CN202334688U - Passive isolation communication device of public switched telephone network (PSTN) terminal device - Google Patents

Abstract

The utility model relates to a passive isolation communication device of a public switched telephone network (PSTN) terminal device, which relates to a PSTN. Input ends of a polarity switch circuit, a signal detection circuit and a ringing circuit are respectively connected with a feed signal transmission information protocol and ringing signal output end of the PSTN, an output end of a fixed positive polarity voltage signal formed by the polarity switch circuit is respectively connected with a receiving signal input end of a transmitting/receiving circuit and an input end of a dialing circuit, a transmitting output end of the transmitting/receiving circuit, an output end of the dialing circuit, an output end of the signal detection circuit and a ringing voltage output end of the ringing circuit are respectively connected with an input port of a main controller, an input port of an isolation communication port circuit is connected with the ringing circuit and the main controller, a receiving/transmitting two-wire simulation serial port communication port of the isolation communication port circuit is connected with a main device, and two-wire simulation serial port communication control between the passive isolation communication device of the PSTN terminal device and the main device can be realized.

Description

The passive isolated communication device of a kind of PSTN terminal equipment

Technical field

The utility model relates to a kind of PSTN, especially relates to the passive isolated communication device of a kind of PSTN terminal equipment.

Background technology

Fast development along with electronic technology; The communication technology is also more and more flourishing; In today that communication products rapidly increase; Though mobile communication and network service have occupied sizable market, being based on the traditional communication of fixed telephone network---PSTN (Public Switched Telephone Network is abbreviated as PSTN) communication still also has its indispensable status.At present, still there are a lot of fields all need combine PSTN to realize different communication functions, all relate to PSTN such as traditional communication product, information platform, mediaphone and safety alarm system product etc.

Chinese patent CN 101068238 discloses the call method of a kind of PSTN terminal and instant communication terminal; Comprise: instant communication terminal sends log-on message to instant communication server, and log-on message comprises the identification information and the network address information of said instant communication terminal; Message request is sent to instant communication server through Softswitch in the PSTN terminal, and this message request comprises identification information; Instant communication server sends the instant communication terminal of message request to identification information appointment, and instant communication terminal returns message request to instant communication server; PSTN terminal and instant communication terminal are set up the Media Stream of conversing.Simultaneously, this invention also discloses the call method of a kind of PSTN terminal and instant communication terminal, and the phone system of a kind of PSTN terminal and instant communication terminal.

Summary of the invention

The purpose of the utility model is to provide a kind of PSTN terminal equipment passive isolated communication device.

The utility model is provided with polarity switching, send words/PAC circuit, dial-up circuit, signal deteching circuit, ringing circuit, master controller (MCU), isolated communication interface circuit and power circuit;

The electric feed signal of the external public switched telephone network network of the input of said polarity switching, signal deteching circuit and ringing circuit transmits information protocol (TIP) and bell signal (RING) output; Fixedly positive polarity voltage signal (TTIP) output by polarity switching forms is met and sent off the accepted call signal input of words/PAC circuit, the input of dial-up circuit respectively; Send words output, the output of dial-up circuit, the output of signal deteching circuit, the ringing voltage output of ringing circuit of words/PAC circuit to connect the input port of master controller (MCU) respectively; The input interface of isolated communication interface circuit is connected with master controller (MCU) with ringing circuit; Reception/transmission (RX/TX) 2 line simulative serial port communication interfaces of isolated communication interface circuit connect main equipment, and passive isolated communication device of PSTN terminal equipment and main equipment are realized 2 line simulative serial port Control on Communication.

Said polarity switching can be made up of the rectifier bridge heap.

The 48V electric feed signal that the electric feed signal transmission information protocol (TIP) of said public switched telephone network network and bell signal (RING) are generally the public switched telephone network network transmits information protocol (TIP) and bell signal (RING).

Generally speaking, communicating by letter between PSTN communication module and the main equipment all adopted the optical coupling isolation technology.But two end systems of implement isolating at needs all must the external power supply power supply, and promptly PSTN communication module and main equipment all need the purpose that electric power system independently just can reach isolated communication separately.Yet the power-supply system of PSTN circuit is easy to receive the interference of external power source system and introduces noise, if the performance of external power supply is bad, also can causes the short circuit of telephone line feed under the serious situation and can not use.Therefore in the PSTN line system external power-supply system is required very highly, obviously increased the technical difficulty and the cost of system.

