JPH09326775A - Tdma data receiver - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a TDMA data receiver in which the effect of notch of a reception level due to fading is relaxed and which follows only the reception level fluctuation at a low speed. SOLUTION: The receiver is provided with a measurement means 14 measuring a mean reception level of a reception slot, a normalizing means 15 using a set gain of an AGC amplifier to obtain a mean reception level at an input terminal to the AGC amplifier equivalently, an arithmetic means 16 averaging an output of the normalizing means 15 over a plurality of slots, a multiplier 17 multiplying a set gain of the AGC amplifier by an output of the arithmetic means and an estimate means 26 estimating the AGC amplifier setting gain, and obtains an error signal between an output of a multiplier means and a reference level and multiplies a scaling factor by the error signal to obtain the AGC gain. The effect of the notch is eliminated and the AGC operation in following the low speed reception level fluctuation is attained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a TDMA data receiving device used in digital wireless communication, and more particularly,
The gain setting error of the AGC amplifier is reduced to enable highly accurate reception processing.

[0002]

2. Description of the Related Art A TDMA data receiving apparatus used for mobile communication or the like is provided with an automatic gain control (AGC) circuit so that a received signal level can be kept constant even in the presence of fading. This AGC circuit updates the gain of the received signal in the cycle of the TDMA frame according to the received level and adjusts the received level.

As shown in FIG. 10, a conventional TDMA data receiving apparatus having such a function inputs a received RF signal or a frequency-converted received IF signal according to a received signal input terminal 1 and a gain control code described later. An AGC amplifier 2 for controlling the amplitude of the received signal
The output of the GC amplifier 2 is frequency-converted to output a baseband in-phase component I and a quadrature component Q, and a quadrature detection unit 3 which generates a carrier signal equal to the center frequency of the input reception signal. A local oscillator 7, a phase shifter 6 for shifting the phase of a carrier signal by π / 2, and an AGC amplifier 2
Multipliers 4 and 5 that multiply the output of the carrier signal by the carrier signal or the output signal of the phase shifter 6, and low-pass filters 8 and 9 that remove the double carrier component included in the in-phase and quadrature outputs of the quadrature detector 3. A / D converters 10 and 11 for converting the outputs of the low-pass filters 8 and 9 into digital signals, and A / D converter 1
Baseband demodulation processing unit 12 for demodulating output signals 0 and 11
And the decoded data output terminal 13 for outputting the decoded data which is the output of the baseband demodulation processing unit 12, and the average reception level in the reception slot from the output sample values of the A / D converters 10 and 11 in the reception slot. In-slot reception level measuring section 14, reference level generating section 18 for generating a constant reference level for converging the input signal amplitudes of A / D converters 10, 11 to desired values, and in-slot reception level measurement A subtractor 19 for outputting an error signal obtained by subtracting the output of the reference level generating unit 18 from the output of the unit 14, and a scaling factor generating unit 20 for generating a scaling factor for controlling the amount of change in gain in the AGC amplifier 2. , A multiplier 21 that multiplies the error signal that is the output of the subtractor 19 and the scaling factor that is the output of the scaling factor generating unit 20, and the AGC amp in the current reception slot. And integration unit 22 adds the second gain control signal and the output of the multiplier 21 and updates the value of the gain control signal, an adder constituting the integral operation unit 22
A gain control code generator that converts the output of the delay unit 24 of 23 and one frame, and the integration calculation unit 22 into a gain control code, and uses this code to set the gain of the AGC amplifier 2 in the reception slot after one frame. 25 and.

The AGC amplifier 2 keeps the gain value constant in the reception slot.

FIG. 11 shows a received frame and a corresponding received level. In the reception frame of FIG. 11, it is assumed that RX0 is the reception slot of the own station and the reception slot 40 is currently being received. It is assumed that the AGC amplifier 2 has a gain characteristic shown by the following equation and holds this gain constant in the reception slot.

G (n) = G ₀ · 10 ^{−X (n) / 20} (1) G (n): AGC amplifier gain X (n) in the nth reception slot : Gain control code G ₀ updated every frame period: Unique constant of AGC amplifier Input received signal S (t) to quadrature detection section 3 whose amplitude is controlled by this AGC amplifier 2 is expressed by the following equation. To do.

[0007] S (t) = G (n ) (I (t) cos (2πf c t) + Q (t) sin (2πf c t)) ····· (2) I (t): baseband in-phase component Q (t): a baseband quadrature components f _c: after being frequency-converted into a reception RF frequency or IF frequency above the S (t) baseband through a quadrature detection unit 3, a low-pass filter 8, 9 2
The double carrier component is removed, and the baseband in-phase component G
(N) I (t) and the quadrature component G (n) Q (t) are output. These G (n) I (t) and G (n) Q (t) are A / D
Sample values G (n) I (k
_{T s), G (n)} Q (kT s) (T s: A / D converter 10, 1
1 sampling period). This G (n) I
(KT _s ) and G (n) Q (kT _s ) are input to the baseband demodulation processing unit 12 and demodulated according to a predetermined demodulation method.

On the other hand, G (n) I (kT _s ) and G (n) Q
(KT _s ) is also input to the in-slot reception level measurement unit 14, and the in-slot reception level measurement unit 14 calculates the average reception level R _s (n) in the reception slot 40 shown in FIG. 11 according to the following equation.

R (kT _s ) = (I (kT _s ) ² + Q (kT _s ) ² ) ^1/2 ... (3) (k = 0, 1, 2, ..., M-1) R _s (n) = (1 / M) · G (n) · Σr (kT _s ) (Σ is added from k = 0 to M−1) ··· (4) r (kTs): Instantaneous envelope level M: number of samples in reception slot Note that n in R _s (n) is the value of the nth reception slot. Further, r (kT _s ) in the equation (3) may be calculated as r (kT _s ) = I (kT _s ) ² + Q (kT _s ) ² , and in this case, the reference level described later is also the squared amplitude. Just set it.

Next, the subtractor 19 calculates an error signal e (n) between the R _s (n) and the reference level Ref output from the reference level generator 18.

E (n) = R_s(N) -Ref ···· (5) The value of Ref is input by the AGC amplifier 2.
Signal is amplitude controlled, R _s(N) = Ref (e (n) =
0), the input signals of A / D converters 10 and 11 are
G (n) I (t) and G (n) Q (t) are desired amplitude values
(Maximum amplitude value at which the A / D converter is not saturated)
Is set as follows.

