Basic blue dongle (820T2 chip)
Basic black dongle
Dongle with Up Converter no switch $53
Dongle with Up Converter w/switch $70
NooElec Up Converter (Ebay)
NooElec Website (Ham it Up, 9:1 Balun, Isolation Boxes)
Mr. Carl Laufer’s website: http://www.rtl-sdr.com/.
His Book:The Hobbyist’s Guide to the RTL-SDR: Really Cheap Software Defined Radio
How important are survival communications? From a prepping budget perspective, I’ve asked that question a lot. And unfortunately, as with many subjects I’ve covered, there is a ton of misinformation out there about the subject. When you buy a “survival radio,” like the ones with the little solar panel and hand crank, you are buying a multi-band receiver, and you’ll pay more depending on how many bands you want. A basic radio, some even under $20, will be AM/FM, and most of them also have the NOAA weather channel, which is 162.4 mhz and a few other places. Pay a little more and you may get some of the Ham radio bands, but you will seldom hear any traffic on those bands, because the included whip antenna is not made for those frequencies. Police, fire, airplane, and a hots of other frequencies that would be nice to monitor in a survival situation are not in those radios. Getting all of those frequencies, until now, has been very expensive. This article is about a newer type of radio called “Software Defined Radio,” or RTL-SDR, and it changes everything.
As I’ve explained in my previous two articles on radios, when you see a Baofeng or Wouxon “Ham” radio for under $50, that isn’t going to help you much in a survival situation. Don’t get me wrong. They are great radios, and person to person, I don’t think you can beat them for usefulness, but if you want to find out what is going on in the world around you, those radios are useless. The Baofeng UV-5R, (currently just over $30 on Ebay) is probably the most recommended on most of the survival boards. It covers 136 mhz to 174 mhz, known as the “2 meter” Ham band as well as 400-520 mhz, which is the block that covers most commercial handhelds. Those frequencies are called VHF, or “Very High Frequency,” and they are limited in distance to “line of sight.”
On the ground, person to person, the curvature of the earth prevents those radios from reaching out to each other further than about 7 miles for a 6 foot person holding the radio to his mouth. In practical experience, they never go more than a mile or so, because of the stuff in between the radios. Police, fire, and even cab companies use a system of “repeaters” to stretch the usable distance of VHF radios, and the Baofeng is made to use those repeaters. It will broadcast on one frequency and listen on another. Officially you need a license to do this, but the radios are shipped with the channels open. Ham radio clubs almost all maintain a local repeater for you to use once you are licensed, and it will reach out to about 40 miles from the base station when the base station has power.
The problem is, if you look at the base of the large antenna towers in your area, you will see a propane tank on most of them. Some repeaters are solar powered, so post-collapse, there is a decent chance that they will work, but the ones with the propane generator probably aren’t going to function after a couple months. The Ham club repeaters are mostly just on grid power. That is why the Baofeng radios are so cheap.
Radio waves under 30 megahertz (30,000,000 hertz), also travel in line of sight, but they have a funny property that was discovered decades ago that makes them capable of traveling all around the earth. At certain times of day (usually at night actually), those waves, called “High Frequency” or HF, will bounce of the ionosphere and keep bouncing. Real Ham radios that cover those HF long distance bands are in general crazy expensive, from the high hundreds to mid thousands. And the rub is that when you buy them, they only cover the amateur radio Ham bands.
This is going to be the first of what I hope will be several articles on a fairly new technology called “Software Defined Radio,” and it really changes the game when it comes to worldwide communications on the cheap. I’m just digging in myself, so I’ll cover the stuff I have learned so far, so we can go learn it together. The radio itself can be had for less than ten bucks, but it only receives. I do plan to get into the transmit radios down the road and I have ordered a couple, but there are much more serious cost vs. benefit considerations when it comes to buying what the Hams call a “QRP” radio, which is a low wattage radio meant to reach out to the other side of the planet.
