[digitalradio] Re: BPL-Busting Modes/Techniques
Bob N4HY wrote: I recently had a general manager of a large amateur radio organization tell me that if I made it possible to communicate through BPL or in any way mitigated BPL through DSP techniques, I would begin to sing soprano and the GM did not mean falsetto. Hi Bob, That sort of threat would not be very effective against me :) When I originally proposed this subject, digital communications for hams to communicate through BPL interference, some of the higher ups in that organization were none too happy with me, either. This led to a curious interaction with the guy spearheading their BPL interference testing. He told me that what I was talking about was an engineering impossibility and I didn't know what I was talking about. At one of my companies, I designed communication systems that solved much more severe co-channel interference problems than BPL. One of those products, based upon these same principles, received a major technology design award several years ago. I sent him one of the product brochures. I have not heard from him since :) Presently, BPL has literally put some ham operators off the air. Other semiconductor-based EMI sources are having similar effects. Restoring these operators to being on the air again is good for ham radio. It might also put the BPL systems on notice, since they could no longer rely upon their interference effectively silencing hams to alleviate their own weakness of EMI susceptibility to RF ingress. Bonnie KQ6XA Need a Digital mode QSO? Connect to Telnet://cluster.dynalias.org Other areas of interest: The MixW Reflector : http://groups.yahoo.com/group/themixwgroup/ DigiPol: http://groups.yahoo.com/group/Digipol (band plan policy discussion) Yahoo! Groups Links * To visit your group on the web, go to: http://groups.yahoo.com/group/digitalradio/ * Your email settings: Individual Email | Traditional * To change settings online go to: http://groups.yahoo.com/group/digitalradio/join (Yahoo! ID required) * To change settings via email: mailto:[EMAIL PROTECTED] mailto:[EMAIL PROTECTED] * To unsubscribe from this group, send an email to: [EMAIL PROTECTED] * Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
[digitalradio] Re: BPL-Busting Modes/Techniques
The general manager of that organization was not wrong! This discussion is mixing apples and oranges as to what BPL interferes with. Digital techniques can not eliminate the interference at RF that BPL introduces. As I have mentioned before, don't forget the RADIO side of things when advocating digital techniques. It is true that the recovered audio from a digital signal will be free of the BPL noise heard in an analog radio. However, that recovered audio must first be detectable by the radio receiving it. If BPL causes enough RF interference to reduce the signal to noise ratio needed by the digital processing you simply lose the whole signal. No amount of digital processing can recover a signal that is below the required signal to noise ratio. BPL DOES reduce the signal to noise ratio at your radio! To advocate that digital techniques can mitigate BPL interference is simply wrong and can ultimately be harmful to ALL of ham radio. I hope someone at the FCC has not seen this thread and uses it in the future to justify their decision on BPL's harmful interference potential. Ultimately, all digital techniques can really do is eliminate the noise from the audio. Digital techniques and signals can not give you a stronger RF signal. Digital signals CAN NOT REDUCE OR MITIGATE the harmful interference caused at RF nor can they recover the lost signal to noise ratio with the consequent reduction in our ability to operate either analog or digital modes. This is what that general manager is trying to tell you. Please don't treat the radio part of these systems as a simple black box that replaces an ethernet wire! Please do the homework required to understand what happens in your radio at RF both on transmit and receive. In other words, do a little RF engineering in addition to the baseband and digital processing engineering. If this thread is also advocating purchasing new radios and amplifiers that can handle higher transmitting powers in digital modes in order to increase signal to noise ratios, then perhaps that is a solution. However, this again is at RF, not because of the digital techniques used and there will be a substantial cost thereby reducing the popularity of these modes. Jim WA0LYK --- In digitalradio@yahoogroups.com, Robert McGwier [EMAIL PROTECTED] wrote: expeditionradio wrote: BPL-Busting Modes/Techniques --- snip The development of new amateur modes, semi-automated and automated frequency agile systems, advanced ARQ, and various sorts of FEC digital techniques are a possible avenue for amateurs to communicate through the interference caused by BPL. It may not be possible to entirely eliminate all the harmful interference BPL creates, but we need to start planning for mitigation. We need to research and characterize the various types of BPL signals so that we can design modulation and control techniques to compensate for them. I recently had a general manager of a large amateur radio organization tell me that if I made it possible to communicate through BPL or in any way mitigated BPL through DSP techniques, I would begin to sing soprano and the GM did not mean falsetto. Using radio engineering and specially-designed digital signal processing, we can develop BPL-Busting Modes. These new modes and systems could carry any combination of voice/image/text/data. Frequency hopping, spread spectrum, wideband OFDM, multi-PSK, ALE, and MFSK are mode/systems that we could implement immediately in new formats... Unfortunately, hams in USA don't have the freedom within the USA FCC rules to advance some of these yet. We look to hams in other countries to pioneer these new techniques. Any technique that would allow higher rates and near bullet proof performance would necessarily sound a whole lot like noise and would necessarily be fairly wideband and would not work in today's traditional radios but would certainly work in the SDR radios. I am afraid that if I didn't have the general manager alter my singing pitch, the rest of ham radio might. Under USA FCC current Amateur Radio Service rules, we do not have the freedom that other countries have, to take advantage of some of the most useful technologies that could help us to communicate through BPL interference. We are still locked in our technology prison. Hopefully, in the near future, we will have more freedom... with bandwidth-based spectrum management. I say that we can do turbo trellis coded based OFDM that are designed for fading dispersive channels with cochannel interference. One of these years when I have yet another life to give, I am certain I can do it and pound tons of data through. The research in ARQ and the development of ALE should indeed allow us to greatly improve the robustness of our link to effectively use the fancier modulations. 73 Bonnie KQ6XA
Re: [digitalradio] Re: BPL-Busting Modes/Techniques
Please don't treat the radio part of these systems as a simple black box that replaces an ethernet wire! Please do the homework required to understand what happens in your radio at RF both on transmit and receive. In other words, do a little RF engineering in addition to the baseband and digital processing engineering. Jim WA0LYK There is, of course, no magic involved. If I may I will again attempt a layman's perspective. Chaos Theory may work to our advantage here. There is often much order embedded in what appears to be chaos. What *appears* to be an impossibly high signal-to-noise-ratio to an analog system is often overcome by a sharp ear and/or DSP processing. Noise as we generically label it appears to be impossible QRM/QRN chaos unless broken down into component parts. If we have good propagation such that a strong signal *may* be received from the desired source and some irresponsible vendor injects BPL QRM/QRN into the spectrum then we have a known source which may be excluded via RF signal and digital processing. We have nulling technologies to remove some of the RF signal and digital to exclude non-relevant QRM/QRN. If we have poor propagation such that the desired signal would already have trouble getting to our receiver then the added BPL QRM will make a difficult problem more so, perhaps but not necessarily impossible. If our transmission is in known packets and BPL QRM/QRN successfully attacks a packet it is resent until completed. As you noted, if we boost the power level of the transmission we enhance the probability of overcoming the BPL QRM/QRN, but we do so at the price of increased cost and added energy -- which may be a precious commodity in an emergency deployment. We also risk generating our own QRM/QRN to nearby Ham non-Ham gear. What am I missing? -- Thanks! 73, doc, KD4E ... somewhere in FL URL: bibleseven (dot) com Need a Digital mode QSO? Connect to Telnet://cluster.dynalias.org Other areas of interest: The MixW Reflector : http://groups.yahoo.com/group/themixwgroup/ DigiPol: http://groups.yahoo.com/group/Digipol (band plan policy discussion) Yahoo! Groups Links * To visit your group on the web, go to: http://groups.yahoo.com/group/digitalradio/ * Your email settings: Individual Email | Traditional * To change settings online go to: http://groups.yahoo.com/group/digitalradio/join (Yahoo! ID required) * To change settings via email: mailto:[EMAIL PROTECTED] mailto:[EMAIL PROTECTED] * To unsubscribe from this group, send an email to: [EMAIL PROTECTED] * Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
[digitalradio] Re: BPL-Busting Modes/Techniques
