K3 IF/AF Dsp questions (comparisons)
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K3 IF/AF Dsp questions (comparisons)
 
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The 756pro has no roofing filters, yet there is little
or no AGC pumping when listening to an S2 signal with the DSP filter set to 500hz and a S9 signal is within the 15khz first hardware filter. I'm hoping the K3 can do at least this well without switching in a roofing filter of less than 2.7khz. The TenTec Argo V will pump somewhat in the same scenario and pump very hard in a contest, at times swamping the receiver. It's a great radio for a quiet afternoon or contesting with modest antennas. The TS480Sat will pump dramatically and you need to leave the 500hz filter in line anytime there is an S9 signal within the 2.8khz ssb filter. The 500hz filter is superb for selectivity but adds a very high level of background noise when the bands are not quiet. _______________________________________________ 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 IF/AF Dsp questions (comparisons)
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Don,
I don't think the concern here is with S9 signals, but rather much stronger ones. Here is a clip from Erics article talking about roofing filters...... If you only use the 2.7 kHz stock filter for CW or data operation you will be significantly desensed once signals within that filter's bandwidth exceed about S9+25. Hope that helps... 73 Greg AB7R On Wed, 16 May 2007 14:23:54 -0700 (PDT) Don Rasmussen <[hidden email]> wrote: > The 756pro has no roofing filters, yet there is little > or no AGC pumping when listening to an S2 signal with > the DSP filter set to 500hz and a S9 signal is within > the 15khz first hardware filter. I'm hoping the K3 can > do at least this well without switching in a roofing > filter of less than 2.7khz. > > The TenTec Argo V will pump somewhat in the same > scenario and pump very hard in a contest, at times > swamping the receiver. It's a great radio for a quiet > afternoon or contesting with modest antennas. > > The TS480Sat will pump dramatically and you need to > leave the 500hz filter in line anytime there is an S9 > signal within the 2.8khz ssb filter. The 500hz filter > is superb for selectivity but adds a very high level > of background noise when the bands are not quiet. > _______________________________________________ > 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 IF/AF Dsp questions (comparisons)
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Right, Greg. We're talking about VERY strong signals here.
For example: This is why dynamic range is so important to 6m contesters. Signals on 6m during intense sporadic-E (Es) openings can be incredibly strong, due both to the shorter ionospheric path for this kind of propagation and to the high efficiency of Es clouds as radio wave reflectors. (Es clouds tend to be both intensely ionized and very planar, like a reflecting mirror as compared to a refracting atmospheric layer as in F2 propagation.) Signals of 40 dB to 50 dB over S9 are fairly common on 6m during a hot contest Es opening. But readable signals on 6m can also be very weak, as the atmospheric noise floor is significantly lower on this band than on the HF bands, and copying a signal producing only a half-microvolt at the receiver front end is not unrealistic in the absence of man-made RFI or thunderstorms. When you're talking about trying to copy this 0.5 uv S1 signal in the presence of 40-over-9 signals 5 and 10 kHz away (again, a common real-world scenario on 6m during a contest), you're looking at a range of 40 dB + ( 8 S-units x 5 dB/S-unit ) = 80 dB. Just as a reality factor, my Kenwood TS-2000 has been measured by ARRL Labs to have a 5 kHz 3rd-order IMD dynamic range at 50.1 MHz of a scintillating 66 dB. OUCH! This isn't even close. A 25-over-9 signal would still push the envelope of the receiver's IMD dynamic range, and signals of that strength are all over the band on 6m during the June contest. I can tell you from experience that using a receiver with 66 dB @ 5 kHz DR3 is painful. You really can't hear weak signals if strong signals are within 10 kHz or more of your operating frequency. Which is why I'm awaiting my K3 with bated breath. Too bad it won't be here in time for the ARRL June VHF, but I'm still holding out some faint hope for the July CQWW VHF. I'm in the first-production-run queue. ;-) Bill / W5WVO FISCHER,GREG wrote: > Don, > > I don't think the concern here is with S9 signals, but > rather much stronger ones. Here is a clip from Erics > article talking about roofing filters...... > > If you only use the 2.7 kHz stock filter for CW or data > operation you will be significantly