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“What is the best SDR for those who are blind or visually impaired?”
I’d never been asked the question before, and replied that I’d have to do a little research. In truth, I suspected that research would turn up very little that was useful: after all, SDRs require a lot of pointing and clicking, and some of the interfaces are rather complicated. Spectrum and waterfalls displays, often at the heart of the SDR app, are visual displays.
But I kept thinking of my friend’s question. Upon my return, I set out to do a little research and possibly pose the question here on the SWLing Post. Then assistance stepped in…in the form of medium wave DXer Tore Johnny Bråtveit.
I reached out to Mr. Bråtveit via his website and asked for any advice he could give about SDRs for those who are blind or visually impaired. His enlightening response:
“In the interview I mentioned screen reader software and the need to find SDR software that plays well along with such screen reader software. For those visually impaired who have some eyesight, this aspect may not apply, since many of them are well helped by a screen magnifier software package.
For those without eyesight at all, or with so little left of the eyesight that they cannot make practical use of the screen, there are these screen reader software packages. They all do the same, but they solve the job in a somewhat different way and are good at different tasks.
I began using SDRs back in 2007. First I used some [RFspace] SDR-IQs for a few years, until I purchased a Winradio G31DDC in 2010. The user experience with Winradio was so good that I have stayed with those radios since then, using both G31DDC and G33DDC receivers at my remote listening places.
I think I can say that all the software packages delivered with SDRs have issues and challenges when it comes to using them along with a screen reader. The worst example of unusable native software I have seen so far, is the software package delivered with the [Microtelecom] Perseus. I had a thought purchasing one some years ago and make some scripts for my screen reader JAWS to see if I could make the Perseus possible to use effectively, but I dropped the idea at that time in favor of Winradio.
The SpectraVue software delivered with SDR-IQ was usable, but I had to script it quite extensively, especially to be able to use the timeline when playing back recordings. Also the frequency selector was a bit tricky, so I had to assign some hotkey combinations to it. Otherwise it worked fine.
The Winradio software for the G3x series works quite fine right out of the box. They have apparently thought [through] keyboard operation, and there are shortcuts for almost everything. Such shortcut keys are necessary, as navigating the program interface with a screen reader can be a bit too complicated, especially for those only using speech output from the screen reader to access the screen content.
I personally am living in a country where we have good access to refreshable Braille displays, which gives me the opportunity to turn off the speech entirely if I want and only use Braille output. This way I can navigate the program interface quite effectively to understand how things are laid out.
The only real issues I have had with Winradio software, is:
1. Changing shortcut keys:
Normally, the Tab key is used to move between elements on a screen, so it would be natural to think that pressing the Tab key will bring me to the next shortcut key definition. Not in Winradio. Tab can be defined as a shortcut key itself, so trying to navigate the shortcut keys dialog with that key gives you a number of options, all connected to the Tab key. My way around this was to navigate with the Braille display until I found the shortcut key definition I wanted to change, focus on it by pressing a cursor routing key in that position and changing the definition. Then navigate further down to the OK button and activate it.
2. The timeline:
The timeline used when playing back recordings can be hard to locate when using a screen reader, and even more difficult to work with, since when you press a cursor routing key on the Braille display to simulate a mouse click on it, the focus often moves to somewhere else on the screen. Then you have to work hard to locate back to that timeline again. My solution here was to script my screen reader with a hotspot at the timeline with a shortcut key assigned to it, so that I could move focus back there by pressing a key.
Among the third-party software packages developed for SDRs, I have found few that I can recommend. The only one I can think of, is HDSDR. Especially in the current version from November 2013, there are a number of useful shortcut keys, and the program seem to work very well. I have used it a bit with an AFEDRI SDR I have, and have also used it to play back older SDR-IQ recordings.
So, if nothing else works, Iwould say that HDSDR is the solution, since it is both easy to use and have support for a number of receivers. And it is free, as you certainly know.
[…]Please write back if I can help you any further”
Brilliant! What a treasure trove of information for our visually-impaired SDR listeners and operators. Thanks so much, Mr. Bråtveit, and please keep in touch with us here at the SWLing Post. 73s!
“I have continued to run A/B comparisons between my CR-1a and an NRD-515. Digital to Analog competition.