Next, the multiplier 21 outputs the error signal e (n).
Is multiplied by a scaling factor K (K> 0) generated from the scaling factor generating unit 20. Then, the integration calculation unit 22 adds this multiplication result and the gain control signal V (n-1) in the current reception slot to update the value of the control signal, as shown in the following equation.

V (n) = V (n−1) + Ke (n) = V (n−1) + K (R _s (n) −Ref) (6) In the current reception slot The gain control signal of V (n
-1) is described because this value is one frame before (n-1).
This is because it is the value calculated in the (th) receiving slot.

Next, the gain control code generator 25 is shown in FIG.
1 frame (n + 1) th reception slot 41 shown in FIG.
The control code X (n + 1) for setting the gain of the AGC amplifier 2 at is generated. And this code
AGC at a predetermined timing before reception slot 41 of No. 1
Supply to the amplifier 2. Here, for convenience, the following relationships are established.

X (n + 1) = V (n) (7) Therefore, the gain control code of the AGC amplifier 2 is updated according to the following equation from the equations (6) and (7).

X (n + 1) = X (n) + K (R _s (n) -Ref) (8) Further, the gain of the AGC amplifier 2 can be calculated from the following equation (9) from equations (1) and (8). ), And the reception slot 41 (n + 1
The gain G (n + 1) in the (th reception slot) is determined.

G (n + 1) = G (n) · 10 ^{−K (Rs (n) -Ref) / 20} (9) Therefore, from the equation (9), R _s (n) and the reference level Ref
It can be seen that the gain of the AGC amplifier 2 is controlled so that the error between and is small.

As described above, also in the conventional TDMA data receiving apparatus, when the reception levels in the reception slot 40 and the reception slot 41 after one frame are almost the same as the reception level 42 shown in FIG. 11, a highly accurate AGC operation is performed. Can be realized.

[0019]

However, the conventional TDM
In the A data receiving apparatus, as in the reception level 43 shown in FIG. 11, the notch caused by Rayleigh fading hits the receiving slot 40 of the local station, and the notch does not hit in the receiving slot 41 after one frame, When the reception level becomes high, the gain G of the AGC amplifier after one frame determined from the reception level in the reception slot 40
(N + 1) gives an excessive gain to the reception level in the reception slot 41, and the A / D converter 10 and
There was a problem that excessive input would occur for 11.

If the reference level Ref is set to a value smaller than necessary in order to avoid the saturation in the A / D converter due to this excessive input, the quantization error due to the A / D conversion increases during normal operation, There is a problem that the reception sensitivity is deteriorated.

The present invention solves these conventional problems, mitigates the effects of notches in the reception level due to fading, and follows only low-speed reception level fluctuations associated with movement of the receiving device. It is an object of the present invention to provide a TDMA data receiving device capable of performing highly accurate AGC operation.

[0022]

Therefore, the TDM of the present invention.
In the A data receiver, the reception level in the slot is set to AG
By normalizing using the set gain of the C amplifier,
Equivalently, the average reception level in the slot at the input end of the AGC amplifier is obtained, the average reception level in the slot is averaged over a plurality of slots, and based on this average value, the AG
It controls the gain of the C amplifier.

Therefore, it becomes possible to accurately measure the reception level, and through this measurement, the high precision A that follows the fluctuation of the reception level at a low speed in which the influence of the notch is mitigated.
GC operation can be performed.

[0024]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention according to claim 1 of the present invention comprises an AGC amplifier for controlling the amplitude of an input reception signal, measures the reception level of a reception slot addressed to the own station, and In a TDMA data receiving apparatus for setting the gain of an AGC amplifier for a receiving slot addressed to its own station based on the next frame, an in-slot receiving level measuring means for measuring an average receiving level within the receiving slot of a receiving slot addressed to its own station, and an AGC amplifier. The output of the in-slot reception level measuring means is normalized using the set gain of
Gain normalization means for obtaining the average reception level in the slot at the input end of the GC amplifier, and movement of the average reception level in the slot obtained by the gain normalization means from the current reception slot to the reception slot N-1 frames before Between-slot average calculating means for calculating the average, first multiplying means for multiplying the output of the inter-slot average calculating means by the set gain of the AGC amplifier, and an error representing the difference between the output of the first multiplying means and the reference level A subtracting means for outputting a signal, a second multiplying means for multiplying the error signal by a scaling factor for controlling the amount of change in gain in the AGC amplifier, and a control signal for gain setting sent to the AGC amplifier. Based on the gain normalizing means and the gain estimating means for obtaining the set gain of the AGC amplifier to be given to the first multiplying means, AGC on the basis of the output of the multiplication means
The gain of the amplifier is controlled, and the reception level at the input end of the AGC amplifier is equivalently reproduced, and the inter-slot averaging is performed using this. High-accuracy AG that enables measurement of reception level and follows only low-speed reception level fluctuation
C operation can be performed.

According to a second aspect of the present invention, the average reception level in the slot of the current reception slot obtained by the gain normalizing means is divided by the average reception level in the slot one frame before, and the division result is set. If the level difference determination means determines whether the difference is smaller than the threshold value and the level difference determination means determines that the division result is smaller than the threshold value, the average reception level within the slot of the current reception slot obtained by the gain normalization means is calculated. The average reception level in the slot before one frame is output to the average calculation means between slots, and when the determination by the level difference determination means is other than that, the average reception in slot of the current reception slot obtained by the gain normalization means is received. It is provided with an intra-slot reception level replacing means for directly outputting the level to the inter-slot average calculating means. The signal level, for replacing the receiving level of the slot which has not hit the notch performing an average operation between the slots, the influence of the notch is removed, allowing accurate measurement of the reception level.

According to a third aspect of the present invention, the in-slot average reception level of the current reception slot obtained by the gain normalizing means is divided by the in-slot average reception level of one frame before, and the division result is set as a threshold value. Level difference determining means for determining whether or not it is smaller, and scaling factor generating means for switching the value of the scaling factor output to the second multiplying means based on the determination result of the level difference determining means are provided. The value of the scaling factor is set small with respect to the reception level of the slot that hits the notch, and the effect of the notch is mitigated.

