Date   

Re: Serious question

 

Eric, 
I also use the KK7UQ meter, as well as the PSK Meter.
They're both useful.
Milt.
N6MG


-----Original Message-----
From: Eric KG6MZS <contact@...>
To: main@070Club.groups.io
Sent: Mon, Dec 28, 2020 8:11 am
Subject: Re: [070Club] Serious question

John,
I'm glad you joined the conversation because, like Jerry, I tend to disregard the IMD/s:n reports as mostly meaningless.  As I mentioned before, DM780 will generate a -30db IMD and a +32db s/n on dead air.  By your criteria below, that should be a good signal.
My understanding is that an accurate IMD/s:n measurement needs to be on "empty rails" or when no text is shifting the phase.  I'm pretty sure that the software is not being that discriminating when it snags the numbers.  I'm also pretty sure that the ops handing them out aren't painstakingly writing them down and sending them manually when they see empty rails and might be getting an accurate reading.
As you know, I rely on my KK7UQ to let me know what my IMD is.  From that perspective, FT-8's automated reports are much more meaningful.  They tell me how loud my signal is in another operator's waterfall relative to all the other signals they might be receiving.  The quality of my signal is already known to me via my own feedback from the IMD meter calibrated on PSK-31
Eric
On 12/28/20 7:33 AM, John - KC3FL via groups.io wrote:

One of my favorite subjects.  An RSQ is an arbitrary number that the op makes up.  Some give a meaningful RSQ but most give the 599.  S/N and IMD are real numbers that your software generates and tells all about the signal.  The IMD without the S/N is useless because if the S/N is 15 dB and the IMD is -15 dB, that is a great  signal, however if the S/N were 30 dB and the IMD was -15 dB, that is being over driven and probably is 2 or 3 hundred Hz wide.  The closer the IMD is to the negative value of the S/N, the cleaner the signal because all the harmonics are suppressed.  Unfortunately the software has a tough time getting the IMD right as you can tell as the IMD figure usually jumps around.


Re: RESULTS – DOUBLEHEADER LOW BAND SPRINT – 2020

DAVE KB3RAN 1692/381
 

I thought I came in 3rd place in Medium Power.  The QTH is correct but the name and callsign aren't mine. Not surprised that a typo crept in with all of the hand work done on these contests.

Dave
KB3RAN
1962/381


-----Original Message-----
From: stan W9SMR <robinstan@...>
To: main@070Club.groups.io
Sent: Mon, Dec 28, 2020 3:12 pm
Subject: [070Club] RESULTS – DOUBLEHEADER LOW BAND SPRINT – 2020

RESULTS – DOUBLEHEADER LOW BAND SPRINT – 2020
The excitement was high for this race because the winner of the Annual RC3 rested on who would win this contest. Neck and neck were leader John, KC3FL, and Lee, N5SLY, separated by only 5.91 points out of 900+ points. Not to spoil the surprise, but it looks to me like John will be our new RC3 2020 Award winner.

This year there were 49 logs submitted – up from last year’s 45 logs. There were 16 High Power, 16 Medium Power, 13 Low Power and four QRP logs submitted. There were a total of 1917 logged QSO’s; 1257 on 40M, 612 on 80M and 48 on 160M.

Top Dawg and 1st in High Power was John, KC3FL of Inverness, FL, with a record breaking 110 QSOs (7 on 160M) and 5476 points. Another stellar showing from John who seemed to be all over the bands.

High Power - Second Place was major player Lee, N5SLY, of Sherman, TX with 4340 points. Did the lack of a 160M antenna at Lee’s QTH make the difference? Third place was new member Darin, KO4EJD with 4320 points. Darin finished in 2nd place, High Power in the Triple Play.

Medium Power – First place was Stan, W9SMR of Sarasota, FL, with 2990 points. It’s amazing what one can do with a jury-rigged Inv-L strung through the neighbors’ palm trees.

Medium Power – Second place was new member Terry, KZ4KX of Austin, KY with 2737 points. Terry made a grand appearance in his first 070 contest as a member. Third Place went to Fred, KK4HEG, of Lusby, MD, with 2575 points.

Low Power – First place was Steve, W3HF, Collegeville, PA with 4140 points. Steve really kicked up a storm, nearly beating the High Power boys.

Low Power - Second Place went to new member Jeff, AC1JR with 1836 points. Jeff finished 1st Low Power in the Triple Play. Third Place went to Don, KM4UDX of Vienna, VA with 1680 points.