desensed once signals > within that filter's bandwidth exceed about S9+25. > > Hope that helps... > > 73 > Greg > AB7R > > > > On Wed, 16 May 2007 14:23:54 -0700 (PDT) > Don Rasmussen <[hidden email]> wrote: >> The 756pro has no roofing filters, yet there is little >> or no AGC pumping when listening to an S2 signal with >> the DSP filter set to 500hz and a S9 signal is within >> the 15khz first hardware filter. I'm hoping the K3 can >> do at least this well without switching in a roofing >> filter of less than 2.7khz. >> >> The TenTec Argo V will pump somewhat in the same >> scenario and pump very hard in a contest, at times >> swamping the receiver. It's a great radio for a quiet >> afternoon or contesting with modest antennas. >> >> The TS480Sat will pump dramatically and you need to >> leave the 500hz filter in line anytime there is an S9 >> signal within the 2.8khz ssb filter. The 500hz filter >> is superb for selectivity but adds a very high level >> of background noise when the bands are not quiet. >> _______________________________________________ >> 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 _______________________________________________ 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 IF/AF Dsp questions (comparisons)
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On May 16, 2007, at 5:01 PM, Bill W5WVO wrote:
> When you're talking about trying to copy this 0.5 uv S1 signal in > the presence of 40-over-9 signals 5 and 10 kHz away (again, a > common real-world scenario on 6m during a contest), you're looking > at a range of 40 dB + ( 8 S-units x 5 dB/S-unit ) = 80 dB. 6dB per S-unit is the standard. That would make it a 48dB+40dB or 88dB. That takes a really good receiver. 73 de Brian, WB6RQN Brian Lloyd - brian HYPHEN wb6rqn AT lloyd DOT 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 IF/AF Dsp questions (comparisons)
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In reply to this post by Don Rasmussen
Hi Brian,
Well... The REAL standard, the one that EVERYBODY agrees on, is that S9 = 50 uV. How many dB an S-unit is depends on where you start from to get there. Let's say that an S-unit is 6 dB and that the minimum detectable signal (MDS) is 0.25 uV. That's probably about where the MDS of the K3 is going to come in, plus or minus a few hundredths. How many dB between 0.25 uV and 50 uV? The formula is dB = 20log(V1/V2), so dB = 20log(200) = 46 dB. At 6 dB per S unit, that's 7.67 S-units below S9, or about S1-and-a-third. That means that a signal that you can just barely distinguish from the receiver's own internal noise floor -- i.e., essentially the amplitude of the receiver's internal noise floor itself -- is over S1 on the meter. That doesn't make intuitive sense to me. A more reasonable S-unit is about 5 dB. Why? You put the 0.25 uV MDS at S0 so that you get 46 dB / 5 dB/S-unit = ~9 S-units. This means that anything above the MDS moves the S-meter, including any atmospheric noise level that rises above MDS. A no-signal condition (i.e., the antenna is disconnected) is S0, no meter deflection -- where it should be, IMHO. 6 dB per S-unit might have been somebody's standard way back when, but as you can see, it doesn't really make sense. If you really want a calibrated S-meter, I think you have to go with 5 dB, unless you want to number the scale from S1 "on the pin" (or actually a little below the "pin"). Maybe that's acceptable. Depends on how you think about it. I like 5 dB better because it makes better technical and intuitive sense to me. My guess is that the K3 will come with some default value for an S-unit, but that it will also be user-settable in the menu. Based on a conversation I had with Wayne a couple weeks back, that default will NOT be 6 dB. I'm hoping I convinced him that 5 dB (as opposed to something lower) is a good number, by the logic given above. 5 dB also works well because it is a modulus of 10, 15, 20, etc., which gives a more pleasing symmetry to "dB over S9". In short -- Since there really isn't an existing S-meter calibration standard that anybody agrees on and is currently using, we might as well set a standard that makes some sense. I suspect that the K3 will be setting standards all over the place. :-) Bill Brian Lloyd wrote: > On May 16, 2007, at 5:01 PM, Bill W5WVO wrote: > >> When you're talking about trying to copy this 0.5 uv S1 signal in >> the presence of 40-over-9 signals 5 and 10 kHz away (again, a >> common real-world scenario on 6m during a contest), you're looking >> at a range of 40 dB + ( 8 S-units x 5 dB/S-unit ) = 80 dB. > > 6dB per S-unit is the standard. That would make it a 48dB+40dB or > 88dB. That takes a really good receiver. > > 73 de Brian, WB6RQN > Brian Lloyd - brian HYPHEN wb6rqn AT lloyd DOT 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 IF/AF Dsp questions (comparisons)