According to a fourth aspect of the present invention, the in-slot average reception level of the current reception slot obtained by the gain normalizing means is divided by the in-slot average reception level of one frame before, and the division result is set as a threshold value. Level difference determining means for determining whether or not smaller, if the level difference determining means determines that the division result is smaller than the threshold value, to the average reception level in the slot of the current reception slot obtained by the gain normalizing means, This coefficient is multiplied by a coefficient proportional to the reciprocal of the division result and output to the inter-slot average calculating means, and when the level difference determining means makes any other determination, the gain normalizing means calculates the in-slot average of the current receiving slots. It is provided with a level control means for directly outputting the reception level to the inter-slot average calculation means, so that the reception level of the slot hitting the notch is corrected. The influence of the notch is relaxed.

According to a fifth aspect of the present invention, linear-log conversion means for converting the output of the first multiplication means into a logarithmic value is provided, and the present invention uses AG as a logarithmic value (decibel value).
It can be applied to a control system that controls the gain of a C amplifier.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

(First Embodiment) T of the first embodiment
The DMA data receiving device, as shown in FIG.
A received signal input terminal 1 for inputting a signal or a frequency-converted received IF signal, an AGC amplifier 2 for controlling the amplitude of the input received signal, and an output of the AGC amplifier 2 for frequency conversion to obtain a baseband in-phase component I. , The quadrature detection unit 3 that outputs the quadrature component Q, the local oscillator 7, the π / 2 phase shifter 6 and the multipliers 4 and 5 that constitute the quadrature detection unit 3, and the in-phase and quadrature outputs of the quadrature detection unit 3. Low-pass filters 8 and 9 for removing the doubled carrier component contained therein, A / D converters 10 and 11 for converting the outputs of the low-pass filters 8 and 9 into digital signals, and demodulating the A / D-converted signals A baseband demodulation processing unit 12, a decoded data output terminal 13, and an in-slot reception level measuring unit 14 for measuring an average reception level in a reception slot from output sample values of the A / D converters 10 and 11 in the reception slot. When, The gain normalization that normalizes the output of the in-slot reception level measuring section 14 using the AGC amplifier setting gain obtained by the gain estimating section 26 described later and equivalently obtains the in-slot average reception level at the input end of the AGC amplifier 2 The moving average calculation is performed using the output of the gain normalizing unit 15 and the gain normalizing unit 15 in the receiving slots from the current receiving slot to N-1 frame before, and the calculation result is used as the average receiving level in the current receiving slot. The AG calculated by the inter-slot average calculator 16 and the gain estimator 26 to be output
A multiplier 17 for multiplying the output of the inter-slot averaging unit 16 by the C amplifier setting gain, and a reference for generating a constant reference level for converging the input signal amplitudes of the A / D converters 10 and 11 to desired values. Level generator 18 and a subtracter that subtracts the output of the reference level generator 18 from the output of the multiplier 17 to obtain an error signal
19, a scaling factor generator 20 for generating a scaling factor for controlling the amount of gain change in the AGC amplifier 2, an error signal output from the subtractor 19 and a scaling factor output from the scaling factor generator 20. And a multiplication unit 21, an integration calculation unit 22 that adds the gain control signal of the AGC amplifier 2 in the current reception slot and the output of the multiplication unit 21 to update the value of the gain control signal, and this integration calculation. The output of the adder 23 and the 1-frame delay unit 24, which constitute the unit 22, and the integration calculation unit 22 is converted into a gain control code, and this gain control code is used to output the AGC amplifier 2 in the reception slot one frame later. A gain control code generator 25 for setting a gain and a gain estimator 26 for obtaining a set gain of the AGC amplifier 2 one frame later from the output of the integral calculator 22 are provided. I have.

As shown in FIG. 9, the gain estimating section 26 is a constant generating section for generating a weighting constant (-1/20).
27, a multiplier 28 that multiplies the output of the integration calculation unit 22 by a weighting constant, a log-linear conversion unit 29 that performs log-linear conversion of the output of the multiplier 28, and the output of the log-linear conversion unit 29 is multiplied by a unique constant. The gain adjusting unit 44 for obtaining the set gain of the AGC amplifier 2 and the 1-frame delay unit 30 for delaying the output of the gain adjusting unit 44 by 1 frame are provided.

Next, the operation of this receiving apparatus will be described.

Now, in the reception frame of FIG. 11, R
XO is the receiving slot of the own station, and currently receiving slot 40
Suppose you are receiving.

Like the conventional device, the AGC amplifier 2 has a gain characteristic expressed by the following equation and holds this gain constant in the receiving slot.

G (n) = G ₀ · 10 ^{−X (n) / 20} (1) G (n): AGC amplifier gain X (n) in the nth reception slot : Gain control code updated every frame period G ₀ : Inherent constant of AGC amplifier The input reception signal S (t) to the quadrature detection unit 3 whose amplitude is controlled by this AGC amplifier 2 is expressed by the following equation. And

[0036] S (t) = G (n ) (I (t) cos (2πf c t) + Q (t) sin (2πf c t)) ····· (2) I (t): baseband in-phase component Q (t): a baseband quadrature components f _c: after being frequency-converted into a reception RF frequency or IF frequency above the S (t) baseband through a quadrature detection unit 3, a low-pass filter 8, 9 2
The double carrier component is removed, and the baseband in-phase component G
(N) I (t) and the quadrature component G (n) Q (t) are output.

Next, this G (n) I (t), G (n)
Q (t) is the sample value sequence G (n) in the A / D converters 10 and 11.
I (kT _s ), G (n) Q (kT _s ) (T _s : sampling period of A / D converters 10 and 11). This G
(N) I (kT _s ) and G (n) Q (kT _s ) are input to the baseband demodulation processing unit 12 and demodulated according to a predetermined demodulation method.

On the other hand, G (n) I (kT _s ) and G (n) Q
(KT _s ) is also input to the in-slot reception level measuring unit 14, and the in-slot reception level measuring unit 14 receives the average reception level R _s (in the reception slot 40 shown in FIG. 11 as in the conventional device. n) is calculated according to the following formula.

R (kT _s ) = (I (kT _s ) ² + Q (kT _s ) ² ) ^1/2 ... (3) (k = 0, 1, 2, ..., M-1) R _s (n) = (1 / M) · G (n) · Σr (kT _s ) ··· (4) (Σ is added from k = 0 to M−1) r (kT _s ): Instantaneous envelope Line level M: number of samples in reception slot Note that n in R _s (n) is the value of the nth reception slot. Further, r (kT _s ) in the equation (3) may be calculated as r (kT _s ) = (I (kT _s ) ² + Q (kT _s ) ² ), and in this case, the reference level described later is also squared. It may be set as the amplitude.

