K3 & ADAT ADT-200A by HB9CBU
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Re: K3 & ADAT ADT-200A by HB9CBU
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Some folk suffer extremely strong QRM from broadcasters on 40m (particularly
on the east coast of Scotland) and to them there is a real desire for the best possible gear to hear weak stations amongst huge bc signals from Europe. That's where receivers like the Perseus and others come in to their own. David G3UNA ----- Original Message ----- From: "Ron D'Eau Claire" <[hidden email]> To: <[hidden email]> Sent: Tuesday, December 02, 2008 10:14 PM Subject: RE: [Elecraft] K3 & ADAT ADT-200A by HB9CBU > John KD8K wrote: > > . This discussion does raise a few questions in my mind that I > would like to ask. To me it is a question of the theoretical as opposed > to the practical. Does it really matter if a receiver can hold up to a > 80db over 9 signal 2 KHz away or is this just a theoretical exercise? > Would not the transmitted Phase Noise, IMD, and perhaps key clicks be > the limiting factor or am I wrong about this? > > Is there is a point of no return where increased close in dynamic range > no long matters because modern transmitters simply can not or do not > transmit a signal that clean. If so, then has the K3 and the Perseus > reached that point of no return and the question of which one has a > better close in dynamic range is more of a theoretical then a practical > exercise. > > --------------------------------------------------- > > Good points to consider, *especially* realizing that the transmitter > you're > hearing might have been built anywhere from 1930 onward. There's lots of > old > gear in use out there, and there are a lot of homebrewers learning > "hands-on" engineering building their own stuff with little or no > equipment > to do this sort of critical analysis. It's all perfectly legal and proper > to > use on the Ham bands - even encouraged. > > I doubt if many 1950 Viking I, Elmac, B&W, Hallicrafters or similar > vintage > transmitters are found in contests these days. So the concern expressed is > really by the hard-core highly-competitive contesters working in extreme > conditions most of us will never experience. For others it's the fun of > the > chase toward ever and ever "better" performance as an end in itself, > whether > or not it has any practical application on the air. Those, too, are > perfectly legal and proper pursuits - even encouraged. > > For the rest of Hamdom, these specifications are rather unimportant. > > Ron AC7AC > > > > _______________________________________________ > Elecraft mailing list > Post to: [hidden email] > You must be a subscriber to post to the list. > Subscriber Info (Addr. Change, sub, unsub etc.): > http://mailman.qth.net/mailman/listinfo/elecraft > > Help: http://mailman.qth.net/subscribers.htm > Elecraft web page: http://www.elecraft.com _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
Re: K3 & ADAT ADT-200A by HB9CBU
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David Cutter wrote: > Some folk suffer extremely strong QRM from broadcasters on 40m > (particularly on the east coast of Scotland) and to them there is a > real desire for the best possible gear to hear weak stations amongst > huge bc signals from Europe. That's where receivers like the Perseus > and others come in to their own. > > Hi David, Yes I can see your point, and I am certainly not questioning the benefit of High Dynamic range receivers in those situations. I guess what I am having a hard time understanding how it would be possible for any receiver, regardless of the dynamic range of the receiver, to receive a weak signal 2 Khz away from, say a 80db over 9 broadcast or other signal. Would not the IMD, sidebands, and splatter from the broadcast station itself be so severe as to prevent this? Or am I overstating the effects of transmitted phase noise and IMD? As I mentioned in my previous post, there is no way I could see operating 2 Khz away from the very strong signal of my ham neighbor. His transmitted IMD would be way too severe. But I can easily operate 20 Khz or more away with the K3. To me, any minor difference in close in dynamic range between say the Perseus and the K3 is of little or no importance in this situation. I could not receive a weak signal so close to such a strong signal anyhow because of his transmitted IMD. But the wider spaced number's matter a great deal, and that is what concerns me when I see a 117-123db BDR as compared to 140db at wider spacings. 73, John, KD8K _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
Re: K3 & ADAT ADT-200A by HB9CBU
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I have to agree with the reasoning behind John's comments here. As