Bonnie, Your remarks about this person, and I don't know who it is, are not very convincing. Your award winning design apparently had to do with co-channel interference. This is not the same as on-channel interference that increases the total noise level, which is what BPL interference is. On-channel interference requires different techniques to solve than co-channel interference. Better receivers (roofing filters, increased IM3 capability, etc.) are all answers to co-channel interference, along with higher transmitting power. On-channel interference is a whole different animal. It doesn't do any good to have a receiver with an MDS of -140 dBm, an IM3 @ 2 Khz of 120 dB, and brickwall filtering of 3 kHz when the noise floor is -80 dBm due to BPL and the digital signal you want to copy is at -120 dBm. The only answer to this is higher transmitter power! Perhaps you can provide some concrete data on how a digital signal or digital processing techniques can eliminate the difference in signal level (i.e. signal to noise ratio) between what you're trying to receive and the noise floor at the receiver's antenna? Jim WA0LYK --- In digitalradio@yahoogroups.com, expeditionradio [EMAIL PROTECTED] wrote: Bob N4HY wrote: I recently had a general manager of a large amateur radio organization tell me that if I made it possible to communicate through BPL or in any way mitigated BPL through DSP techniques, I would begin to sing soprano and the GM did not mean falsetto. Hi Bob, That sort of threat would not be very effective against me :) When I originally proposed this subject, digital communications for hams to communicate through BPL interference, some of the higher ups in that organization were none too happy with me, either. This led to a curious interaction with the guy spearheading their BPL interference testing. He told me that what I was talking about was an engineering impossibility and I didn't know what I was talking about. At one of my companies, I designed communication systems that solved much more severe co-channel interference problems than BPL. One of those products, based upon these same principles, received a major technology design award several years ago. I sent him one of the product brochures. I have not heard from him since :) Presently, BPL has literally put some ham operators off the air. Other semiconductor-based EMI sources are having similar effects. Restoring these operators to being on the air again is good for ham radio. It might also put the BPL systems on notice, since they could no longer rely upon their interference effectively silencing hams to alleviate their own weakness of EMI susceptibility to RF ingress. Bonnie KQ6XA Need a Digital mode QSO? Connect to Telnet://cluster.dynalias.org Other areas of interest: The MixW Reflector : http://groups.yahoo.com/group/themixwgroup/ DigiPol: http://groups.yahoo.com/group/Digipol (band plan policy discussion) Yahoo! Groups Links * To visit your group on the web, go to: http://groups.yahoo.com/group/digitalradio/ * Your email settings: Individual Email | Traditional * To change settings online go to: http://groups.yahoo.com/group/digitalradio/join (Yahoo! ID required) * To change settings via email: mailto:[EMAIL PROTECTED] mailto:[EMAIL PROTECTED] * To unsubscribe from this group, send an email to: [EMAIL PROTECTED] * Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
[digitalradio] Re: BPL-Busting Modes/Techniques
I may be wrong but I beleive your theory doesn't assume that the RF energy at your reciever's antenna is not additive. In other words, the signal from the transmitter you want to hear and the interfering signal do not add together. You can only discern the strongest signal. An example is, that if you put a carrier on the air and I receive it at S9 and then someone else puts a carrier on the exact same frequency but it only arrives at S8, I'll never know it is there. Therefore, when you remove the interfering signal, you also remove any possibility of retreiving information from the signal you want to hear. Consequently, you will never have a coherent signal to decode. It will always have missing information. Any other assumption means noise, especially random noise, would not be a problem, and that you could always subtract a signal from it. Every mode I know of, digital or analog, has a minimum signal to noise ratio that is required to decode it. Jim WA0LYK --- In digitalradio@yahoogroups.com, kd4e [EMAIL PROTECTED] wrote: Please don't treat the radio part of these systems as a simple black box that replaces an ethernet wire! Please do the homework required to understand what happens in your radio at RF both on transmit and receive. In other words, do a little RF engineering in addition to the baseband and digital processing engineering. Jim WA0LYK There is, of course, no magic involved. If I may I will again attempt a layman's perspective. Chaos Theory may work to our advantage here. There is often much order embedded in what appears to be chaos. What *appears* to be an impossibly high signal-to-noise-ratio to an analog system is often overcome by a sharp ear and/or DSP processing. Noise as we generically label it appears to be impossible QRM/QRN chaos unless broken down into component parts. If we have good propagation such that a strong signal *may* be received from the desired source and some irresponsible vendor injects BPL QRM/QRN into the spectrum then we have a known source which may be excluded via RF signal and digital processing. We have nulling technologies to remove some of the RF signal and digital to exclude non-relevant QRM/QRN. If we have poor propagation such that the desired signal would already have trouble getting to our receiver then the added BPL QRM will make a difficult problem more so, perhaps but not necessarily impossible. If our transmission is in known packets and BPL QRM/QRN successfully attacks a packet it is resent until completed. As you noted, if we boost the power level of the transmission we enhance the probability of overcoming the BPL QRM/QRN, but we do so at the price of increased cost and added energy -- which may be a precious commodity in an emergency deployment. We also risk generating our own QRM/QRN to nearby Ham non-Ham gear. What am I missing? -- Thanks! 73, doc, KD4E ... somewhere in FL URL: bibleseven (dot) com Need a Digital mode QSO? Connect to Telnet://cluster.dynalias.org Other areas of interest: The MixW Reflector : http://groups.yahoo.com/group/themixwgroup/ DigiPol: http://groups.yahoo.com/group/Digipol (band plan policy discussion) Yahoo! Groups Links * To visit your group on the web, go to: http://groups.yahoo.com/group/digitalradio/ * Your email settings: Individual Email | Traditional * To change settings online go to: http://groups.yahoo.com/group/digitalradio/join (Yahoo! ID required) * To change settings via email: mailto:[EMAIL PROTECTED] mailto:[EMAIL PROTECTED] * To unsubscribe from this group, send an email to: [EMAIL PROTECTED] * Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
Re: [digitalradio] Re: BPL-Busting Modes/Techniques
kd4e wrote: (text snipped) As you noted, if we boost the power level of the transmission we enhance the probability of overcoming the BPL QRM/QRN, but we do so at the price of increased cost and added energy -- which may be a precious commodity in an emergency deployment. We also risk generating our own QRM/QRN to nearby Ham non-Ham gear. What am I missing? tongue_in_cheek That if it is an EMERGENCY situation, don't worry, power lines will be down , and so, there will be no BPL QRM. /tongue_in_cheek -- Thanks! 73, doc, KD4E ... somewhere in FL URL: bibleseven (dot) com 73 de Jose, CO2JA __ XIII Convención Científica de Ingeniería y Arquitectura 28/noviembre al 1/diciembre de 2006 Cujae, Ciudad de la Habana, Cuba http://www.cujae.edu.cu/eventos/convencion Need a Digital mode QSO? Connect to Telnet://cluster.dynalias.org Other areas of interest: The MixW Reflector : http://groups.yahoo.com/group/themixwgroup/ DigiPol: http://groups.yahoo.com/group/Digipol (band plan policy discussion) Yahoo! Groups Links * To visit your group on the web, go to: http://groups.yahoo.com/group/digitalradio/ * Your email settings: Individual Email | Traditional * To change settings online go to: http://groups.yahoo.com/group/digitalradio/join (Yahoo! ID required) * To change settings via email: mailto:[EMAIL PROTECTED] mailto:[EMAIL PROTECTED] * To unsubscribe from this group, send an email to: [EMAIL PROTECTED] * Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
Re: [digitalradio] Re: BPL-Busting Modes/Techniques
not_so_tongue_in_cheek If I am 800 miles away, outside the local disaster and power outage area, and could have provided assistance, but can't hear you through my local BPL QRM, or have given up HF communications all together as the newly required digital BPL busting technologies are too expensive to play with, don't we all lose? /not_so_tongue_in_cheek Erik KI4HMS/7 Jose A. Amador wrote: kd4e wrote: (text snipped) As you noted, if we boost the power level of the transmission we enhance the probability of overcoming the BPL QRM/QRN, but we do so at the price of increased cost and added energy -- which may be a precious commodity in an emergency deployment. We also risk generating our own QRM/QRN to nearby Ham non-Ham gear. What am I missing? tongue_in_cheek That if it is an EMERGENCY situation, don't worry, power lines will be down , and so, there will be no BPL QRM. /tongue_in_cheek -- Thanks! 73, doc, KD4E ... somewhere in FL URL: bibleseven (dot) com 73 de Jose, CO2JA Need a Digital mode QSO? Connect to Telnet://cluster.dynalias.org Other areas of interest: The MixW Reflector : http://groups.yahoo.com/group/themixwgroup/ DigiPol: http://groups.yahoo.com/group/Digipol (band plan policy discussion) Yahoo! Groups Links * To visit your group on the web, go to: http://groups.yahoo.com/group/digitalradio/ * Your email settings: Individual Email | Traditional * To change settings online go to: http://groups.yahoo.com/group/digitalradio/join (Yahoo! ID required) * To change settings via email: mailto:[EMAIL PROTECTED] mailto:[EMAIL PROTECTED] * To unsubscribe from this group, send an email to: [EMAIL PROTECTED] * Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
Re: [digitalradio] Re: BPL-Busting Modes/Techniques
