+ if there is metal behind the wireless sensors, this will improve the ability of the gateway to connect with the sensor and aid the sensors with connecting to the gateway, becuase the RF signals will bounce off the the metal. 

+ deploying the HTC Gateway with metal behind it can help improve the range of communications with the sensors.  The radio waves from the sensors will reflect off of the metal while communicating with the gateway.

+ deploying the HTC Gateway at a higher elevation can aid the radio signals to travel to and from the sensors with a clear line-of-sight

+ position the HTC Gateway so that both of its' antennas are facing the sensors or consider placing the HTC Gateway in an area that is the center of all of the deployed sensors.

+ In cases where a sensor is not being seen by the gateway, changing the sensor's orientation to horizontal vs. vertical can make a difference.

What is atmospheric attenuation?

"the reduction in the intensity of the wireless signal strength as it passes through the Earth's atmosphere."

This can be caused by a number of factors, including:

 - humidity, rain, and snow will diminish the wireless signal strength

- human bodies, being 60% water weight, positioned between the gateway and the sensors will diminish the wireless signal strength

- welding near or between the gateway and the sensors, or a malfunctioning electrical transformers, or "noisy" electronics in the area will interfere with the wireless signals

 - motors all can cause wireless interference, becuase they generate electromagnetic interference (EMI)

- thick concrete, concrete with metal reinforcement, and wet curing concrete all will weaken the wireless signal.              

 - Wake often suggests hanging the wireless logger portion of the sensor outside of the concrete, so that you gain wireless signal range and so that you only sacrifice the temperature sensor probe with each placement. 

- Try moving the HTC Gateway closer to the sensors, or if the monitoring period is over, remove the temperature sensor cable and move the sensors near the HTC Gateway so that the stored temperature data will upload at the next interval

- the loggers used with HardTrack will hold up to 10,000 temperature readings per sensor, so if interference is temporary, the data will upload as soon as the sensors connect to the gateway.

- Run "Scan for Sensors" in HardTrack so that you can see all of the sensors in the area that the HTC Gateway can connect with.  This may help you with determining what the issue is.

- Consider adding an additional HTC Gateway to your project area.  When more than (1) HTC Gateway is placed in a project site, HardTrack will automatically determine which gateway can communicate with each sensor.

- If you have (2) HTC Gateways at your project site, under optimal conditions, HardTrack will be able to communicate with sensors in an area up to 2,000 feet/600 meters by 1,000 feet/300 meters, etc.