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In reply to this post by Bill VanAlstyne W5WVO
On May 16, 2007, at 7:52 PM, Bill W5WVO wrote:
> Hi Brian, > > Well... The REAL standard, the one that EVERYBODY agrees on, is > that S9 = 50 uV. How many dB an S-unit is depends on where you > start from to get there. I agree. OTOH, the initial description was that we were comparing an S1 signal with an S9+40dB signal. But you are certainly right that, if there is a standard, 50uV into 50ohms represents S9. > Let's say that an S-unit is 6 dB and that the minimum detectable > signal (MDS) is 0.25 uV. That's probably about where the MDS of the > K3 is going to come in, plus or minus a few hundredths. How many dB > between 0.25 uV and 50 uV? The formula is dB = 20log(V1/V2), so dB > = 20log(200) = 46 dB. At 6 dB per S unit, that's 7.67 S-units below > S9, or about S1-and-a-third. That means that a signal that you can > just barely distinguish from the receiver's own internal noise > floor -- i.e., essentially the amplitude of the receiver's internal > noise floor itself -- is over S1 on the meter. That doesn't make > intuitive sense to me. > > A more reasonable S-unit is about 5 dB. Why? You put the 0.25 uV > MDS at S0 so that you get 46 dB / 5 dB/S-unit = ~9 S-units. This > means that anything above the MDS moves the S-meter, including any > atmospheric noise level that rises above MDS. A no-signal condition > (i.e., the antenna is disconnected) is S0, no meter deflection -- > where it should be, IMHO. 6 dB per S-unit might have been > somebody's standard way back when, but as you can see, it doesn't > really make sense. Well, like everything else, it is an arbitrary standard. To be honest with you I have always stuck with 6dB/S-unit as the standard and S0 being the receiver's noise floor but that doesn't take into account the receiver's bandwidth which could affect the level of the MDS. 50uV into 50 ohm representing S9 makes sense for a single carrier but might not be valid for a more complex signal. And I have never found a receiver that had a calibrated S-meter. I get a kick out of guys turning on their amplifier that provides 10dB of gain and seeing a 4 s-unit increase. Makes no sense but it sure makes them feel good when I report it that way. (Actually I now just tell them that it made a 1.5 s-unit difference. :-) > If you really want a calibrated S-meter, I think you have to go > with 5 dB, unless you want to number the scale from S1 "on the > pin" (or actually a little below the "pin"). Maybe that's > acceptable. Depends on how you think about it. I like 5 dB better > because it makes better technical and intuitive sense to me. I certainly understand. OTOH, I believe that even the FCC question pool refers to an S-unit as being 6dB. I also did a search on the web and found references to 6dB/s-unit. It does make some sense as each S- unit represents a two-fold voltage change, something easily determined when looking at a signal with a 'scope or a meter. > My guess is that the K3 will come with some default value for an S- > unit, but that it will also be user-settable in the menu. Based on > a conversation I had with Wayne a couple weeks back, that default > will NOT be 6 dB. I'm hoping I convinced him that 5 dB (as opposed > to something lower) is a good number, by the logic given above. 5 > dB also works well because it is a modulus of 10, 15, 20, etc., > which gives a more pleasing symmetry to "dB over S9". Aw, that's just marking the meter face. :-) > In short -- Since there really isn't an existing S-meter > calibration standard that anybody agrees on and is currently using, > we might as well set a standard that makes some sense. I suspect > that the K3 will be setting standards all over the place. :-) That certainly makes sense. 73 de Brian, WB6RQN Brian Lloyd - brian HYPHEN wb6rqn AT lloyd DOT 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 |
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In reply to this post by Bill VanAlstyne W5WVO
> When you're talking about trying to copy this 0.5 uv S1 signal in the
