215 results about "FM broadcasting" patented technology

A media broadcast and distribution system is disclosed which substitutes storage for communications, allowing more efficient use of scarce bandwidth resources. One embodiment allows a terrestrial FM broadcaster to offer a larger number of higher quality audio channels than current satellite radio services such as Sirius and XM Satellite Radio. This embodiment also has features that offer a better user experience than with personal audio devices such as Apple's iPod™. Another embodiment allows satellite radio services to expand their video offerings.

The invention provides methods for sending and receiving a digital audio signal in a digital audio broadcasting system. Service data are scrambled and subjected to low density parity check (LDPC) coding, constellation mapping and sub-carrier interleaving at a sending end; service description information is scrambled and subjected to convolutional coding, bit interleaving and constellation mapping; system information is subjected to convolutional coding, bit interleaving and constellation mapping; the information and discrete pilots are multiplexed together and mapped to a corresponding spectrum mode to form an orthogonal frequency division multiplexing (OFDM) frequency domain symbol; and conversion of a frequency domain and a time domain is performed, a logic layer frame structure is formed by connection, and a physical layer frame structure is mapped from the logic layer frame structure and framed for transmission. The invention has the advantages that according to the spectrum characteristics of the conventional frequency modulation (FM) frequency range, a flexible spectrum mode is designed, and the conventional analog FM broadcasting signal is not influenced. The invention is expandable in spectrum, flexible in system transmission parameter setting and applicable to single-frequency network and multi-frequency network modes.

The invention relates to a method and a system for receiving digital broadcasting signals in frequency modulation (FM) broadcast bands. The method comprises the following steps of: receiving digital / analog (D / A) mixed signals x (t); preliminarily separating to acquire preliminarily recovered analog FM signals x0FM (t) and digital FM signals d0 (t); performing first level pilot frequency-based iterative separation on the signals to acquire digital and analog FM signals after the first level iterative separation; and performing second level iterative separation by means of pilot frequency and internal codes, wherein the digital FM signals after the iterative separation acquire digital audio signals and data signals through channel decoding, and the analog FM signals acquire analog audio signals through demodulation and D / A conversion. A digital FM signal demodulation decoder of the system comprises a preliminary FM separator, an iterative FM separator, and a synchronization recovery and channel equalizer and a decoding module, and the iterative offset separation of the analog master FM from digital signals is realized. According to the method and the system, the mixed D / A signals overlapped by the same channel are separated, the mutual interference of the signals is eliminated, and the FM band digital broadcasting system can be realized.

The invention relates to a multi-port regional gridding VRS (Virtual Reference Station) differential positioning information broadcasting device and a work method thereof, belonging to the field of measuring methods. The multi-port regional gridding VRS differential positioning information broadcasting device comprises a network RTK (Real Time Kinematic) system reference station, a data processing center and a data FM (Frequency Modulation) broadcasting unit, wherein the network RTK system reference station is connected with a data processing center server through optical fiber, and the data processing center server is connected with the data FM broadcasting unit through a serial port; and the data FM broadcasting unit is used for carrying out FM broadcasting on differential correction data packaged by a UDP (User Datagram Protocol). The work method comprises the steps of: receiving network RTK system reference station information by the data processing center, and dividing grids for the covered region of the network RTK system reference station; then solving all differential correction information of all grid virtual reference stations by utilizing a VRS algorithm, and then appointing an unique UDP port number for each grid virtual reference station and packaging the differential correction information by using the UDP protocol; finally, carrying out FM broadcasting on the UDP data packets, three-dimensional coordinates and UDP port numbers of all the grid virtual reference stations through the data FM broadcasting unit.

The invention discloses a frequency modulation broadcast receiving method and a frequency modulation broadcast receiving terminal. The frequency modulation broadcast receiving method comprises the following steps of: determining the position information of the position of the frequency modulation broadcast receiving terminal; determining the area information of the position according to the position information; determining a radio station list corresponding to the area information; displaying the determined radio station list; and listening to a radio station selected from the determined radio station list. In the frequency modulation broadcast receiving method, the real-time updated radio station list is provided so as to improve the frequency modulation broadcast receiving flexibility; and when the area of the frequency modulation broadcast receiving terminal is switched, the frequency modulation broadcast receiving terminal can conveniently finish switching and receiving frequency modulation broadcast signals in a new area by the real-time updated radio station list in a relatively shorter time.

