His Divine Shadow posted:

I asked this in the electronics thread, but I'll also post it here

Forseti posted:

I don't know about especially good AM reception, all I've ever used is the little integrated loop stick antennas that are inside my portable radios. I would guess that a very good outdoor AM antenna would be huge because the frequency is so low.

As far as what to do with an outdoor antenna, could you use something like an RTL-SDR + a Pi or other small computer to access over wifi/network? Basically you'd have the whole radio part outside, but you'd use it via software on your PC or phone. Not sure if that would work for you, I guess it depends on if you are after the radio programs themselves or you actually want to use radios to listen. You could rebroadcast from the SDR though I think, as long as a slight delay isn't an issue for whatever your use case is.

Minus Pants posted:

Thanks for the recommendations! How's the built-in tuner on the 7300? I'm seeing some mixed reviews. An external one isn't a big deal, I just want to order all at once.

Enos Shenk posted:

Hey radio dudes, I need you to tell me my idea is stupid and why.

So, I've had this crazy desire for a long time to build some kind of gadget that can "see" RF. Yes I know you can't see it, what I've always wanted to do was visualize what you would if you could actually see RF, and say for example gazed out towards an FM radio transmitter or something.

I've got a bunch of free time coming up soon, so I thought of actually giving it a go. I've got a lot of experience in various tinkering, and right now here's my current thoughts. Build a 2 axis motion controlled tripod head style device, mount a very directional antenna on it hooked up to an SDR. Hell I've got most of the required hardware just laying around. Have an arduino or other controller directing the head to step through arcs through the sky, measuring the signal strength of X frequency at each step and logging it. Through software and converting from arcs to cartesian coordinates and converting the signal values to an image approximate what the thing "sees".

I don't have a lot of experience with radio stuff, besides cobbling together an ADSB antenna for my roof. So I'm probably hilariously misunderstanding something here. If you rigged up such a system, does RF even behave the way I'm assuming? What my dumb rear end envisions in my head if you ran such a scheme would be something like a flare if you aimed it at a transmitter and only examined one frequency. Example:



Assuming you could process the input enough to discern a difference at each angle sampled, am I thinking completely wrongly, would there even be anything to see? Is it even possible to build an atennna directional enough to make this work? I'm thinking at the least an antenna that's restricted to a degree or two, and stepping through say 90 degrees of sky in both axes.

Motronic posted:

Switching power supply, USB3 device, etc. come to mind first as "things around my radio that I'd be looking at". Have you put ferrite cores on all the cables in/out around whatever that is that's producing the waterfall to see if you can lower your noise floor?

thehustler posted:

Do they go if you disconnect the whip?

Jonny 290 posted:

switching power supplies have notoriously unstable oscillators and you'll see shifts like that whenever something gets plugged into or disconnected from them, they heat up, they cool down, a stray neutron hits them, butterfly flaps its wings in Tibet...the list goes on. They suck real bad.

Tommah posted:

Those vertical lines could theoretically be generated by something plugged in your house, even if it's far from the radio itself. My uneducated understanding is that sometimes the rfi can travel across building wiring. Possibly it could be generated by something in your neighbor's (if you have one) apartment or even from a neighboring building through the outside power lines since the wiring is close/actually connected somewhere.

The best thing would be to turn off all power to the building and then turn breakers on one-by-one and check the waterfall each time. But it sounds like you probably don't have good access to that, so you could unplug everything in your apartment and then plug them back in one-by-one to see what generates which lines and also which lines are gone when everything's unplugged. If you have lines but nothing plugged in, then you can rule out stuff in your apartment causing it and your options to fix them start narrowing.

One thing that's killing my noise floor right now are christmas lights -- ones on my house as well as neighbors'.

It helps to have an external battery when testing this stuff so you can completely eliminate interference to the transceiver coming through the power lines.

Buy yourself a big bag of ferrites/chokes because once you start hunting RFI and noticing improvements, you'll never stop seeking the interference.

