JP3388420B2 - Frequency control method in wireless terminal system - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to TDs such as PHSs (simple mobile phones) and PDCs (personal digital cellular).
The present invention relates to a frequency control method in a wireless terminal system using MA (Time Division Multiple Access).

[0002]

2. Description of the Related Art Conventionally, in a radio telephone system using TDMA such as PHS and PDC, AFC (automatic frequency control) is usually used to adjust the own reception reference frequency to a more ideal reception state to the frequency of the received signal. The function is adopted. FIG. 4 is a diagram showing a configuration example of a conventional frequency control method. As shown in the figure, the conventional frequency control method includes an antenna 1, an RF unit 2, a demodulator unit 3, a frequency control unit 4, a D / A conversion unit 5, an oscillator 6, and the like. In FIG. 4, parts other than frequency control are omitted.

In the above structure, the radio wave received by the antenna 1 is amplified by the RF section 2 and input to the demodulator section 3. The demodulator section 3 obtains a frequency deviation f from the oscillation frequency of the oscillator 6 and inputs it to the frequency control section 4. The frequency control unit 4 performs processing such as amplification on the signal of the frequency deviation f, controls the oscillation frequency (reception reference frequency) of the oscillator 6 via the D / A conversion unit 5, and controls the frequency deviation f in a decreasing direction. .

As described above, the conventional AFC function always keeps the wireless reception state ideal to improve the bit error rate and the reception sensitivity by adjusting its own reception reference frequency to the received frequency. .

[0005]

However, the radio wave reception state is not always in a good state, but the frequency detection may show an abnormal value due to the influence of jamming radio waves and the like. In the above-mentioned conventional technology, when the frequency detection shows an abnormal value due to the influence of jamming radio waves, the AFC function works to adjust its own reception reference frequency to the abnormal value, and the deviation from the frequency that should be originally received is generated. However, there is a problem in that the bit error rate increases as a result, and in the worst case, the synchronization is lost and the radio release state occurs.

The present invention has been made in view of the above points, and when a radio wave is poorly received due to an interfering radio wave or the like, the AFC function is automatically turned off and the reception reference frequency of the radio terminal itself is maintained, whereby a predetermined radio wave is received. An object of the present invention is to provide a frequency control method in a wireless terminal system that maintains a reception state of radio waves.

[0007]

In order to solve the above-mentioned problems, the invention according to claim 1 is to provide an oscillator for oscillating a reception reference frequency, a frequency deviation for detecting a frequency deviation between the frequency of a received radio wave and the reception reference frequency. A radio comprising a detection means and a frequency control means for controlling the oscillation frequency of the oscillator, and the frequency control means controls the oscillator using the frequency deviation as a control signal to adjust the reception reference frequency to receive a predetermined radio wave signal. In the frequency control method in the terminal system, a means for obtaining a reception quality parameter indicating the reception state of the radio wave is provided, and the frequency control means determines the quality of the reception state by the reception quality parameter, and when the reception state is bad, the frequency is determined. Decrease the deviation control signal and, when the reception condition is good, amplify the frequency deviation control signal and adjust the reference frequency to receive the specified radio signal. It is characterized in.

According to a second aspect of the present invention, in the frequency control method in the wireless terminal system according to the first aspect, the aperture value of the eye pattern is obtained as a reception quality parameter, and the product of the aperture value and the frequency deviation is obtained. Then, the oscillator is controlled by using the product of the aperture value and the frequency deviation as a control signal, the reference frequency is adjusted, and a predetermined radio wave signal is received.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 is a diagram showing a configuration example of a frequency control method of the present invention. As shown in the figure, the frequency control method is provided with a multiplier 4-1 in the frequency control unit 4,
The demodulator section 3 obtains an aperture value k (details described later) of the eye pattern as a reception quality parameter in addition to the frequency deviation f, and controls the frequency of the oscillator 6 using the product of the frequency deviation f and the aperture value k as a control signal. Is the way to do it. In FIG. 1, the frequency control unit 4 is a unit having the same function as the frequency control unit of FIG. 4 except that the multiplier 4-1 is provided, and the description thereof is omitted here.

FIG. 2 is an explanatory diagram of the aperture value k indicating the quality of the reception quality, 2-1 shows the waveform of the transmission signal, and 2-2 shows the eye pattern of the reception signal when the reception state is good. Two
Reference numeral -3 indicates an eye pattern of the received signal when the reception state is poor. As shown in the waveform 2-1 of the transmission signal in FIG. 2, since the digital signal a, which is the transmission signal, is transmitted in the determined frequency band (narrow band), the sampling point d (cycle c) like the transmission signal b. And transmitted as a smooth waveform.