Next, the gain normalization unit 15 normalizes R _s (n) using the AGC amplifier setting gain G (n) obtained from the gain estimation unit 26, as shown in the following equation.

R (n) = R _s (n) / G (n) = (1 / M) · Σr (kT _s ) ... (10) (Σ is added from k = 0 to M−1) R (n) normalized by (10) is the AGC amplifier 2
This corresponds to the average reception level in the slot at the input end of.

Next, the inter-slot averaging unit 16 uses R (n) from the current reception slot to the reception slot N-1 frames before to perform a moving average calculation as shown in the following equation. The calculation result is output as the average reception level of the current reception slot.

R _ave (n) = (1 / N) · ΣR (n−k) ···· (11) (Σ is added from k = 0 to N−1) N: Moving average calculation Number of reception slots to perform (N ≧ 1) Next, the multiplier 17 calculates the gain estimation unit 26 as shown in the following equation.
AGC amplifier setting gain G (n) obtained from
_ave (n) is multiplied and R _x (n) is output.

R _x (n) = G (n) R _ave (n) (12) Next, the subtractor 19 outputs R _x (n) and the reference level generator 16. Error signal e between the reference level Ref
(N) is calculated by the following formula.

E (n) = R _x (n) −Ref (13) Note that the value of Ref is such that R _x (n) = Ref when the input reception signal is amplitude controlled by the AGC amplifier 2. (E (n) =
0), the input signals G (n) I (t) and G (n) Q (t) of the A / D converters 10 and 11 have desired amplitude values (when the A / D converter is saturated). It is set so that the maximum amplitude value) is not reached.

Next, the multiplier 21 outputs the error signal e (n).
Is multiplied by a scaling factor K (K> 0) generated from the scaling factor generating unit 20. Then, as shown in the following equation, the integral calculation unit 22 adds this multiplication result to the gain control signal V (n-1) in the current reception slot and updates the value of the control signal.

V (n) = V (n−1) + Ke (n) = V (n−1) + K (R _x (n) −Ref) (14) In the current reception slot, The gain control signal is V (n
-1) is described because this value is one frame before (n-1).
This is because the value is calculated based on the (th) reception slot.

Next, the gain control code generator 25 operates as shown in FIG.
1 frame (n + 1) th reception slot 41 shown in FIG.
The control code X (n + 1) for setting the gain of the AGC amplifier 2 at is generated. Then, this code is sent to the AGC amplifier 2 at a predetermined timing before the reception slot 41
To supply. Note that here, for convenience, the following relationships are established.

X (n + 1) = V (n) (7) Therefore, the gain control code of the AGC amplifier 2 is updated according to the following equation from the equations (14) and (7).

X (n + 1) = X (n) + K (R _x (n) -Ref) (15) Further, from the equations (1) and (15), the gain of the AGC amplifier 2 is expressed by the following equation. To the gain G (n + 1) of the reception slot 41 (n + 1th reception slot).

G (n + 1) = G (n) · 10 ^{−K (Rx (n) -Ref) / 20} (16) Therefore, from the equation (16), R _x (n) and the reference level Re
It can be seen that the gain of the AGC amplifier 2 is controlled so that the error with f is reduced.

On the other hand, in the gain estimation unit 26, the multiplier 28
The output V (n) = X (n + 1) of the integral calculation unit 22 is multiplied by the weighting constant (-1/20) generated from the constant generation unit 27, and the result is displayed by the log-linear conversion unit 29. Log-linear conversion is performed as shown in the equation.

Z (n + 1) = 10 ^{−X (n + 1) / 20} (17) Next, the gain adjusting unit 44 sets this value to the characteristic constant G of the AGC amplifier as shown in the following equation. Multiply by ₀ and AGC amplifier 2
Get the set gain of.

[0054] setting a gain indicated in G (n + 1) = G 0 · Z (n + 1) = G 0 · 10 -X (n + 1) / 20 ·· (18) Equation (18), a one-frame delay circuit 30 It is supplied to the gain normalization unit 15 and the multiplier 17 via the.

As described above, in the TDMA data receiving apparatus of the first embodiment, the reception level at the input end of the AGC amplifier 2 is reproduced equivalently, the inter-slot average calculation is performed using this reception level, and the calculation result is obtained. Is used to find the gain of the AGC amplifier 2 in the next frame. Therefore, even if the notch of the reception level due to Rayleigh fading hits the reception slot 40 of the local station and the reception level becomes high in the reception slot 41 after one frame like the reception level 43 shown in FIG. Can be mitigated, and high-accuracy AGC operation can be performed that follows only fluctuations in the reception level at low speed.

(Second Embodiment) T of the second embodiment
The DMA data receiving device is adapted to a control system for performing gain control of the AGC amplifier with a logarithmic value, and as shown in FIG. 2, converts the output of the multiplier 17 into a logarithmic value (decibel value). A linear-log conversion unit 31 is provided. Other configurations are the same as those of the first embodiment (FIG. 1).

In this device, the AGC amplifier 2 has the following equation (1
It has the gain characteristic shown in 9) and keeps this gain constant in the receiving slot. G (n) = G ₀ · 10 ^{−XL (n) / 20} ··· (19) G (n): AGC amplifier gain in the nth reception slot XL (n): every frame period Gain control code updated to G ₀ : Unique constant of AGC amplifier.

The input reception signal S (t) to the quadrature detector 3 whose amplitude is controlled by the AGC amplifier 2 is expressed by the following equation.

[0059] S (t) = G (n ) (I (t) cos (2πf c t) + Q (t) sin (2πf c t)) ····· (2) I (t): baseband in-phase component Q (t): a baseband quadrature components f _c: reception RF frequency or the IF frequency the signal S (t), the quadrature detection unit 3, A / D converters 10 and 11, the slot in the reception level measuring unit 14 The gain normalizer 15, the inter-slot average calculator 16 and the multiplier 17 are
The same operation as that of the above embodiment is performed. That is, the in-slot reception level measuring unit 14 uses the above equations (3) and (4)
The average reception level R _s (n) in the reception slot 40 is calculated, and the gain normalization unit 15 calculates R R according to the equation (10).
_s (n) is normalized with the AGC amplifier setting gain G (n) obtained from the gain estimation unit 26 to obtain R (n), and the inter-slot average calculation unit 16 calculates from the current reception slot according to equation (11). R up to the reception slot N-1 frames before
The moving average R _ave (n) of (n) is calculated, and the multiplier 1
7 calculates R _x (n) by multiplying R _ave (n) by the AGC amplifier setting gain G (n) obtained from the gain estimating unit 26, as shown in Expression (12).

