Forecasting Propagation

PropView forecasts the minimum and maximum useable frequencies between a transmitter in one specified location and a receiver in another specified location over the course of a specified day. This forecast is driven by settings that you enter on the Conditions, Transmitter, and Receiver panels in PropView's Parameters tab.

Conditions panel

Date	the day for which a forecast is to be generated, in the format dd-mmm-yyyy double-clicking on this textbox enters the current UTC date
SFI	the solar flux index broadcast by WWV at 18 minutes after each hour available via N6RT's propagation page
Avail %	the required circuit reliability, stated as a percentage representing the likelihood that signal quality will be acceptable

Transmitter panel

Latitude	the latitude component of the transmitter's location, in standard geographic format if DXView is installed, PropView sets this component to your QTH latitude
Longitude	the longitude component of the transmitter's location, in standard geographic format if DXView is installed, PropView sets this component to your QTH longitude
TakeOff	the transmit antenna's minimum takeoff angle, in degrees
Power	transmitter output power, in watts
Path	determines whether propagation will be predicted for the short path or for the long path between the transmitter and receiver

Receiver panel

Latitude	the latitude component of the receiver's location, in standard geographic format if DXView is installed, PropView sets this component to its currently-selected location
Longitude	the longitude component of the receiver's location, in standard geographic format if DXView is installed, PropView sets this component to its currently-selected location
Man-made noise level	characterizes the level of man-made noise at the receiver's location: remote rural residential industrial

Generating a Propagation Forecast

When the above settings have been specified, click the Predict button. If the Frequency-dependent Settings panel's Enable box is checked and Commander is running, PropView determines your transceiver's current operating frequency and updates the Transmitter panel's Takeoff and Power settings based on the values specified in the Frequency-dependent Settings panel for that band; if the Frequency-dependent Settings panel's Enable box is not checked, or if Commander is not running, then the Transmitter panel's Takeoff and Power settings are not modified. PropView then creates the scripts required to drive IonCap and then initiates IonCap. When IonCap has completed its computation, PropView scans the generated numeric forecast and renders it in a graphic display on its Prediction tab. Because IonCap is a DOS program, its initiation and execution can take several minutes on slower machines running some versions of Windows.

The generated display shows time on its horizontal access, and frequency on its vertical access. A frequency scale labeled in mHz is provided along the right margin, and a wavelength scale labeled in meters is provided along the left axis. Below the time axis, PropView displays two horizontal bars indicating the solar position at the transmitter and receiver locations; in these bars, yellow means "sun is up", black means "sun is down", and grey means "twilight".

The brown Vertical Time Index shows the current UTC time, but can be dragged to any time of day; check the Show Current Time box to make the Vertical Time Index resume tracking the current time.

If the Plot Critical Frequencies box is checked, PropView displays the following frequencies hour-by-hour

If the Show Open Bands box is checked, PropView displays horizontal lines for each amateur band for which propagation is possible. The width of each line indicates the likelihood that propagation will occur:

Interpreting PropView Graphs

After generating a prediction for propagation between two locations, check "Show Critical Frequencies" and uncheck "Show Open Bands". The black curve represents the lowest useable frequency (LUF) as a function of time. Any frequency lower than the black curve will not support communications due to absorption. The blue, green, and red curves provide a statistical range for the maximum useable frequency (MUF) as a function of time. The actual MUF will be at or above the blue curve with 90% confidence, at or above the green curve with 50% confidence, and at or above the red curve with 10% confidence. Any frequency above the actual MUF will not support communications, due to insufficient reflection. So at any specified time, you can identify which frequencies will likely support communication between the specified locations: they are bounded on the low-end by the black curve, and on the high-end by the statistical range between the blue and red curves. You can use the green curve as a kind of "expected MUF" curve; if you're an optimist, you use the red curve for this purpose. To make it easier to see what ham bands are open when, uncheck the "Show Critical Frequencies" box and check "Show Open Bands". Horizontal lines represent ham bands lying between the LUF and statistical MUF. The thickest lines indicates openings based on the 90% confidence MUF (the blue curve), and the thinnest lines indicate openings based on the 10% confidence MUF (the red curve). If you now check "Show Critical Frequencies", the relationship between horizontal lines and critical frequency curves should be apparent.