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Quasi Synchronous??
Hi guys!
I saw this term mentioned in the specs of a radio. What does it mean exactly? That if you hope and listen long enough you can convince yourself it's synchronous? :) Lucky |
Lucky wrote: Hi guys! I saw this term mentioned in the specs of a radio. What does it mean exactly? That if you hope and listen long enough you can convince yourself it's synchronous? :) Which radio? dxAce Michigan USA |
Lucky wrote:
Hi guys! I saw this term mentioned in the specs of a radio. What does it mean exactly? That if you hope and listen long enough you can convince yourself it's synchronous? :) Lucky Which radio. The term could mean a variety of things, but if you want a specific answer, please indicate which radio and provide a link to the use of the ter,. Then, somone may be able to provide the correct (exact) answer. craigm |
Which radio...haven't heard that term.
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Quasi synchronous detection is a non-PLL type of sync detection.......like
the type that was used in the Drake R7 receiver. Basically, it consists of using a mixer to demodulate the AM signal in this way: the I.F. signal is split into two paths. The unprocessed I.F. signal (one of the paths) is applied to the RF port of a mixer, while the other path is squared up through a limiting amplifier and applied to the LO port of this same mixer. The demodulated audio is taken from the I.F. port (output port in this case) of the mixer. I did a similar design a couple of years ago, using a Philips SA637 Digital FM Receiver chip. Philips discontinued that device so I went with the AD607 for my subsequent design. I hope this helps. Pete "John S." wrote in message ups.com... Which radio...haven't heard that term. |
I believe that Kiwa detector that went on eBay recently was of this design.
"John S." wrote in message ups.com... Which radio...haven't heard that term. |
Pete KE9OA wrote: Quasi synchronous detection is a non-PLL type of sync detection.......like the type that was used in the Drake R7 receiver. Basically, it consists of using a mixer to demodulate the AM signal in this way: the I.F. signal is split into two paths. The unprocessed I.F. signal (one of the paths) is applied to the RF port of a mixer, while the other path is squared up through a limiting amplifier and applied to the LO port of this same mixer. The demodulated audio is taken from the I.F. port (output port in this case) of the mixer. I did a similar design a couple of years ago, using a Philips SA637 Digital FM Receiver chip. Philips discontinued that device so I went with the AD607 for my subsequent design. I hope this helps. Ahhhhh yes, in the Drake R7 it's known as "synchro-phase" detection. dxAce Michigan USA |
"Pete KE9OA" wrote in message ... I had one of those. It did have quite a bit of RF gain, but the I.F. strip did not have the gain that the Plessey SL6700 that is used in the HF-150 does. They are not the same receiver, performance wise. If you can find one in the 125 dollar range, it isn't a bad deal. Pete "Lucky" wrote in message ... "John S." wrote in message ups.com... Which radio...haven't heard that term. OK I'm interested in the old Lowe SRX-100 also known as the AKD Target HF3 and now the Nasa Target HF3/p or Nav-fax 200. Check on the very bottom specs under "demodulator: I'm going to buy one. They look cool and seem to have the same Lowe slower rate, faster rate knob. Simple receiver but I seem to like it from what I've read about them. Now this company makes a Nasa Target HF5E that I can only find in Germany. It's supposed to be comparable with the Lowe 150. http://www.pyacht.net/cgi-local/Soft....htm?E+scstore Lucky Hi Pete would you say it's more a portable wise type perfromance? What did you do with yours? Anything decent about it?? Lucky |
I do have the service manual for the R7 in PDF form. U1102 is the
Synchro-Phase detector chip...........it is indeed an MC1496. Good low distortion component. Pete "dxAce" wrote in message ... Pete KE9OA wrote: Exactly............it was a good sound implementation. I believe that they may have used an MC1496 for that part of the circuit. I doubt that info would be in the supplied owners manual, and I do not have a service manual otherwise I'd try and look it up. dxAce Michigan USA |