I may be wrong but I beleive your theory doesn't assume that the RF energy at your reciever's antenna is not additive. In other words, the signal from the transmitter you want to hear and the interfering signal do not add together. You can only discern the strongest signal. An example is, that if you put a carrier on the air and I receive it at S9 and then someone else puts a carrier on the exact same frequency but it only arrives at S8, I'll never know it is there. Therefore, when you remove the interfering signal, you also remove any possibility of retreiving information from the signal you want to hear. Consequently, you will never have a coherent signal to decode. It will always have missing information. Any other assumption means noise, especially random noise, would not be a problem, and that you could always subtract a signal from it. Every mode I know of, digital or analog, has a minimum signal to noise ratio that is required to decode it. Jim WA0LYK SSB is carrier suppressed and CW is all carrier. In either case several stations may transmit on the same frequency and I can hear at least pieces of many of them. What you are describing sounds like FM capture effect, I am not certain that it applies to other modes. Digital modes have steadily improved in the capacity to extract data packets from further and further down into the noise floor. In my construct we are dealing with a situation where it is possible to receive a signal in the absence of the BPL QRM/QRN so the non-BPL exacerbated SNR would be at a reasonable level absent the BPL. Since BPL-generated QRM-QRN is somewhat predictable it would seem reasonable to postulate that it may be removed or mitigated via a variety of methods. This is not to say that I believe BPL is anything other than a dumb idea, financially or technologically. It is bad for stockholders, bad for emergency communications, and bad for Hams and SWL's. That said, the level of power line, cable line, private resident, and business QRM/QRN her north of Florida is horrific. It renders the AM-broadcast band nearly unusable in places -- in direct violation of law and regs. Enforcement action is unlikely. One wonders if the hidden agenda of BPL and ignoring other QRM/QRN is to drive Hams off significant segments of spectrum in order to make it available to commercial interests. -- Thanks! 73, doc, KD4E ... somewhere in FL URL: bibleseven (dot) com Need a Digital mode QSO? Connect to Telnet://cluster.dynalias.org Other areas of interest: The MixW Reflector : http://groups.yahoo.com/group/themixwgroup/ DigiPol: http://groups.yahoo.com/group/Digipol (band plan policy discussion) Yahoo! Groups Links * To visit your group on the web, go to: http://groups.yahoo.com/group/digitalradio/ * Your email settings: Individual Email | Traditional * To change settings online go to: http://groups.yahoo.com/group/digitalradio/join (Yahoo! ID required) * To change settings via email: mailto:[EMAIL PROTECTED] mailto:[EMAIL PROTECTED] * To unsubscribe from this group, send an email to: [EMAIL PROTECTED] * Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
Re: [digitalradio] Re: BPL-Busting Modes/Techniques
jgorman01 wrote: Bonnie, Your remarks about this person, and I don't know who it is, are not very convincing. Your award winning design apparently had to do with co-channel interference. This is not the same as on-channel interference that increases the total noise level, which is what BPL interference is. On-channel interference requires different techniques to solve than co-channel interference. Better receivers (roofing filters, increased IM3 capability, etc.) are all answers to co-channel interference, along with higher transmitting power. On-channel interference is a whole different animal. It doesn't do any good to have a receiver with an MDS of -140 dBm, an IM3 @ 2 Khz of 120 dB, and brickwall filtering of 3 kHz when the noise floor is -80 dBm due to BPL and the digital signal you want to copy is at -120 dBm. The only answer to this is higher transmitter power! Perhaps you can provide some concrete data on how a digital signal or digital processing techniques can eliminate the difference in signal level (i.e. signal to noise ratio) between what you're trying to receive and the noise floor at the receiver's antenna? Well, maybe remembering a few things seems to be in order. The SNR you get with digital is mostly what you conceive when you design the system, as on baseband it depends on the quantization noise of the ADC/codecs. If your digitally modulated signal is above a given threshold, the results will be as clean as the baseband quality you defined. You are transmitting NUMBERS (does NUMERIQUE, in french, ring the bell ?? ). Telephone speech aimed at som 50 dB SNR, compact disks aimed at 90+ dB... With digitalyou either get thru with a PERFECT signal, or NONE at all. That is already happenning with ATSC, places that formerly had bad quality reception getting no signal, and places with fair to good signals, get flawless reception. A good example of that is PSTN PCM links. With some 22 db of link SNR you get about 48 dB of speech SNR. If the SNR on the link is higher, nothing happens, you are wasting power. If it is lower than that, the link will be cut. On radio systems you have to keep a wider safety margin than on wired systems, generally. On linear systems, the signal to noise ratio depends directly on the ratios of message to QRM. On exponentially modulated signals, you just have to exceed the capture ratio of the receiver. On digital signals, you get a perfect replica of the baseband sampled signal, after you exceed the threshold. If the signal strength wanders about the threshold, you will get intermittent reception. I am disregarding the effects of lossy compression, which is the price we have to pay for using too narrow channels. On RF digital links, there are other tools to dodge QRM. Maybe, finding notches in the interfering spectrum, or in the temporal periodicity of the interferer. I truly believe we have not seen all there is in the tricks box. A book on DSP can give some further insight. And of course, the RADIO is a link on this chain. And the chain is as strong as the weakest link, as we all know. Digital does things unthinkable on the analog domain. I would suggest you to find and take a look at Communications Systems by A. Bruce Carlson, Fourth edition and refresh a few things. Look for: http://www.powells.com/biblio?isbn=0070111278 or http://www.amazon.com/Communication-Systems-Bruce-Carlson/dp/0070111278 Or maybe in some library close to you that keeps a copy. There are some other authors, like Sklar, Lathi, etc. I am quite familiar with Prof. Carlson books since I was an engineering student, and I have followed his publications after that. Jim WA0LYK Jose, CO2JA __ XIII Convención Científica de Ingeniería y Arquitectura 28/noviembre al 1/diciembre de 2006 Cujae, Ciudad de la Habana, Cuba http://www.cujae.edu.cu/eventos/convencion Need a Digital mode QSO? Connect to Telnet://cluster.dynalias.org Other areas of interest: The MixW Reflector : http://groups.yahoo.com/group/themixwgroup/ DigiPol: http://groups.yahoo.com/group/Digipol (band plan policy discussion) Yahoo! Groups Links * To visit your group on the web, go to: http://groups.yahoo.com/group/digitalradio/ * Your email settings: Individual Email | Traditional * To change settings online go to: http://groups.yahoo.com/group/digitalradio/join (Yahoo! ID required) * To change settings via email: mailto:[EMAIL PROTECTED] mailto:[EMAIL PROTECTED] * To unsubscribe from this group, send an email to: [EMAIL PROTECTED] * Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
Re: [digitalradio] Re: BPL-Busting Modes/Techniques
Certainly. I cannot argue that. I was just joking about what would happen in the affected zone. That's why I emphazised tongue in cheek. I haved NOT been in favor of BPL either, power lines are too leaky, but seems it is something we will have to live with. It is a fat source of revenues for the power companies. Jose, CO2JA list email filter wrote: not_so_tongue_in_cheek If I am 800 miles away, outside the local disaster and power outage area, and could have provided assistance, but can't hear you through my local BPL QRM, or have given up HF communications all together as the newly required digital BPL busting technologies are too expensive to play with, don't we all lose? /not_so_tongue_in_cheek Erik KI4HMS/7 Jose A. Amador wrote: kd4e wrote: (text snipped) As you noted, if we boost the power level of the transmission we enhance the probability of overcoming the BPL QRM/QRN, but we do so at the price of increased cost and added energy -- which may be a precious commodity in an emergency deployment. We also risk generating our own QRM/QRN to nearby Ham non-Ham gear. What am I missing? tongue_in_cheek That if it is an EMERGENCY situation, don't worry, power lines will be down , and so, there will be no BPL QRM. /tongue_in_cheek -- Thanks! 73, doc, KD4E ... somewhere in FL URL: bibleseven (dot) com 73 de Jose, CO2JA __ XIII Convención Científica de Ingeniería y Arquitectura 28/noviembre al 1/diciembre de 2006 Cujae, Ciudad de la Habana, Cuba http://www.cujae.edu.cu/eventos/convencion Need a Digital mode QSO? Connect to Telnet://cluster.dynalias.org Other areas of interest: The MixW Reflector : http://groups.yahoo.com/group/themixwgroup/ DigiPol: http://groups.yahoo.com/group/Digipol (band plan policy discussion) Yahoo! Groups Links * To visit your group on the web, go to: http://groups.yahoo.com/group/digitalradio/ * Your email settings: Individual Email | Traditional * To change settings online go to: http://groups.yahoo.com/group/digitalradio/join (Yahoo! ID required) * To change settings via email: mailto:[EMAIL PROTECTED] mailto:[EMAIL PROTECTED] * To unsubscribe from this group, send an email to: [EMAIL PROTECTED] * Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
Re: [digitalradio] Armstrong 'got Moon quote right'
ORIGINAL MESSAGE: On Mon, 2 Oct 2006 18:52:42 -0400, Andrew O'Brien [EMAIL PROTECTED] wrote: Armstrong 'got Moon quote right' REPLY FOLLOWS Boys and girls, you have just seen a prime example of historical revisionism. Usually it's done with more subtlety, but technology has allowed a more in-your=face approach. After all, who can argue with technology? :-) Bill, W6WRT who is sure this has something to do with digital radio Need a Digital mode QSO? Connect to Telnet://cluster.dynalias.org Other areas of interest: The MixW Reflector : http://groups.yahoo.com/group/themixwgroup/ DigiPol: http://groups.yahoo.com/group/Digipol (band plan policy discussion) Yahoo! Groups Links * To visit your group on the web, go to: http://groups.yahoo.com/group/digitalradio/ * Your email settings: Individual Email | Traditional * To change settings online go to: http://groups.yahoo.com/group/digitalradio/join (Yahoo! ID required) * To change settings via email: mailto:[EMAIL PROTECTED] mailto:[EMAIL PROTECTED] * To unsubscribe from this group, send an email to: [EMAIL PROTECTED] * Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
Re: [digitalradio] Re: BPL-Busting Modes/Techniques
