Re: Topband: Digital mode spurious issues
No transformer is necessary. Simply bond from chassis to chassis of all the interconnected equipment, and, if possible, get power for all of it from the same AC outlet. That doesn't always work, Jim. As a matter of fact it is a generally bad idea, because if a connection develops any resistance you wind up with hum and noise. We would have been thrown out by the ear if we were caught bonding cabinets to stop unbalanced line ground loop hum or noise at a BC station. Our radios and equipment have common chassis grounds for power supplies, and the currents on ground leads can be 20 amperes or more. If the bond lead has .01 ohms resistance, there is the potential for over .2 volts hum or noise. A transformer, on the other hand, works flawlessly. The sole drawback is fidelity, but that is not an issue even with very cheap transformers for our communications stuff. My headphone lines, because they serve multiple desks, all have isolation transformers. I suppose I could run a big copper buss bar across the room, but it seems more logical and safer to just spend $2 on a transformer at each radio. :) 73 Tom _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Digital mode spurious issues
On 1/28/2014 12:32 PM, Mike Waters wrote: If you see hum from a ground loop, then simply isolate the audio line using an audio transformer from an old 56k modem. No transformer is necessary. Simply bond from chassis to chassis of all the interconnected equipment, and, if possible, get power for all of it from the same AC outlet. 73, Jim K9YC _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Digital mode spurious issues
I finally got around to installing WSJT-X. I haven't even read the manual, but it's decoding JT65 (and maybe JT9) signals on 160 and displaying callsigns just fine. You don't even have to tune the signals in, they just have to be in the passband. The software does it all for you. There are many software adjustments, and I don't yet know what they do. It worked fine without fiddling with anything except the audio level. I also selected JT9+JT65, assuming that doing so would display signals on either of those modes. Plug the rig's speaker into the mic input on your PC's sound card and tune to 1838.0 USB. If you see hum from a ground loop, then simply isolate the audio line using an audio transformer from an old 56k modem. (I put a pot in there too, as I was overdriving the sound card input without it.) Adjust the volume until you see noise on the WSJT waterfall, and go do something else while it collects and displays info. Intermod from overdriven audio can be seen easier of you turn up the volume so the waterfall is brighter. And it would help a lot if you played with PSK31 first (perhaps in Fldigi or Digipan), and saw what an overdriven PSK31 signal on the waterfall looks like. I saw several callsigns that were not visible at the URL below. All looked clean to me, but I didn't look or listen all that close. 73, Mike www.w0btu.com On Mon, Dec 30, 2013 at 10:48 PM, Mike Waters wrote: > Maybe not. > > I got a private e-mail earlier (which I haven't had time to respond to > yet) that stated "To see who is QRV on 160M WSPR at any given time, check at > http://wsprnet.org/drupal/wsprnet/activity > Scroll down to 160M and the stations are listed (those followed by an R > are just receiving)." > > > On Mon, Dec 30, 2013 at 9:55 PM, Tom W8JI wrote: > >> Thanks everyone for the suggestions. I'm going to have to install some >> software to identify some of the signals. >> > > _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Digital mode spurious issues & Ideas for possible resolution
I hit enter by mistake, but that sum's it up from my perspective. -Steve Raas N2JDQ On Thu, Jan 2, 2014 at 6:00 PM, Steven Raas wrote: > > > I know for the year or so I was very active on TB JT65, that > I never once EVER ( I am an east coast station aswell ) worked a single > station In Europe, or any other DX excluding Canada. Not even Mexico on > JT65 or any other 'digital mode'. I truly believe that the dream of regular > DX on 160m JT65 would only be accomplished on a regular or even > semi-regular basis with 2 stations that are slightly below ' Barely > adequately ' equipped, or better. However, many many MANY 160m JT65 Ops are > not even that well equipped, ( myself INCLUDED ). Hence why I tossed the > illusion that JT65 would provide me with a minimalist QSO exchange , > frequently, during the better propagating months. As soon as I switched > into CW , when there WAS prop, qso exchanges were faster & more reliable ( > for DX contacts ) in the event of decent propogation, due to the mass of > goo in between my ears, than most 'weak sig' JT65 160m qso's dx or not. > Fact being , for a reliable JT65 qso, it is frequently necessary for a > signal to not be affected by long fades of QSB, sometimes as most of us > know, lasting minutes, this is common place for many of us with out the > ideal, close to ideal or even adequate receiving set ups. As you can see I > have not left out the exceptions here, I'm sure there are some 160M JT65 > ops, with long beverages, HI-Z's, Pennants & flags ect ect, as well as > efficient radiators & the like, however they are NOT the majority. With > this being said, even myself having done JT65 ALOT on 160m, with a sub sub > par station, it is NOT fair of me to continue to, or others to subject > people whom can, efficiently utilize the spectrum due to our limitations, > without being subject to frequent, occasional, or rare spurious > transmissions, intentional or not. Those of us whom share in my belief of > my past definition of a less than adequate 160m station, are in fact in my > personal belief 'experimenting' on 160m JT65, due to not having, being > limited to, or knowing how to deploy adequate & efficient stations. > > There is much room for interpretation in the phrases I have > used, as I'm sure many will want to mince words & hop into the semantics , > ( that solves or educates nothing / anyone ) fact is, if you or I are > experimenting on 160 jt65 ( like I was, yes I am admitting my own actions > here and lots of it ), I belong in the portion of the band devoted for such > uses, Digital or Experimental. Addressing the DX contacts, I would be > willing to bet that over 99.5% of successful JT65 QSO's , on the 160M band > are not Transoceanic or DX contacts. The possibility of such QSOs, should > not be the deciding factor on JT65 or any digital transmissions being > allowed there. This in fact, may be completely opposite from other bands > during the colder months, such as 80m, where I personally found, these > QSO's are much easier with..a poorly equipped station ( that is in the > digital segment of the band ). I will add, it took me many conversations > with multiple people to follow this belief that I now have, and even tho it > is possible that 'massive , huge, daily, & constant' interference may not > be the norm, why risk the chance? > >I stand by the belief that if properly presented, with facts, > in a non condescending manor, seeking to educate those like myself whom > are, may be or are slightly ignorant on the possibility of an issue here, > that the possibility of continued, additional or further interference > issues , can be drastically reduced. There is also the Manufacture of goods > ( transmitters ) side of things too, which is just as much of an issue, > however that's where the education & sharing of knowledge with others comes > into play. For the majority of us being not able to change our technical > specifications of our transmitters sending base band audio tones in a SSB > mode today, the only thing that can change today, is how & where we choose > to use them. > >I dont believe that the majority of Digi-ops would have issues > with this , as most are there to check things out n see if they 'can do > this' or not. Many, are infact chasing paper or personal goals if that is > the case, such as I was when active. So, in the quest to achieve these > goals within our shared hobby , their information stream is given to them, > threw the web, word of mouth, clubs & publications, just like the rest of > us. If they have no access to factual information regarding the > possibilities of such spurious emissions, is it shame on them for > utilizing their mode of interest there, where suggested by their interest > group(s) and or peers or shame on us, for not educating & informing those > whom have chosen to share their information with like minded individuals? > > > > > > > On Thu, Jan 2
