Quick answer: On a 905 nm rangefinder module datasheet six fields decide whether the part fits: minimum range, the accuracy formula per distance band, update rate, interface and logic level, size and weight, and the reflectivity condition on the maximum range. Our four 1,200 m modules all publish at $130 USD per unit, yet minimum range spans 0.1-5 m and update rate 1-3 Hz to 2-20 Hz.
Four modules, one headline number, four different parts
The LR1200E2 ranging module, the LRF1200A1 compact module, the SPD1200N0 cylindrical module and the SPD1200S2G with integrated gyroscope all say 905 nm, 1,200 m and UART-TTL, and all four currently show a published price of $130 USD per unit. Sourcing on the headline would make them interchangeable. They are not, and the datasheet is where the differences live.
| Datasheet field | LR1200E2 | LRF1200A1 | SPD1200N0 | SPD1200S2G |
|---|---|---|---|---|
| Ranging range | 4-1,200 m | ≥5-1,200 m | 0.2-1,200 m | 0.1-1,200 m (max 1,400 m) |
| Accuracy, close in | ±1 m (6 ≤ d < 500 m) | ±1 m (5-100 m) | ±0.3 m (≤100 m) | ±0.2 m (≤400 m) |
| Accuracy, long end | ±50 cm + d·1‰ (500-1,000 m) | ±(1 + L×0.4%) m (>100 m) | ±0.3 m + d·0.7‰ (100-1,200 m) | ±d·0.75% (400-1,200 m) |
| Accuracy at 1,000 m (from the stated formula) | ±1.5 m | ±5 m | ±1.0 m | ±7.5 m |
| Measurement frequency | 2-10 Hz adaptive | 1-3 Hz | 2-15 Hz / 4-15 Hz adaptive | 2-20 Hz adaptive |
| Supply voltage | 3.3-5 V | 3.3 V ± 0.1 V | 3.3-5 V | 3.3-5 V |
| Operating power | ≈0.4 W short range; max ≈1 W | Not stated | ≈0.45 W avg; ≤0.75 W max | ≈0.65 W avg |
| Dimensions | 25.65 × 13.2 × 24.6 mm | Ø23 × 40 mm | Ø15.7 × 21.3 mm | 24.6 × 11.4 × 26.3 mm |
| Weight | ≤10 g | 18 g | ≈5 g | ≈10 g |
| Beam divergence | <4 mrad | Not stated | <4.5 mrad | <6 mrad |
| Protection rating | IP67 (lens cavity) | On request | IP67 (lens cavity) | IP67 (lens cavity) |
| Operating temperature | -20 to +55 °C (-40 °C custom) | On request | -20 to +60 °C | -20 to +60 °C |
| Published price | $130 USD / unit | $130 USD / unit | $130 USD / unit | $130 USD / unit |
Published prices are the figures currently shown on the model pages; confirm current terms in writing.
Field 1: minimum range, the field nobody reads until the bench test
Across these four parts the minimum range varies by a factor of 50: 0.1 m on the SPD1200S2G against 5 m on the LRF1200A1. If your fixture puts a wall or a calibration plate two metres in front of the lens, two of these modules report nothing during bring-up and look broken.
This is also where a datasheet band gap bites. The LR1200E2 is specified 4-1,200 m, but its accuracy formula starts at 6 m and stops at 1,000 m. Between 4 and 6 m, and between 1,000 and 1,200 m, the module still returns readings with no published accuracy figure. If your loop depends on either window, ask for the number rather than interpolating one.
Field 2: accuracy is a piecewise function, not a single number
Notice the two accuracy rows. Ranked close in, the SPD1200S2G wins at ±0.2 m to 400 m. Ranked at 1,000 m it is the worst of the four at ±7.5 m, because its long-range term is a straight percentage of distance (0.75%) with no fixed floor. The SPD1200N0, four times less accurate close in, is seven times better at 1,000 m on its 0.7‰ slope.
So “which module is more accurate” has no answer until you name a distance. Work the formula at your working distance before comparing parts – ours or anyone’s. More on fixed-metre versus percentage terms in understanding rangefinder accuracy specs.
