JP3180595B2 - Line quality measurement device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a satellite communication system, a mobile communication system, and a line quality measuring device for a receiver used in a mobile satellite communication system.

[0002]

2. Description of the Related Art FIG. 12 shows, for example, "B-355 QPSK line quality measurement using detection phase likelihood", Proceedings of the 1991 IEICE Spring Conference [Part 2] (1)
It is a block diagram which shows the conventional line quality measuring device as shown on page 355 on March 15, 991).

In FIG. 12, 1 is an input terminal of a phase-modulated received signal, 2 is a demodulator for demodulating the received signal, and 3 is whether or not the output signal point of the demodulator 2 is in a preset phase region. , And a phase region determination circuit 4 for outputting a detection signal.
5 is a bit error rate estimating circuit for estimating the bit error rate using the output value of the counter 4, and 6 is an output terminal for outputting the output value of the bit error rate estimating circuit 5 to the outside. .

Next, the operation will be described. The phase-modulated received signal is input from an input terminal 1 to a demodulator 2 and demodulated. Then, the demodulator 2 outputs the phase information at the determination point such as the Nyquist point to the phase region determination circuit 3. As an example, FIG. 10 shows a signal space diagram when a QPSK modulated signal is demodulated.

[0005] In FIG. 13, signal points when passing through an ideal transmission path are represented by S 1 to S 4 (π / 4, 3π / 4,
-3π / 4, -π / 4). However, when thermal noise or fading is added to the transmission path, the signal points are S1 to S1.
It deviates from the point of S4. If the phase is shifted by π / 4 or more from the original signal point, the quadrant of the signal point changes, resulting in a bit error.

Now, suppose that S1 is transmitted as a transmission phase and output from the demodulator 2 at the phase of point R. In this case, S
It is considered that the smaller the phase difference θ between the one point and the R point is, the lower the error rate is. On the contrary, when the error rate is poor, the frequency of signal points in the region near the I-axis / Q-axis shown by oblique lines in FIG. Get higher.

Therefore, the true bit error rate can be estimated by measuring the probability that the signal point enters the shaded area in FIG. Here, the probability that the signal point is in the shaded area in FIG. 13 is referred to as “pseudo error rate”. FIG. 14 shows an example of the relationship between the “pseudo error rate” and the “bit error rate”. If the "pseudo error rate" is obtained, the "bit error rate" can be estimated from FIG.

Next, when the phase point of the output signal of the demodulator 2 is detected in the shaded area of FIG.
The detection signal, that is, a pseudo error pulse is output. Then, the counter 14 counts the number of pseudo error pulses per unit time and inputs the count value to the bit error rate estimating circuit 5.

The bit error rate estimating circuit 5 calculates the “pseudo error rate” from the count value of the pseudo error pulses per unit time.
Is calculated, and the “bit error rate” is estimated from the result using the relationship shown in FIG.

As described above, the original "bit error rate" is estimated by measuring the "pseudo error rate" in which the phase at the decision point of the output signal of the demodulator 2 exists in the hatched portion as shown in FIG. Will be possible.

However, for example, it can be considered that a moving communication person is communicating through a fading transmission path and a stationary communication person is communicating through a Gaussian transmission path. The relationship with the "rate" changes depending on the state of the transmission path during this communication. Therefore, when the shaded area for outputting the pseudo error pulse is fixed as shown in FIG. 13, the relationship between the “pseudo error rate” and the “bit error rate” is as shown in FIG. Or fading transmission path, etc.
There is a problem that an accurate "bit error rate" cannot be estimated simply by measuring the "pseudo error rate".

[0012]

Since the conventional line quality measuring apparatus has the above configuration, the "pseudo error rate" depends on the state of a transmission line during communication such as a Gaussian transmission line or a fading transmission line. And the "bit error rate" is different, and there is a problem that an accurate "bit error rate" cannot be estimated by simply measuring the "pseudo error rate".

SUMMARY OF THE INVENTION The present invention has been made to solve the above-described problems, and has as its object to realize a line quality measuring apparatus that estimates a highly accurate "bit error rate" without depending on the state of a transmission line. I do.

[0014]

A channel quality measuring apparatus according to the present invention determines whether or not a demodulated signal output by a demodulating means is within a predetermined set phase area for a plurality of different set phase areas. Phase region determining means, a transmission path estimating means for estimating a transmission line state based on a plurality of phase determination signals corresponding to different set phase regions output from the phase region determining means, The error rate for the received signal is estimated according to the state of the transmission path.

