JPS60165122A - Level detector - Google Patents

Abstract

PURPOSE:To improve the accuracy of level detection by allowing the 1st and 2nd sub-level detectors to detect an output level of the 1st and 2nd common sections to switch the attenuation of the 1st and 2nd attenuator thereby preventing deterioration of the level detecting characteristic due to temperature. CONSTITUTION:The 1st and 2nd sub-level detectors 111, 112 detect an upper limit level point obtained for an excellent input/output linearity by using a detecting section. A controller 13 of the next stage receives an output signal of the 1st and 2nd sub-level detectors 111, 112, and when they detect that either or both reach the upper limit input level, the attenuation of the 1st and 2nd attenuators 121, 122 is switched at the same time. The attenuation is set to the 1st and 2nd linear region of the level detection section.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a level detection device in a working/protection transmission line channel of a communication system that requires a stable level detection function over a wide range of temperatures.

(Prior technology) 8CPC communication method (Sin
gle Channel Per Channel)
In a common part, for example, a common amplifier or a frequency conversion part, the common part includes several tens of channels when the signal passing through the common part belongs to the transmitting system, and several hundred channels when it belongs to the receiving system. Only when a double signal audio signal is present, it passes through the common part in a temporally disordered manner. For this reason, when determining a failure in a common section consisting of working/protection channels, a special level detection device with high accuracy over a wide range has been required.

Therefore, conventionally, a level detection device having a configuration as shown in FIG. 1 has been employed. In FIG. 1, ii,
12 are first and second common parts, 21 and 22, respectively.
31 and 32 are first and second level detectors, respectively, 41 and 42 are first and second logarithmic amplifiers, 5 is a comparator, and 6 is a comparator.
is a judge, and 7 is a switch.

In the level detection device shown in FIG. 1, first and second demultiplexers 21 and 22 are respectively connected from first and second common parts 11 and 12 consisting of working/protection channels.
A portion of the signal obtained through the DC signal is converted into a DC signal by the first and second level detectors 31 and 32, respectively.

The outputs of the first and second level detectors 31 and 32 are
The signals are logarithmically converted by first and second logarithmic amplifiers 41 and 42, respectively. first and second logarithmic amplifiers 41,
The signals from 42 are both applied to comparator 5, and the output levels are compared with each other by a built-in differential amplifier circuit. The determiner 6 simultaneously compares and determines whether the levels are high or low between the two channels and determines the level difference. Judgment device 6
The output is applied to the switch 7 to provide redundancy to the first and second common sections 11 and 12, and is used as a switching control signal for the switch 7.

In order to use the above prior art level detection device as a good level detection device over a wide input range, K is:
Generally, it is necessary to set the operating points of the first and second level detectors, which are constructed with diode pressure sensors, low, and they are used inside the first and second logarithmic converters 41 and 42 in the next stage. The operational amplifier circuit also needs to have low drift characteristics and low input offset characteristics, making it expensive. Furthermore, since the above-mentioned level detection device has a low operating point, there is a drawback that level detection accuracy and level detection characteristics are significantly degraded by temperature.

(Object of the invention) The object of the invention is to provide first and second main level detectors;
First and second sub-level detectors and first and second attenuators are additionally provided at the input section of the two-channel level detection section consisting of the first and second logarithmic amplifiers, respectively; Output level ′(il
- detecting by first and second sub-level detectors, eliminating the above-mentioned drawbacks by switching the attenuation amounts of the first and second attenuators, and having a low-cost and wide level detection range;
It is an object of the present invention to provide a level detector @ whose level detection characteristics are relatively less deteriorated by temperature.

(Structure of the Invention) A level detection device according to the present invention includes first and second sub-level detectors, a controller, first and second attenuators,
first and second main level detectors and i@1 and second
The circuit is configured to include a logarithmic amplifier, a comparator, a determiner, and a switch.

The first and second sub-level detectors are provided in the working channel and the protection channel, respectively, and are for inputting and detecting a part of the signal of the working channel and a part of the signal of the protection channel.

The controller operates in response to the outputs of the first and second secondary level detectors, and is operable to control the outputs of the working channel and the protection channel.
This means that the s-th attenuation amount can be controlled individually.

The first and second attenuators are individually controlled by a controller to set the amount of signal attenuation for each individual channel so that the signal attenuation is applied to the other part of the signal of the working channel and the other part of the signal of the protection channel. It is not allowed to pass through.

The first and second main level detectors are for detecting the output signal levels of the first and second attenuators.

The first and second logarithmic amplifiers are for logarithmically amplifying the outputs of the first and second main level detectors, respectively.

The comparator receives the output signals of the first and second logarithmic amplifiers and compares the signal level of the working channel with the signal level of the protection channel.

The determiner is used to determine whether the signal levels input to the individual channels are high or low, and to determine the level difference based on the output of the comparator.

The switch is for switching to select a protection channel when the signal level of the working channel is at the limit value according to the output of the determiner.

