Checked in to my first net. My J-pole works great! :D
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Finally caught that signal at 146.436 MHz that I've been curious about for a long time. Pretty sure it's DMR. :3
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dsd doesn't support reading WAV files, DSD+ is a Windows application, and dsd-fme seems to not support reading files at all despite claiming being able to.% file untitled.wav
untitled.wav: RIFF (little-endian) data, WAVE audio, Microsoft PCM, 16 bit, mono 48000 Hz
% dsd-fme -i untitled.wav
██████╗ ██████╗██████╗ ███████╗███╗ ███╗███████╗
██╔══██╗██╔════╝██╔══██╗ ██╔════╝████╗ ████║██╔════╝
██║ ██║╚█████╗ ██║ ██║ █████╗ ██╔████╔██║█████╗
██║ ██║ ╚═══██╗██║ ██║ ██╔══╝ ██║╚██╔╝██║██╔══╝
██████╔╝██████╔╝██████╔╝ ██║ ██║ ╚═╝ ██║███████╗
╚═════╝ ╚═════╝ ╚═════╝ ╚═╝ ╚═╝ ╚═╝╚══════╝
Build Version: AW 2025-162-g86b8900
MBElib Version: 1.3.0
CODEC2 Support Enabled
Audio In Device: untitled.wav
Err: 6; Connection refused;Input/Output options:
-i <device> Audio input device (default is pulse)
/dev/dsp for OSS audio (Depreciated: Will require padsp wrapper in Linux)
pulse for pulse audio signal input
pulse:6 or pulse:virtual_sink2.monitor for pulse audio signal input on virtual_sink2 (see -O)
rtl for rtl dongle (Default Values -- see below)
rtl:dev:freq:gain:ppm:bw:sq:vol for rtl dongle (see below)
tcp for tcp client SDR++/GNURadio Companion/Other (Port 7355)
tcp:192.168.7.5:7355 for custom address and port
m17udp for M17 UDP/IP socket bind input (default host 127.0.0.1; default port 17000)
m17udp:192.168.7.8:17001 for M17 UDP/IP bind input (Binding Address and Port
filename.bin for OP25/FME capture bin files
filename.wav for 48K/1 wav files (SDR++, GQRX)
filename.wav -s 96000 for 96K/1 wav files (DSDPlus)
(Use single quotes '/directory/audio file.wav' when directories/spaces are present)
% sox untitled.wav -t raw - | dsd -i- -w decoded.wav
Digital Speech Decoder 1.7.0-dev (build:-128-NOTFOUND)
mbelib version 1.3.0
Writing audio to file decoded.wav
Audio In Device: -
Total audio errors: 0
Total header errors: 0
Total irrecoverable header errors: 0
+P25 BER estimate: 0.00%
-P25 BER estimate: 0.00%
Exiting.
% ls -lh decoded.wav
-rw-r--r-- 1 <> users 44 Jul 9 08:43 decoded.wav
% cat decoded.wav
RIFF$WAVEfmt @>data% Eric K3FNB (they/them) likes this.
I'm unsure. I think you can pipe it into dsd. I had more luck with dsdcc.
You may need to convert the wav to the correct bitrate. I'm not sure
Finally got something that's voice, though it's unintelligible.
sox untitled.wav -t raw - | dsdccx -i- -o- | ffmpeg -f s16le -ar 8k -ac 1 -i pipe: decoded.wavAccording to here, those are the correct input and output formats:
- Input as S16LE samples at a fixed rate of 48kS/s
- Audio output as S16LE samples at 8kS/s rate directly out of mbelib or upsampled to 48kS/s
it could be encrypted. Does it sound like someone rustling around in their backpack?
This is a sample I captured of AES256 encrypted DMR voice
https://next.ericcodes.io/s/Eir5iLTtnikoGFK
Needed a tube bender for my next project, but my local hardware store was out of ones that could handle ½" tubing, so I had to order from McMaster–Carr.
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Oh!
Then that's why your question is important. I'll be following the answers to learn from this audio clip 🙂
Take care 👋
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That wasn't my goal, but that might be doable, especially if you set up the legs to be telescoping. (I was just trying to get a low SWR in 2m.)
If you want guidance, I'd direct that request at @DD8SF . They've been guiding me through my entire antenna building journey. :3
Now I need to build something for 2m. :3 #AmateurRadio #HamRadio
Finally got my copper pipe dipole working well on 6m! :DProtip: Make sure your test loads are suitable for RF. :(
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Finally got my copper pipe dipole working well on 6m! :D
Protip: Make sure your test loads are suitable for RF. :(
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LMR-240 is pretty easy to wind around a toroid and has a pretty low loss. :3
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May have limited bandwidth.
Personally, for a multiband antenna, I much prefer a tuned doublet - those old timers, with their open wire feed lines, knew what they were doing.
My multiband antenna is a doublet cut for 160 meters made with aluminum fence wire and fed with twin lead. Cheap and light and loads 160 through 6 meters with minimal loss using balanced line.
Lee K9CM
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What's kind of cool about my transceiver is that, even when you are using the built-in USB audio interface to work with a computer, received transmissions' audio will still be played over the internal speaker by default. I found that out while running WSJT-X, and heard what FT8 sounds like. :3
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Made a lot of progress, but it looks like the SWR minimum is starting to creep up as I continue to shorten my dipole (which brings its ends away from the stucco walls).
(I did make sure to recalibrate after changing the frequency range, by the way.)
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It's workable, hard to predict what will happen given that there's structure interaction. VSWR might even go down as frequency goes up.