Further, in the invention according to claim 2, the transmission path estimating means includes a counting means for counting a phase determination signal output from each of the phase area determining means for each unit time, and a counting value from the counting means. A pseudo error rate detecting means for detecting a pseudo error rate of the demodulation means output signal corresponding to each set phase area set in each phase area determining means; and a pseudo error rate from the pseudo error rate detecting means. And transmission line designating means for designating a transmission line state based on the relationship.

According to a third aspect of the present invention, there is further provided averaging means for averaging and outputting the count value outputted from the counting means, and the pseudo error rate detecting means is outputted from the averaging means. The pseudo error rate is detected based on the averaged count value.

Further, in the invention according to claim 4, three or more set phase regions are provided in the phase region determining means, and a phase determination signal corresponding to two of the set phase regions is provided in the transmission path estimating means. And selects one of a plurality of transmission path states estimated from the set of the phase determination signals in which the combination of the two set phase regions is different from each other, determines the estimated transmission path state, and outputs the selected transmission path state. In the invention according to claim 5, the transmission path designating means according to claims 2 and 3 is provided, wherein the pseudo error rate detecting means is configured to detect the pseudo error rate from the phase determination signals corresponding to two of the set phase regions. A candidate estimating means for estimating a transmission path state based on a relationship between the pseudo error rates to be detected, and a phase estimating means different in a combination of the two set phase regions estimated by the candidate estimating means. Which is constituted by a plurality of channel state candidates corresponding to the signal of the set and determining means for determining as the estimated channel state to select one by majority.

[0018]

According to the present invention, it is determined whether or not the demodulated signal is within a plurality of different set phase regions by the phase region determining means, and the transmission path estimating means determines whether the demodulated signal is within the plurality of set phase areas. , And the error rate estimating means estimates the error rate for the received signal in accordance with the estimated transmission path state. Is prevented.

According to the second aspect of the present invention, the counting means counts the phase judgment signal output from each of the phase area judging means for each unit time, and the pseudo error rate detecting means calculates the pseudo phase error based on the count value. , And the transmission path designation means estimates the transmission path state by designating the transmission path state based on the relationship between the pseudo error rates.

Further, in the invention according to claim 3, furthermore, the averaging means averages the count value from the counting means to suppress variations, and the pseudo error rate detecting means based on the averaged count value Detects accurate pseudo error rate,
As a result, the state of the transmission path is accurately estimated.

According to the fourth aspect of the present invention, it is determined whether or not the demodulated signal is within the region for three or more set phase regions by the phase region determining means. A transmission path state is estimated based on the phase determination signals corresponding to two of the areas, and one of a plurality of transmission path states estimated from a set of phase determination signals having different combinations of the set phase areas is selected. As a result, the estimated transmission path state is determined, so that the transmission path state can be accurately estimated. In the invention of claim 5, in particular, between the pseudo error rates corresponding to the two set phase regions. A plurality of transmission path state candidates based on the relationship are estimated by the candidate estimation means, and one of the plurality of transmission path state candidates is selected by majority decision from the plurality of transmission path state candidates and determined as the estimated transmission path state. It is.

[0022]

【Example】

Embodiment 1 FIG. 1 is a block diagram showing a configuration of a line quality measuring apparatus according to an embodiment of the present invention. In FIG. As described above, conventionally, the relationship between the pseudo error rate and the bit error rate is different between the Gaussian transmission path and the fading transmission path, and it is not possible to accurately estimate the bit error rate by simply measuring the pseudo error rate. There was a point. The present invention measures a plurality of types of pseudo error rates in a plurality of types of phase regions, estimates a transmission path state by using the same, and estimates a bit error rate with high accuracy using the results.

The circuit shown in FIG. 1 is configured as follows. 10 to 12 indicate whether the phase at the decision point of the demodulated signal output from the demodulator 2 is within a predetermined set phase region,
First, second, and third phase region determination circuits serving as phase region determination means for determining different set phase regions.

These first, second and third phase domain circuits 1
The set phase regions at 0 to 12 are respectively shown in FIG.
(B) and (c) are areas indicated by oblique lines (hereinafter referred to as “area 1”, “area 2”, and “area 3”, respectively). When the phase is within these set phase regions, a pseudo error pulse is output as a phase determination signal.