Hi Lucky,
It was ok.................. not a lot of gain in the I.F. system, but it did have enough RF gain. It is probably a matter of preference, but I like my radios to have their gain distribution set up so that the I.F. strip provides most of the system gain. This way, you get a higher amount of headroom in the front end if the gain in that section of the receiver isn't too high. It did work better than any of the portables I have used. I bumped up the gain in the I.F. strip a little bit, and I was relatively happy with it. I ended up trading it off in a combination deal for a Yaesu FRG-100, which I ended up selling along with the optional CW filter and the FM board for 300 dollars. Some older fellow in one of the Carolinas bought it. Pete Hi Pete would you say it's more a portable wise type perfromance? What did you do with yours? Anything decent about it?? Lucky |
"Pete KE9OA" wrote in message ... Hi Lucky, It was ok.................. not a lot of gain in the I.F. system, but it did have enough RF gain. It is probably a matter of preference, but I like my radios to have their gain distribution set up so that the I.F. strip provides most of the system gain. This way, you get a higher amount of headroom in the front end if the gain in that section of the receiver isn't too high. It did work better than any of the portables I have used. I bumped up the gain in the I.F. strip a little bit, and I was relatively happy with it. I ended up trading it off in a combination deal for a Yaesu FRG-100, which I ended up selling along with the optional CW filter and the FM board for 300 dollars. Some older fellow in one of the Carolinas bought it. Pete Hi Pete would you say it's more a portable wise type perfromance? What did you do with yours? Anything decent about it?? Lucky Well Pete, if you didn't end up keeping it that does say something about it. I just get a kick out of new radios especially foreign ones. Could they have improved them somewhat since you bought one? Was it the Lowe SRX-100 or the Nasa Target HF3? Lucky |
"Brian Denley" wrote in message ... Lucky wrote: Hi guys! I saw this term mentioned in the specs of a radio. What does it mean exactly? That if you hope and listen long enough you can convince yourself it's synchronous? :) Lucky I'm quasi-synchronous....sometimes! -- Brian Denley http://home.comcast.net/~b.denley/index.html I knew a guy who was Quasi-Moto :) Lucky |
jimg wrote:
in basic comm text books this is called is called 'coherent' detection. under certain conditions it can be demonstrated that the coherent demodulated snr is a 3-4 dB better than the "diode" (non-linear self-mixing) demod and a 3-5 dB worse than synchronous demodulation. under severe fading the coherent demod can actually underperform the diode demod depending upon the mixer/post-filter/etc. whereas the synchronous pll output can maintain the mixer input even if the signal disappears briefly (wrt the loop time constant and phase detector type) because of the fading performance, the ease creating high quality quadrature pll outputs, and the inherent input phase noise attenuation in the pll, it's (coherent demodulation) almost never used anymore in mixed signal designs... Hi guys! I saw this term mentioned in the specs of a radio. What does it mean exactly? That if you hope and listen long enough you can convince yourself it's synchronous? :) Lucky jimg Oregon USA |
A sync detector does not have to be a sideband-selectable type to be
a what would be referred to as a true type of sync detector. It does need to be a PLL type, though. Pete This is true, of course, but a sync. detector in modern equipment that is not sideband-selectable for the SW environment, where there's often so much adjacent channel interference, is a perversity. RK |
rkhalona wrote: A sync detector does not have to be a sideband-selectable type to be a what would be referred to as a true type of sync detector. It does need to be a PLL type, though. Pete This is true, of course, but a sync. detector in modern equipment that is not sideband-selectable for the SW environment, where there's often so much adjacent channel interference, is a perversity. You're a 'newbie'... right? My oh my, what did one ever do without 'synch'. dxAce Michigan USA |
True........most people are looking for that characteristic.
