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

PVRC Webinar - 20Oct09 - K9LAPVRC Webinar - 20Oct09 - K9LA 11

Propagation Prediction Propagation Prediction Programs:Programs:

Their Development and UseTheir Development and Use

Carl Luetzelschwab K9LACarl Luetzelschwab K9LA

[email protected]@arrl.nethttp://mysite.verizon.net/k9lahttp://mysite.verizon.net/k9la


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


How the Ionosphere Forms


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

ionization potential maximum wavelength

O (atomic oxygen) 13.61 eV 91.1 nm

O2 (molecular oxygen) 12.08 eV 102.7 nm

N2 (molecular nitrogen) 15.58 eV 79.6 nm

NO (nitric oxide) 9.25 eV 134 nm


True Ionizing RadiationTrue Ionizing Radiation

• 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

are proxies for the true ionizing radiation


Measuring the Ionosphere


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


Solar – Ionosphere Correlation


What’s the Correlation?What’s the Correlation?

• 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

solar data

ionosonde data

???


But That Didn’t HappenBut That Didn’t Happen

August 2009

• 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

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day of August 2009M

Hz

http://www.solen.info/solar/


So Now What?So Now What?

Not too good - the developers were forced to come up with a statistical model over a month’s time frame

Good – smoothed solar flux (or smoothed sunspot number) and monthly median parameters

R2 = .0615

R2 = .8637


How Do You Determine the How Do You Determine the Monthly Median?Monthly Median?day foF2

1 5.42 4.33 4.84 4.65 4.76 4.67 4.88 4.49 4.410 011 4.212 4.913 4.214 4.615 4.516 4.917 018 4.419 5.220 4.821 4.922 4.923 4.824 4.725 4.426 4.427 4.328 4.829 4.930 4.931 4.6

day foF211 4.213 4.22 4.327 4.38 4.49 4.418 4.425 4.426 4.415 4.54 4.66 4.614 4.631 4.65 4.724 4.73 4.87 4.820 4.823 4.828 4.812 4.916 4.921 4.922 4.929 4.930 4.919 5.21 5.4

raw data

put foF2 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)


Correlation Between SF and Correlation Between SF and SSNSSN

Smoothed solar flux φ12 = 63.75 + 0.728 R12 + 0.00089 (R12)2

Smoothed sunspot numberR12 = (93918.4 + 1117.3 φ12)1/2 – 406.37

Using these equations to convert between daily solar flux and daily sunspot number results in a lot of uncertainty


Variability of the Ionosphere


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


Is the Ionosphere In Step?Is the Ionosphere In Step?

• 3000 km MUF 3000 km MUF over Millstone over Millstone Hill and Hill and Wallops IslandWallops Island

• Separated by Separated by 653 km = 408 653 km = 408 milesmiles

• Several periods Several periods show up when show up when the ionosphere the ionosphere was going was going opposite waysopposite ways

• Worldwide Worldwide ionosphere not ionosphere not necessarily in necessarily in stepstep


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


Summary So FarSummary So Far

• 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

We don’t have daily predictions


Sample Prediction


K9LA to ZFK9LA to ZF• Latitudes / longitudesLatitudes / longitudes

– K9LA = 41.0N / 85.0WK9LA = 41.0N / 85.0W– ZF = 19.5N / 80.5WZF = 19.5N / 80.5W

• 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


VOACAP Input ParametersVOACAP Input Parameters• MethodMethod

– 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


VOACAP Input ParametersVOACAP Input Parameters

• 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


Prediction PrintoutPrediction Printout 13.0 20.9 14.1 18.1 21.2 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 FREQ 1F2 1F2 1F2 1F2 - - - - - - - - MODE 10.0 4.7 5.5 10.0 - - - - - - - - TANGLE 8.6 8.4 8.4 8.6 - - - - - - - - DELAY 347 222 240 347 - - - - - - - - V HITE 0.50 0.99 0.83 0.46 - - - - - - - - MUFday 123 112 113 124 - - - - - - - - LOSS 28 36 37 27 - - - - - - - - DBU -93 -82 -83 -94 - - - - - - - - S DBW -168 -163 -166 -168 - - - - - - - - N DBW 75 80 83 74 - - - - - - - - SNR -27 -32 -35 -26 - - - - - - - - RPWRG 0.90 1.00 1.00 0.89 - - - - - - - - REL 0.00 0.00 0.00 0.00 - - - - - - - - MPROB 1.00 1.00 1.00 1.00 - - - - - - - - S PRB 25.0 8.4 12.5 25.0 - - - - - - - - SIG LW 13.1 4.9 5.3 14.0 - - - - - - - - SIG UP 26.8 12.6 15.7 26.8 - - - - - - - - SNR LW 14.3 7.2 7.8 15.2 - - - - - - - - SNR UP 12.0 12.0 12.0 12.0 - - - - - - - - TGAIN 12.0 12.0 12.0 12.0 - - - - - - - - RGAIN 75 80 83 74 - - - - - - - - SNRxx


