Naelcom Lassen SKII Clone

Replace Legacy Lassen SKII Modules

Manufacturer: Naelcom
Naelcom Lassen SKII Clone

NLC-SKII is a GPS receiver based upon the popular Trimble Copernicus II surface-mount receiver. It has been designed to be a fit/form replacement for the end of life Trimble Lassen SKII module.


Mechanical - The NLC-SKII has the same mechanical dimensions as the Lassen SKII. It has the same 8 pin data connector as the SKII and has the same SMB antenna connector (both located in the exact same locations as found on the SKII). The Copernicus II does not require a metal shield, which was an add-on option for the original Lassen SKII.

GPS Protocol - The Lassen SKII supported Trimble's TSIP (Trimble's own binary based protocol), NMEA (industry-standard ASCII protocol) and TAIP (Trimble's own ACSII protocol). The Copernicus II supports all of these protocols.

Serial Interface - the Copernicus II has one limitation which is that the serial port parity is not configurable (only 'NO' parity is supported). Trimble's Lassen SKII supported ODD, EVEN and NO parity with a default of ODD parity. This default setting might affect compatibility for some customers.

Performance: The Copernicus II is a far superior product to the SKII. It supports more concurrent satellite tracking, faster startup and is much more sensitive.


This module can replace all released Lassen SKII modules including:

  • Trimble 38116-20 Lassen SKII  (Non-RoHS)
  • Trimble 38116-25 Lassen SKII  (RoHS)


GeneralL1 (1575.42 MHz) frequency, C/A code
12-channel, continuous tracking receiver
Update rateTSIP @ 1 Hz; NMEA @ 1 Hz; TAIP @ 1 Hz
AccuracyHorizontal: <2.5 meters (50%), <5 meters (90%)
Horizontal (with SBAS accuracy): <2 meters (50%), <4 meters (90%)
Altitude: <5 meters (50%), <8 meters (90%)
Altitude (with SBAS accuracy): <3 meters (50%), <5 meters (90%)
Velocity: 0.06 m/sec
Static PPS: ±60 nanoseconds
PPS (Stationary Mode "indoor" @ –145dBm): ±350 nanoseconds
AcquisitionReacquisition: 2 sec
Hot Start (with battery): 3 sec
Hot Start (no battery): 8 sec (ephemeris not older than 4 hours)
Warm Start: 35 sec
Cold Start: 38 sec
Out of the Box: 41 sec
Operational LimitsVelocity: 515 m/s
Receiver Dynamics: 2G
SensitivityTracking Sensitivity: -160dBm
Acquisition Sensitivity: -148dBm*
* For hot start with ephemeris, otherwise -146dBm
PPS5.0 V CMOS-compatible pulse, once per second
ProtocolsTSIP, default: 38400, 8, None, 1 (parity not configurable)
NMEA, default: 4800, 8, None, 1 (parity not configurable)
TAIP, default: 4800, 8, None, 1 (parity not configurable)
Note: These are the defaults of the Copernicus II - all but parity can be changed via a Trimble software tool (either individually or in batch mode)
Serial PortsTwo 5.0 V CMOS, TTL compatible serial ports


ElectricalPrime Power: 5VDC, ±5%
Power consumption (board only): 65mA
Back-up power: +2.7 to +5V DC
Back-up consumption: 7 microAmps @ +3.0V
• RF: SMB;
• I/O: 8-pin (2x4), 0.1" / 2.54 mm header

Dimensions: 82.6 mm x 31.2 mm x 10.2 mm
TemperatureTemperature range (operation): -40 to +85°C
Temperature range (storage): -55 to +100°C
Humidity5% to 95% RH non-condensing @ 60°C
Warranty1 Year



BoardNLC-SKII-CP2-V2.0 Lassen SKII clone based upon Copernicus II module
Accessories66800-40 5.0V, 27dB GPS antenna, mag mount, 5 meter cable, SMA connector
57860-30 Bullet III 5.0V GPS antenna F-style connector, 35dB gain
57860-20 Bullet III 5.0V GPS antenna TNC connector, 35dB gain
70228-70 5.0V Hardmount GPS Antenna with TNC connector, 28 dB gain
Recab UK
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