CN1148012C - Method and system for VLF ground-wave broadcast and communication - Google Patents
Method and system for VLF ground-wave broadcast and communicationInfo
- Publication number
- CN1148012C CN1148012C CNB981121276A CN98112127A CN1148012C CN 1148012 C CN1148012 C CN 1148012C CN B981121276 A CNB981121276 A CN B981121276A CN 98112127 A CN98112127 A CN 98112127A CN 1148012 C CN1148012 C CN 1148012C
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Abstract
The present invention relates to a method and a system for VLF ground-wave broadcast communication, wherein the system is composed of a transmission device, an earthing coupling transmission network and a terminal receiving device. The present invention has a signal transmission method that a transmission device generates a VLF carrier of 30 to 300KHz modulated with broadcast communication signals. After transmitted to an earthing coupling transmission network by a feeder and irradiated, the VLF carrier is transmitted to a user receiving device in the form of ground waves and the received VLF carrier is demodulated and restored into broadcast signals by the receiving device. The present invention has the advantages that the broadcast signal transmission is not influenced by day and night or topographic features, the signal is stable and reliable, the transmission covering surface is wide, no dedicated pole or dedicated line is needed, the application range is wide, etc.
Description
Technical field
The invention belongs to the broadcast communication field, be specifically related to a kind of very low frequency terrestrial broadcasting means of communication and system.
Background technology
At present, China rural area broadcast communication mainly adopts wired broadcasting equipment and wireless frequency modulation broadcasting equipment system.Wired broadcasting communication apparatus system must set up special bar special line, and the broadcast communication signal is delivered to the user, is received by user receiving equipment; Plant the networking of wired broadcasting, need expend a large amount of human and material resources, financial resources, set up the expensive hundreds thousand of units of a small towns radio network, and easily by natural force and artificial destruction, outside line maintenance and repair amount is big after the networking, and net easily collapses, overlapping investment networking maintenance, the peasant does not survey heavy burden.Wireless frequency modulation broadcasting equipment system, though have the not advantage of hack lever line saving fund, but the sky wave straight line transmits, easily blocked by Gao Shan Gap paddy, the blind area is many, and the networking coverage rate is low in the mountain area, and the modulation frequency resource is very limited, even also can not all set up FM broadcasting in each small towns village in the plains region, otherwise will seriously disturb mutually.Carrier signal is drawn from transmitter with the transfer wire of two weak points in disclosed patented technology " a kind of method of wired broadcasting and system thereof " (patent No. ZLP11041885), wherein draw back from transmitter for one with regard to direct ground connection, after another root is built on stilts earlier again ground connection or directly and " 0 " line in the power network be connected after ground connection again, utilize the earth soil to constitute the transmission loop, because being connected with " 0 " line in the power network most probably, it brings danger to the transmitting apparatus of this system is safe in utilization, and it utilizes the earth soil to constitute the transmission loop merely, very serious to signal attenuation, cause transmission range very short.
Summary of the invention
The present invention is directed to the prior art above shortcomings, purpose is to propagate the very low frequency terrestrial broadcasting means of communication equipment of broadcast communication signal in the mode of surface wave for the broadcasting of villages (towns) village provides a kind of 30-300KHz of selecting for use very low frequency section.
The objective of the invention is to realize in the following manner:
Transmitting apparatus has modulation the 30-300KHz very low frequency carrier wave of broadcast communication signal, export through power amplification, deliver to the ground connection coupling by feed line and send network, enter safe isolating coupler, by carrying out impedance matching and back its of carrier signal voltage lifting being exported an end send into ground networks I, the other end is sent into transmission antenna, transmission antenna along 10KV high-voltage power line/low-voltage power line is parallel set up certain-length after, signal is sent into grounding electrode network II, thereby between power line network and ground surface, form a very low frequency surface wave channel, the channel of broadcast communication signal by constituting between ground surface and power line network, along ground, form with surface wave is propagated forward, and the terminal receiving equipment will be reduced to the broadcast communication signal by received very low frequency carrier wave demodulation from ground.
