JPS583353A - Delay detection circuit - Google Patents

Abstract

PURPOSE:To keep almost constant phase amount with a delay circuit at all times, by returning a DC fluctuation component produced by frequency fluctuation of a modulated wave to the delay circuit via a loop circuit and variably controlling the amount of delay. CONSTITUTION:A delay circuit 20 consists of a shift register 20a and a voltage controlled oscillator 20b, and a delay modulated wave signal outputted from a tap of the amount of delay of one-bit or below of a base band signal of the circuit 20 is applied to a sinusoidal wave phase comparison circuit 22 and the phase is compared with the modulated wave signal from a terminal 10. The output of the circuit 22 varies the amount of delay of the circuit 20 according to the frequency fluctuation of the modulated wave with a loop circuit to the oscillator 20b via an LPF 24 and an amplifier circuit 26. Thus, even if the modulated wave signal has a fluctuation in frequency, the phase of the delay circuit can almost be kept constant.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a nine-way detection circuit configured to eliminate eye pattern deterioration of a reciprocating signal caused by frequency fluctuations of a modulated wave.

In digital mobile communications, in order to make effective use of power and the waste #La band, a modulation method that satisfies the following conditions is required: ■ Appropriate funding for nonlinear transmission paths, and ■ Narrow occupied frequency bandwidth. be done. There exists a phase-continuous FmK modulation system (frequency shift middle-indah), that is, an mt modulation system, which satisfies the former (1) O condition but has a modulation index αs. However, this modulation method does not satisfy the conditions (1) and (9), and the modulation method adds band limitation to the modulated baseband signal using a Nyquist filter, thereby satisfying the conditions (2) and (2). is used.

As means for demodulating a modulated wave by modulating M8, a synchronous detection method, a delay detection method, etc. are known. In mobile communications, the delay detection method is advantageous when considering moderate speed-up of circuit pull-in during ray-7-aison operation, burst mode operation, and press-on/off operation and componentization of the system O configuration. It is.

FIG. 1 is a block diagram of a conventional delay detection circuit. As shown in the figure, the conventional circuit of this type includes a delay circuit 12 which provides a delay amount of 1 bit or 2 bits of the baseband signal to the modulated wave signal applied through the terminal 10;
It is comprised of a sine wave or sinusoidal wave phase comparison circuit 14 for performing phase ratio IIR between a modulated wave signal and a delayed modulated wave signal, a rhonus filter 16, and a data output terminal 18.

Note that when using the sine wave phase comparator circuit commonly used in the delay unit tIL circuit, the code amount interference is significantly large when using the nine modulation method that limits the band of the baseband signal. This is not practical because the turn is significantly degraded, and therefore, in such cases, a cosine wave phase comparator circuit that is resistant to intersymbol interference is used.

As mentioned above, the delayed detection circuit has the advantage of having a simpler configuration and no loss of synchronization than the synchronous detection circuit, but in the conventional O delay circuit, the amount of delay is always constant. Therefore, when a frequency fluctuation occurs in the modulated wave signal input, the phase error between this modulated wave signal and the delayed modulated wave signal obtained by spreading 1 or 2 bits in the delay circuit becomes large (1k), and the demodulated signal The problem is that the eyelid turn deteriorates.

Therefore, the purpose of the present invention is to solve the above-mentioned nine problems of the prior art), and the object of the present invention is to prevent the eye pattern of the demodulated signal from deteriorating even if the frequency fluctuation of the modulated wave signal occurs. The purpose of the present invention is to provide a detection circuit.

The features of the present invention that achieve the above object include a delay circuit that delays a modulated wave signal, and a phase that compares the phase of the first delayed modulated wave signal delayed by the scissors delay circuit and the modulated wave signal. In a delay detection circuit equipped with a comparator circuit, a 20th far-extended modulated wave signal p which has been given a delay amount of 1 bit or less of the baseband signal is extracted from the delay circuit, and the 20th
A closed loop circuit including a sine wave phase comparison circuit that performs a phase comparison between a far-reaching modulated wave signal and the modulated wave signal, and a loop filter that smoothes the output signal from the scissor sine wave phase comparison circuit and determines a loop response. The present invention further includes providing an output of the loop 7 circuit and returning the output of the loop 7 circuit to the delay circuit to control the amount of delay of the axillary delay circuit.