Re: Topband: Digital mode spurious issues & Ideas for possible resolution
I know for the year or so I was very active on TB JT65, that I never once EVER ( I am an east coast station aswell ) worked a single station In Europe, or any other DX excluding Canada. Not even Mexico on JT65 or any other 'digital mode'. I truly believe that the dream of regular DX on 160m JT65 would only be accomplished on a regular or even semi-regular basis with 2 stations that are slightly below ' Barely adequately ' equipped, or better. However, many many MANY 160m JT65 Ops are not even that well equipped, ( myself INCLUDED ). Hence why I tossed the illusion that JT65 would provide me with a minimalist QSO exchange , frequently, during the better propagating months. As soon as I switched into CW , when there WAS prop, qso exchanges were faster & more reliable ( for DX contacts ) in the event of decent propogation, due to the mass of goo in between my ears, than most 'weak sig' JT65 160m qso's dx or not. Fact being , for a reliable JT65 qso, it is frequently necessary for a signal to not be affected by long fades of QSB, sometimes as most of us know, lasting minutes, this is common place for many of us with out the ideal, close to ideal or even adequate receiving set ups. As you can see I have not left out the exceptions here, I'm sure there are some 160M JT65 ops, with long beverages, HI-Z's, Pennants & flags ect ect, as well as efficient radiators & the like, however they are NOT the majority. With this being said, even myself having done JT65 ALOT on 160m, with a sub sub par station, it is NOT fair of me to continue to, or others to subject people whom can, efficiently utilize the spectrum due to our limitations, without being subject to frequent, occasional, or rare spurious transmissions, intentional or not. Those of us whom share in my belief of my past definition of a less than adequate 160m station, are in fact in my personal belief 'experimenting' on 160m JT65, due to not having, being limited to, or knowing how to deploy adequate & efficient stations. There is much room for interpretation in the phrases I have used, as I'm sure many will want to mince words & hop into the semantics , ( that solves or educates nothing / anyone ) fact is, if you or I are experimenting on 160 jt65 ( like I was, yes I am admitting my own actions here and lots of it ), I belong in the portion of the band devoted for such uses, Digital or Experimental. Addressing the DX contacts, I would be willing to bet that over 99.5% of successful JT65 QSO's , on the 160M band are not Transoceanic or DX contacts. The possibility of such QSOs, should not be the deciding factor on JT65 or any digital transmissions being allowed there. This in fact, may be completely opposite from other bands during the colder months, such as 80m, where I personally found, these QSO's are much easier with..a poorly equipped station ( that is in the digital segment of the band ). I will add, it took me many conversations with multiple people to follow this belief that I now have, and even tho it is possible that 'massive , huge, daily, & constant' interference may not be the norm, why risk the chance? I stand by the belief that if properly presented, with facts, in a non condescending manor, seeking to educate those like myself whom are, may be or are slightly ignorant on the possibility of an issue here, that the possibility of continued, additional or further interference issues , can be drastically reduced. There is also the Manufacture of goods ( transmitters ) side of things too, which is just as much of an issue, however that's where the education & sharing of knowledge with others comes into play. For the majority of us being not able to change our technical specifications of our transmitters sending base band audio tones in a SSB mode today, the only thing that can change today, is how & where we choose to use them. I dont believe that the majority of Digi-ops would have issues with this , as most are there to check things out n see if they 'can do this' or not. Many, are infact chasing paper or personal goals if that is the case, such as I was when active. So, in the quest to achieve these goals within our shared hobby , their information stream is given to them, threw the web, word of mouth, clubs & publications, just like the rest of us. If they have no access to factual information regarding the possibilities of such spurious emissions, is it shame on them for utilizing their mode of interest there, where suggested by their interest group(s) and or peers or shame on us, for not educating & informing those whom have chosen to share their information with like minded individuals? On Thu, Jan 2, 2014 at 3:28 PM, Mike Armstrong wrote: > All. herein lies THE major problem with putting the digital guys > elsewhere. JT-65 (and others of that ilk) are NOT ragchew modes. They are > really only useful for award chasing since what is sent is pretty much > limited to calls, lo
Re: Topband: Digital mode spurious issues & Ideas for possible resolution
All. herein lies THE major problem with putting the digital guys elsewhere. JT-65 (and others of that ilk) are NOT ragchew modes. They are really only useful for award chasing since what is sent is pretty much limited to calls, locations and signal strengths. The guys using these modes (the JT series) aren't having lengthy conversations. So shuttling them off to places that are used mainly for chewing the rag doesn't do them any good at all. They are chasing states and DX. For anyone not familiar with the actual "content" of a JT65 QSO, go to the WSJT web site and take a look. As I mentioned, the QSO "content" is pretty limited and meant for a specific purpose. making and confirming a qso.. and that is about it. I don't want to start a firestorm on ragchewing vs contest-type qsos. I just wanted to inform those who may be unfamiliar with these modes that their purpose is TRULY dxing and state chasing, for lack of a better way to explain them. Fair Winds Mike (AB7ZU) Kuhi no ka lima, hele no ka maka > On Jan 2, 2014, at 13:16, Chris G3SVL wrote: > > >> On 02/01/2014 18:20, Shoppa, Tim wrote: >> I think we could encourage use of ARRL band plan, by not complaining when >> digital modes show up in 1800-1810. > Tim, > > That doesn't help those of us in Region 1 who don't have access to 1800 - > 1810? > > 73 & HNY > > Chris, G3SVL > > _ > Topband Reflector Archives - http://www.contesting.com/_topband _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Digital mode spurious issues & Ideas for possible resolution
On 02/01/2014 18:20, Shoppa, Tim wrote: I think we could encourage use of ARRL band plan, by not complaining when digital modes show up in 1800-1810. Tim, That doesn't help those of us in Region 1 who don't have access to 1800 - 1810? 73 & HNY Chris, G3SVL _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Digital mode spurious issues & Ideas for possible resolution
