Smart Falconry Telemetry - Small low power MCU controlled RF telemetry transceiver for tracking small wildlife and birds of prey on the wing.

Falconry Telemetry, from concept to prototyping to reality.

Think" Falconry telemetry transmitters are generally a large investment for falconers. This is because the market for ultra light weight transmitters that are powerful yet consume minimal current is relatively small. It also takes a lot of engineering to create a powerful transmitter in a micro package light enough to attach to a small bird of prey. The worst that can happen to a falconer is when the bird of prey flies away, cannot be tracked right away because of geography (think flying over a large river, etc.) or the time of day (with a setting sun) and the transmitter battery is starting to get low. Without an active transmitter the chance of locating the bird is lost as they can fly any direction any time. Not only is the bird lost, but also the telemetry transmitter, a double sour deal. After seeing this happen much to often, the time was ripe to come up with cost effective and efficient alternative with adaptable options for different operational modes.

Research Looking into using discreet SMD components which are easy for creating very small size circuits using a few transistors, capacitors and resistors soon got dropped. The reasons are, it uses to much energy, continually consuming current, even when not transmitting and the frequency stability is not acceptable. The second idea was to use a MCU with a micro small xtal transmitter module. A proof of concept using a SEEED MCU with a (common) miniature fixed frequency module soon became obsolete as the telemetry receiver at Falconcrest falconry can only receive 433.1XX MHz.

A low cost to preferably no cost project

With no budget it meant using bits and pieces lying around and thinking twice about ordering any components or having anything constructed. A tall order for a micro transmitter. I am thinking of making this an open source project should others be interested on using and improving this wild life telemetry design.

SEEED MCU Prototype

SEEED telemetry POC

Initial proof of concept, small, stable and powerful, but fixed frequency bound. Because of this, any garage door opener will trigger a false signal, unless roaming in the Scottish Highlands. Thus NOGO.

MCU & RF Module Test

Telemetry prototype

Using an ATTINY85 to control a compact Silicon Labs transceiver module. Brilliant, just not enough IO pins! So this design will remain a basic TX only module. Operated for more than 13 days on a new cr2032 lithium button cell. Need more feature options (GPS: big +, remote configuration (power,TOD), emergency APRS?

The right stuff

telemetry tranceiver

Testing potential transceivers for accuracy and stability. The Si4463 seems a winner.

Product development

Telemetry front

Design V1.0 ready for initial manufacturing

Functional specifications, research,design and development

Requiremnts The 'must have' requirements were: 1. small, 2. lightweight, 3. long range transmitter, 4. long operational period on a limited lifespan battery, 5: Terranean weather proof, 6: Animal vandal proof. That is quite a challenge as some requirements have a lot of impact on other requirements. The way to tackle this was to look at the possibility of making it really dynamic by allowing multiple implementation like using different interchangeable battery types and providing a means to instruct the transmitter which mode you want, like long battery life, or high power transmission. Thus a micro radio transceiver and a means to control it was needed.

Research Searching for a powerful very diverse micro RF transceiver module, not like the fixed frequency unit I first tested, I came across the Silicon Labs Si4463 SMD chip, the spec sheet showed a +20db transmitter with a frequency range of 142 to 1050 MHz. Just what was needed to service nearly all falconry telemetry receiver types frequency ranges as well as powerful enough to get excellent transmission range. It supports (tested) stable frequency transmissions on a variable power supply (battery being used) and supports 'sleep mode' where it uses virtually no power at all. Proof of concept showed that indeed, this very small RF transceiver although initially complex to program and setup could run on a CR2023 button cell at full power using on off keying at one second intervals for nearly 2 weeks (309 hours).

