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ronydc
Joined: 17 Nov 2005
Posts: 148
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 12 May 2009 12:08 transmitting audio 433mhz |
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dear friends.
i m doing a project on transmitting a temperature data ( in the form of voltage)
through readily available tx and rx. modules of 433mhz. pair.
my question is -- is the encoder and decoder chips are must at both the ends of rx and tx ..?
without the encoder can't i transmit the temperature data voltage comming out of the op-amp pins to the reciver and reciver can fed that to a microconteroller .?
In short i am stuch at the data trsnsmission point. my tx and rx have "data" pins available.. does that mean a "serial data " ..? i mist need to feed the serial data to the tx .?
please advise.. friends.
if some one have ckt diagrams related to this and if some one done the work previously in this area.
-- thanks in advance.
-- Awaiting rony
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FANT
Joined: 27 Feb 2002
Posts: 367
Helped: 12
Location: Italy
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12 May 2009 12:40 problém s aurel 433 |
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Usually such modules have the signal path AC coupled, in this case you cannot transmit a dc voltage. This is why they ask for data.
I know that some modules from Aurel are DC coupled, but foresee some noise on the DC coltage on the output of the receiver due to noise and disturbs.
Usually is better to encode the DC voltage and transmit it as a serial data.
Mandi
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vfone
Joined: 10 Oct 2001
Posts: 2327
Helped: 326
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12 May 2009 12:46 Re: 433 mhz rec and transmit problem |
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The simplest way to transmit a DC value over the air is to convert it into audio frequency which is modulating an RF carrier.
On the receive side you can use after the demodulator, an audio BPF or a tone decoder (e.g. NE567) to select the modulating frequency (which corresponds to the initial DC voltage).
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