I think we could encourage use of ARRL band plan, by not complaining when digital modes show up in 1800-1810. Tim N3QE - Original Message - From: Steven Raas [mailto:sjr...@gmail.com] Sent: Thursday, January 02, 2014 12:47 PM To: topband@contesting.com Subject: Topband: Digital mode spurious issues & Ideas for possible resolution I have an idea, it may be far fetched, but I think a good one none the less. As a group we can create a document, in short explaining the issues that are & hand , that the technical people will see and understand & the non-technical end users ( not saying all end-users are non-technical ) will also understand, our best idea for resolution and present this document with 'signatures' , to the major 'digita'l reflectors, groups, creators and experimenters, outlining the benefits for both groups interested. For kicks, I looked up the ARRL's 'band plan' http://www.arrl.org/band-plan and their document says 1800-1810 ( digital ) & 1995-2000 (beacons), I personally believe that the WSPR stuff for prop reports should go there ( some is not as we all know ) because its not 2-way com stuff to the best of my knowledge, their just low power prop beacons. Yes I do understand that the ways of the ARRL are not always great.. however I can see benefits for us all on a move of the digital stuff, just as many that are following this thread can see aswell. This may have been done before & possibly no traction came of it, I'm not sure, however if this is a problem that is affecting masses, it should be addressed, in kind to the masses, until resolved. Just a thought...comments & suggestions? -Steve Raas N2JDQ _ Topband Reflector Archives - http://www.contesting.com/_topband _ Topband Reflector Archives - http://www.contesting.com/_topband
Topband: Digital mode spurious issues & Ideas for possible resolution
I have an idea, it may be far fetched, but I think a good one none the less. As a group we can create a document, in short explaining the issues that are & hand , that the technical people will see and understand & the non-technical end users ( not saying all end-users are non-technical ) will also understand, our best idea for resolution and present this document with 'signatures' , to the major 'digita'l reflectors, groups, creators and experimenters, outlining the benefits for both groups interested. For kicks, I looked up the ARRL's 'band plan' http://www.arrl.org/band-plan and their document says 1800-1810 ( digital ) & 1995-2000 (beacons), I personally believe that the WSPR stuff for prop reports should go there ( some is not as we all know ) because its not 2-way com stuff to the best of my knowledge, their just low power prop beacons. Yes I do understand that the ways of the ARRL are not always great.. however I can see benefits for us all on a move of the digital stuff, just as many that are following this thread can see aswell. This may have been done before & possibly no traction came of it, I'm not sure, however if this is a problem that is affecting masses, it should be addressed, in kind to the masses, until resolved. Just a thought...comments & suggestions? -Steve Raas N2JDQ _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Digital mode spurious issues
AFAIK, all non-DSP rigs with synthesizers work this way. Assuming you want the output frequency to be derived from the master clock frequency, there is no easy way to shift an RF carrier. You can't use a free running oscillator, because it won't be derived from the master clock frequency. You can't switch between a mark synthesizer and a space synthesizer because of transients. If you try to key the programmed frequency of a BFO synthesizer, the PLL will probably go out of lock momentarily, producing garbage. Also, it may not be fast enough to keep up with RTTY. After considering all this (as a very experienced synthesizer designer) it is hard for me to blame the designers for using AFSK. It is easy to do it much better, and it would only cost pennies extra at the most. The signal could be generated by the normal SSB system and then run through a narrow IF filter. Problem solved. They could have done CW the same way, or in a similar fashion, with an unshaped off-on carrier through a narrow filter. They just didn't think to use the parts they already had in the radio. But that isn't this issue. This issue is they run baseband audio from a computer into a SSB transmitter to generate TX signals. This means it is really a SSB transmitter processing the tones, and they don't even restrict bandwidth with a narrow filter. That is really the entire issue. Instead of a narrow filter cleaning up stuff, it all goes through a SSB filter. Anyone with a computer and a little skill can invent a "new mode". It's just bad engineering to stick that stuff near weak signals, because the problem can only be fixed at the transmitter. 73 Tom _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Digital mode spurious issues
An interesting point from Tom re SSB modulation added problems. A really informative website re "plain old RTTY" is http://www.frontiernet.net/~aflowers/k3rtty/k3rtty.html and is a good introduction to the technical complexity of digital modulation systems and what to do to make "better" RTTY signals. The W7AY work is referenced w7ay.net but the site was not available when I tried it. Is there any good testing posted for other modes and on other radios and software generators? Grant KZ1W On 12/31/2013 7:13 AM, Tom W8JI wrote: Well, I certainly have to agree, Tom, if the signal on the desired sideband is just a single shifting tone. Might get messier if an sudio stage or A/D is driven into limiting and producing harmonic distortion at audio, I guess. The entire thing for digital modes was poorly planned. I'm surprised no one objected to the frequency choices (of Europe), because they are technically always going to be a long term problem. The frequency range really could not have been more poorly planned for future long-term band use. Any digital mode piped into the SSB transmitter system, like it or not, is really SSB modulated. It has all the noise, carrier, and opposite sideband suppression issues, as well as sensitivity to levels. If they transmit 1835-40 using USB on the radio, the opposite sideband falls in the 1832 and upward range. IMD can be anywhere, if it is a multiple tone at the same time mode. Harmonic distortion is upward from the carrier on USB. Collins got burned by this. They tried running a pure audio tone into the SSB transmitter of the early S line to generate CW. The FCC (back when they did enforcement) starting handing out pink slips left and right to Collins owners. Any carrier, noise, or harmonic distortion at all resulted in an FCC citation, so Collins had to convert transmitters back to a keyed carrier. Anything converted to RF in a SSB transmitter system really belongs off by itself, well away from other operation. It's really a technical issue that will always exist, because the basic RF generation system or idea is flawed. _ Topband Reflector Archives - http://www.contesting.com/_topband _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Digital mode spurious issues
- Original Message - From: To: Sent: Tuesday, December 31, 2013 12:00 PM Subject: Topband Digest, Vol 132, Issue 30 Send Topband mailing list submissions to topband@contesting.com To subscribe or unsubscribe via the World Wide Web, visit http://lists.contesting.com/mailman/listinfo/topband or, via email, send a message with subject or body 'help' to topband-requ...@contesting.com You can reach the person managing the list at topband-ow...