My NRD-515 has been a station favorite for many years. I find the two radios are pretty much equal in terms of performance. Sensitivity between the two are even. The wide range of BW filter options on the CR-1a are a real plus. My 515 has the stock 2.4 mechanical and the 500 hz cw filter.
The CR-1a with the portability, long battery life and internal speaker makes this one awesome receiver. I plan to use this radio when camping and recharging via a small solar panel should be a snap. A small QRP transmitter with T/R switching is the works.
I was really blown away by receiving an email from the president of Comm Radio concerning feedback I left on their website.
Big performance in a small package. 5/5+”
Thanks for your comment, Ray! Wow–The JRC NRD-515 is a classic. It’s great to hear that the CommRadio CR-1a stacks up so well against this benchmark.
Like you, I love the portability of the CR-1/CR-1a line. The internal battery powers it for hours at a time. I’ve hinted to CommRadio that they should design a small companion transmitter for portable QRP–link the two together and that would be one cool piece of kit!
Regular SWLing Post readers know that I’m a sucker for vintage radios––especially those of the WWII era. Indeed, I’m pretty much a fan of anything from the 1930s and 40s. I love the technology of that era and have an affinity for the culture and history, especially film and music.
Scottie (yep, I call her Scottie) produces beautiful, rich audio from her internal speaker. It’s truly an amazing piece of over-engineered technology that still sounds this good after 70 years.
Edythe Wright
Only a week or so after plugging Scottie into an antenna, my wife and I picked up a $1 CD at a church yard sale. The CD featured big band music from the late 30s/early 40s. Though we already had much of the music on the CD, we bought it anyway to keep in our car. One beautiful fall day, I was driving down a rural road and had the CD playing when a Tommy Dorsey recording of “The Music Goes Round And Round” with Edythe Wright on vocals, began playing. It had been ages since I heard this song…I then wondered how many GIs might have heard this song during WWII via GI Jive or the Armed Forces Radio Network. Perhaps they heard it on the Navy version of my Scott Marine radio, the Navy REH?
It was then I decided to finally pull the trigger and order a proper low-power AM transmitter for our home––something with which I could broadcast period music via my vintage gear.
There are a number of AM transmitters on the market, but the one that always stands out from the crowd is the SSTRAN AMT3000. My buddy, The Professor, has one and uses it to consume much of his digital audio content including podcasts and Internet radio stations. He sang the AMT3000’s praises, and I trust the Prof; he’s something of a medium wave guru.
Thing is, the AMT3000 only ships as a kit. In the past, this had stopped me from ordering the transmitter as I figured it was more than my beginner kit-building skills could manage. But after building David Cripe’s Ozark Patrol regenerative receiver, and loving the experience, I felt confident enough to make the order.
And, boy, am I glad I did!
The SSTRAN AMT3000 kit
The kit arrived within a few days of ordering it. Upon unboxing it, I felt like I had gotten my money’s worth, as it was packaged carefully in a quality box: components were clearly labelled in their own poly bags, the board was clearly marked with component numbers and the assembly/instruction manual was in a plastic binder, all clear and straightforward.
SSTRAN suggests taking your time building the kit, as there are a lot of components to solder, and you risk making mistakes that aren’t necessarily easy to remedy if you rush through the process. I tried to follow this advice––well, I intended to follow this advice. Thing is, I find it very difficult to put down a kit once I’m in the zone, so I zipped along a bit more quickly than I intended.
But it helped that SSTRAN took out a lot of the head-scratching and guesswork; the process couldn’t have been more smooth. I carefully checked and double-checked each component and marked it off the assembly list. First, you install all of the resistors, then capacitors, and on to other components. Other than having to hunt for some of the component locations on the board, it really was quite simple.
I started building the kit on a Friday afternoon and actually finished it the following Saturday morning. Much to my delight, after performing the tuning procedure, the transmitter worked on the first go. Whew!
Powerful (low power) broadcasting
The AMT3000 can be configured to work with the supplied simple wire antenna, which will essentially broadcast AM to radios throughout your home, or it can be configured for a Part 15 compliant outdoor base-loaded vertical antenna which will extend your range up to 3/4 of a mile, should your shack be down the road or in an outbuilding.
For the moment, I have my transmitter set up for in-house broadcasting only. If I ever want to build the base-loaded vertical, I only need to make a simple modification to the board to do so.
