Ultimate Guide to Drone Module Selection

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Drones

The most important characteristic for drones is their weight.

Weight: 6.2 grams

For the lightest drones, weight is the most crucial factor. If you take the ELT0150 board weighing 4 grams and the ELT0176 antenna weighing 2.2 grams, you will get an ultra-light and affordable solution weighing 6.2 grams with very low power consumption due to the use of the MAX-M10S receiver. The reception quality of this antenna can be improved with a homemade ground plane. The board uses a 6-pin JST SH connector and has I2C and UART interfaces at TTL levels. To receive Beidou signals, you need to switch the receiver to the B1C signal instead of B1I.

Weight: 7.5 grams

The most suitable board is the ELT0169 with the SAM-M10Q receiver. The board interfaces include I2C and UART at TTL levels, and it weighs 7.5 grams with a 6-pin JST SH connector. There is an alternative board of similar weight, the ELT0020 with the MAX-M8Q receiver, but they have almost three times higher power consumption and cannot receive Beidou signals. Additionally, the ELT0020 does not support I2C and is significantly more expensive. The advantage of this option is its very low weight, but the drawback is the poor solution quality due to the use of a small patch antenna without a ground plane.

Weight: 14 grams, Pixhawk

For the Pixhawk autopilot, a board with a magnetic compass is required. The lightest board with the LIS3MSL magnetic compass is the ELT0102 with the M9N receiver, weighing 14 grams. It has a mini USB connector and 6 contacts with a UART interface for the receiver and an I2C interface for the LIS3MSL compass. The advantage is its low weight, but the drawback is its very small groundplane, which affects reception quality.
The ELT0099 board is a slightly improved version of the ELT0102, weighing 29 grams. It has the same connectors and interfaces, but both the antenna and ground plane are larger, resulting in better reception quality. The ELT0024 board weighing 16 grams, with the MAX-M8Q receiver, is chosen mainly for its small size (25x25 mm), but it does not have a mini USB connector. Due to its minimal size, it has worse reception than the 14-gram ELT0102, and due to the outdated receiver, it can receive only 3 satellite systems simultaneously, while the M9N can receive all 4 major satellite systems simultaneously. Unfortunately, there are no similar boards for M9V and M10S receivers.

Weight 18 grams

For heavier drones, there is a lightweight Helix antenna ELT0124 for L1 frequency weighing 11 grams. This antenna screws onto an SMA connector and is held solely on the connector, so it is only suitable for boards with this connector (see section "Boards with SMA Connector") assembled on single-frequency receivers. The most optimal receiver is the NEO-M9V. The advantage of this receiver is a solution rate of up to 50 times per second and the ability to obtain coordinates with some accuracy without satellite reception, for example, when flying under bridges, due to UDR technology. The best board for M9V is the ELT0165 (weight: 6.8 grams) with 12 contacts and interfaces such as UART, I2C, SPI, and USB. Slightly heavier is the ELT0173 board weighing 9 grams, with a mini USB connector and 6 contacts with I2C and UART. The second option is the MAX-M10S receiver. The advantage of this receiver is low power consumption. The ELT0151 board weighs 7 grams and has a JST SH connector with I2C and UART interfaces.

Weight 18 grams, Ardupilot

Since Ardupilot requires SPI, the lightest set for it is the ELT0124 and ELT0165 described above. The advantages are a 50 Hz solution rate and UDR.

Weight 29 grams and RTK

The set for receiving with centimeter accuracy (RTK) at a distance of up to 50 km from the base station (see "RTK and PPP") is based on the ELT0014 (or ELT0014W) antenna for the L1/L2b range weighing 20 grams and the ZED-F9P receiver. This antenna screws onto an SMA connector and is held solely on the connector, so it is only suitable for boards with this connector (see section "Boards with SMA Connector") assembled on a dual-frequency receiver ZED-F9P. The optimal set is the ELT0091 bundle, consisting of the ELT0014 antenna and the ELT0087 board (weight: 9 grams) with mini USB and JST SH connectors on 12 contacts with interfaces such as I2C, SPI, and 2 UART. The ELT0092 board differs only in having 14 contacts instead of connectors, and the ELT0112 board is slightly heavier (11 grams) and, in addition to 14 contacts, has a mini USB connector. The best of them is the ELT0087 with an extremely low noise level stabilizer.

