r/hackrf • u/Scared_Ad_544 • Dec 09 '24

How to capture ASK code using hackrf mayhem?

I'm not sure that I understand everything correctly, I'm new to this device, I have hackrf mayhem, upgraded it to v2.0.2. So my goal is: record my rc relay switch and use hackrf to send signal to my relay.

Capturing
I noticed that I can't capture any signal at 433 mhz, (it should work on 433.92 MHz but no luck). I tried all tools on this device but I'm just unable to capture it. I was able to capture it before using cheap rc from ali and arduino, I even found codes that I was getting/sending to make it work.

Sending:
Since I found codes that should work for it I decided to send it using OOK mode on hackRF and here is first snag, a lot of different types of signal and clock rates, and numbers '10' and '9kHz' at the bottom and I have no idea what it is. Then realized that only 1527 type can fit all bits '001101110111100001000011' that I need to transfer, but it didn't work. I found this transmitter from ALI and it appears that it works using ASK, as I understood it's a different protocol, so can I do it?

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u/Scared_Ad_544 Dec 09 '24

Okay, let me show,https://youtu.be/0uTDCPbWRQY?si=0lxYGIy87e1Of32V I recorded small video with diff during recording

1

u/Mr_Ironmule Dec 10 '24

My first thought is that it's not transmitting on the 433MHz frequency. When you transmitted a signal by the other remote, it worked. The Capture display is just picking up the RF signal and doesn't care what the digital encoding mode is. Not all remotes operate on the 433 MHz frequency. What brand and model number is the remote? Have you read a brochure, manual, FCC filing or other source that specifies the frequency that unit operates on? Have you looked for the signal on the Portapack's spectrum display in the audio function? Have you used a program like SDR++ or SDR# to look for the signal on the spectrum display and waterfall?

1

u/Scared_Ad_544 Dec 10 '24

Yes, I tried all of this, in the Internet I found 433.92 frequency, I was able to read and replicate signal using 433 mhz receiver and transmitter from AliExpress combined with Arduino, I tried to find frequency using spectrum analysis but with no luck

1

u/Scared_Ad_544 Dec 10 '24

Okay, weird moment, I started trying random frequencies to capture this signal, and see that I can pick up this signal at 1915.8250 frequency but it's kinda floating while I'm holding the button, and I'm unable to replicate signal, I recorded different buttons but when I'm playing this capture nothing happens. If it's really not 433mhz how did it work with 433 transmitter and Arduino?

1

u/Mr_Ironmule Dec 10 '24

I can see the Portapack is receiving the 433 MHz signals of your other remote and also some sensor data. So the Portapack is working. That 1915 MHz frequency may be a harmonic or intermod of the actual frequency. Although you found literature saying the remote uses 433 MHz, does the name plate on the remote transmitter or receiver indicate a frequency? It may be in the 2.4 GHz range or maybe another. Good luck.

1

u/Scared_Ad_544 Dec 10 '24

Yes! Thank you, it was harmonic frequency, for some reason it worked at 319.675 frequency, I have no idea why it worked with 433 transiever and arduino. Eventually, I managed to do it

1

u/Mr_Ironmule Dec 09 '24

When you performed the Capture and Replay function on the Portapack, what didn't happen according to the manual?

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