The F-1611/U Radio Frequency Distribution Unit (RFDU) is designed to obtain a 'clean' signal spectrum to Cubic's receivers without the interference of nearby transmitters. This is particularly helpful when, for example, a high-power transmitter would otherwise interfere with a co-located receiver. The RFDU accomplishes its task by processing incoming radio signals, rejecting unwanted transmissions and directing wanted signals to as many as eight separate receivers at one time (customer supplied).  With eight fixed band-reject filters and four tunable notch filters, the HF signal spectrum (2 to 30 MHz) can be adjusted to remove many segments of unwanted signals. The tunable notch filters can also be 'stacked' to block out very close, overpowering transmissions. The RFDU can also be operated via the standard IEEE-488 interface and remotely controlled by computer. In addition, the RFDU reduces the number of antennas required for reception. Rather than one antenna for each receiver, the unit distributes the signal to all eight receivers from a single antenna.