The invention discloses a method for distributing a file based on an RDS unidirectional broadcast channel and is directed to the field of wireless communication technology. The method is realized (reference image 1) through a system composed of a client, a server and a transmitting station and is characterized in that the server conducts block division, compression, encryption and verification towards the file and sends a distribution data unit to the transmitting station for broadcasting; the client acquires service authorization from the server through a bidirectional channel; the authorized client receives broadcast information, decrypts the data unit received and assembles and decompress the file; the sever ensures that the client receives the complete file through a cycle redundancy broadcast; the client uses .part to record the situation of file reception which is used for breakpoint continuous transmission. According to the invention, the function of file distribution is realized by using the frequency modulation broadcast radio station facility and RDS unidirectional data broadcast channel in the prior art.

The invention provides a frequency modulation (FM) broadcast-based terminal positioning method, which can overcome the defect of the conventional mobile positioning technology and is low in cost, stable and reliable, and high in precision and cruising capability. The method comprises the following steps that: 1, a positioning device sequentially receives broadcast signals at all frequency points in the frequency band specified by FM broadcast, and records the frequency points receiving the broadcast and signal reception strength values so as to obtain a group of broadcast signal strength values transmitted by a plurality of broadcast transmitting stations; 2, the positioning device obtains the geographical positions and the transmitting power information of the broadcast transmitting stations received by the recorded frequency points through the group of broadcast signal strength values which are transmitted by the plurality of broadcast transmitting stations and obtained in the step 1; and 3, the positioning device calculates the position of the terminal to be tested according to the broadcast reception strength values of the frequency points, the FM broadcast frequency, the transmitting power information and the geographical positions of the broadcast transmitting stations. The invention also provides a special positioning device, which comprises a processor unit, an FM broadcast reception module and a storage module, wherein the processor unit and the FM broadcast reception module as well as the storage module are respectively electrically connected through a bus.

The invention provides a separation method and receiving device of a digital broadcasting analog-to-digital (A / D) signal at a frequency modulation (FM) broadcast band. The separation method comprises the following steps: adding two neighboring vector signals in in-band-on-channel (IBOC) A / D mixed signals S, eliminating component of a digital signal dm to obtain x<2m>+x<2m>+1, and then obtaining amplitude and phase, wherein, the nth component of x<2m> and x<2m>+1 can be those of phase modulation signals ej alpha and ej beta; solving parameters theta and delta to obtain x<2m> and x<2m>+1; and restoring the digital signal dm. In the method, the designed antenna of the receiving device is sequentially connected with a tuning module, an A / D converter, a digital down converter (DDC) and a re-sampling module; output of the re-sampling module is switched in an A / D signal separation module with a concrete calculation program to obtain corresponding analog FM signals and digital signals; the signals are respectively accessed to a digital signal demodulator / decoder of an analog FM receiver; and finally an analog sound signal, a digital audio signal and a data signal which are sent from a sending end are obtained finally. The separation method has the advantages of good A / D signal separation effect, capability of eliminating mutual interferences and reliable performance and is easy to achieve.

The present invention discloses a method to realize vehicle-mounted calls, which arranges a FM transmission module into a mobile phone and sets vehicle mode of the mobile phone. While the mobile phone enters into the vehicle mode, a FM transmission loop is started. An audio loop is switched into the FM transmission loop. The FM transmission module transmits audio signals of specified frequency to a FM broadcasting device. And then, the FM broadcasting device receives the audio signal in a corresponding band and broadcasts the signal through a vehicle-mounted acoustic system. Moreover, the present invention discloses a device to realize the method. The method and the device make it unnecessary for users to directly answer the mobile phone and configure other special vehicle-mounted devices. Furthermore, the method and the device are not restricted by mobile phone manufacturers and need lower cost.

