unicore UM981 User manual

INSTALLATION AND OPERATION
USER MANUAL
WWW.UNICORECOMM.COM
Copyright© 2009-2023, Unicore Communications, Inc.
Data subject to change without notice.
UM981
BDS/GPS/GLONASS/Galileo/QZSS
All-constellation Multi-frequency
RTK/INS Integrated Positioning Module

i
Revision History
Version
Revision History
Date
R1.0
First release
Sept. 2023
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Information, such as product specifications, descriptions, features and user guide in this
manual, are subject to change by Unicore at any time without prior notice, which may
not be completely consistent with such information of the specific product you
purchase.

UM981 User Manual
ii
Should you purchase our product and encounter any inconsistency, please contact us or
our local authorized distributor for the most up-to-date version of this manual along
with any addenda or corrigenda.

iii
Foreword
This document describes the hardware information, specifications, packaging and the
use of Unicore UM981 modules.
Target Readers
This document is written for technicians who are familiar with GNSS modules.

UM981 User Manual
I
Contents
1Introduction...............................................................................................1
1.1 Key Features.....................................................................................................................2
1.2 Key Specifications ...........................................................................................................2
1.3 Block Diagram..................................................................................................................5
2Hardware ...................................................................................................6
2.1 Pin Definition....................................................................................................................6
2.2 Electrical Specifications............................................................................................... 10
2.2.1 Absolute Maximum Ratings......................................................................................10
2.2.2 Operating Conditions.................................................................................................11
2.2.3 IO Threshold ...............................................................................................................11
2.2.4 Antenna Feature.........................................................................................................12
2.3 Dimensions ................................................................................................................... 12
3Hardware Design .....................................................................................14
3.1 Recommended Minimal Design................................................................................... 14
3.2 Antenna Feed Design ................................................................................................... 15
3.3 Power-on and Power-off ............................................................................................. 16
3.4Grounding and Heat Dissipation ................................................................................. 17
3.5 Recommended PCB Package Design ......................................................................... 17
4Production Requirement..........................................................................18
5Packaging................................................................................................19
5.1 Label Description.......................................................................................................... 19
5.2 Product Packaging ....................................................................................................... 19

UC-00-M33 EN R1.0 Introduction 1
1Introduction
UM981 is a new generation of GNSS high precision RTK/INS integrated positioning
module from Unicore. It supports BDS/GPS/GLONASS/Galileo/QZSS all constellations
and can simultaneously track BDS B1I/B2I/B3I/B1C/B2a/B2b, GPS L1/L2/L5, GLONASS
G1/G2/G3, Galileo E1/E5a/E5b/E6, QZSS L1/L2/L5, NavIC L5 and SBAS. The module is
mainly used in surveying and mapping, intelligent driving*, precision agriculture, etc.
UM981 is based on NebulasIVTM, a GNSS SoC which integrates the RF-baseband and
high precision algorithm. Besides, the SoC integrates a dual-core CPU, a high speed
floating point processor and an RTK co-processor. It is processed with 22 nm low power
design and supports 1408 channels, being able to output 100 Hz IMU raw data and up to
50 Hz*RTK positioning result, providing powerful data processing ability.
With the built-in JamShield anti-jamming technology, UM981 has improved the
performance of RTK solution for multiple modes and frequencies, ensuring fast RTK
initialization speed, high accuracy of measurement and high reliability even in the most
challenging environments such as urban canyons and tree shades.
Furthermore, UM981 supports various interfaces such as UART, I2C*, SPI*, as well as
1PPS, EVENT, CAN*, which meets customers’ needs in different applications.
Figure 1-1 UM981 Module
*The application marked with an asterisk is supported by customized model or firmware.
*Data update rate can reach 50 Hz after firmware upgrade.
*I2C, SPI, CAN: reserved interfaces, not supported currently

