Network test instrument with cable connection and signature testing

A test instrument method comprising:

• transmitting a reflectometry pulse from a port of the test instrument;
• receiving a reflected pulse on the port in response to transmitting the reflectometry pulse from the port;
• measuring characteristics of the reflected pulse received via the port, wherein the reflected pulse is the reflectometry pulse reflected from an impedance in a system connected to the port;
• and
• determining whether the port is connected to a minimum length cable based on the measured characteristics.

A test instrument comprising:

• a port connectable to a cable;
• a signal generator to output a reflectometry pulse to the port;
• a measurement circuit to measure characteristics of signals received via the port;
• and
• a processing circuit configured to:
• determine whether the port is connected to a minimum length cable based on characteristics of a reflected pulse received at the port and measured by the measurement circuit, and
• in response to determining the port is connected to the minimum length cable, determine whether a signature determined from the measured characteristics of the reflected pulse matches a stored signature to determine whether the test instrument is connected at a predetermined test location.