Justin K5EM

Tech, ham radio, hacking, weather. I enjoy experimenting with SDR, designing and testing antennas, contesting (usually with the team at KZ1W), SOTA/POTA, and satcom. Professionally I'm a hardware/FW/SW engineer and have spent most of my career in the drone industry. I enjoy making maps, both with drones and otherwise, with a focus on multispectral data collection and analysis.

Created satmatch.com to help satellite rovers better plan operations.

DXPedition @T88WA

He/him

2025-06-07

@ExplodingLemur @m1geo if you order a replacement, any chance you can order a spare and let me buy it off you? I've been trying to purchase for a while but never got a response. Happy to send you a paid label.

2025-06-07

@ExplodingLemur @m1geo if you order a replacement, any chance you can order a spare and let me buy it off you? I've been trying to purchase for a while but never got a response. Happy to send you a paid label or just buy you a ☕.

2025-06-03

@hine yeah I think so let me double check with Nick first

2025-06-02

@azonenberg my kids are avid readers so a lot of more complex words they read before they heard, which has resulted in a lot of interesting pronunciation that is hard to break the habit on. Tonight it was electrolysis, pronounced "electro-lysis" rhyming with electro rices. Hopefully he'll get that one sorted out before his presentation on it 😂

Justin K5EM boosted:
2025-05-24

Announcing: justaqrcode.com.

Tired of "free" QR code generators that are full of ads and trackers, that share your data, and that want to sell you something? Me too. Here's my act of resistance: I made a one-page site that works entirely in your browser to generate a simple QR code. And that's all it does. You can download the HTML page and run it locally, even. Read the source; nothing up my sleeves. Just a QR code.

My offer to you -- I will continue to pay for the domain name and web hosting for it, myself. If you find it valuable, you can pay it back by creating your own useful thing for the world and releasing it for free. Let's take back the friendly web, one vexingly-monetized utility at a time!

#QRcode #Free #FriendlyWeb #Resistance

Justin K5EM boosted:
2025-05-16

I personally believe that most effective way to speed up CW receiving is by practicing ICR (Instant Character Recognition). This method has had the largest effect on my receiving. Even short practices seem to have noticeable effect.

I previously released iOS App for this and now it is available as web based. Remember to use physical keyboard!

Go a head and try it! Post your results too!

cuf.fi/morose/

#morose #cw #morse #icr

Screen shot of CW practice web app.
2025-05-14

@tsherrygeo you know the maths. You'll be ready.

Justin K5EM boosted:
Hong's Electronicshongseleco@fosstodon.org
2025-05-04

I’ve been named the 2025 “Top Graduate Student” for the MS in Electrical Engineering program at Wright State University.

Truly honored and grateful to be recognized for the countless late nights spent on coursework and research—especially the collaborative work with The Ohio State University.

Huge thanks to the incredible faculty, friends, family, co-workers, and mentors who supported me throughout this journey.

Justin K5EM boosted:
2025-04-11

So the reason my IC-7300 was so deaf this week is that it was mistakenly plugged into my X30 VHF antenna. My LDG Z-100Plus tuner was working overtime and I just couldn't hear anyone. I did manage to get a QSO on 30 meters CW with it 😬

@k5em made this wonderful meme of the situation.
#HamRadio

The "This is fine" dog sits at a table in a burning room. An IC-7300 is on the table and the dog is labeled "LDG".
2025-03-19

@fl_0 shoot me an email (on qrz) and I'll send you some code. The Y axis direction is flipped which makes the Polar to Cartesian math a little weird.

2025-03-19

@fl_0 no, but they're just manually formatted SVGs. Open one in a text editor and you'll get the idea. I use drawSVG in python now, initially I wrote them by hand.

2025-01-05

@grajohnt only if it's linearly polarized. If it's circular you'll lose 3dB.

2024-12-19

@vk6flab sure, but the price for the package deal is a bit higher, and the lead time is pretty long

2024-12-19

Today is your last day to order a SotaCAT this year! Get WiFi control, click-to-tune spotting, and SotaMAT integration on your KX2/KX3. We have a few in stock still; any in-stock orders today will ship tomorrow, then we're taking the holidays off. #hamradio
store.invertedlabs.com

A close up of an Elecraft KX3 radio sitting on a park picnic table, with a blue SotaCAT dongle plugged in on the lefthand side.
2024-11-17

@Dtl wait is there another way?

2024-11-14

@SymTrkl check out the rest of the thread. Not likely to be anything in orbit, unless satellites start work on the hour, but I can understand why this is one hypothesis.

2024-11-14

@azonenberg check out the rest of the thread, but no, they're industrial 27MHz(ish) PVC welders! If I zoom way into them there are features that wouldn't likely be present with a doppler reflection, a quick modulation on top of the blip/chirp/fishhook, whatever we want to call it. In Palau they covered the bands, making 10m difficult to use at times.

2024-11-14

Thanks to the operators of the VK2GGC SDR for the ability to create some of the images above by listening in on the other side of the world. The rest were heard and screenshotted on my RX-888 MKII SDR here in Seattle on a rainy afternoon. Antenna was a 40m EFHW about 20ft off the ground, and these were likely coming in from Asia or Central/South America based on the band conditions at the time.

Spectrogram showing more blips and bloops.Spectrogram showing more blips and bloops, this time focused on the 10m amateur radio band and just below.
2024-11-14

Want to hear these for yourself? Pick a websdr or kiwisdr somewhere around 3000km from where plastic products are manufactured, and have a listen between 26 and 28MHz. If the sun is up and the production lines are running, you might catch something!
vk2ggc2.ddns.net:8074/

2024-11-14

So, back to hearing them in Palau. We can only guess that we were hearing the startup of manufacturing lines one ionospheric hop away in Indonesia or Vietnam. These are just guesses, as these signals reflect and refract off the ionosphere and could be coming from significant distances at times.

This image is a polar azimuthal map focusing on Southeast Asia and surrounding regions. It shows geographic areas like China, Japan, the Philippines, Indonesia, Thailand, Vietnam, and Australia, which are labeled and outlined in black. The map uses a blue color to represent the surrounding bodies of water, such as the South China Sea and the Pacific Ocean. Latitude and longitude lines are displayed around the curved edges of the map, with degree markers running from 240° to 310°. The map provides a detailed view of countries and major islands in this part of the world, centered on Southeast Asia.

Client Info

Server: https://mastodon.social
Version: 2025.04
Repository: https://github.com/cyevgeniy/lmst