Spectracom's Satellite Time and Location (STL) signal is broadcast on Iridium satellites and offers a spoofing-resilient encrypted signal that is significantly stronger than the GPS-based timing signal. Hence, it is harder to jam, and can be received indoors.
STL is a subscription-based service. For details contact Spectracom.
A SecureSync equipped with the STL 1204-3D option card can be operated with or without GPS, depending on your application, i.e. STL can be utilized as a backup, or as the only external timing source.
Note: During the initial installation of a unit equipped with an STL module, the exact geographic position needs to be entered into the Web UI (see below). Should the unit be relocated at a later point in time, the position must be changed accordingly.
Model 1204-3D STL In: Specifications
- Inputs: One STL antenna input, one Ethernet maintenance input
- Antenna input connector: SMA
- Ethernet connector: RJ45
- Frequency band: 1620 MHz
- Timing synchronization accuracy to UTC: ±500 ns (specified); ±200 ns (typical)
- Positioning accuracy: 30-50 m
- Coverage: Global
- Time-to-first-fix (Timing): Several seconds (the PPS pulse will become available once the positioning fix has been obtained)
- Time-to-first-fix (Positioning): Approximately 10 minutes
- Jamming resilience: Signal is 30 to 40 dB stronger than GPS signal
- Spoofing resilience: Encrypted signal
- Maximum number of cards: 1
- Ordering information: 1204-3D: STL module
- Ordering notes: The STL module 1204-3D cannot be combined with a Rubidium oscillator.
Model 1204-3D option card rear plate
Installing the STL Antenna
The supplied STL satellite antenna is designed for indoor use. The ideal location for the antenna is near the ceiling of the room in which your SecureSync unit is located, or near an outside wall. In general, a higher location is preferable over a lower location. Do not cover the antenna with electronic equipment or other metal objects.
The STL option card 1204-3D can be configured via the SecureSync Web UI.
To configure or review STL settings:
- Navigate to INTERFACES > REFERENCES: STL. The STL status panel will be displayed.
- In the STL status panel ...
- … either click the INFO button to review STL status (see Reviewing the STL Status),
- … or click the GEAR button to edit STL settings: The STL Setup window will open.
In the STL Setup window, the following parameters can be configured:
Note: For initial setup, you need to enter only Latitude and Longitude. With the majority of STL applications, all other parameters can be left unchanged, i.e. at their default settings.
- Latitude, Longitude, Altitude: [decimal degrees, meters] Actual geographic position of SecureSync's STL antenna. For help determining your actual position, see Determining Your Position.
- EE axis, NN axis, UU axis: [in meters; default = 100] East, North, Up axis, used to setup an ENU uncertainty reference frame around the known ECEF position entered above.
- Geolocation Mode:
Static Known Position/Static Unknown Position [default]/Pseudo Static/Dynamic: This parameter refers to how the STL receiver handles position estimation. The default setting is recommended for most applications.
- Sensitivity Level: [default = 40] This value determines the sensitivity of the STL receiver towards the STL signal bursts transmitted by the satellites. The lower the number, the more responsive the receiver will be to acknowledge the bursts. The default value is optimized for an indoor antenna. A higher value can be tried out for outdoor antennas. A value lower than (40) is not recommended.
The three ENU axis values represent variance values around the known receiver/antenna position.
Ideally, the variance values should reflect the expected error [NSvar(m) EWvar(m) Altvar(m)] of the guess position. For example, if you know that your position is within 100 m of the actual position, then the variance should be set to 100 for best performance. If the uncertainty of your position is 1km, the variance should be set to 1000. When using Google Maps™ (as described in Determining Your Position) you can obtain a reasonably accurate position, even though the precise elevation is fairly difficult to determine.
While the main objective is to use variance values that match the actual inaccuracy of your guess position, the default values of 100 m in most cases will result in a good convergence time and accuracy.
To obtain a detailed STL status overview:
- Navigate to INTERFACES > REFERENCES: STL 0. The STL status panel will be displayed.
- In the STL status panel, click the INFO button. The STL status window will open.
Besides STL system data the window also displays STL validity and the subscription status. For a description of the other parameters, see Configuring STL Settings.