The "SDR" part of the Icom 7300 compared with Flex ?

Andrew O'Brien

I read the previous threads about an Icom 7300 verus Flex Signature series radios.  Most of the comments were subjective comments and some views on the ergonomics of the Icom. From a SDR design perspective (not knobs/lack of knobs, USB control, etc) how is the Icom compared to the technical specifications of a Flex 6000   (ADC sampling, etc) ??

Bob K8RC

Well, you can start with the objective test results at Sherwood Engineering:

http://www.sherweng.com/table.html

km9r.mike

the 6300's adc resolution / sampling rate is 16 bits / 122.88 Msps

Walt - KZ1F

And then you can take what Rob actually said. More hand wringing.

Andrew O'Brien

That table seems to produce basic performance data but does  not necessarily provide any information about SDR design differences. 

KY6LA_Howard

ADC: Linear Technology LTC2208-14. ADC driver: Linear Technology LTC6401. FPGA: Altera EP4CE55F2317N. DSP: TI TMS320C6745 (375-456 MHz, low power consumption). DAC: Intersil ISL5857IAZ. ADC sampling rate: 124.033 megasamples/sec

KY6LA_Howard

Since DynamicRange is a direct function of number of sampling bits, the 14 Bit ADC explains why any Flex has a better Dynamic Range

Ken - NM9P

7300 vs flex... 14 bit ADC vs. 16 bit ADC - dynamic range and blocking dynamic range will be a little lower. I have not seen any figures about phase noise in the oscillator for receiver or transmitter on the 7300. This will be potentially more important than many other parameters because it will determine real performance I. The presence of strong close signals. It will also determine how much it interferes with other nearby rigs. The flex 6000 series phase noise performance is superb. Implementation of shape factor on SSB and CW filters ... Skirts are much sharper on the flex. But using wider skirts allows the Icom to have a lower latency number. Flex currently gets the edge on selectivity. But this is software and can be changed by either manufacturer. The flex 6000 series allows 2/4/8 channels of simultaneous digital (DAX) audio output to digi programs. I don't know how many the 7300 is capable of. These and other characteristics will help inform a comparison. Of course they are in different performance categories, but both are nice rigs. Ken - NM9P

W9OY

I believe the 7300 is more like a SDR-1000 in terms of its design.  It direct converts to a baseband through the FPGA which then feeds a 36khz signal into a DSP chip where the "SDR" magic happens.  I think the chip is a version of Icom's off the shelf chip they have used since the Pro-3.  In the down conversion some video is split off from the FPGA and sent to a cell phone size touch display display.  The display has a maximum range of 1mhz or possibly 2mhz (the specs I read were not exactly clear)  The radio has 15 band pass filters so it is very different from the Flex.  IMHO all those filters were Icom's attempt to clean up ADC overload.  This design necessarily limits how much the "software" can be modified compared to the 6300 but the DSP is already pretty mature so I don't expect much modification to be happening anyway.  I don't think the FPGA has very much horsepower either.  

The 6300 picks up 7mhz of spectrum with it's more robust ADC and that is what is processed which is why you can view 7 mhz of bandwidth, and does not rely on any kind of BPF to pre-select the RF.  It's a very different kind of architecture with a more powerful ADC and FPGA as well as internal control processors which is why it can be a server and have he Flex API's etc.  The video is considerably superior in the information it conveys.  Like the 7300 the radio is primarily controlled through the display.  The 6300 is a considerably more complex and Flexible transceiver given the fact that it serves DAX and CAT as well as being able to connect to and tightly integrate with a multitude of third party programs.  For me the difference is like the difference between playing checkers and 3-D chess. 

73  W9OY

Bob - W7KWS -

Lee, How do you describe the Flex 6xxx FPGA & audio recovery arcitecture?

W9OY

Bob I was trying to find the 6300's block diagram to look at that but I haven't been able to find it.  

Bob - W7KWS -

Lee,

It seems to me that comparing the 100% digital receiver of the Icom 7300 to the largely analog, digital-hybrid design of the SDR-1000, is somewhat misleading.  Or am I mistaking?

Like you, I don't have the benefit of a Flex 6xxx block diagram at hand but, for the receiver audio chain, I'll bet that the Flex and Icom differ very little in basic architecture.  Surly the Flex features higher end parts but I'll bet this extra horse power in the Flex is devoted mostly to its superb, extremely wide frequency video display and the other higher end features such as DAX, client/server, Etc.