list email filter wrote: not_so_tongue_in_cheek If I am 800 miles away, outside the local disaster and power outage area, and could have provided assistance, but can't hear you through my local BPL QRM, or have given up HF communications all together as the newly required digital BPL busting technologies are too expensive to play with, don't we all lose? /not_so_tongue_in_cheek I feel that it is the responsibility of the software defined radio groups to go forward and provide for these capabilities since it really is the only way. I will not defend this in detail here but I believe it strongly for all sorts of theoretical and practical reasons. 73 Bob N4HY -- AMSAT VP Engineering. Member: ARRL, AMSAT-DL, TAPR, Packrats, NJQRP/AMQRP, QRP ARCI, QCWA, FRC. ARRL SDR Wrk Grp Chairman You see, wire telegraph is a kind of a very, very long cat. You pull his tail in New York and his head is meowing in Los Angeles. Do you understand this? And radio operates exactly the same way: you send signals here, they receive them there. The only difference is that there is no cat. - Einstein Need a Digital mode QSO? Connect to Telnet://cluster.dynalias.org Other areas of interest: The MixW Reflector : http://groups.yahoo.com/group/themixwgroup/ DigiPol: http://groups.yahoo.com/group/Digipol (band plan policy discussion) Yahoo! Groups Links * To visit your group on the web, go to: http://groups.yahoo.com/group/digitalradio/ * Your email settings: Individual Email | Traditional * To change settings online go to: http://groups.yahoo.com/group/digitalradio/join (Yahoo! ID required) * To change settings via email: mailto:[EMAIL PROTECTED] mailto:[EMAIL PROTECTED] * To unsubscribe from this group, send an email to: [EMAIL PROTECTED] * Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
Re: [digitalradio] Re: BPL-Busting Modes/Techniques
jgorman01 wrote: I may be wrong but I beleive your theory doesn't assume that the RF energy at your reciever's antenna is not additive. In other words, the signal from the transmitter you want to hear and the interfering signal do not add together. You can only discern the strongest signal. An example is, that if you put a carrier on the air and I receive it at S9 and then someone else puts a carrier on the exact same frequency but it only arrives at S8, I'll never know it is there. The only kind of receiver that does this by design is one in which a limiter is in the front end (or other undesireable nonlinearity) and exhibits the capture effect (such as FM receivers). So you statement is false. They do add to the extent that the front end and following stages continue to operate linearly. If BPL is very close to you, and the other signal is weak, then it is possible (easy) for the audio difference coming from a typical amateur radio transceiver to exceed the dynamic range OF THE AUDIO CIRCUITS (not the front end or the IF's). For some of the SDR transceivers, where the audio dynamic range is presented digitally to the processing programs (the audio never leaves through a D/A or speaker or wire of any type) through a virtual audio hookup (done with software wires rather than hardware wires). I feel this is one of the major assets of these SDR approaches (SDR-1000, GnuRadio, HPSDR). The other major asset of each of these SDR systems is that they can, or soon will be able to, tune a signal that is almost 200 kHz wide. Therefore, when you remove the interfering signal, you also remove any possibility of retreiving information from the signal you want to hear. Consequently, you will never have a coherent signal to decode. It will always have missing information. There is information degradation but your nonlinearity reason is incorrect insofar as it went. Any other assumption means noise, especially random noise, would not be a problem, and that you could always subtract a signal from it. Every mode I know of, digital or analog, has a minimum signal to noise ratio that is required to decode it. This is correct. BPL is not very noise like in comparison to a very well designed digital system where randomization of the data, forward error correction, source coding (compression) all make the data look flat random. So a system to defeat BPL must be designed to overcome the nonrandom statistics of the BPL excitation. There will be a signal / (noise+interference) ratio beneath which we cannot go further. This is well understood what it is even if it is difficult to compute (with interference being decidely nongaussian and the channel having memory). If you demand 1000 bps from the channel and the capacity is 999 bps, you have exceeded the capacity and information will be lost. Any system that will communicate through BPL interference must degrade gracefully as the channel information capacity decreases. It is the demand for fixed rate where that rate exceeds capacity that leads to a graceless collapse in our HF systems. One of the things the illegal encrypted communications Pactor III does, is decrease the information rate to be below the capacity (any digital system where the complete specifications allowing duplication are not published is a violation of Part 97) to allow for continued communications at the reduced rate. There is no one size fits all with these horrid HF channels. Any system designed to replace what we have will ultimately have to accept this and build for it. Jim WA0LYK Bob N4HY -- AMSAT VP Engineering. Member: ARRL, AMSAT-DL, TAPR, Packrats, NJQRP/AMQRP, QRP ARCI, QCWA, FRC. ARRL SDR Wrk Grp Chairman You see, wire telegraph is a kind of a very, very long cat. You pull his tail in New York and his head is meowing in Los Angeles. Do you understand this? And radio operates exactly the same way: you send signals here, they receive them there. The only difference is that there is no cat. - Einstein Need a Digital mode QSO? Connect to Telnet://cluster.dynalias.org Other areas of interest: The MixW Reflector : http://groups.yahoo.com/group/themixwgroup/ DigiPol: http://groups.yahoo.com/group/Digipol (band plan policy discussion) Yahoo! Groups Links * To visit your group on the web, go to: http://groups.yahoo.com/group/digitalradio/ * Your email settings: Individual Email | Traditional * To change settings online go to: http://groups.yahoo.com/group/digitalradio/join (Yahoo! ID required) * To change settings via email: mailto:[EMAIL PROTECTED] mailto:[EMAIL PROTECTED] * To unsubscribe from this group, send an email to: [EMAIL PROTECTED] * Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
Re: [digitalradio] Re: BPL-Busting Modes/Techniques
The arguments here are understood. For example, I often try very hard to avoid describing an 802.11g Access Point (AP) as a Ethernet Hub without the wires. RF is not that simple. However, I am confident, as Dr. Bob is, that a digital solution to BPL is within our reach. 73, John - K8OCL From: Robert McGwier [EMAIL PROTECTED] Reply-To: digitalradio@yahoogroups.com To: digitalradio@yahoogroups.com Subject: Re: [digitalradio] Re: BPL-Busting Modes/Techniques Date: Tue, 03 Oct 2006 12:31:23 -0400 list email filter wrote: not_so_tongue_in_cheek If I am 800 miles away, outside the local disaster and power outage area, and could have provided assistance, but can't hear you through my local BPL QRM, or have given up HF communications all together as the newly required digital BPL busting technologies are too expensive to play with, don't we all lose? /not_so_tongue_in_cheek I feel that it is the responsibility of the software defined radio groups to go forward and provide for these capabilities since it really is the only way. I will not defend this in detail here but I believe it strongly for all sorts of theoretical and practical reasons. 73 Bob N4HY -- AMSAT VP Engineering. Member: ARRL, AMSAT-DL, TAPR, Packrats, NJQRP/AMQRP, QRP ARCI, QCWA, FRC. ARRL SDR Wrk Grp Chairman You see, wire telegraph is a kind of a very, very long cat. You pull his tail in New York and his head is meowing in Los Angeles. Do you understand this? And radio operates exactly the same way: you send signals here, they receive them there. The only difference is that there is no cat. - Einstein Need a Digital mode QSO? Connect to Telnet://cluster.dynalias.org Other areas of interest: The MixW Reflector : http://groups.yahoo.com/group/themixwgroup/ DigiPol: http://groups.yahoo.com/group/Digipol (band plan policy discussion) Yahoo! Groups Links * To visit your group on the web, go to: http://groups.yahoo.com/group/digitalradio/ * Your email settings: Individual Email | Traditional * To change settings online go to: http://groups.yahoo.com/group/digitalradio/join (Yahoo! ID required) * To change settings via email: mailto:[EMAIL PROTECTED] mailto:[EMAIL PROTECTED] * To unsubscribe from this group, send an email to: [EMAIL PROTECTED] * Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
Re: [digitalradio] Armstrong 'got Moon quote right'
Bill Turner wrote: ORIGINAL MESSAGE: On Mon, 2 Oct 2006 18:52:42 -0400, Andrew O'Brien [EMAIL PROTECTED] wrote: Armstrong 'got Moon quote right' REPLY FOLLOWS Boys and girls, you have just seen a prime example of historical revisionism. Usually it's done with more subtlety, but technology has allowed a more in-your=face approach. After all, who can argue with technology? :-) Bill, W6WRT who is sure this has something to do with digital radio This is more analogous to DNA testing revolutionizing forensics and reversing some (wrong) convictions. A newer technique embodied in an easy to obtain audio processing software package was applied and it basically showed the tail of the impulse response of the comm system to the a. His vox dropped out at just the wrong moment, but you could see the signs of the a having been uttered according to this analysis. It is persuasive and for the sake of one brave men and a great hero , I choose to believe it. Bob -- AMSAT VP Engineering. Member: ARRL, AMSAT-DL, TAPR, Packrats, NJQRP/AMQRP, QRP ARCI, QCWA, FRC. ARRL SDR Wrk Grp Chairman You see, wire telegraph is a kind of a very, very long cat. You pull his tail in New York and his head is meowing in Los Angeles. Do you understand this? And radio operates exactly the same way: you send signals here, they receive them there. The only difference is that there is no cat. - Einstein Need a Digital mode QSO? Connect to Telnet://cluster.dynalias.org Other areas of interest: The MixW Reflector : http://groups.yahoo.com/group/themixwgroup/ DigiPol: http://groups.yahoo.com/group/Digipol (band plan policy discussion) Yahoo! Groups Links * To visit your group on the web, go to: http://groups.yahoo.com/group/digitalradio/ * Your email settings: Individual Email | Traditional * To change settings online go to: http://groups.yahoo.com/group/digitalradio/join (Yahoo! ID required) * To change settings via email: mailto:[EMAIL PROTECTED] mailto:[EMAIL PROTECTED] * To unsubscribe from this group, send an email to: [EMAIL PROTECTED] * Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
