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PVRC Webinar - 20Oct09 - K9LA 1 Propagation Prediction Programs: Their Development and Use Carl Luetzelschwab K9LA

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Presentation on theme: "PVRC Webinar - 20Oct09 - K9LA 1 Propagation Prediction Programs: Their Development and Use Carl Luetzelschwab K9LA"— Presentation transcript:

1 PVRC Webinar - 20Oct09 - K9LA 1 Propagation Prediction Programs: Their Development and Use Carl Luetzelschwab K9LA

2 PVRC Webinar - 20Oct09 - K9LA2 What Were Going to Cover How the ionosphere forms How the ionosphere forms Measuring the ionosphere Measuring the ionosphere Solar-ionosphere correlation Solar-ionosphere correlation Variability of the ionosphere Variability of the ionosphere Sample prediction Sample prediction Understanding prediction outputs Understanding prediction outputs This presentation will be on the PVRC website visit click on the PVRC Webinars link at the top

3 PVRC Webinar - 20Oct09 - K9LA3 How the Ionosphere Forms

4 PVRC Webinar - 20Oct09 - K9LA4 The Atmosphere Composition of the atmosphere Composition of the atmosphere –78.1% nitrogen, 20.9% oxygen, 1% other gases Species that are important in the ionosphere Species that are important in the ionosphere Maximum wavelength is longest wavelength of radiation that can cause ionization Maximum wavelength is longest wavelength of radiation that can cause ionization –Related to ionization potential through Plancks Constant 10.7 cm = 107,000,000 nm 10.7 cm = 107,000,000 nm –10.7 cm solar flux doesnt ionize anything –It is a proxy (substitute) for the true ionizing radiation The sunspot number is also a proxy The sunspot number is also a proxy Visible light = 400 to 700 nm Visible light = 400 to 700 nm

5 PVRC Webinar - 20Oct09 - K9LA5 True Ionizing Radiation As radiation progresses down through the atmosphere, it is absorbed by the aforementioned species in the process of ionization As radiation progresses down through the atmosphere, it is absorbed by the aforementioned species in the process of ionization –Energy reduced as it proceeds lower –Need higher energy radiation (shorter wavelengths) to get lower True ionizing radiation can be summarized as follows True ionizing radiation can be summarized as follows –.1 to 1 nm and nm for the D region nm (Lyman- hydrogen spectral line) is the result of a minimum in the absorption coefficient of O 2 and N nm (Lyman- hydrogen spectral line) is the result of a minimum in the absorption coefficient of O 2 and N 2 –It goes through the higher altitudes easily, and ionizes NO at lower altitudes to give us daytime absorption –1 to 10 nm for the E region –10 to 100 nm for the F 2 region Sunspots and 10.7 cm solar flux are proxies for the true ionizing radiation

6 PVRC Webinar - 20Oct09 - K9LA6 Measuring the Ionosphere

7 PVRC Webinar - 20Oct09 - K9LA7 Introduction to Ionosondes To make predictions, you need a model of the ionosphere To make predictions, you need a model of the ionosphere Model developed from ionosonde data Model developed from ionosonde data Most ionosondes are equivalent to swept-frequency radars that look straight up Most ionosondes are equivalent to swept-frequency radars that look straight up –Co-located transmitter and receiver –Also referred to as vertical ionosondes or vertically-incident ionosondes There are also oblique ionosondes There are also oblique ionosondes –Transmitter and receiver separated –Evaluate a specific path

8 PVRC Webinar - 20Oct09 - K9LA8 What Does an Ionosonde Measure? It measures the time for a wave to go up, to be turned around, and to come back down It measures the time for a wave to go up, to be turned around, and to come back down Thus the true measurement is time, not height Thus the true measurement is time, not height This translates to virtual height assuming the speed of light and mirror-like reflection This translates to virtual height assuming the speed of light and mirror-like reflection The real wave does not get as high as the virtual height The real wave does not get as high as the virtual height An ionosonde measures time of flight, not altitude, at each frequency