Motronic posted:

Voltage changes from the utility, voltage sags in your house (i.e., fridge, oven, other high current devices turning on), the equipment on the load side of the switching supply changing loads, pretty much anything like that. I would expect it to be close to your receiver if it's coming through that way.

If you really want to narrow things down run everything radio-related on battery and start turning thing on and off in your house. Or just start will being on battery and killing the main breaker. Then see what you have. Then start putting on ferrite chokes/rearranging cables to get your rig as quiet as possible. Then start turning things back on and see what's spewing what.

yoloer420 posted:

I managed to get this with my baofeng held up to my mobile phone doing the decoding. I'm absolutely shocked it worked so well.

Helianthus Annuus posted:

ickna posted:

kind of a weird long shot, but the waterfall image looks like it is mirrored, like they transmitted it on LSB.. and the decoder is expecting the upper side band? I'm not sure how you would go about inverting the recording though.

quote:

The 2nd type of file to be sent with EasyPal is called Hybrid. This way of sending a file is much quicker but you are not receiving the image via the radio, you are only receiving a short header that tells EasyPal where to go and download the file and display it on your screen, This all goes on within the program. The sending station uploads "FTP" a file to a server then transmits its location and your program grabs it via the internet and displays it. This is nice when the bands are real busy as you have more chance of getting the short header than getting a 3 minute transmission. When receiving a Hybrid image there is no progress bar.

Jonny 290 posted:

anyways i'm not sure what that mode is but have a suspicion it's ALE http://hflink.com/automaticlinkestablishment/

thehustler posted:

It looks like only 14 different tones, which is odd. You’d expect 16. Or some other power of 2

Jonny 290 posted:

Not really, no. CW decoders are actually really finicky to write - not because it's hard to decode CW, but because it's hard to machine-decode human-sent CW.

Even FLdigi's pretty lovely decoder works perfectly with computer-sent CW, but it completely falls over with a real fist on the other end (IMO).

xblackdog posted:

I can't remember because I don't do that kinda stuff, but isn't there a way to be given bits of out of band spectrum to try out new protocols?

wolrah posted:

IIRC channel 6 (27.025) is the unofficial DX channel, referred to as the Super Bowl.

Sir Mix-a-Lot is apparently in to CB DX and goes by the handle Prime Minista.

https://www.youtube.com/watch?v=1IfS4oMa1Jg

Big Mackson posted:

Discovered these signals that lasted a short while so i recorded this.

What does it mean?

horse_ebookmarklet posted:

Maybe 1.5 years ago in this thread I had an idea for an ic7300 mod I could maybe sell.

Turns out having just an idea is worthless.
Doing a proof of concept is a lot of fun and rewarding.
Making it into a thing you can let other people use is extremely difficult, time consuming, and discouraging.

I made a halfway ok youtube video, and wrote like 7000 words of documentation
https://www.youtube.com/watch?v=1HstbYwh1uc

What do people think? Looking for some gentle reality check here.

I've spent so much time on this I think I've lost sight if people will actually want this thing or what people's expectations are.
I think I see the light at the end of the tunnel for this project. Hopefully it is not the light of an oncoming train.

Big Mackson posted:

Finally done with drivers. only small adjustments to them and sealing holes is left.




edit: snipe
edit: its super easy to get in contact with ISS.

Big Mackson posted:

The Muffinlord posted:

Anyone have experience using one of those ninety-dollar mag loops off Amazon? I got a new Xiegu X6100 to play with and it hates my old 817's Miracle Whip, at least as far as reception's concerned. I'm not quite ready to put together the whole-rear end PowerPoint I would need to sell the wife on letting me plunk $600 on a name-brand loop, and believe me when I say it's safer I do not try to manufacture one myself. No trees suitable for a wire and nowhere to mount a vertical that's not going to look comically out of place in our neighborhood, either.

EDIT: the antenna in question