The maximum characteristics of the utility model are under receiver-on-hook condition; The energy that makes full use of ringing signal generating signal to be MCU and optocoupler power supply; Cooperation through software and hardware; Do not need external power supply just can use optical coupling isolated communication technology at PSTN line system end, realize the passive isolated communication between PSTN line system end and the main equipment well.And send the collection of information such as the incoming information of PSTN, ringing information to main equipment.Adopt the passive isolated communication mode of this dispense with outer connecting power, strengthened the antijamming capability and the isolation effect of system significantly; Also greatly reduce simultaneously the cost of system product, strengthened competition capability.

Description of drawings

Fig. 1 is the structure composition frame chart of the utility model embodiment.

Fig. 2 is that the wireline inspection circuit of the utility model embodiment is formed schematic diagram.

Fig. 3 send words/PAC circuit theory of constitution figure for the utility model embodiment's.

Fig. 4 is the standby power-supply circuit theory of constitution figure of the utility model embodiment.

Fig. 5 is that input and the MCU circuit of the utility model embodiment formed schematic diagram.

Fig. 6 is the ring power taking power circuit theory of constitution figure of the utility model embodiment.

Fig. 7 is the ring power taking power supply wave shape sketch map of the utility model embodiment.

Fig. 8 is isolated communication and the power circuit theory of constitution figure of the utility model embodiment.

Fig. 9 is the power supply wave shape sketch map of the isolated communication of the utility model embodiment.

Figure 10 is that the common PSTN isolated communication circuit of the utility model embodiment is formed schematic diagram.

Figure 11 is the main program flow chart of the utility model embodiment.

Embodiment

As shown in Figure 1, the utility model embodiment is provided with polarity switching 1, send words/PAC circuit 2, dial-up circuit 3, signal deteching circuit 4, ringing circuit 5, master controller (MCU) 6, isolated communication interface circuit 7 and power circuit 8;

The 48V electric feed signal TIP and the RING output of the external public switched telephone network network of input of said polarity switching 1, signal deteching circuit 4 and ringing circuit 5; Fixedly positive polarity voltage signal TTIP output by polarity switching 1 forms is met and sent off the accepted call signal input of words/PAC circuit 2, the input of dial-up circuit 3 respectively; Send words output, the output of dial-up circuit 3, the output of signal deteching circuit 4, the ringing voltage output of ringing circuit 5 of words/PAC circuit 2 to connect the input port of master controller (MCU) 6 respectively; The input interface of isolated communication interface circuit 7 is connected with master controller (MCU) 6 with ringing circuit 5; The RX/TX2 line simulative serial port communication interface of isolated communication interface circuit 7 meets main equipment A, and passive isolated communication device of PSTN terminal equipment and main equipment A realize 2 line simulative serial port Control on Communication.

Said polarity switching 1 can be made up of the rectifier bridge heap.

