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Power Emitted by SRF04 ultrasonic ranger — Parallax Forums

Power Emitted by SRF04 ultrasonic ranger

AungAung Posts: 3
edited 2005-09-26 14:26 in Learn with BlocklyProp
Hello everyone,

I am now starting to work with SRF04 ultrasonic ranger on· activity tracking system. I checked in its datasheet but I could not find the power emitted by this small ultrasound ranger.

I would like to what is the power emitted by this sensor( in terms of mW) if u've·already known·or how to measure the output power? And also do you have any idea how to measure poower emitted by this kind of sensor that are operating at 40 kHz?

Thanks you so much.

Regards,
Aung
·

Comments

  • Bruce BatesBruce Bates Posts: 3,045
    edited 2005-09-24 07:42
    Aung -

    Since sound is measured in terms of pressure, I presume the output power would be measured in db (decibels). Watts are wholly a mechanical and electical energy measurement (746 W = 1 HP, W = V x A). I can only guess you'd need a decibel meter suitable for ultrasonic frequencies to measure it.

    What is the point in knowing this parameter, just curious?

    Regards,

    Bruce Bates
  • Jon WilliamsJon Williams Posts: 6,491
    edited 2005-09-24 14:43
    The SRF-04 is manufactured by Devantech in the UK. You might want to check with them on this measurement as this may be something that they've calculated or tested. I'm with Bruce, and not sure how valuable this bit of information would be for application giving the range and other data are well known.

    Devantech web site: http://www.robotelectronics.com/

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    Jon Williams
    Applications Engineer, Parallax
  • AungAung Posts: 3
    edited 2005-09-26 00:35
    Hello,

    Thanks for all of your replies. I need to know exactly how much power emitted because I need to deploy these sensors in hospital room to monitor the activities of the patient in my project. Before deploying the sensors, I need to show details of ultrasonic sensors to the authorities from hospital. I can only use ultrasonic sensor that power emitted is not more than 1 mW. That' why I am so serious about this matter.
    But I know that this low freq device don't emit too much power, the only problem is I don't have any facts related to power emission from this device.

    Generally, do you have an idea about how much power emitted by devices operating at 40 KHz freq range?


    Regards,

    Aung
  • Bruce BatesBruce Bates Posts: 3,045
    edited 2005-09-26 00:55
    Aung -

    Now I think I see what they may want. I suspect they want the spurious radiation (EMI, etc) to be less than 1 mW, not the output of the transducer. The only real source of that sort of radiation (as far as I'm aware) is any resonator or crystal used for the microprocessor, and any local oscillators which may exist on the Ping PCB.

    I'm sure one of the hams on board will correct me if I'm wrong, but I think what you need to find is someone with a broad spectrum frequency analyzer. That should give you the spurious radiated power, as well as the frequencies where they occur.

    Regards,

    Bruce Bates
  • Ed StennieEd Stennie Posts: 18
    edited 2005-09-26 14:26
    Bruce is corrrect.· The hospital is concerned that radiated EMI may affect other medical equipment in the patients room.· I also believe that the hospital is interested in system compliance, that is compliance for your entire circuit design, rather device compliance, in this case the sensor.· This type of testing needs to be conducted at a licensed lab and that can be expensive.
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