UM981 User Manual
2 Introduction UC-00-M33 EN R1.0
1.1 Key Features
Based on the new generation GNSS SoC - NebulasIVTM, which integrates RF-
baseband and high precision algorithm
17 mm ×22 mm ×2.6 mm, surface-mount device
Supports all-constellation multi-frequency on-chip RTK positioning solution
Supports BDS B1I/B2I/B3I/B1C/B2a/B2b + GPS L1/L2/L5 + GLONASS G1/G2/G3 +
Galileo E1/E5a/E5b/E6 + QZSS L1/L2/L5 + NavIC L5 + SBAS
All-constellation multi-frequency RTK engine and advanced RTK processing
technology
Instantaneous RTK initialization technology
Independent tracking of different frequencies and 60 dB narrowband anti-jamming
technology
100 Hz IMU raw data output and up to 50 Hz*RTK positioning result output
1.2 Key Specifications
Table 1-1 Technical Specifications
Basic Information
Channels
1408 channels, based on NebulasIVTM
Constellations
BDS/GPS/GLONASS/Galileo/QZSS
Frequencies
BDS: B1I, B2I, B3I, B1C, B2a, B2b
GPS: L1 C/A, L1C, L2P (Y), L2C, L5
GLONASS: G1, G2, G3
Galileo: E1, E5a, E5b, E6
QZSS: L1, L2, L5
NavIC: L5
Power
Voltage
+3.0 V ~ +3.6 V DC
Power Consumption
480 mW (Typical)

UC-00-M33 EN R1.0 Introduction 3
Performance
Positioning Accuracy
Single Point
Positioning1
(RMS)
Horizontal: 1.5 m
Vertical: 2.5 m
DGPS (RMS)1,2
Horizontal: 0.4 m
Vertical: 0.8 m
RTK (RMS)1,2
Horizontal: 0.8 cm + 1 ppm
Vertical: 1.5 cm + 1 ppm
Tilt
Measurement
10 mm + 0.7 mm/°tilt
(accuracy < 2.5 cm within 30°)
Attitude Accuracy
Heading
0.3°
Roll
0.2°
Pitch
0.2°
Observation Accuracy (RMS)
BDS
GPS
GLONASS
Galileo
B1I/B1C/L1C/L1 C/A/G1/E1
Pseudorange
10 cm
10 cm
10 cm
10 cm
B1I/B1C/L1C/L1 C/A/G1/E1
Carrier Phase
1 mm
1 mm
1 mm
1 mm
B3I/L2P(Y)/L2C/G2/E6
Pseudorange
10 cm
10 cm
10 cm
10 cm
B3I/L2P(Y)/L2C/G2/E6
Carrier Phase
1 mm
1 mm
1 mm
1 mm
B2I/B2a/B2b/L5/G3/E5a/E5b
Pseudorange
10 cm
10 cm
10 cm
10 cm
1
Test results may be biased due to atmospheric conditions, baseline length, GNSS antenna type,
multipath effect, number of visible satellites, and satellite geometry.
2
The measurement uses 1 km baseline and a receiver with good antenna performance, regardless of
possible errors of antenna phase center offset.

UM981 User Manual
4 Introduction UC-00-M33 EN R1.0
B2I/B2a/B2b/L5/G3/E5a/E5b
Carrier Phase
1 mm
1 mm
1 mm
1 mm
Time Pulse Accuracy (RMS)
20 ns
Velocity Accuracy3(RMS)
0.03 m/s
Time to First Fix4(TTFF)
Cold Start < 12 s
Hot Start < 4 s
Initialization Time1
< 5 s (Typical)
Initialization Reliability1
> 99.9%
Data Update Rate5
100 Hz IMU raw data output
50 Hz RTK positioning result output
Differential Data
RTCM 3.X
Data Format
NMEA-0183, Unicore
Physical Characteristics
Package
54 pin LGA
Dimensions
22 mm × 17 mm × 2.6 mm
Weight
1.91 g ± 0.03 g
Environmental Specifications
Operating Temperature
-40 °C~ +85 °C
Storage Temperature
-55 °C~ +95 °C
Humidity
95% No condensation
Vibration
GJB150.16A-2009, MIL-STD-810F
Shock
GJB150.18A-2009, MIL-STD-810F
3
Open sky, unobstructed scene, 99% @ static
4
-130dBm @ more than 12 available satellites
5
The 50 Hz data update rate is supported after firmware upgrade

