JP2001308945A - Multi-pilot tone detection method and matching filter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a multi-pilot tone detection method and a matching filter by which a filter circuit scale can be reduced in the case that a preamble signal consists of a multi-pilot tone signal. SOLUTION: The matching filter detecting multi-pilot tone signals (f1+f2+...+fn) and in matching with the multi-pilot tone signals (f1+f2+...+fn) of a detection object is configured with filters that are matched with each pilot tone signal of the multi-pilot tone signals (f1+f2+...+fn).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a matched filter technology for detecting a multi-pilot tone signal, and more particularly, to a multi-filter capable of reducing the circuit scale of a filter when a preamble signal is composed of a multi-pilot tone signal. The present invention relates to a pilot tone detection method and a matched filter.

[0002]

2. Description of the Related Art Conventionally, in a matched filter for detecting a multi-pilot tone signal, in order to demodulate a burst signal, a synchronization process for detecting the head of the burst signal is required. In many cases, a fixed preamble is added to the head of a burst signal for the purpose of facilitating synchronization processing. Since the preamble signal is fixed for each burst signal, preamble detection can be performed by using a filter matched to the preamble signal (first related art).

In addition, an FIR filter (Finite I)
As a conventional technique for reducing the circuit scale of a pulse response filter (a finite response filter), there is a technique described in Japanese Patent Application Laid-Open No. 9-98069 (second conventional technique). In other words, the second prior art employs an FIR in which the circuit scale of the tap coefficient processing unit is reduced while maintaining the same filter characteristics as the prior art.
And a shift register having m stages for inputting and shifting an input digital signal in synchronization with a clock ck, and dividing each stage of the shift register into a preceding stage and a succeeding stage. A selector for alternately selecting and outputting the output of the preceding stage and the output of the succeeding stage by the double frequency clock ck2, and a tap coefficient processing unit for performing tap coefficient processing on the output of the preceding stage and the succeeding stage of the shift register alternately input from the selector. A delay register for temporarily storing the output of the tap coefficient processing unit and delaying the output by one clock ck2 for output, and adding the output of the delay register and the output of the tap coefficient processing unit to output the operation result for all stages of the shift register And an output register that outputs the operation result from the adder as a filter output in synchronization with the clock ck. , And to process the tap coefficients by dividing each stage of the shift register to the front and rear stages. Also, the tap coefficient processing unit stores a tap coefficient ROM for storing a preset tap coefficient, and outputs of the preceding and succeeding stages of the shift register and the tap coefficient ROM alternately selected by selectors respectively corresponding to the respective stages of the shift register. , And a full adder for summing the outputs of the multipliers, wherein the number of multipliers corresponds to substantially half of each stage of the shift register. Also,
As a tap coefficient processing unit, all operation results to be obtained by performing tap coefficient processing on the output of the shift register are stored, and the operation results stored by alternately using the outputs of the previous and subsequent stages of the shift register as addresses are stored. Is provided.

Thus, the output of the shift register is used for multiplication by half using a selector having a small circuit scale, so that the multiplier having a large circuit scale is reduced to approximately half, and the storage capacity of the tap coefficient ROM is reduced. And the number of data additions of the full adder can be greatly reduced, so that the same filter characteristics as those of the prior art can be obtained, and as a whole, the circuit scale can be greatly reduced, and further, the circuit scale can be reduced. Accordingly, it is possible to provide an FIR type digital filter suitable for LSI. In addition, since the result of the tap coefficient processing is stored in advance in the operation result ROM and the output of the shift register is used as the address, the tap coefficient ROM, the multiplier, and the full adder are all deleted. In addition, since an optimum operation result can be calculated in advance, it is possible to output a filter characteristic with less deterioration due to the operation process in combination with the simplification of the circuit configuration by using a simple address. Such effects are disclosed.

