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$15 RTL-SDR for Radio Monitoring on your PC
The Backwoods Engineer Blog ^ | 3 April 2014 | The Backwoods Engineer

Posted on 04/03/2014 1:08:47 PM PDT by backwoods-engineer

This post is of interest to ham radio operators, and also anyone who wishes to monitor NOAA weather radio, police, fire, EMS, aircraft, marine, and other radio traffic using a $15 receiver plugged into your laptop.

The Chinese USB "dongles", originally intended to receive the Far East mobile television service, are being re-purposed as VHF/UHF receivers for many different modulation schemes and protocols.  The software to re-purpose them runs either on a PC (Win/Mac/Linux), or on a single-board computer like a Raspberry PI (Raspian Linux).

At about US$15, Ol' Backwoods just had to have one.

The RTL-SDR receives on 50 - 2200 MHz.    It is possible to receive HF; more on that in a bit.

Order your RTL SDR dongle from eBay or Amazon.
Then, use the instructions here to help you download the SDRsharp software; I used it on Windows 7.

The RTL-SDR can receive HF through the use of an upconverter you can buy on Amazon.

There is also a special direct-sampling RTL-SDR dongle available from Easy-Kits that receives 120kHz-54MHz, with an internal preamp to help sensitivity at HF.  It also works with the SDRsharp software described below.   At US$75, it's a bit pricey, but no more than the VHF/UHF RTL-SDR with an upconverter.  I understand the regular RTL-SDR can also do direct sampling to receive HF, but without an external preamp, the sensitivity is not good enough to receive shortwave signals.

Ol' Backwoods wants to use an HF-capable RTL-SDR to be able to capture PSK31 conversations from a dipole antenna at home, and push them through to my iPhone, even when I am not in front of the rig.

Antennas
The mag-mount antenna provided with the dongle is a joke for anything below about 800 MHz.

I cut the coax, saved the connector end, soldered on a dipole made of 20GA hookup wire, cut to the NOAA weather band, and hung it vertically from my upstairs ceiling.   The connector on the dongle is an MCX female, and adapters are available to other connector types; I just didn't have one on hand, and I wanted to get running quickly.

If you don't have an antenna, I might suggest this inexpensive scanner antenna for reception at home.  You don't even have to have it outside; I have a similar one in my attic.  Or, you can construct a dipole or ground-plane antenna out of hookup wire, like I did, but that won't be very wideband.

Running SDRsharp with the RTL-SDR

As the instructions for zadig and SDRsharp suggest, I first tried receiving wideband FM from a local FM radio station.  I was able to get that working within a minute of downloading the SDRsharp install.

The frequency adjustment is a little squirrelly; each digit has a "virtual" up and down button overlaid on it it.  Click near the top of each digit to increment each digit, and near the bottom to decrement.  There probably is a way to type in a frequency directly, but I couldn't find it.

The default RF gain is 0 dB.  That will work for nothing but super-strong FM broadcast stations.  Our local NOAA weather radio station, which booms in here 60 dB over S9 on my ham receiver, was not received AT ALL by the SDR, with my hanging dipole.

Receiving NOAA Weather Radio

In the US, tuning to NOAA weather radio is a good way to start getting the RTL-SDR to receive narrowband FM signals, as the stations transmit continuously, and they're easy to find.  It's always one of these frequencies: 162.400 162.425 162.450 162.475 162.500 162.525 162.550.

When I clicked the "Configure" button and increased the gain to about 20 dB, I saw the NOAA station at 162.450 MHz pop up in the center, and then when I clicked on the signal, it began demodulating.  I increased the RF gain to bring up the NOAA signal to 0 dBFS, as indicated on the spectrum display.  The filter bandwidth was set way too wide, and it was bringing in a lot of noise on the audio.  I had to cut the filter bandwidth to 8000 Hz (as shown in screenshot below), and increase the filter order to 400 to steepen the skirts of the filter, to get the audio sounding right.

My settings on SDRsharp for Windows are shown in the screenshot below, to receive our local NOAA weather radio station.  Notice the dongle's notion of frequency is wrong;  it displays a frequency 7 kHz too low.  There is a means to correct that, but I didn't fool with it.