has been opined by many, the K3 really shines its brightest on CW, where spurious transmitter products are typically limited to the occasional key clicks. The percentage of misadjusted and badly offending transmitters is MUCH greater on SSB; I don't think anybody would argue with that. That said, it's all a matter of arithmetic, and there are a lot of variables involved -- on both the TX and the RX ends. But all other factors being equal, how much is it worth to have the needed receiver dynamic range for that one must-have SSB contest or DX QSO that you wouldn't get without it? Many would say (no trademark infringement intended), "Priceless!" For most of us, that isn't literally true, of course. You do reach a point of diminishing returns with anything, especially in engineering. The K3, IMO, strikes what is just about a perfect balance between high-end performance and price. No other radio even comes close to the K3's price/performance ratio, as far as I can tell. Bill W5WVO ----- Original Message ----- From: "John A. McCabe" <[hidden email]> To: "elecraft" <[hidden email]> Sent: Tuesday, December 02, 2008 6:11 PM Subject: Re: [Elecraft] K3 & ADAT ADT-200A by HB9CBU > > > David Cutter wrote: > > Some folk suffer extremely strong QRM from broadcasters on 40m > > (particularly on the east coast of Scotland) and to them there is a > > real desire for the best possible gear to hear weak stations amongst > > huge bc signals from Europe. That's where receivers like the Perseus > > and others come in to their own. > > > > > > Hi David, > > Yes I can see your point, and I am certainly not questioning the benefit > of High Dynamic range receivers in those situations. I guess what I am > having a hard time understanding how it would be possible for any > receiver, regardless of the dynamic range of the receiver, to receive a > weak signal 2 Khz away from, say a 80db over 9 broadcast or other > signal. Would not the IMD, sidebands, and splatter from the broadcast > station itself be so severe as to prevent this? Or am I overstating the > effects of transmitted phase noise and IMD? As I mentioned in my > previous post, there is no way I could see operating 2 Khz away from the > very strong signal of my ham neighbor. His transmitted IMD would be way > too severe. But I can easily operate 20 Khz or more away with the K3. > To me, any minor difference in close in dynamic range between say the > Perseus and the K3 is of little or no importance in this situation. I > could not receive a weak signal so close to such a strong signal anyhow > because of his transmitted IMD. But the wider spaced number's matter a > great deal, and that is what concerns me when I see a 117-123db BDR as > compared to 140db at wider spacings. > > 73, > > John, KD8K > > _______________________________________________ > Elecraft mailing list > Post to: [hidden email] > You must be a subscriber to post to the list. > Subscriber Info (Addr. Change, sub, unsub etc.): > http://mailman.qth.net/mailman/listinfo/elecraft > > Help: http://mailman.qth.net/subscribers.htm > Elecraft web page: http://www.elecraft.com > _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
RE: K3 & ADAT ADT-200A by HB9CBU
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In reply to this post by Philip Covington
> You are making the incorrect assumption that we have no > control over the upper or lower limits. If band or sky noise > is the limiting factor on the low end, then adding > attenuation in front of the ADC to adjust for this has the > benefit of increasing the high end limit also. This ideally > has not changed the dynamic range, but only shifted the upper > and lower limits. No, if band noise at -110 dBm is the limiting factor as it often is below 5 MHz, no amount of attenuation is going to allow you to resolve a - 125 dBm signal. Attenuation may help you handle blocking signals, particularly those 20 to 100 KHz away that are eliminated by the narrow filtering in other receiver designs and thus deal with the "window overload" issues but that's all that moving the "IMD range" can accomplish. > The Perseus or QS1R will easily outperform the K3 in the case > of multiple strong signals in discerning a weak signal as you > have described. This is WITHOUT AGC in front of the ADC. I do not believe that any wideband SDR can cope with the instantaneous peaks greater than the ADC rail in the limiting condition (a large number of extremely strong, say greater than -10 dBm, within the bandpass filter "window."). While the chance of the instantaneous maximum decreases as the number of signals increases, the average signal level continues to increase at an exponential rate. 73, ... Joe, W4TV > -----Original Message----- > From: [hidden email] > [mailto:[hidden email]] On Behalf Of Philip > Covington > Sent: Tuesday, December 02, 2008 6:12 AM > To: [hidden email] > Cc: [hidden email]; Bill W4ZV > Subject: Re: [Elecraft] K3 & ADAT ADT-200A by HB9CBU > > > On Mon, Dec 1, 2008 at 8:38 PM, Joe Subich, W4TV > <[hidden email]> wrote: > > > Of course, but there is still a finite range between the > > two limits. The maximum instantaneous peak is driven by > > the number and strength of incoming signals and the minimum > > discernable signal level is defined not by processing gain > but by "sky > > noise." All the processing gain goes only so far ... the limit is > > still well