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Author Topic: KX3 SDR  (Read 44845 times)
KE5JPP
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« Reply #60 on: November 16, 2012, 05:12:31 AM »


So, does anyone know if the KX3 I/Q lines can be used at 192khz as well or are they limited to only 48, or 96khz wide?


I read that it could on page 26 of the KX3 user manual if fed into a 192khz sound card.  I am interested in buying a KX3 to use as an SDR rig, but have not read of anyone who has actually done this yet.  The manual is terse on this, and the forums provide little additional feedback on this thus far.   

I wonder if the optional 'roofing filters' is added to the KX3 if that effects the I/Q output bandwidth?

Gene
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KE5JPP
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« Reply #61 on: November 16, 2012, 07:11:07 AM »

According to the information I could find doing a search, it appears that 192 kHz is possible.  Still don't know what happens with the optional I/Q roofing filters as far as bandwidth.

Gene
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NI0Z
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« Reply #62 on: November 17, 2012, 07:06:07 PM »

Most of what you are looking for is in this article here including screen shots.

http://roaringstar.com/index.php/articles/66-kx3-nap3-lp-brige-dm780-setup

Hope this helps!
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KB1YOO
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« Reply #63 on: December 19, 2012, 12:33:34 PM »

What happened to this thread?.. It was getting really interesting and then everybody ran out of gas. I just bought an SDR IQ and a KX3 and interface to an iPad using iSDR. Hey NI0Z your photographs are really incredible.
You also have the right perspective in your outlook. As a new ham you are Asking the right questions. As for myself, I got licensed at 13 in 1953 and the let my license lapse when i worked overseas. I finally got relicensed recently so i am looking at things from your point of view.  Don't let the arrogant engineers deter your initiative. I have run into these guys before and they think the world revolves around them instead of an actual product. Don't get me wrong, these guys are good at what they do but are never in charge of reality. There are some guys who think you don't know how to program unless you use UNIX with a Black and white text terminal.  Hi hi

So relative to your link on the KX3 bandwidth, I keep experiencing inconsistencies. From what I read, I believe the maximum possible KX3 IQ bandwidth display is 192kHz with a sample rate of 192kHz. The KX3 manual states this rather obtusely. I have to say that I have never seen any of the popular SDR programs show a KX3 bandwidth spectrum of 192kHz. I cannot get it to work either.  Maybe it's me.

Regards, WK1K previously KB1YOO
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NI0Z
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« Reply #64 on: December 19, 2012, 07:37:40 PM »

What happened to this thread?.. It was getting really interesting and then everybody ran out of gas.

So relative to your link on the KX3 bandwidth, I keep experiencing inconsistencies. From what I read, I believe the maximum possible KX3 IQ bandwidth display is 192kHz with a sample rate of 192kHz. The KX3 manual states this rather obtusely. I have to say that I have never seen any of the popular SDR programs show a KX3 bandwidth spectrum of 192kHz. I cannot get it to work either.  Maybe it's me.

Regards, WK1K previously KB1YOO

Lol, not out of gas, just really short on time these days.  Thanks for the nice comments.  Just as I try to understand long timer perspective I agree you can learn lots from short timers.  We newbies see everything through rosé colored glasses when it come to the hobby and there is so much that is new and exciting with ham radio.

You won't get more than 96K.  To get 96K you set the sampling rate to 192K.  IE you get half the set sampling rate.

As compared to many new SDRs this is rather limited.  It's still very usable.

What I find when people contact me most times with inconsistency is two things.

Failure to use an isolator like the one from radio shack or something better.
Use of NAP3 which in the version I last used has a bug where things can shift after you switch to CW and back.

While the article I provided isn't perfect, if followed carefully offers enough to get it all working.  Might have to read it a few times, but it's in there.

I am thinking that 2013 is going to bring us some cool stuff!

Have fun!
NI0Z
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KB1YOO
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« Reply #65 on: December 21, 2012, 10:35:09 AM »

OK Somehow I have stumbled into the truth! Bottom line is (happily) the KX3 DOES do 196kHz bandwidth and I finally got it to work.  Remember that there are TWO IQ audio lines to sample at 192k each, which give you a BW of 96k each side of center .. sum total BW = 192k. So you set your sound card to stereo line in sampled at 192k. And then use your favorite program and it should display properly.

Here's what I did specifically..
.. used an old 2008 MacBook laptop dual boot running Windows 7 standalone.
.. configured sound card for stereo line in 16 bit 192k sample rate.
.. ran KX3 RX I/Q cable direct into stereo line in
...40 meters was pretty active so I tuned the KX3 to 7200 kHz
.. ran SDR-RADIO app
.. before hitting the start button, set up the BW display (right click) in the app for 200kHz
and set input for the Soundcard option then select line in as device @ 192k sample rate
… also INVERT the IQ
.. click the Start button
.. the waterfall will start and always be centered at the current KX3 frequency
. .if you tune the KX3 up in freq, the waterfall should shift left
.. The waterfall display will show funny frequencies on the bottom..ignore them and don't mess with the ham band buttons or you will lose the waterfall.

