Re: Topband: One Way Propagation.
Replacing T at RS(T) reporting with N (Noise floor) RSN could be more precise reading. 73, Agelos SV3RF _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
Re: Topband: One Way Propagation.
Finally some common sense, thanks Luke! Rich - W4RQ Amateur Radio: The Original Social Media > On Jan 17, 2021, at 20:26, List Mail wrote: > > I have been using HPSDR in my station for the past ten or so years, and like > Flex SDR, the S-meter does not change with application of attenuator. The > signal strength changes between the transmitting antenna and receiving > antennas of course, so IMO it's absolute value is largely irrelevant. > > I also find somewhat bemusing the lengthy signal reports I hear between > stations "with Preamp 1, with Preamp 2" etc., usually on 40 m SSB. > > My on air reports usually pay little heed to what the "S-Meter" is reading, > apart from noting the band noise strength compared with the signal strength. > S-Meters are mostly a gimmick, with relevance only in laboratory bench > testing. My use of the RST is generally in accordance with the verbal > description of signals, i.e., Readability 1 = Unreadable to 5 = Perfectly > readable; Signal Strength 1 = Faint signals, barely perceptible to 9 = > Extremely strong signals. Don't start me on people giving "0 and 1 or 2" > signal reports, and then conducting a conversation. And where the heck does > the "Audio Only report, NO Signal strength" come from? > > Back to the OT, I often receive very lopsided signal reports, usually with > FT8 (sometimes a 30 dB lower report received than given) and less often in > SSB or CW. Sometimes it is in my favour, sometimes my QSO partner. As long as > we can complete our QSO, with a few of the traditional niceties, I don't lose > any sleep over the differential. I live in a quiet rural location, with > plenty of room for antennas, and the nearest neighbour is some 500 metres > away, so I hear better than most. Sometimes I call a relatively strong > station, and don't get any response at all, and wonder if my antenna has > fallen down. I put it down to the other station listening in a different > direction, and/or having QRM/QRN. I move on. > > 73, Luke VK3HJ > _ > Searchable Archives: http://www.contesting.com/_topband - Topband Reflector _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
Re: Topband: One Way Propagation.
I have been using HPSDR in my station for the past ten or so years, and like Flex SDR, the S-meter does not change with application of attenuator. The signal strength changes between the transmitting antenna and receiving antennas of course, so IMO it's absolute value is largely irrelevant. I also find somewhat bemusing the lengthy signal reports I hear between stations "with Preamp 1, with Preamp 2" etc., usually on 40 m SSB. My on air reports usually pay little heed to what the "S-Meter" is reading, apart from noting the band noise strength compared with the signal strength. S-Meters are mostly a gimmick, with relevance only in laboratory bench testing. My use of the RST is generally in accordance with the verbal description of signals, i.e., Readability 1 = Unreadable to 5 = Perfectly readable; Signal Strength 1 = Faint signals, barely perceptible to 9 = Extremely strong signals. Don't start me on people giving "0 and 1 or 2" signal reports, and then conducting a conversation. And where the heck does the "Audio Only report, NO Signal strength" come from? Back to the OT, I often receive very lopsided signal reports, usually with FT8 (sometimes a 30 dB lower report received than given) and less often in SSB or CW. Sometimes it is in my favour, sometimes my QSO partner. As long as we can complete our QSO, with a few of the traditional niceties, I don't lose any sleep over the differential. I live in a quiet rural location, with plenty of room for antennas, and the nearest neighbour is some 500 metres away, so I hear better than most. Sometimes I call a relatively strong station, and don't get any response at all, and wonder if my antenna has fallen down. I put it down to the other station listening in a different direction, and/or having QRM/QRN. I move on. 73, Luke VK3HJ _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
Topband: One Way Propagation.
I must admit, that even when I started out on Top Band 50 years ago, and my CR100 Receiver didn't have an S Meter, I think I was pretty good at estimating how strong signals were (ie how many uV were arriving at my front end) by the position of the RF gain ! But once I had a commercial rig with a decent S Meter, I always made sure they were properly calibrated . . . ie that S9 corresponded to 50uV, and that each S Point was around 6 dB. And would always give proper signal strength reports. (as I find most people do these days) And I totally agree with you Greg . . . somebody can be perfectly readable yet only S1 on a very quiet band (like 10m) . . . or S8 but be unreadable, due to a high noise level on 160m ! (this is why I find S/N reports - like RBN gives - pretty meaningless . . . what I really want to know is how strong my signal is!) But anyway . . . coming back to my original question . . . I wonder how often others have noticed a big disparity between Sent and Received signals on Top Band? The best examples are when you work the same DX station regularly, and you know that you USUALLY exchange similar reports . . . ie when he is S5, that's what you are with him . . . when he gives you S9, he's S9 with you (and you know conditions are good!) But every so often he might be S3, yet he's giving you S8 . . . or vice-versa. Some have said this sometimes happens around Sunrise or Sunset . . . but I actually tend to avoid those times these days, as far from being any PEAK (like there always used to be), there is often a DROP in signals. So I sometimes notice this disparity in the middle of the night . . . which I obviously can't explain . . . but then again 160m Propagation has always been a bit of a mystery ! Roger G3YRO _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
Re: Topband: One Way Propagation.
Comment below On 1/17/2021 11:09 AM, Wes wrote: I'm not going to smack this tar baby, other than to note that Elecraft is a special case with respect to S-meters. K3(S) have an "Absolute" mode that compensates for preamp gain or input attenuation. So the S-meter becomes a decent power meter. I think it's unconscionable that other manufactures, with microprocessor controlled radios, haven't incorporated this. The fact that certain features appear in certain radios and not in others may lie in the "intellectual property" . Mfg A is unwilling to sell the rights to a particular feature to competitor Mfg B or at least is unwilling to sell below a price that will compensate A for the loss in sales gained by B because they now have this feature too. Or B cant afford to recover the higher "cost" in enough added sales.? There are at least two sides to every story, often more, ...The truth lies somewhere in between. Dave NR1DX -- Dave manu...@artekmanuals.com www.ArtekManuals.com -- This email has been checked for viruses by Avast antivirus software. https://www.avast.com/antivirus _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
Re: Topband: One Way Propagation.
Then with FT8, the "db" rating depends on S/N not signal power. I hear well so my report is most frequently better than received. The big guns are an exception with well engineered stations in good locations. However, FT8 "db's" being S/N do wash out the gain loss when using Rx antennas. Of course, my Flex computation of the power in an FT8 band segment is totally meaningless. Grant KZ1W On 1/17/2021 08:22, Michael Walker wrote: All Flex radios measure signal strength regardless of the PreAmp settings. As well, they correctly calculate the power in the receiving passband. Early superhet radios use maxim signal that was rectified into a DC voltage to provide an S meter reading and to also drive the AGC. This is why when the AGC is off, there are no S meter readings. (that is the simple way to describe it). It is also likely that they are not well calibrated other than to show that S9 is -73dbm and plus or minus that is not what you think it should be. The 'S' value is also calculated based on the 50ohm input level at the receiver, not the antenna. This will also result in different readings from different users since antenna systems are all different. In the end, the information is for reference only and is useful for comping changes at your own station. Now, if SNR was actually reported then stations could start to compare similar readings. Mike va3mw On Sun, Jan 17, 2021 at 11:10 AM Wes wrote: I'm not going to smack this tar baby, other than to note that Elecraft is a special case with respect to S-meters. K3(S) have an "Absolute" mode that compensates for preamp gain or input attenuation. So the S-meter becomes a decent power meter. I think it's unconscionable that other manufactures, with microprocessor controlled radios, haven't incorporated this. They should be fully capable of measuring their own preamp gain and attenuator loss and compensating the meter accordingly. I throw into this criticism the TS-890 that I just acquired. My goodness, they went to the effort to incorporate a decoder for PSK, of all things, but can't provide a decently calibrated S-meter. Wes N7WS On 1/17/2021 7:26 AM, Don Kirk wrote: Hi Roger, Signal report comparisons with the modern radios that often have preamps that you can switch in or out really clouds the picture as well as the fact most stations on topband use RX antennas. Assuming that all manufacturers have S meters that are calibrated identical to each other (which is not the case), the big question is if the S meter calibration was done with the preamp on or off, and if the person that is giving you a signal report has the preamp on or off. As an example the Elecraft S meter uses the common standard of S9 = 50 uV but the calibration is done with Preamp 1 on. And when a station is using an RX antenna everything goes out the window since RX antennas often have very negative gain, and then if an external preamp is being used that adds another variable. And if just using a TX antenna for receive there is a lot of difference in each stations antenna effective gain (due to ground losses, etc.) that adds another variable. A signal report of S2 or S6 tells me nothing on how well I am being heard since I need to know what your noise floor is too (unless you are telling me how many S units above your noise floor I am ). What helps me the most is to understand how many dB above your noise floor I am, and that is why you will see that when I spot a station on DX Summit, I say how many dB the station is peaking and that means how many dB above my noise floor the station is peaking (I think this is similar to what you see for signal reports on the RBN). Just FYI, Don (wd8dsb) On Sun, Jan 17, 2021 at 8:04 AM Roger Kennedy < ro...@wessexproductions.co.uk> wrote: Well personally I always give Signal Strength reports from my S Meter . . . So it doesn't matter whether my Noise Level is S2 or S6 . . . I'm telling you how strong your signal is at my QTH. Roger G3YRO _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
Re: Topband: One Way Propagation.