The present invention will be explained in detail below with reference to Examples.

FIG. 2 is a block diagram of a first embodiment of the present invention. This embodiment consists of the basic structure of the present invention. In this figure, the same reference numerals as in FIG. 1 represent the same parts. The delay circuit 16 has a tag that provides a delay amount of 01 bit or 2 bits of the baseband signal to the modulated wave as well as a tap that provides a delay amount of 1 bit or less, as in the conventional one. That is, the delay circuit 20 includes a two-stage and two-stage shift register 20m and an oscillator 20. The oscillator 20b is a voltage controlled oscillator whose oscillation frequency changes according to the voltage applied to the loop f circuit (to be described later). Delayed modulated signal #Lll1 outputted from a tap with a delay amount of 1 bit or less in the delay circuit 200 is applied to a sine wave phase comparison circuit 22FC, and is compared in phase with the modulated wave signal from the terminal 10. The output of the sine wave phase comparator circuit 2201 is passed through a loop filter 24 (consisting of a loaf-arm filter) which determines the response of the loop, and a substantially direct current signal proportional to the frequency fluctuation of the modulated wave is obtained. By amplifying this signal with the amplifier 26 and using it as a control voltage for the voltage controlled oscillator 20b, the amount of delay circuit 200 can be varied in accordance with the frequency fluctuation of the modulated wave. 2, a sine wave phase comparator circuit 22, a loop filter 24, and an amplifier 26 constitute a loop fB path.

The demodulation source of the delay detection circuit is as follows: - Modulated wave signal - Let (1) be a tortoise expressed by the following equation.

・(1) Tomi a−−(・, t+dem(t) )
−(x) However, ω. : Angular frequency ψm(t) of the modulated wave signal : A delay amount T is complied with in the phase change delay circuit due to kMjK modulation, resulting in a nine-round modulated signal ~t) Hiroji.

・'(t-4) proverb aw(#.(t-4)+su,(t-
f)) - (2) The output of the sine wave or cosine wave phase comparison circuit 14 is...(1)...'(t-f) When passed through the p-low I filter 6, the output is! (*)aIt will be as follows.

w(t)”=”−・. '＋? m(t)-few(t-τ
)) −(3)2 ,,.

Sine liquid phase ratio I2
If the output of 11g(1) is 2! , (t″PI--1(-(t)-pm(t-r))
−(4). However, the foundation. t-(2K-) IK* r-(N-A%
cs, eK: integer, Tc&: oscillator 2 (10 oscillation period, cosine wave phase comparator circuit). Let we(t) be the output of the low/luxury filter 16.

However, -0j 2g K, r-CN-T) T
CL I K: 1 integer c1: Oscillation period of oscillation @20 Generally, when using a sine wave phase comparison circuit, T
If you use a cosine wave phase comparator circuit (for one pit of the baseband signal), use fwt Te or T#2! 0 If the angular frequency of the modulated wave signal changes by ten ω, equation (3) becomes as follows.

n1□) In equation (6), ten. The phase error of τ is (pj*)−
The eye-turn of the demodulated signal deteriorates significantly when it cannot be ignored compared to pm(t-li). Cosine wave detection demodulation eye-I
For example, when the frequency I& of the modulated signal does not vary, it will be as shown in FIG. 8, but if the frequency changes, it will be as shown in FIG. Nine dashi, both figures 2
In the case of zero delay, there is "C." On the other hand, in the present invention, as described above, the function of controlling the oscillation frequency of the voltage controlled oscillator 20 of the delay detection circuit 20 in response to frequency fluctuations and controlling the amount of delay is provided. Since it has this feature, it is possible to eliminate 87N deterioration of the demodulated signal.

Next, the response of the loop according to the invention is shown.

"-(7) v, s+±G' y-^,・TI-f俤) is ±j town, m±1G'i"ノ・.・yf,)'ll)
g−±, −jss, −Fli)−(8) From equation (5), ω, ymg[ll, ym(N−y)”cl−”)
The angular frequency of the modulated wave signal is ω. When Shinoω changes, in the case of open loop, in the case of Kuro'-nodrug, (伽.±No,)(T时jr)冨2KK±71
,-,H.

