How it works
The enhanced Broadcast Power Monitor (BPM-E) is an instrument that is inserted directly into a transmission line to monitor the forward power, reflected power, and VSWR of the system. The BPM-E consists of a line section with forward and reflected directional couplers and an additional housing that contains the external circuitry. The external circuitry consists of a detector circuit and a control circuit.
The directional couplers sample, through a known coupling factor, the forward and reflected wave in the transmission line. The coupled RF signal is passed to the detector board and converted into a DC voltage. The DC voltage, which is proportional to the RF power in the line section, is then sent to the control circuit.
In the control circuit, an analog-to-digital converter digitizes the incoming signal and passes it to a microcontroller that manages input and output processing. The control circuitry communicates by sending signals to the alarm and power LEDs, receiving a user-initiated signal from the reset button, and both sending and receiving signals via the RS-232 connector (DB9), the Ethernet connector (RJ45), and the power/alarm connector (DB15).