Site: Nippon Electric Corporation (NEC)
4035 Ikebe-ch o, Midori-ku
Yokohama 226, Japan
Date Visited: October 20, 1992
Report Author: W. Brandon
J. Pel ton
Dr. Susumu Kitazume
Dr. K. Yamamoto
NEC is a giant in the world of electronics, with annual sales of $22.9 billion and capital of $1.4 billion. Established in 1899, it now consists of eight major divisions, 28 manufacturing subdivisions, 34 software s ubsidiaries, and 29 overseas plants in 15 countries. Of over 100,000 total employees, about 3,300 staff the Yokohama plant, established in 1969 for the manufacture of radio telecommunications equipment, including satellite, microwave, network, and mobile systems. NEC aggregates its business into three major categories: semiconductors, computers and radio communications. NEC's world rank and approximate sales in these categories are shown in Table NEC.1.
NEC's World Rank and Approximate Sales
NEC products are in the forefront of integration of communications and computers (C&C), implementing the corporate vision of "one world through C&am p;C." Terrestrial microwave systems in nearly every country, cordless telephones, the miniature paging receiver, VSATs, and satellite transponders are important examples.
In the field of satellite communications, NEC is a major world supplier of earth stations, as well as satellite components (and satellites with its overseas partners, GE and Hughes). NEC has captured 58 percent of the market for INTELSAT Standard A stations in the past five years and has a 35 percent cumulative share. Approxi mately 42,000 VSATs have been sold, a significant fraction of the world total.
NEC has been prime contractor for 33 major national space programs already completed (compared with fourteen for MELCO and four for Toshiba), with significant involvement since 1969. Table NEC.2 lists current programs (in development); notes on these and prior programs indicate the breadth of NEC space activity.
Gbits/sec Network. Demand for Gbits/sec rate computer interconnection is anticipated, including remote access to databases. The highest data rate currently used in satellite communications i s 300 Mbits/sec.
Multi-media Communications. This is to be implemented in the JEM-to-ground link for fax, video, write on-board.
HDTV. Analog transmission via BS-3b will use 27 MHz bandwidth employing the MUSE technique to reduce ba ndwidth; the digital transmission rate will be 70 Mbits/sec. The goal is to reduce requirements to 40 to 45 Mbits/sec for DBS, possibly for BS-4. Experimental "Hi-Vision" broadcast tests are now under way by NHK on BS-3b. Hi-Vision home telev ision sets are now on sale.
Mobile Services. ETS-V (launched 1986) was the first satellite offering aero mobile satellite service. N-STAR will introduce S-band (2.5 GHz) for mobile communications. NEC expects high demand but is not pursuing an IRIDIUM-like approach. They anticipate that LEO satellites used for E-mail will succeed. The concern for all PCS systems is interference. NEC asked about the relative merits of TDMA versus CDMA for interference control.
Ta ble NEC.2
Current NEC Programs
RDSS. GPSS receivers are low cost and supplied by several Japanese manufacturers. AUSSAT B provides RDSS. NEC does not anticipate new systems in RDSS.
ISL s are under development and study. Since spatial acquisition is critical, a scheme involving a sequence of wide, medium, and finally narrow beamwidths is being studied for laser crosslink acquisition. Space station to GEO (GEO to LEO) equipment is at th e breadboard stage (20 dBm, solid state, 0.8 mm, with fine pointing by piezo-electric control) (Shiratama 1990). RF ISLs are being developed for COMETS (S- and Ka-band). Radiation hardened, but not space-qualified, parts are being considered for high re liability.
MMICs. 1 GHz (switch module) and 4 GHz (L.O.) MMICs are used in N-STAR (NTT-developed).
TWTs. A 120 W, 11.7 to 12.2 GHz TWT, massing 3.5 kg, radiation-cooled, using PPM focusing, operating with 46% efficiency, has been produced. Figure NEC.1 is an overview of NEC's TWTAs and SSPAs.
Figure NEC.1. NEC SSPAs and TWTAs
H igh Temperature Superconductors. Oscillators and filters are being studied but no developments have been initiated.
In the future, NEC will need to interface ISLs (GEO to GEO, and GEO to LEO) with uplinks and downlinks through OBP. Each has been investigated separately. Processing is not recommended for ISL to DL. NEC has not investigated world-wide mesh networks via satellite.
On-Board Computer. The NEC computer group provides on-board computer support to the Space Systems Development Division. An NEC on-board computer display was used for attitude control on MUSES-A. Its parameters were 25 MIPS; 64 kbytes RAM; 32 kbytes ROM; 7 W power consumption; 2.5 kg mass; dimensions 220 x 200 x 100 mm; operating temperature range -20 degrees centigrade to +50 degrees centigrade. NEC anticipates requirements for large memory and buffering and has developed a space-qualified 64 kbit SRAM.
On-Board Switching. NEC is developing several kinds of microwav e switch matrices (MSMs) for ETS-VI and N-STAR. They have a 4 GHz 8 x 8 MSM.
NEC has developed a 16 x 6 MMIC-based decoder and controller, operating at 30 Mbits/sec per channel, under INTELSAT contract IS 321 for the INTELSAT VI R&D program.
NEC has developed a 4 x 4 switch processor with rate changing (adaptation). NEC wanted to develop a 20 x 20 switch for INTELSAT VIII but this was not required. They expect to develop the 20 x 20 MSM for INTELSAT IX.
NEC and SCR are jointly developin g a breadboard model of a 3000 x 3000, 64 kbits/sec switch for compatibility with ISDN (but not with ISDN protocols). The separate access control channel will use the slotted Aloha protocol. The on-board controller will perform demand processing. Contr ol will be implemented using SCPC on the uplink and TDM on the downlink. NEC has developed a 64 x 1000 switch in LSIC, which they intend to expand for the 3000 x 3000 version. A large on-board memory is not required due to use of the SCPC/TDMA approach.
On-Board-Switching Protocols. NEC is working on both LANs and WANs. LANs being designed for the space station network will use the IEEE 802.4 and token bus protocols. Also, IEEE 1553b protocols will be employed for on-board switching units .
Solar Cells. Si solar cells produced by Sharp and GaAs cells produced by MELCO are used by NEC in their bus power generation systems.
Structures/Materials. Viscous damping materials, control of space structure vibration using the piezo-electric effect, and a compressible truss (triangular cross section) using sliding struts are being developed.
Thermal Control. Various types of coolers are under development, including a Peltier co oler, a 20 degree K cryo-cooler, and a 2 degree K He superfluid (He loop) cooler (Tanaka 1987).
TT&C. Devices being developed for TT&C applications include a 4 Megabit RAM, CMOS ROMs, EEPROMs, a single-chip 16 or 32 bit MPU including peripheral circuits, and a large scale (100 K gates) gate array.
NEC has developed a major world role in satellite communications through its success in the Japanese market as a prime contractor and in worldwide systems, as supplier o f transponders and other payload subsystems and components for satellites, and a supplier of earth stations in all sizes. Its many products in cellular and mobile telephone systems and world leadership in semiconductors, computers and communications plac e NEC in a unique position astride these major technology streams whose confluence lies ahead in the next century. Participation in national programs and strategic partnerships add further strength. Investment policy is to spend 6% of sales on research and development. NEC's president, Tadahiro Sekimoto, has a deep interest in satellite communications in part due to his background at COMSAT Corporation. Thus, NEC may be expected to lead in the implementation of its corporate vision of the "one wo rld through C&C" concept, the integration of computers and communications for the benefit of society.
Figure NEC.2. NEC Receivers
Figure NEC.3. NEC Upconverters and Receivers/Downconverters