PVRC Webinar - 20Oct09 - PVRC Webinar - 20Oct09 - K9LA K9LA 1 Propagation Prediction Propagation Prediction Programs: Programs: Their Development and Their Development and Use Use Carl Luetzelschwab K9LA Carl Luetzelschwab K9LA [email protected][email protected]http://mysite.verizon.net/k9la http://mysite.verizon.net/k9la
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PVRC Webinar - 20Oct09 - K9LA 1 Propagation Prediction Programs: Their Development and Use Carl Luetzelschwab K9LA [email protected].
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What We’re Going to CoverWhat We’re Going to Cover
• How the ionosphere formsHow the ionosphere forms• Measuring the ionosphereMeasuring the ionosphere• Solar-ionosphere correlationSolar-ionosphere correlation• Variability of the ionosphereVariability of the ionosphere• Sample predictionSample prediction• Understanding prediction outputsUnderstanding prediction outputs
This presentation will be on the PVRC websitevisit http://www.pvrc.org/index.htmlclick on the ‘PVRC Webinars’ link at the top
The AtmosphereThe Atmosphere• Composition of the atmosphereComposition of the atmosphere
– 78.1% nitrogen, 20.9% oxygen, 1% other gases78.1% nitrogen, 20.9% oxygen, 1% other gases• Species that are important in the ionosphereSpecies that are important in the ionosphere
• Maximum wavelength is longest wavelength of radiation Maximum wavelength is longest wavelength of radiation that can cause ionizationthat can cause ionization– Related to ionization potential through Planck’s ConstantRelated to ionization potential through Planck’s Constant
• 10.7 cm = 107,000,000 nm10.7 cm = 107,000,000 nm– 10.7 cm solar flux doesn’t ionize anything10.7 cm solar flux doesn’t ionize anything– It is a proxy (substitute) for the true ionizing radiationIt is a proxy (substitute) for the true ionizing radiation
• The sunspot number is also a proxyThe sunspot number is also a proxy
• Visible light = 400 to 700 nmVisible light = 400 to 700 nm
• As radiation progresses down through the As radiation progresses down through the atmosphere, it is absorbed by the aforementioned atmosphere, it is absorbed by the aforementioned species in the process of ionizationspecies in the process of ionization– Energy reduced as it proceeds lowerEnergy reduced as it proceeds lower– Need higher energy radiation (shorter wavelengths) to get Need higher energy radiation (shorter wavelengths) to get
lowerlower• True ionizing radiation can be summarized as True ionizing radiation can be summarized as
followsfollows– .1 to 1 nm and 121.5 nm for the D region.1 to 1 nm and 121.5 nm for the D region
• 121.5 nm (Lyman-121.5 nm (Lyman- hydrogen spectral line) is the result of a hydrogen spectral line) is the result of a minimum in the absorption coefficient of Ominimum in the absorption coefficient of O22 and N and N22
– It goes through the higher altitudes easily, and ionizes NO at It goes through the higher altitudes easily, and ionizes NO at lower altitudes to give us daytime absorptionlower altitudes to give us daytime absorption
– 1 to 10 nm for the E region1 to 10 nm for the E region– 10 to 100 nm for the F10 to 100 nm for the F22 region region Sunspots and 10.7 cm solar flux
Introduction to IonosondesIntroduction to Ionosondes
• To make predictions, you need a model of the To make predictions, you need a model of the ionosphereionosphere
• Model developed from ionosonde dataModel developed from ionosonde data• Most ionosondes are equivalent to swept-Most ionosondes are equivalent to swept-
frequency radars that look frequency radars that look straight upstraight up– Co-located transmitter and receiverCo-located transmitter and receiver– Also referred to as vertical ionosondes or vertically-Also referred to as vertical ionosondes or vertically-
incident ionosondesincident ionosondes• There are also oblique ionosondesThere are also oblique ionosondes
– Transmitter and receiver separatedTransmitter and receiver separated– Evaluate a specific pathEvaluate a specific path
What Does an Ionosonde What Does an Ionosonde Measure?Measure?