[0005]

However, the first prior art filter matched to the preamble signal has the following problems.
In general, the filter is composed of an FIR filter. However, in a preamble based on a multi-pilot tone signal, the time waveform of the preamble has a complicated waveform. Therefore, when the tap coefficients are realized with a small number of bits, the filter output rapidly deteriorates. Therefore, there is a problem that it is necessary to increase the bit width of the tap coefficient, and it is difficult to reduce the circuit scale of the multiplier that multiplies the main signal by the tap coefficient. Furthermore, since a plurality of multipliers are often used in a matched filter, and the circuit size of the multiplier affects the circuit size of the entire filter, the circuit size of the filter matched to the multi-pilot tone signal is increased. There was a point.

The second prior art uses the symmetry of the tap coefficient of the FIR filter, and has a problem that it is difficult to reduce the circuit scale of the multiplier itself.

The present invention has been made in view of such a problem, and an object thereof is to reduce the circuit size of a filter when a preamble signal is composed of a multi-pilot tone signal. An object of the present invention is to provide a multi-pilot tone detection method and a matched filter.

[0008]

The gist of the present invention is that a filter matched with a multi-pilot tone signal to be detected is replaced with a filter matched with the multi-pilot tone signal to be detected. A multi-pilot tone detection method is characterized in that the pilot tone signal is divided into filters matched with the respective pilot tone signals. Claim 2
The gist of the invention described in (1) is that, for a matched filter for detecting a multi-pilot tone signal, a filter matched to the multi-pilot tone signal to be detected is divided into a plurality of filters. The present invention resides in a pilot tone detection method. The gist of the invention described in claim 3 is that a filter used for the division is
3. The multi-pilot tone detection method according to claim 2, wherein a filter matched to the pilot tone signal forming the multi-pilot tone signal is used. The gist of the invention described in claim 4 is that
A multi-pilot tone detection method characterized in that, for a matched filter that detects a multi-pilot tone signal, a filter matched with the multi-pilot tone signal is divided into filters matched with individual pilot tone signals. Exist. The gist of the invention described in claim 5 is that the tap coefficient of a filter used for the division is limited, and the filter is configured without using a multiplier. In the multi-pilot tone detection method. Claim 6
The gist of the present invention is that the multi-pilot tone signal is input to a filter including a number of sub-filters equal to the number of the pilot tone signals constituting the multi-pilot tone signal. 5 is a method for detecting a multi-pilot tone. The gist of the invention described in claim 7 is that the sub-filter is a filter matched to each pilot tone signal, and outputs a correlation between each pilot tone signal and an input waveform. Item 6 is a multi-pilot tone detection method. Claim 8
The gist of the invention described in is that a transfer function of a filter that is set to be equal to the sum of transfer functions of filters matched with the multi-pilot tone signal and matched with each pilot tone constituting the multi-pilot tone signal is added by an adder. By adding to the output signal of the sub-filter,
The method according to claim 7, wherein an output of a filter matched with the multi-pilot tone signal is obtained. According to a ninth aspect of the present invention, the sum of the output signals of the sub-filters matched with the individual pilot tone signals is used as a final filter output. The present invention lies in the described multi-pilot tone detection method. The gist of the invention described in claim 10 is that the number of bits for expressing the tap coefficient is equal to or less than a filter matched to the multi-pilot tone signal. A multi-pilot tone detection method according to one aspect. Claim 11
The gist of the invention described in (1) is a matched filter for detecting a multi-pilot tone signal, wherein a filter matched with the multi-pilot tone signal is divided into filters matched with each pilot tone signal constituting the multi-pilot tone signal. And a matched filter. The gist of the invention according to claim 12 is a matched filter for detecting a multi-pilot tone signal, wherein a filter matched to the multi-pilot tone signal is divided into a plurality of filters. To be a matched filter. Claim 1
The gist of the invention described in claim 3 is that the filter used for the division is configured using a filter matched to the pilot tone signal forming the multi-pilot tone signal. Be in the filter. The gist of the invention described in claim 14 is a matched filter for detecting a multi-pilot tone signal, wherein a filter matched to the multi-pilot tone signal is divided into filters matched to individual pilot tone signals. There is a matched filter characterized by comprising. The gist of the invention described in claim 15 is to limit tap coefficients of a filter used for the division and to configure the filter without using a multiplier. 14. The matched filter according to item 14. The gist of the invention described in claim 16 is that the multi-pilot tone signal is input to a filter including a number of sub-filters equal to the number of the pilot tone signals constituting the multi-pilot tone signal. The matched filter according to claim 15, wherein the matched filter is configured. The gist of the invention according to claim 17 is that the sub-filter is a filter matched to each pilot tone signal,
17. The matched filter according to claim 16, wherein a correlation between each pilot tone signal and an input waveform is output. The gist of the invention according to claim 18 is that the transfer function of the filter set equal to the sum of the transfer functions of the filters matched to the multi-pilot tone signal and matched to each pilot tone constituting the multi-pilot tone signal Is added to an output signal of the sub-filter by an adder to obtain an output of a filter matched with the multi-pilot tone signal.
Above. The gist of the invention described in claim 19 is that the sum of the output signals of the sub-filters matched with the individual pilot tone signals is used as the final filter output. It is in the matched filter described. The gist of the invention described in claim 20 is that the number of bits for expressing the tap coefficient is equal to or less than a filter matched to the multi-pilot tone signal.
20. A matched filter according to any one of 5 to 19 above.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention provides a matched filter for detecting a multi-pilot tone signal, in which a filter matched to a multi-pilot tone signal is divided into filters matched to individual pilot tone signals, thereby reducing the circuit scale. And lower power consumption.

