help...encoder/decoder

decoder php lockit

hi, everyone !


well...i'm thinking of a system for a project. basically the idea goes like this: for the transmission part; it consists of RF Tx module, encoder and dip switch. the dip switch will set the transmitter address, rite ? this address has to match with the address of the decoder circuit at the Rx.

at the Rx, it will receive the data/signal from the Tx. if no error or unmatched address, the data/signal will be decoded by the decoder. the data will be filtered (what kind of noise filter actually could be used ?) & stabilized. then the data/signal will be used as the i/p (to the microcontroller) to trigger some control unit.

since my knowledge is limited on this, the questions are:

a)is it the encoder/decoder is for security only...in term of receiving only the correct signal & to prevent the interference of unwanting signal for the above situation ?

b)how bout the dip switch ? i'm kind of blur bout it.how it works actually...with the encoder/decoder..in term of the setting certain address for the signal (RF).

tq

encoder decoder signal

It is not clear what kind of encoder/decoder you are talking about. Are you thinking about remote for car door lock (it can use DIP switches for lock code setting)?

hoe to decode signal with decoder of ht12d

well...hehe......myself also not so sure....:|

Added after 8 minutes:


ok...

then, someone explain to me what's actually the purpose of encoder/decoder in RF transmission ?

and what's actually the application for dip switch ? maybe...u can relate to my above problem.

tq....really need help

well, just to add...

from what i know....the function of encoder and decoder are to prevent the stray signal of the same frequency. so that, the Rx will only receive the transmitted signal, not other signal of the same frequency. rite ?

so....what's the function of the dip switch in this matter ?

fhl:

from what i know....the function of encoder and decoder are to prevent the stray signal of the same frequency. so that, the Rx will only receive the transmitted signal, not other signal of the same frequency. rite ?

Click to expand...

right

so....what's the function of the dip switch in this matter ?

Click to expand...

The dip switch is used to generate the code for your signal
which should be same at both encoder and decoder side
If code is different the receiver wont recieve/decode the signal

check these links for encoder/decoder ICs and their applications (I am not sure if they are for RF transmission
**broken link removed**

Just to clarify. You can not encode RF the modulation is coded. Receiver receives any RF signal of the same frequency but only the right coded modulation signal will be allowed to reach receivers output. Purpouse of DIP swiches is to ease code setting. Receiver has DIP switches too because zhe receiver code must be the same as transmitter code. This is how it is done at simple RF remote controlle which is usually operating on 433MHz, depending of country regulations.
To say again RF can not be coded only modulation signal can be.

thanks


yup...only modulated signal can be encoded.
as the transmitted signal received by the Rx...it will be decoded by the decoder.

i would be glad if there's more u guys wanna tell me...bout the dip switch n encoder/decoder.tq

Coder and decoder pair can be Holtek HT12D and HT640. They both need DIP switch or jumpers for setting or ease change lock code. Code can be simply set allso by soldering appropriate contacts.

thanks for telling me about the IC HT12D . Since i haven't known it, i chose to program using C and avr MCU to encode and decode the RF signal. this task is quite challenging, i still havn't got a satisfied result due to noise
ht12d datasheet gives me a good hint to send 3 times the data; then, at the receiver terminal, compare them to the stored commands. anyway, this is not thourough, there is still a chance when all 3 received bytes are error; then data resending is required (unluckily, the user are not happy to press a button several times to set a command)
anyone can help, plz !