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

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  • Updated 3 years ago
  • (Edited)
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) ??
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Andrew O'Brien

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Posted 3 years ago

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Bob Craig, K8RC

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

http://www.sherweng.com/table.html
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Andrew O'Brien

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That table seems to produce basic performance data but does  not necessarily provide any information about SDR design differences. 
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km9r.mike

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the 6300's adc resolution / sampling rate is 16 bits / 122.88 Msps
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Walt - KZ1F

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And then you can take what Rob actually said. More hand wringing.
(Edited)
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KY6LA - Howard, Elmer

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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
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KY6LA - Howard, Elmer

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Since DynamicRange is a direct function of number of sampling bits, the 14 Bit ADC explains why any Flex has a better Dynamic Range
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Ken - NM9P

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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
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Lee, Elmer

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Official Response
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
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Bob - W7KWS -

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

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Bob I was trying to find the 6300's block diagram to look at that but I haven't been able to find it.  
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Bob - W7KWS -

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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.
(Edited)
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Lee, Elmer

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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
(Edited)
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Philip KA4KOE

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Has Bob Heil found his mind after losing it over the 7300?
:)
(Edited)
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butch alline

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What is this in reference to?  link?
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km9r.mike

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@ Phil

I saw a little of that and it was so over the top I could not even finish it.,
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DrTeeth

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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.
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Bill -VA3WTB

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Tim..what do you mean? all this hand writing as Walt would say is for nothing, what about all the testing that has been talked about,,,lol to funny
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Tim - W4TME, Customer Experience Manager

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Hand wringing, double blindness aside, we have de-risked the buying decision for those who are considering both the 6300 and the 7300. We would hate for someone to have buyer's remorse after choosing one radio over another.  It demonstrates we have confidence in our total SDR architecture and products.
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DrTeeth

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@Tim
"If you want to use both radios, buy a 6300 and 7300.  Use them for 30 days.  If you want to keep the 7300, we will refund you 100% of your purchase price.  You want to keep the 6300, we will refund you 90% of your invoice price of the 7300".
Be careful, you do not mention anything about having to give one of the radios back ;-).
(Edited)
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Ken ve7kwa

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<< If you want to use both radios, buy a 6300 and 7300.  Use them for 30 days.  If you want to keep the 7300, we will refund you 100% of your purchase price.  You want to keep the 6300, we will refund you 90% of your invoice price of the 7300. <<

Hmnn.. maybe some of the excess 7300's could be given away as contest prizes... First place gets a 7300 radio    Second place gets two 7300 radios... ;)     O.K.  O.K. people, it was a joke. I couldn't help myself... :)
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Ken ve7kwa

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<< If you want to use both radios, buy a 6300 and 7300.  Use them for 30 days.  If you want to keep the 7300, we will refund you 100% of your purchase price.  You want to keep the 6300, we will refund you 90% of your invoice price of the 7300. <<

Hmnn.. maybe some of the excess 7300's could be given away as contest prizes... First place gets a 7300 radio    Second place gets two 7300 radios... ;)     O.K.  O.K. people, it was a joke. I couldn't help myself... :)
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Barry N1EU

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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.
(Edited)
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Charles - K5UA

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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 slave a 7300 to a Flex 6500 so  that the 7300 would act as the transmitter, please let me know.
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DrTeeth

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Sometimes I think that there is too much adjustment possible with the Flex. And this long thread is just about qualitative audio quality :-o.
(Edited)
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Ken - NM9P

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@Mike....amen. Penetrating clarity will almost always win over over-compressed, overdriven "loudness."

I am amused when I hear, and see on my pan, stations getting frustrated in a pileup and beginning to eat the mike and shout, thinking that it gives them an edge. I can see that they are spreading their signal out, wasting power in Distortion products, and their shouting up close is reducing clarity....they now have two factors, each actually reducing their chances in the pileup....

