Hal Communications ST-6000, Инструкция по эксплуатации

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3-15
3.3.4 External Data Processing Equipment
Since both the pre- and post-autostart data signals as well as the inputs to the loop keyers are
available on the AUXILIARY connector, external data processing equipment can be connected be-
tween the ST-6000 demodulator and keyer circuits. This feature allows connection of such external
devices as the various popular UART devices, digital autostart, electronic stunt boxes, speed con-
verters, and so on. The external equipment should be compatible with the CMOS integrated cir-
cuits used in the ST-6000 and should include its own, separate power supply. The +12 Volt con-
nection on the AUXILIARY connector can be used for "reference" or "pull-up resistor" applications
ONLY. Be sure to use adequate shielding and RF by-passing to prevent the feed-back of spurious
RF energy into the ST-6000.
An external data processing device can be connected to the ST-6000, using either the uncondi-
tioned data (Pre-autostart Data) or autostart conditioned data (Post-autostart Data) as the device
input signal and then routing the device output signal back to the ST-6000 I/O driver circuits. ALL
ST-6000 external data and control circuits use CMOS compatible levels of 0 and approxi12
Volts. All data circuits have the convention of MARK = 0 Volts and SPACE = +12 Volts. Control cir-
cuits are labeled using positive-true logic conventions (thus, Remote Standby is in standby with 0
Volts applied and in receive with +12 Volts applied). The user may wish to make-up his own AUX-
ILIARY connector plug with the pins and shell provided rather than make extensive modifications
to the AUXILIARY jumper plug circuit board. A typical connection to a UART device is shown in Fig-
ure 3.7.
Obviously, a great many other I/O and control connections can be made. The user should thor-
oughly study section 5 and understand how the various sections of the ST-6000 operate and inter-
act before these connections are made.
3.3.5 External Oscilloscope Connections
The MARK and SPACE AC signals are available on the rear panel SCOPE connector. The signals
are approximately 2.0 Volts peak-to-peak amplitude into a recommended 100-kOhm minimum load
impedance. The MARK signal is available on pin 3, the SPACE on pin 1, and signal ground on pin 2.
3.3.6 Tone Keyer Control Connections
As noted in section 3.3.3, the ST-6000 tone keyer is normally connected for half-duplex opera-
tion when the AUXILIARY jumper plug is used. With this connection, the tone keyer is driven by
any data that keys the loop, whether it is received data or from keyboard (or TD) interruptions of
the loop. Under these conditions, the tone keyer output is ALWAYS present and repeats the input
to the demodulator when receiving. Thus the ST-6000 acts as a repeater, processing the data in
the demodulator and regenerating noise-free tones in the keyer sect ion. This is a particularly con-
venient feature if it is desired to record the signal on an audio recorder (for autostart recording, for
instance) or to repeat the signal on another communications link. (Use of the ST-6000 in a TTY re-
peater would be further enhanced if the received data is first coupled through a UART digital data
regeneration circuit before driving the tone keyer section.).
There are, however, instances when it is desirable to be able to separate the transmit and re-
ceive functions of the ST-6000 (as described in section 3.3.3) or turn-of f the tone keyer circuit ex-
ternally. The output of the tone keyer can be externally controlled with the TONE ENABLE signal,
available on pin 12 of the AUXILIARY connector. As indicated by the labeling, this is an inverted
control signal, 0 Volts = tone on and +12 Volts = tone off. As noted earlier, this control line should
be driven by CMOS compatible signals. If the tone output is only required during transmit, the KOS