Broadband Products, Inc.

The advent of digital video and cable modems has presented new challenges for manufacturers of drop passives. Cable operators are upgrading their plant and activating their return path in order to take advantage of these lucrative revenue opportunities.

Hum Modulation
Some two-way cable systems are finding the presence of hum modulation on their drops as a result of neutral fault currents that may exist on the outer shielding of drop cable. These currents sometimes saturate the ferrite cores found in drop splitters and directional couplers. When this happens, these ferrites can become magnetized resulting in hum modulation causing up to 40 percent packet loss, as well as other problems with data throughput and/or digital video.

Intermod Distortion
Another problem that has surfaced within two-way cable plant is intermod distortion. Under certain conditions, high-level reverse path signals passing through drop splitters or directional couplers can result in these products generating beats that interfere with forward path signals in the drop. This can be caused by a combination of high dB return path signal, such as that coming out of many cable modems, along with a splitter that carries residual magnetism in its ferrite cores.

Broadband Products has introduced three products that address these potential problems; our BDS1000, BDS2000 Series drop splitters; and our BDC1000 directional couplers.

These products utilize block capacitors on each leg to eliminate hum modulation as described in the first paragraph by blocking the neutral fault currents before they reach the ferrite cores. By using block capacitors on all output legs as well as the input leg, ferrites are protected from currents originating from either the subscribers home or from the outside plant; therefore, they cannot become saturated and cannot cause hum modulation.

To address intermod distortion, BPI incorporates the use of proprietary high quality ferrites. These ferrites feature robust permeability providing the cable operator with consistent performance over time. Another characteristic of high quality ferrites is High-Q Selectivity. We have incorporated complete intermod distortion data, using the SCTE established two frequency carrier test into our specification sheet.

Another improvement is the use of surface mount technology, or "SMT", in our printed circuit boards. SMT provide excellent grounding of the circuit at high frequencies. This superior ground improves return loss. SMT also allows us to use chip resistors and capacitors in the circuit thereby reducing stray inductances and capacitance.

An additional feature incorporated into many of our splitters and passives is flat port ends. Broadband Products was the first company to make this feature available and we remain one of only a few select companies that offer this important feature on a full range of drop passives, including ground blocks, F81's and wall plates. Flat port ends clearly are the best match for F connectors providing a flat mating surface that helps to protect against moisture and RF ingress/egress.

You can count on Broadband Products BDS / BSP / BDC / BRS Series drop passives for your advanced two-way digital network. Please see our specification sheets for more information.