FAQs

Can the Bluetooth module(BT120) be paired with iPhone?

No, the Bluetooth module can't pair with iPhone; it can only pair with Android smart phone.

What's the radio range of the radio module?

There are two kinds of radio modules, one is 915Mhz (US) and the other is 433Mhz (Europe). The radio range for 915Mhz module is 895 -935MHz, and is 403 - 470 MHz for 433MHz module.

Can Precis-BX306 work well for aerial photogrammetry with UAV without the need for ground control points (GCPs)? Do I need a specific camera to work or any camera?

Yes, the following solution can be used to replace the GCPs.

You can setup a base with our Precis-BX306, and then transmit RTK corrections from the base. After the corrections are received, it will output accurate (cm-level) positioning and heading info. In the application of aerial photogrammetry with UAV, after the camera take a picture, it will send a pulse from the PC (Prontor-Compur connection) port to the receiver, the accurate position (cm-level) will be saved. The photos and their positions will be input to the mapping software (eg, PIX4D or Agsoft) to get an accurate map.

No specific camera is needed; you can use any camera which has a PC (Prontor-Compur connection) port. And the synchronization between the shutters to the flash must be enabled. When the camera is taking a photo, a pulse is sent to the receiver through the PC port. The exact time when the photo is taken will be saved for post-processing.

Can Precis systems log raw observation data for post-processing?

Yes. All Precis boards (BX305 and BX316) support raw observation data logging. They support an external data logger. The logged binary observation data can be converted into Rinex format with the Tersus Rinex Converter..

Is the max update rate 10Hz for all constellations or only for GPS?

We don't have a command to request all settings, but you can type “log loglist” to check all logging information. For more details regarding commands, please refer to Chapter 3: Commands Description in the Precis-BX305 user guide.

Can Precis boards connect to Pixhawk?

Yes. The Precis module can connect to Pixhawk. The details can be found in the User Guide. You can find it and download freely in our website.

Is it possible to change the baud rate or configure other settings of the supplied UHF radios in the Precis bundle kit?

Our radio module is fully compatible with 3DR radio products, so you can configure them with open-source 3DR radio configuration tools. However, configuring the radio module is not recommended, since it may cause communication problems.

Which RTCM version do you support (for using network RTK)?

We support RTCM 2.X and 3.2. The details of the supported RTCM can be found in the Precis-BX305 user guide. The RTCM 2.X only supports GPS and GLONASS. If you want to use network RTK, you may need a serial modem to connect the board to the Internet, as the board does not have a built-in network access feature.

Is the max update rate 10 Hz for all constellations or only of GPS?

The solution output is up to 20Hz and the observation output is 5Hz at maximum.

Is there any configuration required for receiving different forms of RTCM?

here is no extra configuration necessary for receiving different RTCM. The Precis board can automatically recognize RTCM2.X or 3.X. There is no significant difference between the versions.

Do you have a dual antenna GPS unit with a heading functionality?

Yes. Our next-generation product Precis-BX316 supports a dual antenna heading feature in one unit. Precis-BX316 supports GPS L1L2/BDS B1B2/GLONASS G1G2 with a GPS L1L2 heading mode. In addition, it supports up to 20Hz RTK solution output and an onboard SD card for raw data logging, which is key for post-process and data analysis.

A camera shutter synchronization feature for aerial mapping applications is included as well. The Precis-BX316 supports heading with a dual antenna input, which provides accurate yaw and pitch angles of a moving platform.

Will Precis boards output using a regular RS232 serial cable to a PC, including 2 x Picoblade UART cables and 2 x TTL-USB? Is the serial output only compatible with microcontrollers, or can it be used directly with a PC?

Our port is a TTL level serial port, not RS232 level. The major difference between these two ports is the voltage level. The TTL level requires a lower voltage than RS232, but it is fully compatible with PC and microcontroller. The TTL-USB connector can be connected to a PC directly.

What is the positioning precision of the Precis-BX305?

Precis-BX305 can output four types of solutions: single point position, DGPS, RTK float, and RTK fixed. Detailed precision can be found in the datasheet on our website. The board can automatically determine the solution type according to observation conditions and data link status.

How long does it take for Precis to get its first fixed solution?

Typically it takes a few seconds, but it is observing condition-dependent.

How do I connect to a base/reference station?

Precis-BX305 board can connect to a reference station via radio or Internet. In the case of radio, you need an external radio module for the data link. For Internet, you need an external Bluetooth module to connect to your phone.

How do I connect to the Precis with my laptop?

The Precis-BX305 can connect to a laptop with a Tersus USB connector, which is distributed along with the board. We also have Tersus GNSS Center software for display and board configuration.

What kind of differential message protocol does Precis support?

Currently, the Precis-BX305 supports RTCM v2, RTCM v3, GPS, GLONASS, and BDS observations are delivered in RTCM MSM message type.

Does RTCM have to be input on COM2 or can it be received on COM1? Can RTCM be received on the same port NMEA is being output on?

Yes.

Can Precis connect the rover to a network CORS instead of a local reference station?

Precis-BX305 board does not directly support NTRIP protocol, but other customers use a cell phone as a transceiver to connect to CORS. We do have Bluetooth utilities for cellphone connection, and an open-source app can help your cellphone connect to the CORS network.

Can I use an NTRIP setup? (The UAV as a "rover" connected to a network receiving corrections)?

Precis-BX305 board does not support network function, but we provide an external Bluetooth module, which can be used to connect with the NTRIP client running on a cell phone. With NTRIP, you can connect the Precis-BX305 board to the CORS network.

What constellation does Precis support? Do the Precis boards work simultaneously with all constellations or GPS + GLONASS/GPS + BEIDOU?

The Precis board supports GPS, GLONASS, and BeiDou. Multi-constellation provides better positioning performance in challenging environments, such as cities, canyons, and canopies. The Precis-BX305 board supports three constellations and six frequency signals simultaneously.

Is there any way to retrieve the base fix position that has been entered into the Precis-BX305? (Can we see what coordinates and height we have set the base to be?)

Yes. You can find this in the GGA sentences. You can log a GGA sentence, and the coordinate is what you have set. The fixed coordinate has its quality indicator as 7.

How do Precis boards provide synchronization with a camera shutter?

It depends on which solution (which Precis RTK board) you are using. For the Precis-BX305, it supports PPS output, which is useful in shuttle synchronization. For the Precis-BX316, it can work with an event marker.

What is the principle of GNSS positioning?

Satellite-based positioning relies on measuring the distance between a satellite and receivers. With known satellite positions and the measured distance between the satellite and receiver, the coordinate of the receiver can be calculated. However, the electromagnetic signals emitted by satellites are disrupted by atmosphere and clock errors, which degrade GNSS positioning accuracy.

There are two types of positioning modes; one is point position and the other is relative position. Point positioning includes standard point positioning (SPP) and precise point positioning (PPP). Their major difference is whether they use carrier phase observation.

Relative positioning also includes two types: DGPS and RTK. Their difference is that the latter uses carrier phase observation as well. Relative positioning cancels most error sources in distance measurement by making a difference between two receivers, so it is simpler and more reliable, but it only measures relative position. In practice, the coordinate of the reference receiver is fixed as known.