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.
Basically, any modern smartphone have several SDRs inside as baseband RF channels with frequency range from around 300MHz to 3GHz. Most basebands are just ARM cores with I/Q stuff analog interface and some hardware codecs for cellular modulations. So there is no need for any external hardware, it’s already in place, question is only in writing own firmware for baseband. F.e. two-way 433/868MHz amateur band walkie-talkie could be implemented only with software means right on smartphone hardware. The huge problem is that attempts to reverse engineer baseband firmware and break that highly proprietary things free are persecuted by corporations and regulators, several such projects for qualcomm basebands was quickly deleted from github as they appeared.
Only project of that kind that is somehow alive is Osmocom-BB, targeting TI Calypso-based and now very outdated phones. Guys was focused on implementing completely opensource GSM framework for mobile and base stations, and succeed, but their findings could be used for building ham radios too. IIRC there was some test examples in osmocom-bb sources that could be used to make basic walkie-talkie from regular mobile phones with Calypso. Some also trying to do the same with MTK SoCs, but it is far from completion and outdating fast due to very few developers.
It’s a pity that this potentially extremely powerful direction of ham radio development is barely known for DIY public and even kind of condemned by traditional ham crowd on the point of all that regulations and rules about mobile phones.
Phone baseband firmwares are locked down, and locked down hard. And for good reason. A flexible transceiver which is user configurable is utterly incompatible with device or class licensing. If you can’t absolutely guarantee that your device is incapable of operating outside it’s license, then it won’t be approved for sale.
Of course, you can license the user instead, but nobody is going to accept needing a license just to own or operate a phone.
That is why it must be hacked. :) We already have few examples that it is perfectly possible. And main problem is not even with decompiling and replacing firmware, it is mostly just ARM code, but in obtaining NDA documentation on baseband processor peripherals and their registers bits purpose or doing that by reverse engineering, which is time-consuming.
It is a problem only between cellphone manufacturers and regulators. Why should anybody here care about that for a bit? How could it be relevant to rise such arguments among hackers? Isn’t that the whole point of hacking – to make things we own to work outside their artificial limitations and initial purpose?
It is same as that inkjet printer cartridges with “protection” chip, “locking” car parts to force users pay loads to official dealer or other disgusting things manufacturers do. And there always some “good reason” when manufacturer limit our ownership rights. Smartphones are no different, and there can’t be any arguments about “good reason” for limiting our rights to use devices we own as we want.
How could it be relevant?
Being a hacker/maker/curious isn’t a license to break every rule, or make it trivial for any civilian to also break rules.
As always, it’s balance.
It doesn’t matter how careful or knowledgeable I think I am, I shouldn’t be allowed to buy a pallet of yellow cake Uranium to play with in my garage.
I’m also not allowed to perform surgery.
Or to call myself a lawyer.
Gatekeeping can be a VERY good thing.
Especially so when an inexperienced person can cause havock without understanding it.
I’d like it to be easier to get at baseband firmware, and it would be reasonable to have an option requiring licensing.
But a normie absolutely should not be allowed to have a one-click, web-flash, or even an easy cli option to modify baseband in any way.
@Ian
Oh, that “rules” thing…. Disgusting.
Like you don’t have decades of endless examples that most of that “rules” you praise are nothing but a way to make profit for some bastards. All necessary rules was figured out millenia ago and there is no any need for any other.
So, you never glue a wound with cyanoacrilate or cut out a splinter? Obviously you will prefer somebody die or be harmed a lot than to break some stupid “rule”. There is nothing special in surgery. It is exactly same as repairing broken things. Denying the right to fix yourself or beloved one, you also deny the right to repair fundamentally.
What? Are you living in some totalitarian society where lawyers are higher caste so nobody out of that caste could declare himself a lawyer? Are you kidding me? Even in Third Reich you had the right to declare yourself a lawyer and do all that lawyers stuff.
Every single “gatekeeper” I ever heard about always worked for some disgusting corporation or state. It’s not a things or actions that need to be “kept” from public, it is those who do bad things.
Banning knives or firearms does not save anybody. Killer will always find a way to kill, and only normal people will be harmed.
