PixelRadio, a DiY FM Transmitter with RDS RadioText

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ThomasLED

Member
Announcing PixelRadio, a DiY FM Transmitter for personal holiday lighting events. It's a low power radio that can broadcast mono / stereo analog audio and it supports RDS (RadioText).

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What is RDS? When your drive-by visitors tune into the show's music their automobile's infotainment display will show RadioText messages. The RDS can provide information about the music (artist / song name), hours of operation, charity donation instructions, and much more.

This is not a commercial product. It's a personal project that has been expanded for wider appeal to the pixel community. Initially I only planned to send a couple different canned messages that were important to me. But the final design includes a variety of features that should be useful to most pixel enthusiast.

PixelRadio is a WiFi appliance. That is to say, operation is through a web interface via a smartphone or desktop. A dedicated app is not used and most modern browsers should work. It is NOT cloud based, access only requires the local LAN.

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Keep in mind that this is a DiY project. I do NOT intend to make & sell them (my spare time is limited). Plus I'm aware that very few pixel hobbyist have the experience to reproduce the project. But some of you enjoy building such things. And perhaps the community can work together to make it more accessible to those with less experience.

The full project has been uploaded to my GitHub repository. You're invited to stop by and learn more about the project.
https://github.com/thomastech/PixelRadio

- Thomas
 
I only did a quick scan of your project so I may not be asking the right questions here -- and for that, I apologize.

How do you create the sub-carrier frequency for RDS? Normally the RDS text is injected into the hardware just prior to the transmitter's output section. I didn't see any mention about the transmitting hardware you're using for both the FM frequency audio and RDS sub-carrier. Or is this a complete software-synthesized FM system using a Pi?
 
No Pi needed. To keep cost low it uses an ESP32 for WiFi connectivity and a QN8027 single-chip stereo FM transmitter module. The FM chip provides digital-synthesized RF functions, including RDS. Its native RF power output is extremely low so PixelRadio has it's own RF amp to achieve a useful distance (100 meters on simple telescoping whip).

*EVERYTHING* is disclosed on the Github site. Schematics, source code, PCB Gerbers, bill-of-materials, and so on.

- Thomas
 
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Thomas,

May I respectfully suggest you post this over on the Green Site as well? I think there would be some interest there too!

This looks like a great project and while I am considering building 1 or two, I wonder if this might be something that could be facilitated by a resurrection of the Group Buy concept to bring down the cost of building them? Just a thought.
 
Hi TomL8345,

In regards to spreading the word to other forums, I prefer to keep it low key until there's been some early adopter builds. Feedback will help iron out any issues.

An organized group buy would be helpful, so maybe someone will do such a thing. In the meantime I have a very small number of blank PCB's (no components) for those in the USA that are highly motivated to build their own PixelRadio. Not free, but very low cost. /* Contact me privately if you are interested in a blank board and we can work out the details. */

EDIT: All my spare PCB's have gone to project builders, so I'm no longer able to help out. But a PixelRadio project builder has commented that he ordered PCB's from JLCPCB for only $7.

- Thomas
 
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TomL8345 said:
Thomas,

May I respectfully suggest you post this over on the Green Site as well? I think there would be some interest there too!

This looks like a great project and while I am considering building 1 or two, I wonder if this might be something that could be facilitated by a resurrection of the Group Buy concept to bring down the cost of building them? Just a thought.
Click to expand...

Ahh,I remember the group buy days. I would all in for it if it's done.
 
ThomasLED said:
No Pi needed. To keep cost low it uses an ESP32 for WiFi connectivity and a QN8027 single-chip stereo FM transmitter module. The FM chip provides digital-synthesized RF functions, including RDS. Its native RF power output is extremely low so PixelRadio has it's own RF amp to achieve a useful distance (100 meters on simple telescoping whip).

*EVERYTHING* is disclosed on the Github site. Schematics, source code, PCB Gerbers, bill-of-materials, and so on.

- Thomas
Click to expand...

Very, VERY clever and elegant! Hope you get some takers on this very fine DIY project!!!
 
Hope you get some takers on this very fine DIY project!!!
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+1. It would be great to have others enjoy it too. So far I've heard from three guys that are preparing to build it. Hopefully they come back and share their building experience, either here or at the project's Github site.

- Thomas
 
Is there a reason using Qn8027 vs SI4713
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I used a QN8027 based transmitter last year and was satisfied with its performance. I am familiar with the SI4713, but the QN8027 got the gig in my project.

... could have an adaptor to use on rpi and xLights/WiFi interface with your design.
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Yes, could have done that. I didn't want to use a RPI, I prefer the ESP32.

Keep in mind that this was a personal project. So design decisions were my own. Developer's choice, as they say.

PixelRadio is an open source project. So if someone wants to use the SI4713 then all they have to do update the schematic and change the code. The beauty of open source is you can use it as-is, or break it open and take the things you like and use them in your own spinoff.

- Thomas
 
This is really cool. With a HTTP API it should be pretty easy to write a FPP plugin to set the RDS data. Thanks for sharing!
 
I like "Building Things". I have looked over your gethub page and I'm impressed with this project. I have not taken the time to add it all up but rough guess how much to build 1? I'm fine with sourcing parts through AliExpress but that means maybe 2 to 3 months for delivery. It may take a while to get builds and feedback. I'd build one!
 
I have not taken the time to add it all up but rough guess how much to build 1?
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Wild guess is about $50. Add another $10 if you use the recommended extruded aluminum case. But I could be wrong -- Let's see what the other builders say.

FWIW, I spent over $500 to develop it. But I evaluated different hardware, spun two board revisions, and bought a lot of parts that didn't make it into the final release. So that's why I'm not an expert on what it costs. But I am a satisfied user. :)

- Thomas
 
Some of the parts I am looking at from Aliexpress have an ETA of 6/08.
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I'm in the USA and I'd say 90% of the parts arrived in 4 weeks. Some showed up in 3 weeks and the slow pokes took 6 weeks.

I eventually learned that it helps to order everything at the same time (one transaction). The AliExpress fulfillment warehouse will combine the separately labeled shipments into one parcel bag that is delivered a bit faster.

- Thomas
 
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I just finished ordering the parts to populate 2 PCB's including the enclosures. I spent a total of $99.88 including shipping and taxes.

I plan on building 1 to use and the 2nd as a spare. I will report on my build experience once all the parts arrive.
 
What source did you guys use for your parts? US-based, or Alibaba/Aliexpress?

Edit: silly me...I just saw the list from Aliexpress listed lower on the Github parts list page. :razz:
 
Many of the resistors and capacitors I just purchased are in quantites greater than I need. I would be happy to share once they arrive (in June :) )
 
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