RF Monitoring System – Proposal Magnus Jobs

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

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

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

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

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

Schematic

Estimated Power Consumption Total Power Consumption Sampling Rate: 2000 kHz (0.5ms Pulses Min) ITot,3 Detectors = 65+(48.6+243+68)/0.7 = 579 uA ITot,1 Detector = 65+(48.6+91+24)/0.7 = 299 uA Sampling Rate: 1000 kHz (1.0ms Pulses Min) ITot,3 Detectors = 65+(48.6+129+35)/0.7 = 369 uA ITot,1 Detector = 65+(48.6+53+13)/0.7 = 228 uA Sampling Rate: 500 Hz (2.0 ms Pulses Min) TX Freq: 0.2 Hz ITot,3 Detectors = 65+(19.2+129+35)/0.7 = 327 uA ITot,1 Detector = 65+(19.2+53+13)/0.7 = 187 uA V-Regulator: REG710-3.3 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 = 36.8 + 0.1 + 11.7 = 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 = 228+15 = 243 uA ITot,1 Detector = 76+15 = 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

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 +(48.6+243+68)/0.7 = 515 uA ITot,1 Detector = 1.6 +(48.6+91+24)/0.7 = 235 uA Sampling Rate: 1000 kHz (1.0ms Pulses Min) ITot,3 Detectors = 1.6 +(48.6+129+35)/0.7 = 305 uA ITot,1 Detector = 1.6 +(48.6+53+13)/0.7 = 165 uA Sampling Rate: 500 Hz (2.0 ms Pulses Min) TX Freq: 0.2 Hz ITot,3 Detectors = 1.6+(19.2+129+35)/0.7 = 263 uA ITot,1 Detector = 1.6 +(19.2+53+13)/0.7 = 123 uA Improvement 11% 21% 17% 28% 19% 34% New Estimated Lifespan 0.3 to 1.1 year

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

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

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-32005-201 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

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