JPS59182660A - Carrier regenerating circuit - Google Patents

Abstract

PURPOSE:To attain carrier regeneration with high speed synchronism and low noise by holding a switching means to ON-state when the nonmodulating part of a received burst signal is detected to input an output signal to a carrier regenerating circuit. CONSTITUTION:When a burst receiving signal is inputted and a synchronizing pattern CR of the carrier regenerating circuit of the head part of the receiving signal is inputted, a nonmodulating part detecting signal is outputted from a nonmodulating part detector 8, an AND gate 9 is turned off to control the switching device 1 to the ON-state. A large input power is inputted to the carrier regenerating circuit 2 in this case, it is transmitted to a tracking type filter 4 and the circuit 2 attains tracking synchronism in high speed. When the clock regenerating circuit synchronism pattern STR next to the pattern CR is transmitted, zero is outputted from the detector 8, the gate 9 is turned on, the switching device 1 is on/off-controlled, and the part arranged with the phase and amplitude near the convergence only is cut out and the result is inputted to the circuit 2. Thus, the carrier regenerating signal with improved C/N ratio is outputted and the high speed synchronism and excellent C/N ratio output which are contrary conditions to each other are performed at the same time.

Description

[Detailed Description of the Invention] [Technical Field of the Invention] The present invention relates to PSK-TDMA used in satellite communications, etc.
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The present invention relates to a reference carrier regeneration circuit used in a communication system receiving device, and particularly relates to a carrier regeneration circuit that simultaneously satisfies contradictory conditions of high-speed synchronization and low noise.

[Conventional technology and problems]

Conventionally, as a means for regenerating a low-noise reference carrier wave in a PSK-TDMA communication system receiving device, the received signal is opened and closed by a regenerated clock signal using the so-called sampling method, which has the configuration shown in FIG. A method has been proposed to reduce bib noise by cutting off the irregular portions.

Next, the outline will be explained with reference to FIG.

In the PSK modulation method, the phase of a carrier wave is switched according to digital information for transmission, and on the receiving side, the phase of the reference carrier wave and the phase of this received signal are compared to demodulate the digital information. At this time, it is necessary to limit the band due to constraints on the transmission path, and therefore the phase and amplitude of the modulated wave are also distorted, as shown in the eye pattern of FIG.

Points indicated as convergence points of Tl, TR, Ts...
Only one point in each symbol has a definite phase and amplitude. However, there are many phase fluctuations in the middle part, and even if such a part is reproduced, jitter still exists. Therefore, as shown in FIG. 2 (b), the convergence point Tx of this eye pattern is
TR...Extract only the surrounding area using the clock, and
By extracting a signal like the one shown above and reproducing the carrier wave using this signal, it is possible to obtain a reference carrier wave without jitter components.

Therefore, as shown in FIG. 1, the output pulse of the clock regeneration circuit 6 is phased by the phase shifter 7 to control the on/off of the switch 1, and the convergence point Tx, as shown in FIG.
A signal only in the vicinity of TR is extracted and sent to a carrier wave reproducing circuit 2 to reproduce a reference carrier wave.

This carrier wave regeneration circuit 2 includes a multiplier 3. It is composed of a tracking type P-wave device 41, a frequency divider 5, and the like. In the case of the phase PSK modulation method, the multiplier 3 or the frequency divider 5 will respectively multiply the signal by a factor of 1 or divide the frequency by a factor of 1. Also, when the input frequency etc. fluctuates, the phase of the output frequency does not fluctuate.

After using a tracking type voice wave generator 4 whose filter center frequency follows this variation, the phase variation of the reproduced carrier wave is suppressed and the signal-to-noise ratio (C/N) is improved.

The signal that has been multiplied by the multiplier 3 is then frequency-divided by the frequency divider 5 to return it to its original frequency, thereby obtaining a reference carrier wave.

By the way, what can be obtained from carrier wave regeneration means?