The invention belongs to the field of outer transmitter-based radars, and relates to an outer transmitter-based radar system based on multi-FM broadcasting and a detection method. The outer transmitter-based radar system based on the multi-FM broadcasting comprises receiving antennas connected in sequence, a simulation case containing a signal simulating and receiving module, a CPCI case containing a signal collecting and processing module, at least one disk array case containing a signal storage module, a switch and a signal processing machine carrying out signal processing. A multi-FM broadcasting irradiation source adopted by the system has multi-frequency, multi-station and multi-polarization characteristics, a multi-polarization mode is adopted by the receiving antennas, a radio frequency direct sampling structure is adopted for simulating and receiving, a radio frequency band-pass sampling and digital downconversion scheme is adopted by data collection, a high-speed disk array is adopted for data storing, the signal processing machine completes clutter rejection, mutual fuzzy function operation, peak value detection, constant false alarm rate detection, locating and tracking, data fusion and other operations, and finally object distance, speed and azimuth information is output. The outer transmitter-based radar system based on the multi-FM broadcasting and the detection method have the advantages of being free of electromagnetic pollution, resistant to stealth, and high in detection stability and tracking continuity.

The invention relates to a real-time traffic information distribution system, belonging to the road traffic information collection, processing and distribution field of an intelligent traffic system. The real-time traffic information distribution system based on frequency modulation broadcast comprises an information center, an operator network, an information board and a vehicle-mounted radio, wherein, the information center converts the collected traffic abnormal information into an audio signal for broadcasting and sends the information to the information board arranged at the upstream of a congestion section through the operator network; the information board receives a control signal, a yellow flashlight arranged on the information board twinkles and the congestion information is sent to a user within a certain range in the form of frequency modulation broadcast; and a driver can be prompted by the yellow flashlight on the information board and receives the real-time traffic information of a downstream section by the vehicle-mounted radio.

Between a mixer and an intermediate frequency amplifying circuit, there are an intermediate frequency tuning circuit which, for reception of a TV signal, is tuned between a chrominance subcarrier frequency and a video intermediate frequency in an intermediate frequency band, and for reception of an FM broadcasting signal, is tuned nearly to the chrominance subcarrier frequency, and a first trap circuit which attenuates a sound intermediate frequency of an adjacent channel. Next to the intermediate frequency amplifying circuit, there is a second trap circuit which, for reception of a TV signal, brings about attenuation between the video intermediate frequency in the intermediate frequency band and the sound intermediate frequency of the adjacent channel and, for reception of an FM broadcasting signal, brings about attenuation around the video intermediate frequency.

The invention relates to the field of FM broadcasting external radiation source radar and particularly relates to an external illuminators radar false targets supression method based on sub-peak identification and equipment. The method comprises the steps of, calculating a mutual ambiguity function of a reference signal and a monitor signal after clutter suppression and conducting constant false alarm rate detection to acquire suspected targets information; then according to a sub-peak property, detecting respectively and eliminating the false targets triggered by the sub-peak of the same range cell and the same Doppler cell to acquire real targets information. According to the method, the calculated amount of the system can be reduced and the detection property can be improved in the condition of not calculating the mutual ambiguity function of the reference signal and detecting simply and effectively and eliminating false targets triggered by the sub-peak according to the sub-peak property.

The invention discloses a method for navigation positioning by use of digital frequency modulation broadcasting and belongs to the field of wireless navigation. The method comprises the following steps: realizing time synchronization among frequency modulation broadcast transmitters; the frequency modulation broadcast transmitters carrying wireless signals RF(t) whose navigation messages can be used for range finding; the frequency modulation broadcast receivers receiving wireless signals RF(t) broadcast by the multiple frequency modulation broadcast transmitters and parsing the navigation messages contained in the RF (t); and the frequency modulation broadcast transmitters using the navigation messages and the signals of themselves to perform positioning solution so as to obtain positions of themselves. Compared to the prior art, the method provided by the invention has the following advantages: the emission power of the frequency modulation broadcast transmitters is large, the indoor coverage capability is higher compared to space-based navigation and space-based navigation enhancement technologies; and the frequency modulation broadcasting bandwidth is small, and the receiver complexity is low, therefore, the cost is lower and the popularization is easier.

The invention provides an earphone charging device having sound and FM broadcasting functions. The earphone charging device comprises a shell, a main control circuit, a power supply management module, a rechargeable battery, an earphone charging module, a music playing control panel, a music playing module, a loudspeaker horn, a card reader module, a FM module, a radio-frequency module, a parameter detection module and an external power supply charged in a wired or wireless manner; the earphone charging device further comprises a shell; a FM antenna connected with the FM module is arranged on the shell; an earphone is arranged in the middle part of the shell, and contained through an openable box body window cover; a loudspeaker horn sound output hole is arranged on the shell; a charging indication lamp electrically connected with the parameter detection module is also arranged on the shell; therefore, the outward sound playing function of the earphone charging device is realized; three-in-one equipment integrating earphone charging and containing, the outward playing function and FM broadcast listening is provided for users; the outdoor travel convenience and entertainment are improved; and the synchronism and unified management of music libraries can be realized.