The supplied manual does a great job of explaining the best ways to maximize your signal, reduce any electrical hum and tweak your audio fidelity.
I’ve been using the AMT3000 nearly every day since I finished building it in mid-November. It seems to have a 100% duty cycle, does not overheat, and has no drift.
It produces high fidelity audio with a flat frequency response––and of course, with modulation and compression controls, you can tailor the audio to your particular taste.
Result? It sounds amazing piping WWII-era tunes through my Scott Marine SLR-M, Hallicrafters SX-24, and SX-99 and my Hammarlund SP-600.
As a bonus, I can hook my shortwave receivers up to the AMT3000 and listen to received audio via other radios throughout my house. Many times, I’ve listened to live broadcasts of ERT Open on 9,420 kHz via my kitchen AM radio…Very cool!
I set my transmitter to 1410 kHz, and have left it there. You’ll need to do a medium wave (AM) survey to find the clearest spot on your AM dial. I’m sure results will vary, depending on the level of medium wave broadcast activity in your area.
Here’s what my Scott Marine SLR-M sounds like playing “March of the Toys” by Tommy Dorsey and his Orchestra via the SSTRAN AMT3000 (note that this was recorded with just an iPhone, so audio fidelity is somewhat lacking):
Conclusion
If you’re looking for a high-quality, low-power legal AM transmitter, I highly recommend the SSTRAN AMT3000. Even if you’re a novice kit builder, with time and patience, you can successfully construct the AMT3000, too. If I did it, you certainly can!
If you’d prefer buying a pre-assembled AMT3000, they do occasionally turn up on eBay. Click here to search.
As for me, I’m happy to have achieved my modest goal of being able to broadcast 1930s and 1940s music to vintage radios of the same era.
AMT3000
10 kHz channel spacing for use inside North and South America. Includes enclosure and 120 Volt AC Adapter. The single surface-mount IC is pre-soldered on the board.
Price: $92.95
AMT3000-9K
9 kHz channel spacing for use outside North and South America. Includes enclosure and 120 Volt AC Adapter. The single surface-mount IC is pre-soldered on the board. *
Price: $92.95
AMT3000-9KNT
Same as AMT3000-9KSM, except the US-standard 120 Volt AC Adapter is not included. **
Price: $88.95
When I heard early reports about the new Tecsun PL-680, I was already wondering how it would stack up alongside other Tecsun portables. An early photo of the Tecsun PL-680 revealed how very similar it is, indeed, to the Tecsun PL-600, which has been on the market for many years. Moreover, the features of PL-680, which I heard about only a few weeks ago, sounded to me like a carbon copy of the venerable PL-660. I investigated further, and spoke with Anna at Anon-Co; she was given to understand that the Tecsun PL-680 was essentially a re-packaged PL-660 with improved sensitivity. I was curious enough about the PL-680 that I ordered one from Anna as soon as they were available, even paying for expedited shipping in order to have it in hand a bit sooner.
The Tecsun PL-660 has been on the market for several years now; it’s one of the most popular shortwave portables on the market. And for good reason: the PL-660 is relatively inexpensive, simple to use, packs all of the most vital and desirable functions/modes, and is available from a variety of retailers that ship worldwide. I have reviewed it numerous times and often used it as the basis for comparison with other shortwave portables. It’s China-based manufacturer, Tecsun, has emerged over the past few years as the dominant manufacturer of shortwave radios.
The Tecsun PL-680 looks like the Tecsun PL-600 body, with the Tecsun PL-660 features and layout. Indeed, the full complement of buttons, switches and dials are identically positioned to those of the PL-660.
Let’s cut to the chase…
Question: So, does the PL-680 have more functions than the PL-660?
Answer:No.It appears to be, and likely is, identical in every (functional) respect to the Tecsun PL-660. No surprises here, unless there are hidden features I haven’t discovered…!
Check out the following comparison photos–the PL-600 on the right, PL-660 in the middle, PL-680 on the right (click to enlarge):
The similarity is so striking, in fact, that I believe the PL-680 is the first radio I’ve ever turned on for the first time, only to find I immediately knew every function. I’m so familiar with the PL-660 that I could even use the PL-680 in the dark the first night I used it.
It also helps, of course, that the PL-680 is nearly identical to the PL-600, too, which I’ve owned for many years.
