Table of Contents
Wireless Link-Budget Calculator
Calculate a rough estimate, with our handy tool
A Link-Budget is the total amount of power between a transmitter and receiver. By taking this Link-Budget and factoring in the loss of power through free-space and other obstacles such as walls, it’s possible to roughly estimate the effective transmission distance and to gain an understanding of how various obstacles and other changes affect a signal. Of course, wireless signal strength calculations aren’t really so simple, factors such as antenna directionality, design efficiency, reflection, scattering, diffraction and weather conditions all play a significant role.
The below calculator will provide an extremely-rough estimate of signal strength based on free-space proportion and obstacles only, but can be incredibly useful in helping to understand the affect various obstacles will have on the range of a wireless product.
Example 1 – LM540 Bluetooth 2.1 EDR + 2dBi Antenna (SPP) x 2 at Olympic Rowing Lake (Dorney Lake)
Confident in the capabilities of our LM540 USB-powered Bluetooth 2.1 EDR Adapter, LM Technologies set-off to prove its adapters in a real-world scenario by utilising the long straight at Dorney Lake, which provides Olympic-class distance measurements. A Pair of LM540 adapters, both equipped with 2dBi antennas, achieved a distance of 787M (murky weather, no rain). In this test, there were no notable obstacles and the adapters and their respective laptops were held at around waist height.
Note: Achievable bit-rate will gradually reduce over the transmission range.
Example 2 – CSR101x Compact Reference Design Bluetooth 4.0 SMART (Low-Energy)
Utilising a reference design compact module equipped with a CSR101x Bluetooth SMART (Low-Energy) IC, chip vendor CSR was able to achieve between 30 and 50M range in open-space, when limiting transmission power on the chip to 0dBm.
These modules typically feature a sensitivity of -92.5dBm with dynamically adjustable transmission strengths, ranging up to 9dBm.
Note: Compact modules with onboard antennas feature additional design challenges when compared with their big brothers. Noise from other components can play a greater role and the smaller effective ground plane of a miniaturised module can reduce performance.