How it works, and the numbers.
What it measures, how it works, what comes out of the box, what it needs in the field, and the full specification.
What it measures
Temperature (DTS). Raman backscatter, anti-Stokes to Stokes ratio, on single-mode or multimode fibre. Home range 0.5 to 5 km on single-mode; multimode to about 10 km at coarser resolution. Spatial resolution in the 0.5 m class, sampled every 0.41 m. Noise 0.11 K at 2 km in five minutes. Single-ended, double-ended loop or mirror-ended layouts through an optical switch. Two Peltier-held reference coils inside the box and double-ended reading through the loop make the calibration automatic on your own cable.
Acoustics (DAS). Coherent-phase Rayleigh backscatter on single-mode fibre: quantitative strain, not only event detection. 40 to 50 km single-ended. Gauge length 1 to 40 m in software, channels from 0.41 m native with programmable stacking, pulse rates to 20 kHz. GNSS pulse-per-second and a 10 MHz reference input for arrays of several units.
Not this instrument. Brillouin strain. Fibre Bragg gratings. Fibres carrying live telecom traffic, where the pump pulse is too strong for a shared fibre. Fire-detection certification. Acoustic raw data comes as decimated streams and raw snapshots as standard; continuous raw streaming is an option.
How it works
- 1
A pulse of light goes in
The instrument sends short pulses of laser light into your fibre. Any single-mode or multimode cable with a common APC connector will do.
- 2
Every point along the fibre answers
A tiny fraction of the light scatters back from every point along the glass. The arrival time says where it came from. The colour balance of the returning light gives the temperature at that point.
- 3
You get a profile, every half metre
Many pulses are averaged into one temperature profile along the whole cable. With the acoustic tile, the phase of the returning light is read as well, which turns the same fibre into thousands of strain sensors.
Calibration is automatic on your own cable. Two temperature-controlled reference coils inside the instrument give the absolute scale, and reading a looped cable from both ends removes the cable’s own loss. The method agrees with the open-source dtscalibration reference to 0.014 K on the same raw data, and the files it writes load into that toolchain without conversion.
Temperature
- A short pulse of light goes into the fibre.
- Every point along the glass sends back a faint glow, in two colours.
- The balance of the two colours is the temperature at that point.
- The time the glow takes to come back says where it came from.
Acoustics
- The same kind of pulse goes in, thousands of times a second.
- The light that comes back carries a phase, like the hand of a clock, for every half metre.
- When the ground moves, the glass stretches by a few parts per billion and the hand turns.
- Every half metre becomes a vibration sensor; plotted over time, events draw themselves.
Resolution and noise
Resolution and noise trade against each other, and against averaging time. The modes are a software setting, so you can switch between them from one profile to the next, or run a fine profile once an hour and a low-noise one in between. Averaging longer lowers the noise further: four times the averaging halves it.
Multimode fibre reaches about 10 km at coarser resolution. On single-mode fibre the home range is 0.5 to 5 km. Every rental starts with an acceptance measurement on your own cable, so the numbers you plan with are the numbers you get.
| Mode | Resolution | Noise at 2 km | Use it for |
|---|---|---|---|
| Fine | 0.43 m | 0.154 K | thin layers, short hot spots, borehole interfaces |
| Standard | 0.48 m | 0.109 K | most campaigns |
| Low noise | 0.61 m | 0.077 K | small temperature differences over long reaches |
Table 1. Temperature modes on 2 km of single-mode fibre, 300 s averaging. Resolution is the 10 to 90 % response to a step; noise is the standard deviation at the far end.
Three configurations, one platform
| DTS | DAS | DTS + DAS | |
|---|---|---|---|
| Measures | Distributed temperature | Quantitative acoustic strain | Both, time-shared on one fibre |
| Fibre | Single-mode and multimode | Single-mode | Single-mode and multimode for temperature; single-mode for acoustics |
| Fibres per instrument | 2 standard; 4 or 8 with the switch option | 1 | 4 standard |
| Typical use | Hydrology, glaciology, geothermal | Dark-fibre seismology, research arrays | Wells, pipelines, combined studies |
The acoustic capability is one insert tile. A temperature unit becomes a combined unit on site by adding the tile; nothing goes back. Enclosure, software and data formats are the same in every configuration.
