NJM0071-027-028916.5 MHz Data Acqusition Transciever

NJM0071-029 MicroWIS™ User Guide Invocon, Inc. Innovative Concepts in Systems Engineering 2Micro-Wireless Instrumentation System NJM0071-029 © Copyright 2000 Invocon, Inc. DRAFT COPY 19221 I-45 South, Suite 530 Conroe, TX 77385 FCC Notice: The MicroWIS™ Sensor Unit and PC Interface Unit of the MicroWIS system are subject to the following certification. This device complies with part 15 of the FCC Rules. Operation is subject to the f o llo wing two co nditio ns: (1) This device may no t cause harmf ul interf erence, and (2) this device must accept any interference received, including interference that my cause undesired operation. CAUTIONARY NOTE TO USER: Changes or modifications to the any piece of equipment in the MicroWIS system are not expressly approved by the manufacturer and could void the user’s authority to operate these units under the Regulations promulgated by the Federal Communications Commission. 3Micro-Wireless Instrumentation System NJM0071-029 DRAFT COPY© Copyright 1999 Invocon, Inc. 19221 I-45 South, Suite 530 Conroe, TX 77385 Document Overview This document will lead you through the steps necessary to collect and view data using the MicroWIS Units. The MicroWIS is manufactured by Invocon, Inc. For more information about this product and other Invocon products please refer to the Contact Information section at the end of this document. Table of contents Page 1.0 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4 2.0 Installation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 3.0 Features . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 6 4.0 A Sample Setup . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9 5.0 About the Chart program . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9 6.0 View data file with other programs . . . . . . . . . . . . . . . . .. . . 10 4Micro-Wireless Instrumentation System NJM0071-029 © Copyright 2000 Invocon, Inc. DRAFT COPY 19221 I-45 South, Suite 530 Conroe, TX 77385 1.0 I NT RODUCT ION 1.1 S YSTEM DESCRIPTION The Micro-Wireless Instrumentation System (MicroWIS) is a wireless data acquisition network to measure and transmit temperature data via a wireless link to a transceiver plugged into a PC. A Windows 95 Graphical User Interface allows easy installation, programming, and downloading of data from each unit. The system measures and transmits two temperatures, one on the MicroWIS unit itself, and an external temperature via a two-wire resistive temperature device. A maximum of 32 units, each with a unique node ID can coexist in a single network. A MicroWIS unit’s sample/transmit rate is programmable by the user via setup commands sent from the PC to the transceiver which broadcasts the commands to the units. The measured temperature data is packetized, encoded and sent to the transceiver which decodes and time stamps the data, handles the communication protocol, and sends the data to the PC for plotting and logging. Received temperature data packet is checked and acknowledged for correctness, otherwise the unit will retransmit the data. The remote temperature sensing units will take measurements of both internal and external temperature at sampling intervals according to the latest setup command received from the controller. The external and internal temperatures will be represented with 14-bit and 10-bit resolution respectively. The data packet in addition to these data will include error detection bits and 8-bits to uniquely identify each node. With 8 bits dedicated to the ID field, up to 256 unique IDs are available which are assigned serially and hard coded to the unit during manufacturing and could not be changed by the user. This necessitates reuse of the assigned IDs. The responsibility for preventing a network configured with identical IDs is with the user. This type of setup would result in multiple units with identical IDs to be seen by the controller as a single unit. Such as setup will result in data, which will be hard to interpret because it will be shown as if coming from the same unit. Another concern would be the calibration file which is organized and identified by the unit’s ID. The setup command which basically sets the sample/transmit rate of the remote units, is global. There is no individual or group setting of the sample/transmit rate. Since a network can accommodate up to 32 remote units and they are all set to the same sample/transmit interval, this may imply a high probability of packet collisions at the controller. However, even though the intervals are identical, the transmissions are made asynchronous and randomized by setting the unit’s internal co unters ref erence to a unique start time during manuf acturing. Every senso r unit’s internal counter are shipped with a setting equivalent to a default rate of 1sample/minute, and they are transmitting a fixed size packet at a fixed transmission rate of 111000 bps. This essentially limits the transmissions to bursts of roughly 1.1 milliseconds. 5Micro-Wireless Instrumentation System NJM0071-029 DRAFT COPY© Copyright 1999 Invocon, Inc. 19221 I-45 South, Suite 530 Conroe, TX 77385 However, this alone doesn’t eliminate the possibility of collisions at the controller (all sensor units are transmitting asynchronously at the same carrier frequency of 916.5MHz in half-duplex mode). Collision will result in errors on the received packets from the units. The unit’s transmissions require acknowledgment from the controller, If they don’t receive the acknowledgment they will retransmit up to 3 times, but every time their transmit start time will be delayed to minimize the collision probability. The delay duration which is in milliseconds range will be calculated based on a hashing function with the unit’s ID as input to randomize the delays. The sensor units have an internal timer for controlling the wait duration to receive the acknowledgment, which…