QRP Power First Place went to WS8G of Beavercreek, OH with 63 QSOs and 2184 points. That’s a great achievement on these low bands these days.

QRP Power – Second Place went to Rick, N7WE of Leesburg, FL with 41 QSO’s and 1173 points. Third Place went to Steve, VA3FLF of Fort Erie, ON with 26 QSOs and 392 points.
 


The new “All Amateurs Welcome” policy continues to enhance our overall experience. We had 2 non-members submit logs. We hope to see applications from AA8SW and NN9C soon!
Note that the Top Dawg Certificate and Rollo Dog Tag will be reserved exclusively for members.

Thanks to all who submitted logs. Stickers will be in the next mailing.  Complete results as manually calculated by David, K9DWR, will be uploaded to the Groups.io site under FILES/CONTEST RESULTS.

It is time to start thinking about your participation in the next PODXS 070 Event.
 
The Ø7Ø Club PSKfest is less than 1 week away -

  0000Z Saturday 2 January 2021 to 2359Z Saturday 2 January 2021
 
This is a 1 day event – Friday evening and Saturday in US.

Open to all licensed radio amateurs. Using 80M thru 10M (No WARC Bands)

For Rules and detailsClick Here: PSKFest Rules


 
73,
Stan
W9SMR - 070  #1611
PODXS 070 - PR Director

--
Dave H KB3RAN 1692/381


Re: Serious question

David, K9DWR
 

On Dec 28, 2020, at 14:48, N6MG - Milt. via groups.io <n6mg=verizon.net@groups.io> wrote:

John, may I ask?, What software is that?
That’s fldigi (you can see the name in the title bar if you look closely)



David, K9DWR
#1604 LONP #255
david@graniteweb.com


Re: Serious question

 

John, may I ask?, What software is that?
Milt
N6MG

-----Original Message-----
From: John - KC3FL via groups.io <kc3fl@...>
To: main@070Club.groups.io
Sent: Mon, Dec 28, 2020 7:44 am
Subject: Re: [070Club] Serious question

Finally figured out how to attach a picture so here is a good visual explanation of IMD

John
KC3FL

Attachments:


Re: RESULTS – DOUBLEHEADER LOW BAND SPRINT – 2020

Leland Sly
 

Congrats John, KC3FL...well done!

73

Lee N5SLY

On Mon, Dec 28, 2020 at 2:12 PM stan W9SMR <robinstan@...> wrote:

RESULTS – DOUBLEHEADER LOW BAND SPRINT – 2020

The excitement was high for this race because the winner of the Annual RC3 rested on who would win this contest. Neck and neck were leader John, KC3FL, and Lee, N5SLY, separated by only 5.91 points out of 900+ points. Not to spoil the surprise, but it looks to me like John will be our new RC3 2020 Award winner.

This year there were 49 logs submitted – up from last year’s 45 logs. There were 16 High Power, 16 Medium Power, 13 Low Power and four QRP logs submitted. There were a total of 1917 logged QSO’s; 1257 on 40M, 612 on 80M and 48 on 160M.

Top Dawg and 1st in High Power was John, KC3FL of Inverness, FL, with a record breaking 110 QSOs (7 on 160M) and 5476 points. Another stellar showing from John who seemed to be all over the bands.

High Power - Second Place was major player Lee, N5SLY, of Sherman, TX with 4340 points. Did the lack of a 160M antenna at Lee’s QTH make the difference? Third place was new member Darin, KO4EJD with 4320 points. Darin finished in 2nd place, High Power in the Triple Play.

Medium Power – First place was Stan, W9SMR of Sarasota, FL, with 2990 points. It’s amazing what one can do with a jury-rigged Inv-L strung through the neighbors’ palm trees.

Medium Power – Second place was new member Terry, KZ4KX of Austin, KY with 2737 points. Terry made a grand appearance in his first 070 contest as a member. Third Place went to Fred, KK4HEG, of Lusby, MD, with 2575 points.

Low Power – First place was Steve, W3HF, Collegeville, PA with 4140 points. Steve really kicked up a storm, nearly beating the High Power boys.

Low Power - Second Place went to new member Jeff, AC1JR with 1836 points. Jeff finished 1st Low Power in the Triple Play. Third Place went to Don, KM4UDX of Vienna, VA with 1680 points.

QRP Power First Place went to WS8G of Beavercreek, OH with 63 QSOs and 2184 points. That’s a great achievement on these low bands these days.

