Typical measurement setup for SECO ultrasonic transducers

Test circuit

To measure our ultrasonic transducers, we use a proven test circuit internally at SECO. This forms the basis for the technical data in our product data sheets. This circuit can be reproduced for the initial commissioning of our products. Of course, our ultrasonic transducers can also be operated with a wide variety of customer-specific test circuits.

Contact our ultrasound experts for tips and tricks! We look forward to hearing from you.

Test setup & test circuit

Pulse-echo operation

We determine the electro-acoustic parameters of our data sheets using our tried-and-tested SECO test circuit. This measures the transducer in pulse-echo mode against a reflector. This results in the technical data and electroacoustic properties that you can read about for each of our transducers in the respective data sheet.

For further information on the test circuit, the initial commissioning of your transducer or necessary customer-specific adaptations, please contact us. We look forward to hearing from you!

Kunden verwenden den Impuls-Echo-Betrieb typischerweise für Messaufgaben der Anwesenheitskontrolle, Abstandsmessung oder Füllstandsmessung. Den alternativ möglichen Sender-Empfänger-Betrieb finden Sie hier.

Electronic accessories for our SECO test circuit

Electronic control unit/ DAC

  • Excitation of the ultrasonic transducer
  • Generation of pulse and sine burst signal
  • Frequency control

Antiparallel diodes

  • e.g. BAV20
  • Smoothing the signal
  • Protection of electronic components against voltage peaks

Reflector at a defined distance

  • Only in pulse-echo mode
  • Min. 100×100 mm, flat surface
  • Longitudinal axis perpendicular to the transducer

Amplifier

  • If ADC has no amplifier unit
  • Especially with high-frequency transducers
  • Increase signal-to-noise ratio
  • Bandpass for suppressing high frequencies

Oscilloscope / ADC

  • Evaluation of the received signal
  • Signal visualization with regard to signal shape
  • Amplitude and frequency in real time, frequency analysis

BNC connection cable

  • Better signal quality, connection stability
  • Maximum freedom from interference
  • Minimized signal distortion, especially at high frequencies

Transducer-specific settings of the test circuit

We basically differentiate between three transducer types, which we have optimized in terms of their electro-acoustic functionality and structure to suit their different strengths. The specific settings of the test circuit for each transducer type can be found in the following tables.

Product group SC007 SC010 SC021 SC029 SC031 SC042 SC049 SC508 SC517 SC520 SC524
Excitation voltage at the transducer [Vpp] 10 10 10 10 10 10 10 10 10 10 10
Type of excitation Sine Sine Sine Sine Sine Sine Sine Sine Sine Sine Sine
Burst cycles 40 40 12 12 12 12 12 40 12 12 12
Distance transducer-reflector [mm] 460 288 100 60 60 60 60 432 100 100 100
Data sheet DB007 DB010 DB021 DB029 DB031 DB042 DB049 DB508 DB517 DB520 DB524

Size of the reflector at least 100 x 100 mm, longitudinal axis of the transducer perpendicular to the reflector

Elektroakustische Parameter der Wandler

Gemessen mit unserer SECO-spezifischen Prüfschaltung ergeben sich für unsere Ultraschallwandler folgende elektroakustischen Parameter:

Product group SC007 SC010 SC021 SC029 SC031 SC042 SC049 SC508 SC517 SC520 SC524
Echo voltage (unamplified) [mVpp] > 5 > 4 > 10 > 3,3 > 8,2 > 6,4 > 0,6 > 6 > 12 > 11,2 > 10
typ. Echo voltage (unamplified) [mVpp] 6…11 5…11 ~ 13 ~ 4,5 ~ 11 ~ 8,5 ~ 0,8 7…12 ~ 16 ~ 15 ~ 13
Decay voltage [mVpp] 10 10 10 10 10 10 10 10 10 10 10
Decay time @ decay voltage [µs] < 1500 < 1000 < 350 < 150 < 175 < 140 < 80 < 1600 < 330 < 290 < 270
Data sheet DB007 DB010 DB021 DB029 DB031 DB042 DB049 DB508 DB517 DB520 DB524

Boundary conditions for measuring the electroacoustic parameters:

Electronic settings

Excitation type, burst cycles, spacing see “Transducer-specific settings of the test circuit” [insert anchor link]

Ambient conditions

Size of the reflector at least 100 x 100 mm, longitudinal axis of the transducer perpendicular to the reflector

Reflector

Measurement in medium air at room temperature and relative humidity < 25 %

Do you have any questions or need further tips & tricks?

Customer proximity and an intensive exchange of ideas are our top priority. We would be happy to discuss further details about our ultrasonic transducers with you or advise you on initial commissioning.

We look forward to your inquiry.

eugen.gergert@seco-sensor.de +49 (0)9561 869-147
Your contact Managing Director Eugen Gergert from SECO Sensor

Eugen Gergert

Managing Director

Schematic signal curve

Typical echo signal of an ultrasonic transducer after sinusoidal excitation:

Details on signal progression:

  • UA = Decay voltage
  • UE = echo voltage
  • bc = number of burst cycles
  • rc = number of echo decay cycles (UE to 1/2 UE)

Typical directional characteristic

Directional behavior and beam width of our three transducer types

Focused transducer

Focused transducers are characterized (according to their name) by a very narrow sound beam and a small beam width.

Typical values here are approx. 7…11° (@ -3dB). Comparatively long ranges are possible with them, which is why they are used in distance measurement and level measurement, among other things.

Multi-use transducer

In contrast, our multi-use transducer have a particularly wide sound beam and large beam widths of typically approx. 12…20° (@ -3dB).

A wide sound beam enables accurate measurements even at very high flow velocities or strong drifts in the wind measurement.

Pulsed transducer

The beam width of our pulsed transducers depends on the frequency due to the broadband characteristics of this transducer.

The directional diagram therefore shows two other frequencies below and above the typical 200 kHz operating frequency.

Alternative operating mode: Transmitter-receiver mode

Customers typically use our ultrasonic transducers in transmitter/receiver mode for measurement tasks such as flow measurement, double sheet control, web edge control, label detection and presence detection. The ultrasonic signal travels between two transducers (transmitter and receiver) and is then evaluated. The travel distance is therefore only half as long as in pulse-echo mode, in which a single transducer emits sound against a reflector.

Background information on the test circuit

Ultrasonic transducers generate and receive sound waves in the ultrasonic range. Their functionality and performance are tested using a test circuit. This comprises several key components. First, a function generator or high voltage generator is used to generate an electrical signal that drives the ultrasonic transducer. This signal is then passed through a power amplifier to ensure it is strong enough to activate the transducer.

The transducer itself converts the electrical signal into mechanical vibrations that are emitted as ultrasonic waves. These waves can then be detected by a receiver, often a second transducer. The receiver converts the ultrasonic waves back into an electrical signal.

This signal is then amplified by a preamplifier and sent to an oscilloscope or spectrum analyzer. With these instruments, the user can analyze the frequency, amplitude and shape of the received signal. By comparing the output and input signals, the performance and accuracy of the ultrasonic transducer can be evaluated. These test circuits are essential to ensure that ultrasonic transducers work accurately and reliably in medical, industrial and scientific applications.

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Head office

SECO Sensor Consult GmbH
Am Bleichanger 1
96450 Coburg

Phone: +49 (0)9561 869141
Fax: +49 (0)9561 869149
info@seco-sensor.de

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