@contesting.com My Kenwood TS-590S "NR" and A-notch "BC" controls when properly adjusted perform magic with this scenario! *Happy New Year* KB8NTY http://www.rossradio.net/ When replying, please edit your Subject line so it is more specific than "Re: Contents of Topband digest..." Today's Topics: 1. Digital mode spurious issues (Tom W8JI) 2. Re: Digital mode spurious issues (Mike Waters) 3. Re: Digital mode spurious issues (Jim Brown) 4. Re: Digital mode spurious issues (Richard (Rick) Karlquist) 5. Re: Digital mode spurious issues (Joe Subich, W4TV) 6. Re: Digital mode spurious issues (Charlie Cunningham) 7. Re: Digital mode spurious issues (Jim Brown) 8. Re: [CQ-Contest] Stew Perry Streaming Audio (Herb Schoenbohm) 9. Re: Digital mode spurious issues (Grant Saviers) 10. Re: Digital mode spurious issues (W2RU - Bud Hippisley) 11. Re: Digital mode spurious issues (Mike Waters) 12. Re: Digital mode spurious issues (Charlie Cunningham) 13. Re: Digital mode spurious issues (JC N4IS) 14. Re: Digital mode spurious issues (Mike Waters) 15. Re: Digital mode spurious issues (Tom W8JI) 16. Re: Digital mode spurious issues (Charlie Cunningham) 17. Re: Digital mode spurious issues (Steven Raas) 18. Re: Digital mode spurious issues (Mike Waters) 19. Re: Stew Perry Streaming Audio (Shoppa, Tim) 20. CA/OR/AZ activity during Stew Perry - anecdotal data (Barry N1EU) 21. Re: Digital mode spurious issues (Tom W8JI) -- Message: 1 Date: Mon, 30 Dec 2013 12:11:49 -0500 From: "Tom W8JI" To: "Topband" Subject: Topband: Digital mode spurious issues Message-ID: Content-Type: text/plain; format=flowed; charset="iso-8859-1"; reply-type=response I have not been on the air for a year or so, but decided to get back on. I was listening to a DX station around 1833 when a digimode station up roughly around 1837 came on with a LSB "spurious" signal on 1833. His signal was a series of slowly changing stepped tones. I don't know what mode that was. His unwanted sideband suppression was about 40 dB, but that was not nearly enough. He was 15 dB out of noise with his unwanted sideband. Does anyone know of a universal software to decode signals? Since the FCC does not require a CW ID, I think that is the only way to identify stations. I assume: 1.) Operators are unlikely to accept they have a problem if they are getting good reports on the intentional signal 2.) Some rigs just should not be used for digimodes (this was a sideband suppression issue) 3.) Those who unwisely placed digimode subbands next to popular weak signal areas, especially when sideband selection produces a supurious that falls in weak signal areas, are unlikely to rethink the poor placement or poor advice on selecting sidebands 4.) With a little work to convince them, most digital ops with radio problems would avoid operating 73 Tom -- Message: 2 Date: Mon, 30 Dec 2013 12:30:34 -0600 From: Mike Waters To: Tom W8JI Cc: Topband Subject: Re: Topband: Digital mode spurious issues Message-ID: Content-Type: text/plain; charset=ISO-8859-1 Tom, I believe the mode that operates at 1873-1838 is JT65, and WSJT is needed to decode it. I never tried it. It was developed by K1JT for weak-signal and EME work. http://www.physics.princeton.edu/pulsar/K1JT/wsjt.html A common scenario with digital modes is that the audio into the mic input is too high, causing unwanted spurs. 73, Mike www.w0btu.com On Mon, Dec 30, 2013 at 11:11 AM, Tom W8JI wrote: ... a digimode station up roughly around 1837 came on with a LSB "spurious" signal on 1833. His signal was a series of slowly changing stepped tones. I don't know what mode that was. His unwanted sideband suppression was about 40 dB, but that was not nearly enough. He was 15 dB out of noise with his unwanted sideband. Does anyone know of a universal software to decode signals? Since the FCC does not require a CW ID, I think that is the only way to identify stations. ... -- Message: 3 Date: Mon, 30 Dec 2013 14:17:57 -0800 From: Jim Brown To: topband@contesting.com Subject: Re: Topband: Digital mode spurious issues Message-ID: <52c1f115.6050...@audiosystemsgroup.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed
Re: Topband: Digital mode spurious issues
On Tue, Dec 31, 2013 at 2:21 PM, Tom W8JI wrote: > . It would be much better to actually shift a carrier, and not do the > baseband audio signal run though a balanced modulator and then through a > sideband filter. Better yet to generate the best transition waveform in data (far more difficult to do in analog methods) and via a DAC create a completely clean signal at the TX IF level. Then only conversion and RF issues to keep clean. Then adjustments to waveform are in firmware. 73, Guy. _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Digital mode spurious issues
On 12/31/2013 11:21 AM, Tom W8JI wrote: I've never looked at the FT1000, but I doubt that is a clean system. It would still be like a SSB transmitter with audio signals if that is how they do it. It would be much better to actually shift a carrier, and not do the baseband audio signal run though a balanced modulator and then through a sideband filter. AFAIK, all non-DSP rigs with synthesizers work this way. Assuming you want the output frequency to be derived from the master clock frequency, there is no easy way to shift an RF carrier. You can't use a free running oscillator, because it won't be derived from the master clock frequency. You can't switch between a mark synthesizer and a space synthesizer because of transients. If you try to key the programmed frequency of a BFO synthesizer, the PLL will probably go out of lock momentarily, producing garbage. Also, it may not be fast enough to keep up with RTTY. After considering all this (as a very experienced synthesizer designer) it is hard for me to blame the designers for using AFSK. I imagine I could make a synthesized RF FSK system if I wanted to go to enough trouble, but obviously Yaesu's resources were limited. Rick N6RK _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Digital mode spurious issues
As utterly simple as it is to shift a VFO, it's almost hard to believe that any major manufacturer would do it with audio. When I was heavily into HF RTTY software development years ago, it was a trivial thing to FSK my Collins 32S-3's VFO. I just connected one pin of the RS-232 port through a resistor to a switching diode and trimmer capacitor connected to the VFO tube socket. It turned out to be much superior to using audio. It was the only way I could keep the amplitude of the mark and space freqs exactly the same, which turned out to be very important when conditions were less than ideal. If rig manufacturers are not informed of this need, we can expect little to change. 73, Mike www.w0btu.com On Tue, Dec 31, 2013 at 1:21 PM, Tom W8JI wrote: > In my FT-1000D, if you try to use FSK mode for RTTY it turns out that the >> rig is still running AFSK, using an internal audio source. >> > > It would be much better to actually shift a carrier, and not do the > baseband audio signal... > _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Digital mode spurious issues
On 12/31/2013 11:15 AM, Tom W8JI wrote: We are not talking about momentary sidebands generated during level transitions. We are talking about spurious signals up and down the band. You may be, but I am talking about the larger picture. 73, Jim K9YC _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Digital mode spurious issues
How is this different than RTTY using the AFSK method? In my FT-1000D, if you try to use FSK mode for RTTY it turns out that the rig is still running AFSK, using an internal audio source. I've never looked at the FT1000, but I doubt that is a clean system. It would still be like a SSB transmitter with audio signals if that is how they do it. It would be much better to actually shift a carrier, and not do the baseband audio signal run though a balanced modulator and then through a sideband filter. _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Digital mode spurious issues
Actually, IMD can be produced by ANY keying waveform -- for example, the envelope of a CW or RTTY signal. Let's not divert the issue. A rise and fall is always composed of many frequencies making up sidebands, otherwise it would have no shaping. Even CW is an AM signal, when we look at rise and fall. We are not talking about momentary sidebands generated during level transitions. We are talking about spurious signals up and down the band. _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Digital mode spurious issues
