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Author Topic: SDR Knobs and Buttons in the future  (Read 118964 times)
K5TED
Member

Posts: 1261




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« Reply #45 on: September 15, 2013, 06:16:14 PM »

Latency with SDR is a non-issue except for CW.

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AB2YC
Member

Posts: 54




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« Reply #46 on: September 18, 2013, 06:18:19 AM »

To the OP congratulations on getting your License.

I also have been in the IT field for over 20 years and realize PCs will be with us for some time.

It was SDR that drew me back into ham radio, it truly is the future.
You will always find those who resist change, just side step them and move on.

One point where SDR shines is the ability to quickly change the entire interface by just changing the computer controlling it.
I foresee a point where the manufactures will offer a control head that will basically be the interface replacing the PC.
and an example of this is the K3 by Elecraft, my understanding is that it is actually a SDR based radio with a hard interface.

Being and IT guy myself I don't have a real issue with the PC interface and find it a whole lot easier to do all the inter-connections
"Virtually" (serial, audio, etc), need another port just add another "Virtual" one (I don't need to open the case or run a cable).

I would suspect that most IT guys or technology guys would not have an issue with SDR, we already understand that you need a
decent PC with a clean OS. I'm more of a Linux guy when it comes to apps requiring computer control of hardware (I also run CNC).
I was a bit reluctant at first to use MS Windows to run a radio, but it (my Flex-1500) has been running fine for me so that reluctance is gone.

Again congratulations on getting your license, and welcome to the world of SDR.





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N4OI
Member

Posts: 282




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« Reply #47 on: September 18, 2013, 07:00:22 PM »

Latency with SDR is a non-issue except for CW.

For some of us, this statement effectively reads, "Latency with SDR is a non-issue except for [ham radio]."

73
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K5TED
Member

Posts: 1261




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« Reply #48 on: September 18, 2013, 09:46:50 PM »

Latency with SDR is a non-issue except for CW.

For some of us, this statement effectively reads, "Latency with SDR is a non-issue except for [ham radio]."

73

Low ground clearance of the Corvette is a non-issue except for off-roading.
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N4OI
Member

Posts: 282




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« Reply #49 on: September 19, 2013, 04:16:49 AM »

Latency with SDR is a non-issue except for CW.

For some of us, this statement effectively reads, "Latency with SDR is a non-issue except for [ham radio]."

73

Low ground clearance of the Corvette is a non-issue except for off-roading.

And you will not find off-roading anywhere in the Corvette's published features or specs -- perhaps SDR vendors should re-label their CW buttons to "Amp Tune" ...   Grin

73
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W1JKA
Member

Posts: 2041




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« Reply #50 on: September 19, 2013, 04:50:25 AM »

  SDR newbie here, what kind of performance could I expect if I put an SDR mobile in my corvette and limited myself to secondary roads only? I plan to use a screwdriver for an antenna. Thanks
« Last Edit: September 19, 2013, 05:00:49 AM by W1JKA » Logged
K9IUQ
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Posts: 2630




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« Reply #51 on: September 19, 2013, 07:10:34 AM »

perhaps SDR vendors should re-label their CW buttons to "Amp Tune" ...   Grin

Perhaps it would be EVEN better if they eliminated the CW button,FSK button,and Digi buttons..

SDRs are for SSBers who like to brag and tell everyone how great their radio/audio works.. All other hams need not apply.

Stan K9IUQ
« Last Edit: September 19, 2013, 07:27:32 AM by K9IUQ » Logged
K5TED
Member

Posts: 1261




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« Reply #52 on: September 20, 2013, 06:26:53 PM »

Perhaps those who can't operate SDR's shouldn't purchase them. We'll still talk to them. Some of us may use CW when we "talk" to them. We will undoubtedly be using much superior SDR/Digi setups than a typical knob rig/patch cord/external modem/isolation transformer concoction user. We won't need a patch cord. It'll just flow, trouble-free, digitally from PC to SDR.

Nice.

It's really the only way to go unless you insist on touching just two wires together to communicate. Nothing wrong with that, but it's a bit beneath the technological advantages of an SDR.
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K5TED
Member

Posts: 1261




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« Reply #53 on: September 20, 2013, 06:32:24 PM »

Latency with SDR is a non-issue except for CW.

For some of us, this statement effectively reads, "Latency with SDR is a non-issue except for [ham radio]."

73


Low ground clearance of the Corvette is a non-issue except for off-roading.

And you will not find off-roading anywhere in the Corvette's published features or specs -- perhaps SDR vendors should re-label their CW buttons to "Amp Tune" ...   Grin

73

True. What you will find is a gearshifter that has the same designations as a Jeep gearshifter. Totally different vehicles. Same "D" on the shifter. (or 1, 2, 3, 4, etc.)

Perhaps Chevrolet should relabel the "D" to "Go Really Fast" and Jeep should relabel to "Go Really Slow Up A Telephone Pole"
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N4OI
Member

Posts: 282




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« Reply #54 on: September 20, 2013, 08:17:29 PM »

Latency with SDR is a non-issue except for CW.

For some of us, this statement effectively reads, "Latency with SDR is a non-issue except for [ham radio]."

73


Low ground clearance of the Corvette is a non-issue except for off-roading.

And you will not find off-roading anywhere in the Corvette's published features or specs -- perhaps SDR vendors should re-label their CW buttons to "Amp Tune" ...   Grin

73

True. What you will find is a gearshifter that has the same designations as a Jeep gearshifter. Totally different vehicles. Same "D" on the shifter. (or 1, 2, 3, 4, etc.)

