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Kv4p HT – A homebrew 1W radio (VHF or UHF) that plugs into an Android phone
- RobotToaster 5mo ago1w seems a little limited? A cheap baofeng is 8w.
- lormayna 5mo agoOnly on the paper, the real power is around 3/3.5W
- takipsizad 5mo ago1w is usually okay and using 8w from a phone is probably way too much power demand
- Kaliboy 5mo agoThose cheap baofeng's are illegal to use where I live on most of the spectrum they can operate on. Illegal to press the talk button anyway. So maybe the 1w is also a regulatory issue.
- asdff 5mo agoHow does the FCC enforce this sort of thing? Are they listening in to certain frequencies nationally with the ability to triangulate a handheld down to actually identifying someone?
- l23k4 5mo agoUnless you're going out of your way to force them to react, they do not.
- martheen 5mo agoSomeone complained, they send someone to check and triangulate, verify that the operator doesn't have the license, then issue a warning or fine.
- deleted 5mo ago[deleted]
- asdff 5mo agoI wonder how close they can triangulate? I'd guess they are SOL if I am in an apartment building with 200 other units.
- martheen 5mo agoI mean, if you're deliberately being a dick about it, they will ask for a warrant and have the LEO accompanying them while triangulating, they can easily figure out which unit and even room you're in by walking around in the building with directional receiver. But in general, yeah, unless you do it regularly, living near sensitive facilities (airport, military base, hospital, factories, research labs etc) or deliberately transmitting at/near emergency frequencies (police, paramedic etc) at most you'll get yelled by a pissed off operator (at that point, stop, they could be already coordinating with someone else to triangulate you)
- fodmap 5mo agoMost of the time they get a complaint, and they investigate. https://www.fcc.gov/reports-research/guides/fcc-enforcement-bureau-broadcasters-guide https://www.fcc.gov/reports-research/guides/fcc-enforcement-...
- asdff 5mo agoWow, you mail them the complaint? No reason to worry about accidentally hitting the talk button I guess. Probably nothing happening unless you spam the frequency for weeks I'd guess.
- mystraline 5mo agoYes, weeks if its cell or GPS. Months or never otherwise.
- Bender 5mo agoThey mostly don't. They send scary letters and maybe eventually fine someone. They have a handful of triangulation vans for the entire US. The barely respond to complaints that are revenue impacting and generally don't respond to complaints from hams that a non ham is using their equipment. Once a quarter they make an example of someone so that it appears they enforce things. The people they make examples of are usually trying really hard to troll them or doing something highly disruptive and these will end up on a few websites and magazines. People tinkering and staying away from ham bands will generally be fine and for the cheap ham gear that made easy by design usually by doing a factory reset or worst case having to clip a diode to widen their frequency ranges. Most ham gear is designed to be highly hackable.
- gh02t 5mo agoYou only really get attention from the FCC if you interfere with some other service, especially broadcast or emergency communications frequencies. Grumpy Hams will also hunt you down sometimes, but only if you're persistent. Otherwise yeah, the FCC can't practically enforce every rule everywhere and doesn't really try. Still, get a license and be a good citizen if you want to play with this kind of thing, it's not very difficult.
- Bender 5mo agoAgreed. One youtuber [1] calls them Sad Hams. That has stuck with me. Linked video is the FCC's recent enforcement actions. I personally find some ham gear to be slightly less sloppy 11 meter rigs and a number of others agree. [1] - https://www.youtube.com/watch?v=QeMjMlHpus8 https://www.youtube.com/watch?v=QeMjMlHpus8
- souterrain 5mo agoIn the US all transmitting at 1W with these radios is contrary to regulations. That said, no one is going to stop you from squatting on 146.580 MHz for example, a frequency commonly used by outdoors folks, rules notwithstanding.
- ac29 5mo ago> In the US all transmitting at 1W with these radios is contrary to regulations. With a ham license the limit is 1.5kW, without one its zero
- Crunchified 5mo agoThis doesn't turn your phone into a ham transceiver at all. It turns your phone into a transceiver controller. Given that a cell phone is a transceiver, this headline is rather disappointing clickbait.
- alexwwang 5mo agoAgree. We need a compact short wave transceiver device actually.
- _whiteCaps_ 5mo agoThere's the trusdx or the QMX.
- FabCH 5mo agoBaofeng is 20 dollars? How much cheaper and compact do you need? And I know, I know, Baofengs are notorious for going over the allowed noise limits… but still…
- takipsizad 5mo agoBaofeng's are not shortwave radios afaik
- alexwwang 5mo agoyes. it's a good choice for light use in UHF/VHF scenarios even communicating to satellites if you have a Yagi antenna.
- jimnotgym 5mo agoBaofengs also have terrible receive filtering. It is perfectly possible to hear no stations because you are being overloaded by something on another frequency. I tried my first SOTA activation with a Boafeng. A transmitter on another hill meant I received nothing, although stains could hear me. By a Yaesu, still cheap
- 5mo ago
- s03nk3 5mo agoIs it so difficult to have schematics and pcb exported as PDF so that people do not need to fire up KiCAD to view the stuff?
- mk_stjames 5mo agoI encounter this problem as well when looking at projects on Github on a near daily basis it seems. It just led me to finding this: https://kicanvas.org/ https://kicanvas.org/ worth a bookmark.
- Retr0id 5mo agoOr even a picture of the physical device! I found some on a linked sales listing: https://chelegance.com/products/kv4p-ht-plugplay-vhf-radio1-7b/ https://chelegance.com/products/kv4p-ht-plugplay-vhf-radio1-...
