CN101944936A

CN101944936A - Narrow band carrier reduction device applied to low voltage collected meter reading

Info

Publication number: CN101944936A
Application number: CN2010102731107A
Authority: CN
Inventors: 夏水斌; 傅士冀; 陈俊; 吴佳; 李鹏宾
Original assignee: HUBEI PROV POWER TEST INST
Current assignee: State Grid Corp of China SGCC; Electric Power Research Institute of State Grid Hubei Electric Power Co Ltd
Priority date: 2010-09-06
Filing date: 2010-09-06
Publication date: 2011-01-12
Anticipated expiration: 2030-09-06
Also published as: CN101944936B

Abstract

The invention discloses a narrow-band carrier attenuation device applied to low-voltage centralized meter reading, and relates to a carrier attenuation device. The structure of the present invention is that PC upper computer, communication circuit, control logic circuit and high-frequency attenuation circuit are connected sequentially, the buttons are connected with the control logic circuit, and the switching of the attenuation range of the carrier signal is realized through program control; the carrier signal input terminal, the first The impedance matching circuit, the low-pass high-impedance filter circuit, the second impedance matching circuit, and the carrier signal output end are connected successively, and the carrier signal input end, the high-frequency attenuation circuit, and the carrier signal output end are connected successively, realizing the carrier input signal. attenuation. The invention can realize the switching of the carrier gear by program control, is easy to expand, and can work reliably and stably for a long time; it can realize uniform attenuation of the same gear for signals within the frequency range of 80 kHz to 1 MHz; it is suitable for the centralized meter reading terminal of the low-voltage carrier And the detection of the communication attenuation performance of the smart carrier energy meter.

Description

Be applied to the narrowband carrier attenuating device of low pressure centralized automatic meter-reading

Technical field

The present invention relates to a kind of carrier wave attenuating device, relate in particular to a kind of narrowband carrier attenuating device that is applied to the low pressure centralized automatic meter-reading.Specifically, the present invention relates to detection, relate in particular to detection the fade performance of communicating by letter of low pressure carrier wave centralized automatic meter-reading terminal (comprising concentrator and collector) and intelligent carrier electric energy meter to the decay of electronic equipment carrier signal.

Background technology

At present, general carrier wave attenuating device can only be decayed at the carrier wave of certain frequency range, and can not be by the amplitude of program control carrier wave decay, and extensibility is relatively poor.

Be applied to the carrier communication chip of electric power low pressure automatic meter reading system,, and different separately damping capacities arranged because there is different separately carrier modulation frequencies in different manufacturers.Along with the all-round popularization of low pressure carrier wave centralized automatic meter-reading terminal and intelligent carrier electric energy meter is in recent years used, the carrier communication performance detection to carrier meter reading terminal and intelligent carrier electric energy meter has been proposed.

General carrier wave attenuating device can't satisfy the detection of the carrier wave decay communication performance of low pressure centralized automatic meter-reading.

Summary of the invention

Purpose of the present invention just is to overcome the above-mentioned shortcoming and defect that prior art exists, and a kind of narrowband carrier attenuating device that is applied to the low pressure centralized automatic meter-reading is provided.

The object of the present invention is achieved like this:

The present invention includes the carrier signal input of target equipment under test;

Be provided with PC host computer, communicating circuit, button, control logic circuit, the 1st impedance matching circuit, low pass high resistant filter circuit, treble attenuation circuit, the 2nd impedance matching circuit and carrier signal output;

Be connected successively before and after PC host computer, communicating circuit, control logic circuit and the treble attenuation circuit, button is connected with control logic circuit, by the switching of program control realization to the carrier signal attenuation amplitude;

Be connected successively before and after carrier signal input, the 1st impedance matching circuit, low pass high resistant filter circuit, the 2nd impedance matching circuit and the carrier signal output, be connected successively before and after carrier signal input, treble attenuation circuit and the carrier signal output, realized decay carrier input signal.

Operation principle of the present invention is:

1, control section

The PC host computer sends the gear switch order to control logic circuit by communicating circuit, and control logic circuit is finished the switching of carrier wave gear according to the instruction that obtains from host computer; Button then is the man-machine interaction mode by user and control logic circuit, can directly switch gear by button.

2, carrier wave decay part

Carrier wave decay part is made up of high resistance circuit of low pass and treble attenuation circuit again.

Because two parts circuit all has amplitude-versus-frequency curve separately, therefore two partial circuit loads each other when networking cause the variation of entire circuit amplitude-frequency characteristic; Therefore at forward and backward the 1st, 2 impedance matching circuits that increased again of the high resistance circuit of low pass, be used to improve the networking characteristic of entire circuit.