The Basic RTL-SDR Radio
The physical components in a traditional radio are not the only things that make it expensive. The circuit has to do a lot of things, and the research that goes into those things is substantial. Receiving a signal starts with the antenna, which receives the wave of the signal, and passes it to a crystal or chip that de-oscillates it into a tiny little sound. That tiny little sound then has to be amplified, usually by a transistor network, and the slightly bigger signal is then processed into filters and other amplifiers, for what eventually comes out of your speaker. Add some control circuits, displays, digital display driver boards, and the firmware to make them work, and it adds up to a pretty big engineering project. Simple, single channel radios, especially QRP radios (usually around 7 mhz), can be had for cheap, but until now any kind of multi-band receiver has been expensive.
Then someone in China decided that the consumer market needed a USB dongle that could receive TV stations, and they knew it had to be cheap. The resulting product is ten to twenty bucks and it is still being sold worldwide as a TV receiver only. Enter the geek brigade, who quickly figured out that this new chip could be used to receive a very wide band of frequencies, and because it was already digitizing and tuning the signal, a simple software program could control your listening enjoyment.
I am not going to get into the whole story or explain the chip structure because from a survival perspective, GO AND DO IT is all that matters. Their are now hundreds of websites that have information on the SDR radios, and the best book is available on Amazon for $18, free on Kindleunlimited The kindle version is updated all the time with new information, but even the printed version is very up to date. I am writing this at the end of August 2015, and the print date of my book is August 12th 2015. They are using just in time printing, so don’t hesitate to order the book.
The website from the author, Mr. Carl Laufer, is http://www.rtl-sdr.com/. I wouldn’t say it is the only definitive guide, but it will get you started, and it links to all of the resources you need. They also sell a slightly more expensive dongle that includes some signal filter upgrades and a more temperature stable tuning chip. The cheap dongles drift a bit, which can be a pain if you are using a frequency storing program to check different channels.
When you get your dongle, DO NOT install the software that comes with it. You can also throw away the remote control, unless you want to use it to watch TV. Download the Zadig driver software, and follow the instructions, manually running it as administrator. I’ve included some screen caps here so you know what you are doing a bit, but there is much better information out there if you need some hand holding. My dongle did now show up as “Bulk In” like you will see on the Zadig instruction pages, but after some installing, removing, and reinstalling a few times, eventually it worked. If I can give you one tip, it is that if SDR# gives you trouble, close it, plug in the dongle, and re-open it.
SDR#, pronounced SDR Sharp, is the leading free program to process SDR signals. It seems to be very processor intensive, so if you have an old or slow computer, you may want to try HDSDR. You will need to install Zadig and run it as administrator before you can use them.
I can’t speak to how different one dongle is from the next. As I’ll explain, I bought the more expensive dongles as well as the cheap ones, and that little blue one seems to be the most sensitive. There are now a couple versions of both the receiver and tuner chips, and one tuner chip is not even made anymore and has gotten very expensive to buy. If you want the latest chip and the temperature controlled tuner, and you want only a basic dongle, buy the RTL-SDR.com dongle.
Adding a Police, Fire, Military Scanner
SDR# is the most supported software partially because several people have written plugin programs for specific tasks. You can track satellites and download weather maps. You can decode digital voice signals, and the most important plugin I would say is the scanner and frequency manager plugin. You can’t watch more than a couple megahertz wide of frequency at one time, so using your computer to scan in frequency ranges, or scan a list of known frequencies, is a real gift.
To find your local municipality frequencies, you can use the online RadioReference.com. It is something of a Wiki, so it gets updated by the admins on a regular basis. Before the internet goes dark it would probably be a good idea to run all the frequencies for your local area and print them to actual paper, as well as save the pages to your computer.