• It measures the time for a It measures the time for a wave to go up, to be turned wave to go up, to be turned around, and to come back around, and to come back downdown
• Thus the true measurement Thus the true measurement is time, not heightis time, not height
• This translates to This translates to virtualvirtual height assuming the speed height assuming the speed of light and mirror-like of light and mirror-like reflectionreflection
• The real wave does not get The real wave does not get as high as the virtual heightas high as the virtual height
An ionosonde measures time of flight, not altitude, at each frequency
Sample IonogramSample Ionogram• Red is ordinary wave, green Red is ordinary wave, green
is extraordinary waveis extraordinary wave• Critical frequencies are Critical frequencies are
highest frequencies that highest frequencies that are returned to Earth from are returned to Earth from each region at vertical each region at vertical incidenceincidence
• Electron density profile is Electron density profile is derived from the ordinary derived from the ordinary wave data (along with a wave data (along with a couple assumptions about couple assumptions about region thickness)region thickness)– Electron density anywhere Electron density anywhere
in the ionosphere is in the ionosphere is equivalent to a plasma equivalent to a plasma frequency through the frequency through the equation fequation fpp (Hz) = 9 x N (Hz) = 9 x N1/2 1/2
with N in electrons/mwith N in electrons/m33• E region and FE region and F22 region have maximums in electron density region have maximums in electron density
• FF11 region is inflection point in electron density region is inflection point in electron density
• D region not measuredD region not measured
• Nighttime data only consists of FNighttime data only consists of F22 region and sporadic E due to region and sporadic E due to TX ERP and RX sensitivity (limit is ~1.8 MHz)TX ERP and RX sensitivity (limit is ~1.8 MHz)
foE
foF1
foF2fxF2
electron density profile
daytime data
http://digisonde.haystack.edu
Note that we don’t see layers with gaps in between
Characterizing the Characterizing the IonosphereIonosphere• Ionosphere is characterized in terms of critical Ionosphere is characterized in terms of critical
frequencies (foE, foFfrequencies (foE, foF11, foF, foF22) and heights of ) and heights of maximum electron densities (hmE, hmFmaximum electron densities (hmE, hmF22))– Easier to use than electron densitiesEasier to use than electron densities
• Allows us to calculate propagation over Allows us to calculate propagation over oblique pathsoblique paths– MUF(2000)E = foE x M-Factor for E regionMUF(2000)E = foE x M-Factor for E region– MUF(3000)FMUF(3000)F22 = foF = foF22 x M-Factor for F x M-Factor for F22 region region
• Rule of thumb: E region M-factor ~ 5, FRule of thumb: E region M-factor ~ 5, F22 region M-factor ~ region M-factor ~ 33
for more on the M-Factor, visit http://mysite.verizon.net/k9la/The_M-Factor.pdf
• Many years of solar data and Many years of solar data and worldwide ionosonde data worldwide ionosonde data collectedcollected
• The task of the propagation The task of the propagation prediction developers was to prediction developers was to determine the correlation determine the correlation between solar data and between solar data and ionosonde dataionosonde data
• It would have been nice to find It would have been nice to find a correlation between what the a correlation between what the ionosphere was doing on a ionosphere was doing on a given day and what the Sun given day and what the Sun was doing on the same daywas doing on the same day
• August 2009August 2009– Zero sunspotsZero sunspots– Constant 10.7 cm Constant 10.7 cm
fluxflux
• No correlation between daily valuesNo correlation between daily values– Low of 11.6 MHz on August 14Low of 11.6 MHz on August 14– High of 21.5 MHz on August 16High of 21.5 MHz on August 16
• Indicates there are other factors in Indicates there are other factors in determining the ultimate ionizationdetermining the ultimate ionization
• Comment about CQ WW Phone 2007, 2008Comment about CQ WW Phone 2007, 2008
MUF(3000)F2 over Wallops Island (VA) Ionosonde at 1700 UTC
What Causes this What Causes this Variability?Variability?
• Rishbeth and Mendillo, Journal of Atmospheric and Solar-Rishbeth and Mendillo, Journal of Atmospheric and Solar-Terrestrial Physics, Vol 63, 2001, pp 1661-1680Terrestrial Physics, Vol 63, 2001, pp 1661-1680– Looked at 34 years of foFLooked at 34 years of foF22 data data– Used data from 13 ionosondesUsed data from 13 ionosondes– Day-to-day daytime variability (std dev/monthly mean) = 20%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%][20%]22 = [3%] = [3%]22 + [13%] + [13%]22 + [15%] + [15%]22
We Don’t Have Daily We Don’t Have Daily Predictions Predictions
• Day-to-day variability just too greatDay-to-day variability just too great• We have a good understanding of the solar influenceWe have a good understanding of the solar influence• We’re beginning to better understand the We’re beginning to better understand the
geomagnetic field influencegeomagnetic field influence– It’s a bit more than just “low K = good” and “high K = bad”It’s a bit more than just “low K = good” and “high K = bad”
• We are lacking a good understanding of how events in We are lacking a good understanding of how events in the lower atmosphere couple up to the ionospherethe lower atmosphere couple up to the ionosphere– This is a major reason why prediction programs don’t cover This is a major reason why prediction programs don’t cover