Pete "rkhalona" wrote in message oups.com... A sync detector does not have to be a sideband-selectable type to be a what would be referred to as a true type of sync detector. It does need to be a PLL type, though. Pete This is true, of course, but a sync. detector in modern equipment that is not sideband-selectable for the SW environment, where there's often so much adjacent channel interference, is a perversity. RK |
In article .com,
rkhalona wrote: A sync detector does not have to be a sideband-selectable type to be a what would be referred to as a true type of sync detector. It does need to be a PLL type, though. Pete This is true, of course, but a sync. detector in modern equipment that is not sideband-selectable for the SW environment, where there's often so much adjacent channel interference, is a perversity. Why is using an I/Q "Image reject" mixer better than just having a narrower filter? As I understand it, you're not going to get more than 50 dB rejection with an image reject mixer. Mark Zenier Washington State resident |
In article ,
Pete KE9OA wrote: "John S." wrote in message oups.com... Which radio...haven't heard that term. I believe that Kiwa detector that went on eBay recently was of this design. A guy I know who knows Craig a lot better than I do said that it used some chip designed for VCRs. (My wild ass guess would be a Philips video IF and detector chip with the synchro-phase circuit in it. TDA2540, TDA2541). Mark Zenier Washington State resident |
dxAce wrote:
You're a 'newbie'... right? LOL! If you only knew... RK |
rkhalona wrote: dxAce wrote: You're a 'newbie'... right? LOL! If you only knew... So tell me, tell us... No need to be a poseur. dxAce Michigan USA |
I've been a SWLer for at least 20 years, have a Ph.D. in EE, have 20+
years of experience in the telecomm industry (uwave, sats, cellular, UWB...) and have taught grad/undergrad comm courses at various U.S. universities. I agree with another poster that the SW8/R8B sync. detectors are among the best ever incorporated into SWL gear. My previous comment about sync. doesn't mean that one cannot achieve similar signall quality without it (e.g., using PBT, but how many portables or low-cost tabletops have PBT these days?), but the convenience of being able to select sidebands in sync mode is a big plus. RK |
rkhalona wrote: I've been a SWLer for at least 20 years, have a Ph.D. in EE, have 20+ years of experience in the telecomm industry (uwave, sats, cellular, UWB...) and have taught grad/undergrad comm courses at various U.S. universities. I agree with another poster that the SW8/R8B sync. detectors are among the best ever incorporated into SWL gear. My previous comment about sync. doesn't mean that one cannot achieve similar signall quality without it (e.g., using PBT, but how many portables or low-cost tabletops have PBT these days?), but the convenience of being able to select sidebands in sync mode is a big plus. Yep... a newbie. dxAce Michigan USA |
It's like a girl who is a Quasi Virgin, she's only allowed it in her mou$53!
"Lucky" wrote in message ... Hi guys! I saw this term mentioned in the specs of a radio. What does it mean exactly? That if you hope and listen long enough you can convince yourself it's synchronous? :) Lucky |
"rkhalona" ) writes: I've been a SWLer for at least 20 years, have a Ph.D. in EE, have 20+ years of experience in the telecomm industry (uwave, sats, cellular, UWB...) and have taught grad/undergrad comm courses at various U.S. universities. I agree with another poster that the SW8/R8B sync. detectors are among the best ever incorporated into SWL gear. My previous comment about sync. doesn't mean that one cannot achieve similar signall quality without it (e.g., using PBT, but how many portables or low-cost tabletops have PBT these days?), but the convenience of being able to select sidebands in sync mode is a big plus. RK But it seems you are mixing apples and oranges. Sync detection means a locally generated "carrier" is present, so if the signal fades the lack of a strong carrier is not a factor. It does nothing to prevent fading (which I bring up because someone recently said something along those lines here) it merely helps when the signal fades. Selectable sideband really has nothing to do with synchronous detection, other than that using the phasing method it's relatively cheap to implement compared to an expensive IF filter. It's not really like a few extra parts to a synchronous detector will add selective sideband, the added parts may be cheap but it adds complication to the circuit. When Webb wrote about the synchronous detector in CQ Magazine about it, it was the whole shebang. But, that was a time when many receivers had fairly wide IF filters, and lacked product detectors. At the same time, you'd see SSB adaptors that used the phasing method, which added that product detector and reduced the