Below, London Shortwave shares a guest post (also viewable on his blog) which describes in detail his design for his portable SDR around the FunCube Dongle Pro+ and an 8″ Windows tablet, and explains how effectively it works for him. This post includes recordings and a video; it’s an excellent tutorial:
At the outset, I thought that all that was necessary was a tablet (I chose Toshiba Encore 8″), the FunCube dongle itself and just some antenna wire. This turned out to be a naive assumption because the tablet’s USB interface injected enormous amounts of radio frequency interference (RFI) into the SDR, making listening on some shortwave frequencies essentially impossible. Just to be sure that I wasn’t being plagued by a defect of my chosen tablet model, I tried out the same set-up on a Dell Venue 8, with identical results.
To deal with the issue of tablet-generated RFI, I bought a galvanic USB isolator, which, in essence, is a box that breaks the electrical connection between the USB dongle and the tablet’s USB interface while allowing USB data to pass through in both directions.
Heros Technology galvanic USB isolator
Additional power for the SDR
The isolator resolved the RFI issue completely, but created another problem altogether: the device specifications state that the isolator’s power output is restricted to 100mA at 5V. This is sufficient for USB devices that are self-powered but not for the FunCube dongle that draws all of its power from the USB port to which it is connected.
USB Y cable
One way to supply extra power to a USB device is to use a “Y-cable”. Such cables have one extra USB plug that can be attached to a source of additional power (for example, a USB power bank). This solution is commonly used to connect power-hungry items, such as large hard disks, to low-power, portable computing devices (laptops and tablets). Having bought this cable, my next step was to find/improvise a battery that meets the USB power specifications (5V, 500mA).
Yet more interference
My first thought was to use the mobile USB power bank that I use to charge my iPhone while on the go. After all, it already has a USB port and supplies power with the right voltage. Once again, my expectations were confounded and RFI reared its ugly head! The power bank radiates significant interference into the circuit because it uses a switching regulator to maintain steady voltage. Luckily, I came across Gomadic’s portable AA battery pack with regulated 5V output that emits way less interference than any of the other USB batteries I tried (my intermediate solution used 4 rechargeable AA batteries and a makeshift USB connector, and although this resulted in zero additional interference I decided that it’s not safe to supply the SDR with unregulated voltage that doesn’t match the rest of the circuit). I used the handy passthrough USB voltmeter I bought in Maplin to check that Gomadic’s nice-looking gadget does indeed give out 5V as advertised.
So, what can one do with the remaining RFI from the additional power supply? It turns out that it can be mitigated quite effectively by inserting a balun (item 10 on Figure 2) between the SDR and the antenna wire (item 12). The balun is connected to the SDR with a coaxial cable (the “feed line”, item 11). Additionally, ferrite choke rings (item 9) attached to the feed line help reduce this RFI further: winding the feed line through the choke rings several times is sufficient. However, neither the balun nor the chokes are effective enough to replace the USB isolator! It appears they only help with the noise generated by the power supply, which is relatively minor anyway.
Cost vs Portability
When SWLing Post published the details of my intermediate solution, Dennis Walter – one of the engineers behind Bonito RadioJet – popped up in the comments section and suggested that my setup is too tedious, as it involves lots of cables, and that his SDR is superior in terms of portability and the supplied software. While I haven’t had the chance to evaluate RadioJet, I pointed out that the cost of his radio is significantly higher than that of all of my components put together. I also mentioned that the free SDR# software I use is superb: it sounds excellent and offers a number of features that many software packages and conventional radios don’t have. So, having finalised my design, I thought that it might be time to tally up the cost and listen to the results.
Adding up the prices of items 2 – 12 (and excluding the optional voltmeter) brings the total cost to $449 vs. Bonito RadioJet’s $689. For the price difference you can throw in the Toshiba tablet at $194 and still have some change, enough to buy a carrier bag and perhaps even a nice pair of headphones!
Figure 1. Radio components
Figure 2. Antenna components
In terms of portability, the entire setup fits nicely into an 11″ laptop carrier bag.