Does the antenna material permit bending back on itself rather than cutting? (Cutting is fine, but trying various bends gives you more flexibility to make sense of what's happening and to experiment.)
Kind of wild that I heard about this on a regional repeater yesterday long before it surfaced on the Web. :P
2025 Coeur d'Alene shooting
On June 29, 2025, at approximately 2 p.m. PDT, multiple firefighters from three companies were shot in Coeur d'Alene, Idaho in the city's Canfield Mountain Natural Area after a 20 acres (8.1 ha) fire was intentionally set in a plan to ambush them. Two firefighters on Canfield Mountain were killed and one injured. Both firefighters were pronounced dead on scene. Kootenai County officials have not yet publicly provided identification details of the two firefighters. The Kootenai County Sheriff's Office confirmed on their Facebook page that members of the SWAT team located a deceased male with a firearm found nearby at around 7:40 p.m. The shelter-in-place was lifted but the wildfire remains active. Sheriff Norris said it is unclear whether the man shot himself, but authorities believe he was the only shooter. The sheriff told reporters that the attacker had also started the forest fire. Modern high-power sporting rifles were reportedly used in the shooting.
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Spent some time working on matching transformer baluns with @DD8SF today and after winding all kinds of them only to run into far too much inductance for 6 meters, they suggested a parallel coax balun like Figure 24.72 from the Antenna Book, with four turns of the parallel lines around an FT240-43 core. (RG-174 was the only coax I had that was thinner than the "400MAX" I usually use.)
Unfortunately, as it stands, the pictured setup still has an SWR that's too high. :(
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Have folks heard about this?
Mysterious Antennas Are Appearing in Utah’s Hills and Officials Are Stumped
Strange antennas have appeared in the foothills around Salt Lake City and authorities have no idea what they are or who put them up.As first reported by KSLTV 5 in Utah, people first began noticing the antennas a year ago. They’re simple machines made up of a LoRa fiberglass antenna, a locked battery pack, and a solar panel to power it. The Salt Lake City public lands department has been pulling them down as they find them, and told KSLTV that there have been as many as a dozen.
It’s illegal to place structures on public lands without permission and some of the antennas have appeared on steep peaks. In one instance, the removal of an antenna required a team of five people. Other antennas were found on land managed by the University of Utah and the Forest Service.
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@vvbudh
I had the same question. Now I'm going down a rabbit hole of: How would one actually measure / infer radiation resistance?
@vvbudh I'll admit I didn't go far down that hole. Not surprising but I couldn't find any practical way to measure it.* The best one can do is a calculation/simulation and work off those assumptions.
In the end, the real world is too far from the ideal used in calculations. Just try for as long and high a radiator as reasonable.
*Perhaps one could measure the radiation of very small antennas and work backward but not practical below ?UHF?, or maybe higher?
@vvbudh a single signal strength report at distance doesn't account for radiation pattern or path losses. It's nice to know that you're getting the signal to that location but really doesn't tell you anything about how much energy the antenna radiated versus how much it dissipated as heat or other losses.
A dummy load can have perfect SWR and zero radiation losses. Measuring out how much energy is actually radiated from an antenna in all directions is difficult.
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Weird, it sounds kind of unstable.
If you have a SDR dongle, getting an I/Q recording of that might be more useful.
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Crimped my first coaxial connectors today.
It took a few tries before I made a successful cable, but that's just how I learn. :P
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Would be interesting if I could figure out a way to use a network of filters to select a balun to use for each frequency range. :3c
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Seems like there's a frequent #OSCAR transmission on 144.388 MHz here in Seattle. Not sure what it is specifically. :3c
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My copper pipe dipole apparently has a ~13.5Ω characteristic impedance because of the surrounding structure. :P
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What did you expect to see in the Smith diagram?
Hint: Look at one band at a time. Too much span of frequency is just confusing in a Smith.
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After my QRZ-1 showed up today, I replaced the stock rubber ducky antenna with a whip. 👍
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One nice thing about #AmateurRadio is that it's noncommercial by law, so if some tech bro asks about how it can be monetized, you can reply with "that's illegal". :3
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"Oh, we'll just change the allocations then."
This post from @kb6nu is a couple years old now, but it's still an on-going conversation: https://www.kb6nu.com/stock-traders-petitioning-for-high-power-access-to-shortwave-frequencies/
If I'm reading this correctly, I need a little less inductance and a little more resistance at 52 MHz to match the 50Ω reference impedance, but the latter seems a bit odd. I have this as the topology of my test rig, but maybe 25Ω is needed between "center" and ground? Not sure. :/
Hello HF bands! 👋
Just got a perfect score on my General exam, after the VEs had to watch me fumble and fail to get Zoom to work properly on my Linux desktop. (I got everything but my microphone to work.) They let me have a physical calculator because of the mess…only for none of the questions to involve math. :P
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Anyone know the history of why there are so many call sign prefixes in the US? Did each of them originally mean something different?
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I'm not sure what you mean by so many. Call signs used to be a fairly good indication of where the station was. I had N2 when I was in New York, KH6 in Hawaii and KE1 in Massachusetts. As with commercial stations, calls start with N on the east side of the country and W on the west.
I'm not that active anymore. I think people tend to keep their call sign when moving or go for a vanity call so I'm not sure prefix is still a good indication of region.
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https://www.eham.net/article/38849
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Anyone know how long it takes qrz.com to sync their database with the FCC's?
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≠
in reply to Neil E. Hodges • • •≠ is ignored
The class war is always the poor versus smarter people
Gas the poor
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