unwanted sideband. Adding synchronous circuitry to those was relatively simple, so once you added the sync circuitry you not only got DSBsc reception, but better SSB reception. What we often see is lower end receivers tossing it in (because the phasing method is a cheap way of knocking out the unwanted sideband, and plus there are ICs that do it all in one package), but it doesn't make up for the lack of a narrow IF filter with steep sides (at least not as implemented in those cheap receivers). It's a means of adding something without a major cost increase. I'm not even sure where we've veered off to. I thought the previous comment was something like synchronous detection wasn't all that important. I'd say that's true, given that people lived without it till it became a feature in relatively recent years. Someone listening to broadcast radio (am or shortwave) that are relatively strong may be the ones to benefit the most, because you can get deep fades where the sidebands are still nice and strong. Signals that you have to strain to hear, it's far less likely to be useful, because they are already below a minimum strength. You'd want to pull in other techniques at that point, and that includes the narrow IF filter that has good slopes. Michael |
In article .com,
"rkhalona" wrote: I've been a SWLer for at least 20 years, have a Ph.D. in EE, have 20+ years of experience in the telecomm industry (uwave, sats, cellular, UWB...) and have taught grad/undergrad comm courses at various U.S. universities. I agree with another poster that the SW8/R8B sync. detectors are among the best ever incorporated into SWL gear. My previous comment about sync. doesn't mean that one cannot achieve similar signall quality without it (e.g., using PBT, but how many portables or low-cost tabletops have PBT these days?), but the convenience of being able to select sidebands in sync mode is a big plus. This news group has more than it's share of Ph.D.'s and double E's it seems. Where do you think the future of telecom is going? Is it going to be mostly fiber-optic or do you think RF for the last mile to the home or business? Do you think Ethernet is winning over ATM? -- Telamon Ventura, California |
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On Fri, 03 Jun 2005 02:56:59 GMT, Telamon
wrote: In article .com, "rkhalona" wrote: I've been a SWLer for at least 20 years, have a Ph.D. in EE, have 20+ years of experience in the telecomm industry (uwave, sats, cellular, UWB...) and have taught grad/undergrad comm courses at various U.S. universities. I agree with another poster that the SW8/R8B sync. detectors are among the best ever incorporated into SWL gear. My previous comment about sync. doesn't mean that one cannot achieve similar signall quality without it (e.g., using PBT, but how many portables or low-cost tabletops have PBT these days?), but the convenience of being able to select sidebands in sync mode is a big plus. This news group has more than it's share of Ph.D.'s and double E's it seems. Where do you think the future of telecom is going? Is it going to be mostly fiber-optic or do you think RF for the last mile to the home or business? Do you think Ethernet is winning over ATM? Ermmmm...ATM (asynchronous transfer mode) is a 53-byte packet protocol that travels OVER ethernet (a method of transferring data over coax cable - and wire pairs.). See IEEE standard 802.3. Ethernet is the most widely installed local area network technology. The most commonly installed Ethernet systems are called 10BASE-T, providing transmission speeds up to 10 Mbps. Fast Ethernet LANs, 100BASE-T, provide transmission speeds up to 100 Mbps. ATM is a dedicated-connection switching technology that organizes digital data into 53-byte cell units and transmits them over a physical medium using digital signal technology. Individually, a cell is processed asynchronously relative to other related cells and is queued before being multiplexed over the transmission path. Because ATM is designed to be easily implemented by hardware (rather than software), faster processing and switching speeds are possible. The prespecified bit rates are either 155.520 Mbps or 622.080 Mbps. Speeds on ATM networks can reach 10 Gbps. Regards, Al in CNMI ----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 120,000+ Newsgroups ----= East and West-Coast Server Farms - Total Privacy via Encryption =---- |
In article ,