In the present invention, the multi-pilot tone signal is input to a filter composed of a number of sub-filters equal to the number of pilot tone signals constituting the multi-pilot tone signal. The sub-filter is a filter matched to each pilot tone signal, and outputs a correlation between each pilot tone signal and an input waveform. Since the transfer function of the filter matched with the multi-pilot tone signal is equal to the sum of the transfer functions of the filters matched with the pilot tones constituting the multi-pilot tone signal, the adder 4 adds the sub-filter outputs, An output of the filter matched to the pilot tone signal can be obtained.

According to the present invention, the sum of the sub-filter outputs matched to the individual pilot tone signals is used as the final filter output. Therefore, the number of bits for representing the tap coefficients matches the multi-pilot tone signal. Or less. In particular, when the number of pilot tone signals constituting the multi-pilot tone signal is sufficiently large, the number of bits for expressing the tap coefficients of the sub-filter matched to the individual pilot tone signals can be reduced. In particular, ±
When only 2, ± 1,0 is used, a sub-filter can be configured without using a multiplier, and the circuit scale can be reduced. Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a functional block diagram for explaining a matched filter according to an embodiment of the present invention. FIG.
The embodiment shown in FIG. 1 is an example in which the multi-pilot tone detection method is applied to the detection of a preamble using a multi-pilot tone signal arranged at the head of a burst signal.

In the matched filter according to one embodiment of the present invention shown in FIG. 1, the multi-pilot tone signal is composed of sub-filters 1, 2, 3 equal in number to the pilot tone signals constituting the multi-pilot tone signal. Input to the filter. The sub-filters 1, 2, and 3 are filters matched to each pilot tone signal, and output a correlation between each pilot tone signal and an input waveform. Since the transfer function of the filter matched with the multi-pilot tone signal is equal to the sum of the transfer functions of the filters matched with the pilot tones constituting the multi-pilot tone signal, the sub-filters 1, 2, 2,
By adding the three output signals, an output of the filter matched to the multi-pilot tone signal can be obtained.

