VLF ground wave telephone equipment

A kind of telephone equipment, very low frequency technology, applied in the field of communication, can solve the problems of heavy maintenance and repair tasks, many external line faults, interactive interference, etc., and achieve the effect of easy installation and use, avoiding interactive interference, and stable and reliable signals

Inactive Publication Date: 2004-02-18
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AI-Extracted Technical Summary

Problems solved by technology

This kind of wired telephone network construction consumes a lot of manpower, material resources, and financial resources. It costs hundreds of thousands of yuan to build a telephone network in a township. After the network is built, it is easily damaged by natural forces and man-made damage. There are many external line failures and heavy mainten...
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A VLF ground wave telephone equipment in VLF band (20-300 KHz) is composed of user extensions, switch, ground wave telephone power amplifier-transmitter, ground coupled transmitting network and power supply. Said user extensions consist of emitter, receiver and dialing circuit. Said ground coupled transmitting network is composed of feed back line, impedance converter, transmitting antennas, high-voltage (10KV) power transmission line, and grounding electrode networks. Its advantages are developing new frequency resource, high anti-interference power, stable and reliable signals, no blind region in transmission, low cost and high security and compatibility.

Application Domain

Power distribution line transmissionSubstation equipment

Technology Topic

Feed lineTransmission line +13


  • VLF ground wave telephone equipment
  • VLF ground wave telephone equipment
  • VLF ground wave telephone equipment


  • Experimental program(1)

