Operating Considerations
The LTX-551X system may be used to transmit signals from a source that is distant or at a different
ground potential with respect to measuring devices such as an oscilloscope. The input signal must
be in the range of 0 - ± 1 V or 0 - ± 5 V depending on the range selected. Digital signals may be
transmitted as well. TTL, CMOS or LVTTL level signals are acceptable. The output signals are LVTTL
( 0-3.3 V).
For high speed signals transmitted via any significant amount (electrical length comparable to rise/fall
times) of coaxial cable, a 50 ohm termination may be switched in to preclude distortion and reflections
from a mismatched transmission line.
The power supply for the unit must be at roughly the same potential of the signal common mode
voltage. For example, using the unit at a 10 000 V potential while it is utilizing the wall mount power
supply at conventional line potential will result in a
hazardous situation and certain damage to the
equipment
.
An isolation transformer with sufficient isolation voltage rating must be used to power the
wall mount supply.
The length of fiber optic cable that may be used with the LTX5510 is typically 300 M for 62.5/125um
fiber or 500 M for 50/125um fiber and for the LTX5515 the typical distance is 150M for 62.1/125um
fiber and 300 M for 50/125um fiber. Fiber bandwidth and not loss is typically the limiting factor for
range with multimode units. The single mode version is limited by loss. Typical ranges of 10 km may
be achieved with this model using single mode fiber.
When setting up the LTX-551X system,
note that the transmitter must be turned on last!
This
allows the receiver to detect the synchronizing framing characters. Meaningless signals will otherwise
be generated. Should sync be lost by disconnecting the optical fiber, simply turn the transmitter off
and on.
The red LED labeled O.L. indicates that the input signal exceeds the maximum input voltage for the
range in use.
The green LED on the receiver indicates that the receiver is operating with an adequate optical input
signal. If the indicator goes out, the transmitter has lost power or the connecting fiber is disconnected
or broken.
The controls and their functions are indicated on the following pages.
The output signal from the receiver has a 10 V peak to peak output into an open circuit. The
maximum output into a fifty ohm load is 4 V peak to peak.
DIGITAL INPUT/OUTPUT
CONNECTIONS
Digital Ground
Chan. 5
Chan. 2
Chan. 3
Chan. 4
5
3
4
2
1
4