CN1750420A - Detecting control circuit for two-wire multiple signal transmission speaker in public broadcast system - Google Patents
Detecting control circuit for two-wire multiple signal transmission speaker in public broadcast system Download PDFInfo
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- CN1750420A CN1750420A CNA200410071943XA CN200410071943A CN1750420A CN 1750420 A CN1750420 A CN 1750420A CN A200410071943X A CNA200410071943X A CN A200410071943XA CN 200410071943 A CN200410071943 A CN 200410071943A CN 1750420 A CN1750420 A CN 1750420A
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Abstract
This invention discloses a loudspeaker detection control circuit of two-wire system multi-signal transmission in a public broadcast system characterizing in transmitting constant voltage audio signals, two-way carrier control signals and DC supply at the same time by the two-wire system, the three of which pass through the band-pass filters of audio signals, carrier signals and DC supply low-pass filter to be mixed and transmitted at the same time by the two-wire system, said filters take out the audio signals carries out according to the instructions to realize the fault test for several dozens to several hundreds of loudspeakers and on-off control.
Description
Technical field:
The present invention relates to a kind of wired public broadcasting transmission line.Specifically, particularly transmit level pressure audio signal, carrier control signal, dc power signal simultaneously in the two-wire system public broadcasting circuit, realize the fault detect and the Push And Release control of loud speaker.
Background technology:
At present, can connect tens of extremely hundreds of loud speakers in known wired Public Address system and form radio networks.General two lead transmission 120V or the 240V level pressure audio signal of adopting is to loud speaker.Be called for short two-wire system.But if in broadcast system, realize the fault detect of loud speaker or the control of Push And Release, at least also to increase by two lead transmission of control signals and DC power supply, form four-wire system or multiple-way system like this, could realize the fault detect of loud speaker or the control of Push And Release.Adopt the defective of multiple-way system mode to be: to increase the lead of two transmission of control signals and DC power supply in (one) known multiple-way system Public Address system, cable material is doubled, cost is multiplied; (2) in bigger Public Address system such as school, stadiums, building residence broadcasting, subway station, railway station, airport, tens of distances between hundreds of loud speakers and broadcasting equipment can reach hundreds of or thousands of rice, site operation must be distinguished the lead of level pressure audio signal and the lead of transmission of control signals, it does not allow misconnection each other, bring suitable difficulty to site operation undoubtedly, solution is not arranged so far.
Summary of the invention:
The objective of the invention is to develop a kind of loud speaker that is specially adapted to transmit with two-wire multiple signal in the Public Address system and detect control circuit.In two-wire system rated power broadcast circuit, adopt the frequency separation mode to transmit many signals, transmission when only can finish rated power broadcast audio signal, two-way carrier signal, dc power signal with two-wire system, and be independent of each other, realize the loud speaker Detection ﹠ Controling of two-wire multiple signal transmission in the Public Address system.
Another object of the present invention is to adopt the loud speaker of two-wire multiple signal transmission to detect control circuit, saved the lead of two pieces transmission of control signals and DC power supply, reduced cost, very be convenient to site operation, increase work efficiency and the reliability of broadcast system.
A further object of the present invention is to adopt the loud speaker of two-wire multiple signal transmission to detect control circuit, can not consider polarity during connecting terminal under the occasion that audio signal is not had phase place require.
The present invention is achieved through the following technical solutions: see accompanying drawing 1 or 2, it comprises level pressure audio signal band pass filter (1), carrier signal band pass filter (2), dc power signal low pass filter (3), terminal audio frequency signal bandpass filter (4), terminal low pass filter (5), terminal carrier signal band pass filter (6), terminal processes circuit (7), it is characterized in that: the level pressure audio signal is to export by level pressure audio signal band pass filter (1), two-way carrier signal is by carrier signal band pass filter (2) output or input, dc power signal is to export by dc power signal low pass filter (3), the corresponding respectively filter (1) separately of each signal, (2), (3), after its output parallel connection with terminal audio frequency signal bandpass filter (4), terminal low pass filter (5), each input of terminal carrier signal band pass filter (6) links to each other simultaneously, terminal audio frequency signal bandpass filter (4) output audio signal, terminal carrier signal band pass filter (6) receives or the feedback carrier signal, terminal low pass filter (5) output DC source signal, carry out by instruction through terminal processes circuit (7) again, realize transmitting with two-wire system in the Public Address system loudspeaker faults detection and the Push And Release control of many signals.