Electronics Now for the telemetry controller. Needed was a low power micro MCU AVR that could be used to setup and program the radio and also be smart in how it operated with the ability to also go into sleep mode and consume virtually no power. I used a SEEED XIAO for the initial proof of context and was wondering if I could use an Atmel ATTINY85 so going minimalistic, gave it a successful try, however I ran out of IO pins as we needed a way to switch it all on when in use and off when in storage via a hall magnetic sensor as switch. This meant we needed to reprogram an IO pin to act as power switch sensor when the radio was not transmitting and quickly reprogram it again when it was time to transmit. A way to indicate whether it was on or off via a LED also needed a separate IO pin. After getting the IO pin interupt dance routines in place, the specs were changed, so this design will remain a basic TX only falconry telemetry transmitter. The 'what if' and 'how about' were laid on the table.

With time came new ideas to make the project smarter (and bigger). First idea was to monitor battery charge and take appropriate action. This can also be done with the ATTINY, but not comprehensively with complex rechargeable batteries. Then the word GPS was mentioned as an option which came with many possibilities and benefits, but also some drawbacks. Last but not least, as we are using a transceiver that can transmit and also receive, the option to remotely send instructions to the telemetry unit to change settings (like GPS On/Off, low or high power) while it is in operation was put on the list. Not to forsake the concept of a simple telemetry transmitter, an expandable modular approach was adopted. All that needed to change was the MCU, as it could not potentially service the new needs. The ATTINY85 got replaced by a bigger brother, the ATMEGA328 now we have enough IO pins, can accommodate GPS, do accurate battery management, implement two way RF communication and also consider it being used as APRS transmitter (if operated by a radio amateur license holder) for wide area geo-location in the future.

New concept (May 2022) for long distance and 'odd' situation tracking. Fact: a bird flying at 'high' altitude is easy to track from the ground in line of sight. Fact: a bird on the ground is difficult to track from the ground because of obstacles (buildings, natural growth, distance, rf echo's, etc.). Challenge: can we reverse this and send a drone into the sky with a tranceiver to scan the surface below for transmissions, interact with the telemetry transponder and relay this to a base station. Have not even got the components I need for the simple telemetry transponder and already I know we need asmart telemetry receiver as well. Work to done while we wait.

Basic Transmitter design back

PCB Design back

Size: 17.0 x 17.3 mm

Basic Transmitter Controller design front

PCB Design front

Wide SOIC for in-circuit programming

Basic Transmitter Controller PCB back

PCB back

Basic Transmitter Controller PCB front

PCB front

Smart Transceiver PCB front

Falconry Telemetry PCB front

PCB design front

In-line or preprogrammed

Falconry Telemetry out of circuit programmer

Out of circuit programmer. Useful for when space on the final product does not allow room for external programming ability.

Smart PCB design front

Telemetry tranceiver components front

PCB components front

Smart PCB design back

Telemetry tranceiver components back

PCB components back

Active project

This is an active project under development as spare time allows, it is a hobby after all. More information will be made available as results are achieved.

Results so far:

  • Operating voltage: 1.8v to 3.8v (lowest 1.8v = AVR MCU running at 1 MHZ, highest 3.8v = Radio, anything above may damage it)
  • 12/03/2022: Waiting for ordered components to arrive.
  • 1/04/2022: The SMD RGB LEDs, Hall effect sensors and SMD resistors have arrived. Still waiting on more parts. The pandemic and global resource shortages, not to forget the impact of the Russian attack on Ukraine, has big impact on supply chains. This is very noticeable at present.

SMD resistors

Surfave Mount Device - Resistors

1206 Surface mount device resistors kit have arrived.


Surface Mount Device - (Red Green Blue) Light Emitting Diode

Low power 0603 SMD RGB LEDs to indicate the state of the active transmitter/transceiver.


Surface Mount Device - Magnetic field sensor

The micro magnetic field sensors, these are used to switch the transmitter on and off using a magnet.

Buck/Boost PSU

Buck and Boost Power supply unit

Not part of the transmitter, but for research into power management and measuring for the transmitter.

Mini GPS receiver

Mini GPS receiver

(old type) Mini GPS receiver with patch antenna

RF Module

RF Module

Micro radio transceiver module.

Transceiver Module

RF transceiver module

Various RF transceiver modules were used for testing purposes.