Then I started up another copy of SDR-RADIO and attached to my local SDR-IQ. I also connected to the same antenna. I centered the SDR-IQ freq to same as KX3 and voila! Both waterfalls pretty much matched. It looked like there was a spurious signal reflected off center at +- 40 kHz. It didn't move when I tuned freq. Probably need to use the I/Q balancing utility in SDR-RADIO.

I also ran the HDSDR app with KX3 input and got the same bandwidth pattern results..

Then I plugged the KX3 IQ into the iMic and connected to the USB on my laptop. I couldn't get more than 48kHz bandwidth. I am using the iMic on my iPad so it is good enough for now.

So if your laptop sound card can do 192k stereo per channel sample rate, you are probably good to go. Otherwise just buy one of the high performance USB sound cards (but NOT iMic).

So have fun.. now I am starting to think my SRD-IQ is redundant.

DJ - WK1K previously KB1YOO previously W8PID
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KE5JPP
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« Reply #66 on: December 21, 2012, 01:50:57 PM »

OK Somehow I have stumbled into the truth! Bottom line is (happily) the KX3 DOES do 196kHz bandwidth and I finally got it to work.  Remember that there are TWO IQ audio lines to sample at 192k each, which give you a BW of 96k each side of center .. sum total BW = 192k. So you set your sound card to stereo line in sampled at 192k. And then use your favorite program and it should display properly.

Here's what I did specifically..
.. used an old 2008 MacBook laptop dual boot running Windows 7 standalone.
.. configured sound card for stereo line in 16 bit 192k sample rate.
.. ran KX3 RX I/Q cable direct into stereo line in
...40 meters was pretty active so I tuned the KX3 to 7200 kHz
.. ran SDR-RADIO app
.. before hitting the start button, set up the BW display (right click) in the app for 200kHz
and set input for the Soundcard option then select line in as device @ 192k sample rate
… also INVERT the IQ
.. click the Start button
.. the waterfall will start and always be centered at the current KX3 frequency
. .if you tune the KX3 up in freq, the waterfall should shift left
.. The waterfall display will show funny frequencies on the bottom..ignore them and don't mess with the ham band buttons or you will lose the waterfall.

Then I started up another copy of SDR-RADIO and attached to my local SDR-IQ. I also connected to the same antenna. I centered the SDR-IQ freq to same as KX3 and voila! Both waterfalls pretty much matched. It looked like there was a spurious signal reflected off center at +- 40 kHz. It didn't move when I tuned freq. Probably need to use the I/Q balancing utility in SDR-RADIO.

I also ran the HDSDR app with KX3 input and got the same bandwidth pattern results..

Then I plugged the KX3 IQ into the iMic and connected to the USB on my laptop. I couldn't get more than 48kHz bandwidth. I am using the iMic on my iPad so it is good enough for now.

So if your laptop sound card can do 192k stereo per channel sample rate, you are probably good to go. Otherwise just buy one of the high performance USB sound cards (but NOT iMic).

So have fun.. now I am starting to think my SRD-IQ is redundant.

DJ - WK1K previously KB1YOO previously W8PID

The KX3, Flex 5000, and SDR-IQ at 192 kHz is a total YAWN and old technology!  Roll Eyes  Some of the modern SDRs can go up to 2 MHz or more.

Gene
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KB1YOO
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« Reply #67 on: December 21, 2012, 03:43:16 PM »

Gene
Actually the SDR-IQ samples the input at 66 MHz. The limiting factor is cramming the samples through the USB. So that's probably why only 192k. I think the newer SDR devices do simultaneous on board multiple channel demod with FPGAs. But now that's getting expensive. 192k is big enough bw for my poor addled brain to see what's around. So not the best but good enuf for amateur work!

DJ WK1K previously known as...this & that
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WA6MJE
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Posts: 71




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« Reply #68 on: December 21, 2012, 07:27:57 PM »

I just got a KX3 and will be configuring it for SDR over the holidays.  A month or so back I also got a Flex 1500.  My goal is to observe more bandwidth at a time hoping to locate more DX faster, mostly in the CW digital end of the bands.  When I got the Flex I was not aware it was limited to 48Khz bandwidth.  And, as posted above, some of the newer SDR systems have 2Mhz bandwidth.  I am considering how I would use that. 

