Half Duplex GMSK Modem

FX579

© 1996 Consumer Microcircuits Limited

21

D/579/4

Characteristic

Note

Min.

Typ.

Max.

Units

Transmit Parameters

TXOP output impedance

3

-

100

-

Ω

TXOP output level

4, 6, 9

0.8

1.0

1.2

Vpk-pk

-

-100

-

+100

mV

Tx data delay (BT = 0.3)

5

-

2.0

2.5

bit periods

Tx data delay (BT = 0.5)

5

-

1.5

2.0

bit periods

Receive Parameters

RXIN input impedance

3

-

M

Ω

RXIN input level

7, 9

0.7

1.0

1.3

Vpk-pk

9

-

±0.5

-

V

Rx time delay

8

-

-

3

bit periods

On-Chip Xtal Oscillator

Input impedance

10

10

-

M

Ω

Output impedance

10

-

50

-

k

Ω

Voltage gain

10

-

25

-

dB

"High" clock pulse width

11

60

-

-

ns

"Low" clock pulse width

11

60

-

-

ns

Notes:

1.

Not including any current drawn from the modem pins by external circuitry

2.

3.

Measured by ac coupling an external 1kHz source via suitable resistance to the TXOP pin.

The value specified is the average of values measured in the all "1"s and all "0"s states

4.

Data pattern of "1111000011110000..."

5.

Measured between the rising edge of the Tx DATACLK and the centre of the corresponding bit

at the output of the external RC network connected to TXOP

6.

Measured at the output of the external RC network

7.

For optimum performance, measured at RXIN for a "1111000011110000..." pattern

8.

Measured between the centre of bit at RXIN and corresponding rising edge of the

Rx data clock

9.

10.

Small signal measurement at 100Hz with no load on XTALN output

11.

Timing for an external clock input to the XTAL/CLK pin