Field 3: update rate, and what “adaptive” means
These four run 1-3 Hz, 2-10 Hz, 2-15 Hz and 2-20 Hz. Those bands are not marketing: adaptive means the module takes longer per reading when the echo is weak, so the low end is what you get on a dark surface at distance. Size your loop for the low end.
The LRF1200A1 at 1-3 Hz is a handheld-style cadence – fine for a spot measurement, wrong for anything tracking a moving platform. For that end of the spectrum see our note on choosing an update rate for moving platforms.
Field 4: interface, and the logic level most datasheets omit
All four list UART-TTL, three of them at 115200 bps default. That tells you the protocol, not the electrical level. Our LR1200E2 and SPD1200N0 manuals state the module supply range (3.3-5 V) but do not state the TX/RX logic-level voltage, so we publish that as an open field rather than inferring 3.3 V from the supply rail. The LRF1200A1 does state TTL 3.3 V on its serial pins.
Two more facts to extract before you write a driver. This family returns distance as the real value multiplied by 10 inside an 8-byte frame behind a 55 AA header, and the transmit and reply checksums cover different byte spans – the most common integration error we see (details in serial protocol: frames and checksums). Unit conventions also differ by family: our short-range parts report millimetres – see what actually works over I²C.
Field 5: mechanical form and supply rail
Same headline range, four different mechanical problems. The SPD1200N0 is a Ø15.7 × 21.3 mm cylinder at about 5 g with a sealing groove, which drops into a tube mount. The LRF1200A1 is a Ø23 × 40 mm barrel at 18 g. The other two are rectangular, about 10 g. On a weight-budgeted payload, 5 g versus 18 g on one sensor is a real line item.
The supply row matters just as much: the LRF1200A1 wants 3.3 V ± 0.1 V – a regulated rail, not a 5 V bus. The other three accept 3.3-5 V. Also check inrush: the LR1200E2 and SPD1200S2G both draw about 350 mA with a ≤200 ms start-up, which a marginal LDO will brown out.
Field 6: read what is marked “on request”
The most useful column on a spec sheet is often the one with gaps. The LRF1200A1 publishes 11 spec rows against 24-32 for the other three, with protection rating and operating temperature both on request – a fair description of a module not characterised for outdoor sealing, not a claim that it fails. Average laser power and response time are on request across the other three. The SPD1200S2G protocol document is still under technical review on our side, so a design that needs a frozen frame format today should start from one of the other models.
A vendor that fills those cells with plausible numbers is guessing on your behalf. Ask which rows are measured, which are typical and which are estimates, then hold the answer in writing. All four are 905 nm IEC Class 1 per IEC 60825-1 and all four quote MTBF ≥1500 h, a ≥98% valid measurement rate and ≤1% false alarm rate. For the host side of a UAV integration, the ArduPilot rangefinder documentation covers serial port setup.
Frequently asked questions
What should I check first on a laser rangefinder module datasheet?
Minimum range and the accuracy formula at your working distance. Both are routinely ignored in favour of the maximum range headline, and both decide whether the part works in your fixture.
Why do two modules with the same maximum range quote such different accuracy?
Because the long-range term is built differently. A fixed offset plus a per-mille slope (±0.3 m + d·0.7‰) behaves unlike a flat percentage (d·0.75%). At 1,000 m that is ±1.0 m versus ±7.5 m.
Is the maximum range figure measured on a dark or a bright surface?
Long-range figures in this class are stated against high-reflectivity conditions, with a separate low-reflectivity figure where the source table gives one. Always ask which condition a range number belongs to before you compare two vendors.
The datasheet does not give a UART logic level. Can I assume 3.3 V?
No. Ask. The module supply range and the signal logic level are separate specifications, and a 5 V-tolerant supply pin implies nothing about the TX/RX pins. We flag this as an open field on the models where our own manuals do not state it.
Send us your working distance, surface type, update rate and supply rail, and we will tell you which part these fields rule in – talk to our engineering team.