Tebojockey wrote: On Fri, 03 Jun 2005 02:56:59 GMT, Telamon wrote: In article .com, "rkhalona" wrote: I've been a SWLer for at least 20 years, have a Ph.D. in EE, have 20+ years of experience in the telecomm industry (uwave, sats, cellular, UWB...) and have taught grad/undergrad comm courses at various U.S. universities. I agree with another poster that the SW8/R8B sync. detectors are among the best ever incorporated into SWL gear. My previous comment about sync. doesn't mean that one cannot achieve similar signall quality without it (e.g., using PBT, but how many portables or low-cost tabletops have PBT these days?), but the convenience of being able to select sidebands in sync mode is a big plus. This news group has more than it's share of Ph.D.'s and double E's it seems. Where do you think the future of telecom is going? Is it going to be mostly fiber-optic or do you think RF for the last mile to the home or business? Do you think Ethernet is winning over ATM? Ermmmm...ATM (asynchronous transfer mode) is a 53-byte packet protocol that travels OVER ethernet (a method of transferring data over coax cable - and wire pairs.). See IEEE standard 802.3. Ethernet is the most widely installed local area network technology. The most commonly installed Ethernet systems are called 10BASE-T, providing transmission speeds up to 10 Mbps. Fast Ethernet LANs, 100BASE-T, provide transmission speeds up to 100 Mbps. I suppose ATM could be stuffed into a ethernet frame but I have not heard of it. In the telecom world it's ATM over SONET that terminates at my DSL modem. The DSL modem is used as a bridge. Between my DSL modem to the computer it's ethernet so I can use the usual routers and or hubs. ATM is a dedicated-connection switching technology that organizes digital data into 53-byte cell units and transmits them over a physical medium using digital signal technology. Individually, a cell is processed asynchronously relative to other related cells and is queued before being multiplexed over the transmission path. Because ATM is designed to be easily implemented by hardware (rather than software), faster processing and switching speeds are possible. The prespecified bit rates are either 155.520 Mbps or 622.080 Mbps. Speeds on ATM networks can reach 10 Gbps. It can go over any of the SONET rates. Maybe I should have been more specific. The question is whether ethernet will take over the local metro area from ATM over SONET. I expect that ATM over SONET will be maintained at higher levels in the network. -- Telamon Ventura, California |
"Pete KE9OA" wrote in message ... I had one of those. It did have quite a bit of RF gain, but the I.F. strip did not have the gain that the Plessey SL6700 that is used in the HF-150 does. They are not the same receiver, performance wise. If you can find one in the 125 dollar range, it isn't a bad deal. Pete "Lucky" wrote in message ... "John S." wrote in message ups.com... Which radio...haven't heard that term. OK I'm interested in the old Lowe SRX-100 also known as the AKD Target HF3 and now the Nasa Target HF3/p or Nav-fax 200. Check on the very bottom specs under "demodulator: I'm going to buy one. They look cool and seem to have the same Lowe slower rate, faster rate knob. Simple receiver but I seem to like it from what I've read about them. Now this company makes a Nasa Target HF5E that I can only find in Germany. It's supposed to be comparable with the Lowe 150. http://www.pyacht.net/cgi-local/Soft....htm?E+scstore Lucky Pete, I ordered one yesterday and found a dealer in this country who has them. Wasn't easy for sure but I did it. They are much cheaper here then in the UK for sure. Like 1/2 the price. I should be getting it hopefully today or tomorrow! I asked around and one supplier tracked the radio down for me. It's renamed again in the U.S. Can't wait to fool around with it. Have a good day. Lucky |
Lucky wrote: "Pete KE9OA" wrote in message ... I had one of those. It did have quite a bit of RF gain, but the I.F. strip did not have the gain that the Plessey SL6700 that is used in the HF-150 does. They are not the same receiver, performance wise. If you can find one in the 125 dollar range, it isn't a bad deal. Pete "Lucky" wrote in message ... "John S." wrote in message ups.com... Which radio...haven't heard that term. OK I'm interested in the old Lowe SRX-100 also known as the AKD Target HF3 and now the Nasa Target HF3/p or Nav-fax 200. Check on the very bottom specs under "demodulator: I'm going to buy one. They look cool and seem to have the same Lowe slower rate, faster rate knob. Simple receiver but I seem to like it from what I've read about them. Now this company makes a Nasa Target HF5E that I can only find in Germany. It's supposed to be comparable with the Lowe 150. http://www.pyacht.net/cgi-local/Soft....htm?E+scstore Lucky Pete, I ordered one yesterday and found a dealer in this country who has them. Wasn't easy for sure but I did it. They are much cheaper here then in the UK for sure. Like 1/2 the price. I should be getting it hopefully today or tomorrow! I asked around and one supplier tracked the radio down for me. It's renamed again in the U.S. Can't wait to fool around with it. I sure hope it has no dents or scratches. Also hope they don't mistakenly ship it to Japan. dxAce Michigan USA |
But it seems you are mixing apples and oranges.