Figure 3. Packing the components into an 11″ carrier bag
Figure 4. Ready to go
Setting things up in the field is not particularly cumbersome, either:
Figure 5. Portable SDR setup in action in a local park
As for the results, listen to the below snippets and be the judge. The only thing I will say is that none of my other portable radios have ever given me this kind of performance, not even with the long wire antenna attached:
At one point I wanted to build an enclosure to house the FunCube dongle, the power supply and the USB isolator in a single tidy unit, but I no longer see the need. It’s easy to pack all of those items into the carrier bag and also they are all useful individually: the USB isolator can be paired with other SDRs, and I recently discovered a neat additional use for the Gomadic battery pack.
Well, that brings me to the end of this post. I hope my design will inspire you to come up with your own portable SDR system, and that you will share your results with me in the comments section. Happy listening!
One of the most popular posts on the SWLing Post each year is the annual Holiday Radio Gift Guide. I started this annual post in 2010 when I realized that it would be easier than answering an in-box full of individual emails from people seeking the perfect shortwave radio for their friend or loved one.
In the following, you’ll find a handful of select radios I recommend for this gift-giving season. I’ve arranged this selection byprice, starting with the most affordable. I’ve included a few promising new radios that have recently been introduced to the market, along with models that have proven their reliability and are on their way to becoming classics.
For the benefit of those with less radio experience, this quick guide is basic, non-technical, and to the point. For more comprehensive reviews, please consult our Radio Reviews page.
Updated for the 2012-13 holiday season on 22 November 2012.
Simple, affordable and portable
The Kaito WRX911 is a classic, no-frills analog radio. Turn it on and tune. That’s its game.
Kaito WRX911 or Tecsun R-911 ($33)
I’ve owned this little radio for years. It has been on the market a long time and I know exactly why: it’s affordable and very simple to operate. While it has no tone control, bandwidth control or digital display, the WRX911 performs better than other radios in its stocking-stuffer price range. I find its medium wave (AM band) reception above par–especially its ability to null out interfering broadcasts by simply turning the radio body. The WRX911 is also a great radio to keep in the glove compartment of your car. (Another similarly-priced radio to consider is the DE321, which we recommended last year–also check out our review.)
No matter where you live,you should have a self-powered radio in your home. The Eton FR160 is like a Swiss Army Knife when power fails.
Eton FR160 ($34 US)
A good friend recently sent me a message: she had been without power in the wake of Hurricane Sandy for two full weeks. She also added that her little FR160 kept her family informed and provided comfort in the dark days following the hurricane.
The Eton FR160 is a sturdy and useful little radio. This radio features AM/FM and the NOAA weather radio bands (at least, the North American versions do; international versions may have shortwave instead of weather frequencies). The FR160 also features a very bright white LED flashlight and even sports a small solar panel that can effectively charge the internal battery pack. The FR160 also features a USB port that you can plug your mobile phone, iPod or other USB device into for charging. (Note that it takes a lot of cranking to charge a typical cell phone, but I can confirm that it does work in a pinch.)
Over the past few years, these radios have become ubiquitous. I’ve seen them in sporting goods stores, RadioShack (Tandy in some countries), BestBuy, Target, Bed Bath and Beyond–indeed, they’re in practically every North American big-box store and in many mail order catalogs besides. Of course, Universal Radio sells them, too.
The CC Solar Observer has everything you need to weather a power outage
CC Solar Observer ($50 US)
Like the FR160, the CC Solar Observer is a wind-up/solar emergency radio with AM/FM and Weather Band, and an LED flashlight built into the side of the radio. It’s perhaps a nicer option for those who want bigger audio out of their emergency radio. The Solar Observer is rugged and well-designed, like many C.Crane products.
