User Manual

LEA-6 - Data Sheet
GPS.G6-HW-09004-E2 Page 12 of 26
1.15 Precision Timing & Raw Data (LEA-6T)
Timing and Raw data features are available in two Module versions, the LEA-6T-0 and the LEA-6T-1. Both are
pin-compatible Modules. The LEA-6T-1 includes an internal Flash memory for firmware updates.
1.15.1 Time mode
LEA-6T provides a special Time Mode to provide higher timing accuracy. The LEA-6T is designed for use with
stationary antenna setups. The Time Mode features three different settings described in Table 9: Disabled,
Survey-In and Fixed Mode. For optimal performance entering the position of the antenna (when known) is
recommended as potential source of errors will be reduced.
Time Mode Settings Description
Disabled Standard PVT operation
Survey-In The GPS receiver computes the average position over an extended time period until a predefined
maximum standard deviation has been reached. Afterwards the receiver will be automatically set to
Fixed Mode and the timing features will be activated.
Fixed Mode In this mode, a fixed 3D position and known standard deviation is assumed and the timing features are
activated. Fixed Mode can either be activated directly by feeding pre-defined position coordinates (ECEF
- Earth Center Earth Fixed format) or by performing a Survey-In.
In Fixed mode, the timing errors in the TIMEPULSE signal which otherwise result from positioning errors
are eliminated. Single-satellite operation is supported. For details, please refer to the u-blox 6 Receiver
Description including Protocol Specification [2].
Table 9: Time mode settings
1.15.2 Timepulse and frequency reference
LEA-6T not only features the new u-blox 6 engine with its extra acquisition sensitivity, it also comes with a 2nd
timepulse output, which can be configured from 0.25 Hz up to 10 MHz. One timepulse can be used for time
synchronization (i.e. 1 pulse per second), while the 2nd timepulse can be used with LEA-6T as a reference
frequency in the MHz range. A timepulse in the MHz range provides excellent long-term frequency accuracy and
stability. This brings cost savings for LEA-6T customers since it is no longer necessary to generate an additional
reference frequency with their circuitry.
1.15.3 Time mark
LEA-6T can be used for precise time measurements with sub-microsecond resolution using the external interrupt
(EXTINT0). Rising and falling edges of these signals are time-stamped to the GPS or UTC time and counted. The
Time Mark functionality can be enabled with the UBX-CFG-TM2 message
For details, please refer to the u-blox 6 Receiver Description including Protocol Specification [2].
1.15.4 Raw data
Raw data output is supported at an update rate of 5 Hz on the LEA-6T-0 and 2 Hz on the LEA-6T-1. The UBX-
RXM-RAW message includes carrier phase with half-cycle ambiguity resolved, code phase and Doppler
measurements, which can be used in external applications that offer precision positioning, real-time kinematics
(RTK) and attitude sensing.