The reference carrier wave that is output must have low noise and can be tracked and synchronized at high speed with respect to modulated waves received in bursts. In other words, the format of the received signal is as shown in FIG. degree phase) ST
R, a unique word UW consisting of a station identification signal such as a source address and a destination address, and a signal for removing phase uncertainty, and data DATD. In order to accurately identify the station of the unique word, synchronization must be established by this part, but the carrier wave regeneration circuit synchronization pattern CR and the clock regeneration circuit synchronization pattern ST
R is a fixed length (depending on the system) and cannot be made longer. Therefore, a carrier regeneration circuit that can track and synchronize at high speed with respect to modulated waves received in bursts and has a high C/N. Is required.

However, it is the tracking filter 4 that determines the synchronous speed and C/'N, but these are contradictory conditions as follows. In other words, in order to achieve high-speed synchronization, it is necessary to widen the bandwidth and provide a large input to the tracking type P-wave device 4.
This is because the pulse width in FIG. 2(b) is widened to lengthen the ON state of the switch 1, and a large component of phase fluctuation is inputted, resulting in a poor C/N ratio. Conversely, in order to improve the C/N and achieve a low C/N, it is necessary to narrow this bandwidth.

In response to these conflicting conditions, in the clock sampling method shown in FIG. 1, as described above, the regenerated clock shown in FIG. Cut out the nearby signal, 2-phase,
Input only the part with the same amplitude to the tracking type F wave a4 and
N is improved.

By the way, the problem with such a conventional system is that the unmodulated carrier wave regeneration circuit synchronization pattern CR part, which is the beginning of the burst shown in FIG. Since υ is controlled on/off, the received energy in this part may drop significantly and high-speed synchronization may be impaired.

[Purpose of the invention]

The purpose of the present invention is to improve such problems,
It is an object of the present invention to provide a carrier wave recovery circuit that can simultaneously satisfy the requirements of high-speed synchronization and high C/H in a PSK-'rDMA communication system receiving device.

[Structure of the invention]

In order to achieve this object, the carrier wave regeneration circuit of the present invention includes a clock regeneration means, a phase shift means, and an opening/closing means, and controls the opening/closing means according to the clock obtained by the clock reproducing means, and outputs the output of the opening/closing means. In a carrier wave regeneration circuit configured to transmit a signal to a carrier wave regeneration means having a tracking type P wave means to regenerate an =Mf transmission wave, a non-modulation portion detection means for detecting a non-modulation portion of a received burst signal is provided. When the non-modulated portion detection means detects the non-modulated portion, the switching means is controlled to be kept in an on state, and the output signal of the switching means is input to the carrier wave regeneration circuit. do.

[Embodiments of the invention]

An embodiment of the present invention will be described based on FIGS. 4 to 6.

FIG. 4 is a block diagram of an embodiment of the present invention, FIG. 5 is an explanatory diagram of its operation, and FIG. 6 is an example of a non-modulated portion detector and an explanatory diagram of its operation.

In the figure, parts with the same symbols as the others indicate the same parts, 8 is a non-modulated part detector, 9 is an AND gate, 10 is a band p wave detector, 11 is an envelope detector, and 12 is a voltage comparator.

The non-modulated part detector 8 detects the non-modulated carrier regeneration circuit synchronization pattern CR at the beginning of the received signal in the format shown in FIG. 6(a).

As shown in FIG. 6(a), the band shifter 10. Envelope detector 11. It is composed of a voltage comparator 12 and the like.

Therefore, as shown in FIG. 6(b), when the carrier wave regeneration circuit synchronization/g turn CR is input, the carrier wave frequency f is passed through the bandpass filter IO.

When this is detected by the envelope detector 11, an envelope detection output is generated as shown in FIG. 6(c). This envelope detection output is compared with a threshold value TH by a voltage comparison 612, and when this threshold value TH is exceeded, a non-modulated part detection signal is output as shown in FIG. input to the terminal. Therefore, when the non-modulated part detection signal is output from the non-modulated part detector 8, the AND gate 9 is turned off. Note that when the carrier wave is modulated, its carrier frequency f,
The power becomes weaker and the power is dissipated into other components, so the output of the envelope detector 11 only corresponds to the non-modulated carrier regeneration circuit synchronization pattern CR portion.

