NIPPON PRECISION CIRCUITS-8

SM8212B

Each code word comprises 32 bits as shown in table 2.

Bit number

1 (MSB)

2 to 19

20 to 21

22 to 31

32 (LSB)

Address

Signal

Code word

Message

Signal

Function

20 21

00

A call

01

B call

10

C call

11

D call

Function bits

0

1

Address bits

Message bits

Check bits

Even-parity bit

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.

Table 2. Code word format

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.

(3) Call number to call sign conversion

1

2

3456

7

1234

56

789 10 11 12 13 14 15 16 17 18 19 20 21

MSB

LSB

7-digit decimal call signal (gap code) (8 to 2000000)

21-bit binary conversion

Call sign

0

1

2

19

20

21

32

31

22

Frame

identification

pattern

Even-parity bit

(for bits 1 to 31)

BCH(31, 21) generated check bits

Flag : "0" = Adderss signal

Function bits

Bits 2 to 19 (18 bits)

Bits 22 to 31 (10 bits)

P

Figure 2. Call number to call sign conversion

(2) Code words (address and message signals)