[digitalradio] Re: BPL-Busting Modes/Techniques
Jim WA0LYK wrote: Bonnie, your award winning design apparently had to do with co-channel interference. This is not the same as on-channel interference that increases the total noise level, which is what BPL interference is. On-channel interference requires different techniques to solve than co-channel interference. Hi Jim, On-channel as you describe it, is co-channel. But, in fact, the term On-Channel has been coined by HD radio for a system which does not have two signals sharing the same spectrum, so the trademarked term probably should be avoided for clarity. Co-channel means the two signals (desired and undesired), occupy the same channel. In other words, the undesired BPL interference and the desired ham signal share the same chunk of spectrum, in this case: the passband of the ham receiver. The BPL is also transmitting on a much wider area of spectrum, that includes the smaller chunk of spectrum that the ham radio signal occupies. But, whatever you want to call it, in this instance, I am discussing the mitigation of only that portion of the BPL noise that is within the ham receiver's passband. The overall BPL signal may appear as noise to the human ear, but if you look more closely with signal analysis, there are certain qualities of the BPL signal that may be exploited to enable ham radio communications to pass through. I won't go very much further into the techniques at this time, but, the basic principle is that there are holes and fuzzy spaces in frequency/ phase/ time domain of the interfering BPL signal that we can pass ham signals through. I have previously described two digital methods (RMPSK and Olivia 2kHz), that could provide some mitigation for BPL interference. These methods may enable the hams who are presently off the air due to BPL, to at least get back on the air with text-based HF communication. There are other, more complex BPL-busting methods that could be developed for voice and faster data. Even using advanced techniques, there are certainly S/N limitations, but, improvements on the order of 20dB or 30dB may be enough in many cases to enable ham communications in the BPL environment where none existed using conventional methods. There may also be control techniques we can use that are interactive with BPL's ingress-response, or interactive with BPL system loading trends. These techniques require more characterization of the BPL system, and adaptive communication design beyond what we have been discussing so far. Bonnie KQ6XA . Need a Digital mode QSO? Connect to Telnet://cluster.dynalias.org Other areas of interest: The MixW Reflector : http://groups.yahoo.com/group/themixwgroup/ DigiPol: http://groups.yahoo.com/group/Digipol (band plan policy discussion) Yahoo! Groups Links * To visit your group on the web, go to: http://groups.yahoo.com/group/digitalradio/ * Your email settings: Individual Email | Traditional * To change settings online go to: http://groups.yahoo.com/group/digitalradio/join (Yahoo! ID required) * To change settings via email: mailto:[EMAIL PROTECTED] mailto:[EMAIL PROTECTED] * To unsubscribe from this group, send an email to: [EMAIL PROTECTED] * Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
[digitalradio] Concerning Signal Detection
My uncle, Charles Sumner Williams (author of Introduction to the Optical Transfer Function), who taught radio at Scott Field during WWII and retired from TI said that the problem with computer signal detection (we were discussing CW) was trying to duplicate with a computer what the human brain could do was difficult. However, once you succeeds, the computer is likely to be able to do the job better. I did not realize until much later, that in part he was talking about how our brain, perhaps acting as a quantum like computer, takes current and past information to predict the future and that the brain can be trained to reject certain sounds, patterns and the like. Mathematics remains the fundamental science used to analyze and explain the complex algorithms of human speech. Virtually every branch of pure and applied mathematics has proved to be useful in these efforts. Where the human brain is a biological computer, the computers humans build simply tries to emulate this function...the human brain is our basis and model. Understanding this concept will greatly enhance our ability to create a better HF modem. Walt/K5YFW Need a Digital mode QSO? Connect to Telnet://cluster.dynalias.org Other areas of interest: The MixW Reflector : http://groups.yahoo.com/group/themixwgroup/ DigiPol: http://groups.yahoo.com/group/Digipol (band plan policy discussion) Yahoo! Groups Links * To visit your group on the web, go to: http://groups.yahoo.com/group/digitalradio/ * Your email settings: Individual Email | Traditional * To change settings online go to: http://groups.yahoo.com/group/digitalradio/join (Yahoo! ID required) * To change settings via email: mailto:[EMAIL PROTECTED] mailto:[EMAIL PROTECTED] * To unsubscribe from this group, send an email to: [EMAIL PROTECTED] * Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
[digitalradio] Digital voice with K0PFX
All: Copied K0PFX this afternoon on 20 meter digital voice using WinDRM. Took a while to get the files in order, but all is working thanks to Mel. I have the reocrding if anyone would like to hear it. 73 Tony KT2Q Need a Digital mode QSO? Connect to Telnet://cluster.dynalias.org Other areas of interest: The MixW Reflector : http://groups.yahoo.com/group/themixwgroup/ DigiPol: http://groups.yahoo.com/group/Digipol (band plan policy discussion) Yahoo! Groups Links * To visit your group on the web, go to: http://groups.yahoo.com/group/digitalradio/ * Your email settings: Individual Email | Traditional * To change settings online go to: http://groups.yahoo.com/group/digitalradio/join (Yahoo! ID required) * To change settings via email: mailto:[EMAIL PROTECTED] mailto:[EMAIL PROTECTED] * To unsubscribe from this group, send an email to: [EMAIL PROTECTED] * Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
[digitalradio] Mysterious Radio Hiss Blamed on Space Weather
From SPACE.com Mysterious Radio Hiss Blamed on Space Weather, Full story at: http://www.space.com/scienceastronomy/061003_science_tuesday.html Jerry - K0HZI Need a Digital mode QSO? Connect to Telnet://cluster.dynalias.org Other areas of interest: The MixW Reflector : http://groups.yahoo.com/group/themixwgroup/ DigiPol: http://groups.yahoo.com/group/Digipol (band plan policy discussion) Yahoo! Groups Links * To visit your group on the web, go to: http://groups.yahoo.com/group/digitalradio/ * Your email settings: Individual Email | Traditional * To change settings online go to: http://groups.yahoo.com/group/digitalradio/join (Yahoo! ID required) * To change settings via email: mailto:[EMAIL PROTECTED] mailto:[EMAIL PROTECTED] * To unsubscribe from this group, send an email to: [EMAIL PROTECTED] * Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
[digitalradio] Re: HF Digital Voice
Does Digital Voice files work the same as the image files that are sent on 14.233? In other words one needs a good solid signal in order to copy and decode the Digital Voice files? The way 20 meters has been at my QTH most of the summer, I would still be trying to decode the first Digital Voice file, HI. Have only copied two or three image files using HamPal, all others I get to many errors and don't want to spend half a day trying for good fills. Jerry - K0HZI Need a Digital mode QSO? Connect to Telnet://cluster.dynalias.org Other areas of interest: The MixW Reflector : http://groups.yahoo.com/group/themixwgroup/ DigiPol: http://groups.yahoo.com/group/Digipol (band plan policy discussion) Yahoo! Groups Links * To visit your group on the web, go to: http://groups.yahoo.com/group/digitalradio/ * Your email settings: Individual Email | Traditional * To change settings online go to: http://groups.yahoo.com/group/digitalradio/join (Yahoo! ID required) * To change settings via email: mailto:[EMAIL PROTECTED] mailto:[EMAIL PROTECTED] * To unsubscribe from this group, send an email to: [EMAIL PROTECTED] * Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
Re: [digitalradio] Re: BPL-Busting Modes/Techniques
Jerry, Probably the better way to look at it is that co-channel interference is on the same channel, and adjacent channel interference is immediately next to the signal you want. We have some pretty good interference fighting technology in today's amateur equipment. Although some are claiming that digital HF voice is going to be successful, I have serious doubts about it the more I find out. Most of the digital signals that require very large throughput, which would include voice, tend to require some very good S/N ratios in order to work. For example, you might be able to send some slow digital messages on a very weak signal that has other ionospheric disturbances using Olivia or MFSK16, etc. While the throughput is relatively slow, you may be able to get this information from the TX to the RX. With the need to send more information, and therefore the need for a better S/N ratio, you just are not going to ever be able to do well with voice. At this point, a number of hams moved from RDFT to QAM OFDM for SSTV and from what they tell me, it is mostly because the latter works better and faster. But it still requires close to a 10 db S/N ratio and that means a very good signal in order to get any throughput at all. While we can not repeal the laws of physics, Shannon's Law, etc., we can only get a certain amount of throughput through a given bandwidth of signal. Wider bandwidth could possibly help, but with the expected restrictions on HF bandwidth, it will be much more difficult to come up with modes that can increase the data flow based on BW. 73, Rick, KV9U jgorman01 wrote: This is not the same as on-channel interference that increases the total noise level, which is what BPL interference is. On-channel interference requires different techniques to solve than co-channel interference. Better receivers (roofing filters, increased IM3 capability, etc.) are all answers to co-channel interference, along with higher transmitting power. On-channel interference is a whole different animal. It doesn't do any good to have a receiver with an MDS of -140 dBm, an IM3 @ 2 Khz of 120 dB, and brickwall filtering of 3 kHz when the noise floor is -80 dBm due to BPL and the digital signal you want to copy is at -120 dBm. The only answer to this is higher transmitter power! Perhaps you can provide some concrete data on how a digital signal or digital processing techniques can eliminate the difference in signal level (i.e. signal to noise ratio) between what you're trying to receive and the noise floor at the receiver's antenna? Jim WA0LYK Need a Digital mode QSO? Connect to Telnet://cluster.dynalias.org Other areas of interest: The MixW Reflector : http://groups.yahoo.com/group/themixwgroup/ DigiPol: http://groups.yahoo.com/group/Digipol (band plan policy discussion) Yahoo! Groups Links * To visit your group on the web, go to: http://groups.yahoo.com/group/digitalradio/ * Your email settings: Individual Email | Traditional * To change settings online go to: http://groups.yahoo.com/group/digitalradio/join (Yahoo! ID required) * To change settings via email: mailto:[EMAIL PROTECTED] mailto:[EMAIL PROTECTED] * To unsubscribe from this group, send an email to: [EMAIL PROTECTED] * Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