Not really, because the ability to select sidebands while in sync mode is a big plus in mitigating against ACI. Of course, one can do the same with just SSB, but going through the trouble of having a sync detector and not being able to select sidebands seems perverse nowadays. Sync detection means a locally generated "carrier" is present, so if the signal fades the lack of a strong carrier is not a factor. It does nothing to prevent fading (which I bring up because someone recently said something along those lines here) it merely helps when the signal fades. There is so much loose talk about this, but I think the above is a good way of putting it. First of all, how could one *prevent* fading if the channel is fixed? Sync does not prevent fading, but as long as the detector is able to reasonably track the carrier phase in the fading medium, it will provide better performance than an envelope (amplitude) detector, so in this sense sync detection does mitigate against fading. Selectable sideband really has nothing to do with synchronous detection, other than that using the phasing method it's relatively cheap to implement compared to an expensive IF filter. True, this is why I think it's perverse when most of the expense is already in designing a PLL-type sync not to go the extra step in being able to select sidebands. It's a question of implementation. I'm not even sure where we've veered off to. I thought the previous comment was something like synchronous detection wasn't all that important. I'd say that's true, given that people lived without it till it became a feature in relatively recent years. Someone listening to broadcast radio (am or shortwave) that are relatively strong may be the ones to benefit the most, because you can get deep fades where the sidebands are still nice and strong. Signals that you have to strain to hear, it's far less likely to be useful, because they are already below a minimum strength. You'd want to pull in other techniques at that point, and that includes the narrow IF filter that has good slopes. The opposite is true. When you have very high SNR conditions, an envelope detector performs almost as well as a sync detector, but it is in the low-to-medium SNR region where you will see the performance improvement, especially in terms of signal intelligibility. This can be verified by anyone with a sync detector radio. Try listening to a strong signal in the AM band with and without sync: there is almost no perceived change in signal quality. Try the same on shortwave, you'll see more of an improvement in sync mode. RK |
Mark Zenier ) writes: In article , Pete KE9OA wrote: "John S." wrote in message roups.com... Which radio...haven't heard that term. I believe that Kiwa detector that went on eBay recently was of this design. A guy I know who knows Craig a lot better than I do said that it used some chip designed for VCRs. (My wild ass guess would be a Philips video IF and detector chip with the synchro-phase circuit in it. TDA2540, TDA2541). Mark Zenier Washington State resident Are we talking what's no called "quasi-synchronous"? Decades ago, Motorola had the MC1330 which was a mixer and a limiter in one package, and intended as a quasi-synchronous detector in tv sets. I suspect if driven properly, the MC1350 IF amplifier would do it, since the stage that is voltage controlled is just a "Gilbert Cell Mixer". When the MC1496 Mixer (a "Gilbert Cell" long before the term was applied) came out in the early seventies, there was an article in Ham Radio magazine about it, I think by Roy Hejhall, and one of the examples was as a "quasi-synchronous" detector, though I'm not sure if it explained it as such or just as a fancy AM detector. Didn't even need a limiter, if you fed a strong enough signal into it. The datasheet or application note for the MC1496 includes the circuit. Of course, there have also been examples of them based on FM detectors. Many of those in ICs used a scheme that included a balanced mixer, and of course it had the limiter, so all you had to do was hook it up. Michael |
It should be a fun radio. I did like mine. Let the folks on the Yahoo group
know about it..........I think Dave Z. would be interested. Pete "Lucky" wrote in message ... "Pete KE9OA" wrote in message ... I had one of those. It did have quite a bit of RF gain, but the I.F. strip did not have the gain that the Plessey SL6700 that is used in the HF-150 does. They are not the same receiver, performance wise. If you can find one in the 125 dollar range, it isn't a bad deal. Pete "Lucky" wrote in message ... "John S." wrote in message ups.com... Which radio...haven't heard that term. OK I'm interested in the old Lowe SRX-100 also known as the AKD Target HF3 and now the Nasa Target HF3/p or Nav-fax 200. Check on the very bottom specs under "demodulator: I'm going to buy one. They look cool and seem to have the same Lowe slower rate, faster rate knob. Simple receiver but I seem to like it from what I've read about them. Now this company makes a Nasa Target HF5E that I can only find in Germany. It's supposed to be comparable with the Lowe 150. http://www.pyacht.net/cgi-local/Soft....htm?E+scstore Lucky Pete, I ordered one yesterday and found a dealer in this country who has them. Wasn't easy for sure but I did it. They are much cheaper here then in the UK for sure. Like 1/2 the price. I should be getting it hopefully today or tomorrow! I asked around and one supplier tracked the radio down for me. It's renamed again in the U.S. Can't wait to fool around with it. Have a good day. Lucky |