If you want to play sometime, use the full duplex trick I used in my videos and monitor yourself in the second receiver . While you are talking, take the 1K slider and run it up and down slowly to both extremes and see how it affects your signal. It is amazing the difference power & punch vs. clarity and natural sound you will see. The trick is to find the balance between the extremes. The "perfect spot" along the dial depends upon your purpose.

The same goes for the other sliders, though the 500, 1K, and 2K are the most dramatic.
Too much 1k makes you sound "honky" or horn-like. Too little lack power and clarity.
Too much 500Hz makes you sound like you are in a barrel, Too little makes you sound weak, and vowels are Indistinct and hard to understand.
Too much 2K makes you sound sharp and irritating, too little and consonants become indistinct and clarity suffers greatly.
Too much 4K makes you "hissy" and sound like you have a lisp or a whistle when you talk. Too little and you lack high end presence. Even though 4K is outside the usual 2.9kHz filter bandwidth, the lower end of the enhancement curve overlaps some of the range covered by the 2K control.
Too much 250Hz makes you boomy. Too little makes you sound thin and lacking in low end presence.
The 125 and 63 sliders add foundation in rag chew or ESSB modes, and can be important in finishing out a quality profile.

The trick is to listen with a quality set of headphones while adjusting these controls one at a time through their respective ranges until you really become familiar with what they each add or subtract from your audio profile. As you listen, and look at the pan display, you begin to get a real feel for it. For your own voice, anyway......

I am afraid that I have gone far afield from the OT, but perhaps not. The ability to adjust proper transmit profiles is a major part of the SDR functions of any modern rig.

Good luck, and have fun.

Ken - NM9P
(Edited)
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Walt - KZ1F

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So Tim chimed in with Flex's try it for free for 30 days against the 7300, buy both. I concur with Rudy's assessment on that, but hey.

No, I am not advocating people buy an ICOM or Kenwood or anything else. To distil this out for people is to use good arguments to make your case, not contrived ones that reflect poorly on the people that use them. How one markets a product, any product, counts, even if it's done by amateurs.

I own and use a 6500. There are many things I like about it. There are some I do not like about it. Some of those I've resolved. Requiring a computer to simply read the mail, I haven't and not sure I can but I did make a heart-felt suggestion about a product I felt will have tremendous traction, if only, with the non-contesters in the population of Amateur Radio Enthusiasts. I agree with Barry, someone is going to do that. I prefer it be Flex as I've made a rather large investment in SSDR.

If this is sounding like I am kinda wrapping up here, it is, as I am.
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km9r.mike

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@ Charles

Hi Charles. Just a quick follow up to back up your praise for the tx audio of the 7300. Please keep in mind that I have not had the rig on for the past 20 days due to work sched so I have not had the opportunity to hear yet what you have heard. I only had the opportunity to hear an early tester and an early user and they could of both had improper settings. Regardless, I initially did not hear anything remarkable.

 I was listening to some ssb this evening and heard two 7300's out of a total of four that had  imho audio that was probably in the top 10% of the best audio that I have heard before on the bands.  Both were using amps and both were no more than 100 mi away so signal strength was not an issue. Of the two one said he was just using the supplied hand mic and for a stock radio (plus amp) and it's supplied hand mike... wow. Easy better than average and like you previously noted borderline high fidelity and that was for the ( for lack of better terms) contest mode setting. It would easily be a signal that would stand out in a crowd in a good way.

The other op was in rag chew mode I presume. I did not hear what his audio chain was but I know it included a 7300 and that was rich, clear, good low end and borderline high fidelity as well. What was very noticeable as well for both was a very clean sounding audio. Just the op's voice with a dead silence for the background.

The other two 7300 were low in signal strength and were both at 100w. Their audio was not poor but it did not stand out in a good way either. BTW I have heard very clean very clear audio from radios who's signal strength were almost  at the noise floor and I am sure you have as well but those two examples were not like that. I am not certain why.

