1. RF Monitoring System – Proposal Magnus Jobs

2. Desired System Criterions Pulse Measurements Good Coverage Modular
User Friendly
Inexpensive
Alarm Indication
Wireless
Good Lifespan if Battery Powered

3. Advantage of Multiple Receivers
Multi-Scattering
Indoors environment, up to ~30 dB variation
Significant fast & slow fading expected
Multiple receivers reduces chance of measuring in fading null
Pictures Illustrate how signal levels can vary in a scattering environment
Variation in
signal strength
Transmitter

4. System Description Specifications Dynamic Range: -34 to +14 dBm
Unfiltered: 0.1 to 1000 MHz
Filtered: Ex: 334 to 360 MHz
Average Power Consumption: 123 to 515 uA
Fixed or Battery Powered Operation
Estimated Lifespan 0.3 to 1.1 year
3xAAA Batteries, USB or 24V External
Sample Rate: 2 kHz (adjustable)
Min Pulse Length: 0.5 ms (adjustable)
Data Rate: 0.01 to 10 Hz (adjustable)
Range: 100m (Realistic Estimate)
RS232 & USB Interface to Master
Acoustic Alarm Signal
OLED Display
Direct Shottky based detectors
Mixers omitted due to power constraints
3 Inputs for different configurations:
Polarization
Spatial
Frequency Band
USB
RS232 uC
TRX
Display
RFPM
Buzzer
Button IO
Regulators
LED

5. Power-Meter Concept Drawing
Top-mounted display button
White OLED Display
Red reset button
5-Pin external connector
3-Meter Inputs
TRX Antenna
60 mm
100 mm

6. Schematic Layout Battery Holder 44 mm Board 52 mm Layout 2-Sided board
Single Sided Mounting
Battery holder soldered to PCB
Battery Holder
52 mm
44 mm
Board

7. Schematic

8. Estimated Power Consumption
Total Power Consumption
Sampling Rate: 2000 kHz (0.5ms Pulses Min)
ITot,3 Detectors = 65+( )/0.7 = 579 uA
ITot,1 Detector = 65+( )/0.7 = 299 uA
Sampling Rate: 1000 kHz (1.0ms Pulses Min)
ITot,3 Detectors = 65+( )/0.7 = 369 uA
ITot,1 Detector = 65+( )/0.7 = 228 uA
Sampling Rate: 500 Hz (2.0 ms Pulses Min)
TX Freq: 0.2 Hz
ITot,3 Detectors = 65+( )/0.7 = 327 uA
ITot,1 Detector = 65+( )/0.7 = 187 uA
V-Regulator: REG
IQ = 65uA
Efficiency: Assume moderate 70%
RS232
Off in slave mode (hardwired)
IQ = 0 mA
USB
Off (self powered)
Display
Normally Off (hardwired)
Transceiver: MRF89XA
Running: 200 kbps, 1Hz TX, 20 Byte Packages
Package Overhead 12 Byte
RX for 200 ms every 60 seconds
TX Time = (20*8)/200e3 = 0.8 ms
TX Start-up Time = 1.5 ms
ITX = 16 mA
ITX,Average = 16*2.3e-3=36.8 uA
IQ,Sleep = 0.1 uA
IRX = 3.5 mA
IRX,Average = 3.5e-3*3.3e-3 = 11.7 uA
ITRX,Total = = 48.6 uA
Micro-Controller: Microchip 16-bit 24F16KA102
Running: 4 MIPS (Internal RC)
ADC Sample Time: ~40 us
Sampling 3 Channels at 2 kHz
Total Sampling Time = 40*3*2000 = 240 ms
IQ = 950 uA
ISleep = 15 uA
IQ,Avg, 3 Detectors = 950 * 120e-3 = 228 uA
IQ,Avg, 1 Detector = 950 * 120e-3 = 76 uA
ITot,3 Detectors = = 243 uA
ITot,1 Detector = = 91 uA
RF-Detector : LTC5507
Off (self powered)
Sampling Rate: 2000 kHz
Sampling Time: 20 us
IQ = 550 uA
IQ, Sleep = 2 uA
IQ,Avg, 3 Detectors = 550*20e-6*3*2e3 = 66 uA
IQ,Avg, 1 Detector = 550*20e-6*2e3 = 22 uA
ITot,3 Detectors = 66+2 = 68 uA
ITot,1 Detector = 22+2 = 24 uA
Estimated Lifespan (Battery): 0.27 to 0.8 year

