The Satellite Communications Facility (SCF) at the Johns Hopkins University Applied Physics Laboratory (APL) traces its genesis to the early days of Sputnik. Since the first signal from space, APL has provided the nation with global timing and positioning solutions, world class space and planetary science, robust and reliable spacecraft, and precise navigation, commanding and communications to ensure mission success.
|Location||39:10 N, 76:53 W|
Established in 1961 to support the command and telemetry requirements of the world's first satellite navigation system under contract to the U.S. Navy, the APL station has provided more than 50 years of ground contact support to our sponsors. The station has conducted over 100,000 satellite contacts in the last 15 years alone. With available, on-call technical support, the station has been conducting attended and unattended spacecraft tracking operations since 1995.
Assets at APL include two independent operational antenna systems. Our mid-latitude station can be configured to support a wide variety of missions ranging from Low Earth Orbit (LEO) through Deep Space, with a variety of data formats, including TDM and CCSDS. Current capabilities include support for L-band, S-band, and X-band communications. Quick and efficient use of antenna assets, with a 3-minute station setup and a 1-minute station tear down between contacts.
Recent system improvements and technology enhancements enable these systems to provide future sponsors with advanced capability at cost-effective rates. APL's concept of a Shared Service, Multi-mission Ground System makes the remote scheduling and data transfer capabilities of these systems highly attractive for government, academia, and commercial operations on a non-exclusive basis. While currently these systems are conducting routine daily contacts, their availability for additional contacts is still over 60%. Portions of these facilities are owned by the U.S. government and some restrictions on their use may apply.
|Frequency Range||2200-2400 MHz||8400-8500 MHz|
|Polarization||Simultaneous RHC and LHC||Simultaneous RHC and LHC|
|G/T||>28.3 dB/K||>38.5 dB/K|
|Beamwidth||0.5 deg||0.13 deg|
|Frequency Range||2025-2120 MHz|
|Polarization||"On-the-fly" Selectable LHC or RHC|
|Transmitter||2000 W Klystron (dual redundant)|
|Antenna Pointing Control|
|Program track (TLE, Spice-SPK, Chebychev, RA/DEC), S-band Autotrack, S/X-band Steptrack|
|Command, Ranging, Doppler & Telemetry, including Turbo (r1/2, 1/3, 1/4, 1/6), Convolutional (r1/2), Reed-Solomon, and Conv/R-S; Wide variety of modulation formats; Space Link Extension "SLE" (Fwd CLTU, RAF, & RCF services)|
|Frequency Range||1650-1750 MHz||2200-2300 MHz||8000-8500 MHz|
|G/T||>11.2 dB/K||>13.6 dB/K||>24.1 dB/K|
|Beamwidth||2.5 deg||1.8 deg||0.5 deg|
|Antenna Pointing Control|
|Program track (TLE, Spice-SPK, Chebychev Polynomials. RA/DEC)|
TWT-1-009 8 April, 1963 E. F. Snyder
Johns Hopkins APL Technical Digest, Jan. - Mar. 1998, V19#1
Photo Archives of the Satellite Communications Facility
The Construction of the 60 Foot Antenna at APL, nearly Fifty Years Ago.
As a result of the success of the early work done for the Navy on the concept of satellite based navigation, the Transit Program was about to become a reality. Two ground stations would need to be constructed to support the continuing work as the program headed toward an operational system.
By the 15th of November, 1962 Work on the APL Station had already begun. The first foundation, a donut shape had been determined to be inadequate and subsequently destroyed. A second foundation, approved by APL engineers was now entering the first phases of construction.
This second foundation is a rooted structure with 20 poured, steel reinforced concrete pylons 35 feet deep. Eight of the 20 pylons are drilled holes 48 inches in diameter, loaded with a welded steel reinforcement cages followed by poured concrete. The remaining 12 pylons are 14 inch diameter driven piles filled with poured concrete.
A total of more than 500 cubic yards of concrete are contained in the foundation with an estimated weight in excess of 2 Million pounds.
Drilling Hole #1 of the foundation
(notice Building 36 and several pylons in the background
Drilling Hole #8 of the foundation
(Also visible in the background, the helix antennas on Bld. 36)
Lifting a 35 foot long 3 ft. diameter Reinforcment cage into the hole.