For the two stronger signals, just like you said very impressive and there is no doubt in my mind you have a far better understanding than I of what it takes to make that happen. Plus it sounds as if you may hang out now and then with the essb gurus which I have zero experience with.
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km9r.mike

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@ Ken

Yes sir and thank you for the additional help. In my previous post I was gonna point out that I have not attempted your full duplex technique yet but it is on the to do list. I tried listening on a separate receiver but I was not hearing finer adjustments so I concentrated on your panfall tips and received two very positive reports for two completely different settings 1. rag and 2. dx/contest . I was very pleased with the reports because in a way I was making settings w/o having any idea of how they actually sounded. I could only see the results, but following your advice I received two positive reviews. I will now try to fine tune both ( where applicable) with your full duplex technique and eq pointers.

Finally, I have never thought about it that way but indeed any distortion or excessive width outside of the tx bandwidth is simply wasted energy.
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W7NGA

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Methinks if residual FM, phase noise, modulation index, and ultimate dynamic range is your main concern and focus in Ham Radio .. then sorry, you've missed the salient point (in my opinion) of being an amateur radio operator. Just to be clear .. I've seen more heart and soul in the guy with a DX60 and Hallicrafters SX101 .. trying to talk to his brother in Namiba on CW, than any of these soulless discussions of Sherwood rankings and the thrill of working Africa whilst sitting on the deck sipping a cool one with a Maestro in their lap, remote. Reality check ... just what do you want from amateur radio? At the end of the day .. what do you come away with that has enhanced your life experience in some positive way and afforded you a glimpse into the life of someone around the world? That's ham radio (for me) .. this thread, just noise. Sorry to be blunt. But I feel my 50 year obsession with this hobby slowly slipping away into the noise per discussions like this one  .. insipid, vacuous, sometimes inane.

I spent my weekend listening with my 6500, trying to find these stations in dire need of uber-clarity, 16-bit dynamic range, on the bleeding razors edge of competition and remote performance demands vis-a-vis Maestro and the ultimate Bluetooth connection .. and all I heard was San Diego, California, 599, TU. Next? That's ham radio? I did hear a SSB station on 17-meters from his hot tub ... with Maestro and a Martini in tow. S9+, California, QRZ? Geez ... 

W7NGA  dan
San Juan Island, Wa.
(Edited)
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k3Tim

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Was it the Martini that threw you off? 
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W7NGA

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Absolutely .. 17-meters deserves a fine French Bordeaux.  
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Ken - NM9P

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Dan. Who said that just because this is the current topic of discussion in THIS thread that it is anyone's main concern or focus in the hobby?

I am currently engaged in several concurrent conversations in this and other forums, some public, others private. None of them represent anything lose to an "ultimate concern" in my life. But they are, at least, temporarily interesting. Many of them are done while multitasking in my office or at home in my easy chair while watching tv or waiting for dinner. A few of them I only post to when I am in the "reading room" because it gives me something to do....

Sometimes sports car enthusiasts want to talk about cubic inch displacement, compression ratios, fuel mixtures, horsepower and transmission efficiency..... Sometimes they just want to drive their cars!

The same goes for amateur radio nuts. The fact that we sometimes spend time doing one thing doesn't mean we do not like to, or are incapable of doing the other.

Cheers!

Ken - NM9P
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Ken

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Dan,

I think there are more out here that think exactly like you do, but don't bother to say anything. I think it's called the "silent majority"...

Ken - W3KWL

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km9r.mike

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@ Dan

I hear your passion but one's passion does not make another's invalid, insipid, vacuous nor inane. What's next ? Are you gonna call others nerds ?

It is a big hobby with lots of room for lots of passions. I could easily take a swipe at your passions but it would not make me a better man.
(Edited)
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Lewis Cheek

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Dan, ur 599 plus about 40 on my xyz, antenna is  7 phased 5 elem 20 meter beams, on one of my 12, 350 ft towers. By the way, I'm on my 500 foot daysailer over in the Mediterranean Sea running remote via a Maestro. Wait a minute please I need to ask our house setter to drive over to my remote ham shack and fire up the other 10 kw amp, and parallel it with one I'm running now. Waiter when will the $5000 bottle of wine arrive?

Seems I read a lot of that kind of stuff on a few reflectors. :)

Lew - N4CO