9. Possible Life-Span Improvements
Using a LDO instead of a switched regulator gives about 70 % efficiency running of same 3xAAA stack
Microchip MCP1700 has similar sized footprint (SOT-23) and 1/3 price
Quiscent Current of MCP1700 ~1.6 uA
Improvement of 1.6 uA Quiscent Current
Sampling Rate: 2000 kHz (0.5ms Pulses Min)
ITot,3 Detectors = 1.6 +( )/0.7 = 515 uA
ITot,1 Detector = 1.6 +( )/0.7 = 235 uA
Sampling Rate: 1000 kHz (1.0ms Pulses Min)
ITot,3 Detectors = 1.6 +( )/0.7 = 305 uA
ITot,1 Detector = 1.6 +( )/0.7 = 165 uA
Sampling Rate: 500 Hz (2.0 ms Pulses Min)
TX Freq: 0.2 Hz
ITot,3 Detectors = 1.6+( )/0.7 = 263 uA
ITot,1 Detector = 1.6 +( )/0.7 = 123 uA
Improvement
11%
21%
17%
28%
19%
34%
New Estimated Lifespan 0.3 to 1.1 year

10. Flow-Chart: Slave Configuration
Initialize
Master?
RX Broadcast
Master Found?
Sleep
Set ID/Channel
Reconfig
Power Limit?
Send Data
Alarm Mode
Master Mode
Reset?
Display?
Update Display
Alarm Sent?
Enable Sampling
Sampling
RX Config?
TX Data?
Enable RX
Measure Battery?
Sample Battery
Config Receive?
TX Reply
Timeout?
Yes No
Reply?
TX Join Req

11. Flow-Chart : Master Configuration
Initialize
Master?
Slave Mode No
Yes
RX Mode
Data
Received?
Add Data
TX Broadcast
Slave Found?
Add To List
TX ID/Channel
Power Limit?
Alarm Mode
Display?
Update Display
Measure Battery?
Sample Battery
Broadcast?
TX Config?
TX Config
Ack Received?
Slave in list?
Mark Alive
Response Timeout?
Cull Slave List
Mark Unknown
Sampling
UART

12. Bill Of Material (BOM) – Simplified
Bill Of Material (BOM) – Single Component Purchase – Simplified Version
All electronic components available from Farnell except Display
Cost of PCB assumed an order of 10 pieces
SMA connectors not included due to high price at Farnell
Some components could still have better priced alternatives
Components
Lumped Elements
38,5
Regulator
REG71050DDCT
15,67
SWS001
12,56
Op-Amp
L78L05ABUTR
2,35 uC
PIC24F16KA102-I/ML
24,93
LDO 24V
MCP6001UT-I/OT
2,84
Crystal
QC32
16,69
Transceiver
MRF89XAT-I/MQ
20,51
FTDI
FT230XS
19,51
RS232
ST3232BDR
6,31
RFM
LTC5507ES6PBF
34,18
USB Connector
MINI-USB
10,85
Sub Total:
273,26
Other
Display
SSD1306-OLED White
Ebay 50
Casing
Farnell
46,2
Antenna
26,35
PCB (Per piece if order total 10 boards)
Cogra
235
Sub Total:
357,55
Estimated Prototype Cost: ~650 SEK per Piece

13. Conclusion Highlights Supply or battery powered
3 – Channels, 50 dB dynamic Range
Multiple Sensor System
RS232 Interface to Master
Self Configuration
Remote Configuration of Slaves
Current State
Concept Prepared
Schematic Finished
PCB Layout Finished
BOM Finished
Most Firmware Already Done
Functional Flow-Chart Finished
Proposed Concept