I'll try to keep this short. First, the review I quoted was the first one the ARRL, I went back and read the second one. Some comments:
I agree the numbers that came out of the test are impressive. Very impressive. Your SDR-1000 receiver is better than the Icom 7800. Good luck, with a receiver like this you should be making millions of dollars selling it in the commercial market. Now a little of my engineering scepticism. The numbers are sooo good for some of the things like the third order intercept SDR-1000 +15 dB vs Icom 7800 of +0.5 dB that I have to wonder if the measurement techniques are applicable between the two totally different types of radios. It wouldn't be the first time I have seen this. The Icom is a commercially accepted high performance receiver. Now yours may be vastly superior to the 7800, but please forgive my scepticism. Again, if it is, you are in line to make a fortune! I understand your promotion of your products. But again, if I understand what your promoting, forgive me if I have doubts that an $85,000 system is comparable to what you say may cost less than $300. In my soon to be 56 years on this earth, I have learned that you get what you pay for and seldom, if ever, get a deal like this. If you can offer one at that price, again, congratulation, you are going to be the next Bill Gates! You might also be up front and tell the folks on an HF Digital forum, that as of the last ARRL review the turn around times of your system makes it usable for ARQ modes at the least. Like 170 ms versus 24 ms for the Icom ProIII. Likewise that the group delay of the software filters requires reducing the number of taps from around 2000 to 200+, thereby reducing their effectivness for digital communications. You might mentionthe ARRL tests showed the SSB carrier suppression and opposite SSB suppression on TX is only 53 dB vs the ProIII's at >70 dB. Again, over my lifetime, I have learned that not everything comes up roses. Products require compromises and you need to be up front with the pimples. Lastly, you said "...it is frustrating to me personally that what is happening right under amateur radio's nose is so badly misunderstood and insufficiently appreciate. I believe as strongly as I believe I am typing this note that most of you have purchased your last conventional HF transceiver because of this work. What vehicle should I use to scream these roof tops so educated interested people like Jim can understand how much things are changing?" I do understand how things are changing, but I also understand how they are not changing. A little background. I am a BSEE, and when I started work at Southwestern Bell Tele. (now AT&T) I was like you and couldn't believe how backward folks were. How computers should be changing the world RIGHT NOW. However, I learned there were budgets, for hardware, software, and most importantly, hiring and training people. These budgets were limited and controlled how fast things changed. Now some marketing/product advice. Ham radio isn't much different from what I learned in business. Most hams are doctors, lawyers, truck drivers, farmers, etc. They are not computer hardware/software engineers and want these things to work out of the box with simple cables to hook up. They want the red connectors on the cable to hook up to the red connectors on the computer/external box. Same wiht the blue and green ones. Drivers to worry about, forget it! To upgrade software, hit a button and the process is automated - entirely, start to finish. The biggest impediment you have is ergonomics. I suspect a lot of hams are like me. I want to take my Icom 745 to the RV, hook it up 12 volts and the antenna and use it. Very little space and a simple handle to carry it with. Remember this is a hobby, I am lucky I have two radios, a lot of folks don't nor can they afford it. That means your radio would be the only one they have. How portable is it? Not very! You want to multiply sales. Integrate it all, screen included. Make it absolutely as small as possible, i.e. portable with a handle. Make it run entirely off of 12 volts. Forget hard drives, find as small as OS as possible and use a flash drive that can be exchanged for upgrades. Make every file read only. Let the experimenters/devlopers that know how use a regular computer and make the files writable. You have a decent product but so was the Edsel, betamax vcr, etc. You have to find out how to make people want it, not bemoan the fact that you built it but they won't come! Jim WA0LYK --- In [email protected], Robert McGwier <[EMAIL PROTECTED]> wrote: > > jgorman01 wrote: > > S-meters are not just logarithmic indicators, they also indicate the > > gain reduction being applied in the RF/IF chain. As I said in a > > previous post, it is an indicator of the reduction in gain, i.e. how > > much of an attenuator is being inserted. By inserting this attenuator > > you are not just inserting an S5 level of reduction, but an S9+10 dB > > level of attenuation. Therefore the smaller signal is reduced by a > > much larger amount than its absolute level would need. This means it > > doesn't come out of the audio amp at an S5 level but at something much > > less. > > > > SDR's still have to deal with the real analog world at some point. RF > > preamps and amplifiers that have a large dynamic range are not easy to > > design and build. That is why AGC is applied to them, to limit the > > range they have to handle. As an experiment turn off your AGC and see > > what level of signal it takes to overload at least some of the stages > > in your receiver. I can HEAR audible distortion on S9 signals. This > > means signals much less than this also have distortion. Now this may > > not be occuring in the first RF stages but it likely could be. > > > > This is wrong. > > The SDR-1000 has a measured IMD-DR over 100 dB, with an IP3 north of 30 > dBm. It does not have a single analog amplifier with agc on it. All > agc is done strictly in software. Great use is made of the fact that > 200 kHz wide I/Q if's may be captured using modern audio codecs that > exhibit 99 dB of dynamic range themselves (or more) and then we proceed > to filter and downsample and get increased range by doing that. This of > course limits the blocking dynamic range to about 100 dB as well. This > will increase as a DIRECT result of getting and using better