Level pressure audio signal band pass filter (1) comprises inductor A, capacitor B; Carrier signal band pass filter (2) comprises carrier wave coupling transformer C, resonant capacitor D; Dc power signal low pass filter (3) comprises choke E; Terminal audio frequency signal bandpass filter (4) comprises audio frequency line transformer F, loud speaker Y; Terminal carrier signal band pass filter (6) comprises carrier wave coupling transformer H, resonant capacitance G; Terminal low pass filter (5) comprises block capacitor I, bridge rectifier J, filtering capacitor K; Terminal processes circuit (7) comprises resistor L, voltage-stabiliser tube M, capacitor N, resistor O, diode P, capacitor Q, field effect transistor R, relay S, diode T, field effect transistor U, resistor V, microprocessor W, quartz crystal X; Its circuit connecting relation is that level pressure audio signal one end of input links to each other with inductor A one end, and the level pressure audio signal other end of input links to each other with capacitor B one end; The carrier signal two ends link to each other with the elementary two ends of carrier wave coupling transformer C respectively; Dc power signal one end of input links to each other with choke E one end, the choke E other end and resonant capacitor D one end, the inductor A other end, carrier wave coupling transformer H is utmost point lower end just, block capacitor I one end exchanges input one end and links to each other simultaneously with bridge rectifier J, C level upper end of the resonant capacitor D other end and carrier wave coupling transformer links to each other, C utmost point lower end of the dc power signal other end and carrier wave coupling transformer, the capacitor B other end, resonant capacitor G one end just links to each other utmost point upper end simultaneously with audio frequency line transformer F, the resonant capacitor G other end just links to each other utmost point upper end with carrier wave coupling transformer H, the first utmost point lower end of audio frequency line transformer F exchanges the input other end with the block capacitor I other end and links to each other simultaneously with bridge rectifier J, bridge rectifier J positive output end and filtering capacitor K one end, H utmost point lower end of carrier wave coupling transformer, resistor L one end, coil one end of diode T negative pole and relay S links to each other simultaneously, F utmost point upper end of audio frequency line transformer and loud speaker Y one end, bridge rectifier J negative output terminal, the filtering capacitor K other end, the source electrode of field effect transistor R, the source electrode of field effect transistor U, resistor O one end, capacitor Q one end, voltage-stabiliser tube M is anodal to link to each other simultaneously with microprocessor W the 8th pin, the resistor L other end links to each other with microprocessor W the 1st pin simultaneously with voltage-stabiliser tube M negative pole, quartz crystal X two ends link to each other with the 3rd pin with microprocessor W the 2nd pin respectively, H utmost point upper end of carrier wave coupling transformer links to each other simultaneously with the drain electrode of capacitor N one end and field effect transistor R, the capacitor N other end links to each other with diode P positive pole simultaneously with the resistor O other end, diode P negative pole links to each other with microprocessor W the 4th pin simultaneously with the capacitor Q other end, the loud speaker Y other end links to each other with resistor V one end simultaneously with switch one end of relay S, F utmost point lower end of the switch other end of relay S and audio frequency line transformer links to each other, the resistor V other end links to each other with microprocessor W the 5th pin, microprocessor W the 7th pin links to each other with the grid of field effect transistor R, microprocessor W the 6th pin links to each other with the grid of field effect transistor U, and the drain electrode of field effect transistor U links to each other with diode T positive pole simultaneously with the other end of relay S coil.
The audio signal of terminal audio frequency signal bandpass filter (4) output is connected to loud speaker through relay S; The carrier signal that terminal carrier signal band pass filter (6) is received is delivered to microprocessor W after diode P detection; The carrier signal of feedback is delivered to H the utmost point upper end of carrier wave coupling transformer in the terminal carrier wave band pass filter (6) after field effect transistor R amplifies, finish the transmission of its two-way carrier signal; Microprocessor W is connected to loud speaker through resistor V and finishes fault detect; The Push And Release control signal of loud speaker is amplified pusher motor type relay S through field effect transistor U and is finished.