The invention discloses an adaptive broadcasting station searching device, an adaptive broadcasting station searching method and an FM receiver; wherein the adaptive broadcasting station searching device, the adaptive broadcasting station searching method and the FM receiver belong to the technical field of automatic broadcasting station searching. The adaptive broadcasting station searching device comprises a scanning unit; a threshold setting unit which is connected with the scanning unit; a storage unit which is connected with the threshold setting unit; a broadcasting station searching unit which is connected with the storage unit; and a recording unit which is connected with the broadcasting station searching unit. The adaptive broadcasting station searching method comprises the steps of firstly performing envelope detection on receiving signal strengths of all frequency points of a full frequency band, and adding a preset demodulation threshold on a detected envelope number, thereby forming a broadcasting station threshold which corresponds with each frequency point; afterwards beginning an FM broadcasting station searching process, and for each searched frequency point, determining whether the receiving signal strength is larger than the corresponding broadcasting station threshold, and determining whether the pilot frequency energy is larger than a preset standard pilot frequency energy; and recording the frequency points which satisfy the two conditions. The adaptive broadcasting station searching device, the adaptive broadcasting station searching method and the FM receiver have a beneficial effect of preventing a problem that some false broadcasting stations and pseudo broadcasting stations are mistakenly considered as true broadcasting stations caused by fixed broadcasting station searching threshold.

A frequency modulation broadcast receiving method for vehicle end comprises determining a geographical position of the vehicle end to determine a current location area of the vehicle end; acquiring, based on the current location area, a local broadcasting radio station list which is corresponding to the current location area and is stored in the vehicle end; if the local broadcasting radio station list is not acquired in the vehicle end, automatically acquiring the local broadcasting radio station list according to radio station radio wave of the current local area and storing the local broadcasting radio station list, and when the vehicle end arrives at the current local area again, retrieving the stored local broadcasting radio station list; and based on the local broadcasting radio station list, determining which radio station is to be selected and playing the selected radio station. When a vehicle end enters a new area, the local broadcasting radio station list that is corresponding to the current location area of the vehicle end and is stored in the vehicle end is retrieved by the vehicle end, and thus a broadcasting radio station searching process is saved, a radio station is selected and determined in a relatively short period, and user experience of the vehicle end is improved.

The invention discloses a software wireless technology-based heterogeneous network experimental device. The device faces a wireless sensor network, a wireless local area network, a frequency modulation broadcast network and the Internet. Experimental equipment comprises universal gateway nodes, wireless sensor nodes, a frequency modulation receiver and a host on the Internet. A universal gateway node is structured by software wireless technology and comprises front-end hardware equipment and a rear-end software module, wherein the rear-end software module runs on a universal computer; and the front-end hardware equipment and the rear-end software module are connected through a wire. The universal gateway node can communicate with any experimental equipment and also can realize conversion of various heterogeneous network protocols. The invention designs a heterogeneous network experimental device embodiment and also designs a data transmission experimental embodiment on the basis of the heterogeneous network experimental device embodiment. Compared with the traditional device, the software wireless technology-based heterogeneous network experimental device has rich content of courses and an open experiment environment and it is convenient for students to study and research various heterogeneous networks and more heterogeneous networks.

The invention discloses a method and a device for updating a frequency modulation broadcast channel list. The method comprises the following steps of: acquiring radio station information of a current channel list; if a radio station of which the signal intensity is less than a preset signal intensity threshold value exists in the current channel list, starting a channel list updating function; positioning regional mark information of a position where a mobile phone is located; quickly acquiring the radio station information of the position where the mobile phone is located; and extracting the radio station of which the signal intensity is greater than or equal to the signal intensity threshold value to update the current channel list. According to the method, when listening to a radio, a user can quickly find out a specified channel to listen to a radio station program without updating the channel list every time when the radio is turned on, so that the electric energy consumption is reduced to a certain extent, and the user experience effect is improved.

