b'Environmental geophysics Environmental geophysicsWelcome readers to this issues column onyourself. Interestingly (at least to me), geophysics applied to the environment.Dave contacted me after my article in For this issue, I welcome Dave Allenthe June 2023 issue Preview where I had from Groundwater Imaging (https:// skimmed this subject; he kindly o\x1eered groundwaterimaging.com.au/) asto write some more about modern the guest contributor. He is going tocommunications and GNSS. Thanks Dave!introduce many of us to a more modern world of geophysical instrumentationBefore we go any further, I need to correct and, possibly more importantly, dataan error that I made in the last column. transfer. There is a fair bit of jargon hereIn that column I incorrectly stated that (and more than a few abbreviations)weBradley Moggridge worked with the have tried to explain most terms, butCSIRO. In fact, Bradley is an Associate some you may just have to look up forProfessor at the University of Canberra.Mike Hatch Associate Editorfor Environmental geophysics michael.hatch@adelaide.edu.auCommunicating using microwaves -3.Geophysical sensors transmittingDistributed geophysical devices may a primer for geophysicists autonomously from mining anduse either a Low-Power Wide Area agricultural equipment, Network (LPWAN), long range WiFi, 4.Precision positioning and timing usingcellular or satellite communication. The GNSS (Global Navigation Satellitemost promising LPWAN technology for Systems) correction services, and geophysics is likely to be Long Range 5.Ergonomic design improvement ofWide Area Networks (LoRaWAN) which geophysical controllers without therequire at least one Gateway device, need for long cables and connectorstypically connecting to the internet between sensors and controllersi.e.,(but not a requirement). The Gateway a better environmental footprint. is typically a computer or router that sits between di\x1eerent networks or Interestingly, the same communicationapplications converting information, frequency range is used for bothdata or other communications from cellular communications and GNSSone protocol or format to another, communication, so the learning curvethen connects to node devices that Dave Allenfor both cellular and GNSS technology isare connected to our geophysical Ground Water Imaging Pty Ltd similar, and there is a lot in common, assensors. There is a cost playo\x1e between David@GroundwaterImaging.com well, between emerging low earth orbitLoRaWAN and direct connection to communication systems and GNSS. public cellular networks or satellites Microwave communication facilitatesas the gateway infrastructure is more Microwave communication technologytransfer of large data volumes quicklyexpensive than a combination of several is now ubiquitous throughout thewith compact, low-power, low-costdirect cellular network connections. modern world. However, many of uscircuitry, and small antennae. In someLoRaWAN nodes are extra-low-power (younger than Mike) were trained inapplications the signal transmissiondevices and communicate only small the days when microwave frequencydistance can be thousands of kilometrespackets of information via LoRa communication was limited mainly(e.g., satellite to earth station), but attechnology (packets of information sent to telco use and ground penetratingthe high frequencies used in someover chirp pulses) distances typically radar (GPR) and was certainly not partsystems signal attenuation can limitover 10 km in the bush, or just 3km of our legacy geophysical instrumentstransmission distances. Examples of shortin noisy urban centres. The small (maybe these should be consigned todistance communication are BlueToothdata packet size combined with the the boat anchors category). There isand WiFi, with distances typically stillrelatively small distance limit are both a lot to learn to take full advantage ofin the 10 to 100 m range when usedfactors that reduce the usefulness of the opportunities these technologiesin newer geophysical controllers. 5GLoRa technology for many geophysical provide to geophysics and the moderncellular technology uses frequenciesapplications and geophysical instruments that need to send e.g., geophysicist. high enough that towers must be closelyunprocessed, full waveform data.spaced (on the order of 200 m apart). Typical opportunities in geophysicsFor this reason, we dont see muchData sent using LoRaWAN technology include: advantage using 5G cellular servicesuses basic (but modi\x1ded) internet in the bush. Rather, 4G will continue toprotocol as the basis for communication. 1.Distributed acquisition systems withbe important, with frequencies in theBut, as these systems are limited both multiple nodes / cable replacement, 700 MHz band, rather than the 2.4 GHzby low-power transmission and low 2.Telemetered time-lapse geophysics, and 5 GHz bands commonly used in 5G. frequency, messages typically have to DECEMBER 2023 PREVIEW 36'