Be meant audio signal, two-way carrier signal, dc power signal with many signals of two-wire system transmission; The two-way carrier signal of transmission is meant that the carrier signal of carrier signal band pass filter (2) output is received by terminal carrier wave band pass filter (6), and the carrier signal of feedback is sent carrier signal band pass filter (2) two ends back to through terminal carrier wave band pass filter (6); Terminal audio frequency signal bandpass filter (4), terminal low pass filter (5), terminal carrier wave band pass filter (6), terminal processes circuit (7) compositing terminal part.
In a two-wire system Public Address system, can connect a plurality of or hundreds of terminal parts and loud speaker.
Advantage of the present invention and good effect: in (one) public wired broadcast system between broadcasting equipment and the terminal speaker, only adopt two-wire system transmission 120V level pressure audio signal, transmit modulated carrier control signal, dc power signal, it is undamped each other, realizes that loudspeaker faults detects and Push And Release control.Thoroughly solved the defective of existing multiple-way system; (2) because appearance of the present invention has realized only adopting two-wire system to transmit many signals, construction can be reduced cost, be convenient to very much in broadcast system, particularly can under the occasion that audio signal is not had phase place require, polarity can be do not considered during connecting terminal.
Description of drawings
Accompanying drawing 2 is that the loud speaker of two-wire multiple signal transmission in the Public Address system detects the control circuit electrical schematic diagram.
Preferred forms
In order to implement the loud speaker Detection ﹠ Controling of two-wire multiple signal transmission in the Public Address system, 1 or 2 be described further in conjunction with the accompanying drawings, (1) level pressure audio signal band pass filter (1), carrier signal band pass filter (2), dc power signal low pass filter (3), terminal audio frequency signal bandpass filter (4), terminal low pass filter (5), terminal carrier signal band pass filter (6), terminal processes circuit (7), it is characterized in that: the level pressure audio signal is to export by level pressure audio signal band pass filter (1), two-way carrier signal is by carrier signal band pass filter (2) output or input, dc power signal is to export by dc power signal low pass filter (3), the corresponding respectively filter (1) separately of each signal, (2), (3), after its output parallel connection with terminal audio frequency signal bandpass filter (4), terminal low pass filter (5), each input of terminal carrier signal band pass filter (6) links to each other simultaneously, terminal audio frequency signal bandpass filter (4) output audio signal, terminal carrier signal band pass filter (6) receives or the feedback carrier signal, terminal low pass filter (5) output DC source signal, carry out by instruction through terminal processes circuit (7) again, realize transmitting with two-wire system in the Public Address system loudspeaker faults detection and the Push And Release control of many signals.(2) goodbye accompanying drawing 2, and level pressure audio signal band pass filter (1) comprises inductor A, capacitor B; Carrier signal band pass filter (2) comprises carrier wave coupling transformer C, resonant capacitor D; Dc power signal low pass filter (3) comprises choke E; Terminal audio frequency signal bandpass filter (4) comprises audio frequency line transformer F, loud speaker Y; Terminal carrier signal band pass filter (6) comprises carrier wave coupling transformer H, resonant capacitance G; Terminal low pass filter (5) comprises block capacitor I, bridge rectifier J, filtering capacitor K; Terminal processes circuit (7) comprises resistor L, voltage-stabiliser tube M, capacitor N, resistor O, diode P, capacitor Q, field effect transistor R, relay S, diode T, field effect transistor U, resistor V, microprocessor W, quartz crystal X; Its circuit connecting relation is that level pressure audio signal one end of input links to each other with inductor A one end, and the level pressure audio signal other end of input links to each other with capacitor B one end; The carrier signal two ends link to each other with the elementary two ends of carrier wave coupling transformer C respectively; Dc power signal one end of input links to each other with choke E one end, the choke E other end and resonant capacitor D one end, the inductor A other end, carrier wave coupling transformer H is utmost point lower end just, block capacitor I one end exchanges input one end and links to each other simultaneously with bridge rectifier J, C level upper end of the resonant capacitor D other end and carrier wave coupling transformer links to each other, C utmost point lower end of the dc power signal other end and carrier wave