Table 6. Connector Descriptions
Connector
Use
REF OUT
Output terminal for an external reference signal for the LO on the
device. REF OUT is an SMA (f) connector with an impedance of
50 Ω, and it is a single-ended reference output. The output signal at
this connector is 10 MHz at 3.3 V.
REF IN
Input terminal for an external reference signal for the LO on the
device. REF IN is an SMA (f) connector with an impedance of 50 Ω,
and it is a single-ended reference input. REF IN accepts a 10 MHz
signal with a minimum input power of 0 dBm (0.632 V pk-pk) and a
maximum input power of 15 dBm (3.56 V pk-pk) for a square wave
or sine wave.
PPS TRIG OUT
Output terminal for the PPS timing reference. PPS TRIG OUT is an
SMA (f) connector with an impedance of 50 Ω and is a single-ended
input. The output signal is 0 V to 3.3 V TTL. You can also use this
port as a triggered output (TRIG OUT) that you program with the
PPS Trig Out I/O signal.
PPS TRIG IN
Input terminal for PPS timing reference. PPS TRIG IN is an SMA (f)
connector with an impedance of 50 Ω and is a single-ended input
channel. PPS TRIG IN accepts 0 V to 3.3 V TTL and 0 V to 5 V
TTL signals. You can also use this port as a triggered input
(TRIG IN) that you control using NI-USRP software.
GPS ANT
Input terminal for the GPS antenna signal. GPS ANT is an SMA (f)
connector with a maximum input power of -15 dBm and an output of
5 V DC to power an active antenna.
Notice
Do not terminate the GPS ANT port if you do
not use it.
PCIe x4
Port for a PCI Express Generation 2, x4 bus connection through an
MXI Express four-lane cable. Can be used to connect an external
USRP device or external chassis.
SYSTEM POWER IN Input that accepts a 15 V ± 5%, 10 A external DC power connector.
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USRP-2974 Getting Started Guide