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Invocon, Inc. 19221 I-45 South, Suite 530 Conroe, TX 77385 The location of the label on the MicroWIS Sensor Unit will be on the cable of the unit in a font readable without magnification as shown below: FCC ID: NJM0071-027-028

NJM0071-027-028 © Copyright 2000 INVOCON, INC. All Rights Reserved. 19221 I-45 South, Suite 530 Conroe, TX 77385 Theory of Operation MicroWIS Sensor Unit The MicroWIS Sensor Unit takes a temperature sample at a periodic rate based on an internal counter. At power up, this sample rate is 1 sample per minute (default rate). When the periodic timer has not timed out, the sensor unit is in its low power mode. In this mode, the radio and analog front end are not powered. While in this low power mode, the microprocessor is also in its lowest power consumption mode in which only the periodic timer is running. This timer is based on a 32.768 kHz crystal. For sample rates less than 15 seconds, the microprocessor wakes up, acquires a temperature sample, powers on the radio, and transmits the data packet. For sample rates greater than 15 seconds, the processor wakes up briefly to update its sample rate counter in 15-second intervals and resumes its low power consumption mode. When the desired interval time has elapsed, the processor acquires a temperature sample, and transmits the data packet. During each sample acquisition, the front-end power is enabled and a temperature measurement is acquired. During the time that the temperature measurement is being acquired, the radio remains in a non-powered condition. Once the temperature sample has been acquired, the front-end power is disabled, the radio power is enabled, and the sample is transmitted as part of a data packet. The base-band data packet is sent from the microprocessor with a base-band bit time of 9 microseconds. The radio circuit modulates the message as an ASK modulated RF signal at 916.5 MHz. As soon as the entire data packet has been transmitted, the radio is put into receive mode (for 1.7 milliseconds). The processor then monitors the receiver for receipt of an acknowledgement message transmitted from the PC Interface Unit. Each acknowledgment message is transmitted in 1.1 milliseconds. If the MicroWIS Sensor Unit receives a valid acknowledge message from the PC Interface Unit, it will update its sample rate with the sample rate contained within the acknowledge message and will begin to acquire temperature samples at that new rate. If there is no successful acknowledge, the sensor unit will delay for 20 mS and re-transmit the data packet and will wait for the PC Interface Unit acknowledge again. If there is no successful acknowledge from the PC Interface Unit after 3 re-transmits, the MicroWIS Sensor Unit will enter its low power mode and will wait for the next sample time using the current sample rate.

NJM0071-027-028 MicroWIS System Timing The MicroWIS sensor unit sample rate is programmed via the Personal Computer Interface Unit (PCIU). The MicroWIS sensor unit can be programmed using the graphical user interface to acquire and transmit a sample at the following intervals (seconds): 1 2 4 8 16 30 60 120 240 48096018003600 The MicroWIS sensor unit will send its acquired temperature to the PCIU after a random delay of 12 to 25 milliseconds. This transmission has a duration of 1.134 milliseconds. The sensor unit then switches to “receive” mode for 1.60 milliseconds to listen for an acknowledge. If no acknowledge is received the sensor unit initiates a retransmit sequence that randomly delays for 12 to 25 milliseconds, then retransmits the acquired temperature. This sequence can occur up to four times for each temperature sample. The PCIU acknowledge transmission also has a duration of 1.134 milliseconds. Up to 32 sensor units may communicate with the PCIU. The command to set the sample rate is included in the communication acknowledge message. The sensor unit changes the sample rate, if instructed to do so, immediately after decoding the acknowledge message. The following chart shows timing for valid reception on the first transmission of the sensor unit: Sensor Unit Random Delay Transmit Receive No RF.............. PCIU Listen Receive Acknowledge No RF.............. Timing 12.0 to 25 mS 1.134 mS 1.60 mS Programmed Interval If the PCIU acknowledge message is not received by the sensor unit, the sensor unit will attempt to retransmit after a random delay. The retransmit occurs a maximum of three times. The next chart shows the sequence for an acknowledge message NOT received after the first transmission but successfully received after the second transmission. Sensor Unit Random Delay Transmit ListenRandom Delay Transmit Receive PCIU Listen ReceiveAcknowledge Listen Receive Acknowledge Timing 12.0 to 25 mS 1.134 mS 1.60 mS 12.0 to 25 mS 1.134 mS 1.60 mS