Re: [digitalradio] Re: BPL-Busting Modes/Techniques
jgorman01 wrote: I may be wrong but I beleive your theory doesn't assume that the RF energy at your reciever's antenna is not additive. In other words, the signal from the transmitter you want to hear and the interfering signal do not add together. Do you mean that superposition theorem does not apply? You are wrong, Jim. You can only discern the strongest signal. In psychoacoustics, that's called masking, if both signals are close, but on different frequencies. An example is, that if you put a carrier on the air and I receive it at S9 and then someone else puts a carrier on the exact same frequency but it only arrives at S8, I'll never know it is there. It is not the case. Two coherent signals, one 6 dB weaker than the other, when added up give rise to a signal 0.972 dB stronger than the stronger one. You may not perceive it, but it does not deny the superposition theorem. I doubt they can add up coherently from two separate VFO's (unless you have two GPS locked DDS's) ...you would get a very low frequency beat, and if it is below 20 Hz (or your audio's low frequency cutoff), you will see the S meter dancing, and hear nothing at all. I used to calibrate my crystal calibrators that way. Therefore, when you remove the interfering signal, you also remove any possibility of retreiving information from the signal you want to hear. ??? Consequently, you will never have a coherent signal to decode. It will always have missing information. What information does an umodulated carrier carry ? Any other assumption means noise, especially random noise, would not be a problem, and that you could always subtract a signal from it. Every mode I know of, digital or analog, has a minimum signal to noise ratio that is required to decode it. Analog signals do not need to be decoded, are they just perceived. Maybe you can specify a certain minimum SNR for comfort, that's all. Jim WA0LYK __ XIII Convención Científica de Ingeniería y Arquitectura 28/noviembre al 1/diciembre de 2006 Cujae, Ciudad de la Habana, Cuba http://www.cujae.edu.cu/eventos/convencion Need a Digital mode QSO? Connect to Telnet://cluster.dynalias.org Other areas of interest: The MixW Reflector : http://groups.yahoo.com/group/themixwgroup/ DigiPol: http://groups.yahoo.com/group/Digipol (band plan policy discussion) Yahoo! Groups Links * To visit your group on the web, go to: http://groups.yahoo.com/group/digitalradio/ * Your email settings: Individual Email | Traditional * To change settings online go to: http://groups.yahoo.com/group/digitalradio/join (Yahoo! ID required) * To change settings via email: mailto:[EMAIL PROTECTED] mailto:[EMAIL PROTECTED] * To unsubscribe from this group, send an email to: [EMAIL PROTECTED] * Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
[digitalradio] TARA PSK Ruble is this weekend - 0000 to 2400 UTC 7 Oct 06
Here is the rules page http://www.n2ty.org/seasons/tara_rumble_rules.html I look forward to seeing some of you. Scotty W7PSK Need a Digital mode QSO? Connect to Telnet://cluster.dynalias.org Other areas of interest: The MixW Reflector : http://groups.yahoo.com/group/themixwgroup/ DigiPol: http://groups.yahoo.com/group/Digipol (band plan policy discussion) Yahoo! Groups Links * To visit your group on the web, go to: http://groups.yahoo.com/group/digitalradio/ * Your email settings: Individual Email | Traditional * To change settings online go to: http://groups.yahoo.com/group/digitalradio/join (Yahoo! ID required) * To change settings via email: mailto:[EMAIL PROTECTED] mailto:[EMAIL PROTECTED] * To unsubscribe from this group, send an email to: [EMAIL PROTECTED] * Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
[digitalradio] Digital Modes: How will the DSTAR vs 10F3 Conflict be resolved?
Any plans for D-STAR 10F3 Conflict Resolution? Alinco uses the 10F3 digital mode, Icom D-Star, they apparently do not intercommunicate. Anyone aware of an adaptive interface between them? Any idea what Kenwood and Yaesu will do? To the degree to which digital voice and digital data via 2/440 gear becomes more common it sure would be nice to not invest in likely-to-be- orphaned gear! An Alinco with 10F3 is radically less costly than an equivalent Icom 2/440 with D-Star, a difference of $300. The mono-band Icom handhelds require a $189. option to access D-Star. Odd way to market a new technology! Icom seems to be working hard to promote D-STAR, are any major emergency response organizations buying-in or are they waiting for this latest VHS vs BETA technology debate to work itself out? -- Thanks! 73, doc, KD4E ... somewhere in FL URL: bibleseven (dot) com Need a Digital mode QSO? Connect to Telnet://cluster.dynalias.org Other areas of interest: The MixW Reflector : http://groups.yahoo.com/group/themixwgroup/ DigiPol: http://groups.yahoo.com/group/Digipol (band plan policy discussion) Yahoo! Groups Links * To visit your group on the web, go to: http://groups.yahoo.com/group/digitalradio/ * Your email settings: Individual Email | Traditional * To change settings online go to: http://groups.yahoo.com/group/digitalradio/join (Yahoo! ID required) * To change settings via email: mailto:[EMAIL PROTECTED] mailto:[EMAIL PROTECTED] * To unsubscribe from this group, send an email to: [EMAIL PROTECTED] * Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
[digitalradio] Re: BPL-Busting Modes/Techniques
Your basically talking about signals you can hear well, i.e. well beyond the minimum signal to noise ratio's. Also with analog SSB voice the crest factor is very large. That is, one person is just speaking a hard consonant while anothers voice is just fading to nothing. Therefore the power inpinging on your antenna varies widely depending whose voice is causing the most power output at any given instant. Even though the BPL signal may be somewhat predictable it will still mask the signal you are looking for. You can not recover what is lost. You may miss the start of a pulse, the end of a pulse, or even a whole pulse. Random noise is not at a constant level even though your ears may think so, that is why the corrections of signals work. However, if the signal is far enough down so that it doesn't even reach the valleys in the noise, then there is no signal present to be retrieved. Haven't you ever heard a signal being suddenly and totally masked by QRN/QRM? I don't mean just hard to hear but when your trying to copy an S2 signal and someone tunes up with a 60 over S9 carrier? There is no way to ever recover the information lost, it just isn't there. Jim WA0LYK --- In digitalradio@yahoogroups.com, kd4e [EMAIL PROTECTED] wrote: I may be wrong but I beleive your theory doesn't assume that the RF energy at your reciever's antenna is not additive. In other words, the signal from the transmitter you want to hear and the interfering signal do not add together. You can only discern the strongest signal. An example is, that if you put a carrier on the air and I receive it at S9 and then someone else puts a carrier on the exact same frequency but it only arrives at S8, I'll never know it is there. Therefore, when you remove the interfering signal, you also remove any possibility of retreiving information from the signal you want to hear. Consequently, you will never have a coherent signal to decode. It will always have missing information. Any other assumption means noise, especially random noise, would not be a problem, and that you could always subtract a signal from it. Every mode I know of, digital or analog, has a minimum signal to noise ratio that is required to decode it. Jim WA0LYK SSB is carrier suppressed and CW is all carrier. In either case several stations may transmit on the same frequency and I can hear at least pieces of many of them. What you are describing sounds like FM capture effect, I am not certain that it applies to other modes. Digital modes have steadily improved in the capacity to extract data packets from further and further down into the noise floor. In my construct we are dealing with a situation where it is possible to receive a signal in the absence of the BPL QRM/QRN so the non-BPL exacerbated SNR would be at a reasonable level absent the BPL. Since BPL-generated QRM-QRN is somewhat predictable it would seem reasonable to postulate that it may be removed or mitigated via a variety of methods. This is not to say that I believe BPL is anything other than a dumb idea, financially or technologically. It is bad for stockholders, bad for emergency communications, and bad for Hams and SWL's. That said, the level of power line, cable line, private resident, and business QRM/QRN her north of Florida is horrific. It renders the AM-broadcast band nearly unusable in places -- in direct violation of law and regs. Enforcement action is unlikely. One wonders if the hidden agenda of BPL and ignoring other QRM/QRN is to drive Hams off significant segments of spectrum in order to make it available to commercial interests. -- Thanks! 73, doc, KD4E ... somewhere in FL URL: bibleseven (dot) com Need a Digital mode QSO? Connect to Telnet://cluster.dynalias.org Other areas of interest: The MixW Reflector : http://groups.yahoo.com/group/themixwgroup/ DigiPol: http://groups.yahoo.com/group/Digipol (band plan policy discussion) Yahoo! Groups Links * To visit your group on the web, go to: http://groups.yahoo.com/group/digitalradio/ * Your email settings: Individual Email | Traditional * To change settings online go to: http://groups.yahoo.com/group/digitalradio/join (Yahoo! ID required) * To change settings via email: mailto:[EMAIL PROTECTED] mailto:[EMAIL PROTECTED] * To unsubscribe from this group, send an email to: [EMAIL PROTECTED] * Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
