Yes! Tersus PPK solution is platform independent, which does not just mean that it can go from your fixed wing UAV to your Multi-rotor but also means that it operates independently of your flight controller. In fact, there is no connection between the Tersus system and your flight controller, unless you are using your flight controller to trigger event mark in Tersus system or use Tersus system for navigation purpose. So whether you are using an APM, Pixhawk, NAZA, WOOKONG, MICROPILOT, Mikrokopter, Microdrone, or any other flight controller, Tersus PPK solution will still work!
Tersus BX-series GNSS OEM boards and receivers are cost-efficient solutions for obtaining raw GNSS measurements and centimeter-level precision positioning. Those boards/receivers include BX316, BX316R, BX316D, BX306, BX306Z and BX305.All BX-series OEM boards offer multi-constellation (GPS, GLONASS, and BeiDou) and dual-frequency tracking capabilities, which improve the availability, continuity and reliability of RTK solutions in challenging environments.
All BX316, BX316R, BX316D, BX306, BX306Z and BX305 support multi-constellation (GPS, GLONASS, and BeiDou) which are designed to deliver centimeter precision positioning and accurate raw measurement output.
The differences among those BX GNSS OEM boars are listed below.
● The BX306 is capable of accepting/sending NovAtel-compatible command and logging protocol, and are pin-to-pin compatible with OEM615 receivers. Using the BX306 provides efficient pathways for rapid delivery of GNSS-capable products to markets.
● The BX306Z has flexible interfaces and is pin-to-pin compatible with the Trimble BD970 GNSS system. It is designed for take-up by original equipment manufacturers and system integrators.
● The BX316 commands and logging are compatible with NovAtel protocols. On-board Ethernet, USB, LVTTL, RS232, CAN, PPS and Event Mark are supported. An on-board SD card (up to 32GB) supports data collection.
● The BX316R is a multi-GNSS, post processing kinematic (PPK) board which supports raw measurement output from two antennas. An external SD card (up to 32G) enables developers and end-users to record data for post processing.
● The BX316D uses common interfaces, logging and command formats, which can be configured for compatibility with major OEM boards. It is pin-to-pin compatible with NovAtel OEM617D.
The Tersus BX GNSS OEM boards can output four types of solutions, including single point position, DGPS, RTK float, and RTK fixed. The BX boards can automatically determine the solution type according to the observation conditions and data link status. Take BX316 GNSS RTK OEM board for example, the positioning precision details are listed below.
●Standard Positioning Accuracy
- Horizontal(RMS): 1.5m
- Vertical(RMS): 3.0m
●RTK Positioning Accuracy
- Horizontal(RMS): 10mm+1ppm
- Vertical(RMS): 15mm+1ppm
- C/A Code(zenith direction): 10cm
- P Code(zenith direction): 10cm
- Carrier Phase(zenith direction): 1mm
- Heading Accuracy 1m Baseline(RMS): 0.1°
Tersus BX GNSS OEM boards support 20Hz raw measurements. For position solution, 20Hz is supported for three constellations (GPS+GLONASS+BDS) and 10Hz is supported for two constellations (GPS+GLO or GPS+BDS).
Yes. Tersus BX GNSS OEM boards support raw data logging. You can input
log rangeb ontime 1 [to save the raw data to the computer that the receiver is communicating with]
log file rangeb ontime 1 [to save raw data to the SD card or the EMMC card]
Yes. The following loggings must be saved from the base and the rover respectively for PPK application.
log rangeb ontime 1 [save raw measurements at 1Hz]
log gpsephemb ontime 30 [save GPS ephemeris data every 30 seconds]
log bdsephemerisb ontime 30 [save BDS ephemeris data every 30 seconds]
log gloephemerisb ontime 30 [save GLONASS ephemeris data every 30 seconds]
Tersus BX GNSS OEM boards support GPS, GLONASS and BeiDou.
Tersus BX GNSS OEM boards don’t support Galileo at this moment. Galileo will be supported by Q3, 2018.
Yes. BX316 and BX316D GNSS OEM boards support heading output.
Yes. To set a Tersus BX GNSS OEM board/receiver as a base station, the position of the antenna must be known. The following is a typical config for a base. (Assume RTK corrections are outputted to COM2)
fix position latitude longitude Mean-Sea-Level height
log com2 rtcm1074 ontime 1
log com2 rtcm1084 ontime 1
log com2 rtcm1124 ontime 1
log com2 rtcm1005 ontime 10
The following proposals are provided:
●If a nearby CORS station is available, config the receiver as a rover to receive the CORS' RTK corrections, then the accurate position will be got.
●If you have a receiver supporting L-band, it can output cm-level position after the solution is converged.
●You can collect raw measurements for some time with the receiver; send the data to OPUS to get the accurate position.
Tersus doesn't provide any post processing software. RTKLIB is recommended for post processing, it's free and open sourced, and its performance is OK, so it's popular. The link is http://www.rtklib.com/prog/rtklib_2.4.2_bin.zip
You can convert the collection file to RINEX format with Tersus RINEX Converter. Please note, rangeb or rangecmpb loggings must be included in the file, or no RINEX file will be created.