coupling transformer, the capacitor B other end, resonant capacitor G one end just links to each other utmost point upper end simultaneously with audio frequency line transformer F, the resonant capacitor G other end just links to each other utmost point upper end with carrier wave coupling transformer H, the first utmost point lower end of audio frequency line transformer F exchanges the input other end with the block capacitor I other end and links to each other simultaneously with bridge rectifier J, bridge rectifier J positive output end and filtering capacitor K one end, H utmost point lower end of carrier wave coupling transformer, resistor L one end, coil one end of diode T negative pole and relay S links to each other simultaneously, F utmost point upper end of audio frequency line transformer and loud speaker Y one end, bridge rectifier J negative output terminal, the filtering capacitor K other end, the source electrode of field effect transistor R, the source electrode of field effect transistor U, resistor O one end, capacitor Q one end, voltage-stabiliser tube M is anodal to link to each other simultaneously with microprocessor W the 8th pin, the resistor L other end links to each other with microprocessor W the 1st pin simultaneously with voltage-stabiliser tube M negative pole, quartz crystal X two ends link to each other with the 3rd pin with microprocessor W the 2nd pin respectively, H utmost point upper end of carrier wave coupling transformer links to each other simultaneously with the drain electrode of capacitor N one end and field effect transistor R, the capacitor N other end links to each other with diode P positive pole simultaneously with the resistor O other end, diode P negative pole links to each other with microprocessor W the 4th pin simultaneously with the capacitor Q other end, the loud speaker Y other end links to each other with resistor V one end simultaneously with switch one end of relay S, F utmost point lower end of the switch other end of relay S and audio frequency line transformer links to each other, the resistor V other end links to each other with microprocessor W the 5th pin, microprocessor W the 7th pin links to each other with the grid of field effect transistor R, microprocessor W the 6th pin links to each other with the grid of field effect transistor U, and the drain electrode of field effect transistor U links to each other with diode T positive pole simultaneously with the other end of relay S coil.(3) audio signal of terminal audio frequency signal bandpass filter (4) output is connected to loud speaker through relay S; The carrier signal that terminal carrier signal band pass filter (6) is received is delivered to microprocessor W after diode P detection; The carrier signal of feedback is delivered to H the utmost point upper end of carrier wave coupling transformer in the terminal carrier wave band pass filter (6) after field effect transistor R amplifies, finish the transmission of its two-way carrier signal; Microprocessor W is connected to loud speaker through resistor V and finishes fault detect; The Push And Release control signal of loud speaker is amplified pusher motor type relay S through field effect transistor U and is finished.(4) audio signal of audio frequency line transformer F output is connected to loud speaker through relay S, and microprocessor W the 6th pin promotes to realize through relay S the Push And Release control of loud speaker after field effect transistor U amplifies by the signal of instruction output; The carrier control signal that is received by H utmost point of carrier wave coupling transformer is coupled through capacitor N, after diode P detection, deliver to microprocessor W the 4th pin again, carried out by instruction by microprocessor W, microprocessor W the 5th pin is finished the fault detect of loud speaker through resistor V under the switch off state of relay S; The carrier signal of feedback is exported by microprocessor W the 7th pin, after amplifying, field effect transistor R delivers to H utmost point upper end of carrier wave coupling transformer, return through resonant capacitor G, resonant capacitor D, carrier wave coupling transformer C by the first utmost point of carrier wave coupling transformer H again, realize two-way carrier signal transmission.(5) carrier signal of carrier control signal and feedback should adopt serial data, and terminal part should adopt and receive back feedback mode earlier.(6) to require be end power consumption type device to the microprocessor W in the terminal processes circuit (7), because the D.C. resistance of lead has tens ofly to hundreds of ohms in thousands of meters transmission lines, is very big to the loss of low-voltage dc power supply.(7) frequency of audio signal should be below 20KHz, and the voltage of audio signal should be below 240V, and the carrier frequency of carrier control signal should be below 300KHz, and DC power supply voltage should be below 36V.