UC-00-M33 EN R1.0 Introduction 5
Functional Ports
UART × 3
I2C*× 1
SPI* × 1
Slave
CAN*× 1
Shared with UART3
1.3 Block Diagram
RF in SAW
Filter
NebulasIV
GNSS
RF
GNSS
BB
LNA
Interface
PMUInterface
IMU I2C
CLOCK
TCXO
32K
SPI
RESET_N
UART1/2/3
I2C
SPIS
PVT/RTK/ERR
EVENT
PPS
Figure 1-2 UM981 Block Diagram
RF Part
The receiver gets filtered and enhanced GNSS signal from the antenna via a coaxial
cable. The RF part converts the RF input signals into the IF signals, and converts IF
analog signals into digital signals required for NebulasIVTM chip (UC9810).
NebulasIVTM SoC (UC9810)
NebulasIV (UC9810) is UNICORECOMM’s new generation high precision GNSS SoC with
*I2C, SPI, CAN: reserved interfaces, not supported currently

UM981 User Manual
6 Hardware UC-00-M33 EN R1.0
22 nm low power design, supporting all constellations and all frequencies with 1408
channels. It integrates a dual-core CPU, a high speed floating point processor and an
RTK co-processor, which can fulfill the high precision baseband processing and RTK
positioning on a single chip.
External Interfaces
The external interfaces of UM981 include UART, I2C*, SPI*, CAN*, PPS, EVENT, RTK_STAT,
PVT_STAT, ERR_STAT, RESET_N, etc.
2Hardware
2.1 Pin Definition
12345678910 11 12 13 14
42
43
44
45
46
47
48
49
50
51
52
53
54
27
26
25
24
23
22
21
20
19
18
17
16
15
41 40 39 38 37 36 35 34 33 32 31 30 29 28
GND
ANT_IN
GND
ANT_DETECT
ANT_OFF
ANT_SHORT_N
VCC_RF
SPIS_CSN
SPIS_MOSI
SPIS_CLK
SPIS_MISO
GND
GND
RSV
NC
NC
NC
NC
PVT_STAT
RTK_STAT
ERR_STAT
RSV
RSV
NC
NC
RXD2
TXD2
BIF BIF
TXD3 RXD3
GND VCC
VCC RSV
V_BCKP GND
NC NC
NC GND
TXD1
RXD1
SDA
SCL
NC
NC
GND
RESET_N
NC
EVENT
NC
PPS
NC
Top View
Figure 2-1 UM981 Pin Definition
*I2C, SPI, CAN: reserved interfaces, not supported currently

UC-00-M33 EN R1.0 Hardware 7
Table 2-1 Pin Description
No.
Pin
I/O
Description
1
GND
—
Ground
2
ANT_IN
I
GNSS antenna signal input
3
GND
—
Ground
4
ANT_DETECT
I
Antenna signal detection
5
ANT_OFF
O
Disable external LNA
6
ANT_SHORT_N
I
Antenna short circuit detection; active low
7
VCC_RF6
O
External LNA power supply
8
SPIS_CSN
I
Chip select pin for SPI slave
9
SPIS_MOSI
I
Master Out / Slave In. This pin is used to
receive data in slave mode.
10
SPIS_CLK
I
Clock input pin for SPI slave
11
SPIS_MISO
O
Master In / Slave Out. This pin is used to
transmit data in slave mode.
12
GND
—
Ground
13
RSV
—
Reserved
14
GND
—
Ground
15
NC
—
No connection inside
16
NC
—
No connection inside
17
NC
—
No connection inside
18
NC
—
No connection inside
6
Not recommended to take VCC_RF as ANT_BIAS to feed the antenna. See section 3.2 for more
details.