Reference numerals 13 to 15 denote the above-mentioned phase region determination circuits 10
The first, second, and third counters 16 as counting means for counting the pseudo error pulses output from the counters 12 to 12 for each unit time are provided with the count value output from the second counter 14 and the third counter. The counter 15 is a transmission path estimating circuit that estimates a transmission path state using the output count value.

Reference numeral 100 denotes the second and third phase domain circuits 1
Transmission path estimating means for estimating the state of the transmission path based on the phase determination signals output from 1 and 12, and includes the second and third counters and the transmission path estimating circuit 16.

The transmission line estimating circuit 16 is constructed as shown in FIG.
The demodulated signal of the demodulating means 2 corresponding to each of the set phase regions "region 2" and "region 3" set in each of the phase region determination circuits 11 and 12 from the count values of the pseudo error pulses from Nos. 4 and 15. Pseudo error rate detecting means 1 for detecting pseudo error rate
6a and a transmission path designating means 16b for designating a transmission path state based on the relationship between the pseudo error rates from the pseudo error rate detecting means 16a.

Reference numeral 17 denotes a bit error rate estimating means for estimating an error rate for a received signal in accordance with the transmission path state estimated by the transmission path estimating means 100. The bit error rate is estimated based on the number of pseudo error pulses corresponding to the “region 1” from the first counter 13 while corresponding to the state.

Next, the operation will be described. First, the demodulated signal output from the demodulator 2 is branched into three and input to the first, second, and third phase domain determination circuits 10 to 12, respectively. First, second, and third phase region determination circuits 10-1
2 includes different set phase regions “region 1” as indicated by hatched portions in FIGS. 2A, 2B, and 2C as described above,
“Region 2” and “Region 3” are set, and each of the phase region determination circuits 10 to 12 is set to “Region 1”.
When the demodulated signal point from the demodulator 2 exists in “region 2” and “region 3”, the detection pulse, that is, the first, second, and third pseudo error pulses are output.

The first, second, and third counters 13, 14,
Reference numeral 15 counts the first, second, and third numbers of pseudo error pulses per unit time. The count value of the first counter 13 is sent to the bit error rate estimating means 17 and
The count values of the second and third counters 14 and 15 are input to the transmission path estimation circuit 16.

In the transmission path estimating circuit 16, the pseudo error rate detecting means 16a calculates the pseudo error rates 2 and 3 from the count values input from the second and third counters 14 and 15, and outputs the pseudo error rates to the transmission path specifying means 16b. I do. Second and third counters 14, 1
The number of pseudo error pulses per unit time output from the count value of 5 may be used as the pseudo error rate.

FIG. 4 shows the relationship between the pseudo error rate 2 and the pseudo error rate 3 when “region 2” and “region 3” are as shown by the hatched portions in FIG. As can be seen from FIG. 4, the "pseudo error rate 2 / pseudo error rate 3" characteristic shows different characteristics between the Gaussian transmission path and the fading transmission path. Such characteristics can be obtained by measurement or simulation.

However, since the pseudo error rate 2 and the pseudo error rate 3 are both numerical values measured as described above, the relationship between the measured pseudo error rate 2 and the pseudo error rate 3 is shown in FIG. By comparing the “pseudo error rate 2 / pseudo error rate 3” characteristic, it can be estimated whether the transmission path is a Gaussian transmission path or a fading transmission path.

Thus, the pseudo error rate detecting means 16
transmission path designating means 1 based on the pseudo error rates 2 and 3 from
6b estimates the transmission path state. For example, if it is determined whether the detected pseudo error rate 3 corresponding to the detected pseudo error rate 2 is closer to the characteristic of the Gaussian transmission path or the characteristic of the fading transmission path in FIG. So you can
The pseudo error rate 2 is divided for each predetermined range,
6b has a table of each range and a threshold value corresponding to this range, finds a corresponding threshold value from the detected pseudo error rate 2, and calculates the threshold value and the detected pseudo error rate 3
Can be estimated as a transmission path by comparing

Thus, the transmission path estimation circuit 16 estimates the state of the transmission path, and outputs the transmission path estimation transmission path signal to the bit error rate estimating section 17.

The bit error rate estimating unit 17 performs the operation for the Gaussian transmission path and the fading transmission path as shown in FIG.
Kinds of “pseudo error rate 1 / bit error rate” characteristics are stored in advance. Then, the bit error rate estimating unit 17 selects which of the two types of “pseudo error rate 1 / bit error rate” characteristics to use using the transmission path estimation transmission path signal output from the transmission path estimation circuit 16. Then, using the selected “pseudo error rate 1 / bit error rate” characteristic and the measured pseudo error rate 1, a more accurate “bit error rate” is estimated.