What you will find if you try to go listen to existing traffic is that most public agencies have moved to some kind of digital “trunking” system. A trunking system controls a block of several frequencies, and splits up all communication over them as needed. That way everyone doesn’t need their own frequency, because not everyone needs to talk at once. They also tone code the radios, so even though the antennas on the police, fire etc., cars all pick up the same signals, on their relevant messages will come through the speaker of the radio. It’s pretty nifty stuff, but if you want to master it, you have to dig in and spend some time with the terminology and the technology itself. People are out there listening today, and all they did was figure out what other people explained.
All of the SDR# plugins can be found on one page at RTL-SDR.com, and
SDR Radio Antennas
Your dongle SDR will come with an antenna, usually connected with a tiny little connector. If you are at elevation, that little antenna outdoors will pick up a surprising amount of stuff, but you are much better to invest in an outdoor antenna and get it up as high as you practically can. The people at RTL-SDR.com suggest using a “Discone” antenna, and as you see from the pictures, I got one. It is head and shoulders above the tiny whip that comes with the dongle, and as multi-band VHF/UHF antenna, you probably can’t beat it. I went from unable to hear local police communications with the included antenna indoors, to able to hear everything, even the local airport, with the Discone only a few feet above the ground. For how much antenna you get, the $40-$60 standard Discone antennas are pretty good.
From a survival perspective, getting that antenna up in the air can be a risky proposition. A visible antenna probably isn’t as bad as visible solar panel to the risk of passing aircraft spotters, but it isn’t great either. I’m not going to bother covering those giant Yagi style Ham antennas, but if you want to go down that road, go for it. What I can share is that there are a ton of surplus 4 foot mast sections on Ebay, and they are much cheaper than a similar length telescoping mast. The telescoping masts are nice, but I don’t have a lot of faith in the ability of galvanized steel to retain the ability to telescope when left in the elements. As long as you have guy lines for the aluminum military poles, they will hold an antenna just as good. And it only takes one person to put them up, and you can get a tripod base for them on Ebay as well.
Also note that the Discone antennas claim to handle frequencies from 25mhz up to gigahertz, and that includes the 10 meter, or 30mhz Ham band. I didn’t get anything, using my Up Converter, which means you need an actual HF antenna if you want to work on the Ham bands. Oh yea, what’s an Up Converter?
Adding the HF Range
Haha! You thought that you were going to get away with ten bucks. Nope. But for ten bucks you can see if investing more is worth it, and in the meantime you’ll have a radio that will see and show you every frequency between 100mhz and 1.7ghz, if you can get the antenna up high enough. The dongle is pretty cool as it is, but if you want the frequencies below 100mhz, you need what is called an “Up Converter.” The receiver chip in the dongle gets all frequencies, but the tuner chip can’t handle anything below 100mhz. An Up Converter is a little device that takes the radio signal and converts it to the higher frequency that the dongle tuner chip can deal with.
The original concept seems to have been produced by a company called NooElec. They are now up to the 3rd version, because customers suggested improvements. I bought Ham it UP V 1.3 on Ebay, but then I realized that you don’t save anything from not buying it on their website. They have other add ons for the Up Converter as well, and I ordered them for a followup article.
But what I also found is that there are electronics suppliers in China who have copied that rather simple circuit and integrated them into standalone 100khz – 1.7ghz RTL-SDR radios. There are now lots of sellers selling several versions, all around the $50-$70 range, and in DIY kit form for as little as $30.
The two combo units I purchased are linked at the top of this article and there are several pictures here. I am still trying to figure out the difference between the two, if there is any. As you can see in the pictures, one has a switch to go between HF and VHF/UHF, and the other doesn’t. I assume the switch is just an antenna selector, and the one without the switch simply connects both antennas to the circuit without a switch, because someone apparently figured out that it was superfluous. These radios also come in an aluminum box, which is something you have to buy separate on NooElec for the regular dongle SDRs. If you plan to just get one of these and start rolling, I would suggest the one without the switch, and don’t bother with the $10 dongle. My connection wires have not come yet to try the Ham It Up converter with the dongles, but there will be more of these articles coming. Again, I’d like to just get this out there for my regular readers who may not have heard about it, and we’ll learn it together.