In the present embodiment, the tap coefficients a0, a1, a2, and t3 are used because the sum of the output signals of the sub-filters 1, 2, and 3 matched to the individual pilot tone signals is used as the final filter output. The number of bits for expressing a3 and a4 can be equal to or smaller than a filter matched to the multi-pilot tone signal. In particular, when the number of pilot tone signals constituting the multi-pilot tone signal is sufficiently large, tap coefficients a0, a1, a of sub-filters 1, 2, and 3 matched to individual pilot tone signals.
The number of bits for expressing 2, a3 and a4 can be reduced. In particular, tap coefficients a0, a1, a2, a
If only ± 2, ± 1,0 are used as 3 and a4, the sub-filters 1, 2, and 3 can be configured without using a multiplier, and the circuit scale can be reduced.

The received signal input to the matched filter for detecting the preamble is a signal of a predetermined frame format, and an example is shown in FIG.
Referring to FIG. 2, in the present embodiment, a preamble composed of a multi-pilot tone signal is arranged at the head of a burst, and data is received following the preamble. The multi-pilot tone signal constituting the preamble is a predetermined signal, and is fixedly arranged at the head of all burst signals.

As shown in FIG. 1, in the present embodiment, the received signal input to the matched filter for multi-pilot tone detection has a number of sub-filters 1 equal to the number n of pilot tones constituting the multi-pilot tone signal. , 2, and 3.

Next, the configuration of the sub-filters 1, 2, 3 will be described with reference to FIG. FIG. 3 is a functional block diagram showing one embodiment of the sub-filters 1, 2, and 3 of FIG. In the present embodiment, a 5-tap FIR filter (Finite Impull) is used as sub-filters 1, 2, and 3.
A case in which a “se Response Filter” (finite impulse response digital filter) is employed will be described.

First, referring to FIG. 3, the input signals of the sub-filters 1, 2, and 3 are sequentially delayed by delay units 5, 6, 7, and 8. Multiplication operation units 9, 10, 11, 12, 13
Are the multiplication operation unit inputs and the multiplication operation units 9, 10, 11, 12,
13. Tap coefficients a0, a1, a2, a set for each of thirteen
3 and a4.

The multiplying operation unit 9 has sub filters 1, 2, 3
Of the sub-filters 1, 2 and 3 delayed by one time slot by the delay unit 5 to the multiplication operation unit 10. The output signal of the delay unit 6 is input to the multiplication operation unit 11, and the sub-filters 1, 2, 2,
3 is input. Similarly, the input signals of the sub-filters 1, 2 and 3 delayed by 3 time slots, which are the output signals of the delay unit 7, are input to the multiplication operation unit 12, and the output of the delay unit 8 is output to the multiplication operation unit 13. The input signals of the sub-filters 1, 2, 3 delayed by 4 time slots are input.

As shown in FIG. 3, tap coefficients a0, a1, a2, and
a3, a4 are set, and the multiplication operators 9, 10, 1
Multiplication operators 9, 10, 11, 1
2, 13 input signals and tap coefficients a0, a1, a2, a
The result of multiplication of 3 and a4 is output. Multiplier 9
Although 0, 11, 12, and 13 can be realized by multipliers, when it is possible to limit the number of bits representing tap coefficients a0, a1, a2, a3, and a4, a configuration that does not use multipliers Can be realized. The adder 14 receives the output signals of the multiplication operators 9, 10, 11, 12, and 13, and outputs the sum of the output signals of the multiplication operators 9, 10, 11, 12, and 13 to the sub-filters 1, 2, and 2. 3 as an output signal.

Returning to FIG. 1, the description will be continued. Output signals of the sub-filters 1, 2, and 3 are input to the adder 4. The adder 4 adds the output signals of the sub-filters 1, 2, and 3, and
The addition result is output as a multi-pilot tone signal matched filter output.

Next, tap coefficients a0, a1, a2, a
The configuration of the sub-filter in the case where 3, a4 is limited to ± 2, ± 1, 0 will be described with reference to a block diagram showing one embodiment of the simplified sub-filter of FIG. FIG.
FIG. 4 is a functional block diagram showing an embodiment of a simplified sub-filter.