On 12/30/2013 7:55 PM, Tom W8JI wrote: IMD **requires** two or more signals at once, and does not appear anything like sideband leakage. Actually, IMD can be produced by ANY keying waveform -- for example, the envelope of a CW or RTTY signal. To understand this, think of the keying envelope of a signal as the amplitude modulation of a carrier by a square wave, which, from a spectral point of view, consists of many harmonics, the relative strength of which vary with the rise time. Indeed, clicks are the IM products of that envelope. During contests, I often hear clicks from RTTY rigs that have high levels of IMD somewhere in the system. Elecraft recently released new firmware that significantly reduces the TX bandwidth of FSK RTTY by carefully shaping the keying waveform in the same manner that they do for the CW waveform. There's also the mechanism of incidental AM as the result of non-flat response of the filter through which the signal is being transmitted and received. This is clearly visible as flicker of a wattmeter on the output. I noticed a significant reduction in this when I replaced the 2.7 kHz 5-pole filter in my K3 with a 2.8 kHz 8-pole filter. On 12/31/2013 7:13 AM, Tom W8JI wrote: The entire thing for digital modes was poorly planned. I think it's long past time to stop wringing our hands about a very minor issue and start worrying about more consequential ones. Nothing short of official allocation restrictions by national bodies (FCC and equivalent around the world) is going to change the frequencies used by various digital modes within CW sub-bands. Besides -- the vast majority of those using WSJT and PSK on the HF bands are running flea power -- 20W is QRO for this crowd. Not only that, this group of operators is, as a whole, more or less self-policing. All are using some sort of waterfall display, and it's common for a dozen or more QSOs to be taking place in the 2kHz or so bandwidth of a SSB signal, so anyone generating audio distortion is going to be quickly noted and they will let each other know on email reflectors devoted to JT65. Granted they won't notice the inferior sideband suppression that W8JI has observed, but FWIW, I hear a ton of that during most SSB contests. I think we ought to be paying a lot more attention to the issues highlighted in this report by SM5BSZ, which is quite illuminating with respect to the RF trash produced by a selection of popular rigs. http://www.sm5bsz.com/dynrange/dubus313.pdf .It shows, for example, that the phase noise from a K3 is at least 17 dB lower in amplitude than most other rigs, including the IC-7600. 17dB means that there is 50 times the power (more than three real S-units) in the trash, and some rigs are a lot worse than the 7600. In any contest, these rigs are all running at least 100W, the trash produced is broadband and cumulative, most of them are driving power amps of varying quality that boost the level of the trash by 10-15 dB, and there are a LOT more of them than the handful of digital operators. Given these realities, it's just plain silly to obsess over a few QRP digital signals. It would be far more productive to work on reducing that trash (by applying peer pressure to get these guys to clean up their act), which is raising the overall noise level on all of our bands. As to the post about WSPR -- although it was developed by K1JT, it is an entirely different system designed to observe worldwide propagation in real time, uses an entirely different modulation method, and transmitters typically operate at 1W or less. The WSPR website reports only on the reception of WSPR transmissions. It does not report JT65 transmissions. Most operators using JT65 on the HF bands use software called JT65HF, written by W6CQZ using K1JT's protocols. It's a multi-decoder system with a waterfall display. It can optionally be set to report all received signals to W6CQZ's website. I've used it to test the effectiveness of my 160M antennas, by statistically averaging MANY reports of my signal from stations east of the Mississippi as I switch from one antenna to another. http://jt65.w6cqz.org/receptions.html A fair number of excellent operators use JT65. I've worked KH6LC and NO3M on JT65 on 160M. 73, Jim K9YC _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Digital mode spurious issues
It's really not any different. The question is whether the levels and output are engineered clean, and KEPT that way. That can be done completely internally to a TRX and maintained. But when the (audio baseband) signal is generated external to the radio then all of the issues of off-level-for-optimum-signal, or distortion supplied to the radio, come into play, and quite often the issues are unknown or undetected. The best thing is for all modes to be generated in TX DSP (not baseband), but that is a journey not sure many transceiver manufacturers are willing to make. Elecraft does it for some modes in the K3. 73 & HNY Guy On Tue, Dec 31, 2013 at 1:08 PM, Richard (Rick) Karlquist < rich...@karlquist.com> wrote: > > > On 12/31/2013 7:13 AM, Tom W8JI wrote: > >> >> Collins got burned by this. They tried running a pure audio tone into >> the SSB transmitter of the early S line to generate CW. The FCC (back >> > > How is this different than RTTY using the AFSK method? > In my FT-1000D, if you try to use FSK mode for RTTY it > turns out that the rig is still running AFSK, using > an internal audio source. > > Rick N6RK > > _ > Topband Reflector Archives - http://www.contesting.com/_topband > _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Digital mode spurious issues
On 12/31/2013 7:13 AM, Tom W8JI wrote: Collins got burned by this. They tried running a pure audio tone into the SSB transmitter of the early S line to generate CW. The FCC (back How is this different than RTTY using the AFSK method? In my FT-1000D, if you try to use FSK mode for RTTY it turns out that the rig is still running AFSK, using an internal audio source. Rick N6RK _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Digital mode spurious issues
Well, I certainly have to agree, Tom, if the signal on the desired sideband is just a single shifting tone. Might get messier if an sudio stage or A/D is driven into limiting and producing harmonic distortion at audio, I guess. The entire thing for digital modes was poorly planned. I'm surprised no one objected to the frequency choices (of Europe), because they are technically always going to be a long term problem. The frequency range really could not have been more poorly planned for future long-term band use. Any digital mode piped into the SSB transmitter system, like it or not, is really SSB modulated. It has all the noise, carrier, and opposite sideband suppression issues, as well as sensitivity to levels. If they transmit 1835-40 using USB on the radio, the opposite sideband falls in the 1832 and upward range. IMD can be anywhere, if it is a multiple tone at the same time mode. Harmonic distortion is upward from the carrier on USB. Collins got burned by this. They tried running a pure audio tone into the SSB transmitter of the early S line to generate CW. The FCC (back when they did enforcement) starting handing out pink slips left and right to Collins owners. Any carrier, noise, or harmonic distortion at all resulted in an FCC citation, so Collins had to convert transmitters back to a keyed carrier. Anything converted to RF in a SSB transmitter system really belongs off by itself, well away from other operation. It's really a technical issue that will always exist, because the basic RF generation system or idea is flawed. _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Digital mode spurious issues
Maybe not. I got a private e-mail earlier (which I haven't had time to respond to yet) that stated "To see who is QRV on 160M WSPR at any given time, check at http://wsprnet.org/drupal/wsprnet/activity Scroll down to 160M and the stations are listed (those followed by an R are just receiving)." 73, Mike www.w0btu.com On Mon, Dec 30, 2013 at 9:55 PM, Tom W8JI wrote: > Thanks everyone for the suggestions. I'm going to have to install some > software to identify some of the signals. > _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Digital mode spurious issues