codecs. > This is happening now in support of the SDR-1000 by HPSDR. > > > > SDR's may very well be an answer to cheaper high performance > > receivers, but so far the measurements I have seen don't show a > > dramatic improvement, for example, even half again the dynamic range > > of current decent analog receivers. See the ARRL review on the > > SDR1000. I am sure better performance will come, but at what price is > > a question. Here is a reference I found about a high performance system. > > > The SDR-1000, with which I am intimately familiar (having jointly > written all of the DSP software in it with AB2KT) was a stack of boards > layed out with a free tool. The stack of boards are 3x4 inches because > that is what Eagle would do for FREE. It is a "beyond lucky" > happenstance that with small component modifications the thing is able > to get the numbers mentioned in the ARRL review. I suggest that you > have misread it if you do not understand what a complete REVOLUTION the > SDR-1000 is. The high dynamic range and the IP3 measured in the ARRL > review ARE AT 2 KHZ! Not 20 kHz, not 5 kHz but 2 kHz. And the only > reason the measurements are not done closer than that is the ARRL > laboratory is incapable of have a sufficiently noise free generator to > measure that close. > > The ARRL review you quote states (AFTER the review for the Orion and > IC-7800 came out) that is was about the best receiver ever measured in > the ARRL labs. > > MAJOR technical innovations have been made inside and outside of Flex > Radio on the theory and implementation of the what Gerald calls the QSD > and what others call the Tayloe detector. I understand its principles > of operation completely having completed a detailed transform analysis > and have suggested how to greatly improve the circuit. These > considerations are being applied by Gerald in his new receiver design > and they are being applied by HPSDR in a separate design based on low > noise amplifiers I chose and a codec I recommended and an approach that > started with Phil Covington, N8VB and spurred my technical analysis > after Tayloe said that the essential nature of the beast was an > integrator and not an RC network. > > I do believe people will be shocked at how unbelievably capable these > inexpensive receiver components will be. For Flex Radio, they will be > applied in expensive radio systems under design for the high end user. > In HPSDR, they will be applied in modules clearly aimed at the > experiment. We have, absolutely no doubt in my mind, the CORRECT > tools to do amazing digital work for HF and reasonably inexpensively > should we choose or very expensively if we choose to have a major new rig. > > > > "The Model 7640's FPGA serves as its control and status engine, and is > > supported by 512MB of DDR SDRAM for buffering functions, such as data > > capture and delay. The transceiver digitizes HF (high frequency) or IF > > (intermediate frequency) input signals using a pair of 14-bit, 105 MHz > > A/D converters, and generates output signals with two 16-bit, 500 MHz > > D/A converters." See it at > > http://www.linuxdevices.com/news/NS3911104852.html > > > > It only retails for $85,000! > > > The HPSDR Mercury and Ozy boards are 135 MHz 16 bit A/D with > 90 dB > range (I measured the A/D) and two Cyclone II FPGA's cascaded. After > you do digital down converters in the FPGA's, we will have in excess of > 100 dB of dynamic range (processing gain) which we can aid with the > blocking dynamic range (near/far A/D issue) with ham band filtering. > > I am going to GUESS at the total cost for this. THIS IS AN EDUCATED > GUESS AND TAPR WILL NOT BE HELD RESPONSIBLE OR LIABLE FOR MY GUESS. > > These boards plug into a backplane designed for the HPSDR project. $40 > kit for the Atlas backplane. > > Mercury is a high speed A/D and FPGA and I am going to GUESS that it > will sold, wired and tested for UNDER $300.00. It plugs unto the > Atlas backplane. THIS IS A GUESS. > > Ozymandias is a USB interface and bus master board with another Cyclone > II FPGA. Thus we have cascaded FPGA's in this system before entering > into the USB port to deliver to the remainder of computation and display > and GUI. A lot can be done with this system. I can process all of 20 > meters, tell you who us USB, RTTY, CW, PSK31 and do a "PSK31 deluxe" > style demodulator on the stronger signals (the digital, not the voice). > I GUESS that it will be sold, wire and tested, for UNDER $300.00 > > There is a modified QSD, of the type I mentioned above, being developed > into another plug in board. It will ultimately have in my opinion, > >110 dB dynamic range, IP3 north of 40 dBm and it will use the same > codec as the thousand dollar sound cards we lifted the idea from (the > Akashi AKM 5394A) and this will be laid down in a completely balanced > current mode I/Q mixer/IF filter to mix to nearly baseband for software > processing. > > Jim > > WA0LYK > > > > > > In my capacity as chairman of the ARRL SDR Working Group, Flex Radio > software designer and technical bottle washer (unpaid volunteer), my > HPSDR contributor status, AMSAT VP Engineering and TAPR member and > supporter, it is frustrating to me personally that what is happening > right under amateur radio's nose is so badly misunderstood and > insufficiently appreciate. I believe as strongly as I believe I am > typing this note that most of you have purchased your last conventional > HF transceiver because of this work. What vehicle should I use to > scream these roof tops so educated interested people like Jim can > understand how much things are changing? > > 73's > Bob > N4HY > > -- > AMSAT Director and VP Engineering. Member: ARRL, AMSAT-DL, > TAPR, Packrats, NJQRP, QRP ARCI, QCWA, FRC. ARRL SDR WG Chair > "You see, wire telegraph is a kind of a very, very long cat. > You pull his tail in New York and his head is meowing in Los > Angeles. Do you understand this? And radio operates exactly > the same way: you send signals here, they receive them there. > The only difference is that there is no cat." - Einstein > Need a Digital mode QSO? Connect to Telnet://cluster.dynalias.org Other areas of interest: The MixW Reflector : http://groups.yahoo.com/group/themixwgroup/ DigiPol: http://groups.yahoo.com/group/Digipol (band plan policy discussion) Yahoo! 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