Re: [Elecraft] New K3 Firmware: Pileup-inspired AGC changes
Jan Erik Holm wrote: Don Rasmussen wrote: Anyone care to take a guess as to how long an anomoly like this would live in any other mass produced HF transceiver? My guess - the life of the radio. Maybe the Flex guys would get to it. With Elecraft, the issue was identified on the weekend, and here it is Wednesday of the same week, the engineers understand the effect and offer test software for it. Kudos! Indeed! Just one example. As I understand this problem the Yaesu FT-1000MP suffers from the same (lets call it) AGC IMD. On the MP I have noticed it myself and others too but it is not widely written about. Very glad to see that it possibly can be fixed on the K3. 73 Jim SM2EKM Like everything else about the nasty key-click generator FT-1000MP, it's left to the customer to find and fix any problems. Yaesu did nothing about the key clicks for at least 13 years (beginning with FT-1000D until a production change for the MP in 2003)...and Yaesu is now reliving design problems with the roofing filters in the FT-2000. BTW Inrad did implement fixes for both the MP's clicks and the AGC problem (the customer must pay for all Yaesu design errors, of course): FT-1000MP AGC Improvement Mod Some operators on major DX-peditions have complained about poor readability in large pile ups. From a joint effort between Inrad and some of these operators, we are now offering the AGC mod which improves readability somewhat for both CW and SSB. Details of the history is included in the mod instruction sheets. This new mod increases the decay time, which in the FT-1000MP is so fast that weaker signals can come up to full output between dots and dashes (or speech peaks), causing poor readability in pile ups. It also uses a damping resistor to eliminate a slight over shoot. Please be aware that under normal or average operating conditions, this mod will make very little discernible difference. The AGC mod is not applicable to the Mark V. http://www.inrad.net/product.php?productid=86cat=10page=1 What a horrible contrast Yaesu was to my very pleasant experience with Elecraft! 73, Bill -- View this message in context: http://n2.nabble.com/New-K3-Firmware%3A-Pileup-inspired-AGC-changes-tp2387110p2389115.html Sent from the Elecraft mailing list archive at Nabble.com. __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [Elecraft] New K3 Firmware: Pileup-inspired AGC changes
--- On Wed, 2/25/09, Jim Brown j...@audiosystemsgroup.com wrote: Someone just posted that they had trouble in pileups during the contest last weekend, but the radio worked better when they turned on the attenuator and turned down the RF gain. DUH! I learned that in 1957 -- but younger operators never learned it, since modern radios depend so heavily on AGC. Nothing personal Jim, but your post is a handy one to add to. I've been licensed for over 50 years so I've been through all of the turn off the AVC (dating myself) and ride the rf gain control business. But I must say that having to turn off the AGC and ride the rf gain control in a modern whiz-bang super-duper multi-kilobuck radio seems oxymoronic to me. Why should I have to ride the gain? I thought all of this DSP stuff was supposed to be smarter than I am. Shouldn’t the radio be smart enough to know when a signal is so strong that the attenuator needs to be inserted to protect the DSP or the second mixer, for example? Besides the K3 AGC appears to never be off despite what the display reports. For example while listening to a strong AM broadcast station, if I reduce the RF Gain* with the AGC on so that the S-meter stops peaking# and adjust the audio gain for comfortable listening and then turn the ACG off, the signal practically disappears. If the AGC was truly off then there shouldn't be any change. Adjusting the RF Gain higher to bring back the signal level will also result in the S-meter following the signal peaks. Running this experiment also seems to demonstrate a problem with the gain distribution in this radio. If I reduce the RF Gain to the point that the S-meter is just beginning to be affected, there is a distinct reduction in the SNR. It's quite disconcerting to have a S9+50 dB, interference-free signal that sounds noisy. Comparing to my TS870 with the same signal, I can decrease the gain (increase the S–meter reading) by at least 20 dB without noticing any reduction in SNR. * RF Gain seems to be a misnomer; unless I'm mistaken (always a possibility) there isn't a gain-controlled RF amplifier in the radio. The only hardware that is obviously gain-controlled is the second stage in the first i-f amplifier. # I'm seeing 5 to 6 dB of increase in meter reading between no modulation and modulation peaks. I guess I'm old fashioned but I thought that the AM carrier strength should set the AGC level. This peak-reading AGC may also be a contributor to the distorted audio that has been widely reported. Wes Stewart, N7WS __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [Elecraft] New K3 Firmware: Pileup-inspired AGC changes
