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95 results about "Broadcast band" patented technology

A broadcast band is a segment of the radio spectrum used for broadcasting.

Underground positioning and safety monitoring system on basis of communication network

The invention provides an underground positioning and safety monitoring system on the basis of a communication network, which comprises a ground control center, a plurality of personnel positioning terminals, a plurality of short message positioning terminals, a plurality of voice communication positioning terminals, a plurality of wireless positioning base stations and a base station gateway. The personnel positioning terminals carry out timing on broadcast signals by broadcast bands; the base station gateway or the wireless base stations receive the broadcast signals, acquire contents and the signal strengths of the broadcast signals, encapsulate information according to a protocol, transmit the information to the ground control center by the network for positioning processing, and acquire corresponding position information; meanwhile, a mobile node adopts a timing POLL mechanism to receive a downlink command of a data center so as to realize bidirectional data transmission, and a network base station controls illumination equipment to realize energy-saving production according to existence or non-existence of the mobile node in a current region. The underground positioning and safety monitoring system has the characteristics of high reliability, simplicity in construction and accuracy in position.
Owner:中滦科技股份有限公司

Method and system for receiving digital broadcasting signals in frequency modulation (FM) broadcast bands

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.
Owner:SHENZHEN SIKAIWEI ELECTRONICS CO LTD

Composite modulation system compatible with medium-wave analogue amplitude modulation (AM) broadcast

The invention discloses a composite modulation system compatible with medium-wave analogue amplitude modulation (AM) broadcast. According to the system, a low-sideband m-ary position phase keying (MPPSK) signal with modulated high-speed data is adopted to replace a sinusoidal carrier; carrier-retained double sideband amplitude modulation is performed with an analogue audio signal; after a receiver performs up-conversion and impacting filter on the received composite modulation signal and extracts a coherent carrier to multiply, an analogue audio signal is separated by using spectral distribution difference, and MPPSK modulated data is demodulated by using correlation matching. According to the system, the frequency resource and the 9 kHz bandwidth division of the conventional medium-wave amplitude modulation broadcast band, the infrastructures of an amplitude modulation broadcast transmitter, the broadcast system of DSB-AM (Double Sideband Amplitude Modulation) transmission and a mature product of a medium-wave amplitude modulation radio are directly used to realize that the original analogue sound signal and a new digital code stream are really broadcast at the same bandwidth on the same channel at the same time, so that the spectrum utilization efficiency and the energy utilization rate of the digital AM broadcast system are greatly improved.
Owner:苏州东奇信息科技股份有限公司

Separation method and receiving device of digital broadcasting analog-to-digital (A/D) signal at frequency modulation (FM) broadcast band

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.
Owner:SHENZHEN SIKAIWEI ELECTRONICS CO LTD
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