Detailed Propagation Predictions from VU7 to North America

Carl Luetzelschwab K9LA

Of the paths from VU7 to the three major Amateur Radio population centers of the world (Europe, Japan, and North America), the path to North America will be the toughest due to going through the polar areas (over the northern polar area for short path and over the southern polar area for long path). Because of minimal solar illumination on the short path in January 2007, long path will likely play an important role in working VU7.

To provide North American DXers the best opportunity to work VU7, detailed propagation predictions from VU7 to seven geographical areas in North America for January 15-25, 2007 have been made using VOACAP. These predictions are for 30m through 10m.

Detailed predictions for 160m and 80m are not given. The times of possible propagation on these two bands are determined by the times when the desired path is in darkness. These times can be calculated from your specific sunrise and sunset times and the sunrise and sunset times at VU7.

Assumptions

The pertinent assumptions for these detailed predictions are as follows:

Transmit power = 700W
Antenna gain = 5dBi for 30m and 40m, 12dBi for 20m - 10m
Noise environment = quiet rural
Minimum angle = 1 o
Signal-to-Noise Ratio (SNR) = 0dB in a 500Hz bandwidth (CW mode)
Minimum Discernible Signal (MDS) of receiver = -130dBm

Your specific openings may be longer or shorter than the predictions to follow depending on your transmit power, your antennas, your site, and your noise environment. Openings will be shorter for SSB due to needing a higher SNR than what is assumed in these predictions.

General Comments

For a QSO to be successful, two criteria must be met. First, there must be sufficient ionization along the path to get RF from VU7 to North America and vice versa. Second, the SNR must be sufficient to copy the signal.

Due to the day-to-day variation of the ionosphere, our propagation predictions give outputs that are statistical over a month’s time frame. Thus we have two probabilities: one with respect to ionization (what’s the probability of having sufficient ionization?) and one with respect to SNR (what’s the probability of having sufficient SNR?). Multiplying these two probabilities together gives us the overall probability of a successful QSO.

All Short Path Openings

The following table lists all possible SHORT PATH openings from the seven geographical areas in North America to VU7. These openings include openings with a very low probability of having enough ionization and openings with a very low probability of meeting the SNR requirement. All times are UTC.

All Long Path Openings

The following table lists all possible LONG PATH openings from the seven geographical areas in North America to VU7. These openings include openings with a very low probability of having enough ionization and openings with a very low probability of meeting the SNR requirement. All times are UTC.

Highest Probability Openings

The following table lists the ten hours from each of the seven geographical areas of North America to VU7 that offer the highest probability of a QSO. These are the ‘best times’ from the previous two tables. All times are UTC. Short path is designated with ‘sp’ and long path is designated with ‘lp’.

As can be seen, long path is likely to play an important role in North America working VU7.