# I'm seeing 5 to 6 dB of increase in meter reading between no modulation and modulation peaks. I guess I'm old fashioned but I thought that the AM carrier strength should set the AGC level. It seems to me that this is exactly what one would expect. AM PEP = 4 x carrier (e.g. 6 dB). If an S-meter did not respond to peaks but rather responded to the no modulation signal level, it would be completely useless for CW or SSB. 73, ... Joe, W4TV -Original Message- From: elecraft-boun...@mailman.qth.net [mailto:elecraft-boun...@mailman.qth.net] On Behalf Of Wes Stewart Sent: Thursday, February 26, 2009 10:32 AM To: elecraft@mailman.qth.net; Jim Brown Subject: Re: [Elecraft] New K3 Firmware: Pileup-inspired AGC changes --- On Wed, 2/25/09, Jim Brown j...@audiosystemsgroup.com wrote: Someone just posted that they had trouble in pileups during the contest last weekend, but the radio worked better when they turned on the attenuator and turned down the RF gain. DUH! I learned that in 1957 -- but younger operators never learned it, since modern radios depend so heavily on AGC. Nothing personal Jim, but your post is a handy one to add to. I've been licensed for over 50 years so I've been through all of the turn off the AVC (dating myself) and ride the rf gain control business. But I must say that having to turn off the AGC and ride the rf gain control in a modern whiz-bang super-duper multi-kilobuck radio seems oxymoronic to me. Why should I have to ride the gain? I thought all of this DSP stuff was supposed to be smarter than I am. Shouldn’t the radio be smart enough to know when a signal is so strong that the attenuator needs to be inserted to protect the DSP or the second mixer, for example? Besides the K3 AGC appears to never be off despite what the display reports. For example while listening to a strong AM broadcast station, if I reduce the RF Gain* with the AGC on so that the S-meter stops peaking# and adjust the audio gain for comfortable listening and then turn the ACG off, the signal practically disappears. If the AGC was truly off then there shouldn't be any change. Adjusting the RF Gain higher to bring back the signal level will also result in the S-meter following the signal peaks. Running this experiment also seems to demonstrate a problem with the gain distribution in this radio. If I reduce the RF Gain to the point that the S-meter is just beginning to be affected, there is a distinct reduction in the SNR. It's quite disconcerting to have a S9+50 dB, interference-free signal that sounds noisy. Comparing to my TS870 with the same signal, I can decrease the gain (increase the S–meter reading) by at least 20 dB without noticing any reduction in SNR. * RF Gain seems to be a misnomer; unless I'm mistaken (always a possibility) there isn't a gain-controlled RF amplifier in the radio. The only hardware that is obviously gain-controlled is the second stage in the first i-f amplifier. # I'm seeing 5 to 6 dB of increase in meter reading between no modulation and modulation peaks. I guess I'm old fashioned but I thought that the AM carrier strength should set the AGC level. This peak-reading AGC may also be a contributor to the distorted audio that has been widely reported. Wes Stewart, N7WS __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [Elecraft] New K3 Firmware: Pileup-inspired AGC changes
I did that FT-1000MP mod and the improvement was marginal. It didn't correct the problem of AGC mush in the passband with big pileups. Lots of IMD in big contests with that radio, too. 73, Dick WC1M -Original Message- From: Bill W4ZV [mailto:btipp...