining the frequency of the reception channel. In addition, the control unit 27 receives the output of the A / D converter 25 at a predetermined period, and receives the first division data N1 and the second division data N2 for generating a second reference frequency having the highest level of reception sensitivity in the selected channel. Occurs. Here, the second division data N2 means the division data for generating the second reference frequency, and the first division data N1 varies according to the change in the reception sensitivity, thereby changing the second reference frequency LF2. The memory 26 stores the reception sensitivity strength of the previous state output from the controller 27 as the reference sensitivity strength. Accordingly, the control unit 27 receives the received sensitivity strength and then compares it with the reference sensitivity strength, if the reference sensitivity strength is large, the first division data N1 is increased, and if the reference sensitivity strength is small, the first division data N1 is decreased. In addition, the received received sensitivity strength is stored as the reference sensitivity strength in the memory 26 to be used as the reference sensitivity strength of the next state. Such a configuration becomes a logic custom integrated circuit (Logiccustom IC).

The first reference frequency generator 40 loads the channel selection data CS output from the control unit 27. The first reference frequency generator 40 may be configured as a temperature compensated oscillator and a phase locked loop. In this case, the signal output from the temperature compensated oscillator becomes a reference clock for generating a first reference frequency LF1 and the channel selection data becomes a channel selection frequency. Accordingly, the first reference frequency generator 40 compares the clock output from the temperature compensated oscillator and the channel selection data to generate a first reference frequency LF1 according to the difference between the two signals.

The oscillator 31 is a temperature compensated oscillator and generates a reference clock signal for generating the second reference frequency LF2. The oscillator 31 generates a stable frequency in response to changes in the temperature of the surrounding environment, and has a frequency deviation of 2.5 PPM. The first frequency divider 32 loads the first frequency division data N1 output from the controller 27 and counts and outputs the frequency division data by the output of the oscillator 31. The second divider 33 loads the second divided data N2 output from the controller 27, and counts and outputs divided data by the second reference frequency LF2. The comparator 34 compares the outputs of the first divider 32 and the second divider 33 to generate a difference signal between the two signals. The amplifier 35 amplifies and outputs the output of the comparator 35. The low pass filter 36 receives the output of the amplifier 35 and generates a DC voltage. The voltage controlled oscillator 37 is oscillated according to the magnitude of the voltage output from the low pass filter 36 to generate the second reference frequency LF2. Such a configuration becomes a means for generating the second reference frequency LF2. Referring to the operation of issuing the second reference frequency LF2, the frequency division data value is increased or decreased according to the sensitivity strength of the received signal, and the second reference frequency LF2 is changed according to the change to adaptively adjust the frequency deviation. It can be seen that compensation. In the above configuration, the first divider 32, the second divider 33, the comparator 34 and the amplifier 35 are PLL integrated circuits, and MB15B01 manufactured and sold by Fujitsu Corporation can be used.

In the case of the ETACS system, the received signal RF output from the duplexer 11 is a signal having a band of 917 MHz to 950 MHz as described above. A portable radiotelephone employing a super heterodyne receiver includes a first frequency converting means and a second frequency converting means. At this time, the received signal RF is 917MHz-950MHz in the ETACS system. In addition, the first reference frequency LF1 output by the first reference frequency generator 40 to select a channel by the channel selection data CS output from the controller 27 has a range of 1009 MHz to 1042 MHz. Then, the first mixer 14 mixes the received signal RF and the first reference frequency LF 1, and the band filter 15 filters the low frequency from the mixed signal to generate a first intermediate frequency LF 1.

In the present invention, a means for generating the second reference frequency LF12 of the second frequency change means is implemented using a PLL. At this time, the PLL inputs the second divided data N2 for setting the second reference frequency LF2 and the first divided data N1 for controlling the deviation of the reference frequency to adaptively compensate for the frequency deviation caused by the surrounding environment. That is, the first division data N1, which is changed according to the change in reception sensitivity, and the second division data N2, which means the second reference frequency LF2, are compared, and the voltage controlled oscillator 37 is controlled according to the difference between the two division data so that the second reference Generate frequency LF2. At this time, the second reference frequency LF2 output from the voltage controlled oscillator 37 becomes 91.5325 MHz.

Then, the second mixer 17 mixes the first intermediate frequency IF1 and the second reference frequency LF2, and the band filter 18 filters the low frequency from the mixed signal to generate the second intermediate frequency IF2. In this case, the second intermediate frequency IF2 has a band of 455 kHz.