160m (along with the effect of the Earth’s magnetic field 160m (along with the effect of the Earth’s magnetic field through the electron-gyro frequency)through the electron-gyro frequency)• 160m RF doesn’t get as high into the ionosphere as the higher 160m RF doesn’t get as high into the ionosphere as the higher
frequenciesfrequencies– Doesn’t help that ionosondes don’t measure the lower Doesn’t help that ionosondes don’t measure the lower
ionosphere – especially at night when we chase DX on the low ionosphere – especially at night when we chase DX on the low bandsbands
• Our propagation prediction programs are based on the Our propagation prediction programs are based on the correlation between a smoothed solar index and monthly correlation between a smoothed solar index and monthly median ionospheric parametersmedian ionospheric parameters– Monthly median parameters can be represented in different waysMonthly median parameters can be represented in different ways
• Database of numerical coefficientsDatabase of numerical coefficients• EquationsEquations• International Reference IonosphereInternational Reference Ionosphere
• Our predictions programs are pretty accurate when the Our predictions programs are pretty accurate when the geomagnetic field is quietgeomagnetic field is quiet
• Real-time MUF maps seen on the web are kind of a misnomerReal-time MUF maps seen on the web are kind of a misnomer– If they use a smoothed solar index, then they’re monthly median If they use a smoothed solar index, then they’re monthly median
MUFsMUFs– If they use today’s solar flux or today’s sunspot number (maybe If they use today’s solar flux or today’s sunspot number (maybe
even with today’s A index), I don’t know what they are!even with today’s A index), I don’t know what they are!• Now it’s time to run a sample predictionNow it’s time to run a sample prediction
• October 2004October 2004– Smoothed sunspot number ~ 35 (smoothed solar flux ~ 91)Smoothed sunspot number ~ 35 (smoothed solar flux ~ 91)
• Are we ever going to see that again? Are we ever going to see that again? • AntennasAntennas
– Small Yagis on both ends = 12 dBi gainSmall Yagis on both ends = 12 dBi gain• PowerPower
– 1000 Watts on both ends1000 Watts on both ends• Bands and PathBands and Path
– 20m, 17m, 15m on the Short Path20m, 17m, 15m on the Short Path• We’ll use VOACAPWe’ll use VOACAP
– When you download VOACAP (comes with ICEPAC and When you download VOACAP (comes with ICEPAC and REC533), read the Technical Manual and User’s Manual – REC533), read the Technical Manual and User’s Manual – lots of good infolots of good info
– Controls the type of program analysis and the predictions Controls the type of program analysis and the predictions performedperformed
– Recommend using Method 30 (Short\Long Smoothing) most of Recommend using Method 30 (Short\Long Smoothing) most of the timethe time
– Methods 1 and 25 helpful for analysis of the ionosphereMethods 1 and 25 helpful for analysis of the ionosphere
• CoefficientsCoefficients– CCIR (International Radio Consultative Committee)CCIR (International Radio Consultative Committee)
• Shortcomings over oceans and in southern hemisphereShortcomings over oceans and in southern hemisphere• Most validatedMost validated
– URSI (International Union of Radio Scientists)URSI (International Union of Radio Scientists)• Rush, et al, used aeronomic theory to fill in the gapsRush, et al, used aeronomic theory to fill in the gaps
• GroupsGroups– Month.DayMonth.Day
• 10.00 means centered on the middle of October10.00 means centered on the middle of October• 10.05 means centered on the 510.05 means centered on the 5thth of October of October
– Defaults to URSI coefficients Defaults to URSI coefficients
• SystemSystem– NoiseNoise default is residentialdefault is residential– Min AngleMin Angle 1 degree (emulate obstructions to radiation)1 degree (emulate obstructions to radiation)– Req RelReq Rel default is 90%default is 90%– Req SNRReq SNR 48 dB in 1 Hz (13 dB in 3 KHz: 90% 48 dB in 1 Hz (13 dB in 3 KHz: 90%
intelligibility)intelligibility)– Multi TolMulti Tol default is 3 dBdefault is 3 dB– Multi DelMulti Del default is .1 millisecondsdefault is .1 milliseconds
• FprobFprob– Multipliers to increase or reduce MUFMultipliers to increase or reduce MUF
• Default is 1.00 for foE, foF1, foF2 and 0.00 for foEsDefault is 1.00 for foE, foF1, foF2 and 0.00 for foEsFor more details on setting up and running VOACAP, either visit http://lipas.uwasa.fi/~jpe/voacap/ by Jari OH6BG (lots of good info) or http://mysite.verizon.net/k9la/Downloading_and_Using_VOACAP.PDF
15m Signal Power15m Signal Power• -94 dBW (monthly median) = -64 dBm-94 dBW (monthly median) = -64 dBm• AssumeAssume
– S9 = -73 dBm (50 microvolts into 50S9 = -73 dBm (50 microvolts into 50ΩΩ))– one S-unit = 5 dBone S-unit = 5 dB
• typical of receivers I’ve measuredtypical of receivers I’ve measured– except below S3 or so it’s only a couple dB per S-unitexcept below S3 or so it’s 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 Variability about the monthly median from ionospheric
texts (for example, Supplement to Report 252-2, CCIR, texts (for example, Supplement to Report 252-2, CCIR, 1978)1978)
• Signal power could be from one S-unit higher to two S-units Signal power could be from one S-unit higher to two S-units lower on any given day on this pathlower on any given day on this path– S9 to 15 over 9 for this pathS9 to 15 over 9 for this path
• Rule of thumb – actual signal power for any path could be Rule of thumb – actual signal power for any path could be from a couple S-units higher to several S-units lower than from a couple S-units higher to several S-units lower than median on any given daymedian on any given day
Don’t make assumptions about your S-meter – measure it
What’s Different with What’s Different with W6ELProp?W6ELProp?