All Flex radios measure signal strength regardless of the PreAmp settings. As well, they correctly calculate the power in the receiving passband. Early superhet radios use maxim signal that was rectified into a DC voltage to provide an S meter reading and to also drive the AGC. This is why when the AGC is off, there are no S meter readings. (that is the simple way to describe it). It is also likely that they are not well calibrated other than to show that S9 is -73dbm and plus or minus that is not what you think it should be. The 'S' value is also calculated based on the 50ohm input level at the receiver, not the antenna. This will also result in different readings from different users since antenna systems are all different. In the end, the information is for reference only and is useful for comping changes at your own station. Now, if SNR was actually reported then stations could start to compare similar readings. Mike va3mw On Sun, Jan 17, 2021 at 11:10 AM Wes wrote: > I'm not going to smack this tar baby, other than to note that Elecraft is > a > special case with respect to S-meters. K3(S) have an "Absolute" mode that > compensates for preamp gain or input attenuation. So the S-meter becomes a > decent power meter. > > I think it's unconscionable that other manufactures, with microprocessor > controlled radios, haven't incorporated this. They should be fully > capable of > measuring their own preamp gain and attenuator loss and compensating the > meter > accordingly. I throw into this criticism the TS-890 that I just > acquired. My > goodness, they went to the effort to incorporate a decoder for PSK, of all > things, but can't provide a decently calibrated S-meter. > > Wes N7WS > > > On 1/17/2021 7:26 AM, Don Kirk wrote: > > Hi Roger, > > > > Signal report comparisons with the modern radios that often have preamps > > that you can switch in or out really clouds the picture as well as the > fact > > most stations on topband use RX antennas. Assuming that all > manufacturers > > have S meters that are calibrated identical to each other (which is not > the > > case), the big question is if the S meter calibration was done with the > > preamp on or off, and if the person that is giving you a signal report > has > > the preamp on or off. As an example the Elecraft S meter uses the common > > standard of S9 = 50 uV but the calibration is done with Preamp 1 on. And > > when a station is using an RX antenna everything goes out the window > since > > RX antennas often have very negative gain, and then if an external preamp > > is being used that adds another variable. And if just using a TX antenna > > for receive there is a lot of difference in each stations antenna > effective > > gain (due to ground losses, etc.) that adds another variable. > > > > A signal report of S2 or S6 tells me nothing on how well I am being heard > > since I need to know what your noise floor is too (unless you are telling > > me how many S units above your noise floor I am ). What helps me the > > most is to understand how many dB above your noise floor I am, and that > is > > why you will see that when I spot a station on DX Summit, I say how many > dB > > the station is peaking and that means how many dB above my noise floor > the > > station is peaking (I think this is similar to what you see for signal > > reports on the RBN). > > > > Just FYI, > > Don (wd8dsb) > > > > On Sun, Jan 17, 2021 at 8:04 AM Roger Kennedy < > ro...@wessexproductions.co.uk> > > wrote: > > > >> Well personally I always give Signal Strength reports from my S Meter . > . > >> . > >> > >> So it doesn't matter whether my Noise Level is S2 or S6 . . . I'm > telling > >> you how strong your signal is at my QTH. > >> > >> Roger G3YRO > >> > >> > >> _ > >> Searchable Archives: http://www.contesting.com/_topband - Topband > >> Reflector > >> > > _ > > Searchable Archives: http://www.contesting.com/_topband - Topband > Reflector > > > _ > Searchable Archives: http://www.contesting.com/_topband - Topband > Reflector > _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
Re: Topband: One Way Propagation.
I'm not going to smack this tar baby, other than to note that Elecraft is a special case with respect to S-meters. K3(S) have an "Absolute" mode that compensates for preamp gain or input attenuation. So the S-meter becomes a decent power meter. I think it's unconscionable that other manufactures, with microprocessor controlled radios, haven't incorporated this. They should be fully capable of measuring their own preamp gain and attenuator loss and compensating the meter accordingly. I throw into this criticism the TS-890 that I just acquired. My goodness, they went to the effort to incorporate a decoder for PSK, of all things, but can't provide a decently calibrated S-meter. Wes N7WS On 1/17/2021 7:26 AM, Don Kirk wrote: Hi Roger, Signal report comparisons with the modern radios that often have preamps that you can switch in or out really clouds the picture as well as the fact most stations on topband use RX antennas. Assuming that all manufacturers have S meters that are calibrated identical to each other (which is not the case), the big question is if the S meter calibration was done with the preamp on or off, and if the person that is giving you a signal report has the preamp on or off. As an example the Elecraft S meter uses the common standard of S9 = 50 uV but the calibration is done with Preamp 1 on. And when a station is using an RX antenna everything goes out the window since RX antennas often have very negative gain, and then if an external preamp is being used that adds another variable. And if just using a TX antenna for receive there is a lot of difference in each stations antenna effective gain (due to ground losses, etc.) that adds another variable. A signal report of S2 or S6 tells me nothing on how well I am being heard since I need to know what your noise floor is too (unless you are telling me how many S units above your noise floor I am ). What helps me the most is to understand how many dB above your noise floor I am, and that is why you will see that when I spot a station on DX Summit, I say how many dB the station is peaking and that means how many dB above my noise floor the station is peaking (I think this is similar to what you see for signal reports on the RBN). Just FYI, Don (wd8dsb) On Sun, Jan 17, 2021 at 8:04 AM Roger Kennedy wrote: Well personally I always give Signal Strength reports from my S Meter . . . So it doesn't matter whether my Noise Level is S2 or S6 . . . I'm telling you how strong your signal is at my QTH. Roger G3YRO _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
Topband: One Way Propagation.
Well whether people have an accurate S Meter is another debate altogether ! If ever I'm working somebody on SSB, and they are S9 +20 with me, but they tell me I'm just S8, I ask them if they have an Attenuator switched in or their Preamp switched off . . . when I point out that their rig's S Meter only reads correctly with the Preamp on, they are often surprised . . . and then turn it on to give me a proper report ! However . . . most people I find DO give accurate reports . . . (and I think most 160m DX operators are intelligent enough to know how to make their S Meter read correctly.) So I find that with most of the general QSOs I get the same reports as I am giving . . . hence my pointing out that it's curious when 160m DX propagation is such that signals are much stronger one way than the other. Regarding using separate Receiving Antennas . . . well I have a Preamp on my 160m Receiving Loop, which is set so that local signals are exactly the same strength as on my Transmitting Antenna . . . in that way I can give meaningful reports, regardless of which antenna I am using. Regarding how strong your signal is above my Noise Level, to me that's kind of meaningless to the other station . . . in practice my Noise Level can vary between S3 and S8 . . . but surely you want to know how strong your signal is with me? (and using RBN highlights this, as it only says how strong your signal is above their noise level . . . so if the figure is low, is that because propagation is poor tonight, or just that they have a high noise level, due to static, etc?) Roger G3YRO _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
Re: Topband: One Way Propagation.
Hi Roger, Signal report comparisons with the modern radios that often have preamps that you can switch in or out really clouds the picture as well as the fact most stations on topband use RX antennas. Assuming that all manufacturers have S meters that are calibrated identical to each other (which is not the case), the big question is if the S meter calibration was done with the preamp on or off, and if the person that is giving you a signal report has the preamp on or off. As an example the Elecraft S meter uses the common standard of S9 = 50 uV but the calibration is done with Preamp 1 on. And when a station is using an RX antenna everything goes out the window since RX antennas often have very negative gain, and then if an external preamp is being used that adds another variable. And if just using a TX antenna for receive there is a lot of difference in each stations antenna effective gain (due to ground losses, etc.) that adds another variable. A signal report of S2 or S6 tells me nothing on how well I am being heard since I need to know what your noise floor is too (unless you are telling me how many S units above your noise floor I am ). What helps me the most is to understand how many dB above your noise floor I am, and that is why you will see that when I spot a station on DX Summit, I say how many dB the station is peaking and that means how many dB above my noise floor the station is peaking (I think this is similar to what you see for signal reports on the RBN). Just FYI, Don (wd8dsb) On Sun, Jan 17, 2021 at 8:04 AM Roger Kennedy wrote: > > Well personally I always give Signal Strength reports from my S Meter . . > . > > So it doesn't matter whether my Noise Level is S2 or S6 . . . I'm telling > you how strong your signal is at my QTH. > > Roger G3YRO > > > _ > Searchable Archives: http://www.contesting.com/_topband - Topband > Reflector > _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
Re: Topband: One Way Propagation.