When coupled with another Bluetooth device, this radio doubles as wireless remote speakers
The Tecsun PL-398BT($100)
The Tecsun PL-398BT is a very unique shortwave radio. In fact, it may be the perfect gift for a radio enthusiast who is also very tied to their computer or smart phone. Besides being a very capable shortwave/AM/FM receiver in its own right, when put into Bluetooth mode and connected to a smart phone, PC, or other device, the PL-398BT’s speakers act as its wireless stereo speakers. I believe this may be an ideal way to listen to internet radio from your iPhone, for example. Of course, the PL-398BT comes from a legacy of great receivers, so the AM/FM and shortwave performance will not disappoint. It’s a little on the pricey side for a shortwave radio that lacks the SSB mode (for listening to utility and ham radio transmissions), but the Bluetooth function more than makes up for it, in my opinion. Some people may definitely prefer this function.
The Grundig G3 has a solid reputation and at $100, great value for the performance.
The Grundig G3 ($100 US)
Simply put, the Grundig G3 offers the best bang for your buck in 2012. I have a lot of portable radios, but the one I probably reach for the most–for recreational shortwave radio listening–is the Grundig G3. I wrote this review three years ago and even recently posted this update. Read them and you’ll see why I like the G3. At $100, the G3 will please both the shortwave radio newbie and the seasoned listener.
The Grundig G3 can be purchased from Universal Radio or Grove. Some local RadioShack stores also keep the G3 in stock (though unfortunately, less often than they used to).
If $500 is within your budget, and you’re buying for someone who would love combining their radio hobby with computer technology, a software defined receiver (SDR), like the RFSpace SDR-IQ, will certainly exceed their expectations. There are many SDRs on the market, but the SDR-IQ offers the most bang-for-the-buck in the SDR line (though the WinRadio Excalibur ($900 US)–which we recently reviewed–and the Microtelecom Perseus ($1,000 US) are certainly pricier benchmarks worth considering).
The RFSpace SDR-IQ is available from Universal Radio and is manufactured in the USA.
The Bonito RadioJet
The Bonito RadioJet ($700 US)
The Bonito RadioJet is new to the North American market in 2012. I reviewed the RadioJet this summer and even traveled with it extensively. I was thoroughly impressed with its portability, performance, and it did not task my PC as much as SDRs do. Like the SDR-IQ, it’s a small black metal box that hooks up to your PC to unlock its impressive features. The RadioJet, though, represents cutting-edge IF receiver design, and comes with an amazingly versatile software package. If you’re buying for someone who likes versatility and raw performance–and likes being an early adopter–the Bonito RadioJet may well be the perfect fit.
The Bonito RadioJet can be purchased from Universal Radio and is manufactured in Germany.
We featured the Alinco DX-R8T in last year’s holiday gift guide. We also gave it a full review–in short, this radio thoroughly impressed us. It’s full-featured, performs well, and comes at a very affordable price. If you’re buying this for a ham radio operator, they’ll understand the reason why the Alinco DX-R8T needs a 12 volt power supply and an external antenna. It’s a receiver version of a ham radio transceiver, and as such, does a fine job on SSB modes.
Bonito’s Dennis Walter at the Bonito booth in Hara Arena at the 2012 Dayton Hamvention
At the Dayton Hamvention this year, I met Dennis Walter, who is with Bonito, German manufacturer of the 1102S RadioJet. Dennis was kind enough to loan us a radio for review on SWLing.com. I have been evaluating the Bonito 1102S RadioJet over the course of eight weeks and have formed some impressions about its performance. And while I haven’t made any A/B comparisons yet with either the Microtelecom Perseus or the WinRadio Excalibur–both on my review table at the moment–I have taken the time to get to know this lean, high-performance IF receiver.
The RadioJet box (left) is about the size of the highly portable Tecsun PL-380 (right)
When I first held the RadioJet, I was amazed at how small and sturdy the unit is. It’s built quite well; I expect you would have difficulty putting a dent in its aluminium body. It has a very small footprint on the desktop and fits very easily in my suitcase. Specifically, the RadioJet box is about the size of the highly portable Tecsun PL-380—in fact, the PL-380 is slightly wider than the RadioJet.