> presence of 40-over-9 signals 5 and 10 kHz away (again, a common > real-world scenario on 6m during a contest), you're looking at a range > of 40 dB + ( 8 S-units x 5 dB/S-unit ) = 80 dB. Minor niggle: 1 S-Unit = 6dB http://www.algonet.se/~k-jarl/ssa/IARU/smeter.html ------------------------------------------------------------------------ STANDARDISATION OF S-METER READINGS 1. One S-unit corresponds to a signal level difference of 6 dB, 2. On the bands below 30 MHz a meter deviation of S-9 corresponds to an available power of -73 dBm from a continuous wave signal generator connected to the receiver input terminals, 3. On the bands above 144 MHz this available power shall be -93 dBm, 4. The metering system shall be based on quasi-peak detection with an attack time of 10 msec ± 2 msec and a decay time constant of at least 500 msec. ------------------------------------------------------------------------ One does wonder about the bands between 10m and 2m..... http://www.giangrandi.ch/electronics/radio/smeter/smeter.html (Zc = 50 Ohm) S1 -48 dB 0.20 uV -14 dBuV 790 aW -121 dBm S2 -42 dB 0.40 uV -8 dBuV 3.2 fW -115 dBm S3 -36 dB 0.79 uV -2 dBuV 13 fW -109 dBm S4 -30 dB 1.6 uV 4 dBuV 50 fW -103 dBm S5 -24 dB 3.2 uV 10 dBuV 200 fW -97 dBm S6 -18 dB 6.3 uV 16 dBuV 790 fW -91 dBm S7 -12 dB 13 uV 22 dBuV 3.2 pW -85 dBm S8 -6 dB 25 uV 28 dBuV 13 pW -79 dBm S9 0 dB 50 uV 34 dBuV 50 pW -73 dBm S9+10 10 dB 160 uV 44 dBuV 500 pW -63 dBm S9+20 20 dB 500 uV 54 dBuV 5.0 nW -53 dBm S9+30 30 dB 1.6 mV 64 dBuV 50 nW -43 dBm S9+40 40 dB 5.0 mV 74 dBuV 500 nW -33 dBm S9+50 50 dB 16 mV 84 dBuV 5.0 uW -23 dBm S9+60 60 dB 50 mV 94 dBuV 50 uW -13 dBm (Zc = 50 Ohm) S1 -48 dB 20 nV -34 dBuV 7.9 aW -141 dBm S2 -42 dB 40 nV -28 dBuV 32 aW -135 dBm S3 -36 dB 79 nV -22 dBuV 130 aW -129 dBm S4 -30 dB 160 nV -16 dBuV 500 aW -123 dBm S5 -24 dB 320 nV -10 dBuV 2.0 fW -117 dBm S6 -18 dB 630 nV -4 dBuV 7.9 fW -111 dBm S7 -12 dB 1.3 uV 2 dBuV 32 fW -105 dBm S8 -6 dB 2.5 uV 8 dBuV 130 fW -99 dBm S9 0 dB 5.0 uV 14 dBuV 500 fW -93 dBm S9+10 10 dB 16 uV 24 dBuV 5.0 pW -83 dBm S9+20 20 dB 50 uV 34 dBuV 50 pW -73 dBm S9+30 30 dB 160 uV 44 dBuV 500 pW -63 dBm S9+40 40 dB 500 uV 54 dBuV 5.0 nW -53 dBm S9+50 50 dB 1.6 mV 64 dBuV 50 nW -43 dBm S9+60 60 dB 5.0 mV 74 dBuV 500 nW -33 dBm 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 |
Re: K3 IF/AF Dsp questions (comparisons)
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In reply to this post by Brian Lloyd-6
Brian Lloyd wrote:
> I agree. OTOH, the initial description was that we were comparing an > S1 signal with an S9+40dB signal. Right. I wrote, "...this 0.5 uV S1 signal..." Actually, at 5 dB per S-unit and S0 = MDS (0.25 uV), S1 would be about 0.44 uV... But hey, that's reasonably close to 0.5. ;-) Well, enough on this topic, I suppose, before somebody comes over here and pins my coax. Or more to the point, cuts my DSL line. <g> 73, Bill / W5WVO _______________________________________________ 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 Bill VanAlstyne W5WVO
Hi Bill,
> How many dB an S-unit is depends on where you start from to get there. Nope. At least on our side of the puddle IARU Region 1 Technical Recommendation R.1 defines how many dB a S-unit is. One S-Unit *is* 6dB. If the K3 is not 6dB per S-Unit, then yet again another useless S-meter in the eyes of many (if not most) amateurs over here. 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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Toby,
Interesting. OK, I wasn't aware of that. Over here, it's a source of endless debate (a bit of which I was engaging in). I'm quite certain there are no US standards for an S-unit (IEEE, ANSI, etc.) Could be wrong, but I've never heard anybody claim such. I guess we give Wayne et al. a chance to get back from Dayton and see what they have to say about it. I know Wayne wasn't very keen about a 6 dB S-unit when I talked with him earlier, but maybe he isn't aware of this IARU Region 1 spec, either. Thanks for giving us the reference. If 6 dB is indeed a recognized standard in at least part of the known world, I'd have no trouble accepting that calibration on the K3. I still say 5 dB makes more technical and intuitive sense, but no point in bucking the established world order. :-) Bill / W5WVO Toby Deinhardt wrote: > Hi Bill, > >> How many dB an S-unit is depends on where you start from to get >> there. > > Nope. At least on our side of the puddle IARU Region 1 Technical > Recommendation R.1 defines how many dB a S-unit is. > > One S-Unit *is* 6dB. > > If the K3 is not 6dB per S-Unit, then yet again another useless > S-meter in the eyes of many (if not most) amateurs over here. > > 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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In my 56 years of hamming I've always thought the "standard" was/is
6 db, but I can't site anything support this. We Yanks have always resisted the "world order" when it comes to measurements ..... Lessee, the last I knew it was just us and Libya holding out ... 73! Ken Kopp - K0PP [hidden email] _______________________________________________ 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 dj7mgq
> One does wonder about the bands between 10m and 2m.....
