Satellite M2M
ORBCOMM operates a network of low Earth orbit (LEO) satellites that provide worldwide coverage. These satellites are relatively small in size,
weighing less than one hundred pounds and measuring only forty-two inches
in diameter and six inches in height before deployment. The relatively small
size of our satellites is made possible by the fact that they do not require
a propulsion system to maintain the satellites in the appropriate orbit and
have significantly lower power requirements as compared to geostationary
satellites.
Each satellite is equipped with a VHF and Ultra High Frequency, or UHF, communication
payload capable of operation in the 137.0-150.05 MHz and the 400.075-400.125
MHz bands. The use of the system uplink (Earth-to-space) spectrum is managed
by an on-board computer that employs the ORBCOMM-pioneered Dynamic Channel Activity
Assignment System, or DCAAS. DCAAS continuously scans the authorized spectrum,
identifies frequencies in use by other users of the frequency band and assigns
subscriber communication uplink channels to minimize interference. DCAAS changes
the uplink frequency at least every 15 seconds, which allows our system to coexist
with the current users of the VHF frequency band, and limits interference to
acceptable levels. The gateway earth stations and the subscriber communicators
communicate with the satellites in the same VHF band, thus eliminating the design
complexity, as well as the associated bulk, power and cost of supporting multiple
communication equipment on a single satellite. Our satellites also contain packet-routing
communications capability, including a limited store-and-forward capability.
Sun-Nadir Steered Configuration
- Vertical disk-shaped body with nadir-oriented quad helix antennas
- Single-axis, dual panel solar array deployed normal to body
Vital Statistics
- 92 pounds
- 41” diameter x 6.5” high (stowed configuration)
- 170” long x 88” high (antenna and solar array deployed)
Bus Subsystem
- Peak power tracking with GaAs solar array
- Wheel-augmented gravity gradient / magnetic 3-axis ACS
- GPS state vector determination
- Cold gas propellant / differential drag stationkeeping
- Central flight computer for data / command storage
For current element sets and LEOSphere configuration files, go here.