MC145426 Motorola, MC145426 Datasheet - Page 15

• Manufacturer Part Number: MC145426
• Description: (MC145422 / MC145426) UNIVERSAL DIGITAL-LOOP TRANSCEIVER(UDLT)
• Manufacturer: Motorola

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DataSheet
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Differential–Phase–Shift Keying waveforms are shown in
Figures 12 thru 14. The DPSK encodes data as phase rever-
sals of a 256 kHz carrier. A 0 is indicated by a 180 phase
shift between bit boundaries, while the signal continues in
phase to indicate a 1. This method needs no additional bits
to indicate the start of the burst.
ceivers is a slightly modified form of DPSK, as shown in Fig-
ure 12. The phase–reversal cusps of the DPSK waveform
have been replaced by a 128 kHz half–cycle to lower the
MOTOROLA
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Both the Differential–Phase Shift Keying and the Modified
The modified DPSK waveform actually used in the trans-
13a. Bit Pattern — 1010101000
1
Figure 13. Typical Signal Waveforms at Demodulator
Figure 12. Modified Differential Phase Shift Keying
0
1
MODIFIED DIFFERENTIAL–PHASE–SHIFT KEYING
DIFFERENTIAL–PHASE–SHIFT KEYING
0
1
0
spectral content of the waveform, which, save for some key
differences, appears quite similar to frequency shift keying.
The burst always begins and ends with a half–cycle of
256 kHz, which helps locate bit boundaries.
form due to the even number of phase changes or zeros. The
waveform shown in Figure 13b shows random data patterns
being modulated.
26 AWG twisted–pair wire as viewed at LI of the master
UDLT and the slave UDLT.
The bit pattern shown in Figure 13a shows a stable wave-
Figure 14 shows the “ping–pong” signals on 3000 feet of
1
13b. Bit Pattern — Random
0
0
1
MC145422 MC145426
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