I just found a newer document, with a corrected version of Recommendation R.1. http://www.iaru-r1.org/VHF_Handbook_V5_11.pdf IARU Region VHF Managers Handbook Version 5.11, 07. 08. 2006 Page 156 -------------------------------------------------------------------------- IARU Region 1 Technical Recommendation R.1 BRIGHTON 1981, TORREMOLINOS 1990 STANDARDISATION OF S-METER READINGS 1. One S-unit corresponds to a signal level difference of 6 dB, 2. On the bands below 30 MHz a meter deviation of S-9 corresponds to an available power of -73 dBm from a continuous wave signal generator connected to the receiver input terminals, 3. On the bands above 30 MHz this available power shall be -93 dBm, 4. The metering system shall be based on quasi-peak detection with an attack time of 10 msec ∀ 2 msec and a decay time constant of at least 500 msec. -------------------------------------------------------------------------- _______________________________________________ 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 IF/AF Dsp questions (comparisons)
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In reply to this post by Brian Lloyd-6
Brian Lloyd <[hidden email]>
wrote on Thursday, May 17, 2007 at 4:37 AM > And I have never found a receiver that had a calibrated S-meter. Oh that's the reason for "You are S9, what's your call , name and my report again please?" Perhaps it's time for S meters to be calibrated in input dbm? Chaos during contests! 73, Geoff GM4ESD _______________________________________________ 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 IF/AF Dsp questions (comparisons)
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> Brian Lloyd <[hidden email]>
> wrote on Thursday, May 17, 2007 at 4:37 AM > > > And I have never found a receiver that had a calibrated S-meter. > TS-480SAT it not at all bad - in fact it's my favourite HF radio for many reasons (a K3 is on order). My IC-7800 had an accurate S-Meter as well (IC-7800 sold some months ago). Simon 'I only need one K3' HB9DRV _______________________________________________ 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 Geoffrey Mackenzie-Kennedy-2
There is never ever any moment during a contest, with the exception of
the first/last half hour on high band openings/closing, where the rx signals drop below S9. If not, you're antenna situation really sucks big-time. Go visit a contest station sometime and find out. The signal report during contests is useless unless you would state your exact location, terrain environment, antenna type and height, AND have a calibrated s-meter. During a normal qso things (just) might be totally different and so is your goal. Let's stop the ever lasting "59 in contests" discussion. '73 Mark PA5MW > > Oh that's the reason for "You are S9, what's your call , name and my > report again please?" > > Perhaps it's time for S meters to be calibrated in input dbm? Chaos > during contests! > _______________________________________________ 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 Ken Kopp
I've heard the 6dB per S unit figure in conversations for years, but
I've never seen it written in any authoritative source. However, I note that Collins receivers from the 50s and 60s, having S meters marked in both dB and S units, seem to indicate that 3 S units = 10 dB, equivalent to a nice round 3.33 dB per S unit. Bob K4ERR Ken Kopp wrote: > In my 56 years of hamming I've always thought the "standard" was/is > 6 db, but I can't site anything support this. > > We Yanks have always resisted the "world order" when it comes to > measurements ..... Lessee, the last I knew it was just us and Libya > holding out ... > > 73! Ken Kopp - K0PP > [hidden email] > > _______________________________________________ > 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 |
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It would be easier just to dump the 6db per S unit