QRP Power – Second Place went to Rick, N7WE of Leesburg, FL with 41 QSO’s and 1173 points. Third Place went to Steve, VA3FLF of Fort Erie, ON with 26 QSOs and 392 points.

 



The new “All Amateurs Welcome” policy continues to enhance our overall experience. We had 2 non-members submit logs. We hope to see applications from AA8SW and NN9C soon!

Note that the Top Dawg Certificate and Rollo Dog Tag will be reserved exclusively for members.

Thanks to all who submitted logs. Stickers will be in the next mailing.  Complete results as manually calculated by David, K9DWR, will be uploaded to the Groups.io site under FILES/CONTEST RESULTS.

It is time to start thinking about your participation in the next PODXS 070 Event.

 

The Ø7Ø Club PSKfest is less than 1 week away -

  0000Z Saturday 2 January 2021 to 2359Z Saturday 2 January 2021

 

This is a 1 day event – Friday evening and Saturday in US.

Open to all licensed radio amateurs. Using 80M thru 10M (No WARC Bands)

For Rules and detailsClick Here: PSKFest Rules


 

73,

Stan
W9SMR - 070  #1611
PODXS 070 - PR Director


RESULTS – DOUBLEHEADER LOW BAND SPRINT – 2020

stan W9SMR
 

RESULTS – DOUBLEHEADER LOW BAND SPRINT – 2020

The excitement was high for this race because the winner of the Annual RC3 rested on who would win this contest. Neck and neck were leader John, KC3FL, and Lee, N5SLY, separated by only 5.91 points out of 900+ points. Not to spoil the surprise, but it looks to me like John will be our new RC3 2020 Award winner.

This year there were 49 logs submitted – up from last year’s 45 logs. There were 16 High Power, 16 Medium Power, 13 Low Power and four QRP logs submitted. There were a total of 1917 logged QSO’s; 1257 on 40M, 612 on 80M and 48 on 160M.

Top Dawg and 1st in High Power was John, KC3FL of Inverness, FL, with a record breaking 110 QSOs (7 on 160M) and 5476 points. Another stellar showing from John who seemed to be all over the bands.

High Power - Second Place was major player Lee, N5SLY, of Sherman, TX with 4340 points. Did the lack of a 160M antenna at Lee’s QTH make the difference? Third place was new member Darin, KO4EJD with 4320 points. Darin finished in 2nd place, High Power in the Triple Play.

Medium Power – First place was Stan, W9SMR of Sarasota, FL, with 2990 points. It’s amazing what one can do with a jury-rigged Inv-L strung through the neighbors’ palm trees.

Medium Power – Second place was new member Terry, KZ4KX of Austin, KY with 2737 points. Terry made a grand appearance in his first 070 contest as a member. Third Place went to Fred, KK4HEG, of Lusby, MD, with 2575 points.

Low Power – First place was Steve, W3HF, Collegeville, PA with 4140 points. Steve really kicked up a storm, nearly beating the High Power boys.

Low Power - Second Place went to new member Jeff, AC1JR with 1836 points. Jeff finished 1st Low Power in the Triple Play. Third Place went to Don, KM4UDX of Vienna, VA with 1680 points.

QRP Power First Place went to WS8G of Beavercreek, OH with 63 QSOs and 2184 points. That’s a great achievement on these low bands these days.

QRP Power – Second Place went to Rick, N7WE of Leesburg, FL with 41 QSO’s and 1173 points. Third Place went to Steve, VA3FLF of Fort Erie, ON with 26 QSOs and 392 points.

 



The new “All Amateurs Welcome” policy continues to enhance our overall experience. We had 2 non-members submit logs. We hope to see applications from AA8SW and NN9C soon!

Note that the Top Dawg Certificate and Rollo Dog Tag will be reserved exclusively for members.

Thanks to all who submitted logs. Stickers will be in the next mailing.  Complete results as manually calculated by David, K9DWR, will be uploaded to the Groups.io site under FILES/CONTEST RESULTS.

It is time to start thinking about your participation in the next PODXS 070 Event.

 

The Ø7Ø Club PSKfest is less than 1 week away -

  0000Z Saturday 2 January 2021 to 2359Z Saturday 2 January 2021

 

This is a 1 day event – Friday evening and Saturday in US.