The announced Flex 6500 is supposed to see multiple slices at a time which would be nice. BUT, now I am factoring my antennas into the equation.  I have to hide them, so I have several screwdriver verticals, magnetic loops and solutions that have very narrow bandwidth.  So, my limiting factor is antenna bandwidth rather than SDR bandwidth.  I can change the resonance of any of my antennas but that takes time and effort and sometimes a trip outside, so my antenna bandwidth limits minimizes the benefits of wideband SDR waterfalls for me.

So instead of thinking about the Flex 6500, I am now wondering if I would have a more efficient system if I just ran two or three independent rigs with two or three antennas at a time. 

For example, I can setup my "old" Icom 7000 on the JT 65 spot on one band, and the SSB mode is wide enough to see all I want within that one mode.  I can tune one of my antennas for that spot, and spend all day watching one band without touching anything. I can then take my Flex and watch the low end of the CW portion of that same band and use a second screwdriver antenna.  I can do the same with my KX3 using a third antenna, perhaps one of my magnetic loops.  These would all be slaved to laptops I have around the house.  With the three rigs going at once, I can be very efficient in terms of being in the right place at the right time. 

On the other hand, a wideband Flex 6500 with any of my antennas would require work to move from one spot to another.  Perhaps I can use an antenna tuner, which I have never done.  But with QRP, inefficient stealth antennas, I hate to introduce more inefficiency into my antenna designs.

In any event, I now have the three rigs to play with, and several months before the big Flex is ready for sale to determine what my dream station will be.

So I wonder how others use a SDR with enough bandwidth to see a whole band at once, but an antenna with say a 50 Khz 2.0 or lower SWR bandwidth?  It is like a round peg and a square hole.  Or, is there a way to make it work?

Rene - WA6MJE
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WD5GWY
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Posts: 383




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« Reply #69 on: December 21, 2012, 08:17:04 PM »

The SWR bandwidth won't effect reception enough for you to notice. Especially if the antenna(s) are still close to resonate on the band(s) you are using. Problems will arise when you transmit into a higher SWR(antenna too far out of resonance) than your radio(s) will tolerate.
  Using an SDR radio is fun ( I too have a Flex 1500). But, even though the display will show you
signals up and down the band.(within the bandwidth of the receiver) It won't tell you if the station(s) are DX stations or not. You will still have to tune them in. (point and click in the case of an SDR radio)
  The SDR radios mentioned that have 2Mhz bandwidth are receivers, not transceivers. They would be fine for monitoring, but, you'll still have to use another radio for transmit.  Personally, I cannot listen to more than one or two rigs at most, at any time. While the features of the new Flex 6000 Series Radios are great, how many people would use 4 to 8 receivers at one time?  How would you hear them all at once? The mockup software that Flex Radio shows at hamfests, shows several panadapter displays at once on a single screen, but, since it is only mockup software, no audio from any of the "slices".  And the new Flex radios are supposed to do 70Mhz of spectrum at once. (divided up into as much as 4 to 8 slices depending on which radio you have)
   Even then, with so much more bandwidth, you still won't be able to locate DX any faster.
An easier solution for that is keeping tabs on some of the DX Cluster websites and watching when someone spots a DX station. Of course, tons of other operators are doing the same thing and will pounce on them too!
  You could use a program like CW Skimmer to monitor the CW portion of the band to find DX contacts that way. It shows callsigns for multiple stations as it scans the band. Pretty cool too.
Have fun.
james
WD5GWY
     
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KE5JPP
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« Reply #70 on: December 22, 2012, 04:30:12 AM »

Gene
Actually the SDR-IQ samples the input at 66 MHz. The limiting factor is cramming the samples through the USB. So that's probably why only 192k. I think the newer SDR devices do simultaneous on board multiple channel demod with FPGAs. But now that's getting expensive. 192k is big enough bw for my poor addled brain to see what's around. So not the best but good enuf for amateur work!

DJ WK1K previously known as...this & that

Yes, I am aware that the SDR-IQ samples at 66 MHz.  USB is not the excuse since other SDRs can pass at least 2 MHz of bandwidth over USB.  The reason the SDR-IQ is limited to 190 kHz is because of a poor choice in USB interface chip.

