Here’s the material you’ll need for this project.

Radio Modules

This is the most important part of the project, and many different radio modules can be used with ULRS.

All modules are compatible, you can for example combine an OrangeRX 1W TX with a DIY ULRS RX module.

All the modules can be used as RX or as TX, regardless of their initial function or naming. Some modules have the exact form factor and connector to be plugged into the RC transmitter, which is practical, but they can as well be used as RX in the plane.

DIY Modules

ULRS Minis

ULRS Mini are 10 different boards made for Ultimate LRS, that you can easily DIY.

All based on the same ULRS Mini reference schematic, these modules have been created by ULRS users. Some of them are really easy to build, and all of them are more reliable and often cheaper than OrangeRX or Wolfbox modules.

Enjoy the satisfaction to build your own equipment !

Click here to see all the ULRS Mini modules.

Pros

• High reliability : ULRS Mini solves all issues of other modules. The design includes many protection resistors. Impossible to destroy for example by shorting RX/TX pins, many other protections are included.
• Maximum power
• Choice between 10 different DIY modules
• Cheap to build
• Fun to build
• Schematic provided
• PCBs available
• Plugs directly into transmitter
• Some modules include USB connectivity, no need for FTDI adapter
• Simple to build : most modules are based on an Arduino pro mini which already includes about 17 SMD components. So there’s only to solder the Arduino, the RFM module and a few other components to get it done.

Cons

• None

Ready-to-fly modules

OrangeRX modules

OrangeRX modules are produced by Hobbyking.

Remark : OrangeRX is the brand name, which contain both RX and TX module. Every OrangeRX module (TX or RX) contains a similar transceiver chip, so you can use two “OrangeRX 1W TX” to make a bidirectional 1W link.

OrangeRX 1W TX module

They directly plug into JR, FrSky Taranis RC transmitters.

• Link to the product on Hobbyking

Pros

• Ready to fly
• Switching power supply is a quality component protected against polarity mistakes, short circuit, over current, and supports up to 36V input.
• Good looking case
• Fits into transmitter
• CE marking, mandatory for Europe. Notice that most other LRS systems don’t have this marking.
• Good results since years

Cons

• Runs at 3.3V which reduces the power. A mod exists to make it run at 5V.
• The weak point is the UFL cable to the antenna, which sould be replaced immediately
• Provided antenna is of poor quality and must be replaced. In any case monopole antennas aren’t recommended. Check some suggested antennas here.

OrangeRX modules with integrated Bluetooth

• Link to the product on Hobbyking site

Some hardware modifications are required to use the RX module with ULRS. Please check this page for more information.

Pros

• Both modules have an RFM23BP (1W) inside.
• They have a shield around the RFM23BP

• The TX has a Bluetooth module inside the case

• Apart from the Bluetooth module, the TX is a regular OrangeRX 1W TX.
• Directly plugs into the transmitter.
• Small form-factor of the RX, one of the smallest designs that still provides an RFM23BP chip.

• TX module has the high quality switching regulator of OrangeRX 1W modules
• RX modules has also a switching regulator, which is a good point : usually RX modules only have a linear regulator which would warm up with 1W power.

Cons

• Hardware modifications are required for the RX : check this page for more information.
• No bootloader included on the RX : use of an USBasp programmer is mandatory.
• Some Bluetooth configuration is required.

Wolfbox

• Link to product on Banggood
• Link to product on GoodLuckBuy

Very similar to OrangeRX, but have their own switching power supply with some discrete components rather than a all in one module as in OrangeRX. Difficult to say which is the best, but I’d be surprized if the Wolfbox does accept 36V input.

Should you need to reflash the bootloader on a Wolfbox module, which has no JTAG header, you can find instructions here.

Pros

• The RFM module is enclosed in a metal shield.
• Directly plugs into the transmitter.
• Slight improvement for the 100mW module, where it’s impossible to destruct the module by sending 5V on the serial port VCC pin. But flying with 100mW isn’t recommended.

Cons

• The serial connector doesn’t match directly an FTDI adapter (different pinout).
• Sold as 1W+100mW combo.
• Bootloader runs at 115200 bauds, which doesn’t play nice with some FTDI adapters.

Flight Controller

APM

Original APM from one of these retailers or the HobbyKing clone.

Pixhawk

You can of course use Pixhawk as flight controller.

Other

Almost all other flight controllers are supported too : ULRS behaves as a transparent link for telemetry.

FTDI cable

Here are some examples.

Next step

You’ve got everything ? Good !

Now let’s set up the hardware.