SPIRIT1 datasheet(50/94 Pages) STMICROELECTRONICS

50 / 94 page

Transmission and reception

SPIRIT1

50/94

Doc ID 022758 Rev 3

For fXO = 26 MHz

With this solution the maximum deviation for the 26 MHz case is limited to about 355 kHz,

but this is still acceptable since the maximum useful deviation is about 125 kHz (MSK @ 500

kbps).

In GFSK mode the Gaussian filter BT product can be set to 1 or 0.5 by the field BT_SEL of

the MOD0 register.

In MSK mode, the frequency deviation is automatically set to ¼ of the data rate and the

content of the FDEV register is ignored.

The calculation done inside the modem assumes that the digital clock is equal to the

synthesizer reference. Hence, in the 52-MHz case the MSK can actually be configured by

setting the frequency deviation to ¼ of the data rate through the FDEV registers as for

normal 2-FSK. The same is true for GMSK mode, which can be configured by setting the

frequency deviation to ¼ of the data rate through the FDEV registers as for normal GFSK

with Gaussian filter BT equal to 1 or 0.5.

OOK and ASK

If MOD_TYPE = 2 and power ramping is enabled, then ASK is used; otherwise, if

MOD_TYPE = 2 and power ramping is disabled, then OOK is used.

When OOK is selected, a bit '1' is transmitted with the power specified by

PA_POWER[PA_LEVEL_MAX_INDEX], a bit '0' is transmitted with the power specified by

PA_POWER[0](normally set to PA off).

When ASK is selected, a bit '1' is transmitted with a power ramp increasing from

PA_POWER[0] to PA_POWER[PA_LEVEL_MAX_INDEX], a bit '0' is transmitted with a

25390.6

28564.5

31738.3

34912.1

38085.9

41259.8

44433.6

47607.4

50781.3

57128.9

63476.6

69824.2

76171.9

82519.5

88867.2

95214.8

101562.5

114257.8

126953.1

139648.4

152343.8

165039.1

177734.4

190429.7

203125.0

228515.6

253906.3

279296.9

304687.5

330078.1

355468.8

380859.4

406250.0

457031.3

507812.5

558593.8

609375.0

660156.3

710937.5

761718.8

E/M

396.7

495.9

595.1

694.3

793.5

892.6

991.8

1091.0

1190.2

1289.4

1388.5

1487.7

1586.9

1785.3

1983.6

2182.0

2380.4

2578.7

2777.1

2975.5

3173.8

3570.6

3967.3

4364.0

4760.7

5157.5

5554.2

5950.9

6347.7

7141.1

7934.6

8728.0

9521.5

10314.9

11108.4

11901.9

12695.3

14282.2

15869.1

17456.1

19043.0

20629.9

22216.8

23803.7