[PPRAANet] Winlink question

Thu Jan 10 14:39:50 EST 2019

Last night I presented on Winlink and several folks had questions about how the program knew what gateway stations I would be able to connect with on HF.

When you install the program, it will populate the program with all the known Winlink gateway stations at that time.  You can periodically update this list over the air or over the internet -- I recommend using the internet whenever it is available.  Each of the stations will have a grid location tied to it.  You will input your own grid location when you set up the program.

Using these grid locations and current solar weather, the program will calculate the Maximum Usable Frequency (MUF), Frequency of Optimum Traffic (FOT), and Lowest Usable Frequency (LUF) between your locations for each hour of the day. It compares these calculations with the frequencies that the gateway operates on and gives you a simple to read quality and reliability percentage prediction.  You can then chose a gateway station based on these predictions, or let the Winlink software choose for you.

Let's use VOACAP, a popular propagation prediction system, to demonstrate.  I will use the online version (http://www.voacap.com/) so you can play along if you want.  I click on "Point to Point Predictions", which opens up another window or tab.  You should see a world map.  Near the top of the map, you will see two rows, "Select TX QTH" and "Select RX QTH".  For the TX QTH, I will go across to "or set Grid" and type in DM78ov for my home location.  I will put in a grid of CN87qi as a RX QTH for a family member in Washington state.  Even with the default settings, I can now click on the "Prop Wheel" button on the right side of the display and a propagation prediction will show up.  To read the wheel, the time of day (UTC) is each radial of the wheel, going clockwise. The HF band is each concentric circle going from lowest frequency in the center to highest on the outside.  The prediction of propagation is displayed by the color of each segment.  To be more accurate, it is best to change the antennas, settings, mode, and power to reflect your actual circumstances -- for me I would use SSB, 50 Watts, and a dipole at 33 ft for all bands at both locations.  For what I just ran, here are my best bands to use by UTC(Z) hour:

0000Z = 30 meters
0100Z = 60 meters
0200Z = 40 meters
0300Z = 80 meters
0400Z = tie 80 and 60 meters
0500Z = 60 meters
0600Z = 60 meters
0700Z = 60 meters
0800Z = 40 meters
0900Z = 40 meters
1000Z = 40 meters
1100Z = 40 meters
1200Z = 60 meters
1300Z = 60 meters
1400Z = 40 meters
1500Z = 40 meters
1600Z = 30 meters
1700Z = 30 meters
1800Z = 20 meters
1900Z = 20 meters
2000Z = 20 meters
2100Z = 20 meters
2200Z = 20 meters
2300Z = 20 meters

Keep in mind these are all just predictions.  Actual results may, and likely will, vary.

John Bloodgood, KD0SFY
Emergency Coordinator & Public Information Officer
Region 2 District 2, Colorado ARES (Pikes Peak ARES)
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Joint USAF/NOAA Solar Geophysical Activity Report and Forecast SDF Number 9 Issued at 2200Z on 09 Jan 2019

IA. Analysis of Solar Active Regions and Activity from 08/2100Z to 09/2100Z: Solar activity has been at very low levels for the past 24 hours. There are currently 0 numbered sunspot regions on the disk.

IB. Solar Activity Forecast: Solar activity is expected to be very low on days one, two, and three (10 Jan, 11 Jan, 12 Jan).

IIA. Geophysical Activity Summary 08/2100Z to 09/2100Z: The geomagnetic field has been at quiet levels for the past 24 hours. Solar wind speed reached a peak of 452 km/s at 09/0109Z. Total IMF reached 6 nT at 08/2149Z. The maximum southward component of Bz reached -4 nT at 09/0100Z. Electrons greater than 2 MeV at geosynchronous orbit reached a peak level of 1978 pfu.

IIB. Geophysical Activity Forecast: The geomagnetic field is expected to be at quiet levels on days one and two (10 Jan, 11 Jan) and quiet to unsettled levels on day three (12 Jan).

III. Event probabilities
10 Jan-12 Jan
Class M       01/01/01

Class X        01/01/01

Proton        01/01/01

PCAF green

IV. Penticton 10.7 cm Flux
Observed

09 Jan                         072

Predicted

10 Jan-12 Jan              071/070/070
90 Day Mean

09 Jan                         070

V. Geomagnetic A Indices
Observed Afr/Ap

08 Jan                    005/005

Estimated Afr/Ap

09 Jan                    003/005

Predicted Afr/Ap

10 Jan-12 Jan         006/005-005/005-008/008

VI. Geomagnetic Activity Probabilities

10 Jan-12 Jan
A. Middle Latitudes

Active                      10/10/15

Minor Storm            01/01/05

Major-severe storm 01/01/01
B. High Latitudes

Active                      15/15/15

Minor Storm            20/20/25

Major-severe storm 10/10/20
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