Roger Lucky you! My S meter rarely goes below S4( on the BOG) and S8 on the transmit antenna .. In the context of measuring one way propagation there is the purist's dilemma of receiving antenna signal level vs transmit antenna signal level ? Dave NR1DX On 1/17/2021 8:04 AM, Roger Kennedy wrote: Well personally I always give Signal Strength reports from my S Meter . . . So it doesn't matter whether my Noise Level is S2 or S6 . . . I'm telling you how strong your signal is at my QTH. Roger G3YRO _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector -- Dave manu...@artekmanuals.com www.ArtekManuals.com -- This email has been checked for viruses by Avast antivirus software. https://www.avast.com/antivirus _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
Topband: One Way Propagation.
Well personally I always give Signal Strength reports from my S Meter . . . So it doesn't matter whether my Noise Level is S2 or S6 . . . I'm telling you how strong your signal is at my QTH. Roger G3YRO _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
Re: Topband: One Way Propagation.
Here is the one possible explanation in my old article http://www.k3bu.us/propagation.htm 73 Yuri, K3BU, VE3BMV, VE1BY etc. > On January 16, 2021 at 6:20 PM Roger Kennedy > wrote: > > > > If you have an efficient transmitting antenna, and an accurately calibrated > S Meter, I have found over the decades that most signal reports are pretty > Reciprocal. > > When it comes to 160m DX-ing, I think my own situation is fairly unusual, in > that my Receiving Antenna is also my Transmitting Antenna. (being a dipole, > it's fairly low noise on Receive) > > And as a result, 90% of the time I have found that my signal reports on Top > Band are pretty much the same both ways . . . and that's whether working > stations around Britain, around Europe, across the pond to North or South > America (including to the West Coast), even the Far East or VK/ZL. > > Last night when I worked Jeff VY2ZM he said my signal was peaking S9 +20dB . > . . and he was the same strength with me. > > But what prompted me to start a new discussion was receiving an mail from a > station in Arizona who said I was 579 with him last night . . . but I didn't > come back to him. Well, my noise level was around S3 last night, and I did > hear a couple of stations down in the noise calling me . . . which means > that he was far weaker with me than I was with him. > > And thinking about it, this happens quite often on Top Band. Not only is > Propagation often VERY selective (meaning someone 200 miles away may have > much better propagation to a particular area than you) . . . but also that > sometimes the Propagation is ONE-WAY . . . that you're receiving them far > weaker than they're receiving you, or the other way round. > > I wonder if many DX-ers on here have noticed the same phenomenon . . . > particularly those that often work the same stations many times (as I do). > > 73 Roger G3YRO > > _ > Searchable Archives: http://www.contesting.com/_topband - Topband Reflector _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
Re: Topband: One Way Propagation.
On 1/16/2021 3:20 PM, Roger Kennedy wrote: If you have an efficient transmitting antenna, and an accurately calibrated S Meter, I have found over the decades that most signal reports are pretty Reciprocal. 73 Roger G3YRO Even if: 1. Propagation were always reciprocal. and 2. Everyone had a calibrated S meter and 3. Everyone used a single antenna for RX and TX and 4. Everyone had the same noise level in their environment. There would still be no guarantee that equal S meter readings would correspond to equal S/N ratios. For example, you transmit and receive on a dipole, which is generally better on RX. If the station at the other end is (like me) transmitting and receiving on a vertical, that will make me seem to be an alligator. Of course, conditions 1 through 4 are by no means assured in the first place. YMMV. 73 Rick N6RK _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
Re: Topband: One Way Propagation.
Hi Roger, The experience I share with the few Gs with whom I regularly have QSOs is that the propagation is more often better one way than the other. At my SS, via LP, I hear them better than they me, and vice versa at my SR. It's not always the case, but is more often than not. 73, Greg, ZL3IX On 2021-01-17 12:20, Roger Kennedy wrote: If you have an efficient transmitting antenna, and an accurately calibrated S Meter, I have found over the decades that most signal reports are pretty Reciprocal. When it comes to 160m DX-ing, I think my own situation is fairly unusual, in that my Receiving Antenna is also my Transmitting Antenna. (being a dipole, it's fairly low noise on Receive) And as a result, 90% of the time I have found that my signal reports on Top Band are pretty much the same both ways . . . and that's whether working stations around Britain, around Europe, across the pond to North or South America (including to the West Coast), even the Far East or VK/ZL. Last night when I worked Jeff VY2ZM he said my signal was peaking S9 +20dB . . . and he was the same strength with me. But what prompted me to start a new discussion was receiving an mail from a station in Arizona who said I was 579 with him last night . . . but I didn't come back to him. Well, my noise level was around S3 last night, and I did hear a couple of stations down in the noise calling me . . . which means that he was far weaker with me than I was with him. And thinking about it, this happens quite often on Top Band. Not only is Propagation often VERY selective (meaning someone 200 miles away may have much better propagation to a particular area than you) . . . but also that sometimes the Propagation is ONE-WAY . . . that you're receiving them far weaker than they're receiving you, or the other way round. I wonder if many DX-ers on here have noticed the same phenomenon . . . particularly those that often work the same stations many times (as I do). 73 Roger G3YRO _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
Topband: One Way Propagation.
If you have an efficient transmitting antenna, and an accurately calibrated S Meter, I have found over the decades that most signal reports are pretty Reciprocal. When it comes to 160m DX-ing, I think my own situation is fairly unusual, in that my Receiving Antenna is also my Transmitting Antenna. (being a dipole, it's fairly low noise on Receive) And as a result, 90% of the time I have found that my signal reports on Top Band are pretty much the same both ways . . . and that's whether working stations around Britain, around Europe, across the pond to North or South America (including to the West Coast), even the Far East or VK/ZL. Last night when I worked Jeff VY2ZM he said my signal was peaking S9 +20dB . . . and he was the same strength with me. But what prompted me to start a new discussion was receiving an mail from a station in Arizona who said I was 579 with him last night . . . but I didn't come back to him. Well, my noise level was around S3 last night, and I did hear a couple of stations down in the noise calling me . . . which means that he was far weaker with me than I was with him. And thinking about it, this happens quite often on Top Band. Not only is Propagation often VERY selective (meaning someone 200 miles away may have much better propagation to a particular area than you) . . . but also that sometimes the Propagation is ONE-WAY . . . that you're receiving them far weaker than they're receiving you, or the other way round. I wonder if many DX-ers on here have noticed the same phenomenon . . . particularly those that often work the same stations many times (as I do). 73 Roger G3YRO _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
Re: Topband: one-way propagation
On my 80 meter NTS net last evening (1830 local time) I noticed that the critical frequency had dropped below 3.5 MHz. I could barely hear some stations that were only 40 miles away and my neighbor Claire N7CM reported that she heard no one but me. (No problem working 5T0SP, however, which entirely made up for the hard time that I had running the net.) When this happened in the past -- the last time was in Dec 2009 -- condx on 160 were often very good over the pole from here to EU. I haven't heard EU yet this season, but here's hoping! 73, Carl WS7L Last weekend was (finally) a return of over-the-pole conditions in my QTH, > similar to what we experienced frequently in 2009 and 2010. I could hear > ___ Topband reflector - topband@contesting.com
Re: Topband: one-way propagation
Last weekend was (finally) a return of over-the-pole conditions in my QTH, similar to what we experienced frequently in 2009 and 2010. I could hear western NA stations ALL day here, some with very good signals despite full daylight at my end. They did not fade out until sunrise over there >14.00 GMT. Everyone I heard was coming in via SP, true beam heading across the pole. I called many stations, repeatedly for long periods of time. Some signals were peaking 559/569 in the rather slow QSB. Not even a QRZ in return, except for VY2ZM, we worked at 1014 GMT. One way propagation? No, I don't think so. I think that the fact I was not heard was just the difference in noise levels at both ends. Probably adding to that, the NA stations heard were using receive antennas that were pointed anywhere BUT to the North pole. On moonbounce I experience one way propagation very often. But then I can mathematically explain why, it has to do with so called spatial offset and a 45 degree Faraday rotation. No mystery, just a sound explanation because of geometry. There are times during strong auroras when I can hear European stations on low bands pretty well in the evenings but they can't hear me. Again, at those times I am sure it is due to the noise level a the other end. If signals are depressed by aurora up here at 65.4 N then the crud on the band is also depressed. So I hear stations at S3-5 levels very well. But they are probably seeing the normal >S7 evening time noise background, masking my signals completely. However, in contests, like the first night of CQ WW CW a couple of weeks ago, it was frustrating to operate on 160m in the aurora. Even when doing S/P it was difficult to work stations in northern Europe, although I heard them very well at S2-3 levels. So, I don't think that there is a magic situation where one-way-propagation exists on HF, it should be fully reciprocal. In my opinion it's rather a result of different noise situations at both ends. 73 de Peter SM2CEW At 22:08 2012-12-04 , Mike Waters wrote: >I've often thought that some "one-way propagation" is simply due to the >differences in antennas. For example, two stations with the same power, >ambient noise level, etc. are receiving on Beverages pointed at each other, >but their TX antennas have different takeoff angles and/or patterns. For >example. station A with an NVIS antenna (like a low horizontal loop) might >hear station B who is transmitting on a vertical, but maybe not vice versa. > >73, Mike >www.w0btu.com >___ >Topband reflector - topband@contesting.com > ___ Topband reflector - topband@contesting.com