above the theoretical ability to detect one > signal in the > > absence of noise. Processing gain may be of value at microwave > > frequencies with a quiet sky but it is not going to help > below 10 MHz > > with extreme signals and high noise levels. > > > > 73, > > > > ... Joe, W4TV > > You are making the incorrect assumption that we have no > control over the upper or lower limits. If band or sky noise > is the limiting factor on the low end, then adding > attenuation in front of the ADC to adjust for this has the > benefit of increasing the high end limit also. This ideally > has not changed the dynamic range, but only shifted the upper > and lower limits. > > The Perseus or QS1R will easily outperform the K3 in the case > of multiple strong signals in discerning a weak signal as you > have described. This is WITHOUT AGC in front of the ADC. > > -- > Phil Covington > Software Radio Laboratory LLC > Columbus, Ohio > http://www.srl-llc.com _______________________________________________ > Elecraft mailing list > Post to: [hidden email] > You must be a subscriber to post to the list. > Subscriber Info (Addr. Change, sub, unsub etc.): > http://mailman.qth.net/mailman/listinfo/elecraft > > Help: http://mailman.qth.net/subscribers.htm > Elecraft web page: http://www.elecraft.com _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
Re: K3 & ADAT ADT-200A by HB9CBU
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In reply to this post by John A. McCabe
John
Can't help you with numbers, just the experience of friends in that situation, ie they can operate with special receivers having special mixers, often home brew, whereas it is impossible without. David G3UNA > > > David Cutter wrote: >> Some folk suffer extremely strong QRM from broadcasters on 40m >> (particularly on the east coast of Scotland) and to them there is a real >> desire for the best possible gear to hear weak stations amongst huge bc >> signals from Europe. That's where receivers like the Perseus and others >> come in to their own. >> >> > > Hi David, > > Yes I can see your point, and I am certainly not questioning the benefit > of High Dynamic range receivers in those situations. I guess what I am > having a hard time understanding how it would be possible for any > receiver, regardless of the dynamic range of the receiver, to receive a > weak signal 2 Khz away from, say a 80db over 9 broadcast or other signal. > Would not the IMD, sidebands, and splatter from the broadcast station > itself be so severe as to prevent this? Or am I overstating the effects of > transmitted phase noise and IMD? As I mentioned in my previous post, there > is no way I could see operating 2 Khz away from the very strong signal of > my ham neighbor. His transmitted IMD would be way too severe. But I can > easily operate 20 Khz or more away with the K3. To me, any minor > difference in close in dynamic range between say the Perseus and the K3 is > of little or no importance in this situation. I could not receive a weak > signal so close to such a strong signal anyhow because of his transmitted > IMD. But the wider spaced number's matter a great deal, and that is what > concerns me when I see a 117-123db BDR as compared to 140db at wider > spacings. > > 73, > > John, KD8K > Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
Re: K3 & ADAT ADT-200A by HB9CBU
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In reply to this post by Joe Subich, W4TV-3
On Wed, Dec 3, 2008 at 12:55 AM, Joe Subich, W4TV
<[hidden email]> wrote: >.> You are making the incorrect assumption that we have no >> control over the upper or lower limits. If band or sky noise >> is the limiting factor on the low end, then adding >> attenuation in front of the ADC to adjust for this has the >> benefit of increasing the high end limit also. This ideally >> has not changed the dynamic range, but only shifted the upper >> and lower limits. > No, if band noise at -110 dBm is the limiting factor as it > often is below 5 MHz, no amount of attenuation is going to > allow you to resolve a - 125 dBm signal. Attenuation may > help you handle blocking signals, particularly those 20 to > 100 KHz away that are eliminated by the narrow filtering > in other receiver designs and thus deal with the "window > overload" issues but that's all that moving the "IMD range" > can accomplish. Where in my statement above did I say that attenuation is going to help you receive a -125 dBm signal when the band noise is at -110 dBm? You won't be able to do that with a K3 or a SDR. I don't know where you got this idea. I was responding to your claim that we had no control over the lower input limit to the ADC and somehow that would limit BDR. We do have control over the lower input limit via attenuation (or gain). >> The Perseus or QS1R will easily outperform the K3 in the case >> of multiple strong signals in discerning a weak signal as you >> have described. This is WITHOUT AGC in front of the ADC. > > I do not believe that any wideband SDR can cope with the > instantaneous peaks greater than the ADC rail in the > limiting condition (a large number of extremely strong, > say greater than -10 dBm, within the bandpass filter > "window."). While the chance of the instantaneous maximum > decreases as the number of signals increases, the average > signal level continues to increase at an exponential rate. > > 73, > > ... Joe, W4TV I can tell you that QS1R can handle multiple 0 dBm signals in or outside of the bandpass filter "window", whether you believe it or not is up to you. If you exceed the clipping limit ( +9 dBm with no attenuation in QS1R) then that's it - but that is true for the K3's ADC also. -- Phil Covington Software Radio Laboratory LLC Columbus, Ohio http://www.srl-llc.com _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