scale and do what the professionals do, that is use the DbUV scale. You could then have readings in precise 3db steps. Most new military receivers are now calibrated in DbuV. However with the advent of new generation of Software Defined radios like Flexradio 5000, you can have 1db accuracy on your S meter. The RFSPACE SDR14 likewise allows for accurate level readings. I believe the Omni 7 also has an calibrated S meter. Collins confused things by specifying 100 uv for S9, however that was open circuit voltage not across 50 ohms which was later adopted by the IARU. There is still some confusion today about the 100 microvolt versus the 50 microvolt level. Kenwood specifies 100 microvolts for S 9 and others 50uv. We should just dump all these innacurate methods and get inline with commercial practice. Once your S meter is caibrated in DbUV it would be easy to have an alternate scale in S units thats both reliable and accurate. However since the K3 was the last great hope in innovative analogue engineering, we just have to accept that its S meter is not calibrated. Craig VK3HE --- rrkrr <[hidden email]> wrote: > I've heard the 6dB per S unit figure in > conversations for years, but > I've never seen it written in any authoritative > source. However, I note > that Collins receivers from the 50s and 60s, having > S meters marked in > both dB and S units, seem to indicate that 3 S units > = 10 dB, equivalent > to a nice round 3.33 dB per S unit. > > Bob K4ERR > > Ken Kopp wrote: > > In my 56 years of hamming I've always thought the > "standard" was/is > > 6 db, but I can't site anything support this. > > > > We Yanks have always resisted the "world order" > when it comes to > > measurements ..... Lessee, the last I knew it was > just us and Libya > > holding out ... > > > > 73! Ken Kopp - K0PP > > [hidden email] > > > > _______________________________________________ > > 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 > ____________________________________________________________________________________Take the Internet to Go: Yahoo!Go puts the Internet in your pocket: mail, news, photos & more. http://mobile.yahoo.com/go?refer=1GNXIC _______________________________________________ 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 IF/AF Dsp questions (comparisons)
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In reply to this post by Brian Lloyd-6
> Well... The REAL standard, the one that EVERYBODY agrees on, is > that S9 = 50 uV. How many dB an S-unit is depends on where you > start from to get there. Everyone except the receiver (and transceiver) manufacturers. If you run a curve of S-meter reading vs input voltage using a calibrated generator, you will find that it's close to 6dB/S-unit around S9, but close to 3 dB/S-unit when you get below S6 or S7. And I'm not talking about "junk" receivers -- I've done this with some very good radios, like TS850's and FT1000MP's. No, I haven't done it with my K2's. Someday. 73, Jim Brown K9YC _______________________________________________ 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 Craig-89
I agree that 5 dB per S-unit makes good engineering sense. Sorry to the
standards group, but 6 db per s-unit just doesn't add up. Having the S-meter at S-1.5 with the antenna disconnected? Can we say useless? With modern rigs, it would be a fairly simple matter for the manufacturer to use the DSP to correct the s-meter. AGC may not be linear but the DSP could compensate and provide a corrected drive for the meter that would provide S-0 with no signal, S-9 at 50 uV and a pretty even 5 db per s-unit between there. If that were done and if the user knew it was 5 per unit, then we'd be able to actually start using the s-meters to indicate something more than just "you have signal". S-meters are only useless because they've been built that way for too many years. - Keith N1AS - - SKCC 344c - _______________________________________________ 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 rrkrr-2
Hi Bob,
> I've never seen it written in any authoritative source. For example: IARU Region 1 VHF Managers Handbook Version 5.11, 07. 08. 2006 http://www.iaru-r1.org/VHF_Handbook_V5_11.pdf Page 156 IARU Region 1 HF Managers Handbook Version 6.0, January 2007 http://www.iaru-r1.org/HFM%20Handbook%20V6.pdf Page 141 (11.1.2-1) vy 73 de toby -- DD5FZ, 4N6FZ (ex dj7mgq, dg5mgq, dd5fz) K2 #885, K2/100 #3248 K3/100 #??? (< #200) DOK C12, BCC, DL-QRP-AG _______________________________________________ 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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