Re: Topband: one- way propagation
Here some interesting paper about LF MF polarization http://www.ann-geophys.net/22/1705/2004/angeo-22-1705-2004.pdf This paper, High-latitude propagation studies using a meridional chain of LF/MF/HF receivers I stop reading when I get to this point: "The receivers used in this study involve one of two antenna types: electric or magnetic dipoles. In both cases, the antenna is nonresonant at all frequencies detected. The electric dipole consists of a 3m vertical rod elevated approximately 3m above the ground. The magnetic dipole consists of a 10-m2 magnetic loop antenna oriented vertically at an angle which nulls out the strongest local interference signal." When the methodology is questionable or wrong, why should we trust the results? 1.) To receive horizontally polarized waves at a reasonable wave angle (compared to a vertical) requires either a substantial antenna design to suppress vertical component and high angle components, or it requires the horizontally polarized antenna be exactly broadside to the arriving signal and at least 1/2 wave above earth. 2.) Response levels to be equal, or compensated. A "magnetic loop" is radially polarized. At various angles and directions polarization changes. It is entirely vertical in some directions, and horizontal in others, and tilted polarization at most angles and directions. Even a dipole has that problem. A dipole is only perfectly horizontally polarized directly broadside to the dipole. Off the ends, it is vertically polarized. QST ran some articles about X-O stuff that was equally flawed in concept and methodology. Measuring polarization is easy on upper HF or higher where wavelength is short and a horizontal antenna can be rotated broadside and placed at reasonable heights. It is nearly impossible for most people below 40 meters. When the basic sensors used for measurements are seriously flawed, there isn't much reason to read the results. 73 Tom ___ Topband reflector - topband@contesting.com
Re: Topband: one-way propagation
It just goes to show that what looks good on paper in theory does not mean it HAS to be the same in the real world. There is nothing to prevent 2 signals a continent away and with different antennas from taking completely different paths when one is at either sunset or sunrise. There hasnt been a book written yet to explain it all. On a different note there was no way anyone would have believed that it was possible to work JA on 6M at the bottom of the cycle from New England yet several of us made the trip starting a few years ago. Experts are still arguing about that mechanism while on here one stands on a platform (not you Carl) and expects everything said to be believed without question. Carl KM1H - Original Message - From: "Carl Clawson" To: "topband" Sent: Tuesday, December 04, 2012 6:22 PM Subject: Re: Topband: one-way propagation Yes, a good point that I neglected. This entirely circumvents my yammerings about reciprocity. Reciprocity is a characteristic of a single pair of ports in a network. Introducing separate receive antennas can surely cause a one way effect. Consider what happens when I hook up a dummy load as a Rx antenna ... 73 and thanks for listening, Carl WS7L I've often thought that some "one-way propagation" is simply due to the differences in antennas. For example, two stations with the same power, ambient noise level, etc. are receiving on Beverages pointed at each other, but their TX antennas have different takeoff angles and/or patterns. ___ Topband reflector - topband@contesting.com - No virus found in this message. Checked by AVG - www.avg.com Version: 10.0.1427 / Virus Database: 2634/5436 - Release Date: 12/04/12 ___ Topband reflector - topband@contesting.com
Re: Topband: one- way propagation
Jose, Interesting paper, I'll have to poor over it some more to digest it. Thanks, Jim, KR9U -Original Message- From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of N4IS Sent: Tuesday, December 04, 2012 9:05 PM To: 'Doug Renwick'; 'Robert Briggs'; topband@contesting.com Subject: Re: Topband: one- way propagation Here some interesting paper about LF MF polarization http://www.ann-geophys.net/22/1705/2004/angeo-22-1705-2004.pdf This paper, High-latitude propagation studies using a meridional chain of LF/MF/HF receivers >> Fig. 5. (a) Polarization of 50-5000 kHz signals recorded at Churchill, Manitoba, on 1-2 October 1997. White pixels indicate left-hand polarization, black pixels indicate right-hand polarization, and gray pixels indicate indeterminant polarization. (b) Power spectral density of the same 50-5000 kHz signals. Received signals above 1MHz are predominantly left-hand polarized except in the interval 09:00-12:00UT, 1-4 h before sunrise, when righthand waves dominate at frequencies above about 3Mhz. >> Figure 5 shows a possibly related effect occuring near the dawn terminator but involving wave polarization. The bottom panel shows a spectrogram of 50-5000 kHz signals recorded at Churchill, Manitoba, for 20 h, starting at 20:00 UT on 1 October 1997, a geomagnetically quiet day for which the signals show the usual diurnal pattern. >> 7'3 N4IS JC ___ Topband reflector - topband@contesting.com ___ Topband reflector - topband@contesting.com
Re: Topband: one- way propagation
Here some interesting paper about LF MF polarization http://www.ann-geophys.net/22/1705/2004/angeo-22-1705-2004.pdf This paper, High-latitude propagation studies using a meridional chain of LF/MF/HF receivers >> Fig. 5. (a) Polarization of 50-5000 kHz signals recorded at Churchill, Manitoba, on 1-2 October 1997. White pixels indicate left-hand polarization, black pixels indicate right-hand polarization, and gray pixels indicate indeterminant polarization. (b) Power spectral density of the same 50-5000 kHz signals. Received signals above 1MHz are predominantly left-hand polarized except in the interval 09:00-12:00UT, 1-4 h before sunrise, when righthand waves dominate at frequencies above about 3Mhz. >> Figure 5 shows a possibly related effect occuring near the dawn terminator but involving wave polarization. The bottom panel shows a spectrogram of 50-5000 kHz signals recorded at Churchill, Manitoba, for 20 h, starting at 20:00 UT on 1 October 1997, a geomagnetically quiet day for which the signals show the usual diurnal pattern. >> 7'3 N4IS JC ___ Topband reflector - topband@contesting.com
Re: Topband: one- way propagation
Doug > Nope, Nope. I am a firm believer in one-way propagation on 160m, having witnessed it many times. > Can we agree, that we disagree.? When the signal is going up the polarization does not matter because after the first refraction the signal become elliptical, that's why the DX station independent of the polarization of the signal arriving here , always can copy me. I also witnessed many times the DX signal arriving only horizontal, including signals from. If the DX signal is arriving horizontal you won't be able to copy using your 4 SQ. even a high dipole does not do it because the dipole has no directivity, The RDF is very low, a dipole is not a receiver antenna. The fact you can't copy the signal does not mean that it is not there. It is special true for LP when I can copy signals very strong on the horizontal WV via SSW and not a single beep on the vertical HF, During the last 2 season I worked XU7ACY on 160m over 15 times (logging a QSO) ,and heard him way over 60 times, only with horizontal polarization. Same thing happened several times with Bobby VK3ZL, and it is not the local noise level. 73's JC N4IS ___ Topband reflector - topband@contesting.com
Re: Topband: one- way propagation