On Fri, 03 Jun 2005 04:27:06 GMT, Telamon
wrote: In article , Tebojockey wrote: On Fri, 03 Jun 2005 02:56:59 GMT, Telamon wrote: In article .com, "rkhalona" wrote: I've been a SWLer for at least 20 years, have a Ph.D. in EE, have 20+ years of experience in the telecomm industry (uwave, sats, cellular, UWB...) and have taught grad/undergrad comm courses at various U.S. universities. I agree with another poster that the SW8/R8B sync. detectors are among the best ever incorporated into SWL gear. My previous comment about sync. doesn't mean that one cannot achieve similar signall quality without it (e.g., using PBT, but how many portables or low-cost tabletops have PBT these days?), but the convenience of being able to select sidebands in sync mode is a big plus. This news group has more than it's share of Ph.D.'s and double E's it seems. Where do you think the future of telecom is going? Is it going to be mostly fiber-optic or do you think RF for the last mile to the home or business? Do you think Ethernet is winning over ATM? Ermmmm...ATM (asynchronous transfer mode) is a 53-byte packet protocol that travels OVER ethernet (a method of transferring data over coax cable - and wire pairs.). See IEEE standard 802.3. Ethernet is the most widely installed local area network technology. The most commonly installed Ethernet systems are called 10BASE-T, providing transmission speeds up to 10 Mbps. Fast Ethernet LANs, 100BASE-T, provide transmission speeds up to 100 Mbps. I suppose ATM could be stuffed into a ethernet frame but I have not heard of it. In the telecom world it's ATM over SONET that terminates at my DSL modem. The DSL modem is used as a bridge. Between my DSL modem to the computer it's ethernet so I can use the usual routers and or hubs. ATM is a dedicated-connection switching technology that organizes digital data into 53-byte cell units and transmits them over a physical medium using digital signal technology. Individually, a cell is processed asynchronously relative to other related cells and is queued before being multiplexed over the transmission path. Because ATM is designed to be easily implemented by hardware (rather than software), faster processing and switching speeds are possible. The prespecified bit rates are either 155.520 Mbps or 622.080 Mbps. Speeds on ATM networks can reach 10 Gbps. It can go over any of the SONET rates. Maybe I should have been more specific. The question is whether ethernet will take over the local metro area from ATM over SONET. I expect that ATM over SONET will be maintained at higher levels in the network. R, but good discussion tho! Regards, Al in CNMI ----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==---- http://www.newsfeeds.com The #1 Newsgroup Service in the World! 120,000+ Newsgroups ----= East and West-Coast Server Farms - Total Privacy via Encryption =---- |
In article ,
Tebojockey wrote: On Fri, 03 Jun 2005 04:27:06 GMT, Telamon wrote: In article , Tebojockey wrote: On Fri, 03 Jun 2005 02:56:59 GMT, Telamon wrote: In article .com, "rkhalona" wrote: I've been a SWLer for at least 20 years, have a Ph.D. in EE, have 20+ years of experience in the telecomm industry (uwave, sats, cellular, UWB...) and have taught grad/undergrad comm courses at various U.S. universities. I agree with another poster that the SW8/R8B sync. detectors are among the best ever incorporated into SWL gear. My previous comment about sync. doesn't mean that one cannot achieve similar signall quality without it (e.g., using PBT, but how many portables or low-cost tabletops have PBT these days?), but the convenience of being able to select sidebands in sync mode is a big plus. This news group has more than it's share of Ph.D.'s and double E's it seems. Where do you think the future of telecom is going? Is it going to be mostly fiber-optic or do you think RF for the last mile to the home or business? Do you think Ethernet is winning over ATM? Ermmmm...ATM (asynchronous transfer mode) is a 53-byte packet protocol that travels OVER ethernet (a method of transferring data over coax cable - and wire pairs.). See IEEE standard 802.3. Ethernet is the most widely installed local area network technology. The most commonly installed Ethernet systems are called 10BASE-T, providing transmission speeds up to 10 Mbps. Fast Ethernet LANs, 100BASE-T, provide transmission speeds up to 100 Mbps. I suppose ATM could be stuffed into a ethernet frame but I have not heard of it. In the telecom world it's ATM over SONET that terminates at my DSL modem. The DSL modem is used as a bridge. Between my DSL modem to the computer it's ethernet so I can use the usual routers and or hubs. ATM is a dedicated-connection switching technology that organizes digital data into 53-byte cell units and transmits them over a physical medium using digital signal technology. Individually, a cell is processed asynchronously relative to other related cells and is queued before being multiplexed over the transmission path. Because ATM is designed to be easily implemented by hardware (rather than software), faster processing and switching speeds are possible. The prespecified bit rates are either 155.520 Mbps or 622.080 Mbps. Speeds on ATM networks can reach 10 Gbps. It can go over any of the SONET rates. Maybe I should have been more specific. The question is whether ethernet will take over the local metro area from ATM over SONET. I expect that ATM over SONET will be maintained at higher levels in the network. R, but good discussion tho! To bad the Ph.D. never came back to answer my question. -- Telamon Ventura, California |
