User's Manual

Rev B
24
the display. Event_Log, running in frequency priority mode, only scans the
auxiliary antennas when a valid signal is detected on the associated master, so the
presence or absence of entries for A1, A2, A4 and A5 signify the success or failure of
the program to acquire signals on M0 and M1.
The test sequence consisted of 12 scan cycles with antennas attached followed by
13 cycles (shaded rows) with the antennas disconnected.
149.660 MHz 149.600 MHz
M0 A1 A2 M1 A4 A5 M0 A1 A2 M1 A4 A5
50 50 30 30 50 30 50 30 50 30
31 32 22 22 31 21 35 50 30 24 35 24
23 37 25 25 37 24 25 35 24 21
18 36 27 18 36 25 22 19 24 19
15 24 28 21 35 27 15 17 18 14
14 28 29 24 39 28 11 26 22 15
12 30 29 25 42 20 21 12 18 12
15 28 21 18 27 15 18 23 16 17 17 16
16 29 16 15 19 14 16 17 15 15 15 20
25 35 20 19 28 18 15 14 14 19 14 19
20 23 16 16 21 22 24 23 18 18
28 30 20 14 16 24 22 19 16 28 23 16
20 13 19 19
28 18 28 22
34 21 34 24
38 24 38 26
42 21 16 25 42 27
44 29 20 27 44 28
46 35 23 28 46 29
47 39 25 29 47 29
48 42 27 29 48 30
49 44 28 30 49 30
49 46 29 30 49 30
50 47 29 30 50 30
50 48 30 30 50 30
Since the noise at both frequencies was bursty, the gains in the first half of the
trial can be seen to fluctuate, while being gradually reduced from their set values.
In general, channel 2 (149,600 MHz) exhibited the more “stationary” noise statistics,
since coded transmitter noise bursts were usually present during a scan, and indeed
the gain reduction series shows a lower variance than for the channel in which the
interference was very strong but much more intermittent. Both channels can be
seen to recover, in the absence of noise, at more or less the same rate.

This record is from Event_Log version W9, in which a global noise reduction system is used
(adaptive AGC started with version W16).
OPTIMIZING NOISE PERFORMANCE IN EVENT_LOG