W9OY

I didn't say it was a SDR-1000.  Actually the KX3 has even more SDR-1000 character.  My point was the 7300 down converts to baseband "audio" before sending the down converted "audio" to a DSP chip for processing.   This architecture therefore was an obvious bow maximizing  cost containment rater than performance.  Cheap ADC, cheap FPGA, cheap screen, cheap DSP.  The architecture therefore limits the performance.  You can drop in a 16 bit ADC (there actually is a drop in 16bit version of the ADC used in the 7300, which is why I believe Icom cheaped out in its design) and use the same architecture and the performance of the radio will still be limited.  This is why a "next version" while for sure having more features will still be down the performance curve.  I don't recall the 6300 having any sort of DSP chip as a bottleneck.  As I recall the Flex takes full advantage of the versatility speed and bandwidth of the FPGA.

The OP asked about the difference that's the difference.

73  W9OY

Philip KA4KOE

Has Bob Heil found his mind after losing it over the 7300?

DrTeeth

Coming from a medical background, rather than tech specs or design perspectives, one needs to have "double-blind" trials of rigs. It would be quite easy to set up so one would get real world results.

Barry N1EU

I'm no DSP engineer, but the IC7300 directly samples RF down to a 36KHz baseband as opposed to the 0KHz baseband of Flex and they did this to allow them to use their existing dsp library.  Why is using a 36KHz baseband in and of itself an inherently inferior architecture?  

The one outstanding question about the IC7300 in my mind is the whole OVF, IP+, RF Gain implementation.

butch alline

What is this in reference to?  link?

butch alline

++ double blind.  ++ real world.

One can compare specs on a Ferrari, Bently, Porsche, and Chevy Volt and still not come up with a clear cut choice.  You have to drive one, look in your wallet and then decide which one is for YOU.

 

Bill -VA3WTB

But based on the specs and build of the Bently, I would think the Bently would be a nicer car to drive then the Shevy. And much higher performance. Without driving them...

DrTeeth

Butch,

In my experience, one has to live with something before one can make a judgement. No matter how long one tries something out for, it is often not long enough. Yes, in that I also include XYLs! Nobody gets married without any other expectation that it will be for life - nearly 20 years and counting at this QTH.


Steve K9ZW

Consumer preference testing more often requires full product exposure. The use of the double-blind methodology seems less useful or common. As for vehicles a lot depends on how you use them. As I trade at 75-90,000 miles my personal driver gets swapped every two-three years. Strictly a financial set of calculations. "Fun cars" and motorcycles I turn over much slower. Radios even slower yet. Some I never sell. 73 Steve K9ZW

Walt - KZ1F

Where the analogy to marriage breaks down is people continually change so the person you dated in highschool won't be the same person 10 yrs later. That radio will be, for all intents and purposes.
The whole dbl blind thing is simply college psychology and statistics. People have preconceived notions of what they like and prefer yet the results show, often times, is they act prefer something else entirely.

An interesting example of this is where my wife and I used to vacation in Jamaica. One of the games they play as they take newlywed husbands and wives and blindfold the husbands and the husband would have to pick out their wife by virtue of how their kiss was and it was amazing sad and funny how many got it wrong. That wasn't an example of double blind but I thought it was funny and kind of pertinent to this issue. And no, my wife and I didn't play those reindeer games.

DrTeeth

@Walt
"The whole dbl blind thing is simply college psychology and statistics."

It is far more than that Walt. It rules out personal bias in the testing methodology (on both sides), which it is why it is used in the medical field.
Look at all those who say that Advil is really great but Ibuprofen never works for them. To save you looking them up, they are both the same thing, and exactly so.

It also deals with those non-scientific people who see a cause and effect when non exist. You know, the people who will not consider 'coincidence' when they think that some junk science garbage has 'worked' for them.

@ Steve
"Consumer preference testing more often requires full product exposure. The use of the double-blind methodology seems less useful or common".

When comparing the ride of a vehicle, a Ford fan will tend to prefer the rid of a Ford over a make that is disliked, whereby blindfolded, the reverse may be true. There is a LOT of unavoidable bias with full disclosure even though a double-blind test may not be practical.

Bill -VA3WTB

How can you have a blind test? It would take hours to put both radios through all possible operating conditions.

