6 ms·
Abusing RPi GPIO pins as a radio controller
- rnk 4y agoThat was a fun video, easy intro to analyzing wireless remote control signals with simple, almost free software.
- londons_explore 4y ago> Some people wanted to know if this is doable with an Arduino. The Arduino simply can't toggle its digital out fast enough to transmit at this frequency There is no need to be able to toggle a pin fast enough to be able to transmit at a given frequency. You can rely on the harmonics to get you to a much higher frequency than your code is toggling the pins.
- Johnythree 4y agoWhich means the output will be lousy with harmonics and intermodulation. Even a tight band-pass filter won't clean up the mess.
- jacquesm 4y agoIt will be anyway. To create clean RF isn't all that simple.
- wedowhatwedo 4y agoIt isn't simple if you use the wrong tools for the job. It can be simple if you don't generate square waves. http://ok1ike.c-a-v.com/gnat_40.pdf http://ok1ike.c-a-v.com/gnat_40.pdf There are 100's of similar simple circuits that generate RF that is clean enough.
- jacquesm 4y agoRight up until you hook up that spectrum analyzer...
- Johnythree 4y agoHave a read of any of the Amateur Radio books and magazines over the past hundred years or so. There are no shortage of simple Analog transmitters which meet FCC specs.
- dcanelhas 4y agoI was thinking "oh wasn't there a project a few years ago that also used the GPIO pins to broadcast FM radio?". Turns out those few years were almost a decade: https://hackaday.com/2012/12/10/transmit-fm-using-raspberry-pi-and-no-additional-hardware/ https://hackaday.com/2012/12/10/transmit-fm-using-raspberry-...
- stavros 4y agoYeah, I remember transmitting the then-current hit, Rihanna's Umbrella :(
- genericacct 4y agorpitx is probably the #1 reason for getting a raspi these days. If you can find one that's not marked up 200%..
- ale42 4y agoThis kind of things will never get FCC approval ;-) I would be curious to see the spectrum around the transmitter on a spectrum analyzer :-)
- sokoloff 4y agoI enjoyed reading about the programming and testing of a kickstarter project that used this technique in their fixed-frequency public radio receiver: https://www.kickstarter.com/projects/centerlinelabs/kickstarter-gold-the-public-radio-the-single-stati/posts/1982192 https://www.kickstarter.com/projects/centerlinelabs/kickstar...
- fortran77 4y agoWith a proper low-pass filter, the RF will be fine. I have a "WSPR" beacon going all the time that is heard around the world -- from Antarctica to Europe to Japan to Russia. The RF is generated from an I/O pin, low-pass filtered, and amplified to 200mw which is a common power level for WSPR.