Re: K3 & ADAT ADT-200A by HB9CBU
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In reply to this post by John A. McCabe
Hi John,
In this part of Scotland (approx 56N 3W), the carrier levels of many of the BC stations at 7100 kHz and above get up to +5dbm / +10dbm if propagation is "normal". These are measured levels at the shack end of a coax feeder with my backup 40m dipole at 70ft selected and in use. It is possible to work SSB DX among these BC stations, most of which are spaced by 5 kHz, but it does require a receiver whose close in *and* far out performance is good in terms of Spurious Free Dynamic Range etc. BC TX phase noise has not appeared to be a problem, but I hope to receive a plot of a particular BC TX's phase noise to help me fully understand why BC TX phase noise has not been a problem here. On the other hand legitimate modulation sidebands produced by these BC stations can be a problem in terms of raw QRM, but there might be a way to deal with this type of QRM. I do not have any neighbours who are hams, so I cannot comment on phase noise problems from nearby ham TXs. Methods to solve the key click problem at the receiving end are being investigated. I have a Perseus which appears to perform well in this signal environment, but since this is a subjective observation I need to run suitable multitone IMD tests to simulate the effect of BC stations and obtain real data. Perseus performs very well indeed when used as an auxiliary IF behind a H-Mode mixer and quadrature 2.5 kHz roofing filter front end that has small negative gain for reasons of large spurious free dynamic range at all spacings. A post mixer amplifier is not required in this front end whose noise figure is 10db when followed by a low noise IF. Perseus performs very well when used as a panadapter after the H-Mode mixer with the transfer gain set to 0db, but again these comments about Perseus are based on use not measurement. As I do not have a K3 I cannot make any comparisons between the K3 and Perseus based on use. 73, Geoff GM4ESD John A. McCabe wrote on Wednesday, December 03, 2008 at 1:11 AM > Hi David, > > Yes I can see your point, and I am certainly not questioning the benefit > of High Dynamic range receivers in those situations. I guess what I am > having a hard time understanding how it would be possible for any > receiver, regardless of the dynamic range of the receiver, to receive a > weak signal 2 Khz away from, say a 80db over 9 broadcast or other signal. > Would not the IMD, sidebands, and splatter from the broadcast station > itself be so severe as to prevent this? Or am I overstating the effects of > transmitted phase noise and IMD? As I mentioned in my previous post, there > is no way I could see operating 2 Khz away from the very strong signal of > my ham neighbor. His transmitted IMD would be way too severe. But I can > easily operate 20 Khz or more away with the K3. To me, any minor > difference in close in dynamic range between say the Perseus and the K3 is > of little or no importance in this situation. I could not receive a weak > signal so close to such a strong signal anyhow because of his transmitted > IMD. But the wider spaced number's matter a great deal, and that is what > concerns me when I see a 117-123db BDR as compared to 140db at wider > spacings. _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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This is a fascinating, informative discussion. "Thank you" to the
principals for keeping it by-and-large on a super-high plane. Unfortunately I am not versed in the technologies being explored, and would really appreciate - after the issues are fully discussed, don't need a blow-by-blow - a summary that I as a digital-savvy ham can understand and appreciate. In fields where I do consider myself expert, I have always found that if I can not explain what I know in appropriately over-simplified lay terms, I really didn't know what I was talking about. A challenge goes out to the experts here. Monty K2DLJ _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
Re: K3 & ADAT ADT-200A by HB9CBU
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In reply to this post by Geoffrey Mackenzie-Kennedy
I have been following this discussion with casual interest, and I
