Quick answer: SPD1200S2G is a 905 nm module with an integrated gyroscope: it reports attitude alongside distance and derives the span between two measured points. Range is 0.1–1,200 m (1,400 m max), single-point accuracy ±0.2 m to 400 m, tilt accuracy 0.3°, two-point radial error ±1 m to 500 m. Size 24.6×11.4×26.3 mm, about 10 g.
Most distance modules answer one question: how far away is that surface? A module with an onboard gyroscope answers a second: how far apart are those two surfaces? Take a reading on point A, then on point B, and the attitude solution between them gives the straight-line span — the height of a structure, the width of a gap, the clearance over a road — without walking to either point. For surveying and mapping, ground-based tower and powerline inspection, forestry and outdoor optics, that turns a distance sensor into a geometry sensor. Here is what SPD1200S2G publishes for that job — including the three separate error budgets people collapse into one.
The gyroscope specification, field by field
The integrated sensor is described in the source table as a high-precision gyroscope for attitude and spatial positioning. Its published figures are:
- Euler angle range: roll (X) ±180°, pitch (Y) ±90°, yaw (Z) ±180°
- Tilt accuracy (X, Y): 0.3°
- Heading accuracy (Z): ≤ 0.75° within 10 s
- Two-point radial distance error: ±1 m (≤500 m), ±1 m + d × 0.1% (500–1,200 m)
- Static two-point error: ≤±1 m (<100 m), ≤±3 m (100–500 m), ≤±5 m (500–1,000 m)
- Dynamic two-point error: ≤±1 m (<50 m), ≤±3 m (50–100 m), ≤±6 m (100–500 m), ≤±10 m (500–1,000 m)
Note the qualifier on heading accuracy: 0.75° is specified within a 10-second window. Yaw has no gravity vector to lean on, so the figure is bounded in time and behaviour beyond 10 s is not published. The rule that falls out: take the second reading promptly. Line up point A, discuss it for a minute, then line up point B, and the span sits outside the specified conditions.
Three error budgets, not one
The commonest misreading is to quote the ±0.2 m single-point ranging accuracy and assume the two-point span inherits it. It does not. The span is a computed quantity, and its published error is five times the ranging error at the same distance — ±1 m against ±0.2 m inside 400 m. That says where the uncertainty lives: not in the time-of-flight measurement but in the attitude solution relating the two readings. A more accurate ranging engine would not move this number; angular accuracy governs it.
The second thing to separate is static from dynamic. Both are published, and degrade at different rates:
| Tolerance you need on the span | Static two-point (tripod or braced) | Dynamic two-point (handheld or moving) |
|---|---|---|
| ±1 m | up to 100 m | up to 50 m |
| ±3 m | up to 500 m | up to 100 m |
| ±5 m | up to 1,000 m | not reached (±6 m from 100 m) |
| ±10 m | covered throughout | up to 1,000 m |
At a ±3 m tolerance, bracing the module against holding it is a factor of five in usable distance (500 m against 100 m). If your workflow is handheld, design to the dynamic column and add a mount if the numbers do not close. Both columns are the published error tables above, inverted.
One geometry note, computed from the published heading figure rather than taken from the manual: 0.75° of yaw uncertainty at 500 m is roughly 6.5 m of lateral arc. That does not contradict the ±1 m radial figure — the specification separates radial error, along the line of sight, from the angular term because they behave differently. A mostly radial span gets the radial figure; a span across the line of sight is governed by the angular term, so quote the static or dynamic budget.
How it compares with the rest of the SPD series
SPD1200S2G shares the 1,200 m class with three siblings that carry no inertial sensor. The trade is size, weight and power for the attitude data.
