JPH0440038A - Radio equipment - Google Patents

Abstract

PURPOSE:To reduce the error rate of data communication and to improve throughput by providing a level fluctuation suppressing measn at the alternating current coupling terminal of a band limit filter. CONSTITUTION:The level fluctuation suppressing means composed of a waveform clamp circuit 4 and diodes 2a and 2b is provided at the alternating current coupling terminal of a band limit filter part 5, and an output terminal 6 is connected to a carrier osicllator as a signal to modulate a carrier. Therefore, even when a modulated data is changed from the state of no change in the modulated data, the fluctuation can be eliminated in the direct current component at the alternating current coupling terminal of the band limit filter part 5. Thus, the desired data to be communicated is speedily modulated and the data error rate is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a wireless device that performs digital data communication.

[Summary of the Invention] The present invention provides a radio device in which a digital section that emits digital modulation data and a band-limiting filter section are AC coupled;
If you change the modulation data from a state where there is no change in the modulation data, such as when the same data has continued for a long time due to transmission suspension or no modulation, the voltage of the DC component at the AC coupling end of the band-limiting filter section will increase. The purpose is to provide a level fluctuation suppressing means at the AC coupling end of the band-limiting filter to improve the problem that the center value of the transmission frequency fluctuates due to rising or falling.

[Prior Art] FIG. 4 is a circuit diagram showing an example of a bandpass filter section in a conventional wireless device, in which 3 is a DC blocking capacitor for AC coupling with the digital section, 5 is an amplifier 4a, and resistors 4b to 4.
4f, capacitors 5g, and 5h.

Next, the operation will be explained using the waveforms shown in FIG.

Modulation data 8, which is at O volts when modulation is stopped, or modulation data 9, which is at +5 volts when modulation is stopped, is input from the digital section to input terminal 1a. In 1b, 1
The waveform of modulation data 8 or 9 is superimposed on the bias voltage of b, and is differentiated by the input equivalent resistance of the DC blocking capacitor 3 and the non-inverting active low-pass filter circuit 5, resulting in the waveform 11 shown in FIG. 3(b). Or it will be 15. Next, the output terminal 6 of the band-limiting filter section that has passed through the active low-pass filter circuit 5 is connected as shown in FIG.
Waveform 17 or 19 shown in is output. This waveform 1
7.19, not only the average voltage fluctuates, but also the waveform distortion becomes large.

Therefore, we reduced the time constant of the differentiating circuit formed by the AC-coupled DC cutoff capacitor and the equivalent load resistance so that even if a level fluctuation occurs, it recovers in a short time, or , it outputs clock-like data and starts transmission after level fluctuations have recovered.

[Problems to be solved by the invention] However, in the conventional method, by reducing the time constant of the differentiating circuit, the digital waveform to be modulated may be distorted, or the transmission may be delayed until the level fluctuation is recovered. There were disadvantages such as not being able to modulate the desired data and causing data errors after the same data continued for a long time.

[Means for Solving the Problems] Therefore, in the present invention, level fluctuation suppressing means is provided at the AC coupling end of the band-limiting filter section.

[Function] By doing the above, even if the modulation data is changed from a state where there is no change in the modulation data, fluctuations in the DC component at the AC coupling end of the band-limiting filter section can be eliminated,
You can immediately modulate the data you want to send, and
This reduces the data error rate.

[Example] Embodiments of the present invention will be described below based on the drawings.

FIG. 1 is a circuit diagram showing an embodiment of a band-limiting filter section in a wireless device according to the present invention.

3 is a DC block capacitor for AC coupling with the digital section; 4 is a waveform clamp circuit consisting of an amplifier 4a, resistors 4b to 4f, and Zener diodes 4g and 4h; 5 is an amplifier 5a, resistors 5b to 5f, and a capacitor 5g; It is an active low-pass filter circuit consisting of 5h, one end 1b of the DC blocking capacitor 3 is biased to 2.5V, and the input terminal 1a is connected to a digital section (not shown).
The waveform clamp circuit 4 and the diodes 2a and 2b constitute a level fluctuation suppressing means, and the output terminal 6 is connected to a carrier oscillator (not shown) as a signal for modulating the carrier.

FIG. 2 is a circuit diagram showing another embodiment of the band-limiting filter unit in the wireless device of the present invention, in which the same parts as in the above embodiment are given the same reference numerals, and the explanation thereof will be omitted. Reference numeral 7 denotes a Zener diode, which together with the waveform clamp circuit 4 constitutes level fluctuation suppressing means.

Next, the operation will be explained using the waveform shown in FIG.

Modulation data 8, which is at O volts when modulation is stopped, or modulation data 9, which is at +5 volts when modulation is stopped, is input from the digital section to input terminal 1a. In 1b, 2
．． The bias voltage of 5V and the modulation data 8 or 9 are superimposed, but the voltage of 1b is clamped by the diodes 2a, 2b or the Zener diode 7, and the waveform 1
0 or 14. At this time, the level fluctuation is suppressed to the forward voltage of the diodes 2a and 2b or the Zener voltage of the Zener diode 7 and the forward voltage.

In this way, a diode or a Zener diode alone can be sufficiently effective as a level fluctuation suppressing means depending on the application.

Furthermore, in the waveform clamp circuit 4, the input waveform 10 or 14 is clamped at voltages 12 and 13 by the voltages of Zener diodes 4h and 4g, and the diodes 2a and 2
b, or the slight fluctuation voltage caused by the Zener diode 7 can be clamped.

When this clamped waveform is input to the active low-pass filter circuit 5, a waveform 16 or 18 with no level fluctuation or distortion is outputted to the output terminal 6. This output waveform is used as a signal to modulate the carrier and is sent to the carrier oscillator. By inputting the signal, it is possible to perform modulation with a stable modulation degree without fluctuations in the center frequency. Furthermore, since there is no need to consider the return time after level modulation, the differential time constant described above can be increased, and even data that continues for a long time can be stably modulated.

[Effects of the Invention] According to the present invention, in a radio device that AC couples a digital section that generates a modulated signal and a band-limiting filter section, it is possible to perform modulation with a stable modulation degree without center frequency fluctuation, and, This allows modulation with a low modulation frequency to be applied, reducing error rates in data communications and improving throughput.

[Brief explanation of the drawing]

1 and 2 are circuit diagrams each showing an embodiment of a band-limiting filter section provided with a level fluctuation suppressing means in a wireless device of the present invention, and FIGS. FIG. 4 is a circuit diagram showing an example of a band-limiting filter section of a conventional wireless device. 1 a ・ 2 a, 3 ・ ・ 4 ・ ・ 5 ・ ・ 6 ・ ・ ・ ・ 7 ・ ・ ・ ・ ・ Input terminal diode DC blocker capacitor Waveform clamp circuit Active low-pass filter circuit Output terminal Zener diode and above Applicant Seiko Electronics Kogyo Co., Ltd. Agent Patent Attorney Keisuke Hayashi Figure 3 (a) Figure 1 Figure 3 (b') Figure 3 (c') Figure 2 Figure A

Claims (1)

[Claims] A wireless device that applies digital modulation directly to the transmitting section and combines the modulated data of the digital section and the band-limiting filter section by AC coupling, characterized by providing level fluctuation suppressing means at the AC coupling end of the band-limiting filter section. wireless equipment.