observe that we have come "full circle" once again with receiver front ends. In the beginning we had 'receivers' that could hear much of the RF specturm - a detector connected to an antenna, later selectivity was used ahead of the detector to restrict the signals reaching the detector and we had TRF designs with lots of tuning knobs Then we had superhetrodyne receivers that were known to do better if one placed some selectivity prior to the front end, but the selectivity was achieved at some intermediate frequency. Then there were mixers and stable oscillators developed which could work well into the VHF region, so receivers were designed with wide open front ends and a 1st IF in the low VHF spectrum and was then downconverted to achieve selectivity - while some of these were very good receivers, they suffered from front end overload and other deficiencies. Then the K2 came along substantiating that a single conversion receiver could be a top performer with bandpass selectivity placed prior to the mixer to reduce the amount of undesired signals in the receiver front end and the ultimate selectivity placed as close to the front end as possible. The K3 followed by still using front end bandpass filtering and a roofing filter at the 1st IF followed by an ADC to get into the digital processing arena. Now we have ADCs available that will work into the upper HF and lower VHF at a reasonable price and we are once again creating receivers with wide open front ends. Yes, they are SDR receivers with the loads of features that digital processing can provide - and it will get better as more processing power is packed into smaller and smaller spaces. We seem to be fascinated with the panoramic display of the spectrum and the ease of picking out signals visually and simply clicking on them to tune - the current technology makes that easy. I wonder what is next - It seems to me that we reach a practical limit for front end sensitivity when a receiver can hear below the band noise - and then BDR, IMD and other parameters become important. It will be interesting to see what the next major generation of receiver concepts provides. Ain't technology wonderful? 73, Don W3FPR _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
Re: K3 & ADAT ADT-200A by HB9CBU
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In reply to this post by Philip Covington
On Wed, Dec 3, 2008 at 6:22 AM, Philip Covington <[hidden email]> wrote:
> On Wed, Dec 3, 2008 at 12:55 AM, Joe Subich, W4TV >> I do not believe that any wideband SDR can cope with the >> instantaneous peaks greater than the ADC rail in the >> limiting condition (a large number of extremely strong, >> say greater than -10 dBm, within the bandpass filter >> "window."). While the chance of the instantaneous maximum >> decreases as the number of signals increases, the average >> signal level continues to increase at an exponential rate. >> >> 73, >> >> ... Joe, W4TV > > I can tell you that QS1R can handle multiple 0 dBm signals in or > outside of the bandpass filter "window", whether you believe it or not > is up to you. If you exceed the clipping limit ( +9 dBm with no > attenuation in QS1R) then that's it - but that is true for the K3's > ADC also. > > -- > Phil Covington > Software Radio Laboratory LLC > Columbus, Ohio > http://www.srl-llc.com > A picture is worth a thousand emails, so: <http://www.srl-llc.com/files/capture12032008_3.png> multiple sources at ~0 dBm... one source at ~-117dBm... -- Phil Covington Software Radio Laboratory LLC Columbus, Ohio http://www.srl-llc.com _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
Re: K3 & ADAT ADT-200A by HB9CBU
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In reply to this post by Don Wilhelm-4
Technology is wonderful, but I still have an extreme reluctance to adopt any kind of SDR that is based on general purpose computers. The main reason is lifespan: most ham radios have a useful life of 20 or 30 years, even if not in the hands of the original purchaser, and that is considerably longer than the lifetime of any computer operating system. I would not want to make an investment in some equipment that would become obsolescent because the software needed is no longer available to run on current PCs and operating systems. It would be like the problem we currently have with printers, scanners etc. that still work but have to be thrown away because there are no XP or Vista drivers. Other than that there is the simple fact that general purpose computers are not as stable as dedicated hardware and you have all the hassle of keeping them free of viruses etc. It doesn't really matter whether you use Windows or Linux - having used both I find them equally abominable. I don't really care what goes on inside the box but I want my radio in a box marked "radio" with its own independent controls, that works separately from any computer. So, personally, I hope that SDR will evolve in the direction of having some dedicated hardware platform that runs the SDR software, inside the box of the radio - as the K3 does, even if it is not a fully software defined radio as is being discussed here.