Perhaps Chevrolet should relabel the "D" to "Go Really Fast" and Jeep should relabel to "Go Really Slow Up A Telephone Pole"

My Jeep does indeed have a "D" on the "gear shifter," but it also has another lever connected to a military-grade transfer case to select from three variations of 4WD.  (All analogies break down at some point, but I love the legs this one has!)   Grin

73
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N4OI
Member

Posts: 282




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« Reply #55 on: September 21, 2013, 05:39:26 AM »

Latency with SDR is a non-issue except for CW.

For some of us, this statement effectively reads, "Latency with SDR is a non-issue except for [ham radio]."

73


Low ground clearance of the Corvette is a non-issue except for off-roading.

And you will not find off-roading anywhere in the Corvette's published features or specs -- perhaps SDR vendors should re-label their CW buttons to "Amp Tune" ...   Grin

73

True. What you will find is a gearshifter that has the same designations as a Jeep gearshifter. Totally different vehicles. Same "D" on the shifter. (or 1, 2, 3, 4, etc.)

Perhaps Chevrolet should relabel the "D" to "Go Really Fast" and Jeep should relabel to "Go Really Slow Up A Telephone Pole"

My Jeep does indeed have a "D" on the "gear shifter," but it also has another lever connected to a military-grade transfer case to select from three variations of 4WD.  (All analogies break down at some point, but I love the legs this one has!)   Grin

73

Oh, and I think one of the 4WD options is labeled "QSK"  Grin !!
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W6RMK
Member

Posts: 680




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« Reply #56 on: September 21, 2013, 07:27:33 AM »

Ah, you mean low latency, not realtime, definitions matter when discussing this stuff....



In the context of a radio, for SSB latency of the up to say 50ms or so level is clearly a non issue, same for most data modes, as long as it is compensated for some of the EME modes.

CW is probably the only place it matters, and there are well known ways to solve this or at least to give the operator a choice of trade offs (Linear phase filters will ALWAYS introduce more group delay then non linear phase ones for example).

Low latency audio is a very tough problem on PCs, it can be done, but man what a pain.

Latency, on the RF path to the other end, is almost a non-issue regardless of mode *as long as the latency is constant*.  It takes 100 ms to propagate to the other side of the world, so adding 10-20-30 or even 100 ms isn't going to make a huge difference.

If the latency on the RF path varies randomly, though, it makes it very difficult to copy CW.

Where most people object to the latency thing is when trying to monitor their own CW transmission using a receiver.  There, the tens of ms latency bites you, because it's far enough out of sync to confuse you (the "singing on the PA in a stadium without earplugs" problem).

One can use a keyer or generate the sidetone some other way, but then you aren't listening to your own signal.
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N4OI
Member

Posts: 282




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« Reply #57 on: September 23, 2013, 02:27:21 AM »

Ah, you mean low latency, not realtime, definitions matter when discussing this stuff....



In the context of a radio, for SSB latency of the up to say 50ms or so level is clearly a non issue, same for most data modes, as long as it is compensated for some of the EME modes.

CW is probably the only place it matters, and there are well known ways to solve this or at least to give the operator a choice of trade offs (Linear phase filters will ALWAYS introduce more group delay then non linear phase ones for example).

Low latency audio is a very tough problem on PCs, it can be done, but man what a pain.

Latency, on the RF path to the other end, is almost a non-issue regardless of mode *as long as the latency is constant*.  It takes 100 ms to propagate to the other side of the world, so adding 10-20-30 or even 100 ms isn't going to make a huge difference.

If the latency on the RF path varies randomly, though, it makes it very difficult to copy CW.

Where most people object to the latency thing is when trying to monitor their own CW transmission using a receiver.  There, the tens of ms latency bites you, because it's far enough out of sync to confuse you (the "singing on the PA in a stadium without earplugs" problem).

One can use a keyer or generate the sidetone some other way, but then you aren't listening to your own signal.

I do not believe the issue is the inability to listen to one's own signal.  There is just no way to compensate for significant latency, whether constant or not, and still have good QSK...  After experiencing QSK from a K3 or any of the older Ten-Tec radios, you're not going to "keep 'em down on the farm" with a keyer-generated sidetone either.....   

73

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M0HCN
Member

Posts: 497




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« Reply #58 on: September 23, 2013, 11:05:26 AM »

The key question is what is significant?

I would guess that 10ms (as long as it is constant) probably is not significant (That is going to be in the ballpark for vacuum relay T/R switch and rx desense recovery time on a conventional rig, and actually a well crafted PC program should come close to this as long as the network frames are not too big.

20ms, 50ms? I have no idea, but I would bet the threshold is greater then 10ms for almost everyone and greater then 20ms for the vast majority of ops. 

Regards, Dan.
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K5TED
Member

Posts: 1261




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« Reply #59 on: September 23, 2013, 10:05:15 PM »

If the main objection to SDR is that CW ops can't listen to their own clicks, then I'd add this...

For about 15 years, I was accustomed to listening to myself over an air monitor. That way, I could hear myself as heard by listeners. With the advent of digital STL links, the latency was enough to make realtime listening impossible. We adjusted to listening to ourselves off console audio.

With the present SDR tech, and the inherent latency, it is impossible to listen live.

The overwhelming majority of amateur grade xcvrs do not offer a "MONITOR" function, yet we get along just fine.

It seems as if the insistence of CW ops to have the ability to listen to themselves "realtime" is just a crutch and excuse to malign current SDR tech.

Use a keyer and get along, or get left behind.

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