Teledyne ADFM Analog Output Module, Technical Manual, Page: 107 / 156

ADFM Commands
PT1 – Board Level Receive Test
Purpose: This test displays receive path characteristics with lower
thresholds than PT3 since the preamplifier in the transducer is
disconnected during the test.
Format: PT1
Description: The test result is given as four nibbles (1 nibble = 4 bits).
Each nibble represents the result for a particular beam (most
significant nibble = beam 1, least significant nibble = beam 4).
In this example, we only describe which bit is set for beam 4
for a given failure type. This test has three parts:
Part 1
: The ADFM pings without transmitting and displays the
result of an auto-correlation function performed over 0 to 7
Lag periods. Ideally, we should see high correlation at near-
zero lags, and then see the correlation magnitude get smaller
quickly toward larger Lags. High correlation values at larger
Lags may indicate interference.
Part 2
: The ADCP compares the RSSI value at high-gain vs.
low-gain. This is not applicable to the ADFM. However, the
recorded RSSI value is applicable, and is compared to a fac-
tory threshold. High RSSI levels may also indicate interfer-
ence.
Part 3
: The ADFM displays the Demodulator Hard-limiter
bias values (DAC values. These values should be consistent
between beams and tests; however, some number of counts
deviation are allowed.
>pt1
Correlation Magnitude:
Lag Bm1 Bm2 Bm3 Bm4 Bm5
0 255 255 255 255 255
1 235 230 232 231 241
2 187 171 176 174 207
3 140 110 121 115 171
4 106 69 79 73 141
5 82 46 57 46 117
6 63 33 42 30 92
7 46 26 29 21 71
High Gain RSSI: 50 48 51 49 56
DAC Sin: 200
DAC Cos: 198
Duty: 48 48, LPF: 0
Receive Test Results = $00006000 ... PASS
ADFM Technical Manual (January 2000) page C-27