Emergency announcement call system based on FM/Chirp modulation
A communication and modulator technology, applied in the field of emergency communication system, can solve the problem that it is difficult to meet the number requirements of communication frequency sweeping rules, and achieve high emergency application value and good application effect
Inactive Publication Date: 2015-04-22
周运伟
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Problems solved by technology
Limited by the physical structure of the Surface Acoustic Wave (SAW) device used for Chirp pulse carrier generation and demodulation, traditional Chirp modulation is difficult to meet the quantity requirements for frequency sweep in communication
Method used
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[0016] This embodiment is used to illustrate the parameter selection and application fields of the emergency communication system based on FM / Chirp modulation provided by the present invention. figure 1 For the system structure shown, see the relevant description in the previous part for its working process, which will not be repeated here. A typical working parameter design of the emergency communication system is as follows: The baseband signal to be modulated is an analog voice with a frequency range of 300-3KHz, and the specific modulation method for FM modulation of the Chirp pulse carrier in the FM / Chirp modulator (11) is Analog linear FM (16F3), the sweep period of the Chirp pulse carrier used in the FM / Chirp modulator (11) is 80 microseconds (corresponding to the sweep rate of 12.5K cycles / second), narrowband FM receiving terminal (151- 15N) Using 25KHz receiving carrier channel bandwidth and frequency demodulation according to analog linear FM (16F3) mode, FM / Chirp modu...
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The invention relates to an emergency announcement call system based on FM / Chirp modulation and belongs to the emergency communication field. The emergency announcement call system is formed by a FM / Chirp modulator, a power amplifier, a transmitting antenna, narrowband FM receiving terminals and channels which connect the transmitting antenna with the each narrowband FM receiving terminal. A baseband signal to be modulated is input to the FM / Chirp modulator so as to carry out carrier wave modulation. Power amplification is performed on an obtained FM / Chirp modulated carrier wave by the power amplifier, and then the modulated carrier wave is emitted through the transmitting antenna, passes through channel transmission and is taken as an input signal of the corresponding narrowband FM receiving terminals. The narrowband FM receiving terminals demodulate and recover a reduction sample of the baseband signal to be modulated from the received FM / Chirp modulated carrier wave. By using the emergency announcement call system provided in the invention, announcement call covering to a plurality of narrowband carrier wave channels can be realized only through transmitting one FM / Chirp modulated carrier wave. Current narrowband FM receiving equipment can be still used and a working mode does not need to be converted. It is convenient to use a resonance power amplifier to realize large power transmission and long distance covering.
Description
Technical field [0001] The invention relates to an emergency communication system based on FM / Chirp modulation, which belongs to the field of emergency communication. Background technique [0002] There are three main types of dedicated mobile communication systems: single-frequency conventional, dual-frequency conventional, and trunking. They mainly work in group calling and mainly transmit voice or data for dispatching and commanding. In the single-frequency conventional and dual-frequency conventional systems, the terminals of the same talk group wait on the same frequency carrier channel; in the trunking system, each terminal in the same talk group waits on the control channel of the base station to which it is connected. Under normal circumstances, different talk groups are waiting on different frequency carrier channels, and each talk group does not need or allow intercommunication. However, during emergency incident handling, due to the need for coordinated dispatch and c...
Claims
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IPC IPC(8): H04L27/12H04L27/14
Inventor 周运伟
Owner 周运伟