The error rate estimating means 17 stores, for example, a plurality of tables of [pseudo error rate-bit error rate] corresponding to the state of the transmission path, and calculates the bit error rate according to the output of the transmission path estimating means. A table for estimation may be selected, and the bit error rate may be obtained from the pseudo error rate using the selected table. Alternatively, a plurality of [pseudo error rate−bit error rate function] corresponding to the transmission path state may be determined. May be stored, a function for estimating the bit error rate may be selected according to the output of the transmission path estimating means, and the bit error rate may be calculated from the pseudo error rate using the selected function.

As described above, according to this embodiment, a plurality of types of pseudo error rates for a plurality of types of set phase regions are measured, a transmission path state is estimated based on a relationship between the pseudo error rates, and the result is used. To estimate the bit error rate,
Highly accurate bit error rate estimation becomes possible.

Although the above embodiment has been described with respect to a configuration in which the three phase region determination circuits 10 to 12 are provided as the phase region determination means, the phase region determination means only needs to determine the demodulated signal for at least two set phase regions. If this is the case, the transmission path can be estimated. Therefore, the configuration shown in FIG. 6 may be used, and in this case, the configuration can be simplified.

However, in order to estimate the transmission path, as shown in FIG. 2B and FIG. 2C set in the second and third phase region determination circuits 11 and 12 in the above embodiment, two settings are made. The larger the difference between the widths of the phase regions, the better the accuracy. In order to estimate the bit error rate, as shown in FIG. 2A set in the first phase region determination circuit 10 in the above embodiment. In some cases, the phase region set to a medium width has higher accuracy. Therefore, FIG.
In the case of the configuration of (1), the first phase region determination circuit 10 is used for the estimation of the transmission path and the estimation of the bit error rate. It is necessary to decide with consideration.

Embodiment 2 FIG. 7 is a block diagram showing a configuration of a line quality measuring apparatus according to Embodiment 2, in which the same components as those in the above embodiment are indicated by the same symbols. In this embodiment, the bit error rate is more accurately estimated by using data obtained by averaging the pseudo error rates (the pseudo error rates 2 and 3 in the first embodiment) used for the transmission path estimation. Is what you do.

Reference numerals 20 and 21 denote first averaging circuits for averaging the count values of the second and third counters 14, respectively. Next, the operation of the second embodiment will be described. In Example 1,
Since the unit time counted by the first, second, and third counters 13, 14, and 15 is finite, the “pseudo error rate 2 / pseudo error rate 3” shown in FIG. As shown in FIG. 8, the characteristics in the Gaussian transmission path and the characteristics in the fading transmission path overlap, and an area where it is impossible to determine which of the transmission paths is generated.

Therefore, in order to suppress this data variation, the count values output by the second and third counters 14 are averaged by the first and second averaging circuits 20 and 21 as shown in FIG. The pseudo error rate 2 / pseudo error rate 3 is obtained in the transmission path estimation circuit 16 from the averaged count value. As a result, the “pseudo error rate 2 / pseudo error rate 3” characteristic has a reduced variation as shown in FIG. 9, so that the accuracy of transmission path estimation can be improved.

As described above, in the second embodiment, the transmission error estimation accuracy is improved by making it possible to use more averaged data for the pseudo error rate used for the transmission channel estimation. This enables highly accurate bit error rate estimation. The first and second averaging circuits 20, 2
The average number of 1 may be variable.

Third Embodiment FIG. 10 is a block diagram showing a configuration of a line quality measuring apparatus according to a third embodiment. In FIG. 10, the same components as those in the above embodiment are denoted by the same reference numerals. In this embodiment, when estimating a transmission path, first, phase determination is performed for three phase determination areas, a transmission path state is estimated by combining two of them, and a plurality of transmission path state candidates are estimated. Is used to obtain the final transmission path estimation result by majority logic, thereby improving the transmission path estimation accuracy and estimating the bit error rate with higher accuracy.

The circuit shown in FIG. 10 is configured as follows. The transmission path estimating means 100 includes the second and third counters 1
4 and 15 and a majority logic transmission path estimating circuit 30. The majority logic type transmission path estimation circuit 30 has a configuration shown in FIG.