Here’s how I see the PL-680 product development equation:
In truth, I was quite disappointed that Tecsun did not add a line-out jack to the PL-680.
The PL-660, alas, lacks line-out, and though my Tecsun PL-880 has a line-out, its default shortwave volume is simply too high to be used by most digital recorders. I had hoped that the PL-680 might have a proper line-out jack, potentially making it a replacement for my trusty Sony ICF-SW7600GR. Unfortunately, this is not the case.
But other than missing a line-out jack, I really have few complaints. I’ve always been a fan of simple radio design and I believe Tecsun has done a good thing by keeping the user experience so similar in their PL-6XX line of portable shortwave radios. Apparently, a good thing is a good thing.
But here’s what everyone wants to know…
Question: Does the PL-680 have any performance advantages over the PL-660?
Short Answer: Yes! (But keep your PL-660.)
I should add here that I’m about to get rather technical and radio-geeky, so if you’re only interested in a summary, please skip to the bottom of the page.
Otherwise, help yourself to a cup of coffee, and let’s talk radio…
Shortwave performance
Since I spend 95% of my listening time on shortwave, I’ll begin with shortwave performance. Again, we’ll compare the PL-680’s performance with that of the PL-660.
In most circumstances, you’ll find that the PL-680 has better sensitivity than the PL-660. It’s a marginal improvement, but one I certainly notice on the shortwave bands–and so did the majority of readers who participated in the shortwave AM reception survey.
The survey had recordings from a total of three broadcasters: Radio Prague, WWV, and Radio France International.
The PL-680 was “Radio A,” and the PL-660 was “Radio B.”
The Radio Prague recording was quite strong and was the only broadcast in our survey in which the PL-660 and PL-680 ran neck-and-neck.
In truth, I believe strong signal reception on both these radios is excellent and nearly indistinguishable from each other.
Survey results from the WWV and Radio France International recordings showed a strong preference for the Tecsun PL-680. Again, here are the original recordings:
Based on comments from those who participated, the PL-680 came out ahead of the PL-660 in two respects: better sensitivity, and more stable AGC. In both sets of recordings, the signal was weaker than the Radio Prague recording, and QSB (fading) more pronounced. Herein lies a well-known weakness of the PL-660: soft muting and a sometimes over-active AGC equates to more listening fatigue.
Here is a chart with the full survey results based on 194 listener reports. The number of responses are represented on the vertical axis.
Obviously, the engineers at Tecun addressed the soft muting/AGC problem of the PL-660. In all of my time with the PL-680 on the air, I haven’t noticed any soft muting; the audio has been smooth and the AGC copes with fading much better than the PL-660. No doubt, these two improvements alone make the PL-680 a worthy portable for shortwave radio listening.
There is a downside to the improved sensitivity, however: the PL-680 has a slightly higher noise floor than the PL-660. This is mostly noticeable during weak-signal listening. Though I haven’t compared it yet, I’m willing to bet that the noise floor is comparable to that of the Sony ICF-SW7600GR. Personally, if increased sensitivity and stability means a slightly higher noise floor, I’m okay with that. I find that I listen better when the signal is stable and not fluttering/muting with every QSB trough.
Synchronous detection
The second survey focused on synchronous detection, which is a very useful receiver tool that mitigates adjacent signal interference and improves a signal’s stability. Perhaps it was my good fortune that the same day I tested synchronous detection, fading on even strong stations was pronounced at times. Perfect!
The first recording set was from Radio Australia, a relatively strong signal here in North America. Still, QSB was pronounced–making for an unstable signal–and there was hetrodyne interference in the upper sideband of the broadcast. When I switched the radios into lower sideband sync, halfway through, it effectively mitigated the hetrodyne in all of the recordings.
While I have always considered the PL-660 to sport one of the stronger sync locks in current production portables, it did truly struggle to maintain a lock in both the Radio Australia and Radio Riyadh recordings. Indeed, I was so surprised by how comparatively feeble the sync lock was on Radio Australia, that I disconnected the PL-660 from the recorder and moved to a different location to verify that something nearby wasn’t causing the sync lock instability. It was not; it was solely due to unstable band conditions.
