VHF Frequency-hopping Radio Receiver Front-end Research And Implementation

The application of radio communication technology is more universal as the rapid development of the microelectronic technology,digital signal processing technology and wireless communication technology,and it's impact on people's daily life is also growing.Today's electromagnetic environment has become more and more complex,the interference between the communications equipment is more serious,but the limited scope of the available radio spectrum,frequency bands become increasingly apparent contradictions in the crowded,which requires the receiver must have a more superior performance to meet the complex and the harsh environment,and to meet the good communication requirements.VHF frequency-hopping radio receiver as an important military communication carrier,the environment which they used is more complex,more serious interference problems are faced.It need to improve the receiver's signal detection capabilities,and to enable the receiver have the abilities of higher applicability,stronger anti-jamming capability,larger dynamic range,smaller volume,lower power and less cost,and so on.Due to the excellent secrecy,anti-jamming and multi-site communications ability,Frequency-Hopping Spread Spectrum(FHSS)technology is more widely used in military and civilian domain.Frequency-Hopping radio with great value in research and development,has become the focus of the military communications.The topic from a new generation of VHF frequency-hopping radio project for which the receiver RF front-end development.The receiver front-end ensures that receiver to achieve high selectivity,large dynamic range,strong anti-interference,and excellent adaptability,using a superheterodyne structure with twice conversions,using a NC capacitor array approach designed for frequency-hopping pre-filter,for full-band filter,and the front-end circuits designed for a superposed structure to reduce the volume;In IF amplification unit using two pairs of cell junction transistor amplifier circuit with integrated circuit SA615,variable gain amplifier AD603 and automatic gain control circuit to achieve the gain,and the quartz crystal filter to ensure the frequency selective.There are some innovations in the design of frequency-hopping preselector,IF AGC,high selectivity and large dynamic range of receiver and small-sized structure,also in the circuitry realization.The paper begins with the introduction of the principle of frequency-hopping communication technologies,and describes the characteristics of frequency-hopping communication systems;Followed by a comparative analysis of the structure of receiver,and then put forward the design proposal of the work,the key parameters and technical difficulties.Subsequently,analysis key parameters of the receiver,author presents the design proposal to achieve the targets and proof.Then elaborate the specific circuit of the subject,implementation of each functional unit,including the high-frequency amplification unit and the IF amplification unit,namely,through their design to achieve large dynamic range and high selectivity.Finally,the circuit is debugged,and the ultimate system test results are given.At the same time,author does some analyzing and presents the practical solutions for the problems in debug.