ORBCOMM

NEWS

Introduction
Orbcomm Generation 2
Orbcomm Updates
Additional satellites in orbit
Tracking
Uplink frequencies
Downlink frequencies
Magellan GSC 100
Launch information

LINKS

Orbcomm corporate website

Return to Decode Systems home

ORBCOMM
Orbcomm is a constellation of low earth orbiting satellites providing two-way data and positioning service to small, portable user terminals in the VHF and UHF frequency bands.

ORBCOMM GENERATION 2
Orbcomm is in the process of deploying 18 second generation (OG2) satellites, built by Sierra Nevada Corporation. The first satellite was lost on October 10, 2012, three days after launch. The remaining 17 satellites will be launched via two SpaceX Falcon 9 rocket missions, inserting the satellites into four orbital planes of 52° 47° inclination, with three planes having four OG2 vehicles and a fourth plane with five. The satellites will orbit at an altitude of 750 715 kilometers.

ORBCOMM UPDATES
  • On December 21, 2015, Orbcomm launched 11 OG2 satellites from a SpaceX Falcon 9 rocket. OG2 spacecraft include Automatic Identification System (AIS) receivers, allowing vessel monitoring in near real-time. A total of 16 ground stations support 18 AIS-enabled satellites.

  • Orbcomm launched 6 OG2 satellites in 2014.

  • As of February 4, 2009, Orbcomm is reporting that the following satellites are operational: A1 - A8, B1 - B4, B6 - B8, C1 - C5, C7, D2 - D3, D6 - D8, G2.

  • As of December 31, 2008, Orbcomm reports 460,000 subscribers, a 31% increase over year-end 2007.

  • In May 2008 Orbcomm signed an agreement with Sierra Nevada Corporation to design and build 18 new satellites.

  • F2 was retired from service in April 2007 after experiencing intermittent failures. It was launched in 1995.

  • As of August 15, 2001, Orbcomm is reporting that the following satellites are operational: A1 - A8, B1 - B8, C1 - C5, C7, D2 - D4, D6 - D8, F2, G2.

  • In April 2001, a group of Orbcomm licensees bought all of the business and assets of Orbcomm, which had been under Chapter 11 protection since September 2000.

AUTOMATIC IDENTIFICATION SIGNALS
AIS-equipped Orbcomm satellites are capable of receiving signals between 161 and 163 MHz. Initially they will receive maritime AIS transmissions on 161.975 MHz (Channel 87B) and 162.025 MHz (Channel 88B).

Under a demonstration contract with the U.S. Coast Guard, AIS data will be received by the satellite and sent back down in the feederlink.

ADDITIONAL SATELLITES IN ORBIT
Orbcomm launched six satellites into orbit on June 19, 2008, from Kapustin Yar, Russia. These satellites are equipped with Automatic Identification System (AIS) payloads.

Orbcomm launched seven satellites into orbit on December 4, 1999, bringing the constellation total to 35.

TRACKING
Orbcomm is now publishing TLE's (two-line elements) on their webpage. A very enlightened and friendly attitude that should be duplicated by other satellite companies.

Click here to jump to their network data page.

A great tracking program to use with those elements is "Orbcomm View" from Northern Lights Software.

UPLINK FREQUENCIES
Subscriber terminals transmit data at 2400 baud up to Orbcomm spacecraft. FCC frequency allocations are as follows:

Lower Limit Upper Limit
148.000 148.250
148.750 148.885
148.905 149.585
149.635 149.900

Uplink power of 5W, frequencies between 148 and 150.05 (189 channels), at 2400 bps.

Ground stations transmit feederlink information to the satellites on 149.610 MHz and 150.025 MHz at 57.6 kbps. The signal is approximately 50 kHz wide.

DOWNLINK FREQUENCIES
Orbcomm satellites transmit to subscriber terminals at 4800 baud using symmetric differential phase shift keying (SDPSK) modulation. (SDPSK indicates a zero bit with a negative 90° phase shift and a one bit with a positive 90° phase shift.) The phase shifts are filtered via a 0.4 root-raised cosine (RRC) filter.