Example Embodiment

[0026] Example: see figure 1 , VLF terrestrial wave telephone equipment, the (own) individual user’s telephone set A lifts the dial, and sends the signal to the ground wave telephone power amplifier transmitter via the switch. The high-power signal output by the power amplifier transmitter is fed The wire is connected to the ground coupling and the transmission network radiates and spreads, and the signal is sent to the (other party) switch by ground wave, and then transferred to the other party's individual user phone B, and the signal from the party is demodulated and restored to voice by the receiving circuit , The other party's individual phone B goes off-hook, and the voice signal is transmitted back to the party in the same manner as described above, and the duplex intercom call is realized between the individual user phones of the two parties.
[0027] Individual user telephone circuit see figure 2 Shown: The output of the voice amplifier is connected to the RF modulator, the output of the RF modulator is connected to the RF amplifiers A and B, and the output of the RF amplifier A and B are connected to the adapter. The front A and B outputs of the reception are connected to the frequency discriminator of the middle amplifier and the middle amplifier The frequency discriminator outputs the receiving voice amplifier, the output of the receiving voice amplifier is connected to the loudspeaker, the signal generator outputs the receiving number judge, and the receiving number judger outputs the receiving voice amplifier. The voice amplifier consists of capacitors C31-C36, resistors R15-R21, diodes V13-V14, microphone S2, and integrated circuit D1E4069. Its working mode is: the voice signal generated by the microphone S2 is coupled to the integrated circuit D1E4069 via C26 to amplify and output, and send it to the radio frequency modulator for radiation. The radio frequency modulator is composed of capacitors C37-C41, resistors R22-R28, potentiometers W1, W2, diodes V16-V19, triode V15, integrated circuits N2 and D2. Its working mode is: voice amplifier output is sent through C28 The integrated circuit N2 modulates the carrier, and the modulated carrier is amplified by the transistor V15, coupled by the resistor R22 and sent to the radio frequency amplifier. The radio frequency transmitting amplifiers A and B are composed of capacitors C1-C6, C13-C18, resistors R1-R4, R7-R10; diodes V3, V4, V9, V10, transistors V1, V2, V7, V8, inductors T1, T2, T7 , T8 composition. Its working mode is that the carrier signal sent by resistor R22 is frequency-selected and amplified by transistors V1, V2, V9, V10, and the amplified carrier signal is coupled to the power amplifier via C89, and receives preamplification A and B, and is amplified by capacitors C6-C12 and C18. -24, resistors R15-R6, R11-R12, diodes V5, V11, transistors V6, V12, integrated circuits D1A, D1B, D1C, D1D, inductors T4, T5, T6, T10, T11, T12. Its working mode is that the carrier signal sent by the other party is coupled to the integrated circuits D1A, D1B, D1C, D1D through C7 and C18 for frequency selective amplification, and the output is connected to the transistor V6 and V12 for re-amplification, and then sent to the mid-amp frequency discriminator through C4 . The intermediate amplifier frequency discriminator is composed of capacitors C42-C54, resistors R29-R39, diode V18, transistor V19, integrated circuit N3, inductors T14 and T15, and intermediate frequency filter J1. Its working mode is to mix, amplify, discriminate, and detect the carrier signal sent by C33, and then restore the voice signal to be coupled to the voice receiver amplifier and receiver decoder judger by R39. The radio voice amplifier is composed of integrated circuit N4A (LM386), speaker S1, resistor R40-46, and capacitor C55-C60. Its working mode is to amplify the voice signal sent by R39 by integrated circuit N4A and send it to speaker S1 through C55. Revert to sound. The number transmitter is composed of capacitors C62-C66, resistors R47-R49, integrated circuit N5 (WE1210), crystal X2, and dial JP. Its working mode is that the dial signal generated by integrated circuit N5 (WE1210) is coupled to N1 (LM567) via C57 for modulation. The receiving number decoding decision device consists of capacitors C67-C82, resistors R50-R79, diodes V26-V34, V36-V38, V40-V46, transistors V24, V25, V35, V39, crystal X3, integrated circuit N6MT8870, D3MC4028, D5A, D5B, D5C, on-hook button K3. Its working mode is that the dual audio signal sent by R39 is decoded by integrated circuits N6MT8870 and D3MC4028, and D5A, D5B, D5C make judgments and control the working state of the whole machine.
[0028] The circuit of the ground wave telephone power amplifier transmitter see image 3 As shown, it is composed of capacitors C1-C17, resistors R1-R22, potentiometers W1-W7, transistors V1-V6, integrated circuits N1A, N1B, N2A, N2B, and power combiner TRANS4. Its working mode is that the carrier signal sent by the telephone switch is amplified by the transistors V1-V6 and the integrated circuits N1 and N2 and then combined with power, and the combined output is sent to the ground coupled transmission network.
[0029] See the circuit of the adapter Figure 4 As shown, there are capacitors C1-C6, resistors R1-R18, diodes V1-V9, transistors V10-V11, integrated circuits U1A-U1D, D1A-D1D, D2A-D2C, D3A, D3C-D3F, N1, relays J1, J2 composition. Its working method is to detect the telephone field strength and decoding decision device sent by the individual user's phone, and the integrated circuits U1A-U1D, D1A-D1D, D2A-D2C, D3A, D3C-D3F, N1 control relays J1, J2 , So as to control the working state of the power amplifier and the on-off of the voice, and realize the transfer.
[0030] Ground-coupled transmission network to see Figure 5 As shown, the signal output by the ground wave telephone power combiner is connected to the impedance converter through the feeder line. The impedance converter is made of magnetic material or hollow material as the skeleton and wound with insulated wires. The two ends of the impedance converter output are respectively connected and sent After the signal antennas A and B, the transmitting antennas A and B are installed in parallel along the 10KV high-voltage power transmission line for a certain distance, the ends are connected to the ground electrode network I and II respectively, and the ground electrode network is buried horizontally at least 1 meter underground with an insulated metal wire mesh. deep.
[0031] The working process of the VLF ground wave telephone equipment of the present invention is as follows: A main call: After the individual user's phone is off-hook, the receiving and decoding judger generates an off-hook blind tone, and the dialed number is sent to the radio frequency modulator through the number transmitter. The modulated 20-300KHz carrier wave is sent to the radio frequency transmitter, the output of the radio frequency transmitter is sent to the ground wave telephone power amplifier transmitter through the adapter, and the high-power carrier signal output by the transmitter is sent to the ground coupling transmission network by the feeder. Signal antenna and ground electrode network. After VLF electromagnetic waves radiate from the signal antenna and ground electrode network, they travel along the ground surface and reach each other in the form of ground waves. When the other party picks up the phone, the voice sent by the party is amplified by the voice amplifier and sent to the frequency modulator and then sent to the radio frequency transmitter, and then sent to the ground wave telephone power amplifier transmitter for amplification by the adaptor. The ground electrode network radiation transmits the other party, and the other party talks to the other party. After receiving the carrier signal of the other party, the receiving circuit sends it to the receiving mid-amp discriminator via the receiving pre-amplifier, and sends the audio signal after the mid-amp discriminator demodulation to the audio amplifier, and then sends it to the speaker after amplification; After receiving the preamplifier to amplify the carrier signal, send it to the IF discriminator. After the IF discriminator, the call code of the other party is demodulated and sent to the receiver decoder and judger. After the demodulation judges that the calling code is consistent, the ring current circuit will flow. The signal is sent to the audio amplifier to amplify and send the speaker to ring, the local party picks up the phone, the ring current circuit closes the signal, the other party makes a call, the other party’s signal is sent to the intermediate amplifier frequency discriminator through the intermediate amplifier frequency discrimination solution The tuned audio signal is sent to the voice amplifier, and the amplified audio signal pushes the speaker to complete the process of being called, so as to realize the dialogue and communication between the two parties.


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Description & Claims & Application Information

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