Next, the linear-to-log converter 31 uses this R _x.
(N) is converted into a logarithmic value (decibel value) as shown in the following equation.

L _x (n) = 20 log ₁₀ (R _x (n)) (20) Next, the subtracter 19 outputs the L _x (n) and the reference level generator 32 from the reference level generator 32. The error signal e (n) between the output reference level Ref and the logarithmic value is calculated by the following equation (21).

[0062] _{e (n) = L x (} n) -20log 10 (Ref) = 20log 10 (R x (n) / Ref) ···· (21) Note that the value of Ref, like the conventional apparatus , AGC amplifier 2 controls the amplitude of the input reception signal, and R _x (n) = R
When ef (e (n) = 0), A / D converter 10,
11 input signals G (n) I (t), G (n) Q
(T) is set to a desired amplitude value (maximum amplitude value at which the A / D converter is not saturated).

Next, the multiplier 21 outputs the error signal e (n).
Is multiplied by a scaling factor K (K> 0). The integral calculation unit 22 adds the multiplication result and the gain control signal VL (n-1) at the current reception slot, as shown in the following equation, and updates the value of the control signal.

VL (n) = VL (n−1) + Ke (n) = VL (n−1) + 20log ₁₀ (R _x (n) / Ref) ^K (22) Note that the current reception slot Gain control signal at VL
(N-1) is described because this value is one frame before (n
This is because it is the value calculated in the (-1st) receiving slot.

Next, the gain control code generator 33 is shown in FIG.
1 frame (n + 1) th reception slot 41 shown in FIG.
The control code XL (n + 1) for setting the gain of the AGC amplifier 2 is generated. Then, this code is supplied to the AGC amplifier 2 at a predetermined timing before the reception slot 41. Here, for convenience, the following relationships are established.

XL (n + 1) = VL (n) (23) Therefore, from the expressions (22) and (23), the gain control code of the AGC amplifier 2 is updated by the following expression.

XL (n + 1) = XL (n) + 20log ₁₀ (R _x (n) / Ref) ^K (24) Further, from the equations (19) and (24), the gain of the AGC amplifier 2 is calculated by the following equation. And the gain G (n + 1) in the reception slot 41 (n + 1th reception slot) is determined.

G (n + 1) = G (n) (Ref / R _x (n)) ^K (25) Therefore, from the equation (25), R _x (n) is the reference level Re.
It can be seen that the gain of the AGC amplifier 2 is controlled so as to approach the value of f.

On the other hand, the gain estimating unit 26 having the configuration of FIG.
Then, the multiplier 28 outputs the output VL (n) = X of the integration calculation unit 22.
-1/2 generated by the constant generator 27 in L (n + 1)
The weighting constant of 0 is multiplied, and the result is log-linear converted by the log-linear conversion unit 29 as shown in the following equation.

Z (n + 1) = 10 ^{−XL (n + 1) / 20} (17) Next, the gain adjusting unit 44 sets this value to the intrinsic constant G of the AGC amplifier as shown in the following equation. Multiply by ₀ and AGC amplifier 2
Get the set gain of.

[0071] setting a gain indicated in G (n + 1) = G 0 · Z (n + 1) = G 0 · 10 -XL (n + 1) / 20 ·· (18) Equation (18), a one-frame delay circuit 30 It is supplied to the gain normalization unit 15 and the multiplier 17 via the.

As described above, in the TDMA data receiving apparatus of the second embodiment, the reception level at the input end of the AGC amplifier 2 is reproduced equivalently, and the inter-slot average calculation is performed using this reception level. Is used to calculate the gain of the AGC amplifier 2 in the next frame, and at the same time, the gain is converted into a logarithmic value (decibel value). Therefore, this embodiment is applied to a device in which the gain control of the AGC amplifier is performed logarithmically, so that the effect of the notch is mitigated and a highly accurate AGC operation that follows only the low-speed fluctuation of the reception level is performed. Is possible.

(Third Embodiment) T of the third embodiment
When the receiving slot hits the notch, the DMA data receiving device uses the average receiving level in the slot of the receiving slot that did not hit the notch instead as the average receiving level in the slot.

As shown in FIG. 3, this receiving apparatus divides the normalized average reception level in the slot in the current reception slot by the normalized average reception level in the slot one frame before, and the result is When the level difference determination unit 34 determines whether the difference is smaller than the threshold value and the level difference determination unit 34 is smaller than the threshold value, the normalized average reception level in the slot in the current reception slot is set to the slot one frame before. An in-slot reception level replacing unit 35 for replacing the inner average reception level is provided. Other configurations are the same as those of the first embodiment (FIG. 1).

In this receiving apparatus, as in the first embodiment, the in-slot reception level measuring unit 14 uses the equations (3) and (4).
Then, the average reception level R _s (n) in the reception slot 40 shown in FIG. 11 is calculated, and the gain normalization unit 15 calculates
0), R _s (n) is set to AGC amplifier setting gain G
Normalize with (n). The normalized value R (n) corresponds to the average reception level in the slot at the input end of the AGC amplifier 2.

Next, the level difference determination unit 34 uses the following equation (26).
, The gain-normalized in-slot average reception level R (n) in the current reception slot is converted to the gain-normalized in-slot average reception level R (n-
The division is performed in 1), and it is determined whether the division result D is smaller than the set threshold value Vth.

D = R (n) / R (n−1) (26) The in-slot reception level replacing unit 35 includes the level difference determining unit 34.
However, when it is determined that the division result D is smaller than the threshold Vth, it is determined that the average reception level in the slot in the current reception slot has decreased due to the notch of the reception level due to fading, and The normalized in-slot average reception level R (n) is replaced with the normalized in-slot average reception level R (n-1) one frame before. That is, the output R _c (n) of the in-slot reception level replacing unit 35 is as follows.

