The S-900-1 Sensor monitors temperature, relative humidity and wood moisture content. It combines environmental sensors, wireless transceiver, microcontroller, and battery into a compact enclosure designed to be embedded into structures at common points of moisture failure. Sensors are small enough to be mounted anywhere and their ultra long (15+ year typical) battery life mean the sensors can be mounted in areas that are inaccessible after construction is complete. Typically sensors are mounted on the lower corners of window and door frames, near flashed openings in roofs or exterior walls, at roof lines, under plumbing fixtures, under air conditioner condensate plumbing etc. The Sensor’s enclosure integrates 1.5” mounting standoffs such that when mounted to a surface the sensor is positioned well away from nails which may come through the surface during construction. Sensors are programmed to periodically wakeup from an ultra low power sleep state, take measurements, and open a communication session with the gateway such that the gateway can read the measurement data out of the sensor. The Gateway can also update the Sensor’s time of day, read out the Sensor’s stored GPS position1, and even perform an in-service firmware upgrade of the Sensor’s operating firmware.
Sensors
The S-900-1 Sensor incorporates highly accurate sensors which measure:
- The wood moisture content of the substrate the sensor is screwed into. Wood moisture content is measured from 7 to 40 percent and is fully temperature compensated. The data is calibrated to USDA standard Douglas Fir.
- Temperature is measured from -40 to +85 °C.
- Humidity is measured from 0-100% RH, non-condensing.
- Sensor battery voltage.
Wireless Link
The S-900-1 Sensor uses the 915 MHz frequency band which the FCC permits unlicensed use for Industrial, Scientific and Medical (ISM) purposes under FCC Part 15.247. Within that band the S-900-1 uses a technique known as Frequency Hopping Spread Spectrum (FHSS) to minimize the chance of interference with other devices sharing the same frequency band. The use of 127 different hopping channels helps establish an error free link between a Sensor and Gateway even in the presence of other devices sharing the same frequency band. The system uses both a Network Address (like your zip code) which is common to all Sensors and Gateways at a site and a Device Address (like your street address) which is unique to every Sensor and Gateway. The combination of addresses ensures a reliable, secure, error free link between Sensors and Gateways.
Microcontroller
The S-900-1 Sensor incorporates a powerful 5 MHz 16 bit RISC microcontroller with 8kB of reprogrammable FLASH memory. The sensor’s firmware image can be upgraded while the sensor is in service over the wireless link from the OmniSense FMS web site.
Battery
The S-900-1 Sensor utilizes the latest in Lithium battery technology and an ultra low current CMOS microprocessor to maximize battery life. Under typical operating conditions the battery is expected to last longer than 15 years making it possible to permanently install sensors inside walls, floors and roofs without requiring future access for battery replacement. Sensors also monitor their own battery voltage so that users can be alerted if a Sensor’s battery is approaching the end of its life.
Specifications
Parameter |
Min |
Typ |
Max |
Units |
Operating Temperature |
-40 |
25 |
85 |
°C |
Storage Temperature |
-40 |
|
85 |
°C |
Operating Humidity |
0 |
|
100 |
%RH2 |
Operating Voltage |
2.5 |
|
3.7 |
Vdc |
Operating Current Active |
|
27 |
|
mA |
Operating Current Standby |
|
3.0 |
|
uA |
Temperature Measurement range |
-40 |
|
85 |
°C |
Temperature Measurement Accuracy |
|
±0.53 |
±2 |
°C |
Wood Moisture Range , USDA Douglas Fir |
7 |
|
40 |
% |
Humidity Measurement Range |
0 |
|
100 |
%RH |
RH Absolute Accuracy |
|
±3.5 |
±5.0 |
%RH |
Battery Type |
|
ER14505 |
|
|
Battery Voltage |
|
3.6 |
|
Vdc |
Battery Capacity |
|
2.0 |
|
Ah |
Battery Life |
|
15 |
45 |
Years4 |
Sensor Length |
|
2.4 |
|
Inches |
Sensor Width |
|
1.6 |
|
Inches |
Sensor Height |
|
2.55 |
|
Inches |
Sensor Weight |
|
2 |
|
ounces |
Reporting Period |
|
60 |
|
minutes |
Wireless Frequency Band |
902 |
|
928 |
MHz |
Wireless Transmit Power |
|
10 |
|
dBm |
Wireless Range |
|
1006 |
|
m |
Wireless Channels |
|
127 |
|
Channels |
Wireless Channel Separation |
|
200 |
|
KHz |
1 Permanently stored by the OmniSense Installer at time of installation
2 Non-condensing
3 @ 25 °C
4 @ 25 °C and a 1 hour reporting interval. Theoretical calculations of battery life are used to predict the maximum 45 year life under these conditions.
5 Excludes antenna
6 Varies based on many factors including the presence of obstacles such as concrete walls and interference from other electronic equipment