Sos need help with project topic proximity indicator

Discussion in 'The Projects Forum' started by denisdaniel, Oct 12, 2011.

  1. denisdaniel

    Thread Starter New Member

    Oct 12, 2011
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    SOS NEED HELP WITH PROJECT

    Proximity Indicator - The aim of this project is to design, construct and test an electronic communication system which alerts a user of forgotten or left behind items, objects, etc. The system is based on FSK coding and decoding and FM modulation and demodulation theory. The alerting range should be within few meters

    AM PLANING ON USING AN ALTRASONIC FREQUENCY LIKE A PIEZOELECTRIC USING piezoelectric quartz crystal …
    VERY :confused:
     
  2. iONic

    AAC Fanatic!

    Nov 16, 2007
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    What have you done so far? Do you have any schematic drawings...etc?
     
  3. denisdaniel

    Thread Starter New Member

    Oct 12, 2011
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    yes i do have a black diagram am starting with first generating my ultrasonic frequency using a NE555 then will modulate using an LM565 and encode the modulated frequency .I will then use a power amplifer but not yet sure about the power amplifer then use a ultrasonic senor to transmit at the reciever i will do the opposite as u might know first demodulate and decode using the same chip i used already but just inter changing the pin and then use an frequency to voltage coverter which might be a pizoelectric ceramic to generate a voltage and a comparator will be connected between my micro vibrator the vibrator will act as the reference voltage which will be pull up to provide enough power to the vibrator when the signal from the transmitter is cut off.
     
  4. denisdaniel

    Thread Starter New Member

    Oct 12, 2011
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    need help i am designing a proximity indicator using an encoder HT12E with a T5-434 transmitter and a decoder HT12D with a R5-434 reciever the only problem is that i don't know how to reduce the distance to be a few meter cause the project requires a distance of few meters but i am still transmitting and recieving above 500meter help needed.
     
  5. praondevou

    AAC Fanatic!

    Jul 9, 2011
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    What antenna are u using for the RF? You should be able to obtain a much lower range if you detune the antenna (use an inappropriate length for example).
     
  6. denisdaniel

    Thread Starter New Member

    Oct 12, 2011
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    thanks for the quick response even when i do use a piece of wire or t do not even attached an antenna to it the distance is still to far i just want it less than a 100 meters so the alerting device can trigger off i have attached the schematic of my proximity indicator if you can please let me know how 2 reduce the transmission link.
     
  7. praondevou

    AAC Fanatic!

    Jul 9, 2011
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    Even without antenna you get more than 100m? That's incredible!

    How about using the RSSI output, it could give you an approximate idea of the distance.
     
  8. PaulEE

    Member

    Dec 23, 2011
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    I worked on a project similar to this three months last year.

    There was a base and a moving object. The base beamed a radio trigger signal to the object, and the object pulsed an ultrasonic sound wave to the base. The base timed the time-of-flight of the sound wave and calculated distance.

    Some things to consider:
    -ultrasonic transmitters/receivers tend to be directional
    -noise can set off an ultrasonic receiver
    -the surface you're on will totally skew the RSSI figure you think you can count on

    Good luck
     
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