D ≧ Vth: R _c (n) = R (n) (27a) D <Vth: R _c (n) = R (n−1) (27b) Slot The inter-average calculation unit 36 uses the outputs from the current reception slot output from the intra-slot reception level replacement unit 35 to the reception slot N-1 frames before to perform the moving average calculation according to the following equation, and the calculation result Is output as the average reception level in the current reception slot.

R _cave (n) = (1 / N) · ΣR (n−k) ···· (28) (Σ is added from k = 0 to N−1) N: Moving average calculation Number of reception slots (N ≧ 1) to be performed Subsequent operations of the multiplier 17, the subtractor 19, the multiplier 21, the integration calculator 22, and the gain control code generator 25 are substantially the same as those in the first embodiment. In addition, the operation of the gain estimating unit 26 is also the same as that of the first embodiment.

In the TDMA receiver according to the third embodiment, the notch of the receiving level hits the receiving slot 40 of the own station as shown by the receiving level 43 of FIG. Even if the level becomes high, the level difference determination unit 34 detects this notch by using the reception level of the input terminal of the AGC amplifier reproduced equivalently,
The average reception level of the reception slot that hit the notch is 1
Since it is replaced with the average reception level of the slot before the frame, the effect of the notch is removed. In addition, since the inter-slot average is calculated using the average reception level in the slot after performing such processing, the influence of past gain setting errors in this calculation is mitigated, and accurate reception level measurement becomes possible. It is possible to perform a high-accuracy AGC operation that follows only the fluctuation at low speed.

(Fourth Embodiment) T of the fourth embodiment
The DMA data receiving device is a device in which the configuration of the third embodiment can be applied to a receiving device that controls the gain of an AGC amplifier with a logarithmic value, and as shown in FIG. The linear-log conversion unit 31 is provided for converting the output of the multiplier 17 that multiplies the AGC amplifier set gain into a logarithmic value (decibel value). Other configurations are
There is no difference from the third embodiment (FIG. 3).

In this receiver, the AGC amplifier 2 has a gain characteristic of G (n) = G ₀ ^{-10 −XL (n) / 20} (19) as in the second embodiment. To have.

The intra-slot reception level replacing unit 35, the inter-slot average calculating unit 36, and the multiplier 17 perform the same operations as in the third embodiment, and the intra-slot reception level replacing unit 35.
When R _c (n) is output by the above equations (27a) and (27b), the inter-slot averaging unit 36 outputs the moving average result R _cave (n) by the above equation (28), and the multiplier 17
This is multiplied by the AGC amplifier setting gain G (n) output from the gain estimation unit 26, and R _cx (n) = G (n) R _cave (n) ... (29) is output.

The linear-to-log converter 31 converts the output R _cx (n) of the multiplier 17 into a logarithmic value (decibel value) as shown in the following equation.

L _x (n) = 20 log ₁₀ (R _cx (n)) (34) Subsequent to the linear-log conversion unit 31, the subtracter 19 and the multiplier 2
The operations of 1, the integration calculator 22, the gain control code generator 33, and the gain estimator 26 are substantially the same as those in the second embodiment in which the gain control of the AGC amplifier is performed logarithmically.

As described above, the fourth embodiment is applied to a receiving apparatus that controls the gain of an AGC amplifier with a logarithmic value (decibel value) to eliminate the influence of notches and reduce only the fluctuation of the receiving level at low speed. Enables highly accurate AGC operation to follow.

(Fifth Embodiment) T of the fifth embodiment
The DMA data receiving apparatus reduces the effect of the notch by switching the scaling factor to a small value when the notch hits the receiving slot.

As shown in FIG. 5, this receiving apparatus divides the normalized reception average slot level in the current reception slot by the normalized reception slot average reception level one frame before, and the result is less than the threshold value. A level difference determination unit 34 for determining whether or not it is small and two different scaling factors as values for controlling the gain change amount of the AGC amplifier 2 are provided, and according to the determination result of the level difference determination unit 34,
And a scaling factor generator 37 for selecting the value of the scaling factor to be output. Other configurations are the same as those of the first embodiment (FIG. 1).

The scaling factor generating unit 37 selects a scaling factor having a small value when the level difference determining unit 34 determines that the notch of the reception level has been hit, and selects a scaling factor having a large value otherwise. To do.

In this receiving apparatus, the in-slot reception level measuring section 14, the gain normalizing section 15, the inter-slot averaging section 1
6, the multiplier 17, the reference level generator 18, and the subtractor 19 perform the same operation as in the first embodiment, and the subtractor 19 uses the equation (1
According to 3), the error signal e (n) is output.

E (n) = R _x (n) −Ref (13) On the other hand, the level difference determination unit 34 determines the gain normal in the current reception slot as shown in the following equation (26). The output R (n) of the normalization unit 15 is the output R of the gain normalization unit 15 one frame before.
The threshold value Vth in which the division result D is set by dividing by (n-1)
It is determined whether it is smaller than.

D = R _s (n) / R _s (n−1) (26) The level difference determination unit 34 notifies the scaling factor generation unit 37 of the determination result. The scaling factor generator 37 uses two different scaling factors K as values for controlling the amount of gain change in the AGC amplifier 2.
1 and K2 (K1, K2> 0, K1 <K2), and when the determination result of the level difference determination unit 34 is D <Vth, it is determined that the notch of the reception level due to fading is hit, and it is small. A value scaling factor K1 is selected, and when D ≧ Vth, a large value scaling factor K2 is selected and output.

The multiplier 21 multiplies the error signal e (n) by the scaling factor Ki (i = 1 or 2) output from the scaling factor generator 37, and the integral calculator 22
Is obtained by adding the multiplication result and the gain control signal V (n-1) at the current reception slot, and using the following equation (39),
Update the value of the control signal.

V (n) = V (n−1) + Kie (n) = V (n−1) + Ki (R _x (n) −Ref) (39) The gain control code generator 25 Control code X (n + 1)
Is updated according to the following formula.

X (n + 1) = X (n) + Ki (R _x (n) -Ref) (40) Further, the gain of the AGC amplifier 2 is updated as in the following equation, and the reception slot 41 (n + 1) is updated. The gain G (n + 1) in the (th reception slot) is determined.