The concrete operation principle circuit of the utility model embodiment is shown in Fig. 2～5, and 48V electric feed signal TIP, the RING input sent here from PSTN form a fixedly voltage signal TTIP of positive polarity by the polarity switching that BR1 rectifier bridge heap MB6S forms; Triode Q2 (2SA44), Q3 (2SA94) and Q4 (2SA94) form the load loop switch, the opening and closing of the LOOP dislodging machine signal controlling circuit load loop through IC 1 (HT95A20P) MCU output; Triode Q13 (C9014), Q17 (S8550), Q11 (C9014), Q12 (C9014) and resistance R 48 (18 Ω), R49 (56 Ω), R49 (270 Ω) and voltage stabilizing didoe Z3 compositions such as (4.7V) send words and PAC circuit; Realizing the reception and the transmission of voice, also is the main DC load of whole loop; Q6 (S8050), resistance R 23 (100 Ω), R24 (3.9K Ω), C6 (0.01 μ F) form dial-up circuit with the inner Dual Tone Multifrequency generator of MCU (HT95A20P), and the dtmf signal that produces MCU sends on the circuit; The capacitor C L4 of two 0.01 μ F/250V, CL5 receive the AC signal on the direct join coupling circuit on the feeder line; By triode Q20, Q21 (C9014; The β value is between 400～500) with and peripheral resistance capacitance form the line signal testing circuit; Be responsible for the pulse signal that becomes MCU to discern to conversion of signals such as the frequency shift keying/dual-tone multifrequency on the circuit (FSK/DTMF) incoming telephone signal, dialing tone, ring-back tone, busy tones, by the software identification of decoding; Bell flowing detecting circuit is made up of electric capacity E8, E16 and rectifier bridge heap BR2 (MB6S), 27V voltage stabilizing didoe Z2, filter capacitor E3 (22 μ F/35V) and divider resistance R19 (560K Ω), R20 (100K Ω) and the diode D10 (1N4148) etc. of 1 μ F/250V; The AC signalling signal is separated straight through electric capacity E8, E16; Produce a ringing voltage V_RING after BR2, E3, Z2 rectifying and wave-filtering and the voltage stabilizing, give MCU by R19, R20 dividing potential drop again and detect pin.Wherein C19 is an anti-interference capacitor, and D10 is a clamping diode, the I/O of protection MCU; Wherein triode Q22 (C9014), Q23 (MMBT5551), Q24 (MMBT5401), resistance R 90 (10K Ω), R91 (5.1M Ω), R96 (1M Ω), R89 (120K Ω) etc. form the power circuit of power taking under the holding state; The power circuit of power taking when resistance R 61 (39 Ω), 5.0V voltage stabilizing didoe Z7, electric capacity E2 (220 μ F/10V) and D12 (1N4148) etc. form the incoming call ring; The circuit that Q22 under the loop closed condition～24 and outside capacitance-resistance thereof are formed is MCU and testing circuit power supply, and R61, Z7, E2 and D12 are MCU and the buffer circuit of communicating by letter power supply when ring.MCU passes through TxD_PSTN and RxD_PSTN port and TLP521 photoelectrical coupler U1, U2 and forms the isolated communication circuit, realizes the control of 2 line serial communications with main control device.

At ordinary times feed voltage is direct current 48V on the PSTN circuit, and promptly the voltage when line terminal equipment does not have off-hook work is direct current 48V.When the customer call terminal equipment, when the incoming call ring is promptly arranged, switch will send bell signal on the telephone BORSHT functions circuit, and bell signal is for exchanging 75V ± 15V, 25Hz ± 3Hz, and is every at a distance from the 5s one-period, and promptly signal 1s is logical, 4s is disconnected.The utility model is received on the feeder line as the terminal equipment of PSTN circuit, and MCU is operated in sleep state at ordinary times, and its power consumption stream is in 10uA, and integral body meets the related request of automatic telephone technical conditions GB GB/T 15279-2002.When the utility model need communicate with main equipment, the necessary full speed running of MCU got into high power consumption state, and at this moment therefore operating current, can not directly adopt feed to supply power greater than 2mA.But the utility model when incoming call, must be transferred to main control device to incoming information under receiver-on-hook condition.So; Realize isolated communication like dispense with outer connecting power; Then can utilize the characteristic of circuit bell signal---during ring on the circuit each ringing cycle an AC signal that to continue one second amplitude be 75V ± 15V all can be arranged, so the electric power system of the utility model just can make full use of this bell signal and obtains additional power supply.The concrete principle circuit theory as shown in Figure 6 that realizes; When on the circuit bell signal being arranged; Bell signal is through partiting dc capacitor E8, E16; Then through the full-wave rectification of BR2 bridge heap, can obtain pulsation output voltage V _ RING of a 27V again after smoothly through the voltage stabilizing of 27V voltage-stabiliser tube Z2 and E3 filter capacitor (wherein E3 has the accumulation of energy effect concurrently), as shown in Figure 7.

As shown in Figure 8, after the output ripple voltage V_RING of this about 27V passes through the current limiting pressure-limiting and E2 filtering of R61, Z7 (5V voltage stabilizing didoe) again, just can obtain as shown in Figure 9 one the VCC voltage of the highest pact+5V supply with MCU and optocoupler work.