Information bits are differentially encoded (each bit is exclusive-ORed with the previous bit) in a Non-Return to Zero Mark (NRZ-M).

The spacecraft can vary the downlink power from 10 to 40 Watts. EIRP is about 12 dBW. Transmissions are right-hand circularly polarized (RHCP).

Downlink sensitivity of -118 dBm with a bit error rate of 10-5, frequencies between 137 and 138 MHz (399 channels), at 4800 bps.

Here are the frequencies allocated by the FCC for Orbcomm satellite downlinks:

Segment Lower Limit Upper Limit Bandwidth
1 137.1750 MHz 137.3275 MHz 152.5 kHz
2 137.4225 MHz 137.4725 MHz 50 kHz
3 137.6500 MHz 137.7500 MHz 100 kHz
4 137.7875 137.8125 25 kHz

Feederlink data is transmitted by the satellite on 137.560 MHz at 57.6 kbps.

Orbcomm spacecraft also transmit a UHF beacon (unmodulated carrier) at 400.1 MHz via a one watt transmitter and a small RHCP antenna.

Active subscriber downlink frequencies are:

137.2250
137.2500
137.4400
137.4600
137.6625
137.6875
137.7175
137.7375
137.8000

Individual satellite frequency assignments are as follows:

Spacecraft Orbcomm
Designator
Catalog Orbital
Plane
Launch Date Status Frequency Hearsat Freq
FM 1 F1 23545 F 3 Apr 95 Off 137.4600 137.4600
FM 2 F2 23546 F 3 Apr 95 Operational 137.4600 137.4600
FM 3 G1 25158 G 10 Feb 98 Operational 137.678 137.6875
FM 4 G2 25159 G 10 Feb 98 Operational 137.678 137.6875
FM 5 A1 25117 A 23 Dec 97 Operational 137.2000 137.7175
FM 6 A2 25118 A 23 Dec 97 Operational 137.2250 137.7175
FM 7 A3 25119 A 23 Dec 97 Testing 137.662 137.4400
FM 8 A4 25112 A 23 Dec 97 Operational 137.717 137.7175
FM 9 A5 25116 A 23 Dec 97 Operational 137.717 137.7175
FM 10 A6 25113 A 23 Dec 97 Operational 137.717 137.7175
FM 11 A7 25114 A 23 Dec 97 Operational 137.662 137.4400
FM 12 A8 25115 A 23 Dec 97 Operational 137.662 137.6625
FM 13 B1 25413 B 2 Aug 98 Operational 137.7375
137.8000
137.8000
FM 14 B2 25414 B 2 Aug 98 Operational 137.7375
137.8000
137.7375
FM 15 B3 25415 B 2 Aug 98 Operational 137.7375
137.8000
137.7375
FM 16 B4 25416 B 2 Aug 98 Operational 137.7375
137.8000
137.8000
FM 17 B5 25420 B 2 Aug 98 Operational 137.7375
137.8000
137.8000
FM 18 B6 25419 B 2 Aug 98 Operational 137.7375
137.8000
137.7375
FM 19 B7 25418 B 2 Aug 98 Operational 137.7375
137.8000
137.7375
FM 20 B8 25417 B 2 Aug 98 Operational 137.7375
137.8000
137.7375
FM 21 C1 25475 C 23 Sep 98 Operational 137.2500
137.2250
137.2500
FM 22 C2 25476 C 23 Sep 98 Operational 137.2500
137.2250
137.2500
FM 23 C3 25477 C 23 Sep 98 Operational 137.2500
137.2250
137.6625
FM 24 C4 25478 C 23 Sep 98 Operational 137.2500
137.2250
137.2500
FM 25 C5 25479 C 23 Sep 98 Operational 137.2500
137.2250
137.2500
FM 26 C6 25480 C 23 Sep 98 Operational 137.2500
137.2250
137.6625
FM 27 C7 25481 C 23 Sep 98 Operational 137.2500
137.2250
137.2500
FM 28 C8 25482 C 23 Sep 98 Operational 137.2500
137.2250
137.6625
FM 30 D2 25980 D 9 Dec 99 Operational
FM 31 D3 25981 D 9 Dec 99 Operational
FM 32 D4 25982 D 9 Dec 99 Operational
FM 33 D5 25983 D 9 Dec 99 Not Available
FM 34 D6 25986 D 9 Dec 99 Operational
FM 35 D7 25985 D 9 Dec 99 Operational
FM 36 D8 25984 D 9 Dec 99 Operational