A processing front-end for FM radio signals includes a receiver, a filter, and a mixer. The receiver obtains an FM radio signal including data content centered at a data frequency and programming content. The filter is coupled to the receiver and removes the programming content from the FM radio signal. The mixer accepts the filtered FM radio signal and shifts the center frequency of the data content to a lower frequency than the first frequency. The lower frequency is selected according to a sampling rate available in an analog-to-digital converter present in a subsequent processing stage, typically a low cost digital signal processor.

There is provided a combined TV and FM radio receiver for selectively receiving TV and FM radio signals via a single tuner using a digital intermediate frequency (IF) stage. The receiver includes a tuner that selects TV band or FM radio band signals and converts the selected signals into IF signals or primary sound IF signals; an IF processor that generates local oscillating signals depending on whether a current mode is a TV mode or an FM radio mode, and converts the IF signals and / or primary sound IF signals, into baseband signals and secondary sound IF signals, respectively; a video demodulator that extracts video signals; an audio demodulator that extracts TV audio signals and FM radio signals according to TV sound or FM radio mode data; and a controller that controls the tuner, and the IF processor, and applies the TV sound or FM radio mode data to the audio demodulator.

The invention relates to a navigation method, terminal, information processing center and navigation receiver based on frequency modulation data broadcast. The method includes: receiving and demodulating received to-be-identified information; obtaining real satellite ephemeris and / or cheating interference source information according to the to-be-identified information; sending the real satellite ephemeris and / or the cheating interference source information to an anti-cheating information processing center by employing data frequency modulation broadcast signals. The real satellite ephemeris and the cheating interference source information are sent by employing the mode of the data frequency modulation signals, the advantage of low cost can be maintained based on the wide service coverage, the reliability of the navigation system is improved, the sending process of navigation information does not need a mobile communication network, and a lot of network connection resources are saved; besides, the frequency modulation data broadcast is employed as the distribution means so that the data propagation speed is fast, and the timeliness of information transmission is guaranteed.

A mobile phone with FM antenna includes a mobile phone body, an FM antenna, an FM microchip and a phone case. The FM antenna is fixed to an outer side of the mobile phone body. One end of the FM antenna has a feed point, and the other end of the FM antenna is an opening end. The FM antenna resonates at FM radio frequencies so as to receive FM radio signals. The FM microchip is disposed on the mobile phone body and coupled with the feed point of the FM antenna for processing the FM radio signals. The phone case encloses the mobile phone body, the FM antenna and the FM microchip. Thus the FM antenna is embedded in the mobile phone to enable the mobile phone to receive FM radio without extra external earphones.

PCT No. PCT / JP96 / 03681 Sec. 371 Date Aug. 14, 1997 Sec. 102(e) Date Aug. 14, 1997 PCT Filed Dec. 18, 1996 PCT Pub. No. WO97 / 23998 PCT Pub. Date Jul. 3, 1997An FM radio receiver receives and displays program data which is affixed with a return destination box number and return form type data and has been transmitted from an FM broadcasting station 1 in the multiplexed form on FM broadcast radio waves. In responding to a displayed program through the FM radio receiver, first, the FM radio receiver 2 reads a return form corresponding to the return form type data from a ROM card 24 and displays the form. A user inputs return message data according to the displayed return form. FM radio receiver 2 transmits the return destination box number data in addition to the return message data to a service center 5. The service center 5 stores the received return message data in a box corresponding to the return destination box number data affixed to the received return message data. The return message data is edited and collected box by box. The edited and / or collected results are sent to the FM broadcasting station 1 as needed.

The invention discloses a frequency modulation broadcast outer radiation source radar object detection method based on waveform cognition. The method comprises steps of first recovering direct wave signals of different broadcasting stations in a reference channel; performing radiation source waveform cognition processing in the reference channel and selecting a radiation source; using a self-adaption compensation method to suppress the direct wave and the multipath clutter for signals received by a receiving array in a monitoring channel; and performing distance Doppler cross correlation calculation on compensation residual signals and direct wave signals of the selected radiation source in the reference channel, to achieve screening of the frequency modulation broadcast signal for objectdetection. Therefore, the technical problem that the bandwidth of the partial frequency modulation broadcast signal is not suitable for the object detection.