Referring to FIG. 4, delay units 15, 16, 1
Reference numerals 7 and 18 'denote delayers for delaying the input signal by one time slot, and sequentially delay the input signals of the sub-filters 1, 2, and 3. The input signals of the sub-filters 1, 2, 3 and the input signals of the sub-filters 1, 2, 3 delayed by the delay units 15, 16, 17, 18 'are multiplied by the multipliers 18, 1
9, 20, 21, and 22.

Next, the configuration of the multiplication units 9, 10, 11, 12, and 13 for realizing -2 times will be described with reference to FIG. FIG. 5 shows the multiplication operation units 9, 10, 11, 1 of FIG.
It is a functional block diagram showing one embodiment of 2 and 13.

Referring to FIG. 5, the sign inverting circuit 24 includes
This is a circuit that performs code conversion of an input signal. When two's complement notation is used as the binary notation, the sign inversion circuit 24 includes, for example, a bit inversion circuit and an adder. The output signal of the sign inverting circuit 24 is input to the bit shift circuit 25 and is shifted by one bit. The multiplication operators 9, 10, 11, 12, 13 for realizing -1 times are, for example,
It is configured by a circuit in which the bit shift circuit 25 is removed from FIG. In addition, multiplication operation units 9 and 1 for realizing the doubling
0, 11, 12, and 13 are configured by, for example, circuits in which the sign inversion circuit 24 is removed from FIG.

Next, the configuration of the multipliers 9, 10, 11, 12, and 13 when the multi-pilot tone signal is a complex number will be described with reference to FIG. FIG. 6 is a functional block diagram showing another embodiment of the multiplication operators 9, 10, 11, 12, and 13 in FIG.

Referring to FIG. 6, a real number multiplication unit 26,
Reference numeral 27 denotes a real number multiplication operation unit shown in FIG. The input real part of the multiplication operation unit is a real number multiplication operation unit 26, 2
8 and the imaginary part of the multiplication operation unit input is input to the real number multiplication operation units 27 and 29. Outputs of the real number multiplication operators 26 and 27 are input to the adder 30, and the addition result is output as a complex multiplication operator output real part. Real number multiplication unit 28,
The output signal of 29 is input to the adder 31, and the addition result is output as the imaginary part of the complex number multiplication operation unit output.

Returning to FIG. 4, the description will be continued. Multiplier 1
The outputs of 8, 19, 20, 21, and 22 are input to an adder 23, and the result of adding the outputs of the multiplication operators 18, 19, 20, 21, and 22 is output as a filter output.

Next, the operation of this embodiment shown in FIG. 1 will be described. First, the filter division in FIG. 1 will be described. Generally, a matched filter is equivalent to a correlation. Pilot tone signals constituting a multi-pilot tone signal (f1 + f2 +... Fn) are denoted by f1, f2,..., Fn, a filter input signal is x, and correlations are f1 (x), f2.
(X), ..., fn (x),

(F1 + f2 + ... + fn) (x) = f1 (x) + f2 (x) + ... + fn (x) Expression (1) is established.

Therefore, as shown in FIG. 1, a filter matched to the multi-pilot tone signal (f1 + f2 +...
.. + Fn)
, Fn, and an adder 4 that adds the output signals of the sub-filters 1, 2, and 3. Here, sub filters 1, 2, 3
Is a multi-pilot tone signal (f1 + f2 +... + F
n) constituting the pilot tone signals f1, f2,.
This is a filter matched to fn.