To improve reception, you can use a higher quality but more expensive and heavier ELT0121 antenna (ELT0121W) weighing 35 grams or a slightly more modest ELT0170 antenna weighing 32 grams. Another option is the ELT0152 corner antenna weighing 28 grams.

Weight 40 grams, RTK during roll and multipath protection

There is a cross-dipole antenna ELT0148 weighing 31 grams, which effectively filters out reflected signals and interference. Based on it, an RTK system is developed for drones flying in close proximity to buildings and mountains. The same boards as in the previous section ("Weight 29 grams and RTK") are used, so it is best to use ELT0087.

Weight 46 grams and EMI protection

On larger drones, there is a problem of protecting the receiver from electromagnetic interference (EMI) generated by powerful motors. For such protection, special smart antennas are made, where the receiver and antenna amplifier are enclosed in a Faraday cage.

The optimal setup for this situation is the ELT0174 board with the M9V receiver, weighing 46 grams. The advantage of this receiver is a solution rate of up to 50 times per second and the ability to obtain coordinates with some accuracy without satellite reception (for example, when flying under bridges) due to UDR technology. The connectors are mini-USB and 4 contacts with a UART interface.

Slightly worse reception is achieved with the very similar ELT0175, which has the same receiver and weight but a smaller antenna size and is slightly cheaper.

For those who do not need a solution rate of 50 times per second and obtaining coordinates without satellite reception (UDR), there are cheaper versions with the M9N receiver:

ELT0105 - analog of ELT0174

ELT010 - analog of ELT0175

Weight 51 grams, Pixhawk, EMI and RFI protection

In some situations, it is necessary to protect not only from EMI but also from radio frequency interference (RFI). The thing is that antennas also receive and amplify out-of-band signals. If the signal is strong enough to overload the amplifier, satellite reception is disrupted. This can happen when flying near satellite communication antennas, television towers and repeaters, and cellular base stations. And the most common case is when the transmitting antenna of the drone's own transmitter is too close.

In this class, there are three boards with different receivers and weights. If not specified additionally, the connectors are mini-USB, and there are 6 contacts with I2C outputs for the magnetometer and UART for the receiver.

The ELT0045 board (weight 51 grams) contains the M8N receiver, while the ELT0104 (weight 79 grams) and ELT0137 (weight 114 grams) boards have the M9N receiver. The ELT0045 board with the M8N receiver performs the worst, as this receiver cannot receive all 4 GNSS systems simultaneously, but it is the lightest and cheapest option. The ELT0137 board provides the best reception quality, but it is the heaviest and most expensive.

Weight 56 grams, Pixhawk, Ardupilot, RTK, and EMI protection

To use with Pixhawk for centimeter-level accuracy (RTK) up to 50 km from the base station (see "RTK and PPP" section), you will need the ZED-F9P receiver and an L1/L2b frequency range antenna. These functions are available on two boards - ELT0089 (weighing 56 grams) and ELT0118 (weighing 66 grams). Both boards feature EMI protection and excellent power filtering. The connectors on these boards are the same: mini-USB, JST SH with 4 contacts for I2C from the LIS3MDL magnetometer, and JST SH with 12 contacts containing two UART and I2C or one UART and SPI (to enable SPI, contacts D_SEL need to be shorted).

Due to its greater phase center stability, ELT0089 provides the best solution quality. It is also lighter and slightly cheaper.

Fixed-wing drones

For heavy fixed-wing drones, a system consisting of two boards is used, providing both position and heading (when installing both antennas along the aircraft's longitudinal axis). For this, an F9P module is needed for the base receiver and an F9P or F9H module for the heading receiver.

The base receiver module is described in the "Weight 56 grams, Pixhawk, Ardupilot, RTK, and EMI protection" section. So, until there is a smart-ready F9H (equivalent to ELT0089), two of these modules are required.

Stratux ADS-B

For receiving ADS-B signals on aircraft, Stratux ADS-B is used. It is recommended to use the ELT0166 module with the M9V receiver. This receiver allows obtaining coordinates for a certain period without satellite reception, for example, when flying over a GNSS signal interference zone. If this option is not important, a slightly cheaper ELT0114 module with the M9N receiver can be used.

© Eltehs SIA 2023