Open to all licensed radio amateurs. Using 80M thru 10M (No WARC Bands)

For Rules and detailsClick Here: PSKFest Rules


 

73,

Stan
W9SMR - 070  #1611
PODXS 070 - PR Director


Re: 25 contacts on 20m

Eric KG6MZS
 


On 12/28/20 11:19 AM, N6MG - Milt. via groups.io wrote:

Milt.
N6MG


Milt, I just realized that your call might be extremely valuable to one of us SOTA guys.  ;-)




Re: 25 contacts on 20m

 

Steve,
Thanks for posting the callsign's of the stations that have submitted logs thus far.
For my "post-operating-event-log-analysis", it's of value to see who was actually on, vs who I was able to work & get in my log.
I look forward to seeing the full list when that happens.
73,
Milt.
N6MG
070-650


-----Original Message-----
From: Stephen Melachrinos via groups.io <melachri@...>
To: main@070Club.groups.io <main@070Club.groups.io>
Sent: Mon, Dec 28, 2020 4:07 am
Subject: Re: [070Club] 25 contacts on 20m

Pat -

I have your log and it is good.

So far I have received qualifying logs from the following:

AC1JR
AG4QX
EB3JT
K3ALB
K3YES
K4VBM
K5SP
KA5VZG
KB3RAN
KC3FL
KC4OBB
KD9DVB
KE4PWE
KK6KMU
KO4EJD
KR4U
N5SLY
N6MG
N6PCD
N7WE
N9AVY
NN9K
ON2AD
W0JSL
W3HF
WA3WZR

I also received emails logs from a few stations who did not make 25 QSOs but wanted to say that they participated.

Thank you for the efforts in making the logs readable and usable for manual processing. And keep them coming!

Steve
W3HF


-----Original Message-----
From: ON2AD Pat <ON2AD.Pat@...>
To: main@070Club.groups.io
Sent: Mon, Dec 28, 2020 5:18 am
Subject: Re: [070Club] 25 contacts on 20m

I started 25 Dec 2020 at 08:37 to 19:18 UTC.
Worked:
20M and 40M band
results (very poor for a day):
34 QSOs
17 DXCCs
04 Continents - AF - AS - EU -NA
07 WAZ
09 ITU
29 WPX

I worked only one USA station, the conditions on that day were weak and there was a lot of QSB on some signals.

I hope my log is received

I wish everyone a Happy New Year in good health

73 de Pat ON2AD (PODX070-703)


Re: Serious question

Jerry N9AVY
 

Often copy signals all bunched together like a DX pileup.  Never understand why ops don't spread out a bit....

Jerry, n9avy

, On Monday, December 28, 2020, 10:33:29 AM CST, Eric KG6MZS <contact@...> wrote:


Now that's interesting.  I didn't know that, but it makes sense.  Thanks Stephen.  Learn something new every day.

On 12/28/20 8:14 AM, Stephen Melachrinos via groups.io wrote:
- If there is another signal right next to the signal you are copying (like 50 Hz away), your software will measure its power and attribute that to IMD.


Re: Serious question

Bob Motyl KK6KMU
 

John,

Thank you for your S/N and IMD post.  Greatly appreciated.  As  amateur radio operators we have a responsibility to minimize any unnecessary noise that is transmitted by our station.  If the audio levels that are going into your transmitter are too high the rigs output amplifier is driven into its nonlinear region and creates higher order harmonics (noise).  Most PSK operators have their levels properly adjusted.  Occasionally I do see someone with too much audio input, and politely recommend they reduce it.  I appreciate knowing how my station is performing.  Keep the S/N and IMD reports coming.

Bob KK6KMU


Re: Serious question

 

Like I said, the software has a hard time displaying the correct IMD because close by signals can mess it up and the only way the software can get an accurate reading is with an idle signal.  So it is only useful if the software catches the signal at some point where there are no characters being sent and the signal is in the clear, that's why I depend on my KK7UQ IMD meter.  If I see that the computer got it wrong, I'll send it again when I see that it is correct.  I pay more attention to the S/N and adjust my power accordingly, I already know my IMD.  Guess it's just a personal choice.

John
KC3FL


Re: Serious question

Eric KG6MZS
 

Now that's interesting.  I didn't know that, but it makes sense.  Thanks Stephen.  Learn something new every day.

On 12/28/20 8:14 AM, Stephen Melachrinos via groups.io wrote:
- If there is another signal right next to the signal you are copying (like 50 Hz away), your software will measure its power and attribute that to IMD.