At this time, the RSSI detector 20 outputs a DC level according to the magnitude of the second intermediate frequency IF2 level. That is, the reception sensitivity strength RSSI2 is detected. The A / D converter 25 converts the reception sensitivity strength RSSI2 into digital data and outputs the digital data to the control unit 27. Then, the control unit 27 compares the reception sensitivity strength RSSI2 with the reference sensitivity strength RSSI1 to control the generation of the second reference frequency LF2. In this case, when the reference sensitivity strength RSSI1 is greater than the reception sensitivity strength RSSI2, the first division data N1 is increased. When the reference sensitivity strength RSSI1 is less than the reception sensitivity strength RSSI2, the first division data N1 is decreased. In the present invention, the amount of increase and decrease of the first frequency division data N1 is set to 100 Hz to finely adjust the deviation compensation of the first reference frequency LF1.

Referring to the flowchart of the frequency deviation compensation process according to the present invention in the portable radio telephone having the above configuration with reference to the flowchart of FIG. 2, first, the control unit 27 selects arbitrary channels while changing the channel selection data CS, and receives the selected channel. The received sensitivity strength RSSI2 is analyzed to determine whether a signal is detected on the selected channel. The beginning of the flowchart as shown in FIG. 2 shows a procedure of an operation of compensating for frequency deviation by measuring reception sensitivity of a selected channel in a state in which an arbitrary reception channel is set.

When the reception sensitivity is detected in the first selected channel, the control unit 27 determines the initial division ratio of the phase locked loop in order to generate the second reference frequency LF2 in step 211. That is, the controller 211 loads the first divided data N1 into the first divider 32 and the second divided data N2 into the second divider 33 in step 211. In this case, it is assumed that the oscillator 31 is a temperature compensated oscillator generating a frequency of 12.8 MHz, and that the second reference frequency LF2 is 91.5325 MHz. When the initial channel is selected, the first division data N1 may be set to 128,000 and the second division data N2 may be set to 915,5325.

When the first divided data N1 and the second divided data N2 are output as described above, the first divider 32 starts to count the clock output from the oscillator 31 after loading the first divided data N1. The divider 33 loads the second division data N2 and starts counting the second reference frequency LF2 output from the voltage controlled oscillator 37. The comparator 34 compares the divided signals output from the two frequency dividers 32 and 33, and outputs the low frequency filter 36. The low frequency filter 36 generates a voltage value according to the difference between the two divided signals. 2 Reference frequency LF2 is generated.

In this case, the first mixer 14 mixes the first reference frequency LF1 and the received signal RF, and the band filter 15 filters the low frequency intermediate frequency band from the mixed signal and selects and outputs the first intermediate frequency IF1. In addition, the second mixer 17 mixes the first intermediate frequency IF1 and the second intermediate frequency LF2, and the band filter 18 filters the low frequency intermediate frequency band from the mixed signal and selectively outputs the second intermediate frequency IF2. The RSSI detector 20 then detects the level of the second intermediate frequency to generate a reception sensitivity strength RSSI2. The A / D converter 25 converts the reception sensitivity strength RSSI2 into digital data and outputs the digital data.

In this case, the control unit 27 receives the reception sensitivity strength RSSI2 from the A / D converter 25 at a predetermined period in step 213, and stores the reception sensitivity strength RSSI2 received in step 215 as the reference sensitivity strength RSSI. In operation 217, the first dispensing data N 1 is increased. As described above, the reception of the received sensitivity strength RSSI2 is performed at regular intervals, and it can be seen that the RSSI2 received in the previous state is used as the reference sensitivity strength RSSI1 in the next state.

Here, the first intermediate frequency LF1 is 91.9875 MHz and the second intermediate frequency is demodulated to 455 kHz, but is not demodulated to the maximum level having a frequency deviation. Accordingly, the reception sensitivity RSSI2 value is also changed. Accordingly, when the RSSI2 is received, the controller 27 compares the RSSI] 2 currently received and the RSSI1 previously received and stored in step 221. In this case, if the value of the RSSI1 is greater than or equal to the value of the RSSI2, the RSSI2 is stored as the RSSI1 in the memory 26 in step 215, and the first division data N11 is increased by one in step 217. Here, the increase of the first division data N11 by 1 means that the second reference frequency LF2 is increased by 100 Hz. That is, when the second reference frequency LF2 that is currently generated is 91.5325 MHz, when the first frequency division data N11 is increased by one, the second reference frequency LF2 is changed to 91.5326 MHz by the PLL. This also increases the second intermediate frequency IF2 by 100 Hz.