Tom, I would have to agree. Let me also add my personal experiences on 160m JT65, were good, however, at the latter stages of me being QRV on the band, I was very politely spoken to, and delightfully educated on such matters by Les, KL7J , whom really gave me some great insight on a then and still new band to me, for this I am ever grateful. We tried to contact on many occasions a few years back on 160M JT-65, however the latter attempts were lower in the band , 1807 ish or so if I recall. I was one of the many daily 160M ops for quite some time, but after learning, & progressing, if I was QRV on 160 at the moment, I would take it ( digital ops ) down the band. I will also admit, that I was lured with the possibility ( at those times ) of my 1st trans-oceanic 160m QSO using JT65 ( or any mode ) , with my experiences now, I would say that waiting for prop, and running 4 or 5 cw q's was much easier for those 1st trans-oceanic q's. Not to mention that the long deep fades that I had ( with very very limited antennas which are frequently common with 160 digi mode ops ) would not be very beneficial for JT65 ' long haul / high qsb qso's, however this is not always the case. I can even say that to this day, I had yet to work any DX on 160m JT-65, cw now, is a different story thankfully :) There is also WSPR activity in that area of the band if I recall ( that may have changed ) amongst a few others. I think that progress could be made in getting the digi ops to qsy, perhaps to the lower end of the band, I'll be honest tho, I think that the hardest part would be getting the word out to the masses, however when presented with facts, and honest concern with the forsight of keeping the band active and everyone happy, my guess is that few would gripe.. but the masses just want to make qso's like the rest of us, and would in time oblige. I digress..have a great new year everyone & enjoy ! -Steve Raas N2JDQ On Mon, Dec 30, 2013 at 10:55 PM, Tom W8JI wrote: > Thanks everyone for the suggestions. I'm going to have to install some > software to identify some of the signals. > > > > I would think that IMD products in a high-level PA that is over-driven >> beyond good linearity limits could add some junk in the "undesired >> sideband"? FWIW >> >> > IMD **requires** two or more signals at once, and does not appear anything > like sideband leakage. This was a single shifting tone, and the lower > frequency signal went the opposite way but the same amount as the main > signal with shifts. That is classic for inadequate sideband suppression. > > There are multiple problems with using SSB to transmit audio tones and > "thinking" it is a pure digi mode. > > 1.) things like this do not show on almost all digi waterfalls because > they are out of passband of the other fellows receiver. > > 2.) SSB carrier, noise, and opposite sideband suppression is limited by > the radio quality > > 3.) output purity is also limited by audio input purity, which includes > audio line issues > > 4.) most digi operators do not have the low noise antennas most DXers > have, and cannot hear some fairly strong signals. They are often on > digimodes because of that! > > 5.) radios have terrible SSB transmitter performance compared to even fair > receivers, so the transmitters often set the adjacent channel interference > levels > > Placing digimodes near weak signal areas is not very wise frequency > planning, but there is nothing anyone can do about it. > _ > Topband Reflector Archives - http://www.contesting.com/_topband > _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Digital mode spurious issues
Well, I certainly have to agree, Tom, if the signal on the desired sideband is just a single shifting tone. Might get messier if an sudio stage or A/D is driven into limiting and producing harmonic distortion at audio, I guess. 73, Charlie, K4OTV -Original Message- From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of Tom W8JI Sent: Monday, December 30, 2013 10:56 PM To: topband@contesting.com Subject: Re: Topband: Digital mode spurious issues Thanks everyone for the suggestions. I'm going to have to install some software to identify some of the signals. >I would think that IMD products in a high-level PA that is over-driven > beyond good linearity limits could add some junk in the "undesired > sideband"? FWIW > IMD **requires** two or more signals at once, and does not appear anything like sideband leakage. This was a single shifting tone, and the lower frequency signal went the opposite way but the same amount as the main signal with shifts. That is classic for inadequate sideband suppression. There are multiple problems with using SSB to transmit audio tones and "thinking" it is a pure digi mode. 1.) things like this do not show on almost all digi waterfalls because they are out of passband of the other fellows receiver. 2.) SSB carrier, noise, and opposite sideband suppression is limited by the radio quality 3.) output purity is also limited by audio input purity, which includes audio line issues 4.) most digi operators do not have the low noise antennas most DXers have, and cannot hear some fairly strong signals. They are often on digimodes because of that! 5.) radios have terrible SSB transmitter performance compared to even fair receivers, so the transmitters often set the adjacent channel interference levels Placing digimodes near weak signal areas is not very wise frequency planning, but there is nothing anyone can do about it. _ Topband Reflector Archives - http://www.contesting.com/_topband _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Digital mode spurious issues
Thanks everyone for the suggestions. I'm going to have to install some software to identify some of the signals. I would think that IMD products in a high-level PA that is over-driven beyond good linearity limits could add some junk in the "undesired sideband"? FWIW IMD **requires** two or more signals at once, and does not appear anything like sideband leakage. This was a single shifting tone, and the lower frequency signal went the opposite way but the same amount as the main signal with shifts. That is classic for inadequate sideband suppression. There are multiple problems with using SSB to transmit audio tones and "thinking" it is a pure digi mode. 1.) things like this do not show on almost all digi waterfalls because they are out of passband of the other fellows receiver. 2.) SSB carrier, noise, and opposite sideband suppression is limited by the radio quality 3.) output purity is also limited by audio input purity, which includes audio line issues 4.) most digi operators do not have the low noise antennas most DXers have, and cannot hear some fairly strong signals. They are often on digimodes because of that! 5.) radios have terrible SSB transmitter performance compared to even fair receivers, so the transmitters often set the adjacent channel interference levels Placing digimodes near weak signal areas is not very wise frequency planning, but there is nothing anyone can do about it. _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Digital mode spurious issues
Bingo! The waterfall display was a wonderful invention, wasn't it? And I don't even use SDR. (Yet.) When I used to operate PSK31, I adjusted the audio levels with my own signal displayed on the waterfall, and so it was easy to see when the input from the sound card was too high. The spurs from AF overload are very easy to see on the waterfall. 73, Mike www.w0btu.com On Mon, Dec 30, 2013 at 8:50 PM, JC N4IS wrote: > > Using a SDR water fall it is easy to see the signal transitions and > associate the trash with the main signal. I've seen several spoors every 10 > KHz almost 100KHz up and down 1838. This is a growing problem. > _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Digital mode spurious issues