Re: Serious question

Stephen Melachrinos
 

John -

You are right--RST/RSQ are subjective, and S/N and IMD are measured. But the problem is that it's not always clear what is being measured. Both are based on power measurements, but the software can't really tell the difference between true noise power and another signal--they are just measuring noise within a particular bandwidth, and only of the signal as presented as audio to the software. Here are some places where that could be a problem.

- If there is another signal right next to the signal you are copying (like 50 Hz away), your software will measure its power and attribute that to IMD.
- We usually think of S/N in terms of background noise (true QRN), but in a very crowded band the software will measure the composite signal power of all the other signals within its measurement bandwidth.
- Because the software only looks at the audio signal (after the "downconversion" performed by your SSB demod), it can't tell the difference between distortions in the other station's transmitter and ones created in your receiver.

Now in a very quiet band (low noise and few other signals), the software has an easy job, and the numbers are meaningful. The pictures you posted are examples of that. But some folks use macros that automatically extract the S/N and IMD and send it to everyone all the time. Since I can't tell what that station's waterfall looks like, I typically ignore those numbers because I don't have confidence that they are being measured accurately or appropriately.

The bottom line is that sometimes S/N and IMD are significant, but IMO it's usually too hard to figure out whether it's one of those times (unless I know the other station well). 

Steve
W3HF


-----Original Message-----
From: John - KC3FL via groups.io <kc3fl@...>
To: main@070Club.groups.io
Sent: Mon, Dec 28, 2020 10:33 am
Subject: Re: [070Club] Serious question

One of my favorite subjects.  An RSQ is an arbitrary number that the op makes up.  Some give a meaningful RSQ but most give the 599.  S/N and IMD are real numbers that your software generates and tells all about the signal.  The IMD without the S/N is useless because if the S/N is 15 dB and the IMD is -15 dB, that is a great  signal, however if the S/N were 30 dB and the IMD was -15 dB, that is being over driven and probably is 2 or 3 hundred Hz wide.  The closer the IMD is to the negative value of the S/N, the cleaner the signal because all the harmonics are suppressed.  Unfortunately the software has a tough time getting the IMD right as you can tell as the IMD figure usually jumps around.


Re: Serious question

Eric KG6MZS
 

John,

I'm glad you joined the conversation because, like Jerry, I tend to disregard the IMD/s:n reports as mostly meaningless.  As I mentioned before, DM780 will generate a -30db IMD and a +32db s/n on dead air.  By your criteria below, that should be a good signal.

My understanding is that an accurate IMD/s:n measurement needs to be on "empty rails" or when no text is shifting the phase.  I'm pretty sure that the software is not being that discriminating when it snags the numbers.  I'm also pretty sure that the ops handing them out aren't painstakingly writing them down and sending them manually when they see empty rails and might be getting an accurate reading.

As you know, I rely on my KK7UQ to let me know what my IMD is.  From that perspective, FT-8's automated reports are much more meaningful.  They tell me how loud my signal is in another operator's waterfall relative to all the other signals they might be receiving.  The quality of my signal is already known to me via my own feedback from the IMD meter calibrated on PSK-31

Eric

On 12/28/20 7:33 AM, John - KC3FL via groups.io wrote:

One of my favorite subjects.  An RSQ is an arbitrary number that the op makes up.  Some give a meaningful RSQ but most give the 599.  S/N and IMD are real numbers that your software generates and tells all about the signal.  The IMD without the S/N is useless because if the S/N is 15 dB and the IMD is -15 dB, that is a great  signal, however if the S/N were 30 dB and the IMD was -15 dB, that is being over driven and probably is 2 or 3 hundred Hz wide.  The closer the IMD is to the negative value of the S/N, the cleaner the signal because all the harmonics are suppressed.  Unfortunately the software has a tough time getting the IMD right as you can tell as the IMD figure usually jumps around.


Re: Serious question

Stephen Melachrinos
 

I usually quote a signal quality "at the peaks" and then say there's QSB.

Steve
W3HF


-----Original Message-----
From: DAVE KB3RAN 1692/381 via groups.io <davehardy0101@...>
To: n9avy@... <n9avy@...>; main@070Club.groups.io <main@070Club.groups.io>
Sent: Mon, Dec 28, 2020 10:46 am
Subject: Re: [070Club] Serious question

Does a 599 count when the overall signal is really good but qsb garbles the message?  I need to review what constitutes the RST values again.