an added note/comment here During the XZ0A expedition, I think we conclusively proved that: 1: Skew paths exist and are repeatable 2: the arrival angle of the signals is NOT reciprocal. The arrival angle of the XZ0A signal as heard in the eastern/central US was reasonably normal, and extended into sunrise in the way we have generally come to expect, Direct angle measurements were, of course, not made, and are unlikely to be measurable except by inference. The arrival angle of the signals from NA as heard at XZ0A were clearly and repeatedly very high. Beverage antennas did NOT hear the signals, whereas a very low dipole heard the signals fine, and repeatedly, night after night. the point is that if we received exclusively on the beverages, we would have an apparent difference in signal strength of at least 15 dB - the apparent level of the signal arriving at XZ0A would be 15 dB less than the XZ0A signal as measured in NA, with comparable transmit ERP. TX was 2KW into a full size elevated radials quarter wave (a 200 ft tower with an insulator a quarter wave down from the top) this TX level is comparable to many higher performance stations in NA and significantly less ERP than some stations with large TX arrays, The noise floor was definitely an issue, us being in the middle of Asia, BUT, when there is 20 dB difference between the signal heard on ANY beverage, and the signal heard on a full size dipole at 10 ft, its pretty conclusive that the pattern of the antennas was a serious effect. The relative noise level heard on the dipole was still quite a lot higher than we would have liked- the Asia noise propagates at high angles as well as low ones, but was comparable to the beverage noise floor, less some directive effects the point is, the path is NOT symmetrical. A number of complex explanations have been put forth, and I'm waiting for occams razor to slice down to the meat. Robin Critchell, WA6CDR (XZ0A XZ1N VP6DX) - Original Message - From: "Doug Renwick" To: "'Robert Briggs'" ; Sent: Tuesday, December 04, 2012 17:14 Subject: Re: Topband: one- way propagation Nope, Nope. I am a firm believer in one-way propagation on 160m, having witnessed it many times. Let me give you a recent example. In the last weekends contest I worked LY7M. We both run decent stations. We exchanged emails after including actual signal strength. Saulius copied me 579; I copied him 539 with my 4-square. When I called he came right back to me. QRN, QRM, QSB were not a factor at my end. Often I will hear a weak EU station calling CQ will little response. I call and I am copied immediately. Anecdotal you say. True but many times experience trumps theory. Doug -Original Message- Interesting theories and observations regarding one way propagation..My take is that most of the seemingly one way prop is more dependent on operator skill and the local qrn at one end of the circuit..With the current conditions this past 12 months most usually strong signals on the band are often attenuated due to less than a reliable path..I hear many signals that may be only S1-3and few hear a station calling them..These conditions may give the impression of "one way" prop but it is more likely due to qrn conditions at the listening end...I am looking at this from the VK cross the Equator Summer/Winter differences which have a big influence on making a contact..My observations over 35 years show that there is propagation most of the time all year if stations take the time and patience to listen for DX.. Bob..VK3ZL.. ___ Topband reflector - topband@contesting.com ___ Topband reflector - topband@contesting.com ___ Topband reflector - topband@contesting.com
Re: Topband: one- way propagation
Nope, Nope. I am a firm believer in one-way propagation on 160m, having witnessed it many times. Let me give you a recent example. In the last weekends contest I worked LY7M. We both run decent stations. We exchanged emails after including actual signal strength. Saulius copied me 579; I copied him 539 with my 4-square. When I called he came right back to me. QRN, QRM, QSB were not a factor at my end. Often I will hear a weak EU station calling CQ will little response. I call and I am copied immediately. Anecdotal you say. True but many times experience trumps theory. Doug -Original Message- Interesting theories and observations regarding one way propagation..My take is that most of the seemingly one way prop is more dependent on operator skill and the local qrn at one end of the circuit..With the current conditions this past 12 months most usually strong signals on the band are often attenuated due to less than a reliable path..I hear many signals that may be only S1-3and few hear a station calling them..These conditions may give the impression of "one way" prop but it is more likely due to qrn conditions at the listening end...I am looking at this from the VK cross the Equator Summer/Winter differences which have a big influence on making a contact..My observations over 35 years show that there is propagation most of the time all year if stations take the time and patience to listen for DX.. Bob..VK3ZL.. ___ Topband reflector - topband@contesting.com ___ Topband reflector - topband@contesting.com
Re: Topband: one-way propagation
Tom, I don't think anyone takes issue with the concept of propagated noise raising the noise level on one side of the QSO while the other side is still quiet. Anyone who looks for it will see it if their QTH is relatively quiet, and I regularly see the 10-15 dB variation you've often cited. But what Carl has cited here was apparently serious scientific observation that showed a difference of nearly 10dB. That's a lot, and if they were measuring field strength and not signal to noise ratio, it means that there's something going on that we haven't figured out yet. That observation is one important part of the scientific process. Another part is starting from that observation and trying to understand why. Many times in my life I've observed something through careful observation, then worked to try to understand it. Our concept of reciprocity applies to linear systems that are time-invariant, and, just as with a wired network of passive components, the source and termination impedances are part of the network. With propagation, it's generally well known that the signal path can mess with polarization, and it's not hard to believe that that effect could be different in different directions. 73, Jim K9YC On 12/4/2012 2:09 PM, Tom W8JI wrote: I can't recall anyone who has made a study of this citing that as a reason for non-reciprocity, and Carl's recent post about a broadcast study said the effect someone reported seeing was only on a west-east path and no one knew why. The reasons theorists have cited have only to due with gyrorotation. I'm not saying you are wrong, but what have they missed to not bring the issues you highlight up? In all of the conditions you mention, what specific mechanism causes a path to be non-reciprocal at any instant of time? I know why things like lossy networks can be non-reciprocal in impedance, but what is the mechanism at work? ___ Topband reflector - topband@contesting.com
Re: Topband: one-way propagation
Jim > Is your WF horizontal antenna much higher than the vertical? < Yes, the HWF boom is at 116ft and the VWF=BWF as I used to call it , the boon is at 50ft Both antennas has RDF of 11.5 db, the HWF has 44 ft boom and the VWF has 50 ft, but almos the same negative gain, and high F/B and F/S the same too. The HWF has two horizontal loops cancelling each other, end feed, as a result the takeoff angle is 36 degree and there is a deep null from signals coming from the side and from 90 degree, same as F/S for the vertical WF(VWF). Regards JC -Original Message- From: N4IS [mailto:n...@comcast.net] Sent: Tuesday, December 04, 2012 6:18 PM To: jbw...@comcast.net; 'Tom W8JI'; topband@contesting.com Subject: RE: Topband: one-way propagation Jim Not always, polarization plays a lot on 160m, in special W-E E-W. Sometimes a signal from Africa dive on the QSB and disappear from the Vertical WF and switching to the horizontal WF the signal is peaking, other times I only can hear the DX signal horizontal. I don't call this unidirectional because I use a vertical TX all the time and the DX hears me well even the signal is arriving horizontal. Regards Jose Carlos N4IS -Original Message- From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of James Wolf Sent: Tuesday, December 04, 2012 3:41 PM To: 'Tom W8JI'; topband@contesting.com Subject: Re: Topband: one-way propagation Tom, It is a known that the ionosphere is not a perfect sphere. It is always moving and it is lumpy and tilted. Together these occurrences can cause focusing and defocusing of the wave due to deformities especially if they are concave or convex. One-way-propagation can reveal itself as a deep and/or prolonged fade on only one end of the link because of the aforementioned reasons.Of course fades can be caused by other reasons, such as multiple paths, etc. Jim, KR9U -Original Message- From: Tom W8JI [mailto:w...@w8ji.com] Sent: Tuesday, December 04, 2012 6:45 AM To: jbw...@comcast.net; topband@contesting.com Subject: Re: Topband: one-way propagation > To expand a little on Carl's explanation, the ionosphere is not as > isotropy as we commonly imagine - in that it is not a nice smooth > balloon shaped surface to bounce a signal off of. Instead, there are > varying degrees of irregularity, not unlike a sandy desert where the > wind moves the landscape around and creates moving peaks and valleys. > So imagine the ionosphere in this condition when a signal from one > direction has a nice reflection down to the receiver, but in the other > direction, it is reflected at a different angle and lands somewhere else. > > Jim, KR9U > There is no possible combination of refractions or reflections that is not reciprocal in both directions. If there is a mechanism at work, it is at an entirely different level than simple multiple reflections. After 50 years on 160, I'm still unsure if one way propagation exists. All of the "one way" I have seen and taken the time to look at involves noise levels, QRM, or just the capability of the stations. For example, prior to sunset here my local noise is very low. Even on a quiet winter night in a quiet direction, noise floor increases 10-15 dB as it gets darker and conditions improve. I can hear Europeans that I have no hope of working (on 40 meters this happens all day long). Their noise is high (even in a quiet location) because it is dark. As it gets darker their signals come up, and so does my noise and QRM, but eventually they hear me. The opposite occurs at sunrise. There is the same noise floor drop after daylight. This means I can hear JA's working west coast stations long after they stop being able to hear me. Local storms and local QRM, and the direction of that stuff, is also is a huge factor in reciprocity. Sorting it all out is very complicated, and involves far more than observing "sometimes people at one end don't answer". Sorting it out would involve and **require** calibrated observations of absolute signal levels and noise levels at both ends. I think this is why one way prop is, at best, arguable. 73 Tom ___ Topband reflector - topband@contesting.com ___ Topband reflector - topband@contesting.com
Re: Topband: one-way propagation
