User Manual

PROGRAMMING
3-7
June 1997
Part No. 001-3492-001
4. For quickest lock times the SYNTH ENABLE line
on the last load word should be held high for 2 to 3
milliseconds. It MUST NOT be left high as the syn-
thesizer in the SPEEDUP mode has poor noise per-
formance and would degrade the Receive
performance.
Figure 3-9 TX TO RX TIMING DIAGRAM
Speedup is 2 to 3 ms
Lock is approximately 7 ms
Ramp is approximately 3 ms
Dekey is approximately 3 ms
"Ramp-Down" is the amount of time required for
the transmitter output power to be reduced before
switching off the transmitter and enabling the receiver
with the RX EN. The Ramp-Down circuitry (located
on the transceiver) minimizes adjacent channel inter-
ference caused by spectral spreading (sinx/x) when the
transmitter un un-keyed. The Ramp-Down time is
approximately 3 ms.
D0D24D0 D24 D0 D24
"D" WORD "B" WORD "A" WORD
DATA
CLOCK
t=0
RAMP-DOWN
SPEEDUP
RX_EN
SYNTH_EN
9V TX
TX_EN
"C" WORD