Claims (5)
1. the loud speaker of two-wire multiple signal transmission detects control circuit in the Public Address system, it comprises level pressure audio signal band pass filter (1), carrier signal band pass filter (2), dc power signal low pass filter (3), terminal audio frequency signal bandpass filter (4), terminal low pass filter (5), terminal carrier signal band pass filter (6), terminal processes circuit (7), it is characterized in that: the level pressure audio signal is to export by level pressure audio signal band pass filter (1), two-way carrier signal is by carrier signal band pass filter (2) output or input, dc power signal is to export by dc power signal low pass filter (3), the corresponding respectively filter (1) separately of each signal, (2), (3), after its output parallel connection with terminal audio frequency signal bandpass filter (4), terminal low pass filter (5), each input of terminal carrier signal band pass filter (6) links to each other simultaneously, terminal audio frequency signal bandpass filter (4) output audio signal, terminal carrier signal band pass filter (6) receives or the feedback carrier signal, terminal low pass filter (5) output DC source signal, carry out by instruction through terminal processes circuit (7) again, realize transmitting with two-wire system in the Public Address system loudspeaker faults detection and the Push And Release control of many signals.
2. according to the described detection control circuit of claim 1, it is characterized in that: level pressure audio signal band pass filter (1) comprises inductor A, capacitor B; Carrier signal band pass filter (2) comprises carrier wave coupling transformer C, resonant capacitor D; Dc power signal low pass filter (3) comprises choke E; Terminal audio frequency signal bandpass filter (4) comprises audio frequency line transformer F, loud speaker Y; Terminal carrier signal band pass filter (6) comprises carrier wave coupling transformer H, resonant capacitance G; Terminal low pass filter (5) comprises block capacitor I, bridge rectifier J, filtering capacitor K; Terminal processes circuit (7) comprises resistor L, voltage-stabiliser tube M, capacitor N, resistor O, diode P, capacitor Q, field effect transistor R, relay S, diode T, field effect transistor U, resistor V, microprocessor W, quartz crystal X; Its circuit connecting relation is that level pressure audio signal one end of input links to each other with inductor A one end, and the level pressure audio signal other end of input links to each other with capacitor B one end; The carrier signal two ends link to each other with the elementary two ends of carrier wave coupling transformer C respectively; Dc power signal one end of input links to each other with choke E one end, the choke E other end and resonant capacitor D one end, the inductor A other end, carrier wave coupling transformer H is utmost point lower end just, block capacitor I one end exchanges input one end and links to each other simultaneously with bridge rectifier J, C level upper end of the resonant capacitor D other end and carrier wave coupling transformer links to each other, C utmost point lower end of the dc power signal other end and carrier wave coupling transformer, the capacitor B other end, resonant capacitor G one end just links to each other utmost point upper end simultaneously with audio frequency line transformer F, the resonant capacitor G other end just links to each other utmost point upper end with carrier wave coupling transformer H, the first utmost point lower end of audio frequency line transformer F exchanges the input other end with the block capacitor I other end and links to each other simultaneously with bridge rectifier J, bridge rectifier J positive output end and filtering capacitor K one end, H utmost point lower end of carrier wave coupling transformer, resistor L one end, coil one end of diode T negative pole and relay S links to each other simultaneously, F utmost point upper end of audio frequency line transformer and loud speaker Y one end, bridge rectifier J negative output terminal, the filtering capacitor K other end, the source electrode of field effect transistor R, the source electrode of field effect transistor U, resistor O one end, capacitor Q one end, voltage-stabiliser tube M is anodal to link to each other simultaneously with microprocessor W the 8th pin, the resistor L other end links to each other with microprocessor W the 1st pin simultaneously with voltage-stabiliser tube M negative pole, quartz crystal X two ends link to each other with the 3rd pin with microprocessor W the 2nd pin respectively, H utmost point upper end of carrier wave coupling transformer links to each other simultaneously with the drain electrode of capacitor N one end and field effect transistor R, the capacitor N other end links to each other with diode P positive pole simultaneously with the resistor O other end, diode P negative pole links to each other with microprocessor W the 4th pin simultaneously with the capacitor Q other end, the loud speaker Y other end links to each other with resistor V one end simultaneously with switch one end of relay S, F utmost point lower end of the switch other end of relay S and audio frequency line transformer links to each other, the resistor V other end links to each other with microprocessor W the 5th pin, microprocessor W the 7th pin links to each other with the grid of field effect transistor R, microprocessor W the 6th pin links to each other with the grid of field effect transistor U, and the drain electrode of field effect transistor U links to each other with diode T positive pole simultaneously with the other end of relay S coil.