Carlos, That is also true. The incident wave when entering into the ionosphere splits into two elliptically polarized waves, and are likely in opposite polarization from each other as well as having different amplitudes. As someone else mentioned, the W-E E-W is a phenomenon we don't understand yet. Is your WF horizontal antenna much higher than the vertical? Jim, KR9U -Original Message- From: N4IS [mailto:n...@comcast.net] Sent: Tuesday, December 04, 2012 6:18 PM To: jbw...@comcast.net; 'Tom W8JI'; topband@contesting.com Subject: RE: Topband: one-way propagation Jim Not always, polarization plays a lot on 160m, in special W-E E-W. Sometimes a signal from Africa dive on the QSB and disappear from the Vertical WF and switching to the horizontal WF the signal is peaking, other times I only can hear the DX signal horizontal. I don't call this unidirectional because I use a vertical TX all the time and the DX hears me well even the signal is arriving horizontal. Regards Jose Carlos N4IS -Original Message- From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of James Wolf Sent: Tuesday, December 04, 2012 3:41 PM To: 'Tom W8JI'; topband@contesting.com Subject: Re: Topband: one-way propagation Tom, It is a known that the ionosphere is not a perfect sphere. It is always moving and it is lumpy and tilted. Together these occurrences can cause focusing and defocusing of the wave due to deformities especially if they are concave or convex. One-way-propagation can reveal itself as a deep and/or prolonged fade on only one end of the link because of the aforementioned reasons.Of course fades can be caused by other reasons, such as multiple paths, etc. Jim, KR9U -Original Message- From: Tom W8JI [mailto:w...@w8ji.com] Sent: Tuesday, December 04, 2012 6:45 AM To: jbw...@comcast.net; topband@contesting.com Subject: Re: Topband: one-way propagation > To expand a little on Carl's explanation, the ionosphere is not as > isotropy as we commonly imagine - in that it is not a nice smooth > balloon shaped surface to bounce a signal off of. Instead, there are > varying degrees of irregularity, not unlike a sandy desert where the > wind moves the landscape around and creates moving peaks and valleys. > So imagine the ionosphere in this condition when a signal from one > direction has a nice reflection down to the receiver, but in the other > direction, it is reflected at a different angle and lands somewhere else. > > Jim, KR9U > There is no possible combination of refractions or reflections that is not reciprocal in both directions. If there is a mechanism at work, it is at an entirely different level than simple multiple reflections. After 50 years on 160, I'm still unsure if one way propagation exists. All of the "one way" I have seen and taken the time to look at involves noise levels, QRM, or just the capability of the stations. For example, prior to sunset here my local noise is very low. Even on a quiet winter night in a quiet direction, noise floor increases 10-15 dB as it gets darker and conditions improve. I can hear Europeans that I have no hope of working (on 40 meters this happens all day long). Their noise is high (even in a quiet location) because it is dark. As it gets darker their signals come up, and so does my noise and QRM, but eventually they hear me. The opposite occurs at sunrise. There is the same noise floor drop after daylight. This means I can hear JA's working west coast stations long after they stop being able to hear me. Local storms and local QRM, and the direction of that stuff, is also is a huge factor in reciprocity. Sorting it all out is very complicated, and involves far more than observing "sometimes people at one end don't answer". Sorting it out would involve and **require** calibrated observations of absolute signal levels and noise levels at both ends. I think this is why one way prop is, at best, arguable. 73 Tom ___ Topband reflector - topband@contesting.com ___ Topband reflector - topband@contesting.com
Topband: one- way propagation
Interesting theories and observations regarding one way propagation..My take is that most of the seemingly one way prop is more dependent on operator skill and the local qrn at one end of the circuit..With the current conditions this past 12 months most usually strong signals on the band are often attenuated due to less than a reliable path..I hear many signals that may be only S1-3and few hear a station calling them..These conditions may give the impression of "one way" prop but it is more likely due to qrn conditions at the listening end...I am looking at this from the VK cross the Equator Summer/Winter differences which have a big influence on making a contact..My observations over 35 years show that there is propagation most of the time all year if stations take the time and patience to listen for DX.. Bob..VK3ZL.. ___ Topband reflector - topband@contesting.com
Re: Topband: one-way propagation
Yes, a good point that I neglected. This entirely circumvents my yammerings about reciprocity. Reciprocity is a characteristic of a single pair of ports in a network. Introducing separate receive antennas can surely cause a one way effect. Consider what happens when I hook up a dummy load as a Rx antenna ... 73 and thanks for listening, Carl WS7L I've often thought that some "one-way propagation" is simply due to the > differences in antennas. For example, two stations with the same power, > ambient noise level, etc. are receiving on Beverages pointed at each other, > but their TX antennas have different takeoff angles and/or patterns. ___ Topband reflector - topband@contesting.com
Re: Topband: one-way propagation
Jim Not always, polarization plays a lot on 160m, in special W-E E-W. Sometimes a signal from Africa dive on the QSB and disappear from the Vertical WF and switching to the horizontal WF the signal is peaking, other times I only can hear the DX signal horizontal. I don't call this unidirectional because I use a vertical TX all the time and the DX hears me well even the signal is arriving horizontal. Regards Jose Carlos N4IS -Original Message- From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of James Wolf Sent: Tuesday, December 04, 2012 3:41 PM To: 'Tom W8JI'; topband@contesting.com Subject: Re: Topband: one-way propagation Tom, It is a known that the ionosphere is not a perfect sphere. It is always moving and it is lumpy and tilted. Together these occurrences can cause focusing and defocusing of the wave due to deformities especially if they are concave or convex. One-way-propagation can reveal itself as a deep and/or prolonged fade on only one end of the link because of the aforementioned reasons.Of course fades can be caused by other reasons, such as multiple paths, etc. Jim, KR9U -Original Message- From: Tom W8JI [mailto:w...@w8ji.com] Sent: Tuesday, December 04, 2012 6:45 AM To: jbw...@comcast.net; topband@contesting.com Subject: Re: Topband: one-way propagation > To expand a little on Carl's explanation, the ionosphere is not as > isotropy as we commonly imagine - in that it is not a nice smooth > balloon shaped surface to bounce a signal off of. Instead, there are > varying degrees of irregularity, not unlike a sandy desert where the > wind moves the landscape around and creates moving peaks and valleys. > So imagine the ionosphere in this condition when a signal from one > direction has a nice reflection down to the receiver, but in the other > direction, it is reflected at a different angle and lands somewhere else. > > Jim, KR9U > There is no possible combination of refractions or reflections that is not reciprocal in both directions. If there is a mechanism at work, it is at an entirely different level than simple multiple reflections. After 50 years on 160, I'm still unsure if one way propagation exists. All of the "one way" I have seen and taken the time to look at involves noise levels, QRM, or just the capability of the stations. For example, prior to sunset here my local noise is very low. Even on a quiet winter night in a quiet direction, noise floor increases 10-15 dB as it gets darker and conditions improve. I can hear Europeans that I have no hope of working (on 40 meters this happens all day long). Their noise is high (even in a quiet location) because it is dark. As it gets darker their signals come up, and so does my noise and QRM, but eventually they hear me. The opposite occurs at sunrise. There is the same noise floor drop after daylight. This means I can hear JA's working west coast stations long after they stop being able to hear me. Local storms and local QRM, and the direction of that stuff, is also is a huge factor in reciprocity. Sorting it all out is very complicated, and involves far more than observing "sometimes people at one end don't answer". Sorting it out would involve and **require** calibrated observations of absolute signal levels and noise levels at both ends. I think this is why one way prop is, at best, arguable. 73 Tom ___ Topband reflector - topband@contesting.com ___ Topband reflector - topband@contesting.com
Re: Topband: one-way propagation
It is a known that the ionosphere is not a perfect sphere. It is always moving and it is lumpy and tilted. Together these occurrences can cause focusing and defocusing of the wave due to deformities especially if they are concave or convex. One-way-propagation can reveal itself as a deep and/or prolonged fade on only one end of the link because of the aforementioned reasons.Of course fades can be caused by other reasons, such as multiple paths, etc. I can't recall anyone who has made a study of this citing that as a reason for non-reciprocity, and Carl's recent post about a broadcast study said the effect someone reported seeing was only on a west-east path and no one knew why. The reasons theorists have cited have only to due with gyrorotation. I'm not saying you are wrong, but what have they missed to not bring the issues you highlight up? In all of the conditions you mention, what specific mechanism causes a path to be non-reciprocal at any instant of time? I know why things like lossy networks can be non-reciprocal in impedance, but what is the mechanism at work? 73 Tom ___ Topband reflector - topband@contesting.com