What comes out: dashboard, API, files
dimensions: x (bins, 0.41 m) time (profiles)
variables:
st, ast Stokes, anti-Stokes counts (x, time)
rst, rast reverse-direction channels counts (x, time) double-ended only
tmp calibrated temperature degC (x, time)
tmp_var per-bin variance K^2 (x, time)
ref_coil_1, _2 Peltier-held reference coils degC (time)
ext_pt100_1..4 external RTD channels degC (time)
acq_time averaging time per profile s (time)
attributes: instrument serial, firmware version, acquisition settings,
fibre preset, switch channel, calibration method, GNSS fix
Listing 1. Variables in the netCDF file written per measurement. The layout follows the dtscalibration convention, so the file loads without conversion.
| netCDF | dtscalibration-compatible; one file per channel per period |
| CSV | distance, temperature, variance per profile |
| HDF5 | temperature and acoustic containers with the same metadata |
| miniSEED, SEG-Y | acoustic channels for seismology toolchains |
| PRODML, WITSML-shaped | well-monitoring systems |
| Modbus TCP, MQTT, REST | live values and alarms to plant systems |
Every rental includes a web dashboard with live profiles, time series, alarms and the campaign report, and an API. REST for profiles, events and status, MQTT for live values, Modbus TCP for control rooms. The same data is written as files in the formats listed.
The instrument runs in one of four modes: pushing to a cloud account, serving on the site network, writing to a local disk only, or air-gapped with configuration by USB stick. The measurement chain is identical in all four; the cloud is a sink, never a dependency. When a link drops the unit keeps its schedule and catches up afterwards.
Power in the field
| Mode | Average draw | On 100 Ah | Notes |
|---|---|---|---|
| Temperature, one 5-min profile per hour | 2.3 W | about 20 days | a 150 W panel carries it February to October at Danish latitude |
| Temperature, one profile per 4 h | 0.8 W | about 2 months | glacier and permafrost schedules |
| Temperature, continuous | 21 W | about 2 days | use PoE or mains |
| Acoustics, continuous | 25 W | under 2 days | cannot duty-cycle; mains, fuel cell or a large solar kit |
Table 2. Average draw and endurance on a 12 V, 100 Ah lithium iron phosphate battery (about 1.1 kWh usable).
Inputs are 9 to 36 V DC and 802.3bt power over Ethernet. Between profiles the instrument sleeps and only the scheduler and the reference coils stay powered. If the supply fails, the files are closed cleanly and the schedule resumes when power returns.