Pre production checks

Confirming pinout, footprint component specs

  • 20/04/2022: MCUs (5) for the smart falconry telemetry unit have arrived. Very poorly packaged, but appear to be intact
  • 21/04/2022: SMD capacitors (0603,0805 and 1206) have arrived, still waiting on some active components to arrive.


Smart falconry telemetry microcontroller

Smart falconry telemetry micro controller.

0603 SMD capacitors

0603 SMD capacitors

0603 SMD capacitors.

0805 SMD capacitors

0805 SMD capacitors

SMD capacitors.

1206 SMD capacitors

1206 SMD capacitors

Larger SMD capacitors.

RF transmitters, rules and regulations (as proclaimed in 2022 : Agenschap Telecom NL the local authority at present)
  • Transmissions in the 144 MHz (2 meter band) by unlicensed parties for this frequency range and limited by:
    • Maximum power of 100 mW (supplied to fixed antenna).
    • Fixed antenna ([not removable],don't want antennas with any gain being attached)
  • If complaints are received from Amateur radio operators (interference) then it must be shut down and stopped.

Got that out the way. Considering there is always a licensed Amateur Radio Operator (PD9JS) around, another 'rule (law)' states that anyone can operate amateur radio equipment (on any legal (for that operator) frequency, power level and modulation mode) if under the supervision of a licensed radio amateur operator. Thus activating APRS and using it to track my feathered friends with the help of the local APRS HAM community should not be a problem. A radio amateur license is not that hard to get.and you need it if you're going down the APRS route on 144.800 MHz (Europe). Search for a local HAM radio group near you and get connected and involved.

Considerations for success

This is the first serious real world full stack project (by full stack is meant: hardware, firmware and software) being done after 30 years of inactively as an electronic engineer and technician. Much has changed since then, and knowing the devil is in the details, the footprints of the printed circuit board as well as the pinouts of the components need to confirmed prior the manufacturing the PCBs.

The printed circuit boards are the most expensive investment of this 'no budget' project and will be even more expensive is a redesign of an already made PCBs is required. For this reason all 'Bill Of Materials' components need to be physically available to enable checking that the footprints on the PCB ares correct and that the electrical connections are conform to the component designated pinouts. Hence the wait for all electrical and electronic components to be available physical (size) and electrical (pinout functionality) confirmation.

PCB design accepted for production

PCB design accepted for production

  • 02/06/2022: As expected, the components for the simple falconry transmitter have nearly all arrived and been tested so far. So it's time the get the PCB design approved for production and get it manufactured.
  • 04/06/2022: The falconry transmitter PCB design was accepted, approved and is now in production for a batch of 20 PCBs.

Progress on manufacturing

  • 21/06/2022: As promised the PCBs manufactured by JLCPCB have been delivered (vacuum sealed with a dehumidifier) on time and at a very reasonable price (for a no budget project), thus a definite recommendation for PCB manufacturing and an address I am sure to use again in future!
  • 21/06/2022: Important note to self: Still waiting for components from 'Aliexpress' who for the last two months have been claiming things have been delivered while they are not and marked orders as completed! Thus next time factor in that suppliers can go bad and prepare to order components locally at a higher price, is a better deal than paying money for nothing never delivered and you have no recourse. Lesson learned! Any sponsors? Moving on.

Currently busy with another project that should take another two weeks and then the art of soldering the available components on the first test boards begins...

Manufactured PCB back

Falconry telemetry real PCB back

An image of the bare manufactured PCB, with castellated edges.

Manufactured PCB front

Falconry telemetry real PCB front (component side)

This is where the SMD electronic components that do the work are soldered onto.

Actual size

Size of PCB compared to 50 Euro cents coin

Not the perfect measure, but I'm an average guy with an average thumb.

SMD soldering tip

SMD soldering tip

The Soldering iron tip I use for SMD work.