The carrier signal of equipment under test is formed by stacking by power frequency component and high-frequency signal.When carrier signal from the carrier signal input by after the high resistance circuit of low pass, power frequency component can pass through smoothly, high-frequency signal then can be attenuated totally; After carrier signal is passed through treble attenuation circuit from the carrier signal input, can realize that 0DB, 40DB, 50DB, 60DB, 70DB or 80DB six select one decay.

Signal and power frequency component mutual superposition form carrier signal output behind high frequency attenuation, thereby have realized the decay to carrier input signal.

The present invention has following advantage and good effect:

1. switching that can program control realization carrier wave gear is easy to expansion, and control logic circuit has electrical isolation characteristic preferably, can work reliably and with long-term and stably;

2. can make the signal in the band limits of 80kHz～1MHz, realize that the decay of same gear and ERROR CONTROL are at ± 2DB.

3. be applicable to detection to low pressure carrier wave centralized automatic meter-reading terminal and intelligent carrier electric energy meter communication fade performance.

Description of drawings

Fig. 1 is a structured flowchart of the present invention;

Wherein:

10-PC host computer;

20-communicating circuit;

30-button;

40-control logic circuit;

50-the 1 impedance matching circuit;

60-low pass high resistant filter circuit;

70-treble attenuation circuit,

71-0DB decay, 72-40DB decay, 73-50DB decay,

74-60DB decay, 75-70DB decay, 76-80DB decay;

80-the 2 impedance matching circuit

A-carrier signal input;

B-carrier signal output.

Fig. 2 is the special test software flow pattern;

Fig. 3 is the schematic diagram of the 1st, 2 impedance matching circuits;

Fig. 4 is high frequency attenuation network 40DB amplitude-frequency characteristic figure.

Embodiment

Describe in detail below in conjunction with drawings and Examples:

One, overall

As Fig. 1, the present invention includes the carrier signal input A of equipment under test;

Be provided with PC host computer 10, communicating circuit 20, button 30, control logic circuit the 40, the 1st impedance matching circuit 50, low pass high resistant filter circuit 60, treble attenuation circuit the 70, the 2nd impedance matching circuit 80 and carrier signal output B;

Its annexation is as follows:

PC host computer 10, communicating circuit 20, control logic circuit 40 and treble attenuation circuit 70 front and back are connected successively, and button 30 is connected with control logic circuit 40, by the switching of program control realization to the carrier signal attenuation amplitude;

Be connected successively before and after carrier signal input A, the 1st impedance matching circuit 50, low pass high resistant filter circuit the 60, the 2nd impedance matching circuit 90 and the carrier signal output B, be connected successively before and after carrier signal input A, treble attenuation circuit 70 and the carrier signal output B, realized decay carrier input signal.

Two, functional block

1, the PC host computer 10

PC host computer 10 is a kind of computers commonly used, disposes special-purpose testing software.Special test software is write by the DELPHI high-level [computer, sends the gear switch order to control circuit 40 by communicating circuit 20, realizes the program control of decay gear switch.

The special test software flow comprises the following steps: as shown in Figure 2

1. standby 1;

2. ordering 2, is then to enter next step, otherwise wait command;

3. judge 3;

4. switch 4.

2, communicating circuit 20

Communicating circuit 20 is made up of high-performance ZT232 level transferring chip, finishes the conversion of serial ports 232 level to Transistor-Transistor Logic level, and communication modes can be selected RS232 or RS485.

Main effect: the conversion of Transistor-Transistor Logic level in RS232 serial ports level and the control circuit 40 in the realization PC host computer 10.

3, button 30

Button 30 is a kind of buttons commonly used.

4, control logic circuit 40

Control logic circuit 40 is a kind of modules commonly used, is made up of CPU, peripheral buffer circuit and commutation circuit, and the listing product is arranged.When CPU receives the order of PC host computer 10 transmissions or detects the input signal of button 30, after peripheral buffer circuit drives, finish the control logic function by commutation circuit.

5, the 1st, 2

impedance matching circuits

50,80

As Fig. 3, the 1st, 2 impedance matching circuits the 50, the 80th, a kind of bridge circuit of forming by the 1st, 2 inductance L 1, L2 and the 1st, 2 capacitor C 1, C2;

The two ends of the 1st capacitor C 1 are connected with the end of the 1st, 2 inductance L 1, L2 respectively, and the two ends of the 2nd capacitor C 2 are connected with the other end of the 1st, 2 inductance L 1, L2 respectively.

Along with the increase of frequency presents different input impedance, by capacitive reactance characteristic formula Rc=1/jwc, can obtain: frequency high input impedance more is more little.

The 1st impedance matching circuit 50 is mainly used in high resistance circuit 60, the 2 impedance matching circuits 80 of coupling low pass and is mainly used in coupling treble attenuation circuit 70.