For each signal after the clock regeneration circuit synchronization pattern STR, an output smaller than the threshold value TH is sent out.

Therefore, in one embodiment of the present invention shown in FIG. 4, when a burst reception signal is input.

When the carrier wave regeneration circuit synchronization pattern CR at the beginning part is input, the non-modulation part detector 8 outputs the non-modulation part detection signal as shown in FIGS. 5(b) and 6). The gate 9 is turned off and the switch 1 is turned on. Therefore, at this time, a large input power is input to the carrier wave regeneration circuit 2.

This large input power is transmitted to the tracking type door wave device 4.

Therefore, this carrier wave regeneration circuit 2 achieves tracking synchronization at high speed. When the next clock regeneration circuit synchronization pattern STR after the carrier wave regeneration circuit synchronization pattern CR is transmitted, zero is output from the non-modulation section detector 8, and the AND gate 9 is turned on.9. This time, as shown in Figure 5), the recovered clock from the clock recovery circuit 6 is applied to the switch 1 via the phase shifter 7 and the AND gate 9, thereby! The switch 1 is controlled to be turned on and off. As in the conventional case shown in Fig. 1, as shown in Fig. 2,
Only a portion near the convergence point where the phase, amplitude, etc. are uniform is cut out and inputted to the carrier wave regeneration circuit 2. Therefore, if a carrier wave reproduction signal with an improved C/N ratio is outputted this time, the result will be as follows. In this way, the problem of high speed synchronization and good C/N output can be solved.

Of course, when there is no received signal, the opening/closing 61 is controlled on/off by pulse output due to noise. Therefore, the clock regeneration circuit is, for example, a voltage controlled oscillator V
When configured using a CO, the control signal of this vCO will vary greatly in frequency in proportion to the noise power. However, when there is no signal, switch l is turned on.
Since the noise power can be suppressed by turning it off, the frequency fluctuation of the VCO can also be suppressed to a small level.

In the above explanation, the present invention has been explained with reference to an example in which a frequency-multiplying type carrier wave regeneration circuit is used, but of course, the application of the present invention is not limited to this only, and can be applied to inverse modulation, remodulation, Costas type, etc. A similar effect can be obtained by using the above-mentioned membrane transmission regeneration circuit.

〔Effect of the invention〕

According to the present invention, the contradictory problems of high-speed synchronization and low-noise carrier wave regeneration can be solved with a very simple configuration.

[Brief explanation of the drawing]

Fig. 1 shows a conventional carrier wave recovery circuit using the clock sampling method, Fig. 2 shows its operation circuit, Fig. 3 shows its signal format, Fig. 4 shows the configuration of an embodiment of the present invention, and Fig. 5 shows its operation explanation. , FIG. 6 is an example of a non-modulated portion detector and an explanatory diagram of its operation. In the figure, 1 is a switch, 2 is a carrier wave regeneration port 4.3 is a multiplier,
4 is a tracking type p-wave device, 5 is a frequency divider, 6 is a clock recovery circuit, 7 is a phase shifter, 8 is a non-modulation part detector, 9 is an AND gate, and 10 is a bandpass filter. 11 is an envelope detector, and 12 is a voltage comparator. Patent Applicant: Fujitsu Limited Representative Patent Attorney Akira Yamatani, Sakae QX)

Claims (1)

[Claims] The switching means is provided with a clock reproducing means, a phase shifting means, and an opening/closing means, and the opening/closing means is controlled according to the clock obtained by the clock reproducing means, and the output signal of the opening/closing means is a carrier wave having a tracking type F-wave means. In a carrier wave reproducing circuit configured to transmit a carrier wave to a reproducing means and reproduce the carrier wave. A non-modulated part detecting means for detecting a non-modulated part of the received burst signal is provided, and when the non-modulated part detecting means detects the non-modulated part, the opening/closing means is controlled to be kept in an on state, and the opening/closing means is controlled to be kept in an on state. A carrier wave regeneration circuit characterized in that the output signal of the means is input to the carrier wave regeneration circuit.