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2003 News Release
January 27 
January 27, 2003
Hitachi Metals Develops World's First Ferrite Materials to
Substantially Reduce "Ingress Noise"
Ideal for Use in CATV Network Facilitated Broadband Internet
Access
Hitachi Metals, Ltd. announced today that it has developed and is now prepared to mass-produce a Ni-Zn ferrite material that markedly reduces transformer noise. These new ferrite materials (ND, NM series) keep ingress noise*1 to a minimum level when used as transformer cores of "couplers" and "distributors" in bi-directional CATV*2 systems that offer broadband Internet access. They are the world's first materials of their kind.
Ni-Zn ferrite material that markedly reduces transformer noise
1. Background
As the information and telecommunication field becomes increasingly multimedia-oriented, the demand for broadband Internet access, which enables the high-speed transmission of a large volume of information, is rising. Along with this trend, the expansion of CATV to include broadband Internet access and use as a telephone line in addition to traditional TV broadcasting has led to a jump in CATV subscriptions as well as attracting attention to the interactive media.In an interactive CATV system, there are "downstream signals" that run from a center office to many terminals and "upstream signals" that run from the terminals to the center office. In CATV systems, a large number of "couplers*3" and "distributors*4" branch off and distribute these signals. When upstream signals are transmitted to the center office, there is an extraordinary increase in background noise at the center office, which causes data errors and other problems. This noise stems from components used in subscriber's terminals, lines, etc. and it converges at one side of the center office. The total sum of this background noise is called "ingress noise" and there are two principal causes for this noise.
- Externally induced noise arising from electro-static and electromagnetic interactions
- nternal noise arising from the actual parts being used
2. Development History
Hitachi Metals' exploration in to the noise reduction revealed that "couplers" and "distributors" emit a substantial amount of noise. Furthermore, we ascertained that this noise was caused by the magnetostrictive property of Ni-Zn ferrite material being used as a transformer core. We performed a detailed composition analysis of the material and our efforts paid off--we succeeded in attaining a noise level that was up to less than 1/300 of previous levels. There have been no previous reports of the development of similar material---- it is the world's first material of its kind.
Hitachi Metals has developed two types of materials-ND50S and NM13D---to meet the different initial permeability requirements of "couplers" and "distributors".
Hitachi Metals intends to mass-produce the materials at both its Tottori Works and Panyu Works (China) and is prepared to meet the needs of its customers flexibly.
3. Features
This newly developed ferrite material will keep data errors and other problems arising at CATV centers to an absolute minimum by substantially reducing "ingress noise".1) Reduces the noise level up to 1/300 that of previous levels attained with Hitachi Metals' materials
2) "Couplers"---high initial permeability and low temperature coefficient
"Distributors"---low temperature coefficient
4. Applications
Primarily for use as transformer cores of "couplers" and "distributors" in bi-directional CATV systems.5. Patents
One patent pending in Japan and one patent being prepared to file overseas6. Manufacture and Sales
Manufacture: Tottori Works, Panyu Works (China)Sales: Information system components company (Tokyo)
Inquiries:
| Product Inquiries: | Mr. Shigeru Takeda Tel: +81-3-5765-4425 Fax: +81-3-5765-8319 |
|
| Press Inquiries: | Public Relations Office Mr. Shinji Kobayashi Tel:+81-3-5765-4079 Fax: +81-3-5765-8312 |
Terms & definitions
*1 Ingress noise
In bi-directional CATV systems, there is an extraordinary increase in noise when upstream signals are transmitted to the center office. The total sum of this noise at the center office is called ingress noise.
*2 CATV
Acronym for Community Antenna Television or Cable Television.
*3 Coupler
A transformer that subdivides a portion of mainline signals to branch lines. Approximately 1/9 to 1/16 of mainline signals are diverged.
*4 Distributor
A transformer that bisects a branch line signal. These transformers are combined to form 4-way, 8-way, and 16-way transformers.
*5 Magnetostriction
The phenomenon wherein the magnetization of magnetic materials such as soft ferrite core results in the deformation of its mechanical dimensions. In positive magnetostriction, the material stretches along the direction of the magnetic field, and in negative magnetostriction, the material shrinks in the direction of the magnetic field.
*6 Initial permeability
A constant that indicates the ease with which a magnetic material may be magnetized. The larger
the
smaller and higher performance the transformer attained from the
material.*7 Temperature coefficient
The value obtained by dividing the differential ratio of
by
the temperature difference as shown below;