6, the high resistance circuit 60 of low pass

The high resistance circuit 60 of low pass is a kind of filter circuits commonly used, adopts two-stage LC frequency selection circuit, and the power frequency component of 50Hz can be passed through, and the high-frequency signal of blocking-up power carrier is realized the isolation to high-frequency carrier signal.

7, treble attenuation circuit 70

Treble attenuation circuit 70 comprises six module 0DB decay 71,40DB decay 72,50DB decay 73,60DB decay 74,70DB decay 75 and 80DB decay 76 parallel with one another, is undertaken six by control logic circuit 40 and selects one.

Above-mentioned module is a kind of two-terminal network, and its structure is a kind of high-pass filtering circuit commonly used, and the frequency characteristic that changes circuit by the resistance that change to insert makes it finish decay to high-frequency signal; In 80kHz～1MHz signal excursion, under 3～5 ohm of input impedance situations, realize less than the decay in the 2DB error range.

Control signal by logic control circuit 40 is sent inserts different decay gears, finishes the decay of high-frequency carrier signal 0DB, 40DB, 50DB, 60DB, 70DB, six gears of 80DB.

Three, experiment situation

Be that example is described the experiment situation with decay 40DB now, the rest may be inferred for other.

1, experiment content: measure the precision of attenuating device at 40DB decay gear.

2, laboratory apparatus: attenuating device, TDS210 oscilloscope, AFG3201 signal generator and frequency spectrograph.

3, method of measurement:

1) on attenuating device, adds the voltage signal of carrier frequency in 80kHz～1MHz scope, attenuating device is switched to the 40DB gear, with carrier signal input A input and the record numerical value of carrier signal from attenuating device, with the amplitude output signal of the carrier signal output B of oscilloscope measurement attenuating device and write down numerical value, calculate measurement result.

2) under the situation of impedance matching, draw out the amplitude-versus-frequency curve and the measurement result of attenuating device with frequency spectrograph and compare.

4, measuring process

1) signal generator being adjusted to output impedance is 10 Ω, and it is 3.33 VPP that peak-to-peak value is set.

2) measure carrier signal peak-to-peak value and the carrier signal peak-to-peak value after decay that enters attenuating device respectively with oscilloscope, as shown in table 1:

From the 80kHz-1MHz input signal is (computing formula 20log output/input):

Table 1

Because there is certain error in the result who reads with oscilloscope, the difference of only analyzing maximum and minimum value here illustrates the precision of attenuating device | Umax-Umin|=|-38.6-(37.05) | and=1.55＜2DB.

3) under the situation of impedance matching, draw amplitude-versus-frequency curve in contrast as shown in Figure 4 with sweep generator.

Solid vertical line is that the attenuation amplitude of 80kHz signal is-39.6148DB;

Vertical dotted line is that the attenuation amplitude of 1MHz signal is-40.0834DB.

Experiment conclusion:

In the scope that error allows, theory is consistent with actual value.

Claims

1. A narrow-band carrier attenuation device applied to low-voltage centralized meter reading, including a carrier signal input terminal (A) of the device under test; characterized in that:

It is equipped with PC host computer (10), communication circuit (20), button (30), control logic circuit (40), first impedance matching circuit (50), low-pass high-impedance filter circuit (60), and high-frequency attenuation circuit (70), a second impedance matching circuit (80) and a carrier signal output terminal (B);

PC host computer (10), communication circuit (20), control logic circuit (40) and high-frequency attenuation circuit (70) are connected successively before and after, buttons (30) are connected with control logic circuit (40), and the carrier wave is realized through program control Switching of signal attenuation range;

The carrier signal input terminal A, the first impedance matching circuit (50), the low-pass high-impedance filter circuit (60), the second impedance matching circuit (90) and the carrier signal output terminal (B) are connected successively, and the carrier signal input terminal ( A), the high-frequency attenuation circuit (70) and the carrier signal output terminal (B) are sequentially connected to realize the attenuation of the carrier input signal.

2. The carrier attenuation device according to claim 1, characterized in that:

The first and second impedance matching circuits (50, 80) are bridge circuits composed of first and second inductors (L1, L2) and first and second capacitors (C1, C2);

The two ends of the first capacitor (C1) are respectively connected to one end of the first and second inductors (L1, L2), and the two ends of the second capacitor (C2) are respectively connected to the other ends of the first and second inductors (L1, L2). .

3. The carrier attenuation device according to claim 1, characterized in that:

The high-frequency attenuation circuit 70 includes six modules connected in parallel: 0DB attenuation (71), 40DB attenuation (72), 50DB attenuation (73), 60DB attenuation (74), 70DB attenuation (75) and 80DB attenuation (76) ;

The above-mentioned module is a two-terminal network, and its structure is a high-pass filter circuit.