Next, I want to get this working on a Raspberry PI, pipe in a decoder, and a GPS, and WiFi or Bluetooth, so I can get automated indication on my iPhone that there is a severe weather warning, no matter where I am on the road.


More You Can Do With Your RTL-SDR

There's a lot of software available for the RTL SDR, much of it as "plugins" to SDRsharp to let it do things it can't do natively.  I plan to try some of it, and report back here on the blog:

Have fun!


TOPICS: Computers/Internet; Hobbies; Science; Weather
KEYWORDS: hams; mustbuy; radio; scanners; sdr
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Full text as always for my FRiends, from this blogger with the FR seal of approval. I would appreciate a click, though, if you don't mind; there many more interesting articles at my blog of interest to FReepers; scroll down and look at the right margin.


1 posted on 04/03/2014 1:08:47 PM PDT by backwoods-engineer
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To: Kartographer

May be of interest to our prepper FRiends.


2 posted on 04/03/2014 1:09:33 PM PDT by backwoods-engineer (Blog: www.BackwoodsEngineer.com)
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To: backwoods-engineer

This is cool.

/johnny


3 posted on 04/03/2014 1:54:35 PM PDT by JRandomFreeper (Gone Galt)
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To: backwoods-engineer

Thanks !

bookmark bump


4 posted on 04/03/2014 1:59:58 PM PDT by JMJJR ( Newspeak is the official language of Oceania)
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To: backwoods-engineer

Looks interesting; bookmarked for later study.


5 posted on 04/03/2014 2:20:04 PM PDT by Charles Martel (Endeavor to persevere...)
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To: backwoods-engineer

These dongles are marginally useful but suffer severely from lack of input filters and gain distribution problems.

Probably fine for the intended application but in a dense RF environment intermodulation products make listening challenging, particularly if anything more than an inefficient antenna is used.

Even the better dongles, such as the Fun Cube Plus, with input bandpass filters are prone to overload, to the point where setting the LNA gain at maximum negative value (minimum gain) is necessary, and sometimes mixer gain and post mixer gain also have to reduced.

Been there, done that.


6 posted on 04/03/2014 2:23:49 PM PDT by JackOfVA
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To: All

Thread is back from the dead boys! Restored by Jim Rob himself! A trigger-happy moderator thought I was soliciting. Just want to tell everyone: I make not ONE DIME off any of the links in that post. Not even the Amazon links. I just want to bring everyone information useful to them. I love FR, and love the discussion here.


7 posted on 04/03/2014 2:34:32 PM PDT by backwoods-engineer (Blog: www.BackwoodsEngineer.com)
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To: JackOfVA
These dongles are marginally useful but suffer severely from lack of input filters and gain distribution problems.

Yes, of course they are not in the same class as software-defined radios from Flex Radio Systems or National Instruments (the USRP).

But what do ya want for $15? LOL

They serve many purposes, the least of which is introducing people to the world of signal processing on a PC with free software.

8 posted on 04/03/2014 2:36:32 PM PDT by backwoods-engineer (Blog: www.BackwoodsEngineer.com)
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To: backwoods-engineer

Wow! Great info there. Thanks for posting, I’ll go click up a bunch of links on your website.


9 posted on 04/03/2014 2:49:46 PM PDT by TigersEye (Stupid is a Progressive disease.)
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To: backwoods-engineer

Interesting little project.


10 posted on 04/03/2014 2:51:40 PM PDT by steve86 (Acerbic by nature not nurture)
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To: backwoods-engineer

Bookmark.


11 posted on 04/03/2014 2:55:33 PM PDT by SunTzuWu
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To: backwoods-engineer

Thanks for this info. I had not heard of this. Certainly cheap enough to try.

I just bought the radio shack emergency crank radio for $12.99- works great for Noaa weather.


12 posted on 04/03/2014 2:55:34 PM PDT by quimby
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To: appalachian_dweller; OldPossum; DuncanWaring; VirginiaMom; CodeToad; goosie; kalee; ...

Preppers’ PING!!

Hat tip to backwoods-engineer for the heads up.


13 posted on 04/03/2014 4:18:39 PM PDT by Kartographer ("We mutually pledge to each other our lives, our fortunes and our sacred honor.")
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To: backwoods-engineer
Cool dongle!


