JPS6321574A - Noise measuring apparatus - Google Patents

Abstract

PURPOSE:To obtain an output voltage corresponding to a noise, by rectifying a received signal to sample an input or output of the rectification at the time when the amplitude reaches its min. at the highest probability. CONSTITUTION:When a received signal x2 contains no noise, an output x3 of an HPF3 and an output x4 of a rectifying circuit 4 have such a phase point that the amplitude becomes very small. The results of measurement of noises can be obtained by measuring the degree to which such a nature of waveform is contained. In other words, the waveform of the output x4 is sampled with a sample holding circuit 10 by a sampling pulse x9 at the when the amplitude reaches its min. to obtain a sampling signal x10. Thus, noises contained in the output x4 are determined by measuring the level of the signal x10 with a level measuring circuit 11. Any noise in the signal x2 disturbs the waveform of the output x4 and thus, the above-mentioned operation provides the measurement of noises contained in the signal x2.

Description

Detailed Description of the Invention (Industrial Application Field) The present invention relates to noise measurement of digital signals received by digital radio, and in particular to selection of digital signals in diversity reception, or whether or not to process received digital signals. This paper relates to noise measurement for obtaining squelch signals.

(Prior Art) Conventionally, in order to compare the quality (for example, bit error rate) of digital signals in diversity reception or to obtain a squelch signal for a received digital signal,
A known method is to determine the quality of a received signal by measuring the received electric field strength or the out-of-band noise of the received signal.

(Problems to be Solved by the Invention) In the conventional technology, the received digital signal and the measurement result of its quality do not necessarily correspond. Atsuku.

The first problem is that when conventional methods are applied to squelch signal detection, when the receiver receives urban noise or interference waves, it is difficult to distinguish them from the desired signal, and the squelch signal is erroneously responded to. The problem lies in the fact that it is processed incorrectly even though it is not a wave.

The second problem is that when detecting a squelch signal, the error rate of the received digital signal and the received field strength vary somewhat depending on the receiver (usually several dB).
), the squelch signal responds even when the actual received electric field strength is low and the quality of the digital signal is poor.

The third problem is that if two receivers measure all the digital signal quality using the conventional method, and if we perform diversity reception in which the output of the receiver is selected using these results, the city The measurement result of the electric field strength and the error rate cannot correspond to each other due to variations in noise and interference waves, or variations in the characteristics of the receiver itself.Finally, the signal with the best received signal quality is not always selected, and the diversity effect is at the point of deterioration.

The above problems occur not only when measuring the received electric field strength but also when measuring out-of-band noise of the received signal.

Furthermore, when measuring the total received electric field strength, there is a drawback that an expensive device such as a logarithmic amplifier must be used in order to obtain a voltage proportional to the received electric field strength.

The object of the invention is to pass the received signal through a high-pass filter,
In a receiving device that inputs the signal wave to a rectifier circuit to obtain a signal wave including a clock frequency component, and further inputs the output of the rectifier circuit to a clock pulse regeneration circuit to regenerate the entire clock pulse, the amplitude of the input or output of the rectifier circuit is A noise measurement device configured to eliminate the above drawback by sampling the point in time when the probability of minimum is highest and measuring its amplitude level, thereby obtaining an output voltage corresponding to the noise contained in the received signal. Our goal is to provide you with all that you need.

(Precautions to Solve the Problems) The noise measurement device according to the present invention is constituted by clock generation means, sample hold means, and level measurement means.

The clock generation means is for passing the high frequency component of the received signal and then rectifying it to generate a signal wave including the bottom of the C clock frequency, and further regenerating all eight clock wave number components from the signal wave.

The sample and hold means is for sampling the point in time when the amplitude of the input or output of the rectifier is the lowest and holding the entire sample level.

The level measuring means is for measuring the amplitude level of the output of the sample and hold means.

(Example) Next, the present invention will be described with reference to drawing t.

FIG. 1 is a block diagram showing an embodiment of a noise measuring device according to the present invention. In Figure 1, 'C%1 is the receiver, 2
is a low frequency F wave device, 3 is a high frequency door wave device, 4 is a rectifier circuit, 5 is a band F wave device, 6 is a comparator, 7 is a Takabetsu circuit, 8 is a delay circuit,
Reference numeral 9 designates a te/gling pulse generation circuit, 10 a sample and hold circuit, 11 a level measurement circuit, and 12 a comparator.

FIG. 2 is an explanatory diagram showing operating waveforms of each part in FIG. 1.

In FIG. 1, the output that has been damaged by a receiver 1 passes through a low-frequency F-wave generator 2 to remove noise and obtain a received signal x2. As shown in FIG. 2, the signal x2 shows an open eye pattern. Furthermore, in order to obtain the same wave number component of the clock, the signal x2 is inputted to the rectifier circuit 4 through the high-frequency P wave generator 3t-, and is rectified by the rectifier circuit 4.

Since the output of the rectifier circuit 4 includes a clock frequency component, the clock frequency component is extracted by the bandpass filter 5 and further compared with the fundamental voltage Vc1 by the comparator 6.

This rectifies the waveform and provides a regenerated clock pulse x6.

Next, using the regenerated Glock pulse xsTh, the received signal
is identified by the identification circuit 7, and the identification circuit 7 outputs an injury digital signal x7.