9 PVRC Webinar - 20Oct09 - K9LA9 Sample Ionogram Red is ordinary wave, green is extraordinary wave Red is ordinary wave, green is extraordinary wave Critical frequencies are highest frequencies that are returned to Earth from each region at vertical incidence Critical frequencies are highest frequencies that are returned to Earth from each region at vertical incidence Electron density profile is derived from the ordinary wave data (along with a couple assumptions about region thickness) Electron density profile is derived from the ordinary wave data (along with a couple assumptions about region thickness) –Electron density anywhere in the ionosphere is equivalent to a plasma frequency through the equation f p (Hz) = 9 x N 1/2 with N in electrons/m 3 E region and F 2 region have maximums in electron density E region and F 2 region have maximums in electron density F 1 region is inflection point in electron density F 1 region is inflection point in electron density D region not measured D region not measured Nighttime data only consists of F 2 region and sporadic E due to TX ERP and RX sensitivity (limit is ~1.8 MHz) Nighttime data only consists of F 2 region and sporadic E due to TX ERP and RX sensitivity (limit is ~1.8 MHz) foE foF 1 foF 2 fxF 2 electron density profile daytime data Note that we dont see layers with gaps in between

10 PVRC Webinar - 20Oct09 - K9LA10 Characterizing the Ionosphere Ionosphere is characterized in terms of critical frequencies (foE, foF 1, foF 2 ) and heights of maximum electron densities (hmE, hmF 2 ) Ionosphere is characterized in terms of critical frequencies (foE, foF 1, foF 2 ) and heights of maximum electron densities (hmE, hmF 2 ) –Easier to use than electron densities Allows us to calculate propagation over oblique paths Allows us to calculate propagation over oblique paths –MUF(2000)E = foE x M-Factor for E region –MUF(3000)F 2 = foF 2 x M-Factor for F 2 region Rule of thumb: E region M-factor ~ 5, F 2 region M-factor ~ 3 Rule of thumb: E region M-factor ~ 5, F 2 region M-factor ~ 3 for more on the M-Factor, visit

11 PVRC Webinar - 20Oct09 - K9LA11 Solar – Ionosphere Correlation

12 PVRC Webinar - 20Oct09 - K9LA12 Whats the Correlation? Many years of solar data and worldwide ionosonde data collected Many years of solar data and worldwide ionosonde data collected The task of the propagation prediction developers was to determine the correlation between solar data and ionosonde data The task of the propagation prediction developers was to determine the correlation between solar data and ionosonde data It would have been nice to find a correlation between what the ionosphere was doing on a given day and what the Sun was doing on the same day It would have been nice to find a correlation between what the ionosphere was doing on a given day and what the Sun was doing on the same day solar data ionosonde data ???

13 PVRC Webinar - 20Oct09 - K9LA13 But That Didnt Happen August 2009 August 2009 August 2009 –Zero sunspots –Constant 10.7 cm flux No correlation between daily values No correlation between daily values –Low of 11.6 MHz on August 14 –High of 21.5 MHz on August 16 Indicates there are other factors in determining the ultimate ionization Indicates there are other factors in determining the ultimate ionization Comment about CQ WW Phone 2007, 2008 Comment about CQ WW Phone 2007, 2008

14 PVRC Webinar - 20Oct09 - K9LA14 So Now What? Not too good - the developers were forced to come up with a statistical model over a months time frame Good – smoothed solar flux (or smoothed sunspot number) and monthly median parameters R 2 =.0615 R 2 =.8637

15 PVRC Webinar - 20Oct09 - K9LA15 How Do You Determine the Monthly Median? raw data put foF 2 in ascending order median implies 50% half of the values below median half of the values above median median Variation about the median follows a Chi- squared distribution, thus probabilities can be calculated (more on this later)

16 PVRC Webinar - 20Oct09 - K9LA16 Correlation Between SF and SSN Smoothed solar flux φ 12 = R (R 12 ) 2 Smoothed sunspot number R 12 = ( φ 12 ) 1/2 – Using these equations to convert between daily solar flux and daily sunspot number results in a lot of uncertainty