14 posted on 04/03/2014 4:42:52 PM PDT by JoeProBono (SOME IMAGES MAY BE DISTURBING VIEWER DISCRETION IS ADVISED;-{)
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To: mylife

May be of some interest to you.


15 posted on 04/03/2014 5:05:21 PM PDT by NYTexan
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To: NYTexan; LurkedLongEnough; AlexW; bikerman; Blue_Spark; bitterohiogunclinger; ...
Wow SIGINT for the masses!


16 posted on 04/03/2014 5:12:41 PM PDT by mylife (Ted Cruz understands the law, and is not afraid of the unlawful.)
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To: backwoods-engineer

If you have high speed internet ditch your cable TV bill.

http://www.youtube.com/watch?v=eOkK-zYiijo


17 posted on 04/03/2014 5:27:37 PM PDT by mylife (Ted Cruz understands the law, and is not afraid of the unlawful.)
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To: All

Language warning! I posted the wrong link.


18 posted on 04/03/2014 5:30:31 PM PDT by mylife (Ted Cruz understands the law, and is not afraid of the unlawful.)
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Correct link

http://www.youtube.com/watch?v=N6UZ73GsmxY


19 posted on 04/03/2014 5:31:32 PM PDT by mylife (Ted Cruz understands the law, and is not afraid of the unlawful.)
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To: backwoods-engineer
WOW, thanks, tech bump and bookmark.

Bookmark

20 posted on 04/03/2014 5:38:07 PM PDT by The Cajun (tea party!!!, Sarah Palin, Mark Levin, Ted Cruz, Mike Lee, Louie Gohmert......Nuff said.)
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To: Kartographer

THANKS!!!


21 posted on 04/03/2014 5:55:07 PM PDT by Vendome (Don't take life so seriously-you won't live through it anyway-Enjoy Yourself ala Louis Prima)
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To: backwoods-engineer

Bookmark.


22 posted on 04/03/2014 6:10:45 PM PDT by manic4organic (It was nice knowing you, America.)
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To: backwoods-engineer

Awesome! Bookmarking.


23 posted on 04/03/2014 6:11:55 PM PDT by TADSLOS (The Event Horizon has come and gone. Buckle up and hang on.)
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To: backwoods-engineer

Ping a ling a ding dong...my Icom 7100 just broke after 20 years of service. $15 is better than $1300.00 which is what I paid for that sucker 20 years ago.


24 posted on 04/03/2014 6:38:35 PM PDT by BreezyDog
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To: mylife
I used to listen to FM radio on an old HP spectrum analyzer. I'm all for wide open radios with plenty of options.

/johnny

25 posted on 04/03/2014 6:50:28 PM PDT by JRandomFreeper (Gone Galt)
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To: JRandomFreeper

Oh yeah I love wideband.
I used to build them.


26 posted on 04/03/2014 6:55:25 PM PDT by mylife (Ted Cruz understands the law, and is not afraid of the unlawful.)
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To: JRandomFreeper

Nice to look a 500 Mhz is a swack.


27 posted on 04/03/2014 6:56:28 PM PDT by mylife (Ted Cruz understands the law, and is not afraid of the unlawful.)
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in a swack


28 posted on 04/03/2014 7:02:00 PM PDT by mylife (Ted Cruz understands the law, and is not afraid of the unlawful.)
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To: backwoods-engineer
Full text as always for my FRiends, from this blogger with the FR seal of approval. I would appreciate a click, though, if you don't mind

I hope those on FR will give you that courtesy, and that they do the same for good-quality writing in general. It's a small payment for the value delivered - and thank you for an excellent and useful bit of writing.

29 posted on 04/03/2014 7:09:25 PM PDT by Pollster1 ("Shall not be infringed" is unambiguous.)
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To: mylife
My ICOM IC-T81A goes from 50 MHz to 1.2Ghz, but even with the mods to open it up, it is still limited on what types of modulation it will handle depending on what band it's on.

Sometimes it's just nice to listen to whatever, wherever.

/johnny

30 posted on 04/03/2014 7:09:55 PM PDT by JRandomFreeper (Gone Galt)
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To: mylife
My ICOM IC-T81A goes from 50 MHz to 1.2Ghz, but even with the mods to open it up, it is still limited on what types of modulation it will handle depending on what band it's on.

