SECTION 2: SPECIFICATIONS 2-2
Acoustic Specifications
The acoustic specifications for the 8242XS unit are described in the following sub-sections.
192 dB re 1 µPascal-meter
Transponder SNR
> or = 44 dB re root Hz for jitter < +/- 0.5 milliseconds (3 σT).
Jitter =+/- 0.1 milliseconds for noise-free field
Minimum interrogate pulse width
Transmit/Reply source level
192 dB re 1 µPascal-meter
10 milliseconds (standard unit)
12.5 milliseconds (standard unit)
-100 dB re 1 µPascal-meter
Hard-limited (2000 Hz / 330 Hz bandwidths)
Table 2-2: Acoustic Specifications
BACS Command Structure
The BACS’ command structure consists of two 8-bit words separated by a 5-sec interval. Each word is
comprised of 8 bits from a 16-bit command. The 16-bit command is a 15 bit, 11 block cyclic code with an
overall parity bit appended to the end to form a 16-bit code with a minimum Hamming distance of 4 bits.
Two transitions are required within each word, and no repetitions of words are allowed in a command.
General to 8000 series – Binary FSK
Six (see TABLE 2-4) for full breakdown of pairs
Structure
Two successive 8 bit words with a 5 sec. interval between them.
Each word comprised of 8 bits from a 16 bit command. The 16 bit command is a 15,
11 block cyclic code with an overall parity bit appended to the end to form a 16, 11
code with a minimum Hamming distance of 4 bits.
Additionally, two transitions are required within each word, and no repetitions of
words are allowed in a command.
Total command
capacity per tone pair
2,000 or 12,000 commands for six tone pairs
Release, Disable Transponder, Enable Transponder
Table 2-3: BACS Command Structure Specifications
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