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Front Panel
Connectors
Output
SYNC Output
TRIG/FSK IN
SINE OUT
1-8 Overview
The 3155 has 3 BNC connectors on its front panel: main and SYNC
outputs and trigger input. There are also 2 SMB connectors: sine
output and 10MHz reference input. These connectors are described
below.
The output connector outputs fixed (pre-defined) waveforms up to
50MHz, user (arbitrary) and sequenced waveforms with sampling
clock to 100MS/s. Output impedance is 50Ω; the cable connected to
this output should be terminated with 50Ω load. Amplitude accuracy
is calibrated when connected to a 50Ω load. The amplitude is dou-
bled when the output impedance is above 1MΩ.
The SYNC output generates a single TTL pulse for synchronizing
other instruments (i.e., an oscilloscope) to the output waveform. The
SYNC signal always appears at a fixed point relative to the wave-
form. The location of the SYNC signal along the waveform is pro-
grammable. The SYNC output is also used as a marker output when
the sweep or FM functions are turned on.
In general, this input accepts signals that stimulate generation of
output waveforms. The trigger input is inactive when the generator
operates in continuous mode. When placed in trigger, gated or burst
modes, the trigger input is made active and waits for the right condi-
tion to trigger the instrument. In trigger and burst modes, the trigger
input is edge sensitive, i.e., it senses transitions from high to low or
from low to high to trigger the 3155. The direction of the transition is
programmable. In gated mode, the trigger input is level sensitive,
i.e., the generator is gated on when the logic level is high and idle
when the level is logic low. Trigger level for this input is TTL.
The same input is used in FSK mode, where the output hops b e-
tween two frequencies – carrier and shifted frequencies. The output
generates carrier frequency when the FSK input is false and shifted
frequency when the FSK input is true.
The trigger input is also used as stop and start input when the 3155
is placed in Arm mode.
This SMB connector outputs DC coupled, fixed level (1V
50Ω) sine waveforms. This output is derived directly from the sample
clock generator and is active at all times, regardless of present oper-
ating mode of the 3155. The frequency of the sine output is pro-
grammed using the sample clock parameter. Frequency agility and
User Manual 3155
into
pk-pk
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