Julian, G4ILO. K2 #392 K3 #222 KX3 #110
* G4ILO's Shack - http://www.g4ilo.com * KComm - http://www.g4ilo.com/kcomm.html * KTune - http://www.g4ilo.com/ktune.html |
Re: K3 & ADAT ADT-200A by HB9CBU
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In a recent message, "Julian, G4ILO" <[hidden email]> wrote ...
>I don't really care what goes on inside the box but I want my radio in a box >marked "radio" with its own independent controls, that works separately from >any computer. I do concur with that, Julian, which is why I have not gone for the LP-PAN option. When the K3 was launched I was given to understand that Elecraft would be producing an add-on panadapter in the future. I would prefer to wait for that. 73 -- David G4DMP Leeds, England, UK ------ _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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In reply to this post by Julian, G4ILO
Hello Julian,
> Technology is wonderful, but I still have an extreme reluctance to adopt any > kind of SDR that is based on general purpose computers... The one of the interesting things about using personal computers for SDR is imho that generally more people can take part in their development in major or minor ways. This is why I just recently decided to purchase the QS1R - it is open source, which, if I so decide, will allow me to tinker with it. I've got a hankering to unite a panadapter with information from the WinTest band map, DX-cluster spots and maybe a few other goodies. No idea when and if I'll actually do this, but with this kind of an open system I (much more easily) can if I want. I understand your concern about the rapid rate of obsolescent in the PC world. I would argue that with a clever choice of which interface to use, some concepts will actually survive many hard- and software cycles. This way at least the hardware of the radio wouldn't have to be changed. The software would likely be less stable, but otoh as the hardware becomes more powerful, newer software come become more complex and offer new features. > Other than that there is the simple fact that general purpose computers are > not as stable as dedicated hardware and you have all the hassle of keeping > them free of viruses etc... The easy answer is: Never fix a working system, don't install anything you don't really need and don't use the computer for anything else. But then we are getting close a dedicated solution. > I don't really care what goes on inside the box but I want my radio in a box > marked "radio" with its own independent controls... I personally dislike black boxes. I want to know about what is going on inside. The choice of user interface has a lot to do with what one wants to do with the radio, and is one one of the reasons I really love my K3. That being said, if you have ever worked in a well designed professional video editing suite or control room, then you soon realize that while much of equipment on the market do have reasonable user interfaces, they are not nearly as good as they could be. Especially when you look at the sum of all equipment in the average shack. It often has to do with little things, like what position does your wrist have to be in to push a button, move a slider, how far do I have to move my hands to perform an operation and how many steps are involved, etc. Adding knobs, buttons and putting the SDR in a box may or may not be the best way to go. vy 73 de toby _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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Hi Larry,
>> I have lots of experience with video editing suites, both traditional, and >> high end workstation based systems. They each have their advantages, and I >> haven't noticed any speed advantage for either when it comes to >> post-production. When it comes to live production, however, buttons and >> knobs win hands down IMO. The point is not so much *if* buttons, sliders, knobs and the like are better, but how the operating controls are arranged. For example, I would hate to think of doing a live edit of a sports event if everything is mounted a vertical plane. Otoh, I was involved in a live sports magazine show, which was produced in a virtual studio - this would not have been possible without a context sensitive GUI on a computer screen. For a contest situation I would like a little of both, especially if my hands do not have to "wander" around to operate various parts of the station and at the same time do the logging. vy 73 de toby PPS: Amazing how my innocent question whether the ADT-200A had been tested somewhere, has resulted in a wonderful thread dealing with many aspects of modern radio design... _______________________________________________ Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
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Yes, it has been an informative thread indeed. I considered weighing in,