30a is a first, second, and third counter 1
From the count values of the pseudo error pulses from 3, 14, and 15, corresponding to, for example, each of the set phase regions "region 1", "region 2", and "region 3" in FIG. A pseudo error rate detecting means 30b for detecting a pseudo error rate of the demodulated signal of the demodulating means 2 and a transmission path designation for designating a transmission path state based on a pseudo error rate relation from the pseudo error rate detection means 30a. Means.

The transmission path designating means 30b further comprises a candidate estimating means 30c and a deciding means 30d. The candidate estimating means 30c uses two of the three types of pseudo error rates input from the pseudo error rate detecting means 30a and estimates transmission path state candidates based on the relationship. And outputs the result to the determination means 30d. In this case, three candidates are output. Determination means 3
0d selects one of the three candidates by majority decision and determines it as an estimated transmission path state.

Next, the operation will be described. First, second,
The count values output from the third counters 13 to 15 are input to the pseudo error rate detection means 30a, where the pseudo error rates are respectively detected. These three pseudo error rates are input to the candidate estimating means 30c, and by using two of the pseudo error rates, as in the first embodiment, from the relationship between the pseudo error rates,
Estimate transmission path state candidates. Estimation of the transmission path state candidates is performed in three ways for combinations having different pseudo error rates, and three candidates are output. Then, from the three candidates, the determination means 30d determines the final transmission path estimation result by majority logic and outputs the result.

As described above, according to the third embodiment, when estimating a transmission path, first, phase determination is performed for three phase determination areas, and two of them are combined to estimate a transmission path state, and a plurality of transmission path states are estimated. Is estimated, and the result is used as a final transmission path estimation result by majority logic, thereby improving the transmission path estimation accuracy and estimating the bit error rate with higher accuracy.

It should be noted that a plurality of types of pseudo error rates may be input to the bit error rate estimating unit 17 and the bit error rate may be estimated using majority logic.

In all of the above embodiments, the bit error rate estimating section 17 estimates the bit error rate based on the determination signal output from the first phase region determination circuit 10. It is sufficient if the bit error rate is estimated based on a change in the phase of the signal. By controlling the characteristics of the bit error rate estimation based on the transmission path state estimated by the transmission path estimation means, the bit error rate estimation can be performed with high accuracy. Becomes possible. Each unit may be realized by signal processing by software.

[0053]

As described above, according to the present invention, a phase region determining means for determining whether or not a demodulated signal is within a set phase region for a plurality of different set phase regions, Since transmission path estimation means for estimating a transmission path state based on a plurality of corresponding phase determination signals and transmission path estimating means for estimating an error rate for the received signal according to the estimated transmission path state are provided, Regardless of the road condition,
The bit error rate can be estimated with high accuracy.

According to the second aspect of the present invention, there is provided a counting means for counting the phase judgment signal from each of the phase area judging means for each unit time, and each of the respective phase area judging means set from the count value. A pseudo error rate detecting means for detecting a pseudo error rate of the demodulated signal corresponding to a set phase region; and a transmission path designating means for designating a transmission path state based on a relationship between the pseudo error rates, the transmission path Estimation means can be configured,
A device capable of estimating the bit error rate with high accuracy regardless of the transmission path state can be realized.

According to the third aspect of the present invention, by further providing averaging means for averaging the count value,
Variations in the count value are suppressed, and the pseudo error rate detection means can detect the pseudo error rate with high accuracy based on the averaged count value, can estimate the state of the transmission path with high accuracy, and achieve high bit accuracy. The error rate can be estimated.

In the invention according to claims 4 and 5, three or more of the set phase regions in the phase region determining means are provided,
The transmission path estimating means estimates a transmission path state based on the phase determination signals corresponding to two of the set phase areas, and sets the phase determination signal based on a different combination of the two set phase areas. Since one is selected from a plurality of estimated transmission path states and determined and output as an estimated transmission path state, the transmission path state can be accurately estimated, and the bit error rate can be estimated with high accuracy. it can.

[0057]

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of a line quality measuring device according to a first embodiment of the present invention.

FIG. 2 is an explanatory diagram illustrating an example of a set phase region in a phase region determination.

FIG. 3 is a block diagram illustrating a configuration of a transmission path estimation circuit according to the first embodiment.

FIG. 4 is an explanatory diagram showing an example of a pseudo error rate 2 / pseudo error rate 3 characteristic used for transmission path estimation.

FIG. 5 is an explanatory diagram showing an example of a pseudo error rate 1 / bit error rate characteristic used for bit error rate estimation.