UM981 User Manual
8 Hardware UC-00-M33 EN R1.0
No.
Pin
I/O
Description
19
PVT_STAT
O
PVT status: active high;
Outputs high when positioning and low when
not positioning
20
RTK_STAT
O
RTK status: active high;
Outputs high for RTK fixed solution and low
for other positioning status or no positioning
21
ERR_STAT
O
Error status: active high;
Outputs high when failing self-test and low
when passing self-test
22
RSV
—
Reserved, recommended to be floating
23
RSV
—
Reserved, recommended to be floating
24
NC
—
No connection inside
25
NC
—
No connection inside
26
RXD2
I
COM2 input, LVTTL
27
TXD2
O
COM2 output, LVTTL
28
BIF
—
Built-in function; recommended to add a
through-hole testing point and a 10 kΩ pull-
up resistor; cannot connect ground or power
supply or input/output data, but can be
floating
29
BIF
—
Built-in function; recommended to add a
through-hole testing point and a 10 kΩ pull-
up resistor; cannot connect ground or power
supply or input/output data, but can be
floating
30
TXD3
O
COM3 output, can be used as CAN TXD,
LVTTL
31
RXD3
I
COM3 input, can be used as CAN RXD, LVTTL
32
GND
—
Ground

UC-00-M33 EN R1.0 Hardware 9
No.
Pin
I/O
Description
33
VCC
I
Power supply
34
VCC
I
Power supply
35
RSV
—
Reserved
36
V_BCKP
I
When the main power supply VCC is cut off,
V_BCKP supplies power to RTC and relevant
register. Level requirement: 2.0 V ~ 3.6 V, and
the working current is less than 60 μA at
25 °C. If you do not use the hot start function,
connect V_BCKP to VCC. Do NOT connect it
to ground or leave it floating.
37
GND
—
Ground
38
NC
—
No connection inside
39
NC
—
No connection inside
40
NC
—
No connection inside
41
GND
—
Ground
42
TXD1
O
COM1 output, LVTTL
43
RXD1
I
COM1 input, LVTTL
44
SDA
I/O
I2C data
45
SCL
I/O
I2C clock
46
NC
—
No connection inside
47
NC
—
No connection inside
48
GND
—
Ground
49
RESET_N
I
System reset; active Low. The active time
should be no less than 5 ms.
50
NC
—
No connection inside

UM981 User Manual
10 Hardware UC-00-M33 EN R1.0
No.
Pin
I/O
Description
51
EVENT
I
Event mark input, with adjustable frequency
and polarity
52
NC
—
No connection inside
53
PPS
O
Pulse per second, with adjustable pulse
width and polarity
54
NC
—
No connection inside
2.2 Electrical Specifications
2.2.1 Absolute Maximum Ratings
Table 2-2 Absolute Maximum Ratings
Parameter
Symbol
Min.
Max.
Unit
Power Supply Voltage
VCC
-0.3
3.6
V
Input Voltage
Vin
-0.3
3.6
V
GNSS Antenna Signal Input
ANT_IN
-0.3
6
V
Antenna RF Input Power
ANT_IN input
power
+10
dBm
External LNA Power Supply
VCC_RF
-0.3
3.6
V
VCC_RF Output Current
ICC_RF
100
mA
Storage Temperature
Tstg
-55
95
°C