17 PVRC Webinar - 20Oct09 - K9LA17 Variability of the Ionosphere

18 PVRC Webinar - 20Oct09 - K9LA18 What Causes this Variability? Rishbeth and Mendillo, Journal of Atmospheric and Solar-Terrestrial Physics, Vol 63, 2001, pp Rishbeth and Mendillo, Journal of Atmospheric and Solar-Terrestrial Physics, Vol 63, 2001, pp –Looked at 34 years of foF 2 data –Used data from 13 ionosondes –Day-to-day daytime variability (std dev/monthly mean) = 20% Solar ionizing radiation contributed about 3% Solar ionizing radiation contributed about 3% Solar wind, geomagnetic field activity, electrodynamics about 13% Solar wind, geomagnetic field activity, electrodynamics about 13% Neutral atmosphere about 15% Neutral atmosphere about 15% [20%] 2 = [3%] 2 + [13%] 2 + [15%] 2 [20%] 2 = [3%] 2 + [13%] 2 + [15%] 2

19 PVRC Webinar - 20Oct09 - K9LA19 Is the Ionosphere In Step? 3000 km MUF over Millstone Hill and Wallops Island 3000 km MUF over Millstone Hill and Wallops Island Separated by 653 km = 408 miles Separated by 653 km = 408 miles Several periods show up when the ionosphere was going opposite ways Several periods show up when the ionosphere was going opposite ways Worldwide ionosphere not necessarily in step Worldwide ionosphere not necessarily in step

20 PVRC Webinar - 20Oct09 - K9LA20 We Dont Have Daily Predictions Day-to-day variability just too great Day-to-day variability just too great We have a good understanding of the solar influence We have a good understanding of the solar influence Were beginning to better understand the geomagnetic field influence Were beginning to better understand the geomagnetic field influence –Its a bit more than just low K = good and high K = bad We are lacking a good understanding of how events in the lower atmosphere couple up to the ionosphere We are lacking a good understanding of how events in the lower atmosphere couple up to the ionosphere –This is a major reason why prediction programs dont cover 160m (along with the effect of the Earths magnetic field through the electron-gyro frequency) 160m RF doesnt get as high into the ionosphere as the higher frequencies 160m RF doesnt get as high into the ionosphere as the higher frequencies –Doesnt help that ionosondes dont measure the lower ionosphere – especially at night when we chase DX on the low bands

21 PVRC Webinar - 20Oct09 - K9LA21 Summary So Far Our propagation prediction programs are based on the correlation between a smoothed solar index and monthly median ionospheric parameters Our propagation prediction programs are based on the correlation between a smoothed solar index and monthly median ionospheric parameters –Monthly median parameters can be represented in different ways Database of numerical coefficients Database of numerical coefficients Equations Equations International Reference Ionosphere International Reference Ionosphere Our predictions programs are pretty accurate when the geomagnetic field is quiet Our predictions programs are pretty accurate when the geomagnetic field is quiet Real-time MUF maps seen on the web are kind of a misnomer Real-time MUF maps seen on the web are kind of a misnomer –If they use a smoothed solar index, then theyre monthly median MUFs –If they use todays solar flux or todays sunspot number (maybe even with todays A index), I dont know what they are! Now its time to run a sample prediction Now its time to run a sample prediction We dont have daily predictions

22 PVRC Webinar - 20Oct09 - K9LA22 Sample Prediction

23 PVRC Webinar - 20Oct09 - K9LA23 K9LA to ZF Latitudes / longitudes Latitudes / longitudes –K9LA = 41.0N / 85.0W –ZF = 19.5N / 80.5W October 2004 October 2004 –Smoothed sunspot number ~ 35 (smoothed solar flux ~ 91) Are we ever going to see that again? Are we ever going to see that again? Antennas Antennas –Small Yagis on both ends = 12 dBi gain Power Power –1000 Watts on both ends Bands and Path Bands and Path –20m, 17m, 15m on the Short Path Well use VOACAP Well use VOACAP –When you download VOACAP (comes with ICEPAC and REC533), read the Technical Manual and Users Manual – lots of good info