Re: Topband: one-way propagation
I've often thought that some "one-way propagation" is simply due to the differences in antennas. For example, two stations with the same power, ambient noise level, etc. are receiving on Beverages pointed at each other, but their TX antennas have different takeoff angles and/or patterns. For example. station A with an NVIS antenna (like a low horizontal loop) might hear station B who is transmitting on a vertical, but maybe not vice versa. 73, Mike www.w0btu.com ___ Topband reflector - topband@contesting.com
Re: Topband: one-way propagation
I'm weighing in with Tom here. The reciprocity theorem in electromagnetism is well known, and it shows that no amount of focusing, defocusing, scattering, refraction, or reflection will by themselves cause one way propagation. If you take away the earth's magnetic field and its attendant Faraday rotation, I do not see any other reason for one-way propagation if noise levels at both ends of the path are equal. See http://en.wikipedia.org/wiki/Reciprocity_(electromagnetism) and http://en.wikipedia.org/wiki/Faraday_effect#Faraday_rotation_in_the_ionosphere . 73, Carl WS7L Tom, > > It is a known that the ionosphere is not a perfect sphere. It is always > moving and it is lumpy and tilted. Together these occurrences can cause > focusing and defocusing of the wave due to deformities especially if they > are concave or convex. One-way-propagation can reveal itself as a deep > and/or prolonged fade on only one end of the link because of the > aforementioned reasons.Of course fades can be caused by other reasons, > such as multiple paths, etc. > ___ Topband reflector - topband@contesting.com
Re: Topband: one-way propagation
Tom, It is a known that the ionosphere is not a perfect sphere. It is always moving and it is lumpy and tilted. Together these occurrences can cause focusing and defocusing of the wave due to deformities especially if they are concave or convex. One-way-propagation can reveal itself as a deep and/or prolonged fade on only one end of the link because of the aforementioned reasons.Of course fades can be caused by other reasons, such as multiple paths, etc. Jim, KR9U -Original Message- From: Tom W8JI [mailto:w...@w8ji.com] Sent: Tuesday, December 04, 2012 6:45 AM To: jbw...@comcast.net; topband@contesting.com Subject: Re: Topband: one-way propagation > To expand a little on Carl's explanation, the ionosphere is not as > isotropy as we commonly imagine - in that it is not a nice smooth > balloon shaped surface to bounce a signal off of. Instead, there are > varying degrees of irregularity, not unlike a sandy desert where the > wind moves the landscape around and creates moving peaks and valleys. > So imagine the ionosphere in this condition when a signal from one > direction has a nice reflection down to the receiver, but in the other > direction, it is reflected at a different angle and lands somewhere else. > > Jim, KR9U > There is no possible combination of refractions or reflections that is not reciprocal in both directions. If there is a mechanism at work, it is at an entirely different level than simple multiple reflections. After 50 years on 160, I'm still unsure if one way propagation exists. All of the "one way" I have seen and taken the time to look at involves noise levels, QRM, or just the capability of the stations. For example, prior to sunset here my local noise is very low. Even on a quiet winter night in a quiet direction, noise floor increases 10-15 dB as it gets darker and conditions improve. I can hear Europeans that I have no hope of working (on 40 meters this happens all day long). Their noise is high (even in a quiet location) because it is dark. As it gets darker their signals come up, and so does my noise and QRM, but eventually they hear me. The opposite occurs at sunrise. There is the same noise floor drop after daylight. This means I can hear JA's working west coast stations long after they stop being able to hear me. Local storms and local QRM, and the direction of that stuff, is also is a huge factor in reciprocity. Sorting it all out is very complicated, and involves far more than observing "sometimes people at one end don't answer". Sorting it out would involve and **require** calibrated observations of absolute signal levels and noise levels at both ends. I think this is why one way prop is, at best, arguable. 73 Tom ___ Topband reflector - topband@contesting.com
Re: Topband: one-way propagation
To expand a little on Carl's explanation, the ionosphere is not as isotropy as we commonly imagine - in that it is not a nice smooth balloon shaped surface to bounce a signal off of. Instead, there are varying degrees of irregularity, not unlike a sandy desert where the wind moves the landscape around and creates moving peaks and valleys. So imagine the ionosphere in this condition when a signal from one direction has a nice reflection down to the receiver, but in the other direction, it is reflected at a different angle and lands somewhere else. Jim, KR9U There is no possible combination of refractions or reflections that is not reciprocal in both directions. If there is a mechanism at work, it is at an entirely different level than simple multiple reflections. After 50 years on 160, I'm still unsure if one way propagation exists. All of the "one way" I have seen and taken the time to look at involves noise levels, QRM, or just the capability of the stations. For example, prior to sunset here my local noise is very low. Even on a quiet winter night in a quiet direction, noise floor increases 10-15 dB as it gets darker and conditions improve. I can hear Europeans that I have no hope of working (on 40 meters this happens all day long). Their noise is high (even in a quiet location) because it is dark. As it gets darker their signals come up, and so does my noise and QRM, but eventually they hear me. The opposite occurs at sunrise. There is the same noise floor drop after daylight. This means I can hear JA's working west coast stations long after they stop being able to hear me. Local storms and local QRM, and the direction of that stuff, is also is a huge factor in reciprocity. Sorting it all out is very complicated, and involves far more than observing "sometimes people at one end don't answer". Sorting it out would involve and **require** calibrated observations of absolute signal levels and noise levels at both ends. I think this is why one way prop is, at best, arguable. 73 Tom ___ Topband reflector - topband@contesting.com
Re: Topband: one-way propagation
I worked about 40 stations during ARRL 160m by S&P. Best signals strength occured between 21:00 and 22:00 UTC both days with VY2ZM peaking S9+20db. That is around your sunset at the east coast. Band sharing with commercial stations is not existing on 160m and 80m and BC station interference (bad tx) happens rarely on 40m. 73 Peter, DJ7WW -Original Message- From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of ZR Sent: Montag, 3. Dezember 2012 20:05 To: k...@frontier.com; topband@contesting.com Subject: Re: Topband: one-way propagation Having operated in Western and Central Europe a few times over the years on 160-40M from average to better stations Ive observed something else. With the typical 5-7 hour time difference the East Coast hears EU well before sunset in the winter and its hard to impossible to attract a QSO. This is the prime evening time in EU where activity is highest adding to the across the band din making weak signals poor copy. Also there is band sharing with commercial and other stations that drops down considerably as the evening progresses. Some of those signals are wide with TX generated noise. As it approaches EU bed time the consumer noise generators are shut off, more hams are in bed and the bands "seem" to open to NA. A good part of EU is also under the auroral curtain at times which adds to the band noise and signal attenuation. Whatever real or imagined propagation anomalies exist just add to the problem. The only cures I know of are running a remote TX a lot closer to EU; or a tube with handles and a 10dB+ boost over 1500W such as he who is often complaining about others comments on here. Carl KM1H - Original Message - From: To: Sent: Monday, December 03, 2012 1:09 PM Subject: Topband: one-way propagation > Jim K9YC asked about other possible mechanisms besides atmospheric noise > to account for one-way propagation on 160-Meters. For the record, I also > believe atmospheric noise (and even man-made noise as experienced by the > PT0S ops) is a big player in these observations. By the way, I also would > like to extend a big THANK YOU to the PT0S ops, especially for their > topband effort. > One-way proapgation was an interesting topic in the AM broadcast industry > in the 1970s (I do not know if it still is). The issue was tied to > allocation of frequencies and the difference in loss depending on whether > it was an east-to-west path or a west-to-east path. John C. Wang of the > FCC measured signal strengths of 18 MF broadcasting stations (540 - 1630 > KHz) at 4 receiving sites throughout the continental US to compare the > measurements to the CCIR model. > Subsequent analysis of this data by Douglass D. Crombie of the Institute > for Telecommunication Sciences in Boulder found that for paths between 200 > km and 3000 km, the east-to-west path loss is some 9 dB greater than in > the west-to-east direction. Further analysis shows this is highest for > frequencies above 830 KHz. The data did not show any such difference on > north-to-south paths and south-to-north paths. > The second-to-last sentence in the previous paragraph suggests that the > ionosphere, being immersed in the Earth's magnetic field, is anisotropic - > in other words, the ionosphere looks different for RF going east-to-west > versus west-to-east. But if you run ray traces with Proplab Pro (it > includes the effects of the magnetic field and electron-neutral > collisions) for both directions, you will see no significant difference - > at least I have not for my runs). We have to watch it here, though - the > model of the ionosphere in Proplab Pro is a monthly median model (as it is > in all of our propagation prediction programs) - so it does not capture > the day-to-day variability, which may be involved in these observations. > So I believe there is a possibility that there are other mechanisms at > play to give us one-way propagation. Unfortunately, as far as I am aware, > we do not understand them. > Carl K9LA > ___ > Topband reflector - topband@contesting.com > > - > No virus found in this message. > Checked by AVG - www.avg.com > Version: 10.0.1427 / Virus Database: 2634/5434 - Release Date: 12/03/12 > ___ Topband reflector - topband@contesting.com ___ Topband reflector - topband@contesting.com