G (n + 1) = G (n) · 10 ^{−Ki (Rx (n) -Ref) / 20} (41) Therefore, from the equation (41), R _x (n) and the reference level Re
It can be seen that the gain of the AGC amplifier 2 is controlled so that the error with f is reduced. Further, from the equation, the amount of change in gain can be controlled by switching the value of the scaling factor Ki. Therefore, even if a notch of the reception level occurs, switching of Ki to a small value suppresses an excessive increase in gain. You can see that you can.

As described above, the TDMA data receiving apparatus according to the fifth embodiment has the same level as the reception level 43 shown in FIG.
Even if the reception level notch due to Rayleigh fading hits the reception slot 40 of the own station and the reception level becomes high in the reception slot 41 after one frame, the reception level at the input end of the AGC amplifier is reproduced equivalently. This notch is detected by the level difference determination unit 34 by using, and the value of the scaling factor that controls the gain change amount of the AGC amplifier is switched, thereby alleviating the effect of the notch and reducing the reception level at low speeds. A highly accurate AGC operation that follows only fluctuations can be performed.

(Sixth Embodiment) T of the sixth embodiment
The DMA data receiving device is a device in which the configuration of the fifth embodiment can be applied to a receiving device that controls the gain of an AGC amplifier with a logarithmic value, and as shown in FIG. The linear-log conversion unit 31 is provided for converting the output of the multiplier 17 that multiplies the AGC amplifier set gain into a logarithmic value (decibel value). Other configurations are
There is no difference from the fifth embodiment (FIG. 5).

In this receiver, the linear-log conversion unit 31 uses the output R _{x of the} multiplier 17 as in the second embodiment having a control system for controlling the gain of the AGC amplifier by logarithmic values.
(N) is converted into a logarithmic value (decibel value) as shown in the following equation.

L _x (n) = 20 log ₁₀ (R _x (n)) (20) Level difference determination section 34 and scaling factor generation section 37
Performs the same operation as in the fifth embodiment, and follows the linear-log conversion unit 31, the subtractor 19, the multiplier 21, the integration calculator 22, the gain control code generation unit 33, and the gain estimation unit 26.
Performs substantially the same operation as the second embodiment in which the gain control of the AGC amplifier is logarithmically performed.

As described above, the sixth embodiment is applied to a receiver that controls the gain of an AGC amplifier with a logarithmic value (decibel value) to switch the value of the scaling factor, as in the fifth embodiment. The operation of reducing the influence of the notch can be performed.

(Seventh Embodiment) T of the seventh embodiment
When the notch hits the receiving slot, the DMA data receiving apparatus corrects the receiving level of the slot to reduce the influence of the notch.

As shown in FIG. 7, this receiving device divides the normalized reception average slot level in the current reception slot by the normalized reception slot average reception level one frame before, and the division result is less than the threshold value. When the level difference determination unit 34 that determines whether the difference is smaller and the level difference determination unit 34 determines that it is smaller than the threshold value, a level that multiplies the output of the gain normalization unit 15 by a coefficient proportional to the reciprocal of the division result. Control unit
39 and. Other configurations are the same as those of the first embodiment (FIG. 1).

The in-slot reception level measuring unit 14 and the gain normalizing unit 15 of this receiving device perform the same operation as in the first embodiment, and the gain normalizing unit 15 uses the AGC amplifier 2 according to the following equation (10). R (n) corresponding to the average reception level in the slot at the input terminal of is output.

R (n) = R _s (n) / G (n) = (1 / M) · Σr (kT _s ) (Σ is added from k = 0 to N−1) (10) Next Then, the level difference determination unit 34 calculates the gain-normalized in-slot average reception level R (n) in the current reception slot by one frame before the gain-normalized in-slot average reception level R as shown in the following equation. It divides by (n-1) and determines whether the division result D is smaller than the set threshold value Vth.

D = R (n) / R (n−1) (26) When the level difference determination unit 34 determines that the division result D is smaller than the threshold value Vth, the level control unit 39 Is determined to have decreased the average reception level in the slot in the current reception slot due to the notch of the reception level due to fading, and is proportional to the reciprocal of D obtained by the equation (26) with respect to R (n). Multiply the coefficients. That is, the output R _LC (n) of the level control unit 39 is as follows.

D ≧ Vth: R _LC (n) = R (n) (45a) D <Vth: R _LC (n) = Lev · R (n) (45b) Lev = A / D (46) A: Proportional constant Next, the inter-slot averaging unit 38 calculates the output of the level control unit 39 in the reception slot from the current reception slot to N-1 frames before. Then, a moving average calculation as shown in the following equation is performed, and the calculation result is output as the average reception level in the current reception slot.

R _Lave (n) = (1 / N) · ΣR _LC (n−k) (47) (Σ is added from k = 0 to N−1) N: Moving average calculation Number of reception slots to perform (N ≧ 1) Multiplier 17, subtractor 19, multiplier 21, integration calculator 22, gain control code generator 25, and gain estimator 26 that follow.
Performs the same operation as in the first embodiment.

As described above, the TDMA data receiving apparatus according to the seventh embodiment has the same structure as the reception level 43 shown in FIG.
Even if the reception level notch due to Rayleigh fading hits the reception slot 40 of the own station and the reception level becomes high in the reception slot 41 after one frame, the reception level at the input end of the AGC amplifier is reproduced equivalently. The notch effect is mitigated by detecting this notch in the level difference determination unit 34 using, and correcting the reception level of the slot when the notch is detected. Therefore, a highly accurate AGC that follows only low-speed fluctuations in the reception level
Can perform actions.

(Eighth Embodiment) T of the eighth embodiment
The DMA data receiving device is a device in which the configuration of the seventh embodiment can be applied to a receiving device that performs gain control of an AGC amplifier with a logarithmic value, and as shown in FIG. The linear-log conversion unit 31 is provided for converting the output of the multiplier 17 that multiplies the AGC amplifier set gain into a logarithmic value (decibel value). Other configurations are the same as those of the seventh embodiment (FIG. 7).

In this receiver, the linear-log conversion unit 31 uses the output R _{cy of the} multiplier 17 as in the second embodiment having a control system for controlling the gain of the AGC amplifier by logarithmic values.
(N) is converted into a logarithmic value (decibel value) as shown in the following equation.

