Warrington Amateur Radio Club Rigs ~ WJST"

The first mode implemented, and the one that has given WSJT its wide initial popularity, is called FSK441. It is designed for high speed meteor scatter (HSMS) communication using "pings" reflected from the underdense ionization trails of random meteors at about 100 km height. Such pings are typically a few dB above the noise and last for anywhere from ten to a few hundred milliseconds.

FSK441 uses Frequency Shift Keying at a baud rate of 441 Hz. Four distinct tones are used, namely 882, 1323, 1764, and 2205 Hz. Each encoded character uses three tone intervals and therefore requires 3/441 seconds (approximatelt 2.3 ms) for its transmission. FSK441 accommodates a potential "alphabet" of 48 characters. The present encoding scheme uses 43 of these characters, the same ones used in the PUA-43 alphabet.

The present encoding of each character is defined in the table below. The four tones are labeled 0-3 for the tones 882 through 2205 Hz, in increasing order. The four possible "single-tone" encodings, namely 000, 111, 222, and 333, are reserved in WSJT for special use as shorthand messages. (These characters sent repeatedly amount to pure single-frequency carriers, and their pings are easily recognized by the software and by the human ear.) The present definition of the
shorthand messages is respectively "R26", "R27", "RRR", and "73". These messages are very widely used in North American HSMS
communications.

	Not your typical meteor. An "earthgrazer" Leonid, when the radiant is very low on the horizon.
"A huge fireball imaged with 75 degree FOV Gen 2 intensifier. The meteor starts just above Jupiter, the bright object in the upper center of frame."

The Geminids meteor shower
lasts from Dec 7 - Dec 17,
peaks on Dec 14 th, 2001 / 0350UT±6hrs
ZHR : 120 meteors/hour, velocity 34.4km/sec, unsymmetric, fades fast

The Geminids meteor shower is active during the period Dec 6th - Dec 19th. Upon reaching maximum activity during December 13 to 14 (Solar longitude=261.3°) , hourly rates are typical near 80, while the radiant is at RA=112.5° , DECL=32.6° . The meteors are described as rapid and yellowish, with about 4% displaying persistent trains. They possess an average magnitude near 2.4 . Visual observations have shown this shower to possess a very sharp peak of activity, with hourly rates remaining above a value of half the maximum for about two days.

Character Tones
Number sent Character
--------------------------
0 000 [reserved]
1 001 1
2 002 2
3 003 3
4 010 4
5 011 5
6 012 6
7 013 7
8 020 8
9 021 9
10 022 .
11 023 ,
12 030 ?
13 031 /
14 032 #
15 033 <Space>
16 100 $
17 101 A
18 102 B
19 103 C
20 110 D
21 111 [reserved]
22 112 F
23 113 G
24 120 H
25 121 I
26 122 J
27 123 K
28 130 L
29 131 M
30 132 N
31 133 O
32 200 P
33 201 Q
34 202 R
35 203 S
36 210 T
37 211 U
38 212 V
39 213 W
40 220 X
41 221 Y
42 222 [reserved]
43 223 0
44 230 E
45 231 Z
46 232
47 233
...
63 333 [reserved]

WSJT is the name of a computer program. It stands for "Weak Signal communications, by K1JT", and plans call for the program to include more than one communication mode.