I suggest checking out the QS1R receiver at:
http://qs1r.wikispaces.com
and you will be surprised to learn that the QS1R is the best Direct Digital Sampling SDR radio available.
The Perseus specs are also compared when you click on the link on the left margin.
And the QS1R sells for $100 less.
73, Tom Stanley N5YS
“you will be surprised to learn that the QS1R is the best Direct Digital Sampling SDR radio available” is quite a statement, especially with no qualification of cost or application on that statement.
I will say unequivocally that the QS1R is not the “best” DDC SDR today, there is no one thing it does that another SDR does not do better. Please note that I did not say it was bad, only that it is not “best” at everything. In fact I would say that no one SDR is “best” at everything, although some do some tasks better than others. I make that statement having used the QS1R and many of the other SDRs on the market, not based on the “unbiased” makers spec sheets or comparisons on the makers web site.
The QS1R is a better building block than many SDRs on the hobby market and is well suited to use in an amateur application where you might want a transmitter associated, possibly in this application it is the best sub $1000 SDR on the market. It might not, however, be a better building block than say an Atlas backplane and Mercury/Pennylane combination. It is also, definitely, not even in the same league as hardware like the Aeroflex 3030 series digitizers, but of course the Aeroflex’s are not “hobby” SDRs. You did not claim hobby SDR, you just said “best” SDR, that is pretty wide target there.
The QS1R has the widest basic frequency coverage (10 kHz to 62.5 MHz) of any of the current generation of hobby DDC SDRs (receiver only) on the market. But in the aliased mode several SDRs are wider. For example even the venerable SDR-14 will go to over 200 MHz. But if you want 6 meter DDC coverage with the best possible sensitivity in the hobby market than maybe the QS1R is the best compromise. I am not saying the QS1R is very sensitive, I am just saying that since it covers 6 meter native then it is the only DDC (no down converter or super heterodyne hybrid) on the hobby market that I know of. Of course, the Flexradio Flex-6700 also covers 6 meters and is DDC, and has far better performance numbers than the QS1R, but that is a transceiver, not just a receiver, and in a totally different price bracket.
The next thing the QS1R does “best” on the hobby market (receiver) is its ability to apply multiple individual RXs. It can apply up to 7 receivers on 7 different bands. There are several other pieces of hardware on the market that have the technical capability to do this, but only the QS1R is doing it as a regular thing using software an average user can come by. Of course again, the Flex-6700 can do 8 independent receivers, all at one time and with greater bandwidth each than the QS1R, but again the Flex-6700 is a transceiver.
After these two facts there is nothing the QS1R does “best”, even if we limit it to hobby receivers only, every other spec can be beaten by other hobby SDRs.
Want sensitivity? Most other SDRs on the market today blow the QS1R away. The QS1R has an MDS (500 Hz BW) of about -121 dBm (that number is from the QS1R spec sheet at
http://qs1r.wikispaces.com/QS1R+Specifications ). Even the relatively deaf SDR-IQ has -127 dBm (500 Hz BW). And things like the Perseus and Excalibur are often 10 dB, or more, better than the QS1R. The QS1R explains that away by claiming that “most” users are not in a quiet enough location to benefit from an MDS much lower than that, and that the Perseus sensitivity is wasted because the user so often has to select the Perseus attenuator “to avoid ADC clipping because of the Perseus excess gain” (direct quote form the QS1R web site). In a couple years of Perseus ownership (among other SDRs) I have had to use the Attenuator only a few times, and then most often when listening to one of my own transmitters. It could be said I live in a very quite location and I would not argue that, but I also access many remote Perseus SDRs via the Perseus network, often in urban installation sites, and also seldom have to use the attenuators on those remotes.
Want selectivity? Nope, the QS1R is not the top of the heap for that one either.
Want dynamic range? Unfortunately the test criteria (signal spacing used if multiple signal) is not defined on the QS1R web site, but the number, while very good if dual signal, is not the king of the hill. If the number shown is raw single signal dynamic range then the QS1R is kind of average.
Want maximum displayed bandwidth? The Excalibur and the Excalibur Pro can show up to 50 MHz of real time bandwidth. If you are talking about DDC recordable bandwidth then the Excalibur Pro can record up to 4 MHz of DDC window.
Further, in side-by-side tests I have tried the Perseus, the QS1R (no add-ons), and the SDR-IQ. On the same antenna, at the same time, under the same conditions, the Perseus consistently performed slightly better than the QS1R. The SDR-IQ generally did just as well as the QS1R on a single signal and at times slightly better, but naturally the SDR-IQ is not as capable an SDR as the QS1R in most ways.
So, as I have laid out above, the QS1R is not “best”. It is good, and I am not arguing against that. And it certainly has an application (core building block for amateur radio use) that is very good, even one of the best. But “best” is a difficult thing to say and stand behind.
If I had to pick a “best” hobby SDR on the market today, based on both performance numbers and having used many of the SDRs in question, I would have to say it would be the WinRadio Excalibur Pro, with the WinRadio Excalibur coming in second. I know several people who do not like the software (personally I think it is quite good) but no one I know who has actually used one can fault the hardware. On the other hand, if you have a transmitter and want to use the SDR as a display/receiver for ham use the Excalibur would be one of the furthest down my list, and the QS1R would be rather high on it.
T!