24 PVRC Webinar - 20Oct09 - K9LA24 VOACAP Input Parameters Method Method –Controls the type of program analysis and the predictions performed –Recommend using Method 30 (Short\Long Smoothing) most of the time –Methods 1 and 25 helpful for analysis of the ionosphere Coefficients Coefficients –CCIR (International Radio Consultative Committee) Shortcomings over oceans and in southern hemisphere Shortcomings over oceans and in southern hemisphere Most validated Most validated –URSI (International Union of Radio Scientists) Rush, et al, used aeronomic theory to fill in the gaps Rush, et al, used aeronomic theory to fill in the gaps Groups Groups –Month.Day means centered on the middle of October means centered on the middle of October means centered on the 5 th of October means centered on the 5 th of October –Defaults to URSI coefficients

25 PVRC Webinar - 20Oct09 - K9LA25 VOACAP Input Parameters System System –Noisedefault is residential –Min Angle1 degree (emulate obstructions to radiation) –Req Reldefault is 90% –Req SNR48 dB in 1 Hz (13 dB in 3 KHz: 90% intelligibility) –Multi Toldefault is 3 dB –Multi Deldefault is.1 milliseconds Fprob Fprob –Multipliers to increase or reduce MUF Default is 1.00 for foE, foF1, foF2 and 0.00 for foEs Default is 1.00 for foE, foF1, foF2 and 0.00 for foEs For more details on setting up and running VOACAP, either visit by Jari OH6BG (lots of good info) or

26 PVRC Webinar - 20Oct09 - K9LA26 Prediction Printout FREQ 1F2 1F2 1F2 1F MODE TANGLE DELAY V HITE MUFday LOSS DBU S DBW N DBW SNR RPWRG REL MPROB S PRB SIG LW SIG UP SNR LW SNR UP TGAIN RGAIN SNRxx

27 PVRC Webinar - 20Oct09 - K9LA27 Understanding Prediction Outputs

28 PVRC Webinar - 20Oct09 - K9LA28 Focus on 15m at 1300 UTC FREQ 1F2 1F2 1F2 1F MODE TANGLE DELAY V HITE MUFday LOSS DBU S DBW N DBW SNR RPWRG REL MPROB S PRB SIG LW SIG UP SNR LW SNR UP TGAIN RGAIN SNRxx monthly median MUF time MUFday for 15m signal power

29 PVRC Webinar - 20Oct09 - K9LA29 15m Openings at 1300 UTC 20.9 MHz (monthly median) 20.9 MHz (monthly median) –Enough ionization on half the days of the month 21.2 MHz 21.2 MHz –Enough ionization on.46 x 31 = 14 days of the month 14 MHz and below 14 MHz and below –Enough ionization every day of the month 24.9 MHz 24.9 MHz –Enough ionization on 1 day of the month 28.3 MHz 28.3 MHz –Not enough ionization on any day We cant predict which days are the good days

30 PVRC Webinar - 20Oct09 - K9LA30 15m Signal Power -94 dBW (monthly median) = -64 dBm -94 dBW (monthly median) = -64 dBm Assume Assume –S9 = -73 dBm (50 microvolts into 50Ω) –one S-unit = 5 dB typical of receivers Ive measured typical of receivers Ive measured –except below S3 or so its only a couple dB per S-unit -64 dBm = 10 dB over S9 -64 dBm = 10 dB over S9 Variability about the monthly median from ionospheric texts (for example, Supplement to Report 252-2, CCIR, 1978) Variability about the monthly median from ionospheric texts (for example, Supplement to Report 252-2, CCIR, 1978) Signal power could be from one S-unit higher to two S-units lower on any given day on this path Signal power could be from one S-unit higher to two S-units lower on any given day on this path –S9 to 15 over 9 for this path Rule of thumb – actual signal power for any path could be from a couple S-units higher to several S-units lower than median on any given day Rule of thumb – actual signal power for any path could be from a couple S-units higher to several S-units lower than median on any given day Dont make assumptions about your S-meter – measure it S dBm S9 -73 dBm S8 -78 dBm S7 -83 dBm S6 -88 dBm S5 -93 dBm S4 -98 dBm S dBm S dBm S dBm