Re: Topband: one-way propagation
Having operated in Western and Central Europe a few times over the years on 160-40M from average to better stations Ive observed something else. With the typical 5-7 hour time difference the East Coast hears EU well before sunset in the winter and its hard to impossible to attract a QSO. This is the prime evening time in EU where activity is highest adding to the across the band din making weak signals poor copy. Also there is band sharing with commercial and other stations that drops down considerably as the evening progresses. Some of those signals are wide with TX generated noise. As it approaches EU bed time the consumer noise generators are shut off, more hams are in bed and the bands "seem" to open to NA. A good part of EU is also under the auroral curtain at times which adds to the band noise and signal attenuation. Whatever real or imagined propagation anomalies exist just add to the problem. The only cures I know of are running a remote TX a lot closer to EU; or a tube with handles and a 10dB+ boost over 1500W such as he who is often complaining about others comments on here. Carl KM1H - Original Message - From: To: Sent: Monday, December 03, 2012 1:09 PM Subject: Topband: one-way propagation Jim K9YC asked about other possible mechanisms besides atmospheric noise to account for one-way propagation on 160-Meters. For the record, I also believe atmospheric noise (and even man-made noise as experienced by the PT0S ops) is a big player in these observations. By the way, I also would like to extend a big THANK YOU to the PT0S ops, especially for their topband effort. One-way proapgation was an interesting topic in the AM broadcast industry in the 1970s (I do not know if it still is). The issue was tied to allocation of frequencies and the difference in loss depending on whether it was an east-to-west path or a west-to-east path. John C. Wang of the FCC measured signal strengths of 18 MF broadcasting stations (540 – 1630 KHz) at 4 receiving sites throughout the continental US to compare the measurements to the CCIR model. Subsequent analysis of this data by Douglass D. Crombie of the Institute for Telecommunication Sciences in Boulder found that for paths between 200 km and 3000 km, the east-to-west path loss is some 9 dB greater than in the west-to-east direction. Further analysis shows this is highest for frequencies above 830 KHz. The data did not show any such difference on north-to-south paths and south-to-north paths. The second-to-last sentence in the previous paragraph suggests that the ionosphere, being immersed in the Earth's magnetic field, is anisotropic – in other words, the ionosphere looks different for RF going east-to-west versus west-to-east. But if you run ray traces with Proplab Pro (it includes the effects of the magnetic field and electron-neutral collisions) for both directions, you will see no significant difference – at least I have not for my runs). We have to watch it here, though – the model of the ionosphere in Proplab Pro is a monthly median model (as it is in all of our propagation prediction programs) – so it does not capture the day-to-day variability, which may be involved in these observations. So I believe there is a possibility that there are other mechanisms at play to give us one-way propagation. Unfortunately, as far as I am aware, we do not understand them. Carl K9LA ___ Topband reflector - topband@contesting.com - No virus found in this message. Checked by AVG - www.avg.com Version: 10.0.1427 / Virus Database: 2634/5434 - Release Date: 12/03/12 ___ Topband reflector - topband@contesting.com
Re: Topband: one-way propagation
To expand a little on Carl's explanation, the ionosphere is not as isotropy as we commonly imagine - in that it is not a nice smooth balloon shaped surface to bounce a signal off of. Instead, there are varying degrees of irregularity, not unlike a sandy desert where the wind moves the landscape around and creates moving peaks and valleys. So imagine the ionosphere in this condition when a signal from one direction has a nice reflection down to the receiver, but in the other direction, it is reflected at a different angle and lands somewhere else. Jim, KR9U -Original Message- From: Topband [mailto:topband-boun...@contesting.com] On Behalf Of k...@frontier.com Sent: Monday, December 03, 2012 1:10 PM To: topband@contesting.com Subject: Topband: one-way propagation Jim K9YC asked about other possible mechanisms besides atmospheric noise to account for one-way propagation on 160-Meters. For the record, I also believe atmospheric noise (and even man-made noise as experienced by the PT0S ops) is a big player in these observations. By the way, I also would like to extend a big THANK YOU to the PT0S ops, especially for their topband effort. One-way proapgation was an interesting topic in the AM broadcast industry in the 1970s (I do not know if it still is). The issue was tied to allocation of frequencies and the difference in loss depending on whether it was an east-to-west path or a west-to-east path. John C. Wang of the FCC measured signal strengths of 18 MF broadcasting stations (540 – 1630 KHz) at 4 receiving sites throughout the continental US to compare the measurements to the CCIR model. Subsequent analysis of this data by Douglass D. Crombie of the Institute for Telecommunication Sciences in Boulder found that for paths between 200 km and 3000 km, the east-to-west path loss is some 9 dB greater than in the west-to-east direction. Further analysis shows this is highest for frequencies above 830 KHz. The data did not show any such difference on north-to-south paths and south-to-north paths. The second-to-last sentence in the previous paragraph suggests that the ionosphere, being immersed in the Earth's magnetic field, is anisotropic – in other words, the ionosphere looks different for RF going east-to-west versus west-to-east. But if you run ray traces with Proplab Pro (it includes the effects of the magnetic field and electron-neutral collisions) for both directions, you will see no significant difference – at least I have not for my runs). We have to watch it here, though – the model of the ionosphere in Proplab Pro is a monthly median model (as it is in all of our propagation prediction programs) – so it does not capture the day-to-day variability, which may be involved in these observations. So I believe there is a possibility that there are other mechanisms at play to give us one-way propagation. Unfortunately, as far as I am aware, we do not understand them. Carl K9LA ___ Topband reflector - topband@contesting.com ___ Topband reflector - topband@contesting.com
Re: Topband: one-way propagation
On 12/3/2012 10:09 AM, k...@frontier.com wrote: So I believe there is a possibility that there are other mechanisms at play to give us one-way propagation. Unfortunately, as far as I am aware, we do not understand them. Thanks for the great response, Carl. 73, Jim K9YC ___ Topband reflector - topband@contesting.com
Topband: one-way propagation
Jim K9YC asked about other possible mechanisms besides atmospheric noise to account for one-way propagation on 160-Meters. For the record, I also believe atmospheric noise (and even man-made noise as experienced by the PT0S ops) is a big player in these observations. By the way, I also would like to extend a big THANK YOU to the PT0S ops, especially for their topband effort. One-way proapgation was an interesting topic in the AM broadcast industry in the 1970s (I do not know if it still is). The issue was tied to allocation of frequencies and the difference in loss depending on whether it was an east-to-west path or a west-to-east path. John C. Wang of the FCC measured signal strengths of 18 MF broadcasting stations (540 – 1630 KHz) at 4 receiving sites throughout the continental US to compare the measurements to the CCIR model. Subsequent analysis of this data by Douglass D. Crombie of the Institute for Telecommunication Sciences in Boulder found that for paths between 200 km and 3000 km, the east-to-west path loss is some 9 dB greater than in the west-to-east direction. Further analysis shows this is highest for frequencies above 830 KHz. The data did not show any such difference on north-to-south paths and south-to-north paths. The second-to-last sentence in the previous paragraph suggests that the ionosphere, being immersed in the Earth's magnetic field, is anisotropic – in other words, the ionosphere looks different for RF going east-to-west versus west-to-east. But if you run ray traces with Proplab Pro (it includes the effects of the magnetic field and electron-neutral collisions) for both directions, you will see no significant difference – at least I have not for my runs). We have to watch it here, though – the model of the ionosphere in Proplab Pro is a monthly median model (as it is in all of our propagation prediction programs) – so it does not capture the day-to-day variability, which may be involved in these observations. So I believe there is a possibility that there are other mechanisms at play to give us one-way propagation. Unfortunately, as far as I am aware, we do not understand them. Carl K9LA ___ Topband reflector - topband@contesting.com