It depends on what loggings you're saving. If a binary format is output, then a *.bin file will be created. If NMEA loggings are output, then a *.nmea file will be created. If the RTK corrections from the base is saved, then a *.passcom file will be created.
Please refer to the typical power for BX GNSS OEM boards below.
The BX GNSS OEM boards have performance requirements (such as ripple, P-P value) for the input power, so if an unqualified power is used, the receiver may not work properly or even worse, the receiver has risk to be damaged. So please ensure qualified power is used.
The BX GNSS OEM boards/receivers have two serial ports, so any serial tool can be used to communicate with the BX receivers. Tersus GNSS Center is recommended since it's a graphic tool and has some features just for the BX GNSS OEM boards/receivers.
Being a RTK receiver, the BX306 can provide cm-level positioning after RTK corrections are received and it can be used in a mobile mapping system. But whether GCPs can be omitted is not governed by BX306 performance alone. The following factors are also crucial to mapping systems:
●The performance of the camera.
●The latency of the control system.
●The camera’s attitude accuracy.
●The scale of the mapping.
According to our experience, GCPs are necessary for large scale mapping, for example, 1000:1 and 500:1.
The Tersus GNSS OEM boards support RTCM 2.x/3.x/CMR/CMR+. Other communicated differential messages include correction message, correction data and differential data.
In open sky environment, the initialization time for different first fixed solutions is listed as below.
- Single point positioning <40 seconds
- RTK positioning<10 seconds
- Single point positioning <20 seconds
- RTK positioning<10 seconds
There is no extra configuration necessary for receiving different RTCM messages. The Tersus BX GNSS OEM boards can automatically recognize RTCM2.X or 3.X. There is no significant difference between the versions.
In theory, there are two inputs to a rover, the satellites signals from the antenna and corrections from the base. So if the rover can’t get fixed solution, please check the following:
●Does the antenna have good view of sky and is the communications connectivity reliable?
●Is the power to the antenna is OK?
●Have the RTK corrections from the base been transmitted successfully?
●The corrections datalink is OK.
●The baud rate and the receive type of the rover’s port are correct.
The possible reasons are:
●The receiver’s baud rate is not the same as the computer’s port.
●The USB adapter driver has not installed correctly.
●The GND signal of the adapter is not reliably connected to the GND of the receiver.
●The driver for the USB adapter is not installed successfully.
●The receiver’s baud rate is not the same as the computer's port.
●The receiver port’s Tx/Rx type is not correct.
●The cable connection is not reliable.
The BX receiver has a serial port, so in theory, any serial tool can be used to communicate with it, for example, Hyper-terminal, UarTerm or SSCOM32. It is recommended that the Tersus GNSS Centre, a graphic serial tool, is used to communicate with BX receivers.
The Tersus RINEX Converter supports raw measurement data and RTCM data. This data can be converted to RINEX 2.10 or RINEX 3.02 by using the Tersus RINEX Converter.
The BT120 Bluetooth module cannot pair with an iPhone. It can only pair with Android smart phones.
●The Bluetooth module is not powered correctly. It may be necessary to power cycle the BX receiver.
●The Bluetooth in a smartphone can’t be paired successfully with the Bluetooth module. The module can only communicate with an Android system.
●The baud rate of the Bluetooth is 115200, so ensure the receiver’s serial port has also been configured to 115200 baud rate.
Tersus offers four kinds of radio modules.
|915MHz small radio||895-935||0.5||0.3|
|433MHz small radio||403-470||0.5||0.3|
915MHz Eagle radio
|RS05R radio||410-470||0.5, 1||5|
It may be caused by following reasons:
●A fixed coordinate must be defined for the BX receiver before the RTCM output can be sent. Therefore, use the Fix Position command (see Tersus GNSS Command & Log Reference document) to fix the coordinate first.
●Check the Interfacemode. If the target serial port is not in right mode, it may not output RTCM properly. Use the Interfacemode command (see Tersus GNSS Log & Command Reference document) to set the serial mode.
It can be caused by following reasons:
●Check the power supply. The BX306 board power consumption is about 3W. Note that although a Pixhawk controller can supply power, its output power capability is far less than 3W, in which case the BX306 must be powered by an external power source. A voltage convertor is recommended to convert 12V battery power output 5V for connection to a BX306 board.
●Please check the baud rate settings within the Mission Planner. It cannot be recognized if incorrect baud rate is used. By default, the baud rate of BX306 COM1 port is 115200 bps.
●Please check the NMEA output. The Mission Planner requires GPS sensors outputs, i.e., NMEA GGA sentence, RMC sentence and VTG sentence, at 5Hz. Missing VTG sentences or low update rates may cause recognition failures.
●Check the NMEA talker. Note that the Pixhawk can only recognize the NMEA sentence with GP NMEA talker. Incorrect NMEA talker may cause failure.