but everything seemed to be covered in excellent detail. I will say that, based on my measurements, a much bigger issue today is transmitter performance rather than receiver performance. The main culprit is of course synthesizer noise, but splatter and key clicks are also contributors. I have pictures from my panadapter, which uses a xtal oscillator LO, of an analog signal generator feeding the panadapter directly at about S9+80dB. The picture is clean as a whistle. The same signal going through the K3 shows some spreading of the signal within a few kHz due to the effect of the synthesizer. The noise floor degradation is a modest 10dB at 2 kHz, and none at 5kHz.. The same setup, fed by a signal from my TS-480S is unbelievable. The noise floor jumps about 25 dB, and extends tens of kHz either side of the signal. A signal 2kHz from the TS-480S would have to be S9+10dB to be heard! On the interface, I love having the option of controlling the K3 by hand or through one of the connected programs. to me, it's the best of both worlds. Good point about virtual studio. I retired just before they came into vogue. 73, Larry N8LP Toby Deinhardt wrote: > Hi Larry, > >>> I have lots of experience with video editing suites, both >>> traditional, and >>> high end workstation based systems. They each have their advantages, >>> and I >>> haven't noticed any speed advantage for either when it comes to >>> post-production. When it comes to live production, however, buttons and >>> knobs win hands down IMO. > > The point is not so much *if* buttons, sliders, knobs and the like are > better, but how the operating controls are arranged. For example, I > would hate to think of doing a live edit of a sports event if > everything is mounted a vertical plane. > > Otoh, I was involved in a live sports magazine show, which was > produced in a virtual studio - this would not have been possible > without a context sensitive GUI on a computer screen. > > For a contest situation I would like a little of both, especially if > my hands do not have to "wander" around to operate various parts of > the station and at the same time do the logging. > > vy 73 de toby > > PPS: Amazing how my innocent question whether the ADT-200A had been > tested somewhere, has resulted in a wonderful thread dealing with many > aspects of modern radio design... > Elecraft mailing list Post to: [hidden email] You must be a subscriber to post to the list. Subscriber Info (Addr. Change, sub, unsub etc.): http://mailman.qth.net/mailman/listinfo/elecraft Help: http://mailman.qth.net/subscribers.htm Elecraft web page: http://www.elecraft.com |
Re: K3 & ADAT ADT-200A by HB9CBU
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In reply to this post by dj7mgq
> The one of the interesting things about using personal computers for SDR is > imho that generally more people can take part in their development in major > or minor ways. This is why I just recently decided to purchase the QS1R I can understand the attraction of that for hams, just as I understand the attraction of Linux for people interested in what makes computers work. But from what I have seen of open source type development the old adage about too many hands can spoil the broth come to mind. Like anything designed by a committee, it can take ages to get anything done. There is a lot to be said for having things developed exclusively by a dedicated and focussed team, as in the case of Microsoft. > I understand your concern about the rapid rate of obsolescent in the PC > world. I would argue that with a clever choice of which interface to use, > some concepts will actually survive many hard- and software cycles. This way > at least the hardware of the radio wouldn't have to be changed. The software > would likely be less stable, but otoh as the hardware becomes more powerful, > newer software come become more complex and offer new features. I was really more concerned with what support there will be for the current generation of SDR radios in, say 10 years time. If the PC that runs the current software dies, and you can't get a new PC that runs XP (or whatever you need to run that SDR software) what guarantee do you have that any software that runs on Windows 2020 or whatever will support the 10 year old box. The manufacturer (if they are still around) will probably have no interest in supporting obsolete products. > I personally dislike black boxes. I want to know about what is going on > inside. What I really meant by that was that I don't care if it is SDR or analog, as long as it does what I want. But having said that, and having read this discussion and seen some of the terminology used, I realize that for me, DSP technology is way over my head. I understand how analog radios like the K2 work. I understand how most of the K3 works, but there are some black boxes marked "DSP". Once you start digitising the entire HF spectrum, how you get from that to your voice coming out of my speaker is beyond me, and probably beyond most people without a math PhD. > The choice of user interface has a lot to do with what one wants to do with > the radio, and is one one of the reasons I really love my K3. I agree, but if you keep the radio separate from the computer and provide some sort of CAT interface programmers can create any UI that you want, without having to get involved in the SDR side of things.
Julian, G4ILO. K2 #392 K3 #222 KX3 #110
* G4ILO's Shack - http://www.g4ilo.com * KComm - http://www.g4ilo.com/kcomm.html * KTune - http://www.g4ilo.com/ktune.html |
Re: K3 & ADAT ADT-200A by HB9CBU
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That should have been "as in the case of Elecraft"!
Julian, G4ILO. K2 #392 K3 #222 KX3 #110
* G4ILO's Shack - http://www.g4ilo.com * KComm - http://www.g4ilo.com/kcomm.html * KTune - http://www.g4ilo.com/ktune.html |
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In reply to this post by Nico Palermo, IV3NWV
Nico, this is truly exceptional phase noise performance! My sincerest congratulations to you. Have you described how you achieved this somewhere?
73, Bill W4ZV
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