3. according to the described detection control circuit of claim 1, it is characterized in that: the audio signal of terminal audio frequency signal bandpass filter (4) output is connected to loud speaker through relay S; The carrier signal that terminal carrier signal band pass filter (6) is received is delivered to microprocessor W after diode P detection; The carrier signal of feedback is delivered to H the utmost point upper end of carrier wave coupling transformer in the terminal carrier wave band pass filter (6) after field effect transistor R amplifies, finish the transmission of its two-way carrier signal; Microprocessor W is connected to loud speaker through resistor V and finishes fault detect; The Push And Release control signal of loud speaker is amplified pusher motor type relay S through field effect transistor U and is finished.
4. according to claim 1 or 3 described detection control circuits, it is characterized in that: be meant audio signal, two-way carrier signal, dc power signal with many signals of two-wire system transmission; The two-way carrier signal of transmission is meant that the carrier signal of carrier signal band pass filter (2) output is received by terminal carrier signal band pass filter (6), and the carrier signal of feedback is sent carrier signal band pass filter (2) two ends back to through terminal carrier wave band pass filter (6); Terminal audio frequency signal bandpass filter (4), terminal low pass filter (5), terminal carrier wave band pass filter (6), terminal processes circuit (7) compositing terminal part.
5. according to the described detection control circuit of claim 1, it is characterized in that: in a two-wire system Public Address system, can connect a plurality of or hundreds of terminal parts and loud speaker.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNB200410071943XA CN100547947C (en) | 2004-09-16 | 2004-09-16 | The loud speaker of two-wire multiple signal transmission detects control circuit in the Public Address system |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNB200410071943XA CN100547947C (en) | 2004-09-16 | 2004-09-16 | The loud speaker of two-wire multiple signal transmission detects control circuit in the Public Address system |
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| Publication Number | Publication Date |
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| CN1750420A true CN1750420A (en) | 2006-03-22 |
| CN100547947C CN100547947C (en) | 2009-10-07 |
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| Application Number | Title | Priority Date | Filing Date |
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| CNB200410071943XA Expired - Fee Related CN100547947C (en) | 2004-09-16 | 2004-09-16 | The loud speaker of two-wire multiple signal transmission detects control circuit in the Public Address system |
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Cited By (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102270366A (en) * | 2010-12-31 | 2011-12-07 | 北京谊安医疗系统股份有限公司 | Audible alarm device, method for monitoring audible alarm device and anaesthesia machine |
| CN103299352A (en) * | 2010-10-04 | 2013-09-11 | 诺瓦尔有限责任公司 | Method for operating a public address system |
| CN104393943A (en) * | 2013-11-20 | 2015-03-04 | 广州市保伦电子有限公司 | Emergency voice broadcast evacuation system |
| CN105991335A (en) * | 2015-02-25 | 2016-10-05 | 邵未 | Addressable fault isolation system |
| CN109981145A (en) * | 2019-03-29 | 2019-07-05 | 盈帜科技（常州）有限公司 | Fire broadcast area control system and method |
-
2004
- 2004-09-16 CN CNB200410071943XA patent/CN100547947C/en not_active Expired - Fee Related
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103299352A (en) * | 2010-10-04 | 2013-09-11 | 诺瓦尔有限责任公司 | Method for operating a public address system |
| CN103299352B (en) * | 2010-10-04 | 2015-08-19 | 诺瓦尔有限责任公司 | A kind of method for running voice broadcaster |
| CN102270366A (en) * | 2010-12-31 | 2011-12-07 | 北京谊安医疗系统股份有限公司 | Audible alarm device, method for monitoring audible alarm device and anaesthesia machine |
| CN104393943A (en) * | 2013-11-20 | 2015-03-04 | 广州市保伦电子有限公司 | Emergency voice broadcast evacuation system |
| CN105991335A (en) * | 2015-02-25 | 2016-10-05 | 邵未 | Addressable fault isolation system |
| CN109981145A (en) * | 2019-03-29 | 2019-07-05 | 盈帜科技（常州）有限公司 | Fire broadcast area control system and method |
| CN109981145B (en) * | 2019-03-29 | 2022-04-01 | 盈帜科技（常州）有限公司 | Fire-fighting broadcast area control system and method |
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| Publication number | Publication date |
|---|---|
| CN100547947C (en) | 2009-10-07 |
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