Next, the sub-filters 1, 2, 3 shown in FIG.
Will be described. As described in the description of the filter division, the multi-pilot tone signal (f1 + f2 +.
The filter matched to fn) can be divided into filters matched to the pilot tone signals f1, f2,..., fn. Each pilot tone signal f1, f2,.
The filter matched to fn provides the pilot tone signal f
, Fn, and a filter that outputs the correlation between the input and the input signal. Therefore, in the case of using a multiplier, the sub-filter is a general one shown in the block diagram of FIG. It is composed of an FIR filter. The tap coefficients a0, a1, a2, a3 of the filter matched to the pilot tone signals f1, f2,..., Fn constituting the multi-pilot tone signal (f1 + f2 +. , A4
Are set, the output signals of the sub-filters 1, 2, 3 become f1 (x), f2 (x),..., Fn (x), and the adder 4 outputs f1 (x) + f2 (x) +. (X)
Is calculated. From equation (1), the output of the adder is equal to the output of the filter matched to the multi-pilot tone signal (f1 + f2 +... + Fn), and a filter matched to the multi-pilot tone signal (f1 + f2 +. You.

Next, the operation of the sub-filter of FIG. 4 will be described. The embodiment shown in FIG. 4 is different from the embodiment shown in FIG. 3 in that multiplication operators 9, 10, 11, 12,.
13 with the simplified multiplication operation units 18 and 1 shown in FIG.
9, 20, 21 and 22. Therefore, if the multiplication operators 18, 19, 20, 21, and 22 realize multiplication of ± 2, ± 1,0 set as the tap coefficients a0, a1, a2, a3, a4, the sub-filter 1, Operate as 2 and 3. Hereinafter, the multiplication unit 1
Operations of 8, 19, 20, 21, and 22 will be described with reference to FIG. When −2 is set as the tap coefficients a0, a1, a2, a3, and a4, the multiplication operators 9, 10, 11, 1
2 and 13 are a sign inversion circuit 24 and a bit shift circuit 2
5. Multiplication of -1 times is performed by the sign inverting circuit 24, and the multiplication operators 18, 19, 20, 21,
The sign of the input signal 22 is inverted. Sign inversion circuit 24
Is input to the bit shift circuit 25, and the output signal of the sign inversion circuit 24 is doubled by the bit shift. From the above, as a whole of the multiplication operation unit, -2 of the input signal is obtained.
It can be seen that doubling is realized. Tap coefficients a0, a1,
When −1 is set as a 2, a 3, and a 4, the multiplication operators 18, 19, 20, 21, and 22 operate as sign inverting circuits 24.
And multiplies the multiplication operation unit input by -1. When 0 is set as the tap coefficients a0, a1, a2, a3, and a4, the multiplication operators 9, 10, 11, 12, and 13 are deleted, and the corresponding input among the inputs of the adder 23 is fixed to 0. Thus, it operates as 0 times. Tap coefficient a0, a
When 1 is set as 1, a2, a3, a4, the multiplication units 9, 10, 11, 12, 13 are deleted, and the outputs of the delay units 15, 16, 17, 18 'are directly input to the adder. By doing so, it operates as one time. Tap coefficient a0, a
When 2 is set as 1, a2, a3, and a4, only the bit shift circuit 25 is provided, so that the entire multiplication operation unit operates as a double multiplication operation unit.

FIGS. 8 to 10 show an operation example of a matched filter of a multi-pilot tone signal (f1 + f2 +... + Fn) using a simplified multiplication operation unit. Also, the multi-pilot tone signal (f1 + f
2+... + Fn) (the number of pilot tones 6) is shown in FIG.
Shown in

FIG. 7 shows a multi-pilot tone signal (f
1 + f2 +... + Fn). FIG. 8 is a graph of a filter output for explaining an operation example of a filter using the multiplication operation unit of FIG. 4 (when there is no quantization error), and FIG. 9 uses the multiplication operation unit of FIG. FIG. 10 is a graph of a filter output (in the case of filter division) for explaining one operation example of the filter.
Graph of filter output for explaining one operation example of the filter using the multiplication operation unit (without filter division)
It is.

The operation examples shown in FIGS. 8 to 10 correspond to the tap coefficients a0, a1, a2, a of the sub-filters 1, 2, and 3.
This is an operation example in the case where 3, a4 is limited to ± 1, 0. As shown in FIG. 8, the filter output (without quantization error) is
This is an ideal filter output when the tap coefficients a0, a1, a2, a3, and a4 are not quantized. As shown in FIG. 9, the filter output (filter division) is a simplified multiplication operation unit. Is the filter output using.

