Comment
Bravo for publishing Jack Weber's two-part article on Software Defined Radio!!! SDR is a field that I've been involved with since its civilian-applications inception back in the pre-Windows DOS era, and I'm pretty familiar with the current state of the art, having operated both a WiNRADiO 303e and a 313e now for almost a year.... and compared them quite extensively with close friend Guy Atkins Flex Radio SDR-1000. Jack Weber's article is the clearest, most thorough and well-written piece that I have read anywhere about these fabulous receivers. I wish that there were some sort of international prize for articles in the radio hobby, because this one would be a very clear winner. Thanks for the editorial fortitude that allowed space for such a long and well-illustrated review; you have done your readers an excellent service, because they are all now aware of the state of the art in this very important part of the future of the hobby.
Jack Weber and MWN win the International Article of the Year in my book!!
Jack referenced an "article" by me that has been reprinted several places. It was actually an overly long contribution to the IRCA e-mail group that was picked up from there. In case someone hasn't read it,
here it is in full:
Winradio G313e
I've been using the WiNRADiO 313E exclusively for DXing for the past year, plus. I love the radio and cannot imagine ever returning to a non-SDR receiver. Some of the main advantages of the WiNRADiO and its Flex Radio SDR-1000 competitor are probably only applicable to people DXing International MW and SW --- The Spectrum Scope, for instance, allows you to focus in from 20 kHz wide (max) to 2 kHz wide at total zoom-in. When you are working with close-together signals (say two or three kHz apart, there is nothing like seeing the signals and then graphically dragging the filter envelope and center-of-tuning to fit them precisely between the QRM to achieve the maximum recoverable audio.
The other thing that the Scope does is afford the user "situational awareness" to a degree that is just unreachable without a scope. Since you can see what you are trying to hear, in great detail, and you can see the immediate surrounding signals, too, you immediately know what adjustments need to be made to the receiver. It`s not that you can't figure out what needs to be done --- bandwidth, mode, slot filter, etc., in the traditional fashion --- its just so much easier and faster to do it when you have graphical as well as the traditional auditory input. This latter "situational awareness" aspect is something that would benefit Domestic DXers, as well.
Another situational awareness attribute of the 313E that I really love is the specific way that alpha-numeric notes can be displayed, after they are associated with a particular memory and frequency. For some years, there have been a few receivers on the market that allowed you to store a title or some form of notes with each memory channel. That way, WHEN YOU LOOKED AT THE MEMORY CHANNELS, there would be a title like "Mem 1 BBC Evenings 5975 USB" or "Mem 2 R Australia 9580 AM." Well, the 313E does that, too, but in addition, it allows you to associate a comment with each memory. Further and very importantly, it displays that comment just beneath the Frequency Display on the radio, WHENEVER the receiver is tuned (by any means) to that frequency, whether you are in memory mode or not. So, when I have my "Asian MW" memory file loaded, every time I tune past 891, the comment appears just beneath the Frequency numbers on the radio WATCH FOR THAILAND LATE. When I go to Grayland this weekend, when I pass 738, the radio is going to remind me: RECORD PROBABLE JILIN PBS, etc., etc. This ability should be of assistance to domestic DXers, too. Having reminders come up every time you pass certain frequencies is a boon to this 65 year-old DXer, let me tell you!
Two other special favorites and then I'll quit:
The synchronous detector is the best that I've ever used. In fact, though I've owned most of the receivers with a sync detector, this is the first that I've used as my primary DXing mode. Two reasons --- first,
by being synced on the carrier of choice, it actually suppresses some sideband splatter and hash from adjacent signals (wow!) further, even with signals out in the open, it seems to improve signal-to-noise or
intelligibility of weak signals. In my Okie terms, "It hears better!"
Lastly, an attribute of most serious DSP receivers --- virtually vertical sidewalls on the IF envelope. With any analog IF filters, even the vaunted Collins mechanical filters, the actual window that you are receiving
the signal through is shaped like a truncated isosolese triangle. Where your main DXing filter may be 2.7 kHz wide at 3 dB down, it may be 5 or more wide at 30 dB down. The result of that is that you use narrower
filters that you really want to, to conquer adjacent channel QRM --- AND since you have to use a wide enough filter to let intelligible audio in, you also allow loud adjacent splatter, etc. in "under the filter skirts." With
a total DSP package, from demodulation on down, the IF filtering, of course, is done in the software. Hence, filter skirts that are pretty-much VERTICAL. In my case, I can use say a 4 kHz wide virtual filter rather
than a 2.8 physical filter in the same conditions.
Since my 4 kHz filter lets in much more of the audio of my DX target (than does a 2.8) I hear more intelligible audio. This would be true, all things being equal, of any set that used virtual IF filters, not just the
Black Box receivers like the 313. Purists will argue that other problems in the digital realm degrade this advantage, and to a degree, they are likely correct. However, I can still keep my filters open wider with this
radio than with any of the excellent analog sets that I've owned.
So, while the 313 black box won't be to everyone's taste, it lets me hear more stations, better and easier than any set I've ever had before. I may someday buy another main DXing set, but I'll guarantee you that it will be a software-defined receiver.
P.S. I started MW DXing in the winter of 1953-54 and I love to use classic tube communications gear. I especially love sitting and staring at it while I listen and MOST OF ALL, I love tuning a really well weighted,
gear driven tuning knob. For years, I owned a mint 1942 SX-28A. Tuning that set was almost a sexual experience. I sold the SX-28A to help me afford a totally rebuilt SP-600 --- turning that counter-weighted knob
and those beautiful brass gears WAS orgasmic. I love DXing with those sets, and I was so sure that I'd miss a tuning knob on the 313E that I invested in an outboard accessory tuning knob (USB connected) that I
used for about three evenings. I can just hear more stuff more easily with this cold little box; and, in the final analysis, my hobby is hearing DX and getting QSLs, not turning knobs, counter-weighted or otherwise,
John H Bryant. USA 27th November 2006