Embodiments) Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

Figure $2 is a block diagram showing an embodiment of the level detection device according to the present invention. In Figure 2, 11, 1
2 are the first and second common parts, 21 and 22 are the first and second demultiplexers, respectively, 311 and 312 are the first and 'second main level detectors, respectively;
42 are first and second logarithmic amplifiers, 5 is a comparator, 6 is a determiner, 7 is a switch, 111 and 112 are first and second sub-level detectors, respectively, 121 and 12
2 is a first and second attenuator, and 13 is a controller.

In the present invention, first and second sub level detectors 11 are newly added to the conventional level detecting device shown in FIG.
i, 112, and first and second attenuators 121,
122 is added to configure a level detection circuit.

FIG. 3 shows first and second sub-level detectors 111,
112, first and second main level detectors 311,
312 and the first and second logarithmic amplifiers 41 and 42. FIG.

As shown in FIG. 2, the signals from the first and second common sections 11 and 12 that have passed through the first and second branching filters 21 and 22, respectively, are sent to 'iA1' provided for each channel.
and the first and second main level detectors 311, 312, the first and second The signal is input to a level detecting section consisting of logarithmic amplifiers 41 and 42.

The input/output directivity of the level detecting section generally has three regions depending on the input level, as shown in FIG. 1st
The region is a region where linearity is good but the level is low and therefore easily affected by temperature, and the second region is a region where good linearity is obtained with relatively little influence by temperature. The third region is a region where good linearity cannot be obtained.

The first and second sub-level detections 4111 + 112 detect the upper limit input level at which good input-output linearity can be obtained in the detection section, that is, the point ■ in FIG. 3.

The next stage controller 13 receives the output signals of the first and second sub-level detectors 111 and 112, receives the output signals of the first and second sub-level detectors iii and 112,
1st and iJ! 2 sub-level detectors 111, 112
When it is detected that one or both of them has reached the upper limit input level, the attenuation amounts of the first and second attenuators 121 and 122 are simultaneously switched.

When the attenuation amount is switched and set to xdB as shown in FIG. 3, the first and second main level detectors 311 and 312
and the first and second logarithmic amplifiers 41 and 42. First and second main level detectors 31
1, 312, and first and second logarithmic amplifiers 41,
The stages after 42 adopt a configuration similar to that of FIG. First and second main level detectors 311°31
2, I81 and second logarithmic amplifiers 41 and 42,
The comparator 5 and the determiner 6 detect the height and level difference between the No. 48 levels passing through the common part of the working/protection channel. In this embodiment, in addition to the switching unit of the first and second attenuators 121 and 122, the attenuator employing an IcPIN diode, and the first and second sub-level detectors 111 and 112, the level By connecting detectors in parallel in multiple stages, it is possible to perform highly accurate level detection over a wider range.

(Effects of the Invention) As explained above, the present invention provides two main level detectors including first and second main level detectors and first and second logarithmic amplifiers.
First and second sub-level detectors and first and second attenuators are additionally provided at the input section of the level detection section of the channel, respectively, and the signal level from the first and second common section is additionally provided. is detected by the first and second sub-level detectors, and by switching and setting the attenuators of the first and second attenuators, the operating point of the level detector is less affected by temperature and the detection accuracy is improved. Since it can be set within a good range, there is no need for expensive operational amplifiers or warm compensation circuits.
This has the advantage that good level detection can be performed for signals applied to the first and second common parts over a wide input range.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an example of a level detection device according to the prior art. FIG. 2 is a block diagram showing an embodiment of the level detection device according to the present invention. FIG. 3 is a diagram showing standard human output characteristics of the level detection section. 11, 12... common part 21, 22... branching filter 31, 32, ill, 1i2, 311,
312... Level detector 41, 42... Logarithmic amplifier 5... Comparator 6...
・Determiner 7... Switching device 121, 122... Attenuator 13... Controller patent applicant Hisashi Inoro, agent for NEC Corporation, patent attorney

Claims (1)

[Claims] first and second sub-level detectors provided in the working channel and the protection channel, respectively, for inputting and detecting a part of the signal of the working channel and a part of the signal of the protection channel; and a controller operated in response to the output of the second sub-level detector to individually control the signal attenuation of the working channel and the protection channel; first and second attenuators, each of which has a signal attenuation amount installed for each channel, and which allows another part of the signal of the working channel and another part of the signal of the protection channel to pass; first and second main level detectors for detecting output signal levels of the first and second attenuators; and a device for logarithmically amplifying the outputs of the first and second main level detectors, respectively. first and second logarithmic amplifiers; and a comparator for inputting the outputs of the first and second logarithmic amplifiers to compare the signal level of the working channel and the signal level of the protection channel; A determiner for determining whether the signal levels input to the side channels are high or low based on the output of the comparator and determining a level difference; and a signal level of the current channel based on the output of the determiner. 1. A level detection device comprising: a switch for switching to select the spare channel when the predetermined channel is at a limit value.