Gene
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WA6MJE
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Posts: 71




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« Reply #71 on: December 22, 2012, 02:04:31 PM »

  You could use a program like CW Skimmer to monitor the CW portion of the band to find DX contacts that way. It shows callsigns for multiple stations as it scans the band. Pretty cool too.
Have fun.
james
WD5GWY
James.  I agree that I could not listen to more than a couple of receivers at a time. But, after I started using JT-65 HF I got lazy.  That software listens only to about 3Khz at a time, and all of the stations fit into that.  I can watch and listen to all of them at once (on a single band) and that is how I got used to the JT 65 "mini panadapter" and wanted now more. And with JT-65 I found an add on product called JT Alert.  That one scans my log, decides what DX/State/Country/Zone/Grid Square I need, looks up the call signs it sees and alerts me to come to the computer and pay attention.  Until I am alerted, I am free to do anything I want such as pay attention to other modes/bands.  I then found CW Skimmer, but have not used it yet.  I need to get my CW speed back up to what it was years ago.  I am not sure if CW Simmer will integrate with my log, and analyze what I need like JT Alert does, but my hope is to get the same functionality.  CW Skimmer can listen to more than the 3Khz that JT 65 can watch, so that brought me to start learning about SDR where I can watch the entire CW portion of one band.

So my big plan is to use SDR, plus CW Skimmer, plus JT 65, plus spotting websites, and use technology to cut down on my workload so I can perhaps get on top of what is going on on the two best bands of the day. I am not sure if the design will be using the Flex 6500 in some way, or the three rigs I have including the KX3.  It takes a lot of time and trial and error to get the software all to work together and talk together. 

Another way  to explain my plan is this.  I also fly airplanes.  Decades ago when I started flying the technology in the cockpit was Spartan, and the pilot had to do everything by hand, navigate with paper maps, compute with a hand held flight computer, set VOR dials to track radials and so on.  Today, we have GPS systems that cut down on the workload. Now I put in all the waypoints into the GPS, and the GPS takes it from there with an autopilot allowing the pilot to concentrate on more important tasks. 

So I am hoping I can use technology to handle the tasks of DX stalking, moving from station to station, finding out who the are, deciding if I need them or not and so on.  My role is the use "skill" to design the workstation, plan the bands and modes for the day, manage the pileup, improve antennas, hardware and software over the months and years.   I want the same thing I have with JT 65 and JT Alert, but with coverage over the CW portion, PSK 31 portion, of the first and second hottest bands of the day.

Not sure what hardware can meet the concept design. Now I am worried more about antenna bandwidth restrictions than SDR, but by trial and error I will improve the efficiency of my workstation. And concerned about using three rigs, or one humongous SDR rig with four slices.  I am not sure how many antenna ports the Flex 6500 will have either.  So, it will be several months after it ships that I can get enough feedback about how it works before I hit the buy button.  For now, the Flex 1500 and KX3 will be "two slices" of a big pie.

Rene - WA6MJE
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WD5GWY
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« Reply #72 on: December 22, 2012, 02:32:56 PM »

Sounds like a lot of work to me!  Grin
Of course I am more of a casual DX'er and not hard core at all.
I enjoy spinning the dial of an old boat anchor rig and seeing what
I find. Or using my Flex 1500 to to click and go. To me, half the fun
in tuning the bands is finding that station that no one else has found
yet. I have had that happen quite a bit over the years and even now
with the internet being used for DX spotting, I can still find stations
before someone spots them and creates a huge pileup.
  To me it is like what Forrest Gump said" Life is like a box of chocolates.
You just never know what you're going to find". I look at my style of
DX'ing in the same manner. Tune around and enjoy the surprise!
  james
WD5GWY

Oh, I understand the thing about flying. But, at the same time, isn't
flying the plane the main objective? If you are off doing something
else and the Auto Pilot decides it would be fun to do a dive, that could
get quite interesting in a hurry!

 
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KB1YOO
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« Reply #73 on: January 04, 2013, 06:00:12 PM »

Gene, you are absolutely right! I just did some more research and found current SDR tech (high priced) is doing 8 MS/sec into USB 2.0.

So now I see some people sampling the analog IQ output using 24 bit A/D sound cards and think they are getting high resolution dynamic range. I am wondering what the original analog IQ output is derived from. Is it 14bit? If so these guys are fooling themselves. Does anyone know?

Regards all for a 73 New Year
DJ WK1K/ex-KB1YOO/W8PID
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NI0Z
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« Reply #74 on: January 04, 2013, 06:33:09 PM »

Gene, you are absolutely right! I just did some more research and found current SDR tech (high priced) is doing 8 MS/sec into USB 2.0.

So now I see some people sampling the analog IQ output using 24 bit A/D sound cards and think they are getting high resolution dynamic range. I am wondering what the original analog IQ output is derived from. Is it 14bit? If so these guys are fooling themselves. Does anyone know?

Regards all for a 73 New Year
DJ WK1K/ex-KB1YOO/W8PID

Keep in mind that when you sample, regardless of source quality, you are dealing with loss.  That's why sampling at a greater bit width is always better than a smaller one, you loose less of the original artifact.

I would agree you can't turn an original 14 bits into 24 bits by revamping at a higher rate.  It would be like say you can produce more light by reflecting it with mirrors.
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