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can u help me on RF based identification system?

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mailboy

New Member
hi,
im doing an electronics&comm project as part of my curriculum.
im thinking of an announcer system to be placed in bus stations which
receives a particular code transmitted from a bus and announces to the passengers about its arrival.
Is RF is a good choice 4 transmission ??RF has better coverage than
IR doesnt it? :?:
also there r 2 ways i thought 4 code tranmission
1)DTMF signals - is simple but only few capabilities (no: of buses) :?

2)Digital transmission-of course more complex,also needing a uC
but anyway im planning to implement it without a PC by using a uC :?



so have any of u got anything that could help me out ???
bye!!
8)
 

Johnson777717

New Member
RF would be better than IR in this case, unless you're talking about close proximity, or an extremely concentrated IR beam. IR can be drown out and distorted by the sunlight, objects in the way, and other IR sources.
 
RF is the way...

RF is a better idea then IR, no line of sight and less interference problems .

There are certain things you need to consider for this though. If the buses are signalling at the same time there'll be collision and the RF signal will be uselsess. You need to work out a protocol.

A simple anti collision method is to have the buses responding within their own time window. This would be relative to a signal sent by the "base unit" (the one fixed in the bus depot). if the base unit polled the area in this way every twenty or so seconds that eould be plenty of time to give several hundred buses their own response window.

you can buy simple radio transceiver module. BiM 433.9 is an example. check out the radiometrix website for details. You'd have to use a uC but you said you wouldn't mind so...

good luck :D
 

mailboy

New Member
thnx but..

hey,
thnx for the replies man i discussed the possibilities of implementing this
with a couple of teachers who have a good idea of practical electronics
and amazingly they came up with the same idea as urs ie. pulsed transmission where each bus will respond relative to a base signal.
its really amazing how u managed to came up with the same stuff as those pros in the subject.
any way thnx but could u specify the site more clearly which talked abt
radiometrix and RF modules ??
thnx again
 
The site is:

http://www.radiometrix.com/

Look for the BiM 418-40 or 433-40, identical in operation apart from the carrier frequency. Check RF regulations for your government to see which frequencies are "free" to use for these applications. Both of these devices are type approved for the UK and the 433-40 for Europe.

I'm working on something very similar employing these techniques for a person identification and tracking system at the moment, and these modules are working well.

I'm using a PIC 16F627 to control the BiM module on both sides (user and base unit) and on the base unit side it's multiplexed with the serial port of my computer for data logging and profile alteration.

Hope you get on well with it :lol: [/url]
 

mailboy

New Member
sure thnx

hey
thnx man
ur suggestions r very welcome indeed .
I think im gonna keep in touch with u ,if u dont mind!
and best of luck to ur project :)
 
no problem mailboy. Have a look at Nigel's Pic tutorials
www.winpicprog.com , they're a HUGE help with all things Pic.

I'm working on those and trying to Crack Visual Basic as well at the moment. :shock:

Feel free to e-mail me :wink:

Mark
 
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