In addition, as a result of comparing the RSSI2 currently received and the RSSI1 previously received and stored in step 221, if the value of the RSSI1 is smaller than the value of the RSSI2, the received RSSI2 is also stored in the memory 26 as the RSSI1 in step 223. In operation 225, the first dispensing data N 11 is decreased by one. Here, the increase of the first division data N11 by 1 means that the second reference frequency LF2 is decreased by 100 Hz. That is, when the second reference frequency LF2 currently generated is 91.5325 MHz, when the first division data N11 is increased by one, the second reference frequency LF2 is changed to 91.5324 MHz by the PLL. This also reduces the second intermediate frequency IF2 by 100 Hz.

Therefore, if an arbitrary channel is set, the control unit 27 receives the reception sensitivity strength RSSI2 at regular intervals, and then finely adjusts the first division data N11 by comparing the RSSI2 with the RSSI1 in a previous state. Accordingly, it can be seen that the first division data N11 performs a function of finely increasing or decreasing the division ratio of the oscillator 31 as a result. By repeating the above process, it is possible to demodulate a signal received at an optimal level in the selected channel by finely compensating for the deviation of the second reference frequency LF2 according to the change in reception sensitivity.

Claims (5)

A frequency compensating apparatus for a portable radio telephone, comprising: means for generating a first intermediate frequency by synthesizing a received radio signal and a first reference frequency, and synthesizing a second intermediate frequency by synthesizing the first intermediate frequency and the second reference frequency; Means for generating, means for detecting a reception sensitivity at the second intermediate frequency, generating channel selection data for generating the first reference frequency, first division data for generating the second reference frequency, and A control means for generating a second divided data, comparing the received sensitivity strength with the reference sensitivity strength, increasing the first divided data when the reference sensitivity strength is large, and decreasing the first divided data when the reference sensitivity strength is small; And phase synchronizing loop means, the means for loading the channel selection data to generate the first reference frequency, and phase synchronizing loop means. And first means for loading the first divided data and the second divided data, and generating the second reference frequency according to the difference between the two divided data, and adaptively adapted to the change in the received sensitivity intensity. A frequency compensating device of a portable radio telephone, characterized in that for compensating for the deviation of the reception frequency by controlling the reference frequency; The analog / digital converter of claim 1, wherein the control means converts the reception sensitivity into digital data. The first divided data corresponding to the reference clock and the second divided data corresponding to the second reference frequency are generated, and the received sensitivity intensity is detected at a set period and when the reference sensitivity intensity is large compared to the reference sensitivity intensity, A portable wireless telephone comprising: a control unit for increasing the first division data and decreasing the first division data when the reference sensitivity is small; and a memory for storing the reception sensitivity strength output from the control unit as the reference sensitivity strength. Frequency compensation device. 3. The apparatus of claim 2, wherein the means for generating the second reference frequency comprises: a temperature compensation type oscillator, A first divider which loads the first divided data and divides the output of the temperature compensated oscillator to generate a first divided signal, and loads the second divided data and divides the second reference frequency into a second A second divider for generating a divided signal, a comparator for comparing the first divided signal and the second divided signal, and generating a difference signal between the two divided signals, and converting the output of the comparator into a low-pass filter to DC voltage. And a low frequency filter and a voltage controlled oscillator controlled oscillated by the voltage to generate the second reference frequency. A first frequency converting means for generating a first intermediate frequency by mixing the first reference frequency and the received signal, and detecting a difference between the first divided signal and the second divided signal and setting a second reference frequency according to the difference between the two signals. And a second intermediate frequency converting means for generating a second frequency by mixing the second reference frequency and the first intermediate frequency, and a means for detecting the reception sensitivity of the second intermediate frequency. In the receiving method of claim 2, wherein the second divided signal is set to the second reference frequency and the first divided signal is set to the reference clock period to set the division ratio of the phase-locked loop, Comparing the reference sensitivity, and when the reference sensitivity is greater than the reception sensitivity, increasing the first divided signal and storing the reception sensitivity as the reference sensitivity. Waiting for input of the next reception sensitivity, and when the reference sensitivity is less than the reception sensitivity in the comparison process, the first divided signal is reduced and the reception sensitivity is stored as the reference sensitivity, and then the next reception sensitivity is used. And a process of waiting for the input of the input signal and repeating the reception sensitivity strength and the reference sensitivity strength after the waiting process is performed. A frequency compensation method of a portable radio telephone, comprising: generating a selected channel frequency as a first reference frequency; Generating a first intermediate frequency by synthesizing the received radio signal and the first reference frequency, generating a second intermediate frequency by synthesizing the first intermediate frequency and the second reference frequency, and generating the second intermediate frequency; Detecting a reception sensitivity at a frequency; comparing the reception sensitivity with a reference sensitivity; increasing the second reference frequency when the reference sensitivity is large in the comparison; And a process of returning to the process of generating the second intermediate frequency after reducing the second reference frequency when the reference sensitivity is small in the comparison process. Receiving method of the phone.