Antennas for HF
I picked the wrong do to stop sniffing glue when I delved into HF Ham antennas for my prior articles on survival radio. These days I have no less than a dozen of them, and I have yet to try all but two. My personal time, like yours perhaps, is divided among way too many things to spend a lot of quality time on one, but hey, if the SHTF, I’ll have a lot of stuff to try to figure out, and no internet to help me, which is why I buy printed books, which I’ll get to.
For my Ham backpack radio article I showed you some great antenna options for not a lot of money, but I recently figured out an even cheaper one. It is…drum roll please…, a piece of wire.
Radio waves and antennas are interesting animals. After a ton of reading, both online and from college level radio engineer books, I can assuredly say at this point that radio and antenna science may be old, but it is still evolving and probably quite young in terms of what they will eventually figure out. I have found that one little detail can make a difference between making contacts and not making contacts.
The key to the piece of wire is a little device called a “Balun” or some people call a similar device an “Unun,” Balun being much more prominent. That a Balun seems to do is bring the impedance of your single strand of wire antenna down to where your antenna tuner can dial it in. As long as the antenna is a correct length, usually longer than 1/4 of the wavelength, it is not uncommon to both hear and speak to to contacts from all over the world at favorable times in the atmosphere.
I found two really well reviewed Balun/Unun products on Ebay. The one based in the US is $37.99 shipped, and he has a video on the ad page that is pretty good. There are several sellers in China selling the same type of product, a 9:1 Balun, for just over $10. I have both on order and hope to do a real test with them soon with both the SDR and traditional low wattage radio.
I tried two antennas with my SDR on HF frequencies, and they do work, because I have Ham radios that can transmit and I tested them with HF signals. The problem is I didn’t get any signals from anywhere but a few feet away. Both antennas are what I would call gimmicky though. One is called the “Miracle Antenna” and it is no longer made. I looked around online, and it is little more than a Balun and antenna tuner built into one package, so with the stick antenna it wasn’t going to do much more than it did indoors. The other one is from http://www.mfjenterprises.com/. It is their 1621 mobile antenna that uses a regular stick and floats over the bands with an internal wandering lead to extend the length of the signal. What kills me is that I know with a little time and patience, and a little more research into cleaning up the SDR signal, the 1621 will work great. So please don’t take my extremely limited testing as a condemnation. I have about 6 different types of antennas from MFJ, and their SWR meter, so you’ll be seeing more of their stuff as I have time to work on these very involved articles on radio.
Dipole antennas are the other very low cost option, and they likewise can be made yourself, or purchased cheap from any number of suppliers. There is a guy from California on Ebay offering the different Ham bands in Dipoles for little more than the cost of the components. You can also just buy the middle and side insulators if you look around, then make your own wire connectors for the various bands. Each band requires a different length wire to meet the frequency resonance within the range of the antenna tuner. There are also a lot of wire-type multi-band antennas, some of which I have purchased and that were mentioned in my prior articles. At some point soon I’m going to get to them.
I discussed the most affordable automatic antenna tuners in my radio backpack article, so I am not going to return to that subject for now. Manual tuners are few, but there are kits right now on Ebay for under $20 that you need to solder. I’m going to try one.
Just be aware that when you are connecting radios to antennas to Up Converters to tuners etc., there are several different types of plug ends and you may need adapters. The little screw plugs on the Up Convertered SDRs and the Ham It Up are called SMA. Many of the low wattage antenna connectors are BNC connectors male and femail, and the larger coax plug has two names, the SO-239 and PL-259 for female and male respectively. The dongles come with several different types of connectors. The small one is called MCX, and the RTL-SDR.com website sells packages of adapters for both the MCX and SMA that are very reasonable.
