Sonar Ranging Module The SRM400 is a sonar ranging module utilizing our new developed Sonar Ranging IC, PW-0268, which can work with all our PT or EP type transducers. SRM400 provides as a shortcut to develop car reversing systems or some other distance measurement systems for design engineers who are not very familiar with analog circuit and/or the operation of ultrasonic transducers. By using this module engineers can focus firstly on the other fields of digital circuit and software designs as well as some other mechanical issues. After first stage then you can either design your own analog circuit based on the module construction or consult with factory for making your own module for your special needs. Features: z z z z z z z z Operating Voltage: 6 – 10Vdc single source Operating Frequency: broadband output ranging up to 250KHz Built-in variable RC oscillator matching transducers with different frequencies High Gain Amplifier: varies with time over 32 steps Integrated Band Pass Filter: reduces external component count, Bi-direction I/O Pin: simplifies the control function for transmitting a pulse and receiving an echo An adjustable System Clock: enables the control of, the number of pulses transmitted, the slope of the variable gain amplifier, and the pulse repetition rate Board size: 27.9 * 18 mm (L*W) SRM400 Specification: Operation voltage Operation current Oscillation frequency Amplifier gain Pre-Amplifier 2nd Stage Amplifier Time controlled 32 steps main amplifier Bandpass filter DC6 - 10V <20 mA ＠DC10V Variable RC oscillator 14 dB 30 dB 35 dB max. Fc: 38 KHz Bandwidth: 20KHz Insertion loss: 1 dB 130Vpp; pulse width 0.5ms Driving voltage (no load) Bi-directional I/O Input signal Open collector pull low Output 0..05*Vcc to 0.9*Vcc digital echo signals Measuring distance 25 – 150 cm SRM400 includes: 1. Module board 2. 400EP14D enclosed type transducer of asymmetrical beam patterns, see detail specification of 400EP14D. 3. Detail electrical schematic S. Square Enterprise Company Limited Pro-Wave Electronics Corporation P.O. Box 1-70 Chung Ho, Taiwan, ROC; E-mail: [email protected]; Tel: 886-2-22465101(5 lines), 22459774; Fax: 886-2-22465105 http://www.s2.com.tw ; http://www.prowave.com.tw Sonar Ranging Module SRM400 Electronic Circuit Diagram Vref Vcc BAV99 Vref Vcc Vreg Test "C" 3 100 2200p 1 220u 1K User Side 47K 100u Vcc 100u 22p 3 2 1 3 2 1 3 2 1 4 IFT 3.3K 1.5K 100u 400EP14D Vref 511 Vcc 20K 2 BSS123 Ultrasonic Transducer 660KHZ 20 19 17 18 16 14 15 13 12 11 Test "B" 6.8K PW0268 MMBT3904 10K 1 2 3 5 6 2200p 2.7K Echo High Level Pulse 7 8 9 10n 33K 680p 680p BAV99 13K Test "A" Test "E" 10 4.7K 10n Test "F" MCU 4 4.7K Test "D" 470p Vref Vref Vref Signals at different test points: works with transducer model 400EP18A against a hard target of size of 20cmL*20cmW*1cmT at distance of 50cm “B” Point: Tone bursts Signal “A” Point: Control Pulse (from MCU) H: 0.5ms/div V: 5V/div “C” Point: Transducer loading H: 0.5ms/div V: 50V/div “E” Point: Main 32 Steps TCG Amplifier H: 0.5ms/div V: 1V/div Refer to PW-0268 Sonar Ranging IC for detail information. H: 0.5ms/div V: 5V/div “D” Point: 1st Pre-Amplifier H: 0.5ms/div V: 20mV/div “F” Point: Digital Echo signal Output H: 0.5ms/div V: 5V/div