Beacon transmitter/ Beacon receiver project

Discussion in 'The Projects Forum' started by Cris909, May 11, 2014.

  1. Cris909

    Thread Starter New Member

    May 4, 2014
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    Hello,

    I am working on a project and I need to create a beacon transmitter and a beacon receiver to receive the beacon. I need the beacon to transmit a continuous signal for a 1,000 ft radius, then I need the receiver to be able to receive that beacon when the beacon is within the 1,000 ft radius.
    Is the best way for me to go about this by using a specific RF signal as my "beacon" ??

    Where would be the best places for me to go for the things I need?*

    Any information, advice, input of any kind will be a great help.

    Thank you,
    Cris G
     
  2. GopherT

    AAC Fanatic!

    Nov 23, 2012
    5,991
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    Best would be a continuous RF signal where you can modulate an audio signal on top of the RF signal - like a radio works. that way, you can turn the beacon on and off while still assured that you are tuned into the "station" with your receiver.

    Or, you could look for answers on the 4 other new threads that you created on this topic today.
     
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  3. Little Ghostman

    Member

    Jan 1, 2014
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    Not much info so most of this is based on a few guesses I made.
    http://www.silabs.com/products/wireless/wirelessmcu/Pages/default.aspx

    What I would do

    Pick a wireless transmitter MCU and receiver MCU from the above link, the reason is I have used there stuff alot lately and its good, the wireless mcu's are good energy wise, that makes it possible to use energy harvesting and small battery for power system, you get full control over the transmitter frequency and channel, they have a software system that makes setting the whole thing up easy.
    You can define the payload and number of data packets etc, you can set up encryption easy. You didnt mention if its a continuous beacon or if you are going to say have it transmit every x seconds/mins, I would do every x seconds, this means if you choose the right energy harvesting system and use some super caps, you could probably get away without a battery on the transmitter, as you have full control on output power, then getting 1000' wont be too hard, it wont be exact though.
    One big advantage with sil labs is the software they give away free, you can use it to test range and signal strength etc, I have used there radio kits alot lately and found them easy to use and set up, they have been very energy efficient.
    I would be tempted to just by the EZ radio dev kit and use that, then you can walk around with the receiver and get the figures you need (signal strength etc) in order to set up the transmitter properly.
    If you think it will do what you want, then give me a shout. I have some of the dev kits here and would be willing to try a few things out for you, as long as I am not having my op of course

    Best Regards

    LG
     
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  4. Cris909

    Thread Starter New Member

    May 4, 2014
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    I checked out the website but I'm not sure which one fits my needs the most??
    Also what do you mean by dev kit and your willing to try a few things out?

    Another member gave me some advice and I would like to know what you think about this method. It's as follows..

    The simplest approach would be to use an op amp configured as an oscillator at an rf frequency, say 300kHz and have it drive an antenna which would consist of just a long wire. That's your transmitter. The receiver would be fed by another long-wire antenna and drive another op amp, this one configured as either an inverting or noninverting amplifier with its output feeding an LED in series with a small resistor.That's the simplest approach. If you need more power have the op amp transmitter feed a common emitter amplifier which in turn feeds the antenna. Try different antenna lengths. The wire can be small magnetic wire.
     
  5. Little Ghostman

    Member

    Jan 1, 2014
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    I have to be honest, when it comes to transmitting signals I like to be sure I am not causing others problems, unless you have a spectrum analyzer then I wouldnt be confident that I was not causing others a problem, but its entirely upto you.
    Can you tell us what the beacon is for etc?
    If its a dog collar type project then you would go one way, but if its something else?? It really helps if you tell as much as you can.
    All I meant about trying a few things out is I can do some experiments for you if you use any of the sil labs chips, I have several of there development kits, mine all run at 868KHz. I cant recommend a chip until I know what its actually for. If you need something doing upon beacon detection then it might be worth using one of there MCU's with TX/RX built in.
    Give us more details, I can always do some range test's etc for you, if you decide to use there stuff.
     
  6. Cris909

    Thread Starter New Member

    May 4, 2014
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    It's for school, and it is a dog collar project lol.
    There's nothing else I need it the transmitter to do just transmit a continuous beacon for 1,000 ft without interfering with anything else.I just need the receiver to be able to receive that beacon and light up a small LED when it's within range.
    The reason I say unique signal is because I don't want the receiver or the transmitter getting any interference from anything else.
    I hope this helps.
     
  7. THE_RB

    AAC Fanatic!

    Feb 11, 2008
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    It the range is 1000 feet in open air (like on flat ground with no obstacles) the range might be 100 feet once you get buildings in the way, and maybe 50 feet if the dog is tucked away in some shielded place like under a car or next to a car.

    You can't use a simple beacon to always signal if something is <1000 feet.

