Table 1
Betty’s Chances of Hearing Amelia on a Harmonic
Probability (in percent, or chances out of 100) that the required Signal-to-Noise Ratio
would occur on 1 out of 20 days
Date,
Day,
SSN*
  
15525 kHz
18630 kHz
21735 kHz
24840 kHz
Xmtr Power Out (watts)
Xmtr Power Out (watts)
Xmtr Power Out (watts)
Xmtr Power Out (watts)
Hour†
50
5
1
0.5
0.1
50
5
1
0.5
0.1
50
5
1
0.5
0.1
50
5
1
0.5
0.1
July 2
Fri
91
1500
1
0
0
0
0
1
0
0
0
0
14
6
3
2
1
35
25
20
18
13
1600
0
0
0
0
0
0
0
0
0
0
15
6
3
2
1
34
23
17
15
11
1700
1
0
0
0
0
0
0
0
0
0
6
1
1
0
0
19
9
4
3
1
July 3
Sat
74
1500
1
0
0
0
0
1
0
0
0
0
22
13
8
7
4
31
23
18
16
12
1600
0
0
0
0
0
1
0
0
0
0
25
14
8
7
4
29
21
16
14
11
1700
3
1
1
1
0
1
0
0
0
0
7
2
1
0
0
21
10
5
4
2
July 4
Sun
65
1500
1
0
0
0
0
1
0
0
0
0
29
19
14
12
8
25
18
14
12
9
1600
0
0
0
0
0
15
5
2
1
0
26
16
11
9
6
26
19
15
13
10
1700
6
3
2
2
1
1
0
0
0
0
10
3
1
1
0
19
9
5
4
2
July 5
Mon
91
1500
1
0
0
0
0
1
0
0
0
0
15
7
3
3
1
35
26
20
18
14
1600
0
0
0
0
0
0
0
0
0
0
15
7
3
2
1
34
24
18
16
11
1700
1
0
0
0
0
0
0
0
0
0
6
1
1
0
0
19
9
4
3
1
July 6
Tue
108
1500
0
0
0
0
0
27
19
15
13
10
10
3
1
1
0
35
25
18
16
11
1600
0
0
0
0
0
0
0
0
0
0
7
2
1
0
0
24
22
16
13
9
1700
0
0
0
0
0
0
0
0
0
0
4
1
0
0
0
15
6
2
2
1
Jul 7
Wed
143
1500
0
0
0
0
0
0
0
0
0
0
1
0
0
0
0
15
6
3
2
1
1600
0
0
0
0
0
1
0
0
0
0
10
3
1
1
0
11
4
1
1
0
1700
0
0
0
0
0
13
8
6
5
3
1
0
0
0
0
7
2
1
0
0
Jul 8
Thur
185
1500
0
0
0
0
0
1
0
0
0
0
0
0
0
0
0
4
1
0
0
0
1600
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
3
1
0
0
0
1700
0
0
0
0
0
7
4
3
2
1
0
0
0
0
0
2
0
0
0
0
July 9
Fri
181
1500
0
0
0
0
0
1
1
0
0
0
0
0
0
0
0
4
1
0
0
0
1600
0
0
0
0
0
0
0
0
0
0
0
0
0
0
0
4
1
0
0
0
1700
0
0
0
0
0
1
0
0
0
0
0
0
0
0
0
3
1
0
0
0
Notes
* SSN = sunspot number for the date indicated, included to illustrate daily changes in propagation conditions.
† Hour = local hour at St. Petersburg, e.g., the 1500 hour extends from 1500 to 1600.