The accuracy of Unicore GNSS receivers ranges all the way from meter, though sub-meter and centimeter, down to the millimeter level.

Using our own unique technology Unicore has successfully developed and fielded series of multi-system, multi-frequency, high-performance System on a Chip (SoC), and a range of high-precision, board-level GNSS receivers and navigation/timing modules.

Applications include Continuously Operating Reference System (CORS) reference stations, survey & mapping, precision agriculture, positioning & heading, vehicle monitoring, autonomous vehicle navigation, and precision timing – along with a number of other

Unicore is a one-stop provider of GNSS SoC chips and GNSS receivers, with extensive experience in the design, verification, development, implementation and production of highly integrated ICs, along with multi-system high-performance GNSS baseband algorit

Unicore Communications, Inc. is a technology company focused on the design & development of highly integrated ICs, algorithms and GNSS receivers.

Home > Product Center > UM4B0


BDS/GPS/GLONASS/GALILEO Quad-System High Precision Heading Module

Product Introduction

UM4B0 is the smallest high precision positioning and heading module in the world. Based on Nebulas-II SoC, it can track all current visible GNSS satellite signals, including BDS B1/B2/B3, GPS L1/L2/L5, GLONASS L1/L2, Galileo E1/E5a/E5b and QZSS L1/L2/L5. With a 6-axis on-board MEMS, it supports autonomous integrated navigation. Its targeted application fields include light-weight robots, GIS, intelligent driving, UAV etc.

The smallest multi-system multi-frequency RTK Module

UM4B0 is the first multi-constellation and multi-frequency RTK SMD module in the world (30x40 mm). With the highest level of integration among the industry, this module contributes to a significant reduction of terminal size.

Integrated MEMS Navigation

The UB4B0M integrates 6-axis on-board MEMS chip and U-Fusion INS algorithm, resulting in optimized continuity and reliability of accurate heading and positioning output in tough environments such as city canyons, tunnels and overpasses. The board also supports odometer inputs to provide better navigation and positioning performance.

UGypsophila RTK processing technology

Coupled with a high-performance data-sharing capability and simplified operating system within the Nebulas II, UM4B0 performs sufficient optimization on the multi-dimensional RTK matrix computation. The receiver will try to track all visible satellites of all systems to be used in the RTK and heading solutions, resulting in a shortened RTK initialization time of 5 seconds and improved accuracy and reliability.

Nebulas-II GNSS SoC

UM4B0 is based on Unicore's Nebulas-II multi-system, multi-core, high precision SoC. The SoC supports 432 channels, includes a built-in high performance ADC, an anti-interference unit, two 600MHz ARM processors and two precision floating-point processing units, providing powerful GNSS signal processing capability.

Product Features

• 30x40 mm

• 20 Hz RTK update rate

• Integrated 6-axis MEMS chip and capable of independent integrated navigation

• Advanced multi-path mitigation technology

• Centimeter-level RTK positioning

• Multiple physical interfaces including serial port, SPI, IPPS, Event

• Adaptive recognition of RTCM format

Data Manual

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Technical Index

Performance Specifications


432 channels, based on Nebulas-II chip

Velocity Accuracy (RMS)

0.03 m/s

Frequency BDS B1/B2/B3

Time to First Fix (TTFF)

Cold start< 25 s

GPS L1/L2/L5

Initialization time

< 5 s (typical)


Initialization reliability

> 99.9%

Galileo E1/E5a/E5b


< 1 s



RTCM v2.3/3.0/3.2


Data Output

NMEA-0183,Unicore Binary

Single point positioning

Horizontal:1.5 m

Update Rate

20 Hz

Vertical:2.5 m

Time accuracy (RMS)

20 ns


Horizontal:0.4 m

Dead Reckoning Error <5% of distance travelled during GPS denied conditions

Vertical:0.8 m



Horizontal:10 mm + 1 ppm


Vertical:15 mm + 1 ppm


Physical Specifications


30 × 40 × 4 mm



Functional Ports

3x UART, 1xI2C, 1x SPI (LV-TTL)


1xEvent input

Note: * represents optional configuration

Environmental Specifications


Working: -40℃~+85℃

Storage: -55℃~+95℃


95% No condensation





Electrical Specifications


3.3 VDC +5%/–3%


4.75~5.0 V, 0~100 mA

Ripple Voltage

100 mV p-p(max)

Power Consumption

1.8 W (typical)

Application Area