8212BM Просмотр технического описания (PDF) - Nippon Precision Circuits
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8212BM Datasheet PDF : 32 Pages
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SM8212B
(2) Code words (address and message signals)
Each code word comprises 32 bits as shown in table 2.
Table 2. Code word format
Code word
1 (MSB)
2 to 19
Address
0
Signal
Address bits
Bit number
20 to 21
Function bits
20 21 Function
0 0 A call
0 1 B call
1 0 C call
1 1 D call
22 to 31
32 (LSB)
Check bits
Even-parity bit
Message
Signal
1
Message bits
Check bits
Even-parity bit
1. The MSB is the address/message code word control bit. It is 0 for an address signal, and 1 for a message signal.
2. Bits 2 to 21 contain the address or message information.
3. Bits 22 to 31 are BCH(31,21) format generated check bits, where BCH(n,k) = BCH(word length, number of information bits).
4. The LSB is an even-parity bit for bits 1 to 31.
(3) Call number to call sign conversion
This conversion expands a 7-digit decimal call number
into a 21-bit binary call sign, as shown in figure 2.
After expansion, the high-order 18 bits are assigned to
bits 2 to 19 (address signal), and the low-order 3 bits are
the user-defined frame identification pattern, which is
stored in ID-ROM. The two function bits define which of
four call functions is active.
7-digit decimal call signal (gap code) (8 to 2000000)
1 23 4 5 67
MSB
21-bit binary conversion
LSB
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21
1 2 Call sign
0
Bits 2 to 19 (18 bits)
19 20 21 22
Frame
identification
pattern
31 32
Bits 22 to 31 (10 bits)
P
Flag : "0" = Adderss signal
Function bits
BCH(31, 21) generated check bits
Even-parity bit
(for bits 1 to 31)
Figure 2. Call number to call sign conversion
NIPPON PRECISION CIRCUITS-8
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