And though I knew about this feature in advance, what really stands out is its lack of dependence upon a power cable or a DC-in jack on the back of the unit. Indeed, the only two connections are a USB port and a female BNC connector for the antenna. The RadioJet derives its power directly from the USB cable. This is a major plus, providing additional freedom, as there’s no need for an external power supply or “wall-wart” type DC adapter. With the radio and USB cord, you’re ready for radio on-the-go—as I was on my recent DXpedition family vacation, when I reviewed the RadioJet.
Plug and play
Installing the RadioJet is very simple. You simply plug the receiver into your computer via the supplied USB cable, then install the RadioJet software via the supplied installation disc. As far as I know, the RadioJet software only works with Windows PCs. I tested the RadioJet with my Toshiba Satellite 64 bit Intel core i3 laptop computer.
I had no difficulty getting the RadioJet running. Indeed, it worked after the first software install. In my experience, it was true plug-and-play.
Is the RadioJet an SDR?
To be clear, the RadioJet is technically not an SDR, it is an IF receiver, more like the Ten-Tec RX-320D. I’ve certainly been guilty of calling it an SDR in the past as it’s easily to lump it in the same category. Within this review, I do compare RadioJet features with SDRs currently on the market since it is software (PC) controlled, has many of the same features as an SDR and directly competes with them.
Software and Usability
Unquestionably, the Bonito 1102S RadioJet’s software offers the most flexibility of any Software Defined Radio (SDR) or IF receiver I’ve ever reviewed.
A screen capture from my Toshiba Satellite Windows 7 laptop (click on image to enlarge)
Having used several SDRs and IF receivers–including the Microtelecom Perseus, Ten-Tec RX-320D, RFspace IQ and WinRadio Excalibur—I can state that the basic functions of the RadioJet are comparatively easy to locate. The graphic user interface (GUI), however, could appear somewhat complicated, particularly if you are new to software based receivers. While I like options and the ability to customize a user interface to best match my preferences, having a GUI that is both highly-adaptive and full-featured can be a double-edged sword until you become accustomed to it.
On one hand, you can customize the RadioJet GUI more completely than any other SDR I’ve ever used: you can change the window size, layout, spectrum display, and color palette; you can also load pre-designed screens to help with signal measurement, IF control, and AF control. Indeed, the RadioJet’s designers have also included a unique “Scanner and Signal Utilities” screen for working with utility reception.
On the other hand, there is a learning curve in both customizing the GUI and familiarizing yourself with the radio’s controls. This is why I wish the RadioJet had a proper owner’s manual. Early in my experience with the unit, while making setting modifications during a broadcast, I found I could lose my place within the control settings or accidently alter a setting that would result in degraded reception (such as the WAV volume, AGC, DSP or attenuator). I thought that the RadioJet was malfunctioning, only to discover that I had a setting adjusted incorrectly. Note that Bonito’s online support, however, has been very responsive in helping me when this happens.
The RadioJet GUI is the most flexible and adaptable of any software radio I’ve used
Fortunately, Bonito is fully aware that many listeners could be overwhelmed by the various options the RadioJet offers, and have designed the GUI so that if you minimize the window (as you would any Microsoft Windows “window”), only the basic receiver options will display.
The only major drawback I’ve observed with the RadioJet, as fellow reviewer Fenu mentions in his comprehensive review, is that its software still has a few trouble spots to be ironed out. This is not surprising, considering that is very new to the market. To be clear, software is a very important part of an SDR or IF receiver’s usability: after all, its interface is software defined. An SDR or IF receiver without the software is merely a small paperweight–but with it, becomes highly functional radio with a performance that can be enhanced with upgrades over time.
The success of the RadioJet over time will be directly tied to the responsiveness of Bonito to customer feedback. Like Fenu, my experience with Bonito is quite encouraging in this regard—Bonito has even provided remote desktop help sessions for individuals, and I can personally vouch that I’ve benefitted from this support. Bonito also closely attends to discussions on the RadioJet Yahoo Group, indicating that the company is listening to their customers. Bonito has been updating the software regularly—in fact, they’ve just added a noise blanker to the software which, I hear, effectively deals with electrical pulse noises like those produced by electric fences.