Specifications
| Temperature mode | |
|---|---|
| Range | 0.5 to 5 km single-mode; multimode to about 10 km at reduced resolution |
| Spatial resolution | 0.5 m class; 0.48 m 10-90 % on 2 km single-mode |
| Noise | 0.11 K at 2 km, 300 s averaging |
| Sampling | 0.41 m |
| Acceptance benchmark | 0.20 K at 0.6 m, 2 km single-mode, 300 s; or 0.20 K at 1.0 m, 600 m multimode, 60 s |
| Update | seconds (coarse) to minutes (precise) |
| Fibre | single-mode G.652 and G.657; multimode 50/125 and 62.5/125 |
| Layouts | single-ended, double-ended loop, mirror-ended; switch 1x2, 1x4, 1x8 |
| Acoustic mode | |
|---|---|
| Method | coherent phase, quantitative strain |
| Range | 40 to 50 km single-ended |
| Gauge length | 1 to 40 m, software selectable |
| Channel spacing | 0.41 m native; programmable stacking |
| Pulse rate | to 20 kHz, range dependent |
| Synchronisation | GNSS PPS in and out, 10 MHz reference in |
| Optics | |
|---|---|
| Wavelength | 1550 nm |
| Laser safety | Class 3B; hardware interlock; automatic power reduction on fibre break |
| Connectors | swappable bulkhead adapters FC/APC, SC/APC, E2000/APC, LC/APC |
| Power and environment | |
|---|---|
| Inputs | 9 to 36 V DC; 802.3bt PoE |
| Draw | 2.3 W averaged at one profile per hour; 21 W continuous temperature; 25 W continuous acoustics |
| Enclosure | IP67 field case, fanless; 19-inch rack variant on request |
| Ambient | -20 to +50 C |
| Data and interfaces | |
|---|---|
| Network | 1 GbE; LTE modem option; Wi-Fi for commissioning |
| Files | netCDF (dtscalibration), CSV, HDF5, miniSEED, SEG-Y, PRODML and WITSML-shaped |
| Live | Modbus TCP, MQTT, REST |
| Modes | cloud, LAN, disk-only, air-gapped; store-and-forward |
| Field I/O | 2x RS-485, SDI-12, 4x 4-20 mA, 4 external and 2 internal PT100, 4 pulse inputs, 4 relays |
| Raw access | decimated streams and raw snapshots standard; continuous raw streaming optional |
Outside these numbers? Ask.
Longer fibre, finer resolution, a faster update, an unusual connector, a sensor or a data path we have not listed, a site with no power at all. Much of what looks out of spec is a configuration, a tile or a cable away, and we build to order where it is not. Tell us the question and the site. If we cannot do it, we will say so and point you to who can.
Questions
- Can I use my existing cable?
- Usually. Single-mode G.652 and G.657, multimode 50/125 and 62.5/125, any of the common APC connectors. Tell us the fibre type, length, connectors and how the ends are reached; for acoustics the cable's coupling to the ground matters more than the fibre. No cable on site? We supply armoured, borehole and hybrid single-mode plus multimode sensing cable, terminated and cut to length, with the instrument.
- How is it calibrated?
- Two Peltier-held reference coils inside the instrument give the absolute scale; reading the loop from both ends removes the cable's differential loss; external PT100 inputs let you add calibration sections of your own. No baths in the field.
- What if it does not perform on my fibre?
- Every rental starts with an acceptance benchmark run on your own cable: 0.20 K at 0.6 m over 2 km of single-mode fibre with five-minute averaging, or 0.20 K at 1.0 m over 600 m of multimode with one-minute averaging. You see the result before the campaign starts, and every figure we report carries the fibre, the length and the averaging time it was taken with.
- Does it run on battery?
- Yes, for temperature. At one profile an hour it draws about 2.3 W and lasts about 20 days on a 100 Ah battery; a 150 W panel keeps it going most of the year at Danish latitude. Continuous acoustics needs mains, PoE or a fuel cell.
- Can I get raw data?
- Decimated acoustic streams and raw snapshots as standard. Continuous raw streaming is an option; tell us the data rate your processing needs.
- Can I buy one outright?
- No. Scatterways is rented by the month: the instrument, the cable if you need one, installation help, remote operation and processing, in one monthly line. Campaigns from two weeks, seasons month by month, continuous monitoring on a service contract.
- Do you install on site?
- If you want us to, yes. The default is simpler: the box ships, your technician or student connects it on a video call with us, and we operate it remotely. Air-gapped sites get a local operating plan instead.
- Can several units run as one array?
- Yes. Each unit takes GNSS pulse-per-second and a 10 MHz reference, so units on separate fibres share one clock and their acoustic channels line up to the sample.
- Is it safe?
- The laser is Class 3B behind a hardware interlock. Power drops automatically if the fibre breaks or a connector is opened, and the instrument reports it.
Put your fibre to work.
Tell us about your fibre and your question. You get a call, a plan for your site and a monthly price.