Dave
KB3RAN
1692/381
APE Event Mgr


-----Original Message-----
From: Jerry N9AVY <n9avy@...>
To: main@070Club.groups.io <main@070Club.groups.io>
Sent: Mon, Dec 28, 2020 10:40 am
Subject: Re: [070Club] Serious question

Love it when a station gives me a 599 and keeps asking for fill....  Emoji

Jerry  n9avy

On Monday, December 28, 2020, 09:33:23 AM CST, John - KC3FL via groups.io <kc3fl@...> wrote:


One of my favorite subjects.  An RSQ is an arbitrary number that the op makes up.  Some give a meaningful RSQ but most give the 599.  S/N and IMD are real numbers that your software generates and tells all about the signal.  The IMD without the S/N is useless because if the S/N is 15 dB and the IMD is -15 dB, that is a great  signal, however if the S/N were 30 dB and the IMD was -15 dB, that is being over driven and probably is 2 or 3 hundred Hz wide.  The closer the IMD is to the negative value of the S/N, the cleaner the signal because all the harmonics are suppressed.  Unfortunately the software has a tough time getting the IMD right as you can tell as the IMD figure usually jumps around.


--
Dave H KB3RAN 1692/381


Re: 2020 Contest Certificates

Stephen Melachrinos
 

Jim - 

That was a big job. Thank you for all your effort for the club.

73,
Steve
W3HF


-----Original Message-----
From: Jim K5SP <jinnis@...>
To: main@070Club.groups.io
Sent: Mon, Dec 28, 2020 10:51 am
Subject: [070Club] 2020 Contest Certificates

All certificates for the PODXS070 contests conducted during 2020 have been sent by email to the award recipients except for DoubleHeader (awaiting final results), and the Top Dawg awards (will be mailed with keychain).

If you did not receive a certificate you were expecting, or if your certificate is incorrect in any way, contact me and I will investigate and make corrections.

In the future, we will email certificates soon after the close of the contest, waiting until end of year as has been done in the past creates an unbelievable workload.

73, and Congratulations to the recipients.
--
Jim,  K5SP #483
Executive Director/Member Services Director


2020 Contest Certificates

Jim K5SP
 

All certificates for the PODXS070 contests conducted during 2020 have been sent by email to the award recipients except for DoubleHeader (awaiting final results), and the Top Dawg awards (will be mailed with keychain).

If you did not receive a certificate you were expecting, or if your certificate is incorrect in any way, contact me and I will investigate and make corrections.

In the future, we will email certificates soon after the close of the contest, waiting until end of year as has been done in the past creates an unbelievable workload.

73, and Congratulations to the recipients.
--
Jim,  K5SP #483
Executive Director/Member Services Director


Re: Serious question

Jerry N9AVY
 

John:

As far as I can see there is no S/N generated or available on MixW 3.2.   

Jerry

On Monday, December 28, 2020, 09:44:44 AM CST, John - KC3FL via groups.io <kc3fl@...> wrote:


Finally figured out how to attach a picture so here is a good visual explanation of IMD

John
KC3FL

Attachments:


Re: Serious question

DAVE KB3RAN 1692/381
 

Does a 599 count when the overall signal is really good but qsb garbles the message?  I need to review what constitutes the RST values again.

Dave
KB3RAN
1692/381
APE Event Mgr


-----Original Message-----
From: Jerry N9AVY <n9avy@...>
To: main@070Club.groups.io <main@070Club.groups.io>
Sent: Mon, Dec 28, 2020 10:40 am
Subject: Re: [070Club] Serious question

Love it when a station gives me a 599 and keeps asking for fill....  Emoji

Jerry  n9avy

On Monday, December 28, 2020, 09:33:23 AM CST, John - KC3FL via groups.io <kc3fl@...> wrote:


One of my favorite subjects.  An RSQ is an arbitrary number that the op makes up.  Some give a meaningful RSQ but most give the 599.  S/N and IMD are real numbers that your software generates and tells all about the signal.  The IMD without the S/N is useless because if the S/N is 15 dB and the IMD is -15 dB, that is a great  signal, however if the S/N were 30 dB and the IMD was -15 dB, that is being over driven and probably is 2 or 3 hundred Hz wide.  The closer the IMD is to the negative value of the S/N, the cleaner the signal because all the harmonics are suppressed.  Unfortunately the software has a tough time getting the IMD right as you can tell as the IMD figure usually jumps around.


--
Dave H KB3RAN 1692/381


Re: Serious question

 

Finally figured out how to attach a picture so here is a good visual explanation of IMD

John
KC3FL

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