Optical Camera Communication as an Enabling Technology for Microalgae Cultivation

Abstract

Optical Camera Communication (OCC) systems have a potential application in microalgae production plants. In this work, a proof-of-concept prototype consisting of an artificial lighting photobioreactor is proposed. This reactor optimises the culture’s photosynthetic efficiency while transmitting on-off keying signals to a rolling-shutter camera. Upon reception, both signal decoding and biomass concentration sensing are performed simultaneously using image processing techniques. Moreover, the communication channel’s theoretical modelling, the data rate system’s performance, and the plant distribution requirements and restrictions for a production-scale facility are detailed. A case study is conducted to classify three different node arrangements in a real facility, considering node visibility, channel capacity, and space exploitation. Finally, several experiments comprising radiance evaluation and Signal-to-Noise Ratio (SNR) computation are performed at different angles of view in both indoor and outdoor environments. It is observed that the Lambertian-like emission patterns are affected by increasing concentrations, reducing the effective emission angles. Furthermore, significant differences in the SNR, up to 20 dB, perceived along the illuminated surface (centre versus border), gradually reduce as light is affected by greater dispersion. The experimental analysis in terms of scattering and selective wavelength attenuation for green (Arthrospira platensis) and brown (Rhodosorus marinus) microalgae species determines that the selected strain must be considered in the development of this system.

The Way to Modern Shutter Speed Measurement Methods: A Historical Overview

“…Let us denote the original signal by x(t), and the sampled signal by x s (k) = x(kT CAM ). Notice that due to (22), consecutive samples will have the following properties:…”

“…Let us suppose that the exposure time to be measured is approximately T exp ∼ = 1/1000 s, and we want to determine its exact value with 1% accuracy. The camera's sampling interval is T CAM = 1/30 s, parameter n = 5, thus, according to (22), T LED ∼ = 1/150 sec. If the reading accuracy ∆N exp ∼ = ∆N NLED ∼ = 2 = ∆N samples then, according to (29), the accuracy requirement can be written as h exp ∼ = ∆N 1 N exp + 1 N LED < 1%.…”

“…The ubiquity of smartphones, equipped with good quality cameras, stimulates the research of OCC systems. Here, the cameras are utilized as sensors, to receive visually coded information [18][19][20], and the value of the exposure time (among other factors) determines the data rate, the bit-error-rate, and the achievable lized as sensors, to receive visually coded information [18][19][20], and the value of the exposure time (among other factors) determines the data rate, the bit-error-rate, and the achievable communication distance [21][22][23]. In camera-based positioning systems, OCC is often utilized to allow beacon identification [24,25].…”

“…Let us denote the original signal by 𝑥(𝑡), and the sampled signal by 𝑥 𝑠 (𝑘) = 𝑥(𝑘𝑇 𝐶𝐴𝑀 ). Notice that due to(22), consecutive samples will have the following properties: 𝑥 𝑠 (𝑘) = 𝑥(𝑘𝑇 𝐶𝐴𝑀 ) 𝑥 𝑠 (𝑘 + 1) = 𝑥((𝑘+1)𝑇 𝐶𝐴𝑀 )) = 𝑥(𝑘𝑇 𝐶𝐴𝑀 + 𝑛𝑇 𝐿𝐸𝐷 + Δ𝑇) = 𝑥(𝑘𝑇 𝐶𝐴𝑀 + 𝑛𝑇 𝐿𝐸𝐷 + Δ𝑇).…”

Editorial to the Special Issue on “Visible Light Communications, Networking, and Sensing”

“…A simplified design of multi-channel transmitter using small 8 × 8 distributed LED array, based on grouping of LEDs, is proposed and tested for flicker-free transmission. C. Jurado-Verdu et al [12], in their paper on "Optical Camera Communication as an Enabling Technology for Microalgae Cultivation", show how the OCC technology can be used as a potential application in microalgae production plants. Authors proposed a proof-of-concept prototype consisting of an artificial lighting photobioreactor, which optimizes the culture's photosynthetic efficiency, while transmitting OOK signals to a rolling-shutter camera and analyzing node arrangements in a real facility, considering node visibility, channel capacity, and space exploitation.…”