Need beginner help with RF 315MHz RX+TX pair..

[josephlcs]

Hello,

I bought the 315MHz RX TX pair from cytron, but I can't for the life of me get them to work.

At the moment I've connected the transmitter to Vcc (5V) and Gnd; for the antenna I used a (roughly) 24cm single core copper wire, and for the data I've put in a 40kHz square wave from an oscillator.

On the receiver side I've also connected to 5V and Gnd, and I've plugged the RX pin into an oscilloscope.

Now what do I do with the antenna for the receiver? I see only two holes, one marked "ATN" and the other "GND". Without anything connect to them I see a random square wave appearing on my output. I've tried touching the ATN pin with another 24cm wire, but nothing changes. I tried disconnecting the transmitter - same noisy sorta signals.

What seems to be the problem? How am I supposed to wire the antenna? Is these something wrong with my set up? Some help will be most appreciated. =)

Thanks.

[yonghui]

hi,

the receiver is regenerative, which when it doesnt receive any signal from the transmitter, it will pick any signal in the air,noises to amplify it. the amplification level is auto adjusted to get signal to output at the receiver, even small noises which is not signal, will be amplified. when a signal from transmitter is received, it will readjust the amplification level to the tx signal level and give the correct value. thus filtering is important. filter unwanted noise from being processed in the microcontroller. refer to the cytron DIY project for the way to do it


regards,
yh

[josephlcs]

Alright, that information will come in useful.

I'm still unsure how do I attach an antenna to the receiver. I stuck a 24cm wire in the "Ant" hole, but I left the "Gnd" hole (which is next to the ant hole) I left alone. Should I do something with that then?

[yonghui]

ya, shud be ok with just the wire connect to the ant. as the antenna. u have oscilloscope with u.
u can try this:

at transmitter side input a square wave of low frequency (mayb 100Hz to 1KHz since the maximum stable baud rate is around 1200bps, not sure) to the signal pin of the transmitter pin. and hook the oscilloscope probe to the output signal pin on receiver side. both transmitter and receiver need to be powered.

u repeatly connect the square wave signal and disconnect the square wave to the signal pin of the transmitter , see how the input square wave affect the output signal of the receiver.

u will notice that the absence of square signal will cause the noise being amplified as output, but if the square signal is present the receiver will have the square signal to be amplified as the output.



regards,
yh