MA1916

3/11

CONVOLUTION ENCODER

The convolution encoder generates 2 serial bits of output

data for each bit it reads in. The coding operates cyclically over

a length of 7 bits. It increases the bandwidth of the signal but

establishes a correlation between succesive bits in the output

signal.

The convolution encoder operates continuously using

CE_CLK to read data in on CE_IN and to write the encoded

data to CE_OUT.

If required the output of the Reed-Solomon encoder can be

fed directly into the convolution encoder by connecting

RSE_OUT to CE_ IN and CLKS to CE_CLK.

TEST GENERATOR

The MA1916 contains its own built-in test pattern

generator, this can be connected to the RS encoder for in

service testing. The test generator supplies test patterns and

the SMC signal according to the inputs on T0-2 (see Table 2)

and the interleave depth selected using SEL_A and SEL_B.

Figure 3 shows the necessary connections for feeding test

patterns through both the RS and the convolution encoder.

Figure 3: Test Configuration

Table 2: Test Pattern on MSG_OUT Defined by T0-2

PIN DESCRIPTION

The MA1916 uses a single power supply of 5V

±10%.

CLK (Clock)

This input supplies a clock signal to the RS encoder and

the Test generator. It requires a signal with a nominal 50%

duty cycle running at twice the input data rate for the RS

encoder. The rising edge of CLK is used to generate the

internal CLKS signal which clocks data through the RS

encoder.

n_RST (Reset)

This active low signal is a reset supplied to the RS encoder,

the test generator and the convolution encoder. It should be

noted that the reset does not clear the check sum in the RS

encoder and a complete dummy data packet should be run

through before valid data is sent.

SEL_A and SEL_B (Interleave Depth Select)

These inputs define the interleave depth of a message

passing through the RS encoder They also specify the

message length to be produced by the test generator (see

Table 1). The inputs are connected to internal pulldown

resistors.

These inputs select the pattern to be produced by the test

generator (see Table 2). Each input is connected to an internal

pull-down resistor.

This input is used for production testing only It has an

internal pull-down resistor and should be left unconnected .

MSG_OUT (Test Message Output)

This output pin carries the test patterns defined by the

inputs To-2 and produced by the test generator. This signal

can be connected directly to MSG for testing purposes.

Interleave Depth

T2

T1

T0

Test

I = 5 (1115 bytes)

I = 4 (892 bytes)

I = 1 (223 bytes)

000

N/A

0

0

0

1

1

(1, 2, 3, 4, 5) x 223

(1, 2, 3, 4) x 223

(1) x 223

0

1

0

2

(0) x 222 x 5, (0) x 4, (7B)

(0) x 222 x 4, (0) x 3, (7B)

(0) x 222, 7B

0

1

1

3

(0) x 222 x 5, (7B, AF, 99, FA, B7)

(0) x 222 x4, (7B, AF, 99, FA)

(0) x 222, 7B

1

0

0

4

(0) x 221 x 5, (7B) x 5, (47) x 5

(0) x 221 x 4, (7B) x 4, (47) x 4

(0) x 222, 7B

Other

N/A