FCC ID# NJM0071-027-028 Professional Testing (EMI), Inc.Page 2 of 15 Project Number: 00457-10 Prepared for: INVOCON, INC. 19221 IH45 South, Suite 530. Conroe, TX 77385 By Professional Testing (EMI), Inc. 1601 FM 1460, Suite B Round Rock, Texas 78664 June 2000 CERTIFICATION Electromagnetic Interference Test Report INVOCON, INC. MicroWIS Sensor Unit (Intentional Radiator Portion) FCC ID# NJM0071-027-028 Professional Testing (EMI), Inc.Page 3 of 15 Table of Contents Title Page....................................................................................................................................1 Table of Contents........................................................................................................................2 Certificate of Compliance............................................................................................................3 1.0EUT Description.................................................................................................................4 1.1EUT Operation....................................................................................................................4 2.0Electromagnetic Emissions Testing......................................................................................4 2.2Test Criteria....................................................................................................................5 2.3Test Results.....................................................................................................................5 3.0Occupied Bandwidth Measurements....................................................................................5 3.2Test Criteria....................................................................................................................6 3.3Test Results.....................................................................................................................6 4.0Antenna Requirement..........................................................................................................6 4.1Evaluation Procedure.......................................................................................................6 4.3Evaluation Results...........................................................................................................7 5.0Modifications to Equipment.................................................................................................7 6.0List of Test Equipment........................................................................................................7 Figures Figure 1: Radiated Emissions Test Setup.....................................................................................8 Appendices Appendix A: Fundamental Emissions Test Data.........................................................................10 Appendix B: Spurious Emissions Test Data...............................................................................12 Appendix C: Occupied Bandwidth Test Data.............................................................................15 THIS REPORT SHALL NOT BE REPRODUCED EXCEPT IN FULL, WITHOUT THE WRITTEN APPROVAL OF PROFESSIONAL TESTING (EMI), INC. 1601 FM 1460, Suite B Round Rock, Texas 78664 512/244-3371 Fax 512/244-1846 Applicant:INVOCON, Inc. Applicant’s Address: 19221 IH45 South, Suite 530. Conroe, TX 77385 Model:MicroWIS Sensor Unit Serial Number:N/A Project Number:00457-10 Test Dates:08 March 2000, 09 March 2000, and 17 May 2000 I, Jeffrey A. Lenk, for Professional Testing (EMI), Inc., being familiar with the FCC rules and test procedures have reviewed the test setup, measured data and this report. I believe them to be true and accurate. The INVOCON, Inc. MicroWIS Sensor Unit was tested to and found to be in compliance with FCC Part 15 Subpart C for an Intentional Radiator. The highest emissions generated by the above equipment are listed below: Frequency (MHz)Level (dB μV/m)Limit (dBμV/m)Margin (dB) Fundamental916.583.693.9, 3m10.3 Spurious2749.833.749.5, 1m15.8 Occupied Bandwidth395 kHz ______________________________ Jeffrey A. Lenk President This report has been reviewed and accepted by INVOCON, Inc.. The undersigned is responsible for ensuring that the MicroWIS Sensor Unit will continue to comply with the FCC rules. ______________________________ Certificate of Compliance Professional Testing (EMI), Inc.Page 4 of 15 1.0EUT Description The Equipment Under Test (EUT) is the INVOCON, Inc. MicroWIS Sensor Unit. The MicroWIS Sensor Unit is a transceiver used to send digital representations of analog sensor signals to a remote data acquisition computer. The EUT functions as a transceiver sending data to remote MicroWIS PC Interface Units (PCIU) . The EUT operates at 916.5 MHz and is designed for compliance with 47 CFR 15.249 of the FCC rules. Specific test requirements for this device include the following: 47 CFR 15.249 Fundamental Transmit Power 47 CFR 15.249(c)/15.209Out of Band Emissions 47 CFR 15.203Antenna Requirement The system tested consisted of the following: Manufacturer & Model Serial #FCC ID #Description INVOCON, Inc. , MicroWIS Sensor Unit N/ANJM0071-027-028Data Acquisition Transceiver, 916.5 MHz 1.1EUT Operation The MicroWIS SensorUnit was made operational and placed on the test table. Normally it is interrogated by a host McroWIS PCIU usually installed in a Laptop PC which operated the remote transceiver. Setup and operational modes cover worst case configuration and operational modes for the device. The frequency of the transmitting signal is 916.5 MHz. 2.0Electromagnetic Emissions Testing Professional Testing (EMI), Inc. (PTI), follows the guidelines of NIST for all uncertainty calculations, estimates and expressions thereof for EMC testing. Radiated emission measurements were made of the Fundamental and Spurious Emission levels for the MicroWIS SensorUnit. Measurements of the occupied bandwidth were also made for the equipment. Measurements of the maximum emission lev…

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