In the noise measuring device described above, the following can be said about clock pulse reproduction.

As shown in FIG. 2, when the received signal x2 does not contain noise, the output x3 of the high-frequency P wave generator 3 and the output x4 of the rectifier circuit 4 have a phase point (
In Figure 2, tl.

t2. ts) exists. In the present invention, noise measurement results are obtained by measuring to what extent such waveform properties are maintained. In the sample and hold circuit 10, the waveform of the signal x4 is determined by the sampling pulse x9 at the point in time when the S smoothness is the smallest (for example, %
1tz, ts). In the present invention, the total noise contained in the received signal x2 is measured by measuring all the signals at these points.

On the other hand, the waveform of signal
*ts) is sampled by the sample and hold circuit 10.

The delay circuit 8 and the sampling pulse generation circuit 9 are provided for the purpose of generating a sampling pulse at the sample and hold times %10.

The delay circuit 8 appropriately delays the clock pulse x6, and the sampling pulse generation circuit 9 generates a minute pulse St- in synchronization with the rising edge υ of the output x6 of the delay circuit 8. It is outputting. Here, the delay amount of the delay circuit 8 is adjusted in accordance with the time point at which the delay amount is minimum, such as tl, tz, and tx in X4, with respect to the rising edge of the sampling pulse x9.

As shown in FIG. 2, when the signal x4 does not contain noise, the sampled result XIG in the sample and hold circuit 10 has a zero level as shown by the solid line. As shown by the dotted line in FIG. 2, when there is noise in the signal x4, samples are made of Δv1, ΔV2, ΔVs, . . . gold, and the voltage ΔV1. Δv2. Δv3 occurs.

Therefore, when the level measuring circuit 11 measures the level of the signal XIO, it means measuring the noise contained in the rectified output x4. If there is noise in the received signal x2, the drum shape of the signal x4 will be disturbed, so the above operation can be interpreted as measuring the noise contained in the signal x2.

Next, the average value of the signal XIO is determined by the level measuring circuit 'N111, and instantaneous fluctuations in the signal xto are removed.

Next, in the comparator 12, the output Xll of the level measuring circuit 11
When it becomes larger than the value Vcz, this is regarded as a noise state and the output is raised to the level of 8Qt'''1''. In other words, in 8Q, when receiver 1 does not receive a normal signal and the eye pattern of the received signal output is not open,
It is used as a squelch signal to output 1 level. In this case, no signal processing is performed on the output x7 of the identification circuit 7.

The above explanation is based on the case where the output xak of the rectifier circuit 4 is input to the sample and hold circuit 10, but the same result can be obtained by inputting the output xsf of the rectifier circuit 4 to the input xsf sample and hold circuit IO instead.

That is, the above is clear from the fact that the waveform of the signal x3 becomes zero level at the rising edge of the sampling pulse XS shown in FIG. In this case, the level measurement circuit 11
What is necessary is to measure the AC voltage of the input XIO.

(Effects of the Invention) As explained above, the present invention passes a received signal through a high-pass filter, inputs it to a rectifier circuit to obtain a signal wave containing a clock frequency component, and further converts the output of the rectifier circuit into a clock pulse. In a receiving device that regenerates all clock pulses by inputting them to a regeneration circuit, the input or output of the rectifier circuit is
By sampling all the points at which the S corner has the highest probability of being minimized and measuring their amplitude levels, it is possible to measure the noise included in the eye pattern of the received signal. ~ There is a fourth effect.

First, there is a case where the eye pattern of the C received signal does not open due to urban noise, interference waves, etc., and there is an effect that all the received signals are determined to be noise and are measured. As a result, the conventional problem of erroneously outputting a response due to a squelch signal is solved.

Second, even if there are variations in receiver performance, a squelch response signal corresponding to the bit error rate can be obtained.

Thirdly, the present invention is applied to diversity reception, in which the measurement results of the noise included in the eye pattern of the respective received signals of two receivers are compared with each other. , it is possible to reliably select a signal with a low error rate. Therefore, there is no possibility of total deterioration of the diversity effect as in the conventional case.

Fourth, the present invention greatly simplifies circuit design, and there is no need to use expensive devices such as logarithmic amplifiers as in the conventional electric field strength measurement method. Therefore, it is advantageous in terms of price.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of a noise measuring device according to the present invention. FIG. 2 is a waveform explanatory diagram showing operating waveforms of each part of the noise measuring device shown in FIG. 1. 1... Receiver 2, 3.5... P wave device 4... Rectifier circuit 6.12... Comparator 7... Identification circuit
8...Delay circuit 9...Sampling pulse generation circuit 10...Sample hold circuit 11...Level measurement circuit xx~xu, 8Q-signal ΔVt, ΔVz, ΔVs, Vcs,
VO2-W pressure tx, tz, tx...time

Claims (1)

[Claims] a clock generating means for passing a high frequency component of a received signal and then rectifying it to generate a signal wave including a clock frequency component, and further regenerating the clock frequency component from the signal wave; A sample-hold means for sampling and holding a point in time at which the probability of the output having the lowest amplitude is the highest; and a level measuring means for measuring the amplitude level of the output of the sample-hold means. A noise measurement device featuring: