Re: Clocked Morse Part 2 Detection
Daniel,
Yes, one can skip the square root for the individual dit frames simply by dividing alpha by the standard deviation of the QRN. But there's still one square root required.
Thanks for collecting the papers.
Have Fun!
Reg
On Monday, March 25, 2024 at 11:08:04 PM CDT, Daniel Ricardo Perez LW1ECP via groups.io <danyperez1@...> wrote:
"Computing the mean and standard deviation for a dit frame is very low cost and very easy to implement in a DSP setting on an MCU. Computational cost is one multiply and 2 sums per frame sample plus 3 multiplications, a sum and square root per dit frame.". Wow, implementing this math is too heavy for my taste. Anyway, if I didn't get it wrong, if after calculating the square root there comes a level comparison, I think you can use the variance you mentioned instead of the standard deviation with no problem. This way you save extracting a square root, the most involved step. Is this correct? As to Hayward's articles on CCW, there are some of them (thanks to George N2APB) in: https://midnightdesignsolutions.com/ccw/ccw_news/ As there are more than 120 text files, I downloaded the whole subpage and uploaded it as a .zip to: /g/qrptech/files/ccw_news.zip Downloading and decompressing it, one can make a search for "Hayward" or whatever on all the files. I'm afraid, however, that some issues and pictures are missing. Daniel Perez LW1ECP 24 de marzo de 2024, 11:42:32 ART, Reginald Beardsley via groups.io <pulaskite@...> escribi¨®: In the CCW articles I recall by Wes Hayward,? (but can't find #$%$) CCW was described as integrating over dit frames and comparing the sums.? However, I recall no mention of how much of a difference in level constituted a signal. That was where I started a month or so ago at implementing CCW and QRSS.? The problem was I had no way to calculate expected results ready to hand.? So I stepped back and thought about the concept,? "the power level in this dit frame is different from this other dit frame" and how best to measure that in real time at minimum cost.? That led me back to basic physics, probability theory and statistics.? Because of my seismic background my first inclination is to slap things around with some transforms.? But that is not MCU friendly. Computing the mean and standard deviation for a dit frame is very low cost and very easy to implement in a DSP setting on an MCU.? Computational cost is one multiply and 2 sums per frame sample plus 3 multiplications, a sum and square root per dit frame.? Then make a decision based on measured statistics of the QRN whether to emit an audio tone or not.? It introduces a single dit frame latency.? The output is either a pure side tone signal or silence.? No hiss. In the absence of a signal, we expect the QRN to be a Gaussian random process in the BW of the channel.? More particularly, we have an expectation of both the mean and the variance. By initializing the receiver for 10 seconds on frequency to record actual QRN and determine the mean and standard deviation we now have a statistical criterion by which to eliminate QRN.? ? By setting a threshold value for the mean value at a specified standard deviation we can distinguish if a very low amplitude signal is present in addition to the noise.? As the Gaussian is well tabulated one can set the threshold for any desired level of spurious noise as a BER in? percentage probability. The clock frame timing is the key to making it work.? If the receiving dit frame is off by 50% there will be no change.? Hence the need for synchronization.? That will be a separate topic. The standard deviation of the dit frame comes in to play in the presence? of QRM.? By tracking? the variance of the variance, one can subject noisy dit frames to a different criterion based on the variance.? If only a constant sinusoidal signal is present, the change in variance will be small.? If a dit frame has a noise burst present, the increase in the variance can be used to select a different threshold level or other processing. An effective QRM filter for rejecting periodic noise bursts could be developed on top of the basic clocked frame by developing another layer for burst noise based on the variance of the dit frame estimates of the mean and standard deviation among frames.? ? ? ? ? ? Have Fun! Reg? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?
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Re: Clocked Morse Part 2 Detection
"Computing the mean and standard deviation for a dit frame is very low cost and very easy to implement in a DSP setting on an MCU. Computational cost is one multiply and 2 sums per frame sample plus 3 multiplications, a sum and square root per dit frame.". Wow, implementing this math is too heavy for my taste. Anyway, if I didn't get it wrong, if after calculating the square root there comes a level comparison, I think you can use the variance you mentioned instead of the standard deviation with no problem. This way you save extracting a square root, the most involved step. Is this correct? As to Hayward's articles on CCW, there are some of them (thanks to George N2APB) in: https://midnightdesignsolutions.com/ccw/ccw_news/ As there are more than 120 text files, I downloaded the whole subpage and uploaded it as a .zip to: /g/qrptech/files/ccw_news.zip Downloading and decompressing it, one can make a search for "Hayward" or whatever on all the files. I'm afraid, however, that some issues and pictures are missing. Daniel Perez LW1ECP 24 de marzo de 2024, 11:42:32 ART, Reginald Beardsley via groups.io <pulaskite@...> escribi¨®: In the CCW articles I recall by Wes Hayward,? (but can't find #$%$) CCW was described as integrating over dit frames and comparing the sums.? However, I recall no mention of how much of a difference in level constituted a signal. That was where I started a month or so ago at implementing CCW and QRSS.? The problem was I had no way to calculate expected results ready to hand.? So I stepped back and thought about the concept,? "the power level in this dit frame is different from this other dit frame" and how best to measure that in real time at minimum cost.? That led me back to basic physics, probability theory and statistics.? Because of my seismic background my first inclination is to slap things around with some transforms.? But that is not MCU friendly. Computing the mean and standard deviation for a dit frame is very low cost and very easy to implement in a DSP setting on an MCU.? Computational cost is one multiply and 2 sums per frame sample plus 3 multiplications, a sum and square root per dit frame.? Then make a decision based on measured statistics of the QRN whether to emit an audio tone or not.? It introduces a single dit frame latency.? The output is either a pure side tone signal or silence.? No hiss. In the absence of a signal, we expect the QRN to be a Gaussian random process in the BW of the channel.? More particularly, we have an expectation of both the mean and the variance. By initializing the receiver for 10 seconds on frequency to record actual QRN and determine the mean and standard deviation we now have a statistical criterion by which to eliminate QRN.? ? By setting a threshold value for the mean value at a specified standard deviation we can distinguish if a very low amplitude signal is present in addition to the noise.? As the Gaussian is well tabulated one can set the threshold for any desired level of spurious noise as a BER in? percentage probability. The clock frame timing is the key to making it work.? If the receiving dit frame is off by 50% there will be no change.? Hence the need for synchronization.? That will be a separate topic. The standard deviation of the dit frame comes in to play in the presence? of QRM.? By tracking? the variance of the variance, one can subject noisy dit frames to a different criterion based on the variance.? If only a constant sinusoidal signal is present, the change in variance will be small.? If a dit frame has a noise burst present, the increase in the variance can be used to select a different threshold level or other processing. An effective QRM filter for rejecting periodic noise bursts could be developed on top of the basic clocked frame by developing another layer for burst noise based on the variance of the dit frame estimates of the mean and standard deviation among frames.? ? ? ? ? ? Have Fun! Reg? ? ? ? ? ? ? ? ? ? ? ? ? ? ? ?
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Re: Suppression of QRN via clock aligned Morse symbols
LoL! :-)
That paragraph tells me *quite* a lot. We think very much alike. I started and then aborted a post about using rise and fall time to increase the BW of a low keying rate signal.
In rough terms, by shaping the pulse edges appropriately one could add a number of harmonically related frequencies sending the same information in a controlled bandwidth.
Modern encoding systems offer many advantages. Morse has the advantage of being legal everywhere amateur radio is allowed without any special approvals. And low power is also legal.
A major goal for 40 years is reliable 2 kB message transfer US to Oz per day at 10 mW ERP. Time for me to find Shannon and determine if that's actually possible.
Have Fun!
Reg
On Sunday, March 24, 2024 at 06:25:33 PM CDT, Daniel Marks <profdc9@...> wrote:
No you should just have to click the "Download" link (down arrow icon) at the upper left part of the web page to download the PDF.
I would include it here, but I'd rather have the link to the most recent version available.
The idea of SCAMP is to be simple enough to implement on an 8-bit processor but include synchronous timing and forward error correction.? I use both OOK and FSK, but FSK has an advantage because it can send double the power, and it is much less susceptible to fading as one is comparing two channels that are fading about the same, vs. measuring the amplitude of one channel that can vary continuously because of fading.
73,
Dan KW4TI
On Sun, Mar 24, 2024 at 4:35?PM Reginald Beardsley via <pulaskite= [email protected]> wrote: Daniel,
Very cool project.? I'd been planning to design a radio for this project and then realized Hans already had one on the market.? It just needs more software.
The things you can do by filtering in both the time and frequency domains simultaneously are quite powerful.
Do I need to sign in to github to retrieve the PDF?
Have Fun!
Reg
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Re: Suppression of QRN via clock aligned Morse symbols
No you should just have to click the "Download" link (down arrow icon) at the upper left part of the web page to download the PDF.
I would include it here, but I'd rather have the link to the most recent version available.
The idea of SCAMP is to be simple enough to implement on an 8-bit processor but include synchronous timing and forward error correction.? I use both OOK and FSK, but FSK has an advantage because it can send double the power, and it is much less susceptible to fading as one is comparing two channels that are fading about the same, vs. measuring the amplitude of one channel that can vary continuously because of fading.
73,
Dan KW4TI
On Sun, Mar 24, 2024 at 4:35?PM Reginald Beardsley via <pulaskite= [email protected]> wrote: Daniel,
Very cool project.? I'd been planning to design a radio for this project and then realized Hans already had one on the market.? It just needs more software.
The things you can do by filtering in both the time and frequency domains simultaneously are quite powerful.
Do I need to sign in to github to retrieve the PDF?
Have Fun!
Reg
|
Re: Suppression of QRN via clock aligned Morse symbols
Daniel,
Very cool project. I'd been planning to design a radio for this project and then realized Hans already had one on the market. It just needs more software.
The things you can do by filtering in both the time and frequency domains simultaneously are quite powerful.
Do I need to sign in to github to retrieve the PDF?
Have Fun!
Reg
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Re: Suppression of QRN via clock aligned Morse symbols
Reg,
Understood. I will look forward to your work with the QMX.
73 Mike N2MS
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On 03/24/2024 11:04 AM EDT Reginald Beardsley via groups.io <pulaskite@...> wrote:
Mike,
The fact that it lets you head copy very weak signals without having to listen to the hiss of the QRN seems rather valuable in something such as the QMX. The synchronization to the sender is a per QSO link initiation that accounts for propagation delay and station clock sync. Once that's been done all transmissions will be in sync.
The sender's sidetone is asynchronous, but the transmit keying is delayed by at most a single dit frame. Detection imposes another dit frame latency. But because the receiver has no reference for the start of the keying by the sender, just the emitted signal, it's transparent.
For QRSS mode you would key your message into a buffer at a comfortable rate which you could edit as one does message memories for contests. The radio would then send the message at 1-10 s dit frame rates. The receiving station would then play back the buffer contents using the side tone at the end of message or on command from the buffer.
My goal was digital mode performance without a computer other than the MCU in the QMX. Then I realized *any* keyer/decoder could implement a protocol this simple. That makes it easy for any radio to use CCW/QRSS modes. Thus this effort to lay out all the details and get it implemented in at least the K3NG and Morserino.
Have Fun!
Reg
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Re: Suppression of QRN via clock aligned Morse symbols
Mike,
The fact that it lets you head copy very weak signals without having to listen to the hiss of the QRN seems rather valuable in something such as the QMX. The synchronization to the sender is a per QSO link initiation that accounts for propagation delay and station clock sync. Once that's been done all transmissions will be in sync.
The sender's sidetone is asynchronous, but the transmit keying is delayed by at most a single dit frame. Detection imposes another dit frame latency. But because the receiver has no reference for the start of the keying by the sender, just the emitted signal, it's transparent.
For QRSS mode you would key your message into a buffer at a comfortable rate which you could edit as one does message memories for contests. The radio would then send the message at 1-10 s dit frame rates. The receiving station would then play back the buffer contents using the side tone at the end of message or on command from the buffer.
My goal was digital mode performance without a computer other than the MCU in the QMX. Then I realized *any* keyer/decoder could implement a protocol this simple. That makes it easy for any radio to use CCW/QRSS modes. Thus this effort to lay out all the details and get it implemented in at least the K3NG and Morserino.
Have Fun!
Reg
|
Clocked Morse Part 2 Detection
In the CCW articles I recall by Wes Hayward, (but can't find #$%$) CCW was described as integrating over dit frames and comparing the sums. However, I recall no mention of how much of a difference in level constituted a signal.
That was where I started a month or so ago at implementing CCW and QRSS. The problem was I had no way to calculate expected results ready to hand. So I stepped back and thought about the concept, "the power level in this dit frame is different from this other dit frame" and how best to measure that in real time at minimum cost. That led me back to basic physics, probability theory and statistics. Because of my seismic background my first inclination is to slap things around with some transforms. But that is not MCU friendly.
Computing the mean and standard deviation for a dit frame is very low cost and very easy to implement in a DSP setting on an MCU. Computational cost is one multiply and 2 sums per frame sample plus 3 multiplications, a sum and square root per dit frame. Then make a decision based on measured statistics of the QRN whether to emit an audio tone or not. It introduces a single dit frame latency. The output is either a pure side tone signal or silence. No hiss.
In the absence of a signal, we expect the QRN to be a Gaussian random process in the BW of the channel. More particularly, we have an expectation of both the mean and the variance.
By initializing the receiver for 10 seconds on frequency to record actual QRN and determine the mean and standard deviation we now have a statistical criterion by which to eliminate QRN. By setting a threshold value for the mean value at a specified standard deviation we can distinguish if a very low amplitude signal is present in addition to the noise. As the Gaussian is well tabulated one can set the threshold for any desired level of spurious noise as a BER in percentage probability.
The clock frame timing is the key to making it work. If the receiving dit frame is off by 50% there will be no change. Hence the need for synchronization. That will be a separate topic.
The standard deviation of the dit frame comes in to play in the presence of QRM. By tracking the variance of the variance, one can subject noisy dit frames to a different criterion based on the variance. If only a constant sinusoidal signal is present, the change in variance will be small. If a dit frame has a noise burst present, the increase in the variance can be used to select a different threshold level or other processing.
An effective QRM filter for rejecting periodic noise bursts could be developed on top of the basic clocked frame by developing another layer for burst noise based on the variance of the dit frame estimates of the mean and standard deviation among frames.
Have Fun!
Reg
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Re: Suppression of QRN via clock aligned Morse symbols
Reg,
I am aware of CCW by the work of Ray Petit years ago but what is the advantage of CCW over more modern modes such as PSK-31 or JSCall? The only advantage I see is that one can decode the signal by ear if it is not too buried in the noise.
I asked about synchronization and preamble because some of my transmissions are short, such as R R or QSL QSL. How many characters have to be received before you can process the data?
Finally, does the start time have to be synchronized to a clock? CW is asynchronous.
Personally I don't use a computer when operating CW or SSB since I do lots of portable operation. I still log by paper. I don't use digital modes but may try JSCall if I I need to send data.
Mike N2MS
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On 03/23/2024 5:55 PM EDT Reginald Beardsley via groups.io <pulaskite@...> wrote:
Mike,
The speed can be infinitely variable, but 12, 16 & 24 have proven comfortable speeds and appears to be the range for most people who hand key. It's also convenient frame rates 100, 75 and 50 ms. Sychronization is via a PRN with optimal correlation properties.
My apologies for having made my post a bit obtuse. I wanted to introduce the concept as briefly as possible, but didn't organize it well. This is probably explanation attempt number 20 something. It's super simple once you get the idea. Clearly I did not get the presentation right.
Please post further questions to the list after you've reread the original post a time or two as I clearly ordered the ideas poorly. I'll expand on key points based on your questions. The Gold code sequence is an interesting side topic of critical value in the synchronization process. One could also use it for selective calling by means of a Gold code generated based on call sign. Gold introduced the concept of PRN bit streams with optimal correlation and cross correlation properties. Auto correlation a narrow spike and cross correlation among the set near zero.
Have Fun!
Reg
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Re: Suppression of QRN via clock aligned Morse symbols
Wow, that brings back memories. I was one of the SMEs on the SCAMP program: ? Single Channel Anti-Jam Man Portable (SCAMP) Terminal (U) Overview (U): (U) The SCAMP provides the tactical warfighter with a man-portable satellite communications system that is secure anti-jam protected, and has a lower probability of intercept and probability of detection. Mike B. Feher, N4FS 89 Arnold Blvd. Howell NJ 07731 848-245-9115 ?
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From: [email protected] < [email protected]> On Behalf Of Daniel Marks Sent: Saturday, March 23, 2024 11:19 PM To: [email protected]Subject: Re: [qex] Suppression of QRN via clock aligned Morse symbols ? I developed a protocol that uses OOK or BFSK as the modulation layer.? You can look at the specification here
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Re: Suppression of QRN via clock aligned Morse symbols
I developed a protocol that uses OOK or BFSK as the modulation layer.? You can look at the specification here
I made an effort to ensure that the protocol would maintain timing at the beginning and during a transmission.? I use a unique synchronization code with a low sidelobe autocorrelation at the beginning (and at periodic intervals within) the transmission, as well as sync bits placed at regular intervals, to maintain synchronization between the transmitter and receiver.
73, Dan KW4TI
On Sat, Mar 23, 2024 at 2:00?PM Reginald Beardsley via <pulaskite= [email protected]> wrote: Daniel,
Thank you. My copy of Shannon is MIA in my library, so I've relied on wikipedia :-( Big library, small book.
The statistical test I proposed is equivalent to integration, but much cleaner to implement in a statistically meaningful manner. A 10 second frame per dit won't move much data, but it will have excellent QRN immunity if the alpha term is near 3.
The BER of my criterion is readily calculated from alpha. You could set the threshold as BER instead of multiples of sigma. It would apply equally well to any modulation scheme which used cross correlation as a detection criterion. A pair of 10 second PRNs for 0 & 1? How much BW may I use? The power, time and bandwidth equation applies.
If you generate a pair of random bit streams with good cross correlation properties you can do RTTY at extremely low power levels by keying one or the other of the 2 sequences. Direct sequence spread spectrum RTTY. With secure rolling bitstreams completely impossible to detect or intercept.
Have Fun!
Reg
On Saturday, March 23, 2024 at 12:57:16 PM CDT, Daniel Marks < profdc9@...> wrote:
To understand better the Shannon limit of what you can send with on-off keying (which is what Morse Code is a special case of), you might want to look at this document
For example, looking at the M=2 curve (on-off modulation), the bit error rate at 9.5 dB Eb/N0 (energy per bit vs. noise density) is 0.01 .? This would be the best possible case for any on-off keying method that sends bits using on-off keying.? Coherent integration increases Eb/N0, which reduces bit error rate.
Dan
On Sat, Mar 23, 2024 at 10:50?AM Reginald Beardsley via <pulaskite= [email protected]> wrote: I've?been?working?on?the?general?concept?of?a?mashup?of?QRSS?and?CCW?in?earnest?for?the?last?few?weeks?and?have?an?algorithm?to?present.??The?algorithm?implements?a?statistical?non-linear?operator?which?eliminates?QRN?from?an?incoming?audio?stream.??The?output?is?a?clean?keyed?audio?tone.
The?Coherent?CW?concept?goes?back?many?years,?but?for?various?reasons?has?never?become?popular.??My?hope?is?this?will?change?that.
The?fundamental?notion?is?that?all?Morse?symbol?edges?sent?by?a?station?are?aligned?at?one?of?several?dit?frame?lengths.??100,?75?&?50?ms?for?12,?16?&?24?wpm?for?audio?QSOs?and?then?1-10?s?dit?frames?for?QRSS?message?transfer.
At?startup?on?an?unused?frequency,?the?receiver?listens?for?10?seconds?and?calculates?the?mean?value?and?standard?deviation?of?the?absolute?amplitude?to?produce?a?statistical?estimate?for?QRN.
Once?that?has?been?done?a?signal?is?detected?by?testing?the?mean?value?of?a?dit?frame?to?see?if?it?exceeds?a?threshold?of?alpha*sigma?+?the?mean?value of the QRN.??If?it?does?key?a?sidetone?dit.
For?optimal?performance,?the?clock?timing?at?the?receiving?station?needs?to?be?synchronized?to?the?incoming?signal.??The?initial?sync?is?best?done?by?using?a?Gold?code?dit?stream.??Gold?codes?have?the?property?that?they?have?optimal?correlation?properties?making?determining?propagation?delays??more?accurate.
Once??a?QSO?has?started,?every?Nth?character?that?gets?decoded?gets?a?resync?performed?by?FFT.
Keying?the?transmitter?requires?buffering?the?start?of?a?dit?or?dah?by?as?much?as?one?frame.??If?the?operator?heard?the?latency?while?keying?it?would?be?very?uncomfortable.??However,?only?the?receiving?station?hears?the?latency?and?it?doesn't?affect?them.??Sender?hears?normal?sidetone?and?receiver?hears?the?signal?with?at?most?a?single?dit?frame?delay?added?to?the?propagation?delay.
All?of?the?requisite?supporting?infrastructure?is?present?in?any?of?several?MCU?based?keyer?designs?such?as?the?K3NG,?Morserino,?etc.
I?have?guests?coming?for?the?eclipse,?so?I?won't?have?time?to?bring?up?a?development?environment?to?compile?one?of?the?keyer?codes?so?I?can?implement?the?changes,?but?from?the?description,?it?should?be?clear?this?is?not?a?complex?algorithm.
Have?Fun!
Reg
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The fundamental concept is that every symbol is precisely the same length and is time aligned with all the other symbols sent during a QSO by the sender. The sender does not need better than TCXO stability.
This requires :
Implementing a dit frame clock which can be set to various durations. High accuracy not required. Just stability.
Logic to align non-aligned input before output. User must hear side tone without latency. Receiving station can't detect latency.
Logic to set the alignment of the receiver dit frame for the statistical processing
Logic to compute the mean and standard deviation of the absolute amplitude of the receiver audio output during a dit frame.
Computing the FFT of a Gold code sync signal over a 10 s window and then doing a linear fit to the phase delay to align the dit frame
Periodically doing the FFT & linear regression to update the phase delay every Nth character
I *think* everything else is just a combination of the above, but I could easily have missed some minor things.
I think anyone with any embedded experience will see this is not difficult code to write.
Have Fun!
Reg
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Re: Suppression of QRN via clock aligned Morse symbols
Mike,
The speed can be infinitely variable, but 12, 16 & 24 have proven comfortable speeds and appears to be the range for most people who hand key. It's also convenient frame rates 100, 75 and 50 ms. Sychronization is via a PRN with optimal correlation properties.
My apologies for having made my post a bit obtuse. I wanted to introduce the concept as briefly as possible, but didn't organize it well. This is probably explanation attempt number 20 something. It's super simple once you get the idea. Clearly I did not get the presentation right.
Please post further questions to the list after you've reread the original post a time or two as I clearly ordered the ideas poorly. I'll expand on key points based on your questions. The Gold code sequence is an interesting side topic of critical value in the synchronization process. One could also use it for selective calling by means of a Gold code generated based on call sign. Gold introduced the concept of PRN bit streams with optimal correlation and cross correlation properties. Auto correlation a narrow spike and cross correlation among the set near zero.
Have Fun!
Reg
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Re: Suppression of QRN via clock aligned Morse symbols
Daniel,
Thank you. My copy of Shannon is MIA in my library, so I've relied on wikipedia :-( Big library, small book.
The statistical test I proposed is equivalent to integration, but much cleaner to implement in a statistically meaningful manner. A 10 second frame per dit won't move much data, but it will have excellent QRN immunity if the alpha term is near 3.
The BER of my criterion is readily calculated from alpha. You could set the threshold as BER instead of multiples of sigma. It would apply equally well to any modulation scheme which used cross correlation as a detection criterion. A pair of 10 second PRNs for 0 & 1? How much BW may I use? The power, time and bandwidth equation applies.
If you generate a pair of random bit streams with good cross correlation properties you can do RTTY at extremely low power levels by keying one or the other of the 2 sequences. Direct sequence spread spectrum RTTY. With secure rolling bitstreams completely impossible to detect or intercept.
Have Fun!
Reg
On Saturday, March 23, 2024 at 12:57:16 PM CDT, Daniel Marks <profdc9@...> wrote:
To understand better the Shannon limit of what you can send with on-off keying (which is what Morse Code is a special case of), you might want to look at this document
For example, looking at the M=2 curve (on-off modulation), the bit error rate at 9.5 dB Eb/N0 (energy per bit vs. noise density) is 0.01 .? This would be the best possible case for any on-off keying method that sends bits using on-off keying.? Coherent integration increases Eb/N0, which reduces bit error rate.
Dan
On Sat, Mar 23, 2024 at 10:50?AM Reginald Beardsley via <pulaskite= [email protected]> wrote: I've?been?working?on?the?general?concept?of?a?mashup?of?QRSS?and?CCW?in?earnest?for?the?last?few?weeks?and?have?an?algorithm?to?present.??The?algorithm?implements?a?statistical?non-linear?operator?which?eliminates?QRN?from?an?incoming?audio?stream.??The?output?is?a?clean?keyed?audio?tone.
The?Coherent?CW?concept?goes?back?many?years,?but?for?various?reasons?has?never?become?popular.??My?hope?is?this?will?change?that.
The?fundamental?notion?is?that?all?Morse?symbol?edges?sent?by?a?station?are?aligned?at?one?of?several?dit?frame?lengths.??100,?75?&?50?ms?for?12,?16?&?24?wpm?for?audio?QSOs?and?then?1-10?s?dit?frames?for?QRSS?message?transfer.
At?startup?on?an?unused?frequency,?the?receiver?listens?for?10?seconds?and?calculates?the?mean?value?and?standard?deviation?of?the?absolute?amplitude?to?produce?a?statistical?estimate?for?QRN.
Once?that?has?been?done?a?signal?is?detected?by?testing?the?mean?value?of?a?dit?frame?to?see?if?it?exceeds?a?threshold?of?alpha*sigma?+?the?mean?value of the QRN.??If?it?does?key?a?sidetone?dit.
For?optimal?performance,?the?clock?timing?at?the?receiving?station?needs?to?be?synchronized?to?the?incoming?signal.??The?initial?sync?is?best?done?by?using?a?Gold?code?dit?stream.??Gold?codes?have?the?property?that?they?have?optimal?correlation?properties?making?determining?propagation?delays??more?accurate.
Once??a?QSO?has?started,?every?Nth?character?that?gets?decoded?gets?a?resync?performed?by?FFT.
Keying?the?transmitter?requires?buffering?the?start?of?a?dit?or?dah?by?as?much?as?one?frame.??If?the?operator?heard?the?latency?while?keying?it?would?be?very?uncomfortable.??However,?only?the?receiving?station?hears?the?latency?and?it?doesn't?affect?them.??Sender?hears?normal?sidetone?and?receiver?hears?the?signal?with?at?most?a?single?dit?frame?delay?added?to?the?propagation?delay.
All?of?the?requisite?supporting?infrastructure?is?present?in?any?of?several?MCU?based?keyer?designs?such?as?the?K3NG,?Morserino,?etc.
I?have?guests?coming?for?the?eclipse,?so?I?won't?have?time?to?bring?up?a?development?environment?to?compile?one?of?the?keyer?codes?so?I?can?implement?the?changes,?but?from?the?description,?it?should?be?clear?this?is?not?a?complex?algorithm.
Have?Fun!
Reg
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Re: Suppression of QRN via clock aligned Morse symbols
Interesting. How does one synchronize with the CCW signal? Does a transmisdion have to use a synchronizing preamble or do the users agree on a fixed symbol rate, such as 20 words per minute?
?
Mike N2MS
On Sat, Mar 23, 2024 at 10:50?AM Reginald Beardsley via <pulaskite= [email protected]> wrote:
I've?been?working?on?the?general?concept?of?a?mashup?of?QRSS?and?CCW?in?earnest?for?the?last?few?weeks?and?have?an?algorithm?to?present.??The?algorithm?implements?a?statistical?non-linear?operator?which?eliminates?QRN?from?an?incoming?audio?stream.??The?output?is?a?clean?keyed?audio?tone.
The?Coherent?CW?concept?goes?back?many?years,?but?for?various?reasons?has?never?become?popular.??My?hope?is?this?will?change?that.
The?fundamental?notion?is?that?all?Morse?symbol?edges?sent?by?a?station?are?aligned?at?one?of?several?dit?frame?lengths.??100,?75?&?50?ms?for?12,?16?&?24?wpm?for?audio?QSOs?and?then?1-10?s?dit?frames?for?QRSS?message?transfer.
At?startup?on?an?unused?frequency,?the?receiver?listens?for?10?seconds?and?calculates?the?mean?value?and?standard?deviation?of?the?absolute?amplitude?to?produce?a?statistical?estimate?for?QRN.
Once?that?has?been?done?a?signal?is?detected?by?testing?the?mean?value?of?a?dit?frame?to?see?if?it?exceeds?a?threshold?of?alpha*sigma?+?the?mean?value of the QRN.??If?it?does?key?a?sidetone?dit.
For?optimal?performance,?the?clock?timing?at?the?receiving?station?needs?to?be?synchronized?to?the?incoming?signal.??The?initial?sync?is?best?done?by?using?a?Gold?code?dit?stream.??Gold?codes?have?the?property?that?they?have?optimal?correlation?properties?making?determining?propagation?delays??more?accurate.
Once??a?QSO?has?started,?every?Nth?character?that?gets?decoded?gets?a?resync?performed?by?FFT.
Keying?the?transmitter?requires?buffering?the?start?of?a?dit?or?dah?by?as?much?as?one?frame.??If?the?operator?heard?the?latency?while?keying?it?would?be?very?uncomfortable.??However,?only?the?receiving?station?hears?the?latency?and?it?doesn't?affect?them.??Sender?hears?normal?sidetone?and?receiver?hears?the?signal?with?at?most?a?single?dit?frame?delay?added?to?the?propagation?delay.
All?of?the?requisite?supporting?infrastructure?is?present?in?any?of?several?MCU?based?keyer?designs?such?as?the?K3NG,?Morserino,?etc.
I?have?guests?coming?for?the?eclipse,?so?I?won't?have?time?to?bring?up?a?development?environment?to?compile?one?of?the?keyer?codes?so?I?can?implement?the?changes,?but?from?the?description,?it?should?be?clear?this?is?not?a?complex?algorithm.
Have?Fun!
Reg
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Re: Suppression of QRN via clock aligned Morse symbols
To understand better the Shannon limit of what you can send with on-off keying (which is what Morse Code is a special case of), you might want to look at this document
For example, looking at the M=2 curve (on-off modulation), the bit error rate at 9.5 dB Eb/N0 (energy per bit vs. noise density) is 0.01 .? This would be the best possible case for any on-off keying method that sends bits using on-off keying.? Coherent integration increases Eb/N0, which reduces bit error rate.
Dan
On Sat, Mar 23, 2024 at 10:50?AM Reginald Beardsley via <pulaskite= [email protected]> wrote: I've?been?working?on?the?general?concept?of?a?mashup?of?QRSS?and?CCW?in?earnest?for?the?last?few?weeks?and?have?an?algorithm?to?present.??The?algorithm?implements?a?statistical?non-linear?operator?which?eliminates?QRN?from?an?incoming?audio?stream.??The?output?is?a?clean?keyed?audio?tone.
The?Coherent?CW?concept?goes?back?many?years,?but?for?various?reasons?has?never?become?popular.??My?hope?is?this?will?change?that.
The?fundamental?notion?is?that?all?Morse?symbol?edges?sent?by?a?station?are?aligned?at?one?of?several?dit?frame?lengths.??100,?75?&?50?ms?for?12,?16?&?24?wpm?for?audio?QSOs?and?then?1-10?s?dit?frames?for?QRSS?message?transfer.
At?startup?on?an?unused?frequency,?the?receiver?listens?for?10?seconds?and?calculates?the?mean?value?and?standard?deviation?of?the?absolute?amplitude?to?produce?a?statistical?estimate?for?QRN.
Once?that?has?been?done?a?signal?is?detected?by?testing?the?mean?value?of?a?dit?frame?to?see?if?it?exceeds?a?threshold?of?alpha*sigma?+?the?mean?value of the QRN.??If?it?does?key?a?sidetone?dit.