Tom, Mike is right, the issue with audio overload is complex for most of new radios, most of them have A/D just at the MIC input, if the A/D overloads the RF chain is compromised. These radios have no actual filters, everything is digital, like the IC7600. An analog radio is BW limited by the SSB crystal filter but SDR don't, when the A/D overloads, there are spoors everywhere several KHz far from the carrier; enough to trash the entire band. Using a SDR water fall it is easy to see the signal transitions and associate the trash with the main signal. I've seen several spoors every 10 KHz almost 100KHz up and down 1838. This is a growing problem. 73, JC N4IS -Original Message- From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of Mike Waters Sent: Monday, December 30, 2013 1:31 PM To: Tom W8JI Cc: Topband Subject: Re: Topband: Digital mode spurious issues Tom, I believe the mode that operates at 1873-1838 is JT65, and WSJT is needed to decode it. I never tried it. It was developed by K1JT for weak-signal and EME work. http://www.physics.princeton.edu/pulsar/K1JT/wsjt.html A common scenario with digital modes is that the audio into the mic input is too high, causing unwanted spurs. 73, Mike www.w0btu.com On Mon, Dec 30, 2013 at 11:11 AM, Tom W8JI wrote: > ... a digimode station up roughly around 1837 came on with a LSB > "spurious" signal on 1833. His signal was a series of slowly changing > stepped tones. I don't know what mode that was. His unwanted sideband > suppression was about 40 dB, but that was not nearly enough. He was 15 > dB out of noise with his unwanted sideband. > > Does anyone know of a universal software to decode signals? Since the > FCC does not require a CW ID, I think that is the only way to identify > stations. ... > _ Topband Reflector Archives - http://www.contesting.com/_topband _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Digital mode spurious issues
Hi, Jim Well as one who has been an RF and radio engineer and designer for 40+ years, I have to agree with most all of your points. Great deal of truth in there, but so many guys don't appreciate all those things and their inclination is "crank it to the right" and "the "louder you shout, the further you get"! And they are looking for large meter excursions. To appreciate the tendency to overdrive transmitters and amplifiers. One need only listen to the the prevalence of awful key clicks and SSB splatter in contests! (And "real men" use vacuum tubes to develop "real power"! :-) ) 73, Charie, K4OTV -Original Message- From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of Jim Brown Sent: Monday, December 30, 2013 6:52 PM To: topband@contesting.com Subject: Re: Topband: Digital mode spurious issues On 12/30/2013 3:13 PM, Charlie Cunningham wrote: > I would think that IMD products in a high-level PA that is over-driven > beyond good linearity limits could add some junk in the "undesired > sideband"? FWIW Yes. Indeed, any IMD would do that. K6XX is an Elecraft engineer who worked on their KPA500, among other things, and looked at a lot of competing power amps in preparation for doing so. Bob recently did an excellent tutorial presentation to a meeting of the Northern California Contest Club about the root causes of sideband trash, the general properties of various amplifier types, and how to minimize the trash. In general: Distortion products increase when the antenna is poorly matched to the amplifier That's true whether it's a tuned tube amp or a fixed tuned solid state amp -- in other words, the tube amp must be carefully tuned, and the solid state amp should be used with a tuner if the antenna is not an ideal match. Distortion products increase as power supply voltage decreases. In other words, a rig designed to run on 13.8 volts will be much cleaner at 13.8 volts than at 12V. Most solid state output stages are cleaner at half power than at full power. That means that a rig will be cleaner driving a power amp at 50W than at 100 W. Using AGC between the power amp and the rig to set output level is a recipe for sideband trash. A properly tuned hollow state power amp is typically 8-10 dB cleaner than the best solid state amps. Fast rise time of the keying waveform is the major cause of clicks W8JI and others long ago identified this as the cause of the FT1000-series rigs awful clicks, and fixed them. The rise time of some rigs (notably the IC7600) is adjustable, and only the slowest rise time is acceptable. The K3 uses an optimally shaped keying waveform (which designer N6KR calls "sigmoidal") to minimize clicks, and it is not user adjustable. Most ICOM rigs have overshoot that also causes clicks. Something I learned from N6KR a few days ago is that the very low level of sideband trash from a K3 is the result of two design elements. First, the synthesizer is very clean.. Second, they run it through the TX crystal filter, which gets rid of trash more distant from the carrier. 73, Jim K9YC _ Topband Reflector Archives - http://www.contesting.com/_topband _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Digital mode spurious issues
You are right. There is no universal software that can do that. But I used to code software, and I'm convinced that the status quo in amateur digital software can be greatly improved. See http://www.eham.net/ehamforum/smf/index.php?topic=80740.0 . If anyone wants to take up where we left off on that eHam thread, then let's take the discussion there. 73, Mike www.w0btu.com On Mon, Dec 30, 2013 at 7:12 PM, Grant Saviers wrote: > > If "universal" means automatic selection of the correct decoding mode, > that would be a challenge! > _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Digital mode spurious issues
This is a little off-topic relative to the Subject line, but extremely relevant to enjoyable Topband operating: On Dec 30, 2013, at 6:51 38PM, Jim Brown wrote: > Fast rise time of the keying waveform is the major cause of clicks. W8JI and > others long ago identified this as the cause of the FT1000-series rigs awful > clicks, and fixed them. The rise time of some rigs (notably the IC7600) is > adjustable, and only the slowest rise time is acceptable. Add the venerable Kenwood TS-950SDX to the list of rigs with user-adjustable rise/fall times. And -- as Jim notes -- only the slowest rise time is fully acceptable, despite the pains Kenwood took to carefully "shape" those RF waveforms during their "on" and "off" transition periods. In the case of the 950SDX, the user can select nominal rise/fall times labeled 2, 4, 6, or 8 milliseconds (ms) from one of the configuration menus accessible via the front panel MENU options. A few years back, in extensive tests on a daytime 80-m band with an equally fanatical friend listening critically, we determined that -only- the 8-ms setting was "clean" with respect to click generation. Probably the 6-ms setting would be marginally "OK" if the transmitted signal were not loud anywhere, but since my usual objective when chasing DX on 160 is to be as loud as I can, 6 ms is not really an acceptable solution for maintaining good relations with my close-in Topband "neighbors" here on the east coast of North America. Once we ran those tests, I set the TS-950SDX menu choice to 8 ms, and I've not changed it since. Bud, W2RU _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Digital mode spurious issues
The SignaLink supported software page has a nice summary of software decoders see http://www.tigertronics.com/sl_soft.htm If "universal" means automatic selection of the correct decoding mode, that would be a challenge! Grant KZ1W On 12/30/2013 9:11 AM, Tom W8JI wrote: I have not been on the air for a year or so, but decided to get back on. I was listening to a DX station around 1833 when a digimode station up roughly around 1837 came on with a LSB "spurious" signal on 1833. His signal was a series of slowly changing stepped tones. I don't know what mode that was. His unwanted sideband suppression was about 40 dB, but that was not nearly enough. He was 15 dB out of noise with his unwanted sideband. Does anyone know of a universal software to decode signals? Since the FCC does not require a CW ID, I think that is the only way to identify stations. I assume: 1.) Operators are unlikely to accept they have a problem if they are getting good reports on the intentional signal 2.) Some rigs just should not be used for digimodes (this was a sideband suppression issue) 3.) Those who unwisely placed digimode subbands next to popular weak signal areas, especially when sideband selection produces a supurious that falls in weak signal areas, are unlikely to rethink the poor placement or poor advice on selecting sidebands 4.) With a little work to convince them, most digital ops with radio problems would avoid operating 73 Tom _ Topband Reflector Archives - http://www.contesting.com/_topband _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Digital mode spurious issues
