Getting Started with Propagation Prediction

Forecasting Propagation from a DX Station to Your Station

To forecast propagation from a DX station to your station,

  1. on the Configuration window's Prediction tab, set the Forecasting Engine panel to VOACAP SNR & Prob

  2. on the Configuration window's General tab, set the Distance Units panel to Miles or Kilometers, depending on how you'd prefer to see distances displayed

  3. on PropView's Main window, select the Parameters tab

  4. set the Prediction Direction panel to From the DX Station

  5. set the Prediction Path panel to Short

  6. in the Conditions panel

    1. set the forecast Date (double-click for the current UTC date)

    2. click the U button to the right of the SSN to update the Smoothed Sunspot Number

    3. click the U button to the right of the K-index to update the Geomagnetic K Index

    4. set the Avail to 50

    5. set the Mode selector to the mode you'll be using, e.g. CW, SSB, RTTY, or PSK31; this will set the Required SNR (in the box labeled SNR) based on the settings in the Mode-dependent Settings panel on the Configuration window's Prediction tab

  7. in the Your Station panel

    1. if you are not running DXView, type your QTH's latitude and longitude into the Lat and Lon textboxes respectively

      a in the Man-made noise level panel, choose the setting appropriate to your QTH

  8. in the DX Station panel

    1. if you're running DXView, type the DX station's callsign or DXCC entity prefix into its Main windows callsign box and strike the Enter key, or click a location on its world map; if you're not running DXView, type the DX location's latitude and longitude into the Lat and Lon textboxes respectively (e.g. 40 15' S and 150 12' E)

    2. set the Power panel to the DX station's estimated RF output power

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

Interpreting the Forecast

After generating a prediction, uncheck the Prediction tab's Plot Critical Frequencies box and check its Show Open Bands and Show Current Time boxes.

The forecast is a graph of frequency on the vertical axis vs. UTC time on the horizontal axis. Frequencies are labeled in megahertz along the left side of the forecast, and in meters along the right side.

Band openings are depicted as horizontal magenta lines; the thicker the horizontal line at a particular frequency at a particular time, the higher the probability that there will be an opening on that frequency at that time. The black vertical time line depicts the current UTC time, so its intersections with the horizontal magenta lines identify current band openings:

You can use your mouse to drag the time line to the left or right to make it easier to see exactly when openings strengthen or weaken. Doing so will uncheck the Show Current Time box; checking this box will return the time line to depicting the current time.

Text in the Prediction window's upper left corner identifies the engine used to generate the forecast, and the UTC date for which the forecast was generated:

As is highlighted in the screen shot above, text immediately above the the forecast graph specifies

To assess the strength and probability of an opening at a particular frequency and time, allow the mouse cursor to hover over the horizontal magenta line at that point; three values will appear:

  1. the estimated signal strength, in decibels
  2. the percentage of days in the current month during which the estimated signal strength will exceed the Required SNR specified in the SNR box in the Conditions panel on the Main window' Parameters tab (and in the text immediately above the forecast graph)

  3. the Propagation Mode, expressed as "hops" between ionospheric layers

In this forecast, placing the cursor on the 40m opening at 0400Z shows the estimated signal strength at 24 db, with 76% of the month's days exceeding the specified 10 db minimum SNR:

The 2F2 shown above means that propagation involves two F2 layer hops.

Below the forecast graph's labeled time axis, two multicolored horizontal bars labelled You and DX show daytime (yellow), twilight (gray), and nightime (black) conditions at your QTH and the DX Station's 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; the intervals of common darkness are red-circled in this screen shot:


You can immediately generate a long path forecast by clicking the Predict From panel's LP button; this panel is located in the Prediction panel's upper-right corner.

Before predicting the strength of your signal at the DX Station's location, return to the Main window's Parameters tab and

  1. set the Prediction Direction to To the DX Station

  2. in the Your Station panel, set the Takeoff to 3 and set the Power to your station's RF output power, in watts

  3. in the DX Station panel, set the Man-made noise level to reflect the likely conditions

Now you can select the Main window's Prediction panel and generate short path or long path forecasts for your signal strength by clicking the Predict To panel's SP or LP buttons respectively.

Predicting Propagation with Active DX Stations

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Getting Started with DXLab

Propagation (last edited 2016-08-22 19:26:01 by AA6YQ)