L _y (n) = 20 log ₁₀ (R _cy (n)) (53) The level difference determination unit 34, the level control unit 39, and the inter-slot average calculation unit 38 are The same operation as that of the embodiment of the present invention, and subsequent to the linear-log conversion unit 31, the subtractor 19, the multiplier 21, the integration calculator 22, the gain control code generation unit 33, and the gain estimation unit 26 are logarithmic values. The operation is substantially the same as that of the second embodiment for controlling the gain of the AGC amplifier.

As described above, the eighth embodiment is applied to a receiver that controls the gain of an AGC amplifier with a logarithmic value (decibel value), and the slot in which the notch is detected is the same as in the seventh embodiment. By correcting the reception level of, it is possible to perform the operation of reducing the influence of the notch.

[0114]

As is apparent from the above description, the TDMA data receiving apparatus of the present invention is provided with the gain normalizing section, and the average reception level in the slot measured in the base band is normalized by the set gain of the AGC amplifier. By doing so, the in-slot reception level at the input end of the AGC amplifier is equivalently obtained, and the moving average calculation between slots is performed using this value to calculate the average reception level.

Therefore, even when the reception slot of the local station collides with the reception level notch due to Rayleigh fading, the effect of the gain setting error due to this notch is reduced, and more accurate reception level measurement becomes possible and low speed It is possible to perform a highly accurate AGC operation that follows the fluctuation of the reception level.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a TDMA data receiving device according to a first embodiment of the present invention,

FIG. 2 is a configuration diagram of a TDMA data receiving device according to a second embodiment of the present invention,

FIG. 3 is a configuration diagram of a TDMA data receiving device according to a third embodiment of the present invention,

FIG. 4 is a configuration diagram of a TDMA data receiving device according to a fourth embodiment of the present invention,

FIG. 5 is a configuration diagram of a TDMA data receiving device according to a fifth embodiment of the present invention,

FIG. 6 is a configuration diagram of a TDMA data receiving device according to a sixth embodiment of the present invention,

FIG. 7 is a configuration diagram of a TDMA data receiving device according to a seventh embodiment of the present invention,

FIG. 8 is a configuration diagram of a TDMA data receiving device according to an eighth embodiment of the present invention,

FIG. 9 is a configuration diagram of a gain estimation unit in each embodiment of the present invention,

FIG. 10 is a configuration diagram of a conventional TDMA data receiving device,

FIG. 11 is a diagram showing received frames and corresponding received levels.

[Explanation of symbols]

 1 Received signal input terminal 2 AGC amplifier 3 Quadrature detector 4, 5, 17, 21, 28 Multiplier 6 π / 2 Phase shifter 7 Local oscillator 8, 9 Low-pass filter 10, 11 A / D converter 12 Baseband demodulation Processing unit 13 Decoded data output terminal 14 In-slot reception level measurement unit 15 Gain normalization unit 16, 36, 38 Inter-slot average calculation unit 18, 32 Reference level generation unit 19 Subtractor 20, 37 Scaling factor generation unit 22 Integration calculation unit 23 Adder 24, 30 1-frame delay device 25, 33 Gain control code generator 26 Gain estimator 27 Constant generator 29 Log-linear converter 31 Linear-log converter 34 Level difference judgment unit 35 In-slot reception level replacement unit 39 Level control block 40, 41 Self-pole receive slot 42, 43 Receive level 44 Gain adjuster

Claims (5)

[Claims] 1. An AG for controlling the amplitude of a received signal to be input.
A TDMA data receiving apparatus, which comprises a C amplifier, measures the reception level of a reception slot addressed to the own station, and sets the gain of the AGC amplifier for the reception slot addressed to the own station of the next frame based on the measurement result. In-slot reception level measuring means for measuring the average reception level in the reception slot of the destination reception slot, and the output of the in-slot reception level measuring means is normalized using the set gain of the AGC amplifier, and equivalently to the A
A gain normalizing means for obtaining an average reception level in a slot at the input end of the GC amplifier, and the gain normalizing means calculates N-1 from the current reception slot.
Inter-slot averaging means for computing a moving average of the in-slot average reception level obtained up to the reception slot before the frame, and first multiplication means for multiplying the output of the inter-slot average computing means by the set gain of the AGC amplifier. And subtraction means for outputting an error signal representing the difference between the output of the first multiplication means and a reference level, and the error signal multiplied by a scaling factor for controlling the amount of gain change in the AGC amplifier. Second
And a gain estimating means for obtaining a set gain of the AGC amplifier to be given to the gain normalizing means and the first multiplying means, based on a gain setting control signal sent to the AGC amplifier. A TDMA data receiving apparatus, wherein the gain of the AGC amplifier is controlled based on the output of the second multiplication means. 2. The in-slot average reception level of the current reception slot obtained by the gain normalizing means is divided by the in-slot average reception level of one frame before, and it is determined whether or not the division result is smaller than a set threshold value. When the level difference determination means and the level difference determination means determine that the division result is smaller than the threshold value, the average slot reception level of the current reception slot obtained by the gain normalization means is 1
Within the slot of the current reception slot obtained by the gain normalizing means when the average reception level in the slot before the frame is changed and output to the inter-slot average calculating means, and the determination by the level difference determining means is otherwise 2. The TDMA data receiving apparatus according to claim 1, further comprising: intra-slot reception level replacing means for outputting the average reception level as it is to the inter-slot average calculating means. 3. The average reception level in the slot of the current reception slot obtained by the gain normalizing means is divided by the average reception level in the slot one frame before, and it is determined whether or not the division result is smaller than a set threshold value. 7. A level difference determining means for determining and a scaling factor generating means for switching the value of the scaling factor output to the second multiplying means based on the determination result of the level difference determining means. 1. The TDMA data receiving device according to 1. 4. The average reception level in the slot of the current reception slot obtained by the gain normalizing means is divided by the average reception level in the slot one frame before, and it is determined whether or not the division result is smaller than a set threshold value. Level difference determining means to determine, when the level difference determining means determines that the division result is smaller than a threshold value, to the average reception level within the slot of the current receiving slot obtained by the gain normalizing means,
Multiply a coefficient proportional to the reciprocal of the division result and output to the inter-slot average calculating means, and when the determination of the level difference determining means is other than that, of the current reception slot obtained by the gain normalizing means 2. The T according to claim 1, further comprising level control means for outputting the average reception level in the slot as it is to the inter-slot average calculation means.
DMA data receiving device. 5. The TDMA data receiving apparatus according to claim 1, further comprising linear-log conversion means for converting the output of the first multiplication means into a logarithmic value.