Specifications

Channel Master Operation Manual
page 80 Teledyne RD Instruments
are the horizontal water profiling beams. Beam 4 is the vertical beam.
Beam 3 is unused electronics. The test contains four parts.
Part 1 - The Channel Master pings without transmitting and displays the re-
sult of an autocorrelation function performed on the received ambient sound
and internal electrical noise over 15 lag periods. Lag time can be calculated
from the sample rate at the bottom line of the output. Lag = 1/sample rate.
The receive path contains a band-pass filter that limits the correlation time
of the received signal for beams 1 and 2 to a few lag times. Longer correla-
tion times indicate a problem such as interference from a radio station.
Beams 3 and 4 cannot be so easily interpreted because of electrical and fre-
quency differences.
Part 2 - The received signal is split into two parts and hard limited into 1's
and 0's. A random signal should have about 50% of each. A duty cycle
much different from 50% is an indication of a problem.
Part 3 - Random electrical noise sampled at two different times have some
level of correlation. This correlation is called the noise floor. It can be
seen at the tail end of the 15 lags.
A higher than usual noise floor may indicate the presence of a signal that
self correlates better than random noise or a hardware problem. The noise
floor should be higher at high gain and lower at low gain. Too small a dif-
ference can indicate a problem in the demodulator, receiver, or RSSI
switching circuitry.
Part 4 - For beams 1 and 2, the bandwidth of the band-pass filter can be cal-
culated by integrating correlation over lag times.
>PT3
Receive Path Test (Hard Limited):
H-Gain W-BW L-Gain W-BW H-Gain N-BW L-Gain N-BW
Correlation Magnitude (percent)
Lag Bm1 Bm2 Bm3 Bm4 Bm1 Bm2 Bm3 Bm4 Bm1 Bm2 Bm3 Bm4 Bm1 Bm2 Bm3 Bm4
0 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100 100
1 83 83 86 85 80 79 79 90 79 81 81 93 78 77 78 93
2 51 51 55 70 46 41 41 71 43 44 45 79 42 41 41 77
3 24 26 28 49 18 15 16 49 16 18 19 61 16 16 15 57
4 9 13 12 33 6 2 3 28 3 3 7 43 6 5 5 38
5 5 8 6 20 2 0 4 14 2 3 6 30 5 3 6 22
6 5 6 5 10 4 2 5 4 1 4 6 20 3 3 7 10
7 5 6 5 6 4 1 3 3 3 3 6 13 1 1 6 3
8 4 5 4 4 2 3 1 6 4 1 5 10 2 2 3 4
9 3 3 4 4 1 4 2 6 4 4 1 8 5 2 2 7
10 2 2 4 3 2 4 3 7 3 5 2 8 7 1 2 8
11 3 3 4 6 2 5 3 8 0 5 2 9 6 1 2 7
12 1 5 4 5 4 6 3 8 2 3 3 11 6 3 3 5
13 0 4 3 4 5 6 3 7 2 1 2 12 6 5 3 3
14 2 3 3 4 6 8 2 6 2 1 3 12 6 3 5 1
15 1 3 2 5 5 7 3 5 4 1 4 13 3 3 6 1
Sin Duty Cycle (percent)
44 49 50 54 51 52 51 54 46 51 52 65 51 52 51 54
Cos Duty Cycle (percent)
51 48 50 54 51 49 50 51 49 48 53 62 51 52 53 58
RSSI Noise Floor (counts)
66 50 66 62 57 41 57 52 73 58 74 70 57 41 57 52
BandWidth (kHz)
369 350 347 293 379 383 394 291 99 97 94 60 94 100 95 70
Sample Rate (Hz)
1228800 1228800 307200 307200