Signal Strength Simplified

Introduction

Many of the items we find useful, enjoyable, and often-times necessary are provided by wireless communication. Consider the GPS service we use to find our destination, satellite television, and our cell phone, which is used for practically everything. These services are available to us using wireless signals, invisible airwaves transmitting little pieces of data through the air.

Wireless signals are generated when energy travels through a piece of metal, such as an antenna, and waves are formed around that antenna. How far those waves travel depends on the strength of the energy being generated. A device that sends out a wireless signal is a transmitter, and the device that picks up the signal is the receiver. An excellent example of this would be your car radio; the radio station has a transmitter that projects a wireless signal to many receivers, one being your car stereo.  Some devices can both send and receive these transmissions, sometimes called a transceiver, such as your cell phone. COBRA’s 18R and 18R2 controller, 18M, 36M, and 72M firing modules and Audio Box are all transceivers, utilizing omnidirectional antennas (360° coverage around the device).

Signal Strength

Signal strength determines the range that a COBRA firing module can communicate wireless signals with the COBRA 18R or 18R2 controller. COBRA transmits on the 2.4GHz band whose wireless signal range is measured in dBm and will fall between 0 and -99 dB with 0 being perfect and -99 the worst. The reliable range is between 0 and -75 dBm. Any dBm values between -75 and -99 are likely to fire but are not within the recommended range. The range is easily tested on all COBRA devices, including controllers, firing modules, and the Audio Box. It is important to realize the signal range does not decrease linearly.  A signal range indicating -40 dB at 100 feet (or 30 meters) will not be -80 dB at 200 feet (or 60 meters) but will be -45 dB at 200 feet (60 meters), as shown below.

Physical barriers may block or weaken a wireless signal and should be considered when placing your COBRA equipment.  The best advice for alleviating this potential concern? Is to have direct line-of-sight (LOS) between your COBRA controller and the COBRA module after placement.  LOS, overly simplified, is being able to visually see your COBRA module from the location of your COBRA controller. Clear LOS helps to ensure a robust wireless signal between the two devices, allowing each transceiver to send and receive data at lightning speeds, as designed. Although LOS has traditionally required a considerable amount of thought and planning in wireless communication, COBRA’s utilization of MESH signal technology, as discussed below, significantly mitigates much of the concern surrounding LOS. MESH networks are designed for non-line-of-sight configurations, with each module improving signal within your COBRA network.

Think about where you may be using your COBRA controller, firing modules, and Audio Box: a football field or stadium, on a barge, an area surrounded by woodland, a downtown park. If your signal is not as strong as desired, consider what items may be causing a disruption and re-position devices, keeping in mind nature’s natural barriers such as trees, leaves, and boulders which can cause similar interference as buildings and other man-made structures. According to the US National Institute of Standards and Technology, certain materials can interfere with wireless transmissions more than others (listed in order of signal loss potential, drywall and plywood coming close to zero):

• Concrete
• Brick
• Masonry block
• Lumber
• Glass
• Drywall
• Plywood

MESH Signal Technology (firmware 5.0 and higher)

Quality line-of-site (LOS) is an important consideration when placing your COBRA controller and a COBRA firing module. However, using the COBRA MESH technology, LOS is less critical as COBRA’s firing modules and Audio Box act as wireless repeaters and transmits the data directly between each other without needing a direct visual line to the controller, hence forming a MESH network. 

The real allure of a MESH network is that it works seamlessly and automatically without any user complexity.  With a MESH network, the wireless signal can now be transmitted around trees, buildings, hills, and more. COBRA’s modules and Audio Box have been developed to select the optimum path between each device with no single module being dependent on any other.  If the road to one is not the best, the data will immediately be redirected to the next module establishing the fastest, most reliable connection possible between your COBRA devices. To maintain timing, COBRA automatically calculates processing time, network latency, and other factors to calculate time lost over "hops". These calculations are performed using lightweight custom algorithms that sit above several layers of both custom and native MESH technology to achieve an optimal balance of reliability and accuracy.

Shooting Over Water

COBRA systems have been used successfully in thousands of shows fired over water. This includes transmitting wireless communications over water to land such as crossing a river as well as firing directly over water such as a barge show. Without using any signal boosting or MESH functionality, the longest range achieved was over 1.36 miles. Using the COBRA Booster and MESH, COBRA can achieve significantly longer results. Some have claimed that most of the 2.4 GHz wireless frequency band is absorbed by water, this is not correct. While all wireless signals have some absorption to water the effect on 2.4GHz is negligible and not enough to impact the functional performance of the COBRA system.

Stadium Shooting

COBRA systems are used around the world in professional stadiums for all types of venues including but not limited to sporting events and concerts. This includes outdoor college and NFL stadiums, indoor NBA and NHL, and professional international stadiums around the world. While stadiums employ challenges with signal, including barricades and achieving timing between in-field and outside the stadium aerial shooting, COBRA's unique use of MESH and signal accessories allow for highly reliable stadium use. For any questions on how best to use COBRA within a stadium shoot, please email us at help@cobrafiringsystems.com.

Conclusion

Signal strength is fundamental in wireless communication and should be tested with your COBRA system before an exhibition.  It is equally important to remember the final location of your devices will be the most significant determining factor of signal strength; your backyard test will have different results than the ball field you find yourself shooting from.  And by utilizing MESH networking (firmware 5.0 and higher), COBRA has alleviated the need for LOS on all firing modules and improved the overall wireless network that comprises your COBRA system. Pay attention to your surroundings and make basic adjustments to the equipment location, as needed, to make sure you have the proper signal strength and MESH network laid out to provide a low stress and successful display.