For realizing above-mentioned broadcast communication method, the present invention has designed following device systems:
Native system comprises that transmitting apparatus, ground connection coupling send network and terminal receiving equipment three parts.Transmitting apparatus is by frequency synthesizer, low pass filter, audio frequency amplifier, modulator, isolated amplifier, the carrier wave preamplifier, the power preamplifier, power amplifier, power combiner is formed, its annexation is, frequency synthesizer produces the output of 30-300KHz carrier wave and connects low pass filter, low pass filter is exported after removing the high order harmonic component of carrier wave, receive modulator with the audio signal of audio frequency amplifier output again, modulated carrier output after modulators modulate connects isolated amplifier, the ripple preamplifier is carried in isolated amplifier output, receive the power preamplifier again, the preposition output of power amplifier connects power combiner and sends network by the coupling of feed line ground connection again.The ground connection coupling sends network and is made of feed line, safe isolating coupler, transmission antenna, 10KV power line network, grounding electrode network I, grounding electrode network II, its annexation is, the power combiner output of transmitting apparatus connects safe isolating coupler through feed line, one termination of coupler output is gone into grounding electrode network I, the other end inserts transmission antenna, and transmission antenna is along the 10KV power line or low-voltage power line is parallel inserts grounding electrode network II after setting up certain-length.Receiving equipment detects automatic switch by the tuning carrier wave frequency-selecting of antenna, the amplification of high-gain carrier wave, phase shift detection, carrier wave, power amplification, loud speaker constitute, its annexation is: exported after the tuning carrier wave frequency-selecting of antenna by the reception antenna picked up signal, connect the amplification of high-gain carrier wave, phase shift detection, power amplification and loud speaker successively.
Safe isolating coupler adopts hollow skeleton (or magnetic material) and the coiling of high pressure resistant insulation multiply copper conductor to form.Transmission antenna adopts multiply steel aluminium stranded conductor, it sets up length is that 1/2 or all-wave of transmitting apparatus carrier wavelength is long, grounding electrode network I with metal trellis gauze be embedded in apart from 1 meter on the face of land dark below, resistance to earth is less than 4 ohm, grounding electrode network II, use insulated metal lead horizontal mesh layering through water-proofing treatment be embedded in apart from 1 meter on the face of land dark below.The antenna and the ground wire of receiving equipment can be inserted in underground or the water simultaneously, enhancing signal intensity, also can separately antenna be inserted underground, picked up signal, receiving equipment can be with the two merit executive circuits of a kind of very low frequency carrier wave, thereby between the terminal use, realize the safe isolating coupler of phone SCN Space Cable Network, it is exported a termination and goes into the grounding electrode network, the other end sets up behind the certain-length (1/4 along the 10KV high-voltage power line is parallel, 1/2 carrier wavelength or all-wave wavelength), insert grounding electrode network II again, the broadcast communication signal arrives user receiving equipment by the channel that constitutes between ground surface and power line network in the surface wave mode, receiving equipment will be from the face of land or the carrier signal demodulation of underground acquisition be reduced to the broadcast communication signal, and by promoting the loudspeaker broadcast after the power amplification.
As shown in Figure 2, realize above-mentioned broadcast communication method, the present invention has adopted following device systems, and is made up of transmitting apparatus, ground connection transmission network, receiving equipment and power supply.
Transmitting apparatus is made up of frequency synthesizer, low pass filter, audio frequency preamplifier, modulator, isolated amplifier, phase corrector, carrier wave preamplifier, power preamplifier, power amplifier, power combiner as shown in Figure 3.The 30-300KHz very low frequency carrier wave that frequency synthesizer produces, leach high order harmonic component through low pass filter, the output of low pass filter is delivered to modulator with the output of audio frequency preamplifier and is formed modulated carrier, isolated amplifier is sent in modulator output, the carrier wave preamplifier is sent in isolated amplifier output, the power preamplifier is sent in its output behind the phase corrector phase calibration, power amplifier is sent in the preposition amplification output of power, high-power carrier signal through amplifying, power combiner, synthetic high-power carrier signal is sent into the ground connection coupling by feed line and is sent network.
As shown in Figure 4, the ground connection coupling sends network by feed line, safe isolating coupler, and grounding electrode network I, transmission antenna 10KV power line network and grounding electrode network II constitute.Send into safe isolating coupler by the high-power carrier signal that transmitting apparatus is synthetic by feed line, carry out impedance matching and carrier signal voltage promoted the back that it is exported a termination and goes into ground networks I by special coupled modes, the other end insert transmission antenna, transmission antenna along 10KV high-voltage power line (or low-voltage power line) is parallel set up certain-length (1/4,1/2 or all-wave of carrier wavelength is long) after, insert grounding electrode network II.Thereby between power line network and ground surface, form a very low frequency surface wave channel, the broadcast communication signal is delivered to the user.
Terminal use's receiving equipment of accompanying drawing 5, comprise the tuning carrier wave frequency-selecting of antenna, the high-gain carrier wave amplifies, the phase shift detection, carrier wave detects automatic switch, power amplification, loud speaker are by the carrier signal of reception antenna acquisition, through the tuning carrier wave frequency-selecting of antenna, after selecting carrier signal that transmitting apparatus sends and sending into the high-gain carrier wave and amplify, carry out the phase shift detection, detection output send power amplifier to amplify, and promotes loud speaker.Receiving equipment of the present invention also has carrier wave and detects automatic switching circuit, is convenient to realize that broadcasting station, township among the present invention is to the automation control of user's received signal.
