IBM F-Coupler
Broadband and baseband LAN US 4885747 A  Original IBM F-Coupler
Electrical connector US 5293298 A   Improved IBM F-Coupler

F-Coupler Planning Guide (GA27-3949)
F-Coupler Assembly and Installation Instructions (GA27-3950)

Baseband signals may be identified as the cable ICS (IBM Cabling System) or the actual network, such as "Token Ring" or "PC Network".
Broadband is VHF

F-Coupler and Faceplate  

Original F-Coupler
F-Coupler Figure 1

FIG. 1 shows a schematic of the improved communications system according to the teachings of the present invention.

Figure 2

FIG. 2 shows a distribution link in the communications system and an electrical schematic of one embodiment of the F-coupler.

Figure 3
FIG. 3 shows a schematic of the signaling spectrum for different types of signals that are transmitted on the improved communications system of FIG. 1.

FIG. 3 shows a graphic representation of the signal spectrum and the allocation for data signals which are transmitted in the baseband frequency range and VHF signals which are transmitted in the broadband frequency range. The graph is helpful in understanding the relationship between signals that are simultaneously on the common lobe assembly means which interconnects the wiring closet to the office (FIG. 1). In FIG. 3, frequency is plotted on the horizontal axis and amplitude is plotted on the ordinate or vertical axis. The frequency range which transmits data for baseband machines is identified on the graph as ICS data. Information for the PC Network stations and other machines is transmitted at a transmit frequency identified in FIG. 3 as PC Network Data Transmit and is received at a higher frequency identified as PC Network Data Receive. The frequency range used by the high frequency devices is identified as VHF TV (Very High Frequency Television) and VHF, respectively. These may be typical CATV (Cable Television) signals following the NCTA (National Cable Television Association) standards for bandwidth, frequency allocation and signal amplitudes.

Improved F-Coupler