On 12/30/2013 3:13 PM, Charlie Cunningham wrote: I would think that IMD products in a high-level PA that is over-driven beyond good linearity limits could add some junk in the "undesired sideband"? FWIW Yes. Indeed, any IMD would do that. K6XX is an Elecraft engineer who worked on their KPA500, among other things, and looked at a lot of competing power amps in preparation for doing so. Bob recently did an excellent tutorial presentation to a meeting of the Northern California Contest Club about the root causes of sideband trash, the general properties of various amplifier types, and how to minimize the trash. In general: Distortion products increase when the antenna is poorly matched to the amplifier That's true whether it's a tuned tube amp or a fixed tuned solid state amp -- in other words, the tube amp must be carefully tuned, and the solid state amp should be used with a tuner if the antenna is not an ideal match. Distortion products increase as power supply voltage decreases. In other words, a rig designed to run on 13.8 volts will be much cleaner at 13.8 volts than at 12V. Most solid state output stages are cleaner at half power than at full power. That means that a rig will be cleaner driving a power amp at 50W than at 100 W. Using AGC between the power amp and the rig to set output level is a recipe for sideband trash. A properly tuned hollow state power amp is typically 8-10 dB cleaner than the best solid state amps. Fast rise time of the keying waveform is the major cause of clicks W8JI and others long ago identified this as the cause of the FT1000-series rigs awful clicks, and fixed them. The rise time of some rigs (notably the IC7600) is adjustable, and only the slowest rise time is acceptable. The K3 uses an optimally shaped keying waveform (which designer N6KR calls "sigmoidal") to minimize clicks, and it is not user adjustable. Most ICOM rigs have overshoot that also causes clicks. Something I learned from N6KR a few days ago is that the very low level of sideband trash from a K3 is the result of two design elements. First, the synthesizer is very clean.. Second, they run it through the TX crystal filter, which gets rid of trash more distant from the carrier. 73, Jim K9YC _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Digital mode spurious issues
I would think that IMD products in a high-level PA that is over-driven beyond good linearity limits could add some junk in the "undesired sideband"? FWIW Charlie, K4OTV -Original Message- From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of Joe Subich, W4TV Sent: Monday, December 30, 2013 6:05 PM To: topband@contesting.com Subject: Re: Topband: Digital mode spurious issues > Does the Joe Taylor software have a provision for this? No, Joe Taylor's protocols are not capable of operating in LSB. 73, ... Joe, W4TV On 12/30/2013 5:59 PM, Richard (Rick) Karlquist wrote: > The simplest technical solution would be for the digital mode users to > put the radio in LSB mode. > This puts unwanted sideband QRM away from the DX CW window. Does the > Joe Taylor software have a provision for this? > > Rick N6RK > _ > Topband Reflector Archives - http://www.contesting.com/_topband > _ Topband Reflector Archives - http://www.contesting.com/_topband _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Digital mode spurious issues
> Does the Joe Taylor software have a provision for this? No, Joe Taylor's protocols are not capable of operating in LSB. 73, ... Joe, W4TV On 12/30/2013 5:59 PM, Richard (Rick) Karlquist wrote: The simplest technical solution would be for the digital mode users to put the radio in LSB mode. This puts unwanted sideband QRM away from the DX CW window. Does the Joe Taylor software have a provision for this? Rick N6RK _ Topband Reflector Archives - http://www.contesting.com/_topband _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Digital mode spurious issues
The simplest technical solution would be for the digital mode users to put the radio in LSB mode. This puts unwanted sideband QRM away from the DX CW window. Does the Joe Taylor software have a provision for this? Rick N6RK _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Digital mode spurious issues
You're both right -- it is either JT65 or JT9. WSJT software, based on protocols developed by K1JT, will decode both modes. Another software package called JT65-HF will decode only JT65. And yes, the trash Tom was hearing was either overdriven audio or a crummy radio or both. Some of the newer hams using these modes are also using pretty crummy radios -- all-banders in the $900 price range. OTOH, most are running flea power -- 20W is QRO for this crowd. I've done a fair amount of JT65, mostly on 6M and 160M, using my K3. I've also used other K1JT modes designed for meteor scatter (FSK441) and ionospheric scatter (SCAT). JT9 is Joe's latest and greatest protocol, requiring a fraction of the bandwidth of JT65. 73, Jim K9YC On 12/30/2013 10:30 AM, Mike Waters wrote: I believe the mode that operates at 1873-1838 is JT65, and WSJT is needed to decode it. I never tried it. It was developed by K1JT for weak-signal and EME work. http://www.physics.princeton.edu/pulsar/K1JT/wsjt.html A common scenario with digital modes is that the audio into the mic input is too high, causing unwanted spurs. _ Topband Reflector Archives - http://www.contesting.com/_topband
Re: Topband: Digital mode spurious issues
Tom, I believe the mode that operates at 1873-1838 is JT65, and WSJT is needed to decode it. I never tried it. It was developed by K1JT for weak-signal and EME work. http://www.physics.princeton.edu/pulsar/K1JT/wsjt.html A common scenario with digital modes is that the audio into the mic input is too high, causing unwanted spurs. 73, Mike www.w0btu.com On Mon, Dec 30, 2013 at 11:11 AM, Tom W8JI wrote: > ... a digimode station up roughly around 1837 came on with a LSB > "spurious" signal on 1833. His signal was a series of slowly changing > stepped tones. I don't know what mode that was. His unwanted sideband > suppression was about 40 dB, but that was not nearly enough. He was 15 dB > out of noise with his unwanted sideband. > > Does anyone know of a universal software to decode signals? Since the FCC > does not require a CW ID, I think that is the only way to identify > stations. ... > _ Topband Reflector Archives - http://www.contesting.com/_topband
Topband: Digital mode spurious issues
I have not been on the air for a year or so, but decided to get back on. I was listening to a DX station around 1833 when a digimode station up roughly around 1837 came on with a LSB "spurious" signal on 1833. His signal was a series of slowly changing stepped tones. I don't know what mode that was. His unwanted sideband suppression was about 40 dB, but that was not nearly enough. He was 15 dB out of noise with his unwanted sideband. Does anyone know of a universal software to decode signals? Since the FCC does not require a CW ID, I think that is the only way to identify stations. I assume: 1.) Operators are unlikely to accept they have a problem if they are getting good reports on the intentional signal 2.) Some rigs just should not be used for digimodes (this was a sideband suppression issue) 3.) Those who unwisely placed digimode subbands next to popular weak signal areas, especially when sideband selection produces a supurious that falls in weak signal areas, are unlikely to rethink the poor placement or poor advice on selecting sidebands 4.) With a little work to convince them, most digital ops with radio problems would avoid operating 73 Tom _ Topband Reflector Archives - http://www.contesting.com/_topband