Reading Up and Backing Up
Obviously I would buy the RTL-SDR book, but there are more books that you should get, because the internet is going to go dark at some point. However, let me premise that by saying that you also should download every piece of software for your radios you can find and put them on a thumb drive so that you can use them on any computer you may find. At some point I am going to do a “survival computing” article. One of the commenters on a prior article here turned me on to a “buck converter” you can get on Ebay that converts 12vdc to the 19vdc that your laptop needs, which is cool because you don’t need an inverter or an adapter to run your laptop from a regular solar storage or car battery.
If you didn’t already buy the Ham Radio for Dummies book, you may want to get that. If you wan to cut right through it all, the ARRL Ham Operating Manual is extremely specific in everything from what frequencies you can monitor to test your rig to the lengths of wire to use for the different bands on a Dipole. They have great information on communicating over packet protocols through a computer using a traditional Ham rig, but I didn’t find anything in that book on RTL-SDR, since it was invented about the same time as the book was published. There are plenty of books out their to help you get your Ham license, but as I warned in my prior articles, if you are under 50 years old and could potentially be drafted, I would not rush to get a Ham license for pure survival. They are going to start a war to cover up the mess, and nobody of fighting age will be exempt. You can listen with no license. If you can hear them, and you have transmit power at all, there is a good chance that in the same atmospheric window they will be able to hear you. These SDR radios don’t transmit, but I’ll be getting to some that do, as well as some other low wattage cheap worldwide transmitters.
So Much to Learn, So Little Time
I sincerely hope that we make it through this fall without this whole mess coming uncapped. But I don’t think we will. I can only get one of these articles out per week, and I have to divert to some more food topics, a good trauma pack, and a couple of nifty thermal power inverter products that will charge your phone while you cook dinner fr now. So while I will continue to try to make time to learn my radios, I won’t be back in this column with them for a while. If you want to dig deeper into SDR radios and other cheap alternatives, these are some of the things (besides the antennas) I am working on.
- Try the Ham it Up converter with its accessories from Nooelec. – They have their own 9:1 Balun product, and some noise filter accessories for their SDR.
- SDRs that transmit. – Low wattage radios are called QRP radios, and there are several SDRs out there that range from $89 to $300. I’m going to try a couple, but unless I am willing to get a Ham license, I have to find someone to transmit for me. What I like about the SDR QRP radios is that they cover a whole band of frequencies and not just a thin line of the actual Ham band.
- QRP DIY traditional radios on 40 meters. – If you search Ebay for QRP radio, you’ll see a number of electronics kit options from $10 to like $50. They range from a fraction of a watt to about 8 watts, which is plenty of power to reach out to Japan on a favorable night. These kits all transmit and receive n the 40 meter, 7mhz Ham band only, so they are extremely limited, but with a small Balun and a wire, you could theoretically establish a good communication with faraway family, if you do it now.
- Morse Code – Oy right? Well no actually. Morse code is not just an old and antiquated language. It is still used today in the Ham community, because it allows you to focus a small amount of power into a very thin band of frequency, which gives you literally worldwide reach. There are now Morse code readers, and even a keyboard typing translator from MFJ. If you live in New Hampshire and you have family in Montana, it would behoove you to get a couple of those 8 watt kits and a paddle, as well as the more advanced options.
Just like the stupidity of buying a few ounces of silver to “preserve” some of your cash, I don’t suggest that you invest in anything more than the $10 dongle if you don’t have a good supply of survival food. A 50 lb. bag of beans has 50,000 calories and is about $40. A 25 lb. bag of sugar is about $15. With a reliable supply of fresh water that’ll keep you alive for a couple months while the useless masses of sheep fight each other for the few crumbs they had in their pantries. Keep your head down, your lights off and your doors locked, and live. Down the road it wouldn’t hurt to have some electricity and communications, but that isn’t as important as food. This radio stuff is really cool, and it’s great brain food if you are an information junky like me. But things are getting nasty now and I don’t think it will be long.