[digitalradio] Re: BPL-Busting Modes/Techniques
--- In digitalradio@yahoogroups.com, Jose A. Amador [EMAIL PROTECTED] wrote: jgorman01 wrote: Bonnie, Your remarks about this person, and I don't know who it is, are not very convincing. Your award winning design apparently had to do with co-channel interference. This is not the same as on-channel interference that increases the total noise level, which is what BPL interference is. On-channel interference requires different techniques to solve than co-channel interference. Better receivers (roofing filters, increased IM3 capability, etc.) are all answers to co-channel interference, along with higher transmitting power. On-channel interference is a whole different animal. It doesn't do any good to have a receiver with an MDS of -140 dBm, an IM3 @ 2 Khz of 120 dB, and brickwall filtering of 3 kHz when the noise floor is -80 dBm due to BPL and the digital signal you want to copy is at -120 dBm. The only answer to this is higher transmitter power! Perhaps you can provide some concrete data on how a digital signal or digital processing techniques can eliminate the difference in signal level (i.e. signal to noise ratio) between what you're trying to receive and the noise floor at the receiver's antenna? Well, maybe remembering a few things seems to be in order. The SNR you get with digital is mostly what you conceive when you design the system, as on baseband it depends on the quantization noise of the ADC/codecs. If your digitally modulated signal is above a given threshold, the results will be as clean as the baseband quality you defined. You are transmitting NUMBERS (does NUMERIQUE, in french, ring the bell ?? ). Telephone speech aimed at som 50 dB SNR, compact disks aimed at 90+ dB... With digitalyou either get thru with a PERFECT signal, or NONE at all. I am not sure what you are saying here. You seem to be confusing audio dynamic range with the RF SNR a radio needs to extract information. In audio the SNR has more to do with the number of bits used to encode amplitude and the sampling rate. Not the same issue when dealing with RF SNR. That is already happenning with ATSC, places that formerly had bad quality reception getting no signal, and places with fair to good signals, get flawless reception. A good example of that is PSTN PCM links. With some 22 db of link SNR you get about 48 dB of speech SNR. If the SNR on the link is higher, nothing happens, you are wasting power. If it is lower than that, the link will be cut. On radio systems you have to keep a wider safety margin than on wired systems, generally. Again, I think you are confusing audio and RF SNR. The link SNR describes how well the signal can be extracted while the audio SNR describes the encoding properties of the speech. Granted an RF link where the signal is below the SNR threshold will introduce noise, but this is because of loss of information, not noise in the encoded data. On linear systems, the signal to noise ratio depends directly on the ratios of message to QRM. On exponentially modulated signals, you just have to exceed the capture ratio of the receiver. On digital signals, you get a perfect replica of the baseband sampled signal, after you exceed the threshold. If the signal strength wanders about the threshold, you will get intermittent reception. I am disregarding the effects of lossy compression, which is the price we have to pay for using too narrow channels. On RF digital links, there are other tools to dodge QRM. Maybe, finding notches in the interfering spectrum, or in the temporal periodicity of the interferer. I truly believe we have not seen all there is in the tricks box. A book on DSP can give some further insight. Think about what your saying here. Amateur radio is going to become a step-child of BPL, looking for notches in the BPL signal to operate in. In addtion, what was recommended was trashing all current radios and moving to wide band capable ones. Are you ready to put all your analog radios in storage, and tell every other ham in the US that they will have to do the same, and fork over multi-thousands of dollars for new, more capable radios all because we are going total digital? And of course, the RADIO is a link on this chain. And the chain is as strong as the weakest link, as we all know. Digital does things unthinkable on the analog domain. I would suggest you to find and take a look at Communications Systems by A. Bruce Carlson, Fourth edition and refresh a few things. Look for: http://www.powells.com/biblio?isbn=0070111278 or http://www.amazon.com/Communication-Systems-Bruce-Carlson/dp/0070111278 Or maybe in some library close to you that keeps a copy. There are some other authors, like Sklar, Lathi, etc. I am quite familiar with Prof. Carlson books since I was an engineering student, and I have followed his
Re: [digitalradio] Digital voice with K0PFX
Good work Tony. I would like to hear the recording. What was the SNR? Andy K3UK - Original Message - From: Tony To: digitalradio@yahoogroups.com Sent: Tuesday, October 03, 2006 2:10 PM Subject: [digitalradio] Digital voice with K0PFX All:Copied K0PFX this afternoon on 20 meter digital voice using WinDRM. Took a while to get the files in order, but all is working thanks to Mel.I have the reocrding if anyone would like to hear it.73 Tony KT2Q __._,_.___ Need a Digital mode QSO? Connect to Telnet://cluster.dynalias.org Other areas of interest: The MixW Reflector : http://groups.yahoo.com/group/themixwgroup/ DigiPol: http://groups.yahoo.com/group/Digipol (band plan policy discussion) SPONSORED LINKS Hobby photography Hobby toy Ham radio Ham radio antenna Ham radio sales Your email settings: Individual Email|Traditional Change settings via the Web (Yahoo! ID required) Change settings via email: Switch delivery to Daily Digest | Switch to Fully Featured Visit Your Group | Yahoo! Groups Terms of Use | Unsubscribe __,_._,___
[digitalradio] Re: TARA PSK Ruble is this weekend - 0000 to 2400 UTC 7 Oct 06
I can find the exchange rate for the Russian Ruble. What is it for a PSK Ruble? Hi Hi! Alan WA4SCA Need a Digital mode QSO? Connect to Telnet://cluster.dynalias.org Other areas of interest: The MixW Reflector : http://groups.yahoo.com/group/themixwgroup/ DigiPol: http://groups.yahoo.com/group/Digipol (band plan policy discussion) Yahoo! Groups Links * To visit your group on the web, go to: http://groups.yahoo.com/group/digitalradio/ * Your email settings: Individual Email | Traditional * To change settings online go to: http://groups.yahoo.com/group/digitalradio/join (Yahoo! ID required) * To change settings via email: mailto:[EMAIL PROTECTED] mailto:[EMAIL PROTECTED] * To unsubscribe from this group, send an email to: [EMAIL PROTECTED] * Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
[digitalradio] Re: BPL-Busting Modes/Techniques
I have done the same thing to calibrate my vfo's. But remember, when you are right on frequency, there is nothing to indicate that there is another signal there. And, I'll be honest, I've never seen my s-meter add the two signals together which would indicate that the powers are being added in the receiver. I have had to reduce the vfo signal to keep it from overriding WWV which is kind of my point. In fact, I just did this using my RF generator. WWV at 5 Mhz is about 10 over S9. The generator is at about S5 with no antenna connected and the lead just resting on top of the transceiver. When I switch the generator on, the S-meter moves not a bit. You would expect it to jump considerably if the RF signals were being added together. Jim WA0LYK --- In digitalradio@yahoogroups.com, Jose A. Amador [EMAIL PROTECTED] wrote: jgorman01 wrote: I may be wrong but I beleive your theory doesn't assume that the RF energy at your reciever's antenna is not additive. In other words, the signal from the transmitter you want to hear and the interfering signal do not add together. Do you mean that superposition theorem does not apply? You are wrong, Jim. You can only discern the strongest signal. In psychoacoustics, that's called masking, if both signals are close, but on different frequencies. An example is, that if you put a carrier on the air and I receive it at S9 and then someone else puts a carrier on the exact same frequency but it only arrives at S8, I'll never know it is there. It is not the case. Two coherent signals, one 6 dB weaker than the other, when added up give rise to a signal 0.972 dB stronger than the stronger one. You may not perceive it, but it does not deny the superposition theorem. I doubt they can add up coherently from two separate VFO's (unless you have two GPS locked DDS's) ...you would get a very low frequency beat, and if it is below 20 Hz (or your audio's low frequency cutoff), you will see the S meter dancing, and hear nothing at all. I used to calibrate my crystal calibrators that way. Therefore, when you remove the interfering signal, you also remove any possibility of retreiving information from the signal you want to hear. ??? Consequently, you will never have a coherent signal to decode. It will always have missing information. What information does an umodulated carrier carry ? Any other assumption means noise, especially random noise, would not be a problem, and that you could always subtract a signal from it. Every mode I know of, digital or analog, has a minimum signal to noise ratio that is required to decode it. Analog signals do not need to be decoded, are they just perceived. Maybe you can specify a certain minimum SNR for comfort, that's all. Jim WA0LYK __ XIII Convención Científica de Ingeniería y Arquitectura 28/noviembre al 1/diciembre de 2006 Cujae, Ciudad de la Habana, Cuba http://www.cujae.edu.cu/eventos/convencion Need a Digital mode QSO? Connect to Telnet://cluster.dynalias.org Other areas of interest: The MixW Reflector : http://groups.yahoo.com/group/themixwgroup/ DigiPol: http://groups.yahoo.com/group/Digipol (band plan policy discussion) Yahoo! Groups Links * To visit your group on the web, go to: http://groups.yahoo.com/group/digitalradio/ * Your email settings: Individual Email | Traditional * To change settings online go to: http://groups.yahoo.com/group/digitalradio/join (Yahoo! ID required) * To change settings via email: mailto:[EMAIL PROTECTED] mailto:[EMAIL PROTECTED] * To unsubscribe from this group, send an email to: [EMAIL PROTECTED] * Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
