User Manual

PROGRAMMING
3-3
June 1997
Part No. 001-3492-001
NM3 = (INT(64 x FRAC [N ÷ 64]) ÷ 8) - 1
= (INT(64 x 0.59375) ÷ 8) - 1
= (INT(38 ÷ 8)) - 1
= 4 - 1
= 3
NM2 = 8 x FRAC [N ÷ 8]
= 8 x 0.75
= 6
NM1 = INTEGER [N ÷ 64] - NM2 - NM3 - 3
= 267 - 6 - 3 - 3
= 255
3.2.7 TX / RX FREQUENCY SHIFT AND BAND
SELECTION
As mentioned in 3.2.2, in order to implement the
band selection and Rx/Rx an additional 8 bits of data
are added to each of the synthesizer load words (D/C/
B/AO) (see Figure 3-1). The frequency bands and
Transmit/Receive Bits are defined as follows:
Low Band 928-944 MHz
High Band >944 MHz to 960 MHz
xx Don’t care
Low+ Low Band Select (1=lowband, 0=highband)
Low- Low Band Select (0=lowband, 1=highband)
Tx+ Transmit Select (1=Tx mode, 0=Rx mode)
Tx- Transmit Select (0=Tx mode, 1=Rx mode)
Figure 3-2 D-WORD
4
321 141312111098765 2019181715 16 24232221
1 1 1 1 1 1 1 1 00/110000000000000
ADDRESS
BITS
= 350 FOR 50 kHz REFERENCE
EA (ALWAYS 1)
FMOD (1 = MODULUS 8)
SA (ALWAYS 00)
EM (ALWAYS 1)
SM (ALWAYS 00)
LONG (0=24 BIT WORD)
NR (REFERENCE DIVIDE)