Wired Beartooth article

https://www.wired.com/2016/02/beartooth/

OUR SMARTPHONES CAN already do so much, but one area where they fail is off-grid communications. Journey beyond the reach of a compatible cellular data network or a capable Wi-Fi signal, and your access to the vast telecoms infrastructure disappears.

Going off the grid doesn't even require a trip into the boonies. You can find yourself without access in areas where you have either Wi-Fi or cell coverage, but your connection falters because there are too many users congesting the network—a common occurrence at concert venues and big conferences.

A new product from the Bozeman, Montana-based company Beartooth provides direct off-grid communications between smartphone devices. The pocket-sized transceiver pairs with your smartphone via Bluetooth and allows you to talk to your other Beartooth-carrying friends without having to rely on external infrastructure like Wi-Fi networks and cell towers. The simplest explanation: it turns your smartphone into a texting and push-to-talk (PTT) style voice walkie-talkie. But unlike a walkie-talkie, you get to keep the computing power, touchscreen, and user interface of the smartphone. So while you may be cut off from the Internet in the woods, you'll at least be able to communicate with your friends in familiar ways.

Introducing LoRa

http://www.instructables.com/id/Introducing-LoRa-/

LoRa™ =Long Range wireless data telemetry and relates to a radical VHF/UHF 2-way wireless spread spectrum data modulation approach that has recently been developed & trademarked (™) by Semtech - a long established (1960) US multinational electronics firm. Refer [1]=> http://www.semtech.com/

The technology behind LoRa™ was developed by Cycleo, a French company acquired by Semtech in 2012. LoRa™ is proprietary, but it appears to use some sort of "simpler" CSS (Chirp Spread Spectrum) pulsed FM "sweeping frequency" modulation rather than DSSS (Direct Sequence SS) or FHSS (Frequency Hopping SS).

Semtech's web site mentions that "LoRa™ technology offers a 20dB link budget advantage compared to existing solutions, which significantly extends the range of any application while delivering the lowest current consumption to maximize battery life."

Claimed ranges are typically x10 that of regular UHF wireless data systems. Yes -compared with regular narrow band data setups LoRa™ gives 100s of metres rather than 10s, several 1000m rather than mere 100s. Magic !

A Study of LoRa: Long Range & Low Power Networks for the Internet of Things

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5038744/

Abstract

LoRa is a long-range, low-power, low-bitrate, wireless telecommunications system, promoted as an infrastructure solution for the Internet of Things: end-devices use LoRa across a single wireless hop to communicate to gateway(s), connected to the Internet and which act as transparent bridges and relay messages between these end-devices and a central network server. This paper provides an overview of LoRa and an in-depth analysis of its functional components. The physical and data link layer performance is evaluated by field tests and simulations. Based on the analysis and evaluations, some possible solutions for performance enhancements are proposed.

Keywords: LoRa, Internet of Things, long range, low power

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1. Introduction

The essential difference between "the Internet" and "the Internet of Things" (IoT) [1] is that in the IoT, there is just "less of everything" available in a given device or network device: less memory, less processing power, less bandwidth, etc.; and of course, less available energy. This is either because "things" are battery driven and maximizing lifetime is a priority or because their number is expected to be massive (it is estimated that there will be 50 billion connected devices by 2020 [2]). This drive to "do more with less" leads to constraints that limit the applicability of traditional cellular networks, as well as of technologies, such as WiFi, due to energy and scalability requirements.

Another range of protocols and technologies has emerged to fulfill the communication requirements of the IoT: Low-Power Wide Area Networks (LPWAN). Colloquially speaking, an LPWAN is supposed to be to the IoT what WiFi was to consumer networking: offering radio coverage over a (very) large area by way of base stations and adapting transmission rates, transmission power, modulation, duty cycles, etc., such that end-devices incur a very low energy consumption due to their being connected.

LoRa (LoRa Alliance, https://lora-alliance.org) is one such LPWAN protocol and the subject of study for this paper. LoRa targets deployments where end-devices have limited energy (for example, battery-powered), where end-devices do not need to transmit more than a few bytes at a time [3] and where data traffic can be initiated either by the end-device (such as when the end-device is a sensor) or by an external entity wishing to communicate with the end-device (such as when the end-device is an actuator). The long-range and low-power nature of LoRa makes it an interesting candidate for smart sensing technology in civil infrastructures (such as health monitoring, smart metering, environment monitoring, etc.), as well as in industrial applications.

wiki and beartooth presents "the 33-centimeter band"

The 33-centimeter or 900 MHz band is a portion of the UHF radio spectrum internationally allocated to amateur radio on a secondary basis. It ranges from 902 to 928 MHz and is unique to ITU Region 2.^[1] It is primarily used for very local communications as opposed to bands lower in frequency. However, very high antennas with high gain have shown 33 centimeters can provide good long range communications almost equal to systems on lower frequencies such as the 70 centimeter band. The band is also used by industrial, scientific, and medical (ISM) equipment, as well as low powered unlicensed devices. Amateur stations must accept harmful interference caused by ISM users^[1] but may receive protection from unlicensed devices.

The 900 MHz frequency is also used as a reference band^[2] e.g. to express the total power or impact of the electric field "E" - expressed in V/m - or the power density "S" - expressed in W/m2 - of the overall cellular frequencies emission caused by all frequencies s.a. the four bands 850 / 900 / 1,800 / 1,900 MHz - which many GSM phones support and mobile phone operators use - used by all mobile phone operators at the same time to a certain space where e.g. humans are exposed to these frequencies over a certain span of time. More: Mobile phone radiation and health section.

In ITU Region 3, New Zealand domestically allocates 915 MHz to 928 MHz to amateurs.^[3] In Australia, this spectrum is allocated to radiolocation and scientific-medical services.

used by https://beartooth.com/pages/beartooth-tech-specs