A lot of hams like to carry a VHF radio. Of course, nearly everyone wants to carry a phone. Now, thanks to the kv4p HT, you don’t have to carry both. The open-source device connects to your Android smartphone and turns it into a radio transceiver. You can build it yourself for about $35. Check out the video below.
The device uses an ESP32 and only transmits one watt, but it has lots of features like APRS and scanning.
The brain is an ESP-WROOM-32. There’s also a ham radio “module” that is easily imported. The rest is fit, finish, and software. The PCB is fairly simple and inexpensive. A 3D-printed case completes things.
There is a new version of the PCB that hasn’t been tested as of this post, but the older version (1.5) seems to work ok, too, if you don’t want to risk trying the 1.6 version and you don’t want to wait.
We always marvel at how many building blocks you can get now. Grab a computer and a radio, and use your phone for power and a user interface. This would have been an enormous project to complete not long ago and now it is an hour’s time and $35. You’ll probably spend as much time ordering parts as building.
If your phone mostly trades cat memes, it fits right in with old ham tech. Just watch the antenna.
far out. a “ham radio module”. analog in, analog out, and a serial link with “AT” commands to select the frequency and filters.
i was really imagining a “RTL-SDR” sort of board with a wifi interface as an alternative to getting ‘usb otg’ to work (which has been done too, i guess)
Actually.. It’s not that bad, I think. If I understand correctly:
It’s a real 2m FM transceiver module with a clean signal and a programmable PLL.
An extra ESP32 provides an 1200 Baud KISS TNC that simulates a Hayes modem (AT command set).
It’s not fancy, maybe, but can be a rock-solid solution for APRS and Packet-Radio. Which still can be very interesting. Games are possible, too.
Pictures can be sent over APRS and conventional Packet-Radio, too.
There were/are lesser known experimental digi modes supporting this.
The MFJ TNCs supported live pictures via Packet-Radio, I remember.
And at least one high-altitude balloon project stored JPEG data in the comment/info space of APRS frames. SSDV?
Various games had existed in DOS days for Baycom modem (BayChess) and Graphic Packet (GP).
A modern implementation of such games or a DOSBox session can be used, maybe?
The smartphone is in the role of a Palm PDA or Pocket PC, essentially.
Both used to be popular in ham radio in the years before smartphones.
I mean, okay, an FM discriminator output for AFSK would be ideal in principle.
Not sure if it had one or if the audio output is going through an amp chip.
It’s not that important to most users, either, maybe.
The advantage in this concept is that the ESP32 is controlling the module, I assume.
Since it’s a separate microcontroller, the transceiver can’t get stuck in TX mode if Android hangs or crashs.:
A watchdog can be implemented in the ESP32, which turns off TX mode if a timeout is reached.
The project would also be useful for balloon projects or creating a digipeater, maybe. Where you need a little handheld computer.
I mean, there are so many potentional obsolete Android devices around..
Recycling them for a good purpose would make sense.
Even with a cracked screen or and outdated Android this would work.
And last but not least, a plug-on board as such is kinda cool!
Aeons ago, the Handspring Visor had a springboard slot, which also supported a cell phone module.
So the PalmOS PDA was turned into an early smartphone.
This project here is like an ham radio equivalent.
It might impress friends and other people interested in ham radio.
So cool I love it
It says it’s an open source project; has anyone been able to locate the schematics and the embedded source code? (The android app seems to be the only thing available on github)
Yes. It’s all available or at least linked in the Quickstart section on the authors website http://www.kv4p.com
I’ve already placed my PCBway order to get the ball rolling for making my own.