Watkins-Johnson Company WJ-8718-19/FE Instruction Manual page 77

INSTALLATION AND OPERATION WJ-8718-19/FE HF RECEIVER '
2.4.9 REMOTE OPERATION VIA SYNCHRONOUS SERIAL I/O '
The Synchronous Serial I/O Option .permits full control of receiver '
parameters by an external controller. To establish remote operation the operator
must depress the front panel REMOTE keypad.
The Synchronous Serial I/O (SS I/O) allows the following six interface I
operations: i
i
1. Transfer To Receiver (TTR) i
2. Transfer From Receiver (TFR)
3. SIGNAL SEEK: SLEW UP r
4. SIGNAL SEEK: SLEW DOWN
5. COUNT PULSES: SLEW UP
6. COUNT PULSES: SLEW DOWN
TFR is the only interface operation that can be performed with the
receiver in REMOTE or LOCAL mode. The other interface operations are performed I
only when the receiver is in REMOTE mode. !
The SS I/O has two status outputs. The Receiver Remote Mode (RRM)
output is active high whenever the receiver is in REMOTE mode. The SQUELCH OUT
output is active high whenever the strength of the received signal is equal to or
greater than the operator programmed threshold during a SLEW interface operation.
2.4.9.1 Transfer to Receiver (TTR) and Transfer from Receiver (TFR)
Data format and the timing necessary for TTR and TFR operations are
shown in Figures 2-6 through 2-8. Note that parity is always odd for the 32 bit
message and that the receiver must be in REMOTE mode (RRM active high) for the
TTR operation.
2.4.9.2 Signal Seek: Slew Up and Signal Seek: Slew Down
The SIGNAL SEEK: SLEW UP or SIGNAL SEEK: SLEW DOWN operations
cause the receiver to step up or down in frequency steps equal to the current IF
bandwidth, and at a rate of 100 msec, per step. At each step the signal strength is
compared to the current threshold. If it is equal to or greater than the threshold the
SQUELCH OUT line is made active high. The remote controller then has 2 msec, to
lower either the SLEW UP or SLEW DOWN line before the receiver slews to the
current frequency plus or minus the IF bandwidth.
Once the receiver tuned frequency reaches 99.99999 MHz or 00.00000 MHz,
the operation will stop. There is no "wrap-around" in any of the remote SLEW
modes. Figure 2-9 shows the timing relationships for the SIGNAL SEEK: SLEW UP
operation.
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