If the compression ratio of is α-, then the equations (7) to (b) are as follows.

Figure 5 shows the relationship between the frequency fluctuation (±h5) of the modulated wave signal and the output voltage of the amplifier 26. When the frequency fluctuation is 0 (Ub), the output voltage is 3.0 (to). Fig. 6 shows the oscillation frequency dominance (±j town/211
) shows the phase characteristics of the delay circuit 200 with respect to the frequency fluctuation (J/()K) of the modulated wave signal.As can be seen from FIG. Delay circuit 20 for frequency fluctuation of modulated wave in the embodiment of
It becomes 0.2 in the compression lane α- of 0 phase deviation. That is, even if the frequency of the modulated wave fluctuates, the phase within the delay detection circuit is controlled to be approximately constant, so the amount of deterioration of the demodulated eye pattern is extremely small.

Even if the delay amount of the loop circuit 20 changes due to temperature fluctuations, power supply voltage fluctuations, etc., the delayed modulated wave signal applied to the phase comparator circuit 14 and the sine wave phase comparator circuit 22 Since the delayed modulated wave signal is output from the same delay circuit 20, fluctuations in the phase amount can be compressed.

FIG. 8 is a block diagram of the second embodiment of the present invention. In the same figure, the same parts as the first embodiment (FIG. 2) are designated by the same numbers 0, that is, this embodiment Now, a q-pass filter 28, a DC blocking circuit 30, and a differential amplifier 32 are provided as a DC component extraction circuit between the sine wave phase comparison circuit 22 and the loop filter 24 of the loop circuit of the first embodiment. There is.

The output signal of the sine wave phase comparison circuit 22 is applied to a low pass filter 28. The output signal waveform of the 4-Δ filter 280 is as shown in Figure 9. In the same figure, (4) is the waveform when there is no frequency fluctuation in the modulated wave signal, and (B) and (C) are the waveforms when there is frequency fluctuation O, respectively. The output of 28 is applied to a DC blocking circuit 300 Å made up of a capacitor, etc., and becomes a reference signal from which fluctuations in the DC component caused by frequency fluctuations of the modulated wave are removed. FIG. 10 shows the output waveform of the DC blocking circuit 30. This output (reference signal) is applied to each of the five inputs of the differential amplifier 32 together with the output of the low-pass filter 28, so that the difference The output signal of the differential amplifier 32 becomes a DC signal proportional to the frequency fluctuation of the modulated wave signal.The output signal of the differential amplifier 32 is passed through the loop filter 24 that determines the loop response, and is further amplified by the amplifier 26. ,
11 and 12 show the output signal waveforms of the differential amplifier 32 and the loop filter 24, respectively, which are applied as a control voltage to the voltage controlled oscillator 20k. In both figures, a has zero frequency fluctuation, b has +4-0.・Ha-
No ω. This is the case.

FIG. 13 is a block diagram of a third embodiment of the present invention.

This example and 1 of 2 happiness! The difference from the embodiment (No. 11m) is that the identification circuit 34 that performs quantization is added to the DC blocking circuit 300s.
is used.

That is, in this embodiment, the output waveform of the low/arm filter 28 as shown in FIG. A reference signal is output by fixing it at @1'' level. FIG. By applying it to each input of Frequency fluctuation is Δω
, then (C) is −Δω. This is the case. Differential amplification @
When such output from 32 is input to a loop filter 24 which determines the response of rule l, its output waveform is
As shown in the figure, nine DC components can be obtained in proportion to the frequency fluctuation of the modulated wave signal. ◎Roof filter 24
After the output is amplified in the amplifier 26, it is applied as a control voltage to the voltage controlled oscillator 20b.
This is exactly the same as in the other embodiments.

