user71617: I have this 433 mhz transmitter and receiver for arduino.

I want to replay my garage door remote control with this transmitter so I reversed the RC (remote control) signal with RTL-SDR/sdrsharp and audacity.
It is not working.

Why is there a shift between the carrier frequency of the signal transmitted with arduino (RH_ASK library) and my garage door RC ?
How can I change this ?

user23644: Are you certain about what modulation is used by your garage door?
There are relatively strong side bands on 433.800 MHz. While most of the signal is at 433.900 MHz this might be an FSK variant instead of ASK modulated signal. In that case you will not be able to use this transmitter for your task. Usually taking apart your remote and searching for the IC numbers will give you more insight about what is being used. If you find an FCC-ID on your remote, you can try to find information that way as well.

user69592: The reason is that your garage door opening is operating on a different carrier frequency than your transmitter module.  The plot you are showing is called a "waterfall" plot and shows the frequency on the "x" axis with time progressing from top-to-bottom.
The garage door remote appears to be centered just above 433.900 MHz while your transmitter is around 434.000 MHz.  While that might not seem like a large difference, these things are designed to be receptive in a very narrow band.
So you need to read the specifications of your transmitter module and see if its frequency is adjustable and, if so, adjust it upward to the correct frequency.

71617: <p>I have this 433 mhz transmitter and receiver for arduino.
<a href="https://i.stack.imgur.com/IoaFF.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/IoaFF.jpg" alt="enter image description here" /></a></p>
<p>I want to replay my garage door remote control with this transmitter so I reversed the RC (remote control) signal with RTL-SDR/sdrsharp and audacity.
It is not working.</p>
<p><a href="https://i.stack.imgur.com/mhp78.jpg" rel="nofollow noreferrer"><img src="https://i.stack.imgur.com/mhp78.jpg" alt="enter image description here" /></a></p>
<p>Why is there a shift between the carrier frequency of the signal transmitted with arduino (RH_ASK library) and my garage door RC ?</p>
<p>How can I change this ?</p>
 23644: <p>Are you certain about what modulation is used by your garage door?<br />
There are relatively strong side bands on 433.800 MHz. While most of the signal is at 433.900 MHz this might be an FSK variant instead of ASK modulated signal. In that case you will not be able to use this transmitter for your task. Usually taking apart your remote and searching for the IC numbers will give you more insight about what is being used. If you find an FCC-ID on your remote, you can try to find information that way as well.</p>
 69592: <p>The reason is that your garage door opening is operating on a different carrier frequency than your transmitter module.  The plot you are showing is called a &quot;waterfall&quot; plot and shows the frequency on the &quot;x&quot; axis with time progressing from top-to-bottom.</p>
<p>The garage door remote appears to be centered just above 433.900 MHz while your transmitter is around 434.000 MHz.  While that might not seem like a large difference, these things are designed to be receptive in a very narrow band.</p>
<p>So you need to read the specifications of your transmitter module and see if its frequency is adjustable and, if so, adjust it upward to the correct frequency.</p>
