Getting Started with Propagation Prediction

To generate a propagation forecast for a QSO between your QTH and a DX location,

  1. select the Parameters tab in PropView's Main window

  2. in the Conditions panel

    1. set the forecast Date (this textbox will aready be set to the current date)

    2. type the current solar flux into the SFI textbox; if you are running SpotCollector, the textbox will already contain the solar flux from the most recent WWV spot

    3. leave the Avail % textbox set to 10

  3. in the Transmitter panel

    1. type your QTH's latitude and longitude into the Latitude and Longitude textboxes (e.g. 42 22' N and 98 45' W); if you are running DXView, these textboxes will already contain your QTH's location

    2. leave the TakeOff textbox set to 3

    3. type your transmitter power (in watts) into the Power textbox

    4. select either a Short or Long path forecast; if you're just getting started with HF propagation, choose Short path -- the most direct route between your QTH and the DX QTH.

  4. in the Receiver panel

    1. type the DX location's latitude and longitude into the Latitude and Longitude textboxes (e.g. 40 15' S and 150 12' E); if you are running DXView, these textboxes will already contain the selected location's latitude and longitude

    2. select the Man-made noise level like to be experienced by the DX station; for an optimistic forecast, choose Remote

  5. click the Predict button; PropView will compute a forecast, and produce a graphical display on the Main window's Prediction tab

Interpreting a PropView forecast graph

After generating a prediction for propagation between two locations, check the Prediction tab's Show Critical Frequencies box and uncheck its Show Open Bands box.

PropView's forecasts are depicted on a graph of frequency (vertical access) vs. UTC time (horizontal axis):

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.

At any specified time, you can identify which frequencies will likely support communication between your QTH and the DX location: 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, 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 the Show Open Bands box:

PropView will display horizontal lines representing ham bands lying between the LUF and statistical MUF; the thickness of these horizontal lines conveys the likelihood of an opening: 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 the Show Critical Frequencies box, the relationship between the horizontal lines and the critical frequency curves should be apparent:

Below the forecast graph's labeled time axis, two multicolored horizontal bars labelled Xmitter and Rcvr show daytime (yellow), twilight (gray), and nightime (black) conditions at your QTH and the DX location respectively. For the low bands -- 160m, 80m, 60m, and 40m -- twilight or dark conditions at both your QTH and the DX location are generally required:

Post a question or suggestion on the DXLab reflector

Getting Started with DXLab

Propagation (last edited 2014-10-04 06:38:40 by AA6YQ)