@alum.mit.edu] Sent: Thursday, February 26, 2009 6:32 AM To: elecraft@mailman.qth.net Subject: Re: [Elecraft] New K3 Firmware: Pileup-inspired AGC changes Jan Erik Holm wrote: Don Rasmussen wrote: Anyone care to take a guess as to how long an anomoly like this would live in any other mass produced HF transceiver? My guess - the life of the radio. Maybe the Flex guys would get to it. With Elecraft, the issue was identified on the weekend, and here it is Wednesday of the same week, the engineers understand the effect and offer test software for it. Kudos! Indeed! Just one example. As I understand this problem the Yaesu FT-1000MP suffers from the same (lets call it) AGC IMD. On the MP I have noticed it myself and others too but it is not widely written about. Very glad to see that it possibly can be fixed on the K3. 73 Jim SM2EKM Like everything else about the nasty key-click generator FT-1000MP, it's left to the customer to find and fix any problems. Yaesu did nothing about the key clicks for at least 13 years (beginning with FT-1000D until a production change for the MP in 2003)...and Yaesu is now reliving design problems with the roofing filters in the FT-2000. BTW Inrad did implement fixes for both the MP's clicks and the AGC problem (the customer must pay for all Yaesu design errors, of course): FT-1000MP AGC Improvement Mod Some operators on major DX-peditions have complained about poor readability in large pile ups. From a joint effort between Inrad and some of these operators, we are now offering the AGC mod which improves readability somewhat for both CW and SSB. Details of the history is included in the mod instruction sheets. This new mod increases the decay time, which in the FT-1000MP is so fast that weaker signals can come up to full output between dots and dashes (or speech peaks), causing poor readability in pile ups. It also uses a damping resistor to eliminate a slight over shoot. Please be aware that under normal or average operating conditions, this mod will make very little discernible difference. The AGC mod is not applicable to the Mark V. http://www.inrad.net/product.php?productid=86cat=10page=1 What a horrible contrast Yaesu was to my very pleasant experience with Elecraft! 73, Bill -- View this message in context: http://n2.nabble.com/New-K3-Firmware%3A- Pileup-inspired-AGC-changes-tp2387110p2389115.html Sent from the Elecraft mailing list archive at Nabble.com. __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
[Elecraft] New K3 Firmware: Pileup-inspired AGC changes
There's been a lot of discussion recently about what happens to multiple closely spaced signals with AGC turned on. We have a new field-test firmware revision available that offers a significant improvement in such situations by reducing the IMD caused by conventional AGC. If you'd like to try it, please send an email to n...@elecraft.com. Details: Some operators described a merging of multiple, close-spaced signals when listening to pileups, making individual signals hard to copy. Assuming that a narrow crystal filter is in use (close to the DSP bandwidth), this is not desense. In most cases, we've discovered, the cause is IMD (intermodulation distortion) related to the AGC algorithm. To simulate what happens under pileup conditions, we combined four crystal oscillators with gaps between them of 5, 6, and 7 Hz (a total spread of 18 Hz for the four signals). We then injected the signals into the K3 at an equal level of about S5 and used spectral analysis to examine what happens to the passband. With AGC-F turned on (AGC fast, set to the K3's factory defaults), IMD products came up some 20-25 dB as compared to AGC OFF. The situation could be far worse in an actual on-air situation with more signals, noise, and key clicks. (AGC-S makes only a small improvement.) We ran the same test on several other radios, and verified the AGC-induced IMD characteristics are similar. IMD is generated because AGC can cause mixing between the tones and their harmonics. The faster the decay rate, in general, the more products will be generated. With just one or two signals, most products will be outside the DSP's narrow IF or AF passband. But in a pileup, where signals are greater in number and can be nearly on top of each other, there are many more opportunities for signals to combine. This results in IMD products spaced at 1 to 20 Hz, depending on the time constants, location of the signals, etc. Turning AGC off is one strategy that operators have traditionally used to combat the effects of AGC modulation. It then becomes necessary to ride the gain controls. Neither Lyle nor I have that much patience :) So we took a different approach: keep the AGC on, but reduce its modulation effects to negligible levels by adding a very long hold time. In the field-test firmware, two changes have been made. First, the AGC HLD menu setting, which used to apply only to voice modes, now applies to CW as well. (It still only affects AGC-S, the slow AGC setting.) Second, we increased the range of AGC HLD to facilitate experimentation. What we found is that an AGC hold time of about 1 second, combined with a slower AGC-S decay time, reduces in-band IMD with closely spaced signals by 20-25 dB, making it very similar to turning AGC off. The *attack* time is unaffected, so there is no thumping as you might have with audio-derived AGC. Any new signal peak above the one that starts the hold timer will restart the timer. This hold AGC appears to be useful in many listening situations. It can make voice signals sound cleaner, as well; after all, a voice signal can have many components, and AGC-induced modulation can add IMD products. It also helps with noisy band conditions. The down side to AGC hold is that large signals can charge it up to a high level, reducing gain for the duration of the hold time. But in many cases this is far preferable to the AGC IMD effects, especially if you're listening to many signals at similar amplitudes -- as in a pileup. 73, Wayne, N6KR Lyle, KK7P --- http://www.elecraft.com __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [Elecraft] New K3 Firmware: Pileup-inspired AGC changes
Wed Feb 25 13:45:20 EST 2009 wayne burdick n6kr wrote ... ... We have a new field-test firmware revision available that offers a significant improvement in such situations by reducing the IMD caused by conventional AGC. -- Wayne, I just received #2724 yesterday and am still inventorying the parts, and you've already improved mine and all existing and future K3s? And all that's necessary is to download and install new firmware? And there's no additional cost to the user? :) 73, Gary KI4GGX P.S. Does this new firmware eliminate the need for really narrow roofing filters? Does it make them even more useful? Does it not have any bearing? __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [Elecraft] New K3 Firmware: Pileup-inspired AGC changes
We now have plenty of volunteers to try this experimental AGC firmware. Thanks! 73, Wayne N6KR __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [Elecraft] New K3 Firmware: Pileup-inspired AGC changes
To those of you who are testing this: Remember that AGC HLD only affects slow AGC (AGC-S). So, once you have a long AGC HLD time set up (0.3 to 1 sec, let's say), you can go back and forth between fast AGC (with no hold), and slow AGC (with a long hold) just by tapping the AGC switch. Long-hold/slow AGC isn't going to be the best choice every situation. Some experimentation will be required. Please let me know what settings you're using, and what you've listened to (pileups, general QRM, QRN, voice signals, etc.). tnx Wayne N6KR --- http://www.elecraft.com __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
[Elecraft] New K3 Firmware: Pileup-inspired AGC changes
Anyone care to take a guess as to how long an anomoly like this would live in any other mass produced HF transceiver? My guess - the life of the radio. Maybe the Flex guys would get to it. With Elecraft, the issue was identified on the weekend, and here it is Wednesday of the same week, the engineers understand the effect and offer test software for it. Kudos! [Elecraft] New K3 Firmware: Pileup-inspired AGC changes wayne burdick n6kr at elecraft.com Wed Feb 25 13:45:20 EST 2009 There's been a lot of discussion recently about what happens to multiple closely spaced signals with AGC turned on. We have a new field-test firmware revision available that offers a significant improvement in such situations by reducing the IMD caused by conventional AGC. If you'd like to try it, please send an email to n6kr at elecraft.com. Details: Some operators described a merging of multiple, close-spaced signals when listening to pileups, making individual signals hard to copy. Assuming that a narrow crystal filter is in use (close to the DSP bandwidth), this is not desense. In most cases, we've discovered, the cause is IMD (intermodulation distortion) related to the AGC algorithm. To simulate what happens under pileup conditions, we combined four crystal oscillators with gaps between them of 5, 6, and 7 Hz (a total spread of 18 Hz for