For?optimal?performance,?the?clock?timing?at?the?receiving?station?needs?to?be?synchronized?to?the?incoming?signal.??The?initial?sync?is?best?done?by?using?a?Gold?code?dit?stream.??Gold?codes?have?the?property?that?they?have?optimal?correlation?properties?making?determining?propagation?delays??more?accurate.
Once??a?QSO?has?started,?every?Nth?character?that?gets?decoded?gets?a?resync?performed?by?FFT.
Keying?the?transmitter?requires?buffering?the?start?of?a?dit?or?dah?by?as?much?as?one?frame.??If?the?operator?heard?the?latency?while?keying?it?would?be?very?uncomfortable.??However,?only?the?receiving?station?hears?the?latency?and?it?doesn't?affect?them.??Sender?hears?normal?sidetone?and?receiver?hears?the?signal?with?at?most?a?single?dit?frame?delay?added?to?the?propagation?delay.
All?of?the?requisite?supporting?infrastructure?is?present?in?any?of?several?MCU?based?keyer?designs?such?as?the?K3NG,?Morserino,?etc.
I?have?guests?coming?for?the?eclipse,?so?I?won't?have?time?to?bring?up?a?development?environment?to?compile?one?of?the?keyer?codes?so?I?can?implement?the?changes,?but?from?the?description,?it?should?be?clear?this?is?not?a?complex?algorithm.
Have?Fun!
Reg
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Re: Suppression of QRN via clock aligned Morse symbols
Good. That means I can piggyback on your work :).
Dave
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On Mar 23, 2024, at 13:17, Reginald Beardsley via groups.io <pulaskite@...> wrote:
? I've had to think about it for years to get to this point!
On Saturday, March 23, 2024 at 11:09:00 AM CDT, Dave Daniel <kc0wjn@...> wrote:
I have to think about this before rendering an opinion. Thanks. DaveD > On Mar 23, 2024, at 11:50, Reginald Beardsley via groups.io <pulaskite@...> wrote: > > ?I've been working on the general concept of a mashup of QRSS and CCW in earnest for the last few weeks and have an algorithm to present.? The algorithm implements a statistical non-linear operator which eliminates QRN from an incoming audio stream.? The output is a clean keyed audio tone. > > The Coherent CW concept goes back many years, but for various reasons has never become popular.? My hope is this will change that. > > The fundamental notion is that all Morse symbol edges sent by a station are aligned at one of several dit frame lengths.? 100, 75 & 50 ms for 12, 16 & 24 wpm for audio QSOs and then 1-10 s dit frames for QRSS message transfer. > > At startup on an unused frequency, the receiver listens for 10 seconds and calculates the mean value and standard deviation of the absolute amplitude to produce a statistical estimate for QRN. > > Once that has been done a signal is detected by testing the mean value of a dit frame to see if it exceeds a threshold of alpha*sigma + the mean value of the QRN.? If it does key a sidetone dit. > > For optimal performance, the clock timing at the receiving station needs to be synchronized to the incoming signal.? The initial sync is best done by using a Gold code dit stream.? Gold codes have the property that they have optimal correlation properties making determining propagation delays? more accurate. > > Once? a QSO has started, every Nth character that gets decoded gets a resync performed by FFT. > > Keying the transmitter requires buffering the start of a dit or dah by as much as one frame.? If the operator heard the latency while keying it would be very uncomfortable.? However, only the receiving station hears the latency and it doesn't affect them.? Sender hears normal sidetone and receiver hears the signal with at most a single dit frame delay added to the propagation delay. > > All of the requisite supporting infrastructure is present in any of several MCU based keyer designs such as the K3NG, Morserino, etc. > > I have guests coming for the eclipse, so I won't have time to bring up a development environment to compile one of the keyer codes so I can implement the changes, but from the description, it should be clear this is not a complex algorithm. > > Have Fun! > Reg > > > > >
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Re: Suppression of QRN via clock aligned Morse symbols
I've had to think about it for years to get to this point!
On Saturday, March 23, 2024 at 11:09:00 AM CDT, Dave Daniel <kc0wjn@...> wrote:
I have to think about this before rendering an opinion. Thanks. DaveD > On Mar 23, 2024, at 11:50, Reginald Beardsley via groups.io <pulaskite@...> wrote: > > ?I've been working on the general concept of a mashup of QRSS and CCW in earnest for the last few weeks and have an algorithm to present.? The algorithm implements a statistical non-linear operator which eliminates QRN from an incoming audio stream.? The output is a clean keyed audio tone. > > The Coherent CW concept goes back many years, but for various reasons has never become popular.? My hope is this will change that. > > The fundamental notion is that all Morse symbol edges sent by a station are aligned at one of several dit frame lengths.? 100, 75 & 50 ms for 12, 16 & 24 wpm for audio QSOs and then 1-10 s dit frames for QRSS message transfer. > > At startup on an unused frequency, the receiver listens for 10 seconds and calculates the mean value and standard deviation of the absolute amplitude to produce a statistical estimate for QRN. > > Once that has been done a signal is detected by testing the mean value of a dit frame to see if it exceeds a threshold of alpha*sigma + the mean value of the QRN.? If it does key a sidetone dit. > > For optimal performance, the clock timing at the receiving station needs to be synchronized to the incoming signal.? The initial sync is best done by using a Gold code dit stream.? Gold codes have the property that they have optimal correlation properties making determining propagation delays? more accurate. > > Once? a QSO has started, every Nth character that gets decoded gets a resync performed by FFT. > > Keying the transmitter requires buffering the start of a dit or dah by as much as one frame.? If the operator heard the latency while keying it would be very uncomfortable.? However, only the receiving station hears the latency and it doesn't affect them.? Sender hears normal sidetone and receiver hears the signal with at most a single dit frame delay added to the propagation delay. > > All of the requisite supporting infrastructure is present in any of several MCU based keyer designs such as the K3NG, Morserino, etc. > > I have guests coming for the eclipse, so I won't have time to bring up a development environment to compile one of the keyer codes so I can implement the changes, but from the description, it should be clear this is not a complex algorithm. > > Have Fun! > Reg > > > > >
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Re: Suppression of QRN via clock aligned Morse symbols
I have to think about this before rendering an opinion.