UC-00-M33 EN R1.0 Hardware 11
2.2.2 Operating Conditions
Table 2-3 Operating Conditions
Parameter
Symbol
Min.
Typ.
Max.
Unit
Condition
Power Supply Voltage7
VCC
3.0
3.3
3.6
V
Maximum VCC Ripple
Vrpp
0
50
mV
Working Current8
Iopr
145
180
mA
VCC=3.3 V
VCC_RF Output Voltage
VCC_RF
VCC-0.1
V
VCC_RF Output Current
ICC_RF
50
mA
Operating Temperature
Topr
-40
85
°C
Power Consumption
P
480
mW
2.2.3 IO Threshold
Table 2-4 IO Threshold
Parameter
Symbol
Min.
Typ.
Max.
Unit
Condition
Low Level Input Voltage
Vin_low
0
0.6
V
High Level Input Voltage
Vin_high
VCC ×
0.7
VCC +
0.2
V
Low Level Output Voltage
Vout_low
0
0.45
V
Iout = 2 mA
High Level Output
Voltage
Vout_high
VCC -
0.45
VCC
V
Iout = 2 mA
7
The voltage range of VCC (3.0 V ~ 3.6 V) has already included the ripple voltage.
8
Since the product has capacitors inside, inrush current occurs during power-on. You should evaluate
in the actual environment in order to check the effect of the supply voltage drop caused by inrush
current in the system.

UM981 User Manual
12 Hardware UC-00-M33 EN R1.0
2.2.4 Antenna Feature
Table 2-5 Antenna Feature
Parameter
Symbol
Min.
Typ.
Max.
Unit
Condition
Optimum Input
Gain
Gant
18
30
36
dB
2.3 Dimensions
Table 2-6 Dimensions
Parameter
Min. (mm)
Typ. (mm)
Max. (mm)
A
21.80
22.00
22.50
B
16.80
17.00
17.50
C
2.40
2.60
2.80
D
3.75
3.85
3.95
E
0.95
1.05
1.15
F
1.80
1.90
2.00
G
1.00
1.10
1.20
H
0.70
0.80
0.90
K
1.40
1.50
1.60
M
3.55
3.65
3.75
N
3.15
3.25
3.35
P
2.00
2.10
2.20
R
1.00
1.10
1.20
X
0.72
0.82
0.92

UC-00-M33 EN R1.0 Hardware 13
Figure 2-2 UM981 Mechanical Dimensions

UM981 User Manual
14 Hardware Design UC-00-M33 EN R1.0
3Hardware Design
3.1 Recommended Minimal Design
UM982
ANT
HOSTUM981
3.3V
VCCV_BCKP
ANT_BIAS
ANT_IN
TXD
RXD
RESET_N
GND GND
L1
C1
C2
C3
BIFBIF
3.3V
R1 R1
TXD (UART)
RXD (UART)
IO
Figure 3-1 Recommended Minimal Design
L1: 68 nH RF inductor in 0603 package is recommended
C1: 100 nF + 100 pF capacitors connected in parallel is recommended
C2: 100 pF capacitor is recommended
C3: N * 10 μF + 1 * 100 nF capacitors connected in parallel is recommended, and the
total inductance should be no less than 30 μF
R1: 10 kΩ resistor is recommended

UC-00-M33 EN R1.0 Hardware Design 15
3.2 Antenna Feed Design
UM981 just supports feeding the antenna from the outside of the module rather than
from the inside. It is recommended to use devices with high power and that can
withstand high voltage. Gas discharge tube, varistor, TVS tube and other high-power
protective devices may also be used in the power supply circuit to further protect the
module from lightning strike and surge.
If the antenna feed supply ANT_BIAS and the module’s main supply VCC use the
same power rail, the ESD, surge and overvoltage from the antenna will have an
effect on VCC, which may cause damage to the module. Therefore, it is
recommended to design an independent power rail for the ANT_BIAS to reduce the
possibility of module damage.
UM981
ANT_IN
ANT
VCC_RF
GND
C2
ANT_BIAS
L1
C1D1 D2
Figure 3-2 UM981 External Antenna Feed Reference Circuit
Notes:
1. L1: feed inductor, 68 nH RF inductor in 0603 package is recommended
2. C1: decoupling capacitor, recommended to connect two capacitors of
100 nF/100 pF in parallel
3. C2: DC blocking capacitor, recommended 100 pF capacitor