Push-pull oscillating circuit of transponder
Technical field
The utility model relates to the responser in the railway communication system, is the push-pull oscillator circuit that can produce fsk signal in this responser specifically.
Background technology
Responser is an equipment in the railway communication system, and it comprises transmit receive antenna 1, push-pull oscillator circuit 2, and clock generation circuit 3, message read circuit 4 (referring to Fig. 1).In the transmittance process of responser message information, need modulate information transmitted, to ensure data message reliability in transmittance process.The modulation system of having stipulated information transmission between transponder device and the mobile unit in European responser standard is the FSK modulation.
Summary of the invention
For realizing the FSK modulation of responser information, the purpose of this utility model is to provide a kind of push-pull oscillating circuit of transponder that can produce fsk signal.
The purpose of this utility model is achieved in that it has push-pull oscillator circuit, it is characterized in that: the resonant capacitance in push-pull oscillator circuit is replaced by capacitance network, said capacitance network is that four capacitor C 0-C3, two electronic switchs and the earth point D between these two electronic switchs constitute, four capacitor C 0-C3 are connected into enclosed shape successively mutually, the two ends of one of them capacitor C 0 are mouth, respectively connect an electronic switch with two ends of mouth symmetry, these two electronic switch parallel connections.
The D point is as the zero point of radio frequency AC signal, and it can be received on the power supply, also can receive on the ground.When electronic switch was opened, the electric capacity of capacitance network was C=1/ (1/C1+1/C2+1/C3)+C0; When electronic switch closed, the electric capacity of capacitance network was C=1/ (1/C1+1/C3)+C0.The unlatching of electronic switch and close and, having changed capacitance network is the capacity of resonant capacitance, thereby has reached the purpose of push-pull oscillator circuit frequency conversion, promptly produces fsk signal.The two scale notation message control that the break-make of electronic switch is subjected to reading from ROM, if read as 1, switch disconnects, if be zero, switch closure perhaps adopts opposite logic level control electronic switch.
The utility model compared with prior art, it has utilized capacitance network to realize frequency conversion purpose, good reliability dexterously on push-pull oscillator circuit.
Description of drawings
Further specify the utility model below in conjunction with accompanying drawing.
Fig. 1 is the formation block diagram of responser.
Fig. 2 is the push-pull oscillating circuit of transponder schematic diagram.
Fig. 3 is the capacitance network schematic circuit diagram.
The specific embodiment
Referring to Fig. 2, by two bipolar transistors or two field effect transister T1 and T2, resonant capacitance C and two coupling capacitance C5, C6, the vibration that produces constant frequency in the mode of recommending.The utility model replaces to capacitance network shown in Figure 3 with resonant capacitance C, capacitance network is that four capacitor C 0-C3, two radio frequency electric K switch and this earth point D between two electronic switchs that are made up of field effect transister constitute, four capacitor C 0-C3 are connected into the sealing rectangle successively mutually, the two ends of capacitor C 0 are output terminals A and B, with two ends of output terminals A and B symmetry be that two ends of C3 respectively meet an electronic switch K, these two electronic switch parallel connections.
The D point is as the zero point of radio frequency AC signal, and it can be received on the power supply, also can receive on the ground.When electronic switch was opened, the electric capacity of capacitance network was C=1/ (1/C1+1/C2+1/C3)+C0; When electronic switch closed, the electric capacity of capacitance network was C=1/ (1/C1+1/C3)+C0.The unlatching of electronic switch and close and, having changed capacitance network is the capacity of resonant capacitance, thereby has reached the purpose of push-pull oscillator circuit frequency conversion, promptly produces fsk signal.Referring to Fig. 1, the FSK radiofrequency signal of generation radiate by antenna 1, and the vehicle-mounted BTM receiver that this fsk signal will be skimmed over this responser receives.The fsk signal that push-pull oscillator circuit produces is sent to again in the clock generation circuit 3, in order to produce the clock that promotes the work of responser sequential logical circuit.ROM reads circuit and produces the sequential of reading ROM, and the message data that is stored among the ROM is read out, and delivers to then in the oscillating circuit 2 as fsk modulated signal.The two scale notation message control that the break-make of electronic switch is subjected to reading from ROM, if read as 1, switch disconnects, if be zero, switch closure perhaps adopts opposite logic level control electronic switch.