Same with all that stuff we talk about here. All that radio frequency regulations are only about profits of some greedy persons, and not about care or whatever virtue.
People have a right for a free (including as a beer), uncontrolled, and uncensored ways of communications. It is a basic right, because people communicate since the beginning of human race. No FCC or whatever corporation could take that right away or force you to pay for that.
There could be no any reason for that. Like there couldn’t be a reason to license breating in oxygen or breathing out CO2. You yourself emit some RF because you are alive. Fundamentally. When you allow some unknown and even unelected persons to license anything regarding RF, then they will inevitably end licensing your life. We already have that with CO2. Seems you want that with electrochemical processes in you too.
All that “regulations” in tech and around is nothing more than corporation/state attempt to control everyting. There is no any need for them, natural laws already resolved that millenia ago. Do everything you want, while it doesn’t harm others and be ready to be held accountable if you harmed somebody. It works perfectly with stick, stone, knife, chainsaw, whatever, why it have to be different with radiation?
Why? Normies don’t want even to abandon centralised social media or modern browsers, not even talking about proprietay OS or getting rid of car official dealer slavery. In no way they will want to do anything to get free communications. They love their slavery. Do you ever saw normie who use unlimited, unstoppable and uncontrolled Tox instead of centralized, censoring, spying WhatsApp on his phone? So your argument is senseless. There is no any need to keep normies from advanced possibilities their gadgets could potentially provide. They don’t need them, don’t want them and will never do anything to make their lives easier and more interesting.
This exactly.
So cool I love it
Agree!
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.
https://www.dorji.com/docs/data/DRA818V.pdf
this is the radio transceiver being paired with the esp32
(134-174mhz, has a mic pin and a spkr pin and some UART)
@Al Williams said: “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.”
Not so fast. I live in the USA, my current cellular provider is AT&T and they mandate a cell phone radio that is at least compatible with AT&T’s VoLTE specification. I doubt the radio module in the “kv4p HT” would simply comply with that. Or would it? The chances of the radio module in the “kv4p HT” working as a simple analog FM VHF and/or UHF amateur radio transceiver are better though.
Um, what? This is a VHF ham radio. It’s got nothing to do with the cellular network, and nobody has claimed such. You need an amateur radio license to legally use it, not AT&T’s permission.
Ah, thanks for that bit. I was wondering if I could make a couple of these for some family and friends, but it sounds like it would be legal to actually use them.
Well we could put an IMS gateway in the nearest repeater for you?
Interesting USB adapter, aliexpress have the same thing for a quarter of the price https://vi.aliexpress.com/item/1005005232638693.html
The world of 2m modules is interesting too, here’s a cheaper 3W one https://vi.aliexpress.com/item/32962803851.html
Great Job
This is very cool! My first thought while watching the texting back and forth was, “is there encryption?” Because that would be stinking cool. Secure wireless texting.
Amateur radio is open by design. Free of politics and commercial use.
Amateurs are self-policing and monitor their own transmissions, as well as that of others.
Amateur radio is both a hobby and a service. The driving forces are education, sports and research of wireless technology, such as measuring propagation on shortwave.
That’s why it has so many rights and bands.
It’s meant as a service to society as a whole, rather than providing benefits to few.
Not sure how encryption and secrecy fits into the picture.
Or to put this way, let’s think of the ‘no cloaking device’ rule of The United Federation of Planets in Star Trek.
The fictious contract of Algeron was meant to ensure peace, just like the rules of amateur radio do.
Amateur radio should never be abused for politics, for espionage or any kind of obufciation.
Believe it or not, the foundation of amateur radio was all about peace, international friendship and international understanding.
It was meant to build bridges, rather than rise distrust and secrecy.
And some of us do still believe in this, just like Star Trek fans believe in the principles of Star Trek and in a better humanity.
https://memory-alpha.fandom.com/wiki/Treaty_of_Algeron
https://en.wikipedia.org/wiki/Amateur_radio
https://www.jpole-antenna.com/about-2/the-amateurs-code/
I’m building one. got the PCB board, everything fits right except the esp32. The pins are too far apart from the left side of the chip to the right. the pins are roughly 22mm apart, the board is approximately 25mm apart. is there a different esp32 I can order. I have several differ3ent types and none fit.