Ham Radio - Viewer request. - Web based SDR radios you can listen to for free.

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Oh youtubers and fellow hams

well a couple of weeks ago when I did my

little test with my magnetic loop where

I wanted to see if it would change and I

moved it down near the ground I had a

viewer say hey could you do a video on

web SDRs you see I used the web SDR as a

test in that video monitoring my signal

a few hundred miles away and he he wants

to know you know what they are what

they're used for sure that sounds like a

good idea I was going to do a video

today on that chameleons CH a loop to

the magnetic portable loop portable

magnetic loop but boy there's a big

low-pressure center coming across the

country and we've got 30 to 40 mile an

hour gusty winds today coming out of the

West so I'm not doing anything outside

so web SDRs internet accessible

software-defined radios that you can

listen to in your web browser all over

the world really cool let's go to the

computer and have a look at what sdrs

are and what the web SD ours are let's

take a look at a very simplified diagram

of a modern receiver I left one

component out down here I didn't think

about it down here would be a local

oscillator that would feed the mixer

so anyway your signals come in through

the antenna and then you've got a pre

selector on filter now the pre selector

is a bandpass filter that would be used

to sort of narrow down the amount of the

amount of RF energy coming in to the

frequency that we are or the area of the

frequency that we're interested in then

you'd have that local oscillator which

your vfo tunes and it feeds this mixer

and what comes out of the mixer is the

sum and product of the signals and the

vfo is set to a frequency that when

mixed with the incoming RF will produce

a sum or product on an if' frequency

that matches what we're interested in

listening to out here and then that if'

chain will filter and amplify the signal

and then you've got a detector and

demodulator that D modulates the audio

and finally drives a speaker so that's a

very simplified diagram of a modern

receiver in an SDR radio the hardware is

greatly simplified you're down to a

basic front-end and then some analog to

digital conversion where the RF itself

is actually sampled and then finally

detection and demodulation is all done

through software making the radio

completely flexible it can receive and

process just about any type of signal

that the software can handle what about

SDR hardware well here's some examples

of some common SDR hardware these

low-cost USB dongles are available all

over Amazon and other places for very

low cost I've seen them as low as 20 or

even 15 dollars may be cheaper nowadays

often they're kind of limited in that

they can only go from 70 megahertz up

through microwave frequencies but some

are manufactured with lower HF range

capabilities already built in and there

are articles out there on how to hack

some of these for direct RF sampling to

get them down to HF commercial hardware

like the SDR play pictured here our

manufactured purpose-built to operate on

the entire spectrum from very low

frequencies maybe 100 kilohertz all the

way up through microwave but they

usually cost a bit more so there's

plenty of hardware options available

software there's a lot of free software

out there there's some commercial

software but there is also free software

a popular one for Windows is HD SD are

shown here and it allows you to tune all

over the radio spectrum look at a

waterfall of the spectrum here and see

where the signals are pick and choose

the signals you want pick and choose the

mode that you want

am/fm lower sideband upper sideband CW

DRM even you know since since you're

defining your radio and software you can

set up all kinds of demodulators on the

linux side of things you've got programs

like GQ rx shown here which was built

using GNU radio sort of a Lego building

set for software-defined radios

there's also cubic SDR which is starting

to gain some popularity I really like

the interface on Kubica SDR it's my

favorite right now now what people did

was they figured out that since that

signaling is digital you should be able

to stream it across the internet and

they started coming up with web-based

SDRs and right here we're looking at the

page for web SDR org there are two or

three others I think there's one called

SDR HU and there's a third one that I

can't think of right off the bat but I'm

just going to use web SDR org for my

example I'll put links to the other ones

and this one in the description below

this will display a list of web SDR

radios that people have set up now these

are all voluntary if we go down here to

the map

you can see that all over the world

there are receivers set up look in

Europe they're really clustered in

Europe there's just tons of them these

are basically radios that you can tune

into and listen to all over the world is

that is just too cool isn't it

I use them for testing when I was up

here in Indiana I would connect to some

of these and see where my signal was

getting how far out I was getting and

what it sounded like

there handy for that I used it in that

antenna test video so they're handy for

testing your your antennas your radios

out seeing what your signals like you

know or if you're just trying to do some

shortwave listening and and you want to

listen to a radio in South America you

know you can come down here there's

several of them in South America or you

know if you want to listen to one and

hey look there's one in South Africa

there's one in Australia you know what

if you want to listen to what's going on

in the shortwave bands or the a.m.

broadcast band or the FM broadcast band

in Australia you can probably do that

now these are not all the same as I said

they're they're set up by volunteers so

some people set them up for specific

things for example here in the list

right here number 188 we can see there's

some information here about what it is

and where it is I think this one's in

Italy and he's only got it set up to

cover two metres and 440 or right here's

another one that has only set up to

cover 160 meters and 80 meters so

sometimes they're kind of limited in the

bands that they cover oops didn't want

to do that yet other times they're more


this one here

covers the entire HF spectrum from 0

kilohertz to 29.1 60 megahertz that's

that's quite a broad range there's a few

like that some of the others will have

bands set up like this one is covering

17 meters 20 meters 40 meters 60 meters

80 meters and 160 meters and he's on a

240 5rv antenna they'll put some

information over here as to what they're

doing so yeah it's a it's a pretty

interesting thing so let's pick let's

pick one that's here in the US go back

to the map here and let's see here

number 78 let's go see what he is

alright so we'll scroll up here number

78 he's covering some odd bands well it

looks like he gets 20 meters there he

gets 40 meters there okay let's go to

that one it's in Georgetown Kentucky all

right when you go to the SDR you'll get

the web interface now this software that

they're using runs on a Linux server and

it is publicly available I believe I'm

not sure about the setup I might do a

video on setting on up I might actually

do that just took this for a video

it shouldn't be too difficult to do okay

so we don't want to be on 7,200 I know

that right away let's just move here and

I'll zoom in a little bit and you can

see the interface is pretty nice on this

one here is our tuning I have a fairly

poor internet connection that's why this

graphic garbage is happening

usually the waterfall stays pretty clean

you can see the signals you can easily

and quickly and tune around by simply

sliding this you can punch your

frequency in here you can move it in

steps you can adjust your filter if I

use the mouse button mouse scroll wheel

to scroll in I can actually drag the

side of the filter

I want to widen or narrow it I can

change modes over here am/fm other side

then lower sideband

upper sideband narrow I can adjust the

filter wider or narrower CW so it's you

know it's a pretty nice radio receiver

and right now I'm listening to signal

Silas machine in Kentucky


pretty neat so that's basically how web

SDRs work and how you can use them to

tune around on radios all over the you

all over the world pretty cool

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