Progress.. Zero at present
  • 23/07/2022: Trying to make ends meet! There is no time available at present. In a society where I must pay commercial businesses to be able to pay my government tax, fast rising uncontrolled inflation, I must pay my bank (they finally have us all) to be able to put my cash in "the system" interest rate NEGATIVE! and do any transactions. Fuel prices through the ceiling, a government that does nothing and everything according to media is caused by the war that Russia started. Leaves me with little time for projects.
  • 23/07/2022: Even Aliexpress has gone bad claiming things delivered while nothing received (5 times in a row) = other source required. Moral to the story: Need time to ensure continuation on other levels... I will be back (soon)

SMD soldering started

SMD soldering started

  • 05/08/2022: Final have a few hours on this Friday to work on the telemetry project. Started soldering the SMD components onto the PCB. This is not an easy task doing by hand with a soldering iron.
  • 06/08/2022: This batch will be run of five prototype boards. And another smart idea has arrived to implement this version. Still have to see if the firmware can support it. Looks like the simple telemetry project is going to be smart after all.
  • 06/08/2022: Have still not received the voltage regulators and will need to source them elsewhere. However the telemetry unit can run of 3v lithium cell without one.
LP2981AIM5x-3 0

LP2981AIM5x-30 voltage regulators

  • 24/08/2022: The LP2981AIM5x-30 3.3V regulators have finally arrived. Now I have power source diversification available.
  • 24/08/2022: Also 4 433MHz transceiver modules have arrived. The one used for the proof of concept is destined to become a proximity beacon transmitter for these telemetry units, but more about this later.
  • Challenge that remains is to find the time to move ahead with construction. In the mean time, a 'jig' needs to be made to program the MCUs inline as well..

Telemetry components

Building the in-circuit programming interface

In-circuit programming interface build

  • 05/09/2022: More components have arrived. The 1.27 mm headers required to construct the in-line programmer for the basic telemetry transceiver. The PCBs are already soldered and waiting to be programmed. A 'test' GSP module has also arrived for the advanced telemetry transceiver as well. Next step = Engineer and in-circuit programmer with level shifters from 5V (Arduino for programming boot loader) to 3.3V for target telemetry unit.
  • Note to self: Clean the flux off the soldered PCBs once done soldering.
Providing resources for interested parties to investigate use and improve.

ATTINY telemetry schematic

  • The circuit diagram and schematic have been done using KICAD 6. The compressed project folder is available for download here.
  • PCB design is the tricky part as you want the castellated printed circuit board edges to coincide with the third party RF module design.
  • Having matched the controller PCB with the RF module, care should be taken that the external shielding of the RF module should be facing away of the controller PCB. As this makes it very difficult to join the two PCBs and also is a hazard for short circuits during the expected lifetime life time of the transponder.
  • The code is C++ and written using the Arduino IDE 1.8.16 and can be downloaded from here.
  • It makes use of interrupts and sleep (power down mode) to conserve energy between transmission cycles, currently set to two second periods.
  • A crucial part is setting up the radio. Although it is a fully fledged low power transceiver, managing it rather complex and requires processing power and resources the ATTiny85 does not have. Silicon Labs, the designers of the sl4463 module made it possible to 'download' a fixed setting configuration to the transceiver at startup.
  • My default radio module configuration is included in the code in the folder "\src\si4463\radio" and will put transmissions in the 433 MHz ISM band. The RF module that uses the sl4463 I used is the RF4463PRO from G-NiceRF.
Source code for the ATTiny85.

ATTINY85 telemetry source code

Configuring the transceiver module.
  • With a more powerful MCU the transceiver can be managed and configured real time and makes for some very interesting possibilities, however the ATTiny will have to make do with a predetermined configuration with preset default values.
  • Silicon Labs has developed a utility program to be able to create the radio configuration files to suite your needs. You may want to change the transmit frequency, modulation sort or power output and more..
  • The application is called the Wireless Development Suite (WDS). It has a steep learning curve, but once understood makes it possible to create radio configurations you can just upload to the RF module and it will function as instructed. It is getting very difficult to find this application on-line. For this reason I have made it available here.

To be continued ...