As described in detail above, according to Kien W14, the delay circuit is provided with a far-reaching modulated wave signal (VF) which outputs a far-reaching modulated wave signal having an osig amount of less than 1 pin of the baseband signal.
, and a sine wave phase comparison circuit between the modulated wave signal and the modulated wave signal. From the results, we extract the DC fluctuation component O caused by the frequency fluctuation of the modulated wave, and apply this to the delay circuit. Since the delay amount is variably controlled in return, the phase amount of the delay circuit is held substantially constant even if the frequency of the modulated wave signal varies. Therefore, the deterioration of the demodulated eye pattern as in the conventional case does not occur.
According to the present invention, digital mobile communications Kl! can be provided with stability against frequency fluctuations. It is possible to satisfy all the various required conditions.

[Brief explanation of the drawing]

FIG. 1 is a professional diagram of a conventional far-over detection circuit; FIG. 2 is a professional diagram of the first embodiment of the present invention; The figure shows the output voltage characteristics of the amplifier with respect to the frequency fluctuations of the modulated wave signal, Figure 6 shows the oscillation frequency deviation characteristics with respect to the control voltage of the voltage controlled oscillator, and Figure 7 shows the characteristics of the delay circuit with respect to the frequency fluctuations of the modulated wave signal. A phase deviation characteristic diagram, FIG. 8 is a block diagram of an embodiment of the iris 2 of the present invention, FIG. 9 is a waveform diagram of the output signal of the rotor O output signal, and FIG. 10 is a waveform of the output signal of the DC blocking circuit. Figure, 1st
Figure 1 is an output signal waveform diagram of the differential amplifier, Figure 12 is an output signal waveform diagram of the loop filter, Figure 13 is a block diagram of the third embodiment of the present invention, and Figure 14 is the output of the identification circuit. Signal Waveform Diagram FIG. 15 is an output signal waveform diagram of the differential amplifier. 10.18-... terminal, 14-... sine wave or cosine wave phase comparison circuit, IL28-W-nos filter, 20-
・Delay circuit, 20a...shift register, 20b-1
Pressure controlled oscillator, 22...Sine wave phase comparison circuit, 24-
- Loop filter, 26... Multiplier, 30 - DC blocking circuit, 32 - Differential amplifier, 34 - Discrimination circuit. Patent Applicant: Fujitsu Limited Patent Originator: Tamaki, Patent Attorney, Aomi, Patent Attorney, Kazuyuki Kazukan, Patent Attorney: 1) Akira Shin, Patent Attorney, Akira Yamaguchi, Figure 3, Figure 4, Figure 5, Figure 6, Control Voltage ( V) Figure 7 Frequency fluctuation of modulated wave signal (in Hz) Figure 9 Figure 10 Figure 11 Figure 12 Figure 14 Figure 15

Claims (1)

[Claims] 1. A delay circuit that delays a modulated wave signal, and a phase comparison circuit that compares the phase of the first delayed modulated wave signal delayed by the delay circuit and the modulated wave signal. In the delay test circuit, the pacepan P signal 01 is output from the delay circuit.
A sine wave phase comparator circuit that extracts a second delayed modulated wave signal that has a magnitude equal to or less than B, G, and compares the phase of the second delayed modulated rILl1 and the modulated wave signal. and a closed loop circuit including a loop filter that smoothes the output a* from the sine wave phase comparator circuit to determine a loop response, and transmits the output of the loop fIl path to the far-flung path #I to the loop path. A delay detection circuit characterized by controlling the amount of deflection of the circuit. 2. A low/l pass filter in which the loop circuit removes harmonic components of the output of the sine wave phase comparison circuit, a DC blocking circuit that removes direct current components of the output signal of the low I4 pass filter;
A differential amplifier circuit is provided for differentially amplifying the output signal of the -1 band filter and the output signal of the DC blocking circuit, and the output signal of the differential amplifier circuit is applied to the loop filter. As described in Claim 1, the late wave detection circuit 3 and the 7 circuit are four-pass filters that remove harmonic components of the output of the sine wave phase comparator circuit!
, a rounding discrimination circuit that quantizes the output signal of the #4-Nosfil I, and a differential amplification circuit that differentially amplifies the output signal of the Ronosfil filter and the output of the discrimination circuit,
2. The delay detection circuit according to claim 1, wherein the wrinkled differential amplifier circuit 0 output signal is applied to the loop filter.