    Please say if it needs to indicate a <1000 foot distance, or if it is just a beacon that needs to work in a general 50-1000 foot range.
     
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  8. Cris909

    Thread Starter New Member

    May 4, 2014
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    It's a beacon that needs to work at 1,000ft or more. It needs to work at that distance under any condition.
     
  9. Little Ghostman

    Member

    Jan 1, 2014
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    I had a feeling it would be a dog collar, the 868MHz is used for smart meters like Gaas and Electric, they can be set to continuously transmit a signal, any collectors in the area then pick the signal up, if they have the address on there side they then send a command to read the meter.
    If the following guesses are correct then this should work, its based on something being done around where I live with sheep. Dad is involved hence why we have the wireless Development kits. Now if you substitute a sheep for a dog then the same system should work.
    The following is mostly me guessing your requirements and assumptions based on what I know works with the sheep system.

    The dog/sheep is outside

    The receiver to notify of sheep/dog in range is inside

    You want to know when the sheepdog is in range

    So

    You are better off with three elements, might as well go with 3 transceiver chips, you could do it with 2 and a receiver chip but cost wise is little point,
    Also because these were primarily developed for smart meters, the software to set them up, means you can be sure the collar only talks to you, the signal is encrypted and address based, its currently used to track 1000 sheep over 3KM.

    I would have main transmitter outside, *

    * Assumption here is a good power supply for this one, is doable another way if power is iffy

    Main transmitter sends a general call asking for nodes to respond, you could set this to send every 2-3 seconds or whatever you want, The good thing about this system is the power control, you could set the chip to send at say 20db, this with the outside one should get you around 3-4km, so it sends at X power, in its message it sends is the following.....

    Hi are there any collars out there? I am sending at X power, if you read this signal transmit back at X power with your address please.
    It waits (you decide mS or seconds or hours or whatever), if it hears nothing it sends again............and so on Until it gets a reply! then say it gets the reply at 20db (you have been around the perim before hand finding distance at different power ;) ), it then sends a signal at 20 db, saying same as before except, it asks the collar that replied before to send its address at 15db.
    The idea is you can track the distance this way, so eventually say it transmits at 2db and 2 db gives a distance outside of say 1000', as soon as it detects this is sends on the second channel to your receiver, your receiver then lights the led on your desk.
    The collars need only switch on and listen every 30 secs or so, that keeps the battery usage down, and it only transmits when it hears a signal that ask's it too.
    There is a bit more two it than outlined, but that is a rough idea how it works, the sheep one has been running since Christmas and works really really well.
    If you want to know more let me know, it wil be a long post so I wont post unless you really want it
    LG

    (BTW it was my design :D, my first ever paid for job :D:D I got £100 for it)
     
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  10. Cris909

    Thread Starter New Member

    May 4, 2014
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    Let me make sure I understand what your saying...
    Your suggesting 3 transceivers . One will be on the dog which is the transmitter, one will be on my desk which is the receiver, and the third transceiver which is the main one will be outside.
    Is the main transceiver that is outside able to work while moving or does it have to be stationary?
    Is there any way it could just be 2 total elements? Could the receiver with the light be mobile just like the transmitter on the dog?

    I like your idea and I would definitely like to know more.

    Thank you,
    Cris
     
  11. Little Ghostman

    Member

    Jan 1, 2014
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    You have it slightly wrong so I will explain, keep in mind I based it on the following.

    You had a dog collar (and a dog) it moves about.

    You wanted to guarantee that it would be picked up at a set distance (1000')

    The Led or buzzer or whatever would be inside

    First of all they are all micro's with a transceiver built inside of them, the micro controller part of the chip is based on a low power consuming 8051 processor.

    ALL units can send and receive messages .
    So why did I pick 3?
    I picked 3 because with one fixed outside, that gave you the required fixed distance of 1000', it also meant you could be flexible with its power, you could have it near enough to the building to have a plugged in supply, if you did that then you dont have to worry about the power it uses transmitting.
    The one inside was the one with the led, I chose that one because you could put it anywhere in the house at be pretty sure it would pick the signal up no problem.

    So in my original idea before you started wanting things to move, it works like this.

    Dog collar can send OR receive a signal, if your clever you could have used a rechargeable battery and special kind of flexible piezo strip called dura patch, this flexible patch could have been position on the collar in such a way that as the dog moves about, it charges the battery, these strip's would easily keep it charged! They are not cheap but they are excellent! Anyway the dogs collar is normally sleeping saving power.
    Once at a predetermined time (say every 5 seconds) you wake it up and get it to listen for say 3 seconds, if it hears nothing it goes back to sleep.

