The Key Techniques Of Receiver For The FM Radio Time Service

With the development of society and science and technology,people on the application of timing technology and timing accuracy of the more stringent requirements.Currently the most widely used is the use of satellite systems to provide timekeeping services.However,although the satellite timing can provide a higher timing accuracy,but the satellite signal is very susceptible to environmental factors,in many cases difficult to display.In the building-intensive urban environment,the satellite timing effect is not good.Taking into account the wide range of FM radio users in China,the terminal equipment is simple and inexpensive,the technology is mature and so on,the use of existing FM radio system to achieve timing services is also a promising new method of timing.And our FM radio spectrum resources are very limited,the radio channel spacing between the 200 kHz,the rational use of these spectrum resources,the expansion of the FM sub-channel can effectively improve the spectrum of resource utilization and for our lives to create a lot of convenience.FM radio timing because of the use of off-the-shelf FM radio system,and FM frequency band will not interfere with FM radio,is a cost-effective timing method.Therefore,the paper proposes to use the idle sub-channel SCA in the FM broadcasting system to carry out the timing service and design the corresponding time-receiving receiver.The paper first introduces the system of several different FM broadcast signals,and finally establishes the SCA subchannel to develop the FM broadcasting service,and tells the basic principle of FM signal timing.The BPSK + FM secondary modulation mechanism is determined at the transmitter.According to the characteristic of the transmitter and the characteristics of the spread spectrum technology,the specific receiving scheme is designed and the key technical problems to be solved are analyzed.Through the design of band-pass filter and matched filter,including parameter design,simulation verification and FPGA-based circuit implementation,it focuses on solving the key technical difficulties of signal acquisition.Finally,the FM radio receiver is implemented with the mixed architecture of FPGA + DSP,and the various modules of the receiver are designed in detail.The design of baseband signal processing module is the focus of this paper.The design adopts high-performance,high-speed FPGA and DSP chip to realize the processing and demodulation of baseband signal.And each part of the processing process to do a detailed account.The experimental results show that the FM-SCA-based timing receiver can basically complete the reception and calculation of the FM broadcast timing signal,and verify that theprogram is based on the FM-SCA timing receiver.feasibility.And the output of the receiver1 pps points and rubidium atomic clock 1PPS output and GNSS receiver 1PPS output comparison,the results are considerable,to achieve a certain accuracy of the timing service.At the same time,the paper discusses some problems in the subject and puts forward the improvement direction.