Though not required, if you don’t already have a mouse with a scrolling wheel, you will want one to tune and adjust the RadioJet. Band-scanning is pretty straightforward and there are a variety of methods to adjust the frequency:
Hover your mouse over the tuning knob and click to rotate clockwise or counter-clockwise
Hover over the digital frequency display and use the mouse scroll wheel to adjust each digit of the frequency up or down
If the display is expanded, there is also a number pad where you can click on each number to adjust
In the current revision of the software–much like with the Perseus–you cannot directly key in the frequency with the number pad of your computer
With the scroll wheel of the mouse, you can easily adjust most settings and filter controls of the RadioJet. It acts, in a sense and in most cases, as a proxy for a tangible knob you would have on a traditional radio. I imagine there are other (perhaps even better) peripherals that would work, too.
I do find the controls a bit frustrating to manipulate if you do not have at least a mouse with a scrolling wheel. I did not bring a mouse on my recent DXpedition and later regretted the decision. The track pad on my Toshiba laptop does not offer the accuracy and scrolling features needed to fluidly operate the RadioJet GUI.
The RadioJet audio recording and playback panel
Unlike a lot of SDRs on the market, the RadioJet does not have the ability to record large chunks of HF spectrum. For example, the WinRadio Excalibur and Microtelecom Perseus can record 2,000 kHz of spectrum; the RadioJet, however, is limited to 24 kHz. I asked Dennis at Bonito about this and he said that when designing the RadioJet the designers focused on the performance of the received signal and the radio’s overall efficiency rather than upon having a wide IQ output.
Bonito is catering to the discriminating DXer who is seeking the highest quality signal upon receiving, even among weak signals, but who is less interested in spectrum recording. Personally, I like to record and archive spectrum, but I do appreciate this focus upon delivering the best possible received signal, even with a very modest computer. Indeed, unlike most other SDRs on the market, the Bonito 1102S RadioJet reportedly works well on Netbooks with Atom processors. I can say that my Intel Core i3 laptop runs the RadioJet beautifully. I do plan to try the RadioJet on my netbook soon, as well.
RX and DX modes
One unique and highly-promoted feature of the Bonito 1102S RadioJet are the RX and DX “Channels” or operating modes. On the Bonito site, they show an example of a very weak signal showing up on the spectrum display, almost totally hidden in the band noise. When the user switches to the “DX Channel,” however, the noise floor drops and the received signal pops out, and becomes armchair listening.
I have found that the DX Channel is indeed very effective at pulling a weak signal out of the noise. The RX Channel, on the other hand, does an even better job of receiving stronger broadcasts signals. The channels appropriately balance AF and RF gains along with the raw IQ to deliver the receiver’s very best under prevailing conditions.
The RadioJet RX/DX channel selection panel
I find that I switch between the two channels rather frequently, and tend to do so manually. There is a setting in which the RadioJet will automatically determine what settings should be used to best hear the target broadcast—it switches very quickly between the RX and DX Channels and even makes small adjustments to the AGC and other settings. Though quite effective, I still prefer to manually adjust these features to enjoy greater control of them.
Digital Radio Mondiale (DRM)
This is perhaps one of the most fluid and flawless features of this radio. Though I have not had an opportunity to record DRM yet, I have decoded several broadcasts with great success (REE, Vatican Radio and RNZI).
In fact, if you are looking for a an excellent DRM receiver, the RadioJet may be your best bet. Unlike many SDRs on the market, the RadioJet decodes DRM natively: in other words, you simply tune to a DRM signal and change the mode from AM to DRM. That’s all. Your software already has a built-in, paid-in-full decoder (no need for a costly plugin or DREAM license). It’s the best implementation I’ve ever tried.
When I begin a radio review, I keep a checklist of pros and cons as I discover them. In this way, I can remember my initial discoveries.