For comparison, as shown in FIG. 10, the tap coefficients a0, a1, a2, a3, and a4 are ± 1,
The filter output when quantization is performed to 0 is shown.

From the above, the pilot tone signals f1, f
In a matched filter configuration that does not use sub-filter division matched to 2,..., Fn, the peak characteristic of the filter output is significantly deteriorated as compared with an ideal filter having no quantization error. The output of the matched filter using the present invention has a peak characteristic almost coincident with the ideal matched filter output, and it can be seen that the circuit scale of the filter can be reduced without affecting the peak characteristic.

As described above, according to the present embodiment, the multi-pilot tone signal (f1 + f2 +... + F
In order to obtain a filter output matched to n), it is possible to use a configuration in which the output signals of the sub-filters 1, 2, 3 matched to the pilot tone signals f1, f2,..., fn are added. This has the effect of realizing scale reduction.

In particular, the multi-pilot tone signal (f1 +
f2 +... + fn)
, Fn, and tap coefficients a0, a1, a of the sub-filters 1, 2, 3 while maintaining the output accuracy.
When it is possible to limit the number of bits expressing 2,2,3, a4, the multiplication operation units (multiplication operation units 9,10,11,12,13, multiplication operation Units 18, 19, 20, 21, 22; real number multiplication operation unit 2
6, 27, 28, 29) can be configured without a multiplier.

It should be noted that the present invention is not limited to the above-described embodiment, and it is apparent that the above-described embodiment can be appropriately modified within the scope of the technical idea of the present invention. Further, the number, position, shape, and the like of the constituent members are not limited to the above-described embodiment, and can be set to numbers, positions, shapes, and the like suitable for carrying out the present invention. In each drawing, the same components are denoted by the same reference numerals.

[0042]

As described above, according to the present invention, in order to obtain a filter output matched with a multi-pilot tone signal, it is possible to use a configuration in which sub-filter outputs matched with each pilot tone signal are added. As a result, there is an effect that the circuit scale can be reduced.

In particular, when there are a plurality of pilot tone signals constituting the multi-pilot tone signal and it is possible to limit the number of bits representing the tap coefficients of the sub-filter while maintaining the output accuracy, the sub-filter is used. Is obtained without using the multiplier.

[Brief description of the drawings]

FIG. 1 is a functional block diagram for explaining a matched filter according to an embodiment of the present invention.

FIG. 2 is an example of a frame format.

FIG. 3 is a functional block diagram showing an embodiment of the sub-filter of FIG.

FIG. 4 is a functional block diagram showing an embodiment of a simplified sub-filter.

FIG. 5 is a functional block diagram illustrating an embodiment of the multiplication operation unit in FIG. 4;

FIG. 6 is a functional block diagram showing another embodiment of the multiplication operation unit in FIG. 4;

FIG. 7 is a graph for explaining an example of a multi-pilot tone signal.

8 is a graph of a filter output (with no quantization error) for explaining an operation example of a filter using the multiplication operation unit of FIG. 4;

9 is a graph (in the case of filter division) of a filter output for describing an operation example of a filter using the multiplication operation unit in FIG. 4;

FIG. 10 is a graph of a filter output for explaining an operation example of a filter using the multiplication operation unit of FIG. 4 (in a case where there is no filter division).