Telamon asked:
Where do you think the future of telecom is going? Is it going to be mostly fiber-optic or do you think RF for the last mile to the home or business? Do you think Ethernet is winning over ATM? Anyone who claims to know the answer to your first question will either become a millionaire quickly or will be surprised by the changes. There's a war going on over the last mile, as you know. Right now cable/DSL are predominant, at least in the U.S., but wireless technologies will eventually push through and will be strong competitors in this market. Regarding the last question, there is a strong push for VoIP (voice over Internet Protocol). Most of wireless traffic is still voice and All-IP system architectures (as opposed to dual circuit switched/packet switched) are the way of the future, but there are important Quality of Service (QoS) issues to be solved regarding voice over IP (esp. end-to-end delay). We should know more definitively in the near future. RK |
In article .com,
"rkhalona" wrote: Telamon asked: Where do you think the future of telecom is going? Is it going to be mostly fiber-optic or do you think RF for the last mile to the home or business? Do you think Ethernet is winning over ATM? Anyone who claims to know the answer to your first question will either become a millionaire quickly or will be surprised by the changes. There's a war going on over the last mile, as you know. Right now cable/DSL are predominant, at least in the U.S., but wireless technologies will eventually push through and will be strong competitors in this market. Regarding the last question, there is a strong push for VoIP (voice over Internet Protocol). Most of wireless traffic is still voice and All-IP system architectures (as opposed to dual circuit switched/packet switched) are the way of the future, but there are important Quality of Service (QoS) issues to be solved regarding voice over IP (esp. end-to-end delay). We should know more definitively in the near future. Good answer. I used to think it was just a battle between ATM and ethernet over wire, then fiber to the home started looking more promising and now an RF link could end up dominating. I think BPL broadband over power lines is a real loser but some people are pursuing that for the "last Mile" or metro area coverage. Here is a page to keep track of that: http://www.plexeon.com/ Yeah, quality of service is likely going to go down in the process. That going to happen if voice traffic uses computer technology like ethernet instead of the telecom framing technology with all its redundancy, error correction and intelligent switching not to mention dedicated circuits or at least time slots in the frames until a call is ended. Makes me wonder how those voice over IP companies like Lingo or Vonage are doing these days? -- Telamon Ventura, California |
In article
, Telamon wrote: In article .com, "rkhalona" wrote: Telamon asked: Where do you think the future of telecom is going? Is it going to be mostly fiber-optic or do you think RF for the last mile to the home or business? Do you think Ethernet is winning over ATM? Anyone who claims to know the answer to your first question will either become a millionaire quickly or will be surprised by the changes. There's a war going on over the last mile, as you know. Right now cable/DSL are predominant, at least in the U.S., but wireless technologies will eventually push through and will be strong competitors in this market. Regarding the last question, there is a strong push for VoIP (voice over Internet Protocol). Most of wireless traffic is still voice and All-IP system architectures (as opposed to dual circuit switched/packet switched) are the way of the future, but there are important Quality of Service (QoS) issues to be solved regarding voice over IP (esp. end-to-end delay). We should know more definitively in the near future. Good answer. I used to think it was just a battle between ATM and ethernet over wire, then fiber to the home started looking more promising and now an RF link could end up dominating. I think BPL broadband over power lines is a real loser but some people are pursuing that for the "last Mile" or metro area coverage. Here is a page to keep track of that: http://www.plexeon.com/ Yeah, quality of service is likely going to go down in the process. That going to happen if voice traffic uses computer technology like ethernet instead of the telecom framing technology with all its redundancy, error correction and intelligent switching not to mention dedicated circuits or at least time slots in the frames until a call is ended. Makes me wonder how those voice over IP companies like Lingo or Vonage are doing these days? Looks like Ethernet over SONET is becoming more popular theses days. -- Telamon Ventura, California |
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