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I stand corrected. I have not looked closely at the Softrock models that could be purchased since I gave mine away, I had noted the Ensemble II was wider banded, but did not know it was full band. The web page I looked at (Ensemble RX II Builders' Notes) for the Softrock Esemble II only listed the freqs as Band 0=1.8-2.0, Band 1=3.5-7.3, Band 2=10.1-18.168, and Band 4=21.0-29.7.
However, looking at the schematic the rest of the design, including the front end, basic BPF (although mine was a single BPF instead of four selectable ones), QSD, and QCG are all identical to the Softrock that I had (I believe an SR Lite II), so other than bandwidth the performance should be identical.
Unfortunately the Softrock surpassing the RX320D or the R-75 is not supported by any testing I am aware of.
The Softrock with no external added preamplifier is considered to have a noise floor of between -108 and -112 dBm, depending on what source is quoted (not withstanding the occasional -123 to -140 claim on the Softrock Yahoo group...yes, I am a member). Except for the V9.0 kit, claiming “at least” –120 dBm, but not independently confirmed that I can find. I also expect it depends on who built the kit.
The RX320D has been measured to have a noise floor of -124 dBm, some sources quote more like -126 dBm. The Icom R-75 has a noise floor of -123 dBm with preamp off, and -130 dBm with preamp on.
This means that both the R-75 and the RX320D will have an extra 3 or more dB on the Softrock, possibly as much as an extra 22 dB. In its simplest form this means the Softrock can not see as far down as the other two, as long as the natural noise environment allows it to be used.
The RX320D has a sensitivity of 0.3 microVolt (for 10 dB SN). The R-75 has 0.2 microVolt. The Softrock is variously quoted as about 0.6 microVolt. Again meaning the Softrock does not stack up to the other two.
And we have not discussed phase noise yet. While the Softrock is pretty good with the Si570 osc it is still not up to the levels found in the R-75.
However, the Softrock, and ALL SDRs, are going to kill the RX320D and the R-75 in the areas of narrow spaced dynamic range, filter ultimate blocking, and filter adaptability. That means that when you have two close spaced signals any SDR; as long as the code is written well, can outperform even the very best, mutli-thousand dollar professional conventional radio.
However, lets forget all of that, call all of the radios the same in noise floor and sensitivity, for the rest of this discussion. And accept that SDRs do some things better than conventional radios.
As far as the $300+/- RX pulling ahead of the $600+/- RX, that is debateable, however the $300 one will definately not do it without a $300+ computer attached. It is an apples and oranges thing. The two are roughly equal, but one will operate all by itself and is thus more complex, changing the cost and value.
Yes, I know any SDR will also need a computer, but I was addressing the cost comparison of the RX320 to the R-75. Add the required minimal equipment for operation and the cost delta is completely gone, if not turned in the other direction.
Yes, the Softrock is impressive, particularly for what it cost, it is outstanding for the cost. 25 years ago if you had described its abilities to me and told me the price tag I would have asked if you had had a drug test recently. The RX320D is also impressive, although it cost slightly more. The R-75 is in the same boat, but able to be used stand-alone.
If you are asking about listening to a single frequency, and the MDS and sensitivity numbers above are correct, then yes the other radios will indeed “sound” better than the Softrock when operating at marginal levels in a low noise environment. Naturally not when the signal is strong enough to achieve a decent SNR on the Softrock or if the natural noise floor is high enough so that the advantage of the other radios cannot be used. Of course, such a claim is always arguable, what does “better” mean? However, you are missing part of the ride here as far as SDRs are concerned, it is not about physical knobs or virtual knobs, or all about sounding “better” (of course, all of those things can be factors).
First and foremost, can the Softrock display 1 MHz of bandwidth to assist you in finding new and interesting signals? No. If you have the very best sound card possible it can display 190 kHz, when I used mine I got 48 kHz with the best results (could go more but 48 kHz seemed to work out best, and I never bothered to upgrade the sound card) and most users I know of are dealing with about 96 kHz max. And the WinRadio Excalibur will display up to 50 MHz at one time, more than 250 times the max possible instantaneous display window of the Softrock. As I have said before, you can see every single signal that pops up above your noise floor, across the entire HF spectrum, at one time, and you can look back in time 600 seconds (the amount of time kept on the waterfall display) to see what signals you missed while looking at something else. And this is a feature I use essentially every single time I set down at the radio.
Given the exact same situation, antenna and all, as you have asked, yes, I will hear more than you. The wider bandwidth display will allow me to catch short duration signals easier and more often, I do not have to be in the right place at the right time, I am everyplace at the right time. That is a fact. In fact, the problem becomes information overload, there is so much there that you have to skip some of it. Now, if I am just tuning to one frequency to listen to a scheduled broadcast this will not matter, but I almost never do that, and when I do I use one of the conventional radios, like the R-75 for example. The fact that the Excalibur can place three individual receivers in the DDC bandwidth means I can listen to or monitor, with one radio, three widely separated frequencies at one time. And the fact that the published numbers say the Excalibur is more sensitive and has a lower noise floor means that I can detect and use lower level signals.
I don’t know if you can justify the price increase for these rigs over something like the Softrock, only you can answer that. However I certainly can, and have.
Having used many radios and systems in the last 40+ years, including some of the best intercept and countermeasures gear Uncle Sugar could afford, I can easily see the value of radios like the R-75, the WinRadio Excalibur, the Microtelecom Perseus, and even the Softrocks. But I can also see the differences and the advantages of each.
Don't get me wrong here; I am not badmouthing the Softrock series at all. For the money they cannot be beat. Even for several times their cost they are excellent. But that does not mean that other radios are not better. Perhaps better is the wrong word, make that other radios can be more capable.
But, I will be ordering another Softrock kit as soon as I find a source with them in stock. The Ensemble II intrigues me, I can always use another low cost RX and really the only reason I did not keep my last SR was because of the limited tuning range. But, had I kept my SR I still would have gotten my other SDRs.
T!
Mohave Desert, California, USA
