Tools / Skylark field guide

A small workbench for your receiver.

Plan a setup, explore range geometry, understand cable loss, inspect a snapshot and find the next diagnostic check.

Documentation reviewed 19 Sep 2026Edition 01

All calculations and pasted JSON stay in this browser. These are educational models and basic diagnostics, not receiver certification or aviation instruments.

01 / Find a starting point

Your receiver plan

Choose the work you want to maintain. Existing equipment takes priority over installing something new.

Already receiving? Keep the decoder and add a compatible feed. Starting fresh? Compare the four documented installation routes.

02 / Understand the geometry

How far is the horizon?

A taller receiver and a higher aircraft can see farther over a smooth Earth. Terrain, buildings, refraction and receiver sensitivity are outside this model.

368.0 km198.7 nautical miles

At 10 m receiver height and 10,000 m aircraft height. Rounded geometric model, not measured reception.

Calculated smooth-Earth geometric horizon distance for a receiver at 10 metres and aircraft heights from zero to 12,000 metres. Distance increases with height. Model excludes terrain, refraction and reception limits. A numeric table accompanies this graph. Original Skylark illustration; schematic unless labelled as a computed model.

Model, assumptions and numerical table

We use a spherical Earth of radius R = 6,371,000 m. Arc distance is R × [acos(R / (R + receiver height)) + acos(R / (R + aircraft height))]. Divide by 1,000 for kilometres and 1.852 for nautical miles. Heights are above the same ideal sphere, not automatically your surveyed elevation or a pressure altitude.

Receiver	Aircraft	Ideal distance
10 m	0 m	11.3 km
10 m	100 m	47.0 km
10 m	1,000 m	124.2 km
10 m	3,000 m	206.8 km
10 m	6,000 m	287.7 km
10 m	10,000 m	368.0 km
10 m	12,000 m	402.0 km

03 / Interpret a specification

What does cable loss cost in power?

Enter total loss in decibels at your operating frequency. Read the cable manufacturer's figure for the actual length, then account for specified accessory losses. This does not calculate range.

50.1%of input power remains after 3 dB loss

This is a power ratio, not a prediction that range halves.

The power fraction decreases exponentially as loss in decibels increases. Three decibels leaves about half the power and ten decibels leaves ten percent. This is a power calculation, not a range calculation. Original Skylark illustration; schematic unless labelled as a computed model.

Formula and reference values

Remaining power percentage = 100 × 10^{−loss / 10}. This follows the definition of a power ratio in decibels.

Loss	Power remaining
0 dB	100%
3 dB	50.12%
6 dB	25.12%
10 dB	10%
20 dB	1%

04 / Inspect your own snapshot

Is this aircraft data fresh?

Inspect a readsb-style aircraft.json snapshot locally. Nothing is uploaded or stored. The tool checks structure, coordinates, source labels and basic ages. It does not authenticate a receiver, decode messages or reproduce any network's full validation. [1]

05 / Find the next check

Where does the evidence stop?

Choose the symptom. Work on the first failing part of the chain, not every part at once.

The full troubleshooting guide works without JavaScript. Download the station notebook to keep a private record of changes.

Sources and review notes

Documentation reviewed on 19 September 2026. Links lead to the source owners. Versions, account benefits and service terms can change. Hardware installation is not independently bench-tested for this edition.

readsb: JSON output formatsMaintainer specification. Field meanings and units. Mutable development-branch documentation.

How we check and maintain this guide