- wolvoleo 5mo agoThanks! I was looking for that. I see they use those cheapo Chinese RF modules (SA818). I've seen those also with SDR input/output, that's interesting. The underlying chip is very similar: The chip that will be used in this module is the RDA1846. This is a chip that's in most Chinese handhelds and is internally fully SDR but it decodes to analog. There's also the RDA1847 with similar pinout which offers the raw SDR stream and can thus be used for any mode, but with the added complexity of having to do the SDR decoding externally. That means that this design could probably also be modified to do DMR. Though the SDR side might be a little bit too much to ask of an ESP32. On the other hand, it is only a very low bitrate signal.
- oslem 5mo agoSounds like a great contribution you could make!
- vitally3643 5mo agoThere are like six ways to export PDFs from KiCad. Project owners choose not to.
- bdavbdav 5mo agoI used to use SDR for DAB radio in the nexus 7 in the dash of my BMW E46. It didn’t work very well but was closer to being some kind of radio receiver (not trans at least)
- landgenoot 5mo ago> 1 watt transmit can go miles yet sips your phone’s battery How far can such a device reach in a typical urban environment with the longer antenna?
- fodmap 5mo agoYou can extend the reach using repeaters. This free app is handy for that https://hearham.com/repeaters https://hearham.com/repeaters
- lxgr 5mo agoVHF is effectively line-of-sight, and no antenna size can change that (although it does improve efficiency for both sending and receiving), so for two handheld radios, you are limited to about 10 km. The only thing that really helps extend the range is elevating the antenna, and repeaters allow you to do that even between two mobile stations.
- ac29 5mo agoVHF doesnt need line of sight, it has excellent ability to penetrate obstructions due to its long wavelength. For example, its not difficult to receive FM radio transmissions indoors, even from tens of km away. Some obstacles will effectively block any radio signal though, such as solid earth or concrete (esp rebar reinforced concrete). You are right that handheld radios wont get more than about 10km, but that is due to the curvature of the earth. Mountain top to mountain top, you could easily do 50-100km
- lxgr 5mo agoThat's what I meant by "effectively": Reflections, diffraction, and (moderate, i.e. think doors and windows, not walls) light obstacle penetration make some indoor reception possible, but the radio horizon remains the strong limiting factor. That's even true for the L- and S-band; otherwise you wouldn't be able to use a cell phone in a windowless room, for example. (Much of what's commonly attributed to "object penetration" is actually mostly due to reflections and diffraction around obstacles.)
- HelloUsername 5mo agoPrevious discussion on 14-oct-2024 https://news.ycombinator.com/item?id=41818609 https://news.ycombinator.com/item?id=41818609 191 comments
- tamimio 5mo agoI loved it, amazing work, thanks for sharing it!
- Melatonic 5mo agoIs it still worth it to mess around with older full duplex handhelds ?
- gh02t 5mo agoAnalog handhelds are still abundant, they've gotten smaller and more efficient but older ones are still basically just as good as new. IMO digital handhelds are superior, but digital protocols are much more fragmented so analog remains king as a common denominator (practically every digital handheld can do analog, too).
- mashijian 5mo ago[flagged]
- mystraline 5mo ago[flagged]
- jimnotgym 5mo agoThe only hams I ever enjoyed talking to were SOTA chasers when I was the activator. Bit of an all day job, and therefore something I don't really have time to do.
- souterrain 5mo agoPractically, this take emphasizes my point on repeaters. Each open active repeater develops its own subculture. (That said, the overwhelming majority of repeaters in the US are idle.) You may not be welcome on any given repeater.
- kotaKat 5mo ago"Ham radio is like Chatroulette in that you don't know which old man at the other end of the ionosphere you're going to end up talking with."
- thenthenthen 5mo agoThere are many cheap shanzhai android phones with walkie talkie ptt functions (around 400MHz iirc) for about a decade. We tried to convince manufactures to open up the software stack to no avail, while being bullied at local hackerspaces (“this is illegal!”). I am licensed.
- lxgr 5mo agoIt's mindblowing to me how modern cell phones have worse broadcast and P2P capabilities than what we had decades ago (when feature phones often featured FM receivers and could share photos via Bluetooth across manufacturers and OSes). Airdrop was the closest thing we had, and even that has been intentionally nerfed for non-contact senders. It's absurd that modern phones can talk to satellites hundreds of kilometers above, but not to other phones a few meters away in the same room, airplane cabin, train car etc.
- wolvoleo 5mo agoP2P capabilities aren't what the providers and governments want. The providers don't want it because they can't charge you for it. The governments don't like to see people communicate outside of their control. See how Apple caved to China making AirDrop no longer public and has followed suit in the rest of the world because other governments fear this capability too.
- euroderf 5mo agoSo, do phones in the "libre" genre have these features ?
- wolvoleo 5mo agoNo, but I think this is more because it takes them so much effort replicating the basic functionality and compatibility with e.g. android apps that they just don't have the energy for it. Also, the hardware for good peer to peer communication is just not present in regular phones. Some libre hardware projects do have optional addons for LoRa, such as the PinePhone: https://pine64.org/documentation/Phone_Accessories/LoRa/ https://pine64.org/documentation/Phone_Accessories/LoRa/
- wolvoleo 5mo agoNice!! I wish it could do DMR though. Analog isn't used to much anymore in these parts. Although to be more precise, HAM radio has declined a lot but DMR repeaters are linked in groups so it seems like there's a lot more activity.
- wolrah 5mo agoExactly my thought. APRS is nice but I'm just not interested in buying another otherwise analog-only radio. I know a lot of the popular digital modes are hard due to proprietary components but I'd be a lot more interested in something that supported digital voice and higher rate data modes even if it were just M17.