Sometimes it's just nice to listen to whatever, wherever.

/johnny

31 posted on 04/03/2014 7:10:03 PM PDT by JRandomFreeper (Gone Galt)
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To: backwoods-engineer

Bump


32 posted on 04/03/2014 7:16:57 PM PDT by Jet Jaguar
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To: JRandomFreeper
My ICOM IC-T81A goes from 50 MHz to 1.2Ghz,

My Kenwood TS-2000 goes from 1.8Mhz up to 1.2Ghz (not straight through of course..)

1.8-30Mhz is unlocked (recv/xmit straight thru.) I also get 50-54, 136-154, 220Mhz, 70cm and finally 1.2Ghz.

33 posted on 04/03/2014 7:33:02 PM PDT by usconservative (When The Ballot Box No Longer Counts, The Ammunition Box Does. (What's In Your Ammo Box?))
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To: backwoods-engineer
Thanks for posting this. I'm an Amateur Radio guy (General Class, studying for my Extra) and am interested in SDR also. Just ordered the Flex Radio 6700 (newest model) and am looking forward to playing with that.

Curious to know if the device you purchased would work on my 6-160 fan dipole?

34 posted on 04/03/2014 7:35:22 PM PDT by usconservative (When The Ballot Box No Longer Counts, The Ammunition Box Does. (What's In Your Ammo Box?))
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To: AlexW

ping


35 posted on 04/03/2014 7:46:13 PM PDT by knarf (I say things that are true .. I have no proof .. but they're true.)
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To: usconservative
Sure. You'll need an adapter from MCX to PL-259/SO-239.

If you're comparing it to the Flex Radio, though, the $15 dongle is going to come up a little short.

36 posted on 04/03/2014 8:22:34 PM PDT by backwoods-engineer (Blog: www.BackwoodsEngineer.com)
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To: Pollster1

Thanks much.


37 posted on 04/03/2014 8:23:41 PM PDT by backwoods-engineer (Blog: www.BackwoodsEngineer.com)
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To: mylife
Indeed. In fact, there is a blogger who has produced a book that hints at that.

Funny you should mention SIGINT; I spent years in SIGINT and ELINT. Given how our government's capabilities in this area have massively evolved, and they are turning their toys on the citizenry, I'm thinking we should fight back. I think it's ironic that a Chinese TV dongle should help us do that.

38 posted on 04/03/2014 8:26:02 PM PDT by backwoods-engineer (Blog: www.BackwoodsEngineer.com)
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To: BreezyDog

Well, you can’t transmit with it. And your ICOM is ten times the radio this thing is. But, for simple monitoring of public radio services, and your government, it’s just the thing.


39 posted on 04/03/2014 8:27:53 PM PDT by backwoods-engineer (Blog: www.BackwoodsEngineer.com)
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To: mylife

The dongle can only look at about a MHz (1.024 MHz with a 2.048 MHz sampling rate). It is nice to be able see a slice of spectrum, because you can click on various signals, and SDRsharp will start to demodulate the signal.


40 posted on 04/03/2014 8:30:58 PM PDT by backwoods-engineer (Blog: www.BackwoodsEngineer.com)
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To: backwoods-engineer

Fight back.


41 posted on 04/03/2014 8:32:44 PM PDT by mylife (Ted Cruz understands the law, and is not afraid of the unlawful.)
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To: backwoods-engineer
Been looking at the RTL2832U+R820T...for plotting ADS-B (aircraft) data.
42 posted on 04/03/2014 8:37:34 PM PDT by RckyRaCoCo (Shall Not Be Infringed)
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To: Nailbiter

bflr


43 posted on 04/03/2014 10:30:35 PM PDT by Nailbiter
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To: backwoods-engineer
I'm not looking to replace my FlexRadio with the $15 dongle. The FlexRadio is going to replace my aging HF station (a Kenwood 940SAT and a Kenwood TS-2000 that I'm very unhappy with.)

I'm more interested in the dongle as something to toy around with and potentially give to an elderly friend of mine to give him something to listen to. He's a stroke victim but can operate a computer and has a wire in the air. He's been unable to make much use of his police scanner since many of the local PD's have gone to digital trunking. I'll use two of these dongles for that.