| Specification | SPD1200S2G with gyroscope | SPD1200N0 cylindrical module | SPD1200N2 square module | SPD1200D03 compact module |
|---|---|---|---|---|
| Ranging range | 0.1–1,200 m (max 1,400 m) | 0.2–1,200 m | 0.2–1,200 m | 0.2 m to ≥1,200 m |
| Ranging accuracy | ±0.2 m (≤400 m) · ±d × 0.75% above | ±0.3 m (≤100 m) · ±0.3 m + d × 0.7‰ | ±0.3 m (≤100 m) · ±0.3 m + d × 0.7‰ | ±0.3 m (≤100 m) · ±(0.4 + 0.006d) m |
| Ranging frequency | 2–20 Hz adaptive | 2–15 / 4–15 Hz adaptive | 2–15 / 4–15 Hz adaptive | 2–15 Hz adaptive |
| Integrated attitude sensor | Yes — gyroscope | No | No | No |
| Dimensions | 24.6 × 11.4 × 26.3 mm | Ø15.7 × 21.3 mm | Ø15.7 × 21.3 mm | 10.7 × 16.8 × 22 mm |
| Weight | ≈ 10 g | ≈ 5 g | ≈ 5 g | On request |
| Operating power | Avg ≈ 0.65 W | Avg ≈ 0.45 W · max ≤ 0.75 W | Avg ≈ 0.45 W · max ≤ 0.75 W | Not published |
| Beam divergence | < 6 mrad | < 4.5 mrad | < 4.5 mrad | Not published |
| Interface | UART-TTL, 115200 bps (9600 optional) | UART-TTL, 115200 bps | UART-TTL, 115200 bps | UART, TTL 3.3 V |
| Protocol document | Not yet released — under technical review | 55 AA, 8-byte frame | 55 AA, 8-byte frame | 55 AA, 8-byte frame, with a documented baud conflict |
Two honest observations. The gyroscope costs roughly double the weight (10 g against 5 g), about 0.2 W more average power and a wider beam (<6 mrad against <4.5 mrad) — but buys a lower minimum range, 0.1 m against 0.2 m, and a 20 Hz adaptive ceiling. And SPD1200S2G is, ironically, the model whose serial protocol we cannot yet publish: the upstream document is a holding card marked for technical review, so we hold it rather than reconstruct it from a sibling. SPD1200D03 has the opposite problem — a protocol document that contradicts itself on baud rate (115200 bps in the protocol section, 15200/9600 bps in the technical table), which we pass on as-is rather than choosing for you. Reading gaps like these is the subject of our note on what to check in a rangefinder datasheet, and fixed against proportional error terms is covered in accuracy specs: ±m against %.
Mechanical and environmental limits
The rest of the envelope is shared with the series: IP67 inside the lens cavity, IEC Class 1 under IEC 60825-1, −20 to +60 °C operating and −40 to +60 °C storage, shock at 1000 g/ms along the optical axis ten times per second, vibration at 5–50–5 Hz and 2.5 g, MTBF ≥ 1,500 h, startup ≤ 200 ms, inrush around 350 mA, receiving aperture 9.0 × 14.5 mm, accuracy rate ≥ 98% and false alarm rate ≤ 1%. Average laser power and response time are listed as on request. For attitude terminology, IEEE 1559 covers inertial sensor terms and definitions.
Frequently asked questions
How accurate is the two-point measurement?
Radial error between two points is ±1 m to 500 m, then ±1 m + d × 0.1% from 500 to 1,200 m. Static work: ≤±1 m below 100 m rising to ≤±5 m at 1,000 m. Handheld follows the dynamic band: ≤±1 m below 50 m rising to ≤±10 m at 1,000 m.
Why is the two-point figure worse than the ranging accuracy?
Because it is derived. Single-point ranging is ±0.2 m inside 400 m, but a span also carries the angular uncertainty of the attitude solution, which dominates. Improving distance precision alone would not tighten it.
Does the 0.75° heading accuracy hold indefinitely?
No. It is specified within a 10-second window and nothing beyond that is published. Take both readings in quick succession; treat a long pause as outside the specified conditions.
Can I get the serial protocol for SPD1200S2G?
Not from a published document today — the upstream protocol material is a holding card awaiting technical review, and we will not publish a frame format we cannot source. Its siblings SPD1200N0 and SPD1200N2 use a 55 AA 8-byte frame at 115200 bps, but we do not extrapolate that to the gyroscope model. Ask us and we will chase the document through engineering.
Designing span or height measurement into a surveying or inspection product? Tell us your distances and tolerance and we will say which column of the error table you land in — and where the specification is silent.