The frequencies noted as "Hearsat" are derived from two-line element (TLE) data available at the Hearsat website operated by John David Corby.

Data on the downlink is packetized and contains user data as well as satellite position and velocity information derived every four seconds from the on-board Rockwell MPE-II GPS receiver.

Data words are 8 bits, with the LSB transmitted first. A minor frame is one second long, containing 4800 bits (600 words). A major frame is 16 minor frames.

MAGELLAN GSC 100
The GSC-100 provides handheld, two-way, electronic mail text messaging capability via Orbcomm. It also contains an integrated Magellan Global Positioning System (GPS) receiver.

The GSC-100 measures 8" (h) x 3.5" (w) x 1.75" (d) and weighs 37 ounces. The waterproof transceiver can be used as a hand-held terminal, operating on its rechargeable NiCad battery pack, or it can be bracket-mounted and operated by a 10-35 VDC external power source.

Discontinued in December 2001.

LAUNCHES
As of December 4, 1999, Orbcomm had launched 35 satellites. Not all of them work.

The FCC has authorized Orbcomm to launch a total of 48 satellites, but plans for the remaining 13 are not finalized.

  • Orbital Science's Stargazer Lockheed L-1011 aircraft launched a Pegasus rocket containing seven Orbcomm satellites midday Saturday, December 4, 1999, about 50 miles offshore from the Wallops Island facility in Virginia.
  • Orbital Science's Stargazer Lockheed L-1011 aircraft launched a Pegasus rocket containing eight Orbcomm satellites early Wednesday morning, September 23, 1998, about 50 miles offshore from the Wallops Island facility in Virginia.
  • Orbital Science's Stargazer Lockheed L-1011 aircraft launched a Pegasus rocket containing eight Orbcomm satellites on Sunday, August 2, 1998, offshore from the Wallops Island facility in Virginia. The eight satelllites were placed into a 820 km x 823 km circular orbit at a 45 degree inclination.
  • Hitching a ride with a US Navy GEOSAT Follow-On satellite, two Orbcomm satellites were carried into orbit by a Taurus rocket launched from Vandenberg Air Force Base on February 10, 1998.
  • At 2:11 p.m. on December 23, 1997, a Pegasus XL rocket carrying eight satellites was launched from a L-1011 aircraft off the coast of Virginia. Seventy-two minutes later the satellites were injected into their target orbits approximately 500 miles above the earth.
  • Two satellites were launched in April of 1995, from which intermittent commercial service was started in 1996.

These low earth orbit (LEO) satellites are designed to communicate with low-data rate subscriber communicators (SCs) and fixed site stations.

Date Launch Site Vehicle Count
December 4, 1999 Off the coast
Virginia
Pegasus XL via L-1011 7
September 23, 1998 Off the coast
Virginia
Pegasus XL via L-1011 8
August 2, 1998 Off the coast
Virginia
Pegasus XL via L-1011 8
February 2, 1998 Vandenberg Air Force Base
California
Taurus 2
December 23, 1997 Off the coast
Virginia
Pegasus XL via L-1011 8
April 3, 1995 Vandenberg Air Force Base
California
Pegasus XL via L-1011 2


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Updated August 18, 2001 (brief update February 6, 2009, February 8, 2014 and April 14, 2016).