Thanks.
DaveD
toggle quoted message
Show quoted text
On Mar 23, 2024, at 11:50, Reginald Beardsley via groups.io <pulaskite@...> wrote:
?I've been working on the general concept of a mashup of QRSS and CCW in earnest for the last few weeks and have an algorithm to present. The algorithm implements a statistical non-linear operator which eliminates QRN from an incoming audio stream. The output is a clean keyed audio tone.
The Coherent CW concept goes back many years, but for various reasons has never become popular. My hope is this will change that.
The fundamental notion is that all Morse symbol edges sent by a station are aligned at one of several dit frame lengths. 100, 75 & 50 ms for 12, 16 & 24 wpm for audio QSOs and then 1-10 s dit frames for QRSS message transfer.
At startup on an unused frequency, the receiver listens for 10 seconds and calculates the mean value and standard deviation of the absolute amplitude to produce a statistical estimate for QRN.
Once that has been done a signal is detected by testing the mean value of a dit frame to see if it exceeds a threshold of alpha*sigma + the mean value of the QRN. If it does key a sidetone dit.
For optimal performance, the clock timing at the receiving station needs to be synchronized to the incoming signal. The initial sync is best done by using a Gold code dit stream. Gold codes have the property that they have optimal correlation properties making determining propagation delays more accurate.
Once a QSO has started, every Nth character that gets decoded gets a resync performed by FFT.
Keying the transmitter requires buffering the start of a dit or dah by as much as one frame. If the operator heard the latency while keying it would be very uncomfortable. However, only the receiving station hears the latency and it doesn't affect them. Sender hears normal sidetone and receiver hears the signal with at most a single dit frame delay added to the propagation delay.
All of the requisite supporting infrastructure is present in any of several MCU based keyer designs such as the K3NG, Morserino, etc.
I have guests coming for the eclipse, so I won't have time to bring up a development environment to compile one of the keyer codes so I can implement the changes, but from the description, it should be clear this is not a complex algorithm.
Have Fun!
Reg
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Suppression of QRN via clock aligned Morse symbols
I've?been?working?on?the?general?concept?of?a?mashup?of?QRSS?and?CCW?in?earnest?for?the?last?few?weeks?and?have?an?algorithm?to?present.??The?algorithm?implements?a?statistical?non-linear?operator?which?eliminates?QRN?from?an?incoming?audio?stream.??The?output?is?a?clean?keyed?audio?tone.
The?Coherent?CW?concept?goes?back?many?years,?but?for?various?reasons?has?never?become?popular.??My?hope?is?this?will?change?that.
The?fundamental?notion?is?that?all?Morse?symbol?edges?sent?by?a?station?are?aligned?at?one?of?several?dit?frame?lengths.??100,?75?&?50?ms?for?12,?16?&?24?wpm?for?audio?QSOs?and?then?1-10?s?dit?frames?for?QRSS?message?transfer.
At?startup?on?an?unused?frequency,?the?receiver?listens?for?10?seconds?and?calculates?the?mean?value?and?standard?deviation?of?the?absolute?amplitude?to?produce?a?statistical?estimate?for?QRN.
Once?that?has?been?done?a?signal?is?detected?by?testing?the?mean?value?of?a?dit?frame?to?see?if?it?exceeds?a?threshold?of?alpha*sigma?+?the?mean?value of the QRN.??If?it?does?key?a?sidetone?dit.
For?optimal?performance,?the?clock?timing?at?the?receiving?station?needs?to?be?synchronized?to?the?incoming?signal.??The?initial?sync?is?best?done?by?using?a?Gold?code?dit?stream.??Gold?codes?have?the?property?that?they?have?optimal?correlation?properties?making?determining?propagation?delays??more?accurate.
Once??a?QSO?has?started,?every?Nth?character?that?gets?decoded?gets?a?resync?performed?by?FFT.
Keying?the?transmitter?requires?buffering?the?start?of?a?dit?or?dah?by?as?much?as?one?frame.??If?the?operator?heard?the?latency?while?keying?it?would?be?very?uncomfortable.??However,?only?the?receiving?station?hears?the?latency?and?it?doesn't?affect?them.??Sender?hears?normal?sidetone?and?receiver?hears?the?signal?with?at?most?a?single?dit?frame?delay?added?to?the?propagation?delay.
All?of?the?requisite?supporting?infrastructure?is?present?in?any?of?several?MCU?based?keyer?designs?such?as?the?K3NG,?Morserino,?etc.
I?have?guests?coming?for?the?eclipse,?so?I?won't?have?time?to?bring?up?a?development?environment?to?compile?one?of?the?keyer?codes?so?I?can?implement?the?changes,?but?from?the?description,?it?should?be?clear?this?is?not?a?complex?algorithm.
Have?Fun!
Reg
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Daniel Ricardo Perez LW1ECP