Really appreciate you posting all the information you did --- if you have an Amateur Operators/Ham Radio ping list would you please add me to it?

44 posted on 04/04/2014 5:25:52 AM PDT by usconservative (When The Ballot Box No Longer Counts, The Ammunition Box Does. (What's In Your Ammo Box?))
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To: RckyRaCoCo

Yes, I believe there is an SDRsharp plugin for ADS-B. Look at the “instructions” link in the article above, and click on “Aviation” in “Applications”, I think.


45 posted on 04/04/2014 8:11:10 AM PDT by backwoods-engineer (Blog: www.BackwoodsEngineer.com)
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To: usconservative

You’re welcome. I actually don’t have a ping list. There should be a ham radio ping list somewhere on FR; I don’t know who does it, or how to find that out.


46 posted on 04/04/2014 8:12:27 AM PDT by backwoods-engineer (Blog: www.BackwoodsEngineer.com)
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To: backwoods-engineer
This post is of interest to ham radio operators, and also anyone who wishes to monitor NOAA weather radio, police, fire, EMS, aircraft, marine, and other radio traffic using a $15 receiver plugged into your laptop.

Just an observation:

The above is only half right. I've spent considerable time and effort into making sure my radio shack is capable on all possible bands and will work no matter what the grid status is.

This dongle may be good for entertainment purposes but the average ham will not see it as anything but a weak link if it requires a laptop computer.

Clicked through as requested.

47 posted on 04/04/2014 8:16:08 AM PDT by Bloody Sam Roberts (Truth sounds like hate...to those who hate truth.)
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To: backwoods-engineer; usconservative

I have a list, feel free to use it, it is on my profile page.


48 posted on 04/04/2014 8:27:44 AM PDT by mylife (Ted Cruz understands the law, and is not afraid of the unlawful.)
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To: Bloody Sam Roberts
This dongle may be good for entertainment purposes but the average ham will not see it as anything but a weak link if it requires a laptop computer.

You are probably correct. The "average ham" is probably not the target of this post, nor is he a reader of my blog, probably. This dongle requires some technical finesse to get working correctly for different kinds of modulations, something your average "appliance operator" will not take the trouble to do. Our hobby loses much because of it.

There are more and more-capable experimenters in the "Maker" and "DIY" communities than in ham radio, and that is sad. I have always been an experimenter, and I have had my ham ticket 33 years now.

That being said, this dongle is capable of serious SIGINT and monitoring of public radio activity, which is needed these days because of the thugs we have in government these days, who think nothing of violating out Constitutional rights.

No, it is not a $4000 ham radio that does everything but make you toast. At $15, it cannot possibly be anything close to that. But for those who are willing to learn, these little Chinese SDR dongles have much to teach. Too bad most American ham radio operators won't take the time to learn.

49 posted on 04/04/2014 2:48:13 PM PDT by backwoods-engineer (Blog: www.BackwoodsEngineer.com)
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To: Bloody Sam Roberts
This dongle may be good for entertainment purposes but the average ham will not see it as anything but a weak link if it requires a laptop computer.

Those of us who are into the digital modes like ol' engineer is will find alot of value in this little dongle. Combine it with the Ham It Up v1.2 - NooElec RF Upconverter also available on Amazon and you have a nice, cheap amateur radio band HF receiver also with the right software loaded on your laptop.

There are ALOT of hams that use desktops/laptops while on air. Some like me use programs like Ham Radio Deluxe to control my rigs either at home, or over the Internet (I do that from our cabin up north) and some of us also use third-party DSP filters and noise cancelling software with our older rigs to "clean up" the receive and pull out weak signals.

Computer use while on air is much more prevalent than you may think. I know some older hams (late 70's, early 80's) who use their computers on-air for many of the same things I do. These are the guys that were running packet radio on Commie 64's "back in the day" and they've kept up with computer technology.

One other tidbit: Many of the advancements in WiFi technology have their roots in ... amateur radio! There's a TON of wireless based network experimentation going on.

50 posted on 04/04/2014 4:25:22 PM PDT by usconservative (When The Ballot Box No Longer Counts, The Ammunition Box Does. (What's In Your Ammo Box?))
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