New Probes Design
OLD 2006/7 probe specifications: (Elsaify)
• Probe Sensors measure [Pressure, temperature, 3D tilt + polar coordinate N/S (magnetic detector), resistance, strain, Humidity (water detector), light detector, battery voltage]
• Probes wake up from sleep mode for few times per day according to remotely reprogrammable schedule (for example 6, 12, 24, 48 times per day ) to record sensor data and store it in the probe memory
• Each probe should be able to store at least 5000 reading of sensors data (about 2 years when recording 6 times a day)
• Low power, probe battery life time at least 5 years theoretically
• The probe sensor data are sent to the base station daily
• Ability to remotely change the probe firmware
• Wireless ad-hoc networking for hopping the data between probes to the base station
• Retrieve all recorded data and network communication from lost probes when they join the network again even after very long time and also the ability to add more probes later to the system
• smaller in size than last version
• RF communication between probes and to the base station has a larger range, using 174MHz with more radio power than the previous version, (uses Gang's home made tuned antenna) 173MHz radio unit
Probe sensors resolution and ranges: (Elsaify)
Temperature: resolution: 0.03 C º, ranges: -40 to +150 Cº 14bit
Pressure: resolution: 0.5 psi, range 0 – 100 psi 8bit
Strain: resolution: range 0 – 1023 10 bit
Resistance: resolution: resolution 30K, range 30K – 30M 10 bit
Heading: resolution 1º, range 0 – 360 9 bit
Pitch: resolution 1º, range -90 to +90 8 bit
Roll: resolution 1º, range -90 to +90 8 bit
Light reflection: range 0 – 1023 10 bit
Humidity: resolution 1%, range 1 – 100 % 7 bit
Battery: resolution 50 mV 10 bit
+ 2 bits Flags
12 byte data + date 2 bytes + time 2 bytes = 16 byte per reading
New probe parts list: (Elsaify)
Microcontroller :Microchip PIC18LF8722
Crystal :10.0MHz
RTC : DS3231SN , (available 30) (15 available)
Transceivers modules support 173-174 MHz: Radiometrix TX1H (BiM1-173.250-10), 173.250MHz, 100mw, (got 30)
Serial RS232: MAX3319E
RS232 Serial Hub:MAX205E ,MAX235
Sensors:
Temperature: ADT7301ARMZ
3D tilt/ Polar coordinate N: 3-Axis Compass Sensor Set Honeywell HMC1055
Humidity: sensirion SHT75
Pressure: Honeywell 24PCGFM6G 250 psig
Water resistance: own made bridge to measure from 30K to 30M ohms
Strain: (stress) (aluminum), 120Ω, 2.1 gauge factor
Light detector: TSL251R, Photodiode IPL 10020 BW
White Light LED for reflectance measurements (Rapid 55-1542 NSPW510BS) 30mA (100 pulse) 3.6V (4 max) Use 330 Ohm for 6mA pulse of > 20ms
Amplifiers and buffers and transistors:
AD623
IRF7509
MAX9912EKA+
Power supply IC: MAX1672EEE
Power control ICs:
STC5NF20V
TPS73150DBVT
Batteries: three SL-360/P, AXIAL Battery , from SONNENSCHEIN, AA, , 3.6V, ,2.3Ah
Diodes: MBRS130LT3 Schottky
Leds (for debugging, and turned off before deploying): 6 LEDs: Vbat in, VCC Power, TX, RX, Sensor Power, BiM1 power
Capacitors:
Tantalum: 0.1Ω ESR, for power supply Ceramic: tolerance 5-10%, temp -55 to 85, 30ppm
Resistors: tolerance 0.1%, temp coeff
Coils/ Inductors: 10 uH for MAX1672.
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Radiometrix BiM1 potting The test results are disappointing. The potting epoxy degrades the performance of the the RF module. Almost 80-90% of the RF power was lost. The potting of antenna has much worse result.- GZ
Light Test with Ice and Till It depends on the relative positions of the LED and the photo receiver. When the LED is very close to the medium surface (ice or till), normally the voltage read from the photo receiver is 140mV higher in the ice than in the till. -GZ
White LED was better than green. Swapped to that now. Short on time with high current probably needed.