Understanding Prediction Outputs


Focus on 15m at 1300 UTCFocus on 15m at 1300 UTC 13.0 20.9 14.1 18.1 21.2 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 FREQ 1F2 1F2 1F2 1F2 - - - - - - - - MODE 10.0 4.7 5.5 10.0 - - - - - - - - TANGLE 8.6 8.4 8.4 8.6 - - - - - - - - DELAY 347 222 240 347 - - - - - - - - V HITE 0.50 0.99 0.83 0.46 - - - - - - - - MUFday 123 112 113 124 - - - - - - - - LOSS 28 36 37 27 - - - - - - - - DBU -93 -82 -83 -94 - - - - - - - - S DBW -168 -163 -166 -168 - - - - - - - - N DBW 75 80 83 74 - - - - - - - - SNR -27 -32 -35 -26 - - - - - - - - RPWRG 0.90 1.00 1.00 0.89 - - - - - - - - REL 0.00 0.00 0.00 0.00 - - - - - - - - MPROB 1.00 1.00 1.00 1.00 - - - - - - - - S PRB 25.0 8.4 12.5 25.0 - - - - - - - - SIG LW 13.1 4.9 5.3 14.0 - - - - - - - - SIG UP 26.8 12.6 15.7 26.8 - - - - - - - - SNR LW 14.3 7.2 7.8 15.2 - - - - - - - - SNR UP 12.0 12.0 12.0 12.0 - - - - - - - - TGAIN 12.0 12.0 12.0 12.0 - - - - - - - - RGAIN 75 80 83 74 - - - - - - - - SNRxx

monthly median MUF

time

MUFday for 15m

signal power


15m Openings at 1300 UTC15m Openings at 1300 UTC• 20.9 MHz (monthly 20.9 MHz (monthly

median)median)– Enough ionization on Enough ionization on

half the days of the half the days of the monthmonth

• 21.2 MHz21.2 MHz– Enough ionization Enough ionization

on .46 x 31 = 14 on .46 x 31 = 14 days of the monthdays of the month

• 14 MHz and below14 MHz and below– Enough ionization Enough ionization

every day of the every day of the monthmonth

• 24.9 MHz24.9 MHz– Enough ionization on Enough ionization on

1 day of the month1 day of the month• 28.3 MHz28.3 MHz

– Not enough ionization Not enough ionization on any dayon any dayWe can’t predict which days are the

“good” days

MUF Plot

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30

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

MUFday(multiply by 31 to get the number of days in the month)

MH

z


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

S9+10 -63 dBmS9 -73 dBmS8 -78 dBmS7 -83 dBmS6 -88 dBmS5 -93 dBmS4 -98 dBmS3 -103 dBmS2 -108 dBmS1 -113 dBm


VOACAP vs VOACAP vs W6ELPropW6ELProp


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


Comparison - MUFComparison - MUF

K9LA to ZF, October 2003

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time, UTC

MU

F, M

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W6ELProp

VOACAP

• 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)


Comparison – Signal Comparison – Signal StrengthStrength

• In general In general W6ELProp W6ELProp predicts higher predicts higher signal signal strengthsstrengths

• VOACAP is VOACAP is more realistic more realistic with respect to with respect to signal strengthsignal strength

K9LA to ZF, October 2003

-90-85-80-75-70-65-60-55-50-45-40

1 3 5 7 9 11 13 15 17 19 21 23

time, UTC

sig

nal

po

wer

, d

Bm

W6ELProp

VOACAP


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

couple dayscouple days


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

mysite.verizon.net/k9la/Validating_Propagation_Predictions.pdfmysite.verizon.net/k9la/Validating_Propagation_Predictions.pdf


Q & AQ & A

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

Documents

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