Claims (6)
1. the very low frequency terrestrial broadcasting means of communication, it is characterized in that producing the very low frequency carrier wave that modulation has the 30-300KHz of broadcast communication signal by transmitting apparatus, export through power amplification, deliver to the ground connection coupling by feed line and send network, enter safe isolating coupler, by carrying out impedance matching and back its of carrier signal voltage lifting being exported an end send into ground networks I, the other end is sent into transmission antenna, transmission antenna along 10KV high-voltage power line/low-voltage power line is parallel set up certain-length after, signal is sent into grounding electrode network II, thereby between power line network and ground surface, form a very low frequency surface wave channel, the broadcast communication signal propagates into user receiving equipment by the channel that constitutes between ground surface and power line network forward with the form of surface wave, receiving equipment will be from ground or underground received very low frequency carrier wave demodulation be reduced to the broadcast communication signal.
2. realize the system of the described very low frequency terrestrial broadcasting of claim 1 means of communication, it comprises transmitting apparatus, the ground connection coupling sends network and terminal receiving equipment three parts, it is characterized in that transmitting apparatus is by frequency synthesizer, low pass filter, audio frequency amplifier, modulator, isolated amplifier, the carrier wave preamplifier, the power preamplifier, power amplifier, power combiner is formed, its annexation is: frequency synthesizer produces the output of 30-300KHz carrier wave and connects low pass filter, export after the high order harmonic component of low pass filter filters out carrier wave, audio signal with audio frequency amplifier output is received modulator, modulated carrier output after modulators modulate connects isolated amplifier, the ripple preamplifier is carried in isolated amplifier output, receive the power preamplifier again, the output of power preamplifier connects power amplifier successively, power combiner sends network by the coupling of feed line ground connection again; The ground connection coupling sends network and is made of feed line, safe isolating coupler, transmission antenna, 10KV power line network, grounding electrode network I, grounding electrode network II, its annexation is: the power combiner output of transmitting apparatus connects safe isolating coupler through feed line, one termination of safe isolating coupler output is gone into grounding electrode network I, the other end inserts transmission antenna, and transmission antenna is along the 10KV power line or low-voltage power line is parallel inserts grounding electrode network II after setting up certain-length.
3. radio communication system described in claim 2, it is held to levy and is that receiving equipment detects automatic switch by the tuning carrier wave frequency-selecting of antenna, the amplification of high-gain carrier wave, phase shift detection, carrier wave, power amplification, loud speaker, its annexation is: exported after the tuning carrier wave frequency-selecting of antenna by the reception antenna picked up signal, connect the amplification of high-gain carrier wave, phase shift detection, power amplification and loud speaker successively, carrier wave detects the output that automatic switch connects the phase shift detection.
4. the radio communication system described in claim 2 or 3, it is characterized in that safe isolating coupler adopts hollow skeleton or magnetic material and the coiling of high pressure resistant insulation multiply copper conductor to form, transmission antenna adopts multiply steel aluminium stranded conductor, it sets up length is that 1/2 or all-wave of transmitting apparatus carrier wavelength is long, grounding electrode network I with the netted level of naked metal wire be embedded in apart from 1 meter on the face of land dark below, resistance to earth is less than 4 ohm, grounding electrode network II, use insulated metal lead horizontal mesh layering through water-proofing treatment be embedded in apart from 1 meter on the face of land dark below.
5. as radio communication system as described in the claim 3, it is characterized in that the antenna of receiving equipment sagging earthward, antenna and ground wire can insert underground simultaneously or water in, enhancing signal intensity, also can separately antenna be inserted underground, picked up signal.
6. radio communication system as claimed in claim 3 is characterized in that receiving equipment can be with the two merit executive circuits of a kind of very low frequency carrier wave, thereby realize telephonic communication between the terminal use.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNB981121276A CN1148012C (en) | 1998-07-03 | 1998-07-03 | Method and system for VLF ground-wave broadcast and communication |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CNB981121276A CN1148012C (en) | 1998-07-03 | 1998-07-03 | Method and system for VLF ground-wave broadcast and communication |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN1241072A CN1241072A (en) | 2000-01-12 |
| CN1148012C true CN1148012C (en) | 2004-04-28 |
Family
ID=5222006
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CNB981121276A Expired - Fee Related CN1148012C (en) | 1998-07-03 | 1998-07-03 | Method and system for VLF ground-wave broadcast and communication |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN1148012C (en) |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN103334793B (en) * | 2013-07-12 | 2015-06-10 | 河北联合大学 | Underground audio broadcasting alarming device |
-
1998
- 1998-07-03 CN CNB981121276A patent/CN1148012C/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| CN1241072A (en) | 2000-01-12 |
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