Adopt the MCU and the optocoupler of the wide voltage of low-power consumption in the utility model, its operating voltage range is wide ,+2.5V～+ can both keep operate as normal in the scope of 5.5V.When Vcc rise to+during 3V; Luminescent device makes the sensor devices operate as normal with regard to obtaining enough electric currents among the optocoupler U1; Thereby MCU just can give main control device the data correct transmission that needs are uploaded, and can receive information and the order that main control device passes down through U2.What data message amount that the utility model need transmit was maximum is incoming information, and 30 characters are arranged approximately, needs about 210ms with its call duration time of baud rate of 1200bps.Time at the t1～t2 shown in Fig. 9 is about 400ms, therefore t1～t2 in this time period enough the utility model accomplish the exchanges data with main equipment.This module makes full use of the energy of this short time of bell signal and not needing to realize external power supply to carry out the optical coupling isolated communication.

The maximum characteristics of the utility model are the optical coupling isolated communication technology that has adopted to a kind of PSTN side dispense with outer connecting power of PSTN circuit original creation; Promptly PSTN communication module dispense with outer connecting power just can be realized the collection of the information such as incoming information, ringing information of PSTN under receiver-on-hook condition, and is transferred to main equipment through the isolated communication mode.

Generally speaking, when adopting the optical coupling isolated communication, two end systems of implementing to isolate at needs all must the external power supply power supply, and shown in Figure 10 structured flowchart, need connect also in the PSTN system side that external power adapter 9 comes is MCU and optical coupler power supply.In Figure 10, other mark is identical with Fig. 1.

Yet PSTN line power system is easy to receive the interference of external power source system and introduces noise, if isolating coldly and thermally of external power supply is bad, also can causes the short circuit of telephone line feed under the serious situation and can not use.Therefore in the PSTN line system external power-supply system is required very highly, increased the technical difficulty and the cost of system virtually.And the PSTN line system is very strict to the feed leakage current requirement of itself; Requirement according to automatic telephone technical conditions GB GB/T 15279-2002; The feed leakage current of terminal equipment under hook state can not be greater than 25 μ A, and the PSTN communication module is communicating in the process with main equipment, and its operating current is greater than 2mA; Therefore under hook state, can not directly adopt the feed communication of supplying power, otherwise the appearance lost line of sending a telegram here easily.To these problems; The utility model adopts principle noted earlier; The energy that makes full use of ringing signal generating signal to be MCU and optocoupler power supply; Through the cooperation of software and hardware, do not need external power supply just can use optical coupler isolated communication technology at PSTN line system end, realize the passive isolated communication between PSTN line system end and the main equipment well.Adopt the passive isolated communication mode of this dispense with outer connecting power, strengthened the antijamming capability and the isolation effect of system significantly; Also greatly reduce simultaneously the cost of system product, strengthened competition capability.

The utlity model has following function:

1) the plucking of telephone set, on-hook: after the utility model receives the off-hook instruction that main equipment sends here, then can connect the feed loop, i.e. off-hook.After the utility model receives the on-hook instruction that main equipment sends here, then can break off the feed loop i.e. on-hook.

2) handle, hands-free off-hook switch: when the utility model is under the handle off hook state, as receive the hands-free off-hook order that main equipment is sent before detecting handle HOOK_ON state, then can become the hand-free call state.

3) dialing: after the utility model receives the dialing instruction and dial content that main equipment sends here, can produce into dtmf signal to the dial content that receives and deliver to feeder line.

4) dodge disconnected: under the state of off-hook, after the utility model receives the sudden strain of a muscle severed finger order that main equipment sends, can be according to the sudden strain of a muscle break time that receives, like 100ms, the on-hook of 600ms elder generation, and then off-hook.

5) redial: when the utility model receive that main equipment sends redial instruction after, can dial the telephone number of dialing for the last time once again.

6) conversation: the utility model itself has voice loop call function, can incoming call answering.

7) line mute: after the utility model receives the quiet instruction that main equipment sends, can send words to stop to send to circuit current according to quiet command content, the voice of perhaps sending current circuit here carry out the quiet microphone of not delivering to.

8) DTMF and the FSK double-standard soft decoding of sending a telegram here: when sending electrical information here on the circuit, the utility model can judge and receive DTMF or FSK standard incoming information, and carries out the data message decoding according to different incoming call standards, and active upload is given main equipment then.

9) line status detects: the utility model can detect the connection status (have is connected or breaks off with feeder line) of current and circuit, and when wire connection state changed, the ability active be uploaded to main equipment to current connection status.