On the side of the receiver such as PHS or PDC, the demodulator unit 3 has an eye pattern 2-2 of the received signal when the reception state is good as shown in FIG. 2 and an eye pattern 2 of the reception signal when the reception state is bad as shown in FIG. As shown by -3, at the sampling point d, 1 and -1 are randomly taken and the signals are superposed to form an eye pattern, and the aperture value k is obtained. Eye pattern at sampling point d
The width of the space (also referred to as the aperture value k or eye aperture) is seen from the superimposed waveforms, but in practice, it is calculated by taking a plurality of average values or variations. When the reception state is good, as shown in the eye pattern 2-2 of the reception signal in FIG. 2, there is little variation at the sampling point d, the aperture value k is large, and the error rate of the digital reception signal (0, 1) is small. Become. On the other hand, when the reception state is poor, there are many variations at the sampling points d as shown in the reception signal eye pattern 2-3 of FIG.
The error rate of the digital received signal (0, 1) becomes large. FIG. 3 is a diagram showing the relationship between the reception quality of received radio waves and the aperture value k. From the above, the aperture value k is a parameter indicating the reception quality.
Can be used as a data.

As described above, in the present embodiment, the multiplier 4-1 of the frequency control unit 4 sets the aperture value k, which is a radio wave reception quality parameter, and the frequency deviation f (difference between the reference frequency and the reception frequency). The product is obtained, and the value is used as a control signal to control the frequency (reception reference frequency) of the oscillator 6 via the D / A converter 5. Therefore, when the reception quality of the radio wave is poor due to an interference radio wave or the like, the control signal becomes small and the influence of the abnormal reception radio wave becomes small. On the contrary, when the reception quality of the radio wave is good, the control signal becomes larger and the oscillation frequency of the oscillator 6 can be quickly adjusted to a predetermined reception frequency.

Although the aperture value k is used as the reception quality parameter in the above embodiment, the present invention is not limited to this as long as the data represents the reception quality.

[0014]

As described above, according to the present invention, the quality of the radio wave reception condition is judged by the radio wave reception quality parameter, and when the reception condition is poor, the control signal of the frequency deviation is reduced and reception is performed. When the condition is good, the control signal of the frequency deviation is amplified and the reception reference frequency is adjusted to receive the predetermined radio wave signal, so when the reception quality of the radio wave is poor due to jamming radio waves, the control signal becomes small and abnormal reception occurs. When the influence of the radio wave is reduced, on the contrary, when the reception quality of the radio wave is good, the control signal becomes large, and the excellent effect that the predetermined reception frequency can be quickly achieved is obtained.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration example of a frequency control method of the present invention.

FIG. 2 is an explanatory diagram of an aperture value indicating the quality of reception quality.

FIG. 3 is a diagram showing the relationship between reception quality and aperture value.

FIG. 4 is a diagram showing a configuration example of a conventional frequency control method.

[Explanation of symbols]

1 antenna 2 RF section 3 Demodulator section 4 Frequency control section 4-1 Multiplier 5 D / A converter 6 oscillators f Frequency deviation k opening value

─────────────────────────────────────────────────── ─── Continuation of the front page (56) Reference JP-A-7-297779 (JP, A) JP-A-5-308253 (JP, A) JP-A-7-58600 (JP, A) JP-A-8- 288796 (JP, A) JP-A-7-273823 (JP, A) JP-A-1-154660 (JP, A) JP-A-6-120996 (JP, A) JP-A-6-268696 (JP, A) (58) Fields surveyed (Int.Cl. ⁷ , DB name) H03J 7/02 H04B 1/16

Claims (2)

(57) [Claims] 1. An oscillator for oscillating a reception reference frequency, a frequency deviation detecting means for detecting a frequency deviation between the frequency of a received radio wave and the reception reference frequency, and a frequency control means for controlling an oscillation frequency of the oscillator, In a frequency control method in a wireless terminal system configured to control the oscillator using the frequency deviation as a control signal by the frequency control means to adjust a reception reference frequency and receive a predetermined radio signal, a reception quality indicating a reception state of a radio wave. A means for determining parameters is provided, and the frequency control means determines whether the reception condition is good or bad by the reception quality parameter.When the reception condition is bad, the frequency deviation control signal is reduced, and when the reception condition is good. Is a radio terminal characterized by amplifying the control signal of the frequency deviation and adjusting the reception reference frequency to receive a predetermined radio wave signal. Frequency control method in the system. 2. An aperture value of an eye pattern is obtained as the reception quality parameter, a product of the aperture value and the frequency deviation is obtained, and the oscillator is controlled by using a product of the aperture value and the frequency deviation as a control signal. The frequency control method in the wireless terminal system according to claim 1, wherein the reception reference frequency is adjusted to receive a predetermined radio wave signal.