It came as no surprise that survey respondents took note of the PL-680’s stronger sync lock: the PL-680 beat the PL-660 by a wide margin in both sample recordings. I chart the results, below, from a total of 85 responses:
Very good, PL-680! Someday I’d like to compare the PL-680 with the Sony ICF-SW7600GR, which I’ve always considered to have, among current portables, the strongest sync lock.
Single Sideband
I wasn’t able to provide an audio survey of SSB performance since the PL-680 picked up too much noise from my digital recorder to make for a fair contest.
Meanwhile, I’ve spent time listening to both radios in SSB mode and comparing the models. To my ear, both are very close in SSB performance, but again the PL-680 does have a slight edge on the PL-660 in terms of sensitivity and AGC performance.
SSB audio fidelity is very similar in both radios.
FM Performance
While I haven’t spent more than, let’s say, an hour with the PL-680 on the FM band, I have concluded that it is very sensitive–able to receive all of my benchmark local and regional FM stations.
An informal comparison between thePL-680 and the PL-660 also leads me to believe that they are both excellent FM performers and seemed to compare favorably. I would certainly welcome FM DXers to comment with their own evaluations of the PL-680.
Medium Wave Performance
I’ve also posted a medium-wave listener survey since many of you asked that I provide an evaluation of the medium-wave band.
In short, here is where the PL-680 loses to the PL-660: whereas, on the shortwave bands, the PL-680 is more sensitive, it lacks the same sensitivity on the medium-wave bands.
Though I believe the PL-680 does a marginally better job than the PL-660 of handling the choppy conditions of nighttime MW DX, the PL-660 still pulled voices and music out of the static and made them noticeably more intelligible.
The survey result swung very hard in favor of the PL-660, which has long been one of the more notable medium-wave performers among shortwave portables.
I provided a total of four sample broadcast recordings for comparison. Below, I have embedded one of them–a recording of 940 AM in Macon, Georgia, for your reference.
Survey results were definitive, with a total of 116 responses:
In all but the strong station sample (750 AM – WBS Atlanta), the PL-660 was preferred by a wide margin.
Summary
Invariably, all radios have strengths and weaknesses; here is a list of my notes from the moment I put the Tecsun PL-680 on the air:
Pros:
Excellent sensitivity and selectivity on the shortwave bands
Improved weak signal stability over the PL-660
Stable sync lock
Proven PL-600 form factor with good overall ergonomics
Great internal speaker–an improvement over the PL-660 (but not as good as the PL-880 or Sangean ATS-909X)
Other than medium-wave performance (see con), a worthy replacement for the PL-660
Excellent audio from the PL-680 internal speaker (improved over the PL-660, but not matching the fidelity of the PL-880)
Cons:
Medium-wave performance for is a step backwards from the PL-680’s predecessor, the PL-660. Okay on strong and moderate-signal reception, somewhat poor for weak signals
Marginal noise floor increase on the shortwave bands
Like the PL-660, lacks a line-out jack (Please note this, Tecsun!)
SSB frequency display on my unit is + 1 kHz, slight BFO adjustment is needed (details in this update)
Conclusion
If you’re a shortwave radio listener, you’ll be pleased with the Tecsun PL-680. In all of my comparison tests between the Tecun PL-660 and Tecsun PL-680, the PL-680 tends to edge out the PL-660, performance-wise. This coincides with the user surveys, too.
If you’re a medium-wave DXer, you might skip over the PL-680. That is, unless Tecsun makes a good iterative design improvement. If you’re a casual medium-wave listener, on the other hand, you’ll probably be pleased with the PL-680.
All in all, I like the Tecsun PL-680 and I see myself using it more than the PL-660 when I’m on the go. If you’re primarily a shortwave radio listener, the PL-680 may very well be worth the upgrade. At $95 US plus shipping, it is certainly a good value. Note that Anon-Co plans to post the Tecsun PL-680 for sale on eBay in March 2015.
PL-680 calibration: Dennis Coomans confirms via Anon-Co that the PL-680 (like the PL-660) can be calibrated by long pressing the AIR button (for SW, AM, etc) and by pressing SYNC for FM. According to Anon-Co, “all PL-680 receivers from production lines after November 2017 have this (hidden) manual calibration feature.”
Responses for these surveys has been, quite frankly, amazing! At time of publishing this post, we’ve received 367 individual survey responses!Thank you!
