Long-Range Laser Rangefinder Module: 300-3000 m

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Quick answer: The three H-series modules compared here publish ranges at 90% and 10% reflectivity; the LRF3000A1 has a different stated test condition. The LRF300H 300 m module reaches 300 m at 90% and 100 m at 10%; the LRF600H 600 m module gives 600 m / 200 m; the LRF1500H 1500 m module gives 1,500 m / 300 m. The LRF3000A1 3,000 m module switches to a 12 g, 3.3-5 V, 1-10 Hz design.

Keep each range figure with its own reflectivity condition

For the three H-series modules, the 90% and 10% reflectivity ranges do not scale together. LRF300H to LRF600H doubles both columns; LRF600H to LRF1500H multiplies the bright-surface figure by 2.5 and the dark-surface figure by only 1.5.

Put concretely: the 1,500 m module measures 300 m against a 10% reflectivity surface – exactly what the 300 m module delivers against a 90% surface. Range dark asphalt or weathered concrete rather than a bright wall and you are buying the longer module to get the shorter module’s catalogue number. We work the same arithmetic from the selection side in spec range vs real range on the 100 m modules.

Published prices are the figures currently shown on the model pages; confirm current terms in writing.

Accuracy stays flat, repeatability is what degrades

All three H-series modules quote the same accuracy – ±10 cm below 10 m, 1% of reading above it – so nothing in the accuracy row tells you the 1,500 m part behaves differently from the 300 m one. The repeatability row does. Close in, all three repeat to ±5 cm. At the long end of their respective ranges, repeatability opens from ±10 cm on the LRF300H to ±50 cm on the LRF600H to ±100 cm on the LRF1500H.

Keep repeatability and accuracy as separate requirements in an evaluation plan. The published limits do not establish the distribution of measurements on a particular installation. Verify behavior against the intended surfaces, distances and operating conditions before relying on it in a control loop.

The serial frame changes width at 1,500 m, and parsers break

This is the integration trap that costs a week. The H-series outputs distance in centimetres over UART at 460800 baud, little-endian, behind a 5C frame header. On the LRF300H and LRF600H one reading is a 4-byte frame: header, two distance bytes, check byte. Two bytes of centimetres tops out at 65,535 cm – 655.35 m – which is why that format works to 600 m and no further.

The LRF1500H therefore uses a 5-byte frame with a 3-byte distance field, giving a 0-16,777,215 cm span. A reader tested against the 600 m module will silently mis-frame every packet from the 1,500 m module, because it consumes four bytes where five arrive. Branch on the model at configuration time; never assume a fixed frame length across this family. Our walkthrough of these frames is in serial protocol: frames and checksums.

Two items on the LRF1500H are logged as manual-internal conflicts on our side. We publish them instead of picking an answer, because a parser built on the wrong one fails in the field, not on the bench. Resolve both with engineering before you freeze a parser:

• Out-of-range sentinel. The 2-byte models return 65535 out of range. The LRF1500H manual writes its sentinel as “0xFFFF (16777215)” – two notations that do not describe the same value for a 3-byte field. Confirm which byte pattern the delivered firmware emits.
• Check byte on the wider frame. The manual’s own check-byte rule applied to its own printed example computes a different value from the printed check byte, which matches the 2-byte family’s result instead. The example appears not to have been recalculated for the 3-byte field.

Past 1,500 m the module is a different animal

The LRF3000A1 is not a longer H-series part. It comes from the 55 AA command family: 8-byte frames, 115200 baud default, results returned as the real value multiplied by 10, a status byte where 1 means the reading succeeded. It runs on 3.3-5 V, weighs 12 g, lists IP67 protection and standby power of ≤1 mW with enable high, or ≤350 mW with enable low.

The LRF3000A1 lists 3-10 Hz adaptive in normal mode and 1-10 Hz adaptive in long-range mode. Its response-time entry is ≤160 ms + 100-517 ms, labeled start-up + first ranging; retain that sequence when planning initialization. Its source lists typical beam divergence of ≤10 mrad and receiver field of view of ≈8 mrad. The H-model field of view of ≈4 mrad is a different source field and must not be substituted for beam divergence to calculate a transmitted spot or claim suitability for a particular surface. Accuracy is ±0.7 m to 100 m, then ±(0.7 + 0.003·d) m, about ±9.7 m at 3,000 m, with a ≥98% valid measurement rate and ≤1% false alarm rate. Note the 1 m minimum range, compared with 0.05 m on these three H-model records. If the application needs measurements below the selected module’s minimum, treat that as a separate system requirement; the table alone does not determine a complete sensing architecture.

Integration budget: the supply rail decides more than range does

The three H-model records list the same 33 × 34 × 18 mm dimensions and 20 ± 2 g mass. These shared fields do not establish a drop-in replacement: confirm the exact mounting, connector, cabling and configuration, and adapt the parser for the different frame lengths described above. The LRF3000A1 has a different documented footprint, supply rail and protocol family and needs its own integration review. Note too that our H-series manuals state the 9-36 V module supply but not the TX/RX logic-level voltage; ask for it in writing rather than inferring it from the supply rail.

All four are 905 nm Class 1 to IEC 60825-1; integrate one into a larger optical assembly and the classification has to be re-established for the finished product, as covered in What IEC 60825-1 Class 1 means for a 905 nm module. For host-side wiring and serial port setup on UAV platforms, the ArduPilot rangefinder documentation is the reference.

Frequently asked questions

Which long-range module should I pick for a dark or non-cooperative surface?

Size from the 10% reflectivity column, not the headline. For 200 m against a dark surface that means the LRF600H; for 300 m, the LRF1500H.

Can I reuse my LRF600H driver on the LRF1500H?

Not without a change. The LRF600H sends a 4-byte frame with a 2-byte centimetre distance; the LRF1500H sends a 5-byte frame with a 3-byte distance. Frame length differs; the LRF1500H out-of-range byte pattern must be confirmed because its manual contains the discrepancy described above.

Why does the 3,000 m module measure only a few times per second?

It is specified at 3-10 Hz adaptive in normal mode and 1-10 Hz in long-range mode. The three H-model manuals list 1 kHz or 50 Hz, switching automatically with echo strength. These are model-specific documented rates, not a guarantee of a fixed report interval on the host.

Send us your working distance, surface type and update rate and we will point at the right part – talk to our engineering team.