• Underlying concept is still the correlation between Underlying concept is still the correlation between a smoothed solar parameter and monthly median a smoothed solar parameter and monthly median ionospheric parametersionospheric parameters
• For foFFor foF22, W6ELProp uses equations developed by , W6ELProp uses equations developed by Raymond Fricker of the BBCRaymond Fricker of the BBC– VOACAP uses database of numerical coefficients to VOACAP uses database of numerical coefficients to
describe worldwide ionospheredescribe worldwide ionosphere– Another option is IRI (PropLab Pro)Another option is IRI (PropLab Pro)
• W6ELProp rigorously calculates signal strength W6ELProp rigorously calculates signal strength using CCIR methodsusing CCIR methods– VOACAP calibrated against actual measurementsVOACAP calibrated against actual measurements
For more details on setting up and running W6ELProp, visit http://mysite.verizon.net/k9la/Downloading_and_Using_W6ELProp.PDF
• Close, but there are Close, but there are differences – differences – especially around especially around sunrise and sunsetsunrise and sunset
• The difference is how The difference is how the Fthe F22 region is region is represented in the represented in the modelmodel– VOACAP is database VOACAP is database
of numerical of numerical coefficientscoefficients
– Fricker’s equations in Fricker’s equations in W6ELProp ‘simplified’ W6ELProp ‘simplified’ this to 23 equations this to 23 equations (1 main function + 22 (1 main function + 22 modifying functions)modifying functions)
The Mapping Feature in The Mapping Feature in W6ELPropW6ELProp
• This is a great tool for low band operatingThis is a great tool for low band operating• Recently on the topband reflector SM2EKM Recently on the topband reflector SM2EKM
told of a 160m QSO with KH6AT in late told of a 160m QSO with KH6AT in late December at December at local noonlocal noon
• Without digging any farther, this sounds Without digging any farther, this sounds like a very unusual QSOlike a very unusual QSO
SM to KH6 in Dec at SM SM to KH6 in Dec at SM NoonNoon
• Path on SM end is Path on SM end is perpendicular to the perpendicular to the terminatorterminator– RF from SM RF from SM
encounters the D encounters the D region right around region right around the terminatorthe terminator
– But the solar zenith But the solar zenith angle is highangle is high
• Rest of path is in Rest of path is in darknessdarkness
• A index and K index A index and K index are important for are important for this over-the-pole this over-the-pole pathpath– Were at zero for a Were at zero for a
SummarySummary• We don’t have daily predictionsWe don’t have daily predictions• Predictions are statistical over a month’s time framePredictions are statistical over a month’s time frame• All prediction software is based on the correlation between All prediction software is based on the correlation between
a smoothed solar index and monthly median ionospheric a smoothed solar index and monthly median ionospheric parametersparameters
• Many good programs out there with different presentation Many good programs out there with different presentation formats and different bells and whistlesformats and different bells and whistles– Don’t forget the predictions in the 21Don’t forget the predictions in the 21stst Edition of the ARRL Edition of the ARRL
Antenna Book CD by Dean N6BVAntenna Book CD by Dean N6BV• VOACAP predictions to/from more than 170 locationsVOACAP predictions to/from more than 170 locations• Only give signal strength and don’t include the WARC bandsOnly give signal strength and don’t include the WARC bands
• Choose the one you like the bestChoose the one you like the best– VOACAP considered the standardVOACAP considered the standard– Several use the VOACAP engineSeveral use the VOACAP engine
• Interested in validating a prediction?Interested in validating a prediction?– Visit Visit
This PowerPoint presentation is at This PowerPoint presentation is at http://mysite.verizon.net/k9lahttp://mysite.verizon.net/k9la
And stay tuned for another PVRC And stay tuned for another PVRC ‘propagation’ webinar – the topic ‘propagation’ webinar – the topic will be Disturbances to Propagationwill be Disturbances to Propagation