About Radio transmission link

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Dear All,

 I am building up a radio transmission link with 4 bits digital input
signal(around 50-100Hz).  I have got two RF modules which are 315Mhz radio
transmitter and recevicer in 8kbps data rate. Also HT12E(encoder) and HT12D
(decoder) have been used as well.

The circuit is working by inputting a 5V/0V (connect to 5V with switches)
and outputting with LEDs. However, when I connected the input to the signal
generator (input 10-100Hz square wave signal with 4.5V amplitude) and
dectected the ouput with CRO, it doesn't work. Nothing can be outputted by
the CRO.  The connection is shown as the attachment. I am trying to send one
bit as testing.

Please kindly help me to solve the problem. Do I connect it in a wrong way
or is there any problem in the design? Thanks for your help.

Regards,
Lok




Re: About Radio transmission link


Hi,
the HT12E and D are not really made for this form of data transmission
however try the following, try using synchronous data by using the /TE
input. This should restart the transmit data process to use the new data of
the D8-D11 pins.


ie

TE _____/-----\_____/-----\_____/-----\_____/-----\_____

D8 _______/-----\_______________/-----\___________
to
D11

D8 input = D8 output = 101

Data is valid on the the falling edge of  /TE

Alternatively, only clock the /TE input when data on the inputs changes
rather than use a continuous clock.

Hope that helps
Greg



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Re: About Radio transmission link


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either you've got a sync problem or are using the wrong font.
I see the second pulse on D8  exactly synchronised with TE.
use courier, console, ocr-b, or some other monospaced font for these
diagrams.


--

Bye.
   Jasen

Re: About Radio transmission link


Thx

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Re: About Radio transmission link


Sorry, photo can not be uploaded.



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