Development of ultrasonic acoustic ranging transducer

 An acoustic ranging sensor is developed to measure the separation distance between rocket stages. The structure is a radioactive source and exploration.The distance measuring transducers are mounted face-to-face on two-stage rockets, and the number of particles detected during the separation process is converted into a DC voltage .which sent to a telemetry system or magnetic recorder to measure the instantaneous separation distance. When the separation speed does not exceed 25 m/s and the measure separation distance is in the range of 0 to 2 meters, the accuracy can reach 10%; if it exceeds this range, the measurement accuracy of 100KHz ultrasonic distance sensor will deteriorate.It is the ground experiments and environmental simulation tests.The instrument consists of a radioactive source, a receiver, and an inverter. In order to adapt to the shock and vibration environment, all electronic circuits are potted with silicone rubber. The radioactive source has an intensity of 10 millilitres. The gold-silicon barrier-type semiconductor ultrasonic distance measuring transducerhas a sensitive area diameter of 20 mm, and the silicon material is used for the resistivity of about 100 to 200 ohms. The reverse current is less than 0 when a bias of 10 volts is applied at room temperature.

  When high accuracy distance sensor is assembled, an aluminum foil with a thickness of 2 mg/cm2 was used to cover the surface to shield the space from solar radiation. The collimation device limits the maximum acceptance angle to sense amplifiers by using field effect transistors . The preamplifier is in the form of a "four-transistor feedback network",it is featuring low input and output impedance, fast rise time and good temperature stability. 

The pulse amplitude discriminator adopts the high-speed voltage comparator. Waterproof ultrasonic distance sensor has the characteristics of small size, power consumption,

high sensitivity and fast response. When the voltage of the inverting input is 3 mV lower than the reference voltage of the inverting , there is a high level (about 32 volts) output;if the voltage 

at "2" is higher than "3" There is a low (about 0 volt) output when the reference voltage is applied. The instrument takes a value of 45 millivolts.The output pulse of ultrasonic range sensor rises and falls less than 20 nanoseconds.The pulse shape uses a high-speed dual NAND

 gate integrated circuit T 21 A` to form an integral type monostable circuit.the rate converter 

uses a triode ratio. It is table circuit, time constant RIC.

The relationship between output DC voltage input count rate N is experimentally determined to match the design specifications.In order to compress a DC voltage plant with several orders of magnitude of variation, a logarithmic amplifier is used to apply a silicon transistor as a feedback element to obtain the logarithmic conversion characteristic to counteract the effect of the temperature-dependent transistor reverse current, plus an offset. Current and offset voltages of ultrasonic distance measurement sensor are zeroed to extend the linear range of the low level. The experimentally had the conversion characteristicswhich are consistent with the design 

and the output voltage at temperature room.