The invention discloses a frequency modulation (FM) broadcasting signal receiving and monitoring system. The FM broadcasting signal receiving and monitoring system comprises a plurality of FM receiving and monitoring receivers and a monitoring terminal, wherein the FM receiving and monitoring receivers are mounted at a plurality of check stations in an effective range covered by FM signals transmitted by an FM transmitter, and the monitoring terminal consists of a computer; the FM receiving and monitoring receivers and the FM transmitter respectively access to a mobile communication network; the mobile communication network and a system server respectively access to the Internet; data sent by the FM receiving and monitoring receivers is transmitted to the system server; and the monitoring terminal monitors information acquired by the FM receiving and monitoring receivers or carries out setting and adjustment on parameters of the FM receiving and monitoring receivers in a manner that the monitoring terminal accesses to the system server through the Internet. Thus, data such as locations, working conditions and the like of the FM receiving and monitoring receivers arranged at various places are all displayed on a satellite map on a screen of the monitoring terminal computer, the working conditions of all the stations in an FM coverage network are comprehensively and visually reflected, and finally, the aim of off-site, remote, cross-regional and real-time monitoring is achieved.

The invention provides an earphone supporting a FM function. The earphone comprises a decoding control unit, a sound production unit, a connection unit and a FM demodulation chip. The decoding control unit is connected to the connection unit and the FM demodulation chip respectively. The connection unit is used for establishing connection with intelligent equipment through a wireless connection mode or a wired connection mode. The decoding control unit comprises a controller and is used for parsing a radio control instruction which is output by the intelligent equipment and is received through the connection unit, converting into a FM control instruction and sending to the FM demodulation chip. The FM demodulation chip is used for receiving a FM broadcasting signal according to the FM control instruction and outputting a FM audio signal generated by demodulating the FM broadcasting signal to the decoding control unit. The decoding control unit also comprises a decoder and is used for processing the FM audio signal and then outputting to the sound production unit so as to carry out sound production. By using the earphone, a problem that a user needs to increase data flow cost when hearing FM broadcasting can be solved.

The invention provides a broadband broadcasting transmission method and system. A software defined radio (SDR) technology is utilized, a structure of a transmitter is largely simplified, complex multi-frequency modulation is implemented in an SDR manner, only one transmitter (for reducing device performance requirements, two or four transmitters can also be utilized) is needed to complete the whole coverage of FM broadcasting with the 20 Mhz bandwidth, and any one normally operating radio can receive signals transmitted by the transmitter without tuning as long as the radio is turned on. Furthermore, the device costs and the maintenance costs are low, the broadband broadcasting transmission method and system can be widely applied to information transmission of an electromagnetic shielding space, and have promotion and application values on the aspects of disaster prevention and reduction. The same method can also be applied to AM broadcasting, even digital broadcasting.

The invention discloses a system, a method and a base station for integrating mobile communication and FM broadcast function, the core ideas are as follows: in the base station, each base transceiver station is allocated with a satellite synchronous time service unit, a synchronous exciter and a frequency modulation transmitter correspondingly and respectively; then the satellite synchronous time service units acquire GPS time scale signaling information and send to operation maintenance units of the frequency modulation transmitters and the base transceiver stations; the operation maintenance units calculate pulses per second of GPS and send to the synchronous exciters which lock the carrier frequency of the frequency modulation transmitters; the frequency modulation transmitters receive frequency modulation signals, extract GPS time scale signaling information and compares the GPS time scale signaling information with the GPS time scale signaling information from the satellite synchronous time service units, thus obtaining link time-delay, and therefore, the frequency modulation signals are broadcast after compensation. By adopting the system, the method and the base station, synchronous covering of communication signals and FM broadcast signals is realized, thus avoiding repeated construction of basic facilities, such as iron towel rooms and the like and reducing the cost.

The invention provides a method for achieving the time service through FM (frequency modulation) broadcast, and the method comprises the steps: inserting standard time information into an FM broadcast signal in an SCA channel of the FM broadcast through employing the pseudo-random code spread spectrum modulation technology, and carrying out the broadcasting; enabling a receiving end to receive the FM broadcast signal, demodulating the moment information and time information from the FM broadcast signal, and achieving the high-precision time service. According to the invention, through the coding of the time information and the spread spectrum gain of a PN code, the method is provided under the condition that the normal operation of a conventional FM broadcast is not affected. The time precision corresponding to the bandwidth of 5KHz is 0.2 millisecond, and the precision of time service is at the level of sub-millisecond after the impact from a transmission distance is removed.