FIG. 6 is a block diagram showing a configuration of a line quality measuring device according to another embodiment of the present invention.

FIG. 7 is a block diagram illustrating a configuration of a line quality measuring device according to a second embodiment of the present invention.

FIG. 8 is an explanatory diagram showing an example of a pseudo error rate 2 / pseudo error rate 3 characteristic.

FIG. 9 shows a pseudo error rate 2 after averaging used for channel estimation.
FIG. 3 is an explanatory diagram showing a characteristic of a pseudo error rate 3.

FIG. 10 is a block diagram illustrating a configuration of a line quality measuring device according to a third embodiment of the present invention.

FIG. 11 is a block diagram illustrating a configuration of a majority logic transmission path estimating circuit according to a third embodiment.

FIG. 12 is a configuration block diagram illustrating a configuration example of a conventional line quality measurement device.

FIG. 13 is an explanatory diagram illustrating an example of a set phase region in the phase region determination.

FIG. 14 is an explanatory diagram showing an example of a pseudo error rate / bit error rate characteristic used for bit error rate estimation.

FIG. 15 is an explanatory diagram showing an example of pseudo error rate / bit error rate characteristics in different transmission paths.

[Explanation of symbols]

 Reference Signs List 1 input terminal 2 demodulator 6 output terminal 10 first phase region determination circuit 11 second phase region determination circuit 12 third phase region determination circuit 13 first counter 14 second counter 15 third counter 16 transmission Path estimation circuit 16a pseudo error rate detection means 16b transmission path specification means 17 bit error rate estimation means 20 first averaging circuit 21 second averaging circuit 30 majority logic type transmission path estimation circuit 30a pseudo error rate detection means 30b transmission path specification Means 30c Candidate estimation means 30d Decision means 100 Transmission path estimation unit

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI H04B 7/005 H04B 7/005 (56) References JP-A-3-222554 (JP, A) JP-A-58-182356 (JP) , A) JP-A-56-1644 (JP, A) "QPSK link quality measurement using detection phase likelihood", Proc. Of the 1991 IEICE Spring Conference, March 15, 1991, separate volume 2, B-355 (58) Field surveyed (Int. Cl. ⁷ , DB name) H04L 27/00-27/38

Claims (5)

(57) [Claims] 1. A demodulation means for demodulating a received signal, and a phase region determination for judging whether or not a demodulated signal output by the demodulation means is within a predetermined set phase region for a plurality of different set phase regions. Means, transmission path estimation means for estimating a transmission path state based on a plurality of phase judgment signals corresponding to different set phase areas output from the phase area judgment means, and transmission path state estimated by the transmission path estimation means An error rate estimating means for estimating an error rate of the received signal in accordance with the channel quality measurement apparatus. 2. The transmission path estimating means includes: a counting means for counting a phase determination signal output from each of the phase region determining means for each unit time; A pseudo error rate detection means for detecting a pseudo error rate of the demodulation means output signal corresponding to each of the set phase regions set in the means, and transmission based on a relationship between the pseudo error rates from the pseudo error rate detection means. 2. The line quality measuring apparatus according to claim 1, further comprising a transmission path specifying means for specifying a path state. 3. An averaging means for averaging the count value output from the counting means and outputting the averaged value, wherein the pseudo error rate detecting means is based on the averaged count value output from the averaging means. 3. The channel quality measuring device according to claim 2, wherein a pseudo error rate is detected. 4. The apparatus according to claim 1, wherein three or more set phase regions are provided in said phase region determining means, and said transmission path estimating means estimates a transmission path state based on phase determination signals corresponding to two of said set phase areas. And selecting one of a plurality of transmission path states estimated from a set of the phase determination signals having different combinations of the two set phase regions, determining the state as an estimated transmission path state, and outputting the estimated transmission path state. The line quality measuring device according to claim 1. 5. The apparatus according to claim 1, wherein said phase domain determination means comprises three or more said set phase domains, and said transmission path designating means comprises a pseudo error rate detection means based on phase determination signals corresponding to two of said set phase domains. Corresponds to a set of candidate phase estimating means for estimating a transmission path state based on a relationship between the pseudo error rates detected by the method, and a set of the phase determination signals different in combination of the two set phase regions estimated by the candidate estimating means. 4. The line quality measuring apparatus according to claim 2, further comprising: a determination unit that selects one of a plurality of transmission path state candidates to be determined by majority decision and determines the selected transmission path state as an estimated transmission path state.