10) ringing-current detects: when circuit had incoming call, the utility model can detect bell signal, and initiatively was uploaded to main equipment to bell signal, and etc. pending main equipment to the process information of this incoming call.

11) the circuit anti-polar signal detects: when the polarity reversing signal of generation was arranged on the circuit, the utility model can detect and active upload gives main equipment to make corresponding processing, such as getting into the telephoometry state or starting billing function etc.

12) the line signal sound detects: under off hook state, and dialing tone, ring-back tone, voice, type busy tone and busy-back signal on the utility model ability detection line, and active upload is handled to main equipment.

13) simulative serial port communication: the utlity model has the simulative serial port communication interface of 2 lines (RX/TX), can realize various functions through serial communication with main equipment.

14) isolated communication: have the isolated communication function between the utility model and the main equipment, dispense with outer connecting power is realized the serial ports isolated communication under hook state, avoids external power supply and main equipment through the utility model the PSTN circuit to be produced and disturbs.

Below provide the interface definition of the utility model:

1, adopt 2 lines (RX/TX) serial communication protocol, the serial ports parameter is referring to table 1

Table 1

Baud rate	?1200bps
		Start bit	?1Bit
Position of rest	?1Bit
		Data bit	?8Bit
Odd-even check	Do not have
		RTS/CTS	Do not have

2, the communications command formal definition is following:

Frame head (0xAA)+length (length)+type (type)+data (data)+bag sequence number+check code+end mark (0x0D)

(1) frame head: all packets begin with frame head (0xAA).

(2) length: length+1 of data (data).

(3) type: 1 byte, see the back for details and describe.

(4) bag sequence number: 1 byte, new data packets of every transmission adds 1, makes zero greater than 255, if the bag sequence number is identical with last bag sequence number, shows that this bag is a retransmitted packet.

(5) check code: check code is result's (1 byte) of all byte XORs of front.

(6) end mark: all packets finish with 0x0D.

3, retransmission mechanism explanation:

(1) every bag data are 32 bytes to the maximum.

(2) transmit leg needs to wait for that the recipient returns accepting state after sending data, if reception is correct, can send new data packets, does not receive return information if receive in mistake or the 150ms, needs to retransmit maximum 3 times.

When (3) main equipment sends data, need to send earlier to be ready for sending RTS (ready to send) request signal, can send packet behind the wait phone module response clear to send CTS (clear to send).

The main program block diagram of the utility model is referring to Figure 11.

The utility model is based on traditional PSTN circuit; Employing has strong, low in energy consumption and the specialized application with Reduced Instruction Set Computer RISC (reduced-instruction-set computer) chip architecture of antijamming capability in the MCU of the PSTN communications field, and a kind of PSTN isolated communication module is provided.This module is widely used in traditional communication product, information platform, multimedia communication product and the safety alarm system product that needs combine PSTN.

Claims (3)

1. passive isolated communication device of PSTN terminal equipment is characterized in that being provided with polarity switching, send words/PAC circuit, dial-up circuit, signal deteching circuit, ringing circuit, master controller, isolated communication interface circuit and power circuit;

The electric feed signal of the external public switched telephone network network of the input of said polarity switching, signal deteching circuit and ringing circuit transmits information protocol and bell signal output; Fixedly positive polarity voltage signal output part by polarity switching forms is met and sent off the accepted call signal input of words/PAC circuit, the input of dial-up circuit respectively; Send words output, the output of dial-up circuit, the output of signal deteching circuit, the ringing voltage output of ringing circuit of words/PAC circuit to connect the input port of master controller respectively; The input interface of isolated communication interface circuit is connected with master controller with ringing circuit; The reception of isolated communication interface circuit/transmission 2 line simulative serial port communication interfaces connect main equipment, and passive isolated communication device of PSTN terminal equipment and main equipment are realized 2 line simulative serial port Control on Communication.

2. the passive isolated communication device of a kind of PSTN terminal equipment as claimed in claim 1 is characterized in that said polarity switching is made up of rectifier bridge heap.

3. the passive isolated communication device of a kind of PSTN terminal equipment as claimed in claim 1 is characterized in that the electric feed signal transmission information protocol of said public switched telephone network network and the 48V electric feed signal that bell signal is the public switched telephone network network transmit information protocol and bell signal.

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