DrTeeth

Bill,

All possible operative conditions would not be required, just a broad enough example. It would certainly be much more valuable than the 'on-air' tests one sees in the ham mags

It would be MUCH more useful, even in a limited form, than reading the tech specs. 'Hours' is a small price to pay for such quantitative information.

As to how? One sends a library of inputs to a rig under various standardised 'propogation conditions' and there are hams listening to the outputs and the decide which they prefer and why. The listeners do not know the rigs under test and heither do the people having contact with the hams. The chat in the lab driving the rigs only communicates via lights, "ready?", "place headphones" etc.

I am sure I could do much better if I thought about the 'problem' for longer than I did to produce the above.

Charles - K5UA

Hi Barry,

Before the criticism starts over what I am about to write, let me state that I am very satisfied with my Flex 6500 and I think the Flex software engineers are going to really impress us in the next year or so.

Now to the point.  In all of the Icom 7300 vs. Flex 6000 series discussions I have read, I don't recall anyone mentioning how absolutely fantastic the 7300 transmit audio sounds. 

I have been involved with "hi-fi" ESSB audio ever since W2ONV started experimenting with the Focusrite Red series mic preamps in the 1990s.  I must admit I have never heard audio more open and pristine than the audio I have heard from the 15 or so 7300s I have heard on the air.  I have heard lots of wonderful ESSB audio over the years, but I am stunned by the transparency, fidelity, and lack of coloration of the audio coming out of these 7300s at a mere 2900hz bandwidth.

My point is this.....the 7300 may not hold a candle to the Flex 6000 series in every other aspect of radio performance, but the transmit audio is superb.  I am not saying that the Flex audio is not up to par, but there is nothing that I have ever heard, at any price point, that can compare with the transmit audio of the 7300.  My opinion, and my opinion only.  If anyone knows a way to **** a 7300 to a Flex 6500 so  that the 7300 would act as the transmitter, please let me know.

Walt - KZ1F

Sorry guy, I wasn't clear. NO, dbl blind testing is definitely more than college psych and stat. I said that as unless one took those particular subjects it would seem as garbledy ****. No, it is extremely important.

Bill, I believe I will be concurring with Guy on this but the test can be very straight forward. Forget the lab gear testing, which radio sounds better to the listener, not volume, clarity of signal, be it a distant weak signal or a complex high fidelity AM or ESSB. As an example I threw in the real life example. How many people would admit they couldn't differentiate their spouse from a woman they never met? Yet, may can't... in fact, based on that sample, most can't. It might well be random guess work. And that is where the statistics come in to see if a random correct guess or even incorrect guess is telling. My hypothesis is within the top 10-20 in the sherweng list, in fact based on the audible signal, one can't tell the difference between any two. On pre-knowledge a subject will choose that which is whatever they are predisposed to want, like picking their wife vs a complete stranger.

DrTeeth

Got it now Walt.

Bill -VA3WTB

Yes i see your point, but considering radios may have better performance on a condition vs another condition. Such as a crowded band with big signals, or a condition with very weak signals.

Steve K9ZW

In the consumer world Double Blind tests are disconnected from market acceptance.

You can through elaborate DB Testing do some qualitative comparison and a limited amount of subjected end user comparison, but all goes out the window when the branding and distinguishing product characteristics are unmasked.

 With ethical modifications DB Testing is of great use to separate pure performance from other biases in areas like the medical field, but ill applied in market acceptance studies.

Please remember that a great many of the radios out there have arrived at product development levels that "to the ear" are not readily different - they all exceed our limitations as testers. 

So it is the subject qualities - packaging, ease of use, displays, knobs-vs-no-knobs, remotability, price-point, brand-perception, ownership-emotives, product features, specific task features, and much more measures of difference, that are what we really make our purchase decision on.

DB Testing is an ineffective, inefficient and useless undertaking in comparing one consumer product to another in terms of total product packages.

If you only have a hammer, not everything is a nail.  There are more appropriate tools than the "hammer" of Double-Blind Testing to do product comparisons.

73

Steve K9ZW

DrTeeth

@ Bill.

Those scenarios can be simulated and don't forget, you only have a list of tech specs at the moment to look at.

@ Steve

I am not suggesting that DB testing will supplant any other test nor should be the only thing considered when considering a purchase. Also, I am taking about testing and not the whole gamut of a purchase decision process.

Other than that, I would just like to say, politely, but strongly, that I disagree with your take on DB testing. Without breaking into a sweat, I can think of many things that DB testing will bring to the table where there is nothing at the moment.