    The main Transceiver outside sends a signal every second (could be any amount smaller than collar), it sends this signal at the power level that can just about be picked up at your imaginary 1000' limit (or any distance you want within reason) The bigger the distance the more power needed to send the signal, although its only around 10mA at 10db (I think), and 10db should do 1000' (I will check with mine).

    The signal the outside one sends is encrypted and matched to the collar, in that signal you do something like an address (collar address), so the message from this outside one basically say's every second, hi collar (number whatever) can you hear me I am sending at 10 db, if you can hear me reply at 15db. (dont worry why the difference yet).
    If the dog and collar are inside the 1000' the collar will receive the signal when it wakes, as soon as it hears it's address it sets its power to 15db, and replies back to the outside station, something like. Hi I can hear you I am collar number (XXXX) I am trans at 15db, the outside station hears this, sends a message straight back saying, can you send again at 10db, if the collar hears it then it replies at 10db.
    This continues until the outside one cant hear it. That way with these chips your able to read the RSI and other parameters like signal strength, so as the collar sends lower power, the base station can estimate the distance to the collar.

    When the collar is at a range you set, then the outside one calls the other chip up on your desk, and it says HI the bloody dog is here again get your gun and flash a Led.

    This system was based on what you said.

    Now if you want two units

    Yes it can be done, the only small problem is, inside the house or building there will be places that it dosnt transmit as well, so the distance will be reduced, so a roof mounted fixed one, gave you a fixed point and known distance.
    But there is nothing to stop you having two units, it just means you have to be more careful setting up and you need to think carefully about the main units transmitting power, unless of course you can charge it up every day.

    That in a nutshell is roughly how it works, the sheep one is a bit more complex but works roughly the same way, the main differences are the main unit transmits over 69 channels, each channel has 10 addresses, also the tags on the sheep have been set up as a sort of mesh network system.
    You dont need any of that though, this is a trial for tracking and keeping watch on 500 hill sheep.

    So yes 2 units is possible, yes you can make both mobile, yes you can have more than one collar, yes you can have pretty good control on distance. And 868MHz means you can use a tiny antenna (I will post a pic of one).

    What exactly is it for? Why do you want to flash a led when the dog is inside 1000'?
    Do you like the dog?
    Is it a warning system?
    Is it a tracking system?

    OR

    You keep loosing your dog and want to find it? If thats the case, then you would probably want a very slightly different system, and use two channels and two antenna's, one to send on one channel and multi directional, and one to send and pick up on another, but is directional

    Stop making me guess! I get tired, just tell me all the details please.
     
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  12. Cris909

    Thread Starter New Member

    May 4, 2014
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    I understand what your saying now and I apologize if I haven't been clear. I will explain the real reason for my beacon.
    It is not for a school project. My wife and I have 3 kids, 2 in high school, 1 in college. All of them drive.

    Due to recent events that happened recently I wanted to put a small transceiver in each of their cars to act as a beacon.
    I wanted a small portable transceiver with an LED connected to it to light up when my kids are close to home so my wife and I have time to compose ourselves.. if you get my meaning.
    The reason I wanted the receiver to be portable is because my wife and I aren't always using the same room either.

    I hope I explained the details well enough.

    So yes I want it to be a warning system, hence why I assumed a beacon is what I'm looking for.

    I appreciate all your help so far.

    Thank you,
    Cris
     
    Last edited: May 14, 2014
  13. Little Ghostman

    Member

    Jan 1, 2014
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    It says I want to post 9 images!!! so I cant post
     
  14. Little Ghostman

    Member

    Jan 1, 2014
    294
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    Thats odd, I cant post what I wanted because the software says it has images attached (it dosnt)! I pmed you the info, give me a couple of days and I hope to have a demo sorted
     
  15. Bp_968

    New Member

    Dec 25, 2013
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    Why not a simple driveway alarm? Or just tell them to stay away for "x" period of time? I strongly suspect they have even less desire to interrupt you then you have of being interrupted ;)
     
  16. Cris909

    Thread Starter New Member

    May 4, 2014
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    Because I want to make a beacon. Any information on how I can do so would be a great help.
     
  17. Bp_968

    New Member

    Dec 25, 2013
    21
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    Maybe a simple transmitter (say a 434mhz or 900mhz) and have to sleep x time and wake up and send out some mega pulses and have a simple buzzer / ringer that buzzes/blinks colored lights and bounces around to announce the invaders impending arrival.

    You could go entirely in the other direction and build GPS trackers with a cell shield. Using the cell shield with prepay cards would allow you to keep those vehicles under 100% continuous survalence. You could setup a system like that pretty cheap even.. Probably less the 100$ a car even considering the SIM cards and the prepaid minutes. If it sends the data in emails or texts it could be pretty cellular airtime efficent.
     
  18. Cris909

    Thread Starter New Member

    May 4, 2014
    28
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    Do you know what Mhz can legally be used in California without a license?
     
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