European scientists bounce first LoRa message off the Moon
Image credit: Dreamstime
'Internet of Things' standard LoRa could become relevant for future lunar communications.
A European team of scientists have, for the first time ever, bounced a LoRa (LOng RAnge) message off the Moon. The feat set a new record of 730,360km for the furthest distance a LoRa message has ever travelled. It was also the first time a data message was bounced using an off-the-shelf small RF (radio-frequency) chip. For a brief moment in time, the entire message 'PI9CAM' (the call sign of the telescope; actual message pictured below) was in space on its way from Earth to the Moon and back.
The experiment also proved that LoRa technology, used for many IoT (Internet of Things) applications, can cover such great distances and that it is possible to send and receive low-powered messages from the Moon. This could become relevant for future lunar communications.
The team, some of whom were licensed radio amateurs, consisted of Jan van Muijlwijk (CAMRAS); Tammo Jan Dijkema (CAMRAS); Thomas Telkamp (Lacuna Space), and Frank Zeppenfeldt (ESA). To achieve the transmission, the team used the Dwingeloo radio telescope, operated by the CAMRAS foundation in the Netherlands. The radio telescope has a history of being used in amateur radio experiments and is now often used for Moon bounces.
Nicolas Sornin, co-inventor of LoRa, said: “This is a fantastic experiment. I had never dreamed that one day a LoRa message would travel all the way to the Moon and back. I am impressed by the quality of the data captured. This dataset is going to become a classic for radio communications and signal processing students. A big thumbs up to the team and CAMRAS foundation for making this possible.”
Telkamp, CTO of Lacuna Space, a global connectivity provider for the IoT, said: “Seeing the message coming back from the Moon was exhilarating. From the round-trip time we were able to calculate the distance to the Moon, matching very well the predicted values of Nasa's JPL Horizons ephemeris system. We even used the echo to see the shape of the Moon, which we didn’t imagine we could.”
LoRa is one of the low-power wide-area network communication technologies and is Semtech’s proprietary ultra-long-distance wireless transmission technology. On 5 October 2021, the team transmitted the signal with a Semtech LR1110 RF transceiver chip (in the 430-440Mhz amateur band), amplified to 350 Watt, using the 25-metre dish of the telescope. 2.44 seconds later, it was received by the same chip.
Using the LR1110 RF chip, the team also measured the frequency offset due to the Doppler effect caused by the relative motion of the Earth and the Moon.
One of the messages sent and received contained a full LoRaWAN frame, consisting of a header (information such as device address and message counter), payload (the data actually sent), and payload CRC (integrity check of payload).
In addition to the LoRa chips, the team used an SDR (software-defined radio) to capture both the transmitted and received signal for further analysis. These measurements together with analysis notebooks will be published as open data. An in-depth overview of the entire experiment and results will be presented at The Things Conference in January 2022.
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