31 PVRC Webinar - 20Oct09 - K9LA31 VOACAP vs W6ELProp

32 PVRC Webinar - 20Oct09 - K9LA32 Whats Different with W6ELProp? Underlying concept is still the correlation between a smoothed solar parameter and monthly median ionospheric parameters Underlying concept is still the correlation between a smoothed solar parameter and monthly median ionospheric parameters For foF 2, W6ELProp uses equations developed by Raymond Fricker of the BBC For foF 2, W6ELProp uses equations developed by Raymond Fricker of the BBC –VOACAP uses database of numerical coefficients to describe worldwide ionosphere –Another option is IRI (PropLab Pro) W6ELProp rigorously calculates signal strength using CCIR methods W6ELProp rigorously calculates signal strength using CCIR methods –VOACAP calibrated against actual measurements For more details on setting up and running W6ELProp, visit

33 PVRC Webinar - 20Oct09 - K9LA33 Comparison - MUF Close, but there are differences – especially around sunrise and sunset Close, but there are differences – especially around sunrise and sunset The difference is how the F 2 region is represented in the model The difference is how the F 2 region is represented in the model –VOACAP is database of numerical coefficients –Frickers equations in W6ELProp simplified this to 23 equations (1 main function + 22 modifying functions)

34 PVRC Webinar - 20Oct09 - K9LA34 Comparison – Signal Strength In general W6ELProp predicts higher signal strengths In general W6ELProp predicts higher signal strengths VOACAP is more realistic with respect to signal strength VOACAP is more realistic with respect to signal strength

35 PVRC Webinar - 20Oct09 - K9LA35 The Mapping Feature in W6ELProp This is a great tool for low band operating This is a great tool for low band operating Recently on the topband reflector SM2EKM told of a 160m QSO with KH6AT in late December at local noon Recently on the topband reflector SM2EKM told of a 160m QSO with KH6AT in late December at local noon Without digging any farther, this sounds like a very unusual QSO Without digging any farther, this sounds like a very unusual QSO

36 PVRC Webinar - 20Oct09 - K9LA36 SM to KH6 in Dec at SM Noon Path on SM end is perpendicular to the terminator Path on SM end is perpendicular to the terminator –RF from SM encounters the D region right around the terminator –But the solar zenith angle is high Rest of path is in darkness Rest of path is in darkness A index and K index are important for this over-the-pole path A index and K index are important for this over-the-pole path –Were at zero for a couple days

37 PVRC Webinar - 20Oct09 - K9LA37 Summary We dont have daily predictions We dont have daily predictions Predictions are statistical over a months time frame Predictions are statistical over a months time frame All prediction software is based on the correlation between a smoothed solar index and monthly median ionospheric parameters All prediction software is based on the correlation between a smoothed solar index and monthly median ionospheric parameters Many good programs out there with different presentation formats and different bells and whistles Many good programs out there with different presentation formats and different bells and whistles –Dont forget the predictions in the 21 st Edition of the ARRL Antenna Book CD by Dean N6BV VOACAP predictions to/from more than 170 locations VOACAP predictions to/from more than 170 locations Only give signal strength and dont include the WARC bands Only give signal strength and dont include the WARC bands Choose the one you like the best Choose the one you like the best –VOACAP considered the standard –Several use the VOACAP engine Interested in validating a prediction? Interested in validating a prediction? –Visit mysite.verizon.net/k9la/Validating_Propagation_Predictions.pdf

38 PVRC Webinar - 20Oct09 - K9LA38 Q & A This PowerPoint presentation is at And stay tuned for another PVRC propagation webinar – the topic will be Disturbances to Propagation


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