[Explanation of symbols]

 1, 2, 3 ... sub-filter 5, 6, 7, 8 ... delay unit 9, 10, 11, 12, 13 ... multiplication operation unit 4, 14 ... adder 15, 16, 17, 18 '... delay unit 18, 19, 20, 21, 22 Multiplier 23: Adder 24: Sign inverting circuit 25: Bit shift circuit 26, 27, 28, 29 Real multiplyer 30, 30, Adder a0, a1, a2, a3 , A4 ... tap coefficient

Claims (20)

[Claims] 1. A multi-matching filter for detecting a pilot tone signal, wherein a filter matching a multi-pilot tone signal to be detected is replaced with a filter matching each pilot tone signal constituting the multi-pilot tone signal. A multi-pilot tone detection method characterized by being divided and configured. 2. A multi-pilot tone detection apparatus according to claim 1, wherein a filter matched to the multi-pilot tone signal to be detected is divided into a plurality of filters. Method. 3. The multi-pilot tone detection method according to claim 2, wherein a filter matched to the pilot tone signal forming the multi-pilot tone signal is used as a filter used for the division. 4. A matched filter for detecting a multi-pilot tone signal, wherein a filter matched with the multi-pilot tone signal is divided into filters matched with individual pilot tone signals. Pilot tone detection method. 5. The multi-pilot tone detection method according to claim 1, wherein tap coefficients of a filter used for the division are limited, and the filter is configured without using a multiplier. . 6. The multi-pilot tone signal according to claim 5, wherein the multi-pilot tone signal is input to a filter including a number of sub-filters equal to the number of the pilot tone signals constituting the multi-pilot tone signal. Multi-pilot tone detection method. 7. The multi-pilot tone according to claim 6, wherein the sub-filter is a filter matched to each pilot tone signal, and outputs a correlation between each pilot tone signal and an input waveform. Detection method. 8. The sub-filter, wherein a transfer function of a filter installed equal to the sum of transfer functions of filters matched to the multi-pilot tone signal and matched to respective pilot tones constituting the multi-pilot tone signal is added to the sub-filter by an adder. 8. The multi-pilot tone detection method according to claim 7, wherein an output of a filter matched to the multi-pilot tone signal is obtained by adding the output to the multi-pilot tone signal. 9. The multi-pilot tone detection method according to claim 8, wherein an addition result of the output signals of the sub-filter matched to the individual pilot tone signals is used as a final filter output. 10. The multi-pilot tone according to claim 5, wherein the number of bits for expressing the tap coefficient is equal to or smaller than a filter matched to the multi-pilot tone signal. Detection method. 11. A matched filter for detecting a multi-pilot tone signal, wherein the filter matched to the multi-pilot tone signal is divided into filters matched to each pilot tone signal constituting the multi-pilot tone signal. Matched filter characterized by the following. 12. A matched filter for detecting a multi-pilot tone signal, wherein the filter matched to the multi-pilot tone signal is divided into a plurality of filters. 13. The matched filter according to claim 12, wherein the filter used for the division is configured using a filter matched to the pilot tone signal forming the multi-pilot tone signal. 14. A matched filter for detecting a multi-pilot tone signal, wherein a filter matched to the multi-pilot tone signal is divided into filters matched to individual pilot tone signals. filter. 15. The matched filter according to claim 11, wherein tap coefficients of a filter used for the division are limited, and the filter is configured without using a multiplier. 16. The multi-pilot tone signal comprises:
16. The matched filter according to claim 15, wherein the matched filter is configured to be input to a filter including a number of sub-filters equal to the number of the pilot tone signals constituting the multi-pilot tone signal. 17. The apparatus according to claim 16, wherein the sub-filter is a filter matched to each pilot tone signal, and configured to output a correlation between each pilot tone signal and an input waveform. The matched filter according to 1. 18. The sub-filter, wherein an adder adds a transfer function of a filter which is set to be equal to a sum of transfer functions of filters matched to the multi-pilot tone signal and matched to respective pilot tones constituting the multi-pilot tone signal. 18. An output signal of a filter matched to the multi-pilot tone signal is obtained by adding to the output signal of
The matched filter according to 1. 19. The matched filter according to claim 18, wherein the sum of the output signals of the sub-filters matched to the individual pilot tone signals is used as a final filter output. 20. The method according to claim 15, wherein the number of bits for expressing the tap coefficient is equal to or smaller than a filter matched to the multi-pilot tone signal.
The matched filter according to any one of the above.