the four signals). We then injected the signals into the K3 at an equal level of about S5 and used spectral analysis to examine what happens to the passband. With AGC-F turned on (AGC fast, set to the K3's factory defaults), IMD products came up some 20-25 dB as compared to AGC OFF. The situation could be far worse in an actual on-air situation with more signals, noise, and key clicks. (AGC-S makes only a small improvement.) We ran the same test on several other radios, and verified the AGC-induced IMD characteristics are similar. IMD is generated because AGC can cause mixing between the tones and their harmonics. The faster the decay rate, in general, the more products will be generated. With just one or two signals, most products will be outside the DSP's narrow IF or AF passband. But in a pileup, where signals are greater in number and can be nearly on top of each other, there are many more opportunities for signals to combine. This results in IMD products spaced at 1 to 20 Hz, depending on the time constants, location of the signals, etc. Turning AGC off is one strategy that operators have traditionally used to combat the effects of AGC modulation. It then becomes necessary to ride the gain controls. Neither Lyle nor I have that much patience :) So we took a different approach: keep the AGC on, but reduce its modulation effects to negligible levels by adding a very long hold time. In the field-test firmware, two changes have been made. First, the AGC HLD menu setting, which used to apply only to voice modes, now applies to CW as well. (It still only affects AGC-S, the slow AGC setting.) Second, we increased the range of AGC HLD to facilitate experimentation. What we found is that an AGC hold time of about 1 second, combined with a slower AGC-S decay time, reduces in-band IMD with closely spaced signals by 20-25 dB, making it very similar to turning AGC off. The *attack* time is unaffected, so there is no thumping as you might have with audio-derived AGC. Any new signal peak above the one that starts the hold timer will restart the timer. This hold AGC appears to be useful in many listening situations. It can make voice signals sound cleaner, as well; after all, a voice signal can have many components, and AGC-induced modulation can add IMD products. It also helps with noisy band conditions. The down side to AGC hold is that large signals can charge it up to a high level, reducing gain for the duration of the hold time. But in many cases this is far preferable to the AGC IMD effects, especially if you're listening to many signals at similar amplitudes -- as in a pileup. 73, Wayne, N6KR Lyle, KK7P __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [Elecraft] New K3 Firmware: Pileup-inspired AGC changes
On Wed, 25 Feb 2009 14:39:16 -0500, garyhviz...@cfl.rr.com wrote: Does this new firmware eliminate the need for really narrow roofing filters? Does it make them even more useful? Does it not have any bearing? The benefit of all of this software tweaking and the roofing filters and the operator working hard to learn the radio and radios in general are all additive! Someone just posted that they had trouble in pileups during the contest last weekend, but the radio worked better when they turned on the attenuator and turned down the RF gain. DUH! I learned that in 1957 -- but younger operators never learned it, since modern radios depend so heavily on AGC. 73, Jim K9YC __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
Re: [Elecraft] New K3 Firmware: Pileup-inspired AGC changes
Don Rasmussen wrote: Anyone care to take a guess as to how long an anomoly like this would live in any other mass produced HF transceiver? My guess - the life of the radio. Maybe the Flex guys would get to it. With Elecraft, the issue was identified on the weekend, and here it is Wednesday of the same week, the engineers understand the effect and offer test software for it. Kudos! Indeed! Just one example. As I understand this problem the Yaesu FT-1000MP suffers from the same (lets call it) AGC IMD. On the MP I have noticed it myself and others too but it is not widely written about. Very glad to see that it possibly can be fixed on the K3. 73 Jim SM2EKM __ Elecraft mailing list Home: http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/mmfaq.htm Post: mailto:Elecraft@mailman.qth.net This list hosted by: http://www.qsl.net Please help support this email list: http://www.qsl.net/donate.html