Here’s my list from the Bonito 1102S RadioJet:
The RadioJet derives its power from the supplied USB cable, the only two connections are the USB port and the antenna (BNC)
Excellent sensitivity and selectivity
Low noise floor
Excellent DRM implementation
Customizable filters—some can actually be hand-drawn with the computer mouse to accomodate received signal conditions
Though I haven’t done an A/B comparison with the Perseus yet (coming soon!), but like Fenu, I expect the sensitivity and selectivity to be very similar
Operates without a separate, external DC power supply
Software and GUI are extremely customizable—the most flexible and resizable I have used (see con)
Audio fidelity, once adjusted, is excellent
Two modes of listening (RX and DX channels) allow for either manual or automatic settings for strong or weak signals (see con)
Technicians and support representatives from Bonito have been responsive to customer requests and feedback
Software updates are frequent and occasionally include new features
Since the RadioJet doesn’t use or have to process wide IQ, (see con) its 24 kHz bandwidth targets one broadcast and places emphasis on clean RX performance
Doesn’t require robust PC processing power, will even run smoothly on a netbook (per manufacturer—though I will test soon)
Scroll wheel on a standard PC mouse acts as a nice proxy for the many control knobs on the RadioJet GUI (see con)
The RadioJet software even has a unique map display of broadcasting schedules
Software has some bugs and is not yet fully mature
Software and GUI are so customizable that they reqire a learning curve—could be a negative for SWLs seeking simpler functionality (also see pro)
No IQ output like the Perseus, WinRadio and RFspace SDRs, which allows for wide spectrum recordings (also see pro)
Software occasionally crashes
Sometimes when switching between RX and DX Channels, WAV volume settings are altered and not returned to original settings, resulting in a “splattered” or “hot” audio sound
Software controls are frustrating to use without a mouse—or by using a laptop track pad only (see pro)
Lack of a proper owner’s manual
Overall, I like the Bonito RadioJet; I would certainly recommend it for the shortwave radio listener and DXer, especially one who wants:
robust receiver control software package
good value for performance
I would also recommend the RadioJet to those who don’t want a receiver to task their computer’s processor excessively.
If you are looking for a mature, simple software defined radio—or if you need wide spectrum recording–you may want to check out a true software defined radio (SDR) from WinRadio, RF Space or Microtelecom.
In my opinion, the only drawback to the RadioJet, as of time of this review publication, is that the control software is not yet refined and still has a few bugs. None of these limitations have affected my ability to use the RadioJet, but they have proved annoying at times.
My impression of Bonito and their staff is that they are trying in earnest to respond to customer feedback and focus on delivering an effective receiver for the DXer and for those wishing for excellent performance on a budget.
If this attentiveness continues, the RadioJet should only improve with time.
The US price tag for the Bonito 1102S RadioJet is $689 through Universal Radio. This is fully $300 less than the Microtelecom Perseus. If you want serious performance, from a lightweight, rugged, flexible software controlled receiver, you should be pleased with the RadioJet.
UPDATE: Want to hear a broadcast recorded on the RadioJet? Check out my previous post on the final broadcasts of RNW. The RadioJet did an amazing job pulling this station out of the static.
Follow our tag “RadioJet” for updates to this review and future A/B comparisons with other receivers.
Keep in mind…
SWLing Post regulars know that I don’t post highly technical or “laboratory” reviews. Take this review as my experience as an experienced shortwave radio listener, where I focus on usability, receiver quality, and audio fidelity, and provide general operating notes. I also focus on helping consumers make purchase decisions, as I outline the pros and cons of each receiver. For a more technical review, I would refer you to previously-mentioned Fenu’s review and–potentially upcoming–Rob Sherwood’s receiver performance data.
After reading Fernando’s review of the RadioJet–where he compared it to the Perseus–this may be one of the best SDR performers for the price. We will be reviewing the Bonito 1102S RadioJet in the near future as well.
To follow all updates of the Bonito 1102S RadioJet, please follow our tag: RadioJet
The Bonito 1102S RadioJet SDR (software defined receiver) now has FCC approval. This means that the RadioJet will be available for purchase in the US.
We will be reviewing the RadioJet in the near future. I, for one, can’t wait–especially after reading Fenu’s review. If it has Perseus performance at a much lower price point, this could be a very competitive receiver.