nanoradar SR-PA24R User manual

24G Radar Altimeter
（SR-PA24R）
User Manual
Version：V1.0
Hunan Nanoradar Science and Technology Co., Ltd.

Disclaimers
Thanks to purchase this product. There is web pages about NRA24 altimeter in
our official website (www.nanoradar.cn).You can find the latest product information
and user manual on the pages. The user manual is subject to change without notice.
Please read this manual carefully before using this product. Once used, it is
deemed to have recognized and accepted the content of this manual. Please strictly
follow the manual to install and use the product. Any improper use may cause
damage or injury, and Nanoradar would not bear the corresponding loss and liability.
Product copyright is retained by Nanoradar. Reproduction in any form shall not be
done without permission. The use of this product and manual shall not be pursued
liability for the patent.
Version History
Date
Version
Description
2019-04-23
1.0
SR-PA24R user manual v1.0

Content
1 SR-PA24R Introduction...............................................................................................4
2 Precautions.................................................................................................................. 4
3 Radar Parameter.......................................................................................................... 5
4 quick use steps.............................................................................................................5
4.1 Pin Definition................................................................................................... 5
4.2 Test................................................................................................................... 5
5 Data Parsing................................................................................................................ 6
6 open source platform................................................................................................... 6
6.1 Radar installation and wiring........................................................................... 7
6.2 MissionPlanner Ground station for flight control parameter setting................8
7 FAQ............................................................................................................................. 9

1 SR-PA24R Introduction
SR-PA24R is a professional 24G millimeter-wave radar altimeter for industrial drones.
It uses 24GHz-ISM frequency band, with 2cm measurement accuracy, compact size,
high sensitivity, light weight, easy integration and stable performance. The radar can
output the distance from the drone to the ground in real time with strong
anti-interference ability. It can work in the all-weather environment. The product can
be directly adapted to DJI A3/N3 FCU, DJI M600 Pro, Pixhawk and other flight
platforms.
Dimension：130×70×14.5(mm)
Weight：120g
Figure 1 SR-PA24R outline
2 Precautions
(1) The power supply pin needs to be externally connected to a
5~12V DC regulated power supply;
(2) Fix the radar SR-PA24R with 4 M3 screws.

3 Radar Parameter
Table 1 Parameter
Parameter
Specification
Transmitting frequency
24.00-24.20GHZ
Detection range
≥100m
Measurement accuracy

0.02m
Beam wave width
Azimuth28°，Elevation 18°
Interface
UART
Working voltage
5~12VDC
Consumption
1.5W(typical value)
Working Temperature
-40~80℃
Weight
120g
Dimension
130x70x14.5mm(LxWxH)
4 Quick use steps
4.1 Pin Definition
SR-PA24R Interface pin definitions, as shown in Table 2:
Table 2 SR-PA24R pin definition
Pin
Definition
Range
1
VCC(red)
5~20V DC
2
GND(black)
-
3
UART_RX (white)
TTL 3.3V DC
4
UART_TX (yellow)
TTL 3.3VDC
4.2 Test
Use USB to serial device to connect the output serial port, connect the USB port to
the PC serial port debugging assistant software, the radar output data will be displayed.

For details, please refer to the serial data protocol description. The test tools or
software is shown in the following table:
Table 3 Product test tool
No
Device
Qty
1
SR-PA24R
1
2
PC
1
3
USB to TTL adapter
1
4
5V or12Vpower adapter
1
5
Serial port debugging
assistant software
1
Note: The TX and RX pins of the USB to TTL adapter and the TX and RX pins of the SR-PA24R
Radar need to be cross-connected.
5Data Parsing
The 24G radar altimeter outputs data through the serial port, 115200bps, 8N1, no
data no output, the specific protocol format is as follows:
Table 4 Data parsing
Data type
Number of
bytes
Description
Header byte
1Btyes
static，0x48
Height data
2Btyes
The lower 8 bits are in the front, the higher 8 bits are in
the back; the unit is cm; the signed integer is used, and
the highest bit of each byte should be discarded when
acquiring data;
Radar altimeter 3-byte protocol: 0x48, DataL, DataH; In order to adapt to open source
flight control, the actual distance is calculated in the following formula:
actual distance （cm）= [(DataH&0x7F)*128 + (DataL&0x7F) ]*2.5。
6 Open source platform
The SR-PA24R is compatible with the open source flight control altimeter protocol

and can be directly connected to the general open source flight control platform. The
following is a brief description of the integrated application settings of the SR-PA24R
on the APM flight control platform.
Flight Control Hardware: PixhawkV3
Flight Control Software: ArduPilot Copter 3.5.5
Ground station software: MissionPlanner 1.3.62
6.1 Radar installation and wiring
The radar serial port is connected to the pixhawk TELEM2 interface. The radar power
supply needs to be powered separately. The interface definition is as follows:
Pic 2 pixhawk TELEM2 interface definition
For the installation method, please refer to the following figure (taking the D600
M600 Pro flight control platform as an example):

Pic 3 Radar Installation reference
6.2 MissionPlanner Ground station for flight control parameter
setting
（1）Set the TELEM2 serial port parameters, the SERIAL2 baud rate is set to
115200bit/s (SERIAL2_BAUD is set to 115), and the communication protocol is set
to Lidar (SERIAL2_PROTOCOL is set to 9), as shown in the following figure:

Pic 4set TELEM2 serial port parameter
（2）Set the radar library parameters, set the radar type to ulanding (RNGFND_TYPE is set to
11), and set the radar installation direction to vertical downward (RNGFND_ORIENT is set to 25),
as shown in the following figure:
Pic 5 Set radar library parameter
Finish set above parameters and save the setting, then restart the flight control to test
the radar outdoors.
7 FAQ
（1）What is the angular accuracy of the SR-PA24R?
The SR-PA24R is a 24GHz radar sensor is with one transmitter one reciever
antenna, which can not be used to measure the angle of the target.
（2）When SR-PA24R facing vegetation and ground/water surface when measuring
height, which target will be subject to it?
The SR-PA24R is a millimeter-wave radar with high range accuracy developed by our
company. In practice, the height should be divided. If the height is less than 3m, the
airflow under the aircraft is large and the vegetation is likely to be blown away. The

reference point is the ground or the water surface. If the aircraft fly above 5m, the
airflow will not affect the vegetation below. If the vegetation density is high, then the
detected height will be the distance from vegetation to the aircraft.