[digitalradio] Re: BPL-Busting Modes/Techniques
jgorman01 writes: just did this using my RF generator. WWV at 5 Mhz is about 10 over S9. The generator is at about S5 with no antenna connected and the lead just resting on top of the transceiver. When I switch the generator on, the S-meter moves not a bit. You would expect it to jump considerably if the RF signals were being added together. If the S-meter calibration is the classic 6 dBs per S-number, the ratio between S5 and S9+10dB is 34 dB, or a factor of more than 2500:1. 1 uW added to 25 mW, for example, should not be expected to make a visible difference in a meter reading. 73 de KW6H, ex AE6VW -- Chris Jewell [EMAIL PROTECTED] Gualala CA USA 95445 Need a Digital mode QSO? Connect to Telnet://cluster.dynalias.org Other areas of interest: The MixW Reflector : http://groups.yahoo.com/group/themixwgroup/ DigiPol: http://groups.yahoo.com/group/Digipol (band plan policy discussion) Yahoo! Groups Links * To visit your group on the web, go to: http://groups.yahoo.com/group/digitalradio/ * Your email settings: Individual Email | Traditional * To change settings online go to: http://groups.yahoo.com/group/digitalradio/join (Yahoo! ID required) * To change settings via email: mailto:[EMAIL PROTECTED] mailto:[EMAIL PROTECTED] * To unsubscribe from this group, send an email to: [EMAIL PROTECTED] * Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
[digitalradio] New Team Joins the Rumble
Howdy! I'd like to shed so good news with you. I've learned today that we have a "NEW" PSK Team that has tossed their hat into the ring for the upcoming TARA "Rumble" on 7th October 2006. This new team is call The Global PSK Net Team and here is their team line up: Eric, K9VICLudek, OK1VSLScotty, W7PSKSteve, ZC4LIRob, ZL3RG There still is team for a few more teams to come join the fun and give the Global PSK Net Team and run for the Gold! If you and your buddies would like to join the Team Challenge go to TARA's web site for a complete set of the rules. http://www.n2ty.org/seasons/tara_rumble_rules.html FOR ALL TEAMS READ THIS CAREFULLY: Each team must declare its name or ID and each of its members names and callsigns, at least 24 hours before contest kickoff. You can add and drop members from the Team up until this dead line. Then the Teams will be frozen. These declarations will be posted on the Results web page along with the teams other declarations.The team Gaffer can throw a challenge to another team indicating that they will whip em! Royally in the contest. If accepted by the other team, this challenge will be posted in the team's declaration on the Results web page. The winning team will add 100 points to its total and the loosing team subtracts100 points. A maximum of 5 teams can be challenged by a single team for a total of +/- 500 whip em! points on the final score. Once the challenge is declared, if the challenged team declines, that challenge cannot be used again so think carefully before challenging :) Has any team tossed out a "whip em!" challenge yet? It could gain your team a lot of extra points. 73 de NY2U Bill __._,_.___ Need a Digital mode QSO? Connect to Telnet://cluster.dynalias.org Other areas of interest: The MixW Reflector : http://groups.yahoo.com/group/themixwgroup/ DigiPol: http://groups.yahoo.com/group/Digipol (band plan policy discussion) SPONSORED LINKS Hobby photography Hobby toy Ham radio Ham radio antenna Ham radio sales Your email settings: Individual Email|Traditional Change settings via the Web (Yahoo! ID required) Change settings via email: Switch delivery to Daily Digest | Switch to Fully Featured Visit Your Group | Yahoo! Groups Terms of Use | Unsubscribe __,_._,___
Re: [digitalradio] Concerning Signal Detection
DuBose Walt Civ AETC CONS/LGCA wrote: My uncle, Charles Sumner Williams (author of Introduction to the Optical Transfer Function), who taught radio at Scott Field during WWII and retired from TI said that the problem with computer signal detection (we were discussing CW) was trying to duplicate with a computer what the human brain could do was difficult. However, once you succeeds, the computer is likely to be able to do the job better. I did not realize until much later, that in part he was talking about how our brain, perhaps acting as a quantum like computer, takes current and past information to predict the future and that the brain can be trained to reject certain sounds, patterns and the like. I believe this is correct. You cannot do this job correctly and only treat it as a conventional signal processing problem. FEC works on digital signals by building in redundancy. Better decoding of CW would make use of the existing redundancy rather than just is it on or off?. CW sending words clearly has significant Markovity in the actual transmitted tones. To not take advantage of the predictability of the next character or element given those elements just preceding it would be folly. In the case of distorted signal or signal in noise or interference, this is a Hidden Markov process. The algorithms for treating this under certain assumptions are well known and understood. iNTUITIVELY, one looks at the possible outcomes for the next element and picks the best outcome given the observations. One should use signal before AND after current element under consideration as the observations. The brain certainly uses this. I struggled like mad when I was attempting to learn to copy faster morse before I got my extra in the early 1970's. My speed really took off when I relaxed, allowed myself to fall a little bit behind. Now it is clear I am using signal information before and after the object I am attempting to decode. Then the speed really went up when I started copying words and phrases and not letters. Mathematics remains the fundamental science used to analyze and explain the complex algorithms of human speech. Virtually every branch of pure and applied mathematics has proved to be useful in these efforts. Where the human brain is a biological computer, the computers humans build simply tries to emulate this function...the human brain is our basis and model. Understanding this concept will greatly enhance our ability to create a better HF modem. Walt/K5YFW The mathematics of this kind of language modeling applied to signal processing is simply fascinating. 73's Bob N4HY -- AMSAT VP Engineering. Member: ARRL, AMSAT-DL, TAPR, Packrats, NJQRP/AMQRP, QRP ARCI, QCWA, FRC. ARRL SDR Wrk Grp Chairman You see, wire telegraph is a kind of a very, very long cat. You pull his tail in New York and his head is meowing in Los Angeles. Do you understand this? And radio operates exactly the same way: you send signals here, they receive them there. The only difference is that there is no cat. - Einstein Need a Digital mode QSO? Connect to Telnet://cluster.dynalias.org Other areas of interest: The MixW Reflector : http://groups.yahoo.com/group/themixwgroup/ DigiPol: http://groups.yahoo.com/group/Digipol (band plan policy discussion) Yahoo! Groups Links * To visit your group on the web, go to: http://groups.yahoo.com/group/digitalradio/ * Your email settings: Individual Email | Traditional * To change settings online go to: http://groups.yahoo.com/group/digitalradio/join (Yahoo! ID required) * To change settings via email: mailto:[EMAIL PROTECTED] mailto:[EMAIL PROTECTED] * To unsubscribe from this group, send an email to: [EMAIL PROTECTED] * Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
[digitalradio] W1MNK 11-1
1 and 2, I have sent email to my section manager to find a emcomm contact. I'll update when possible. 3. Suppose that during an emergency activation, you find yourself to be the leader of the local emcomm group. To which agency would you report? To whom within the agency would you report? What would your duties be as leader of the emcomm group? Report to the logistics director of the first responding agency. Co-ordinate all communications activities. Need a Digital mode QSO? Connect to Telnet://cluster.dynalias.org Other areas of interest: The MixW Reflector : http://groups.yahoo.com/group/themixwgroup/ DigiPol: http://groups.yahoo.com/group/Digipol (band plan policy discussion) Yahoo! Groups Links * To visit your group on the web, go to: http://groups.yahoo.com/group/digitalradio/ * Your email settings: Individual Email | Traditional * To change settings online go to: http://groups.yahoo.com/group/digitalradio/join (Yahoo! ID required) * To change settings via email: mailto:[EMAIL PROTECTED] mailto:[EMAIL PROTECTED] * To unsubscribe from this group, send an email to: [EMAIL PROTECTED] * Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
[digitalradio] Re: Concerning Signal Detection
My uncle, Charles Sumner Williams (author of Introduction to the Optical Transfer Function), who taught radio at Scott Field during WWII and retired from TI said that the problem with computer signal detection (we were discussing CW) was trying to duplicate with a computer what the human brain could do was difficult. However, once you succeeds, the computer is likely to be able to do the job better. Walt, part of what your Uncle was explaining is Heuristics ie. In computer science http://en.wikipedia.org/wiki/Computer_science, a *heuristic* is a technique designed to solve a problem that ignores whether the solution can be proven to be correct, but which usually produces a good solution or solves a simpler problem that contains or intersects with the solution of the more complex problem. -- wikipedia.org Until we can introduct a heuristic characterstic to an SDR, the results will be limited. 73... Jon W1MNK Need a Digital mode QSO? Connect to Telnet://cluster.dynalias.org Other areas of interest: The MixW Reflector : http://groups.yahoo.com/group/themixwgroup/ DigiPol: http://groups.yahoo.com/group/Digipol (band plan policy discussion) Yahoo! Groups Links * To visit your group on the web, go to: http://groups.yahoo.com/group/digitalradio/ * Your email settings: Individual Email | Traditional * To change settings online go to: http://groups.yahoo.com/group/digitalradio/join (Yahoo! ID required) * To change settings via email: mailto:[EMAIL PROTECTED] mailto:[EMAIL PROTECTED] * To unsubscribe from this group, send an email to: [EMAIL PROTECTED] * Your use of Yahoo! Groups is subject to: http://docs.yahoo.com/info/terms/
