Wireless Link - 500e Digital Telemetry Systems

SR-500e Receive System - ST-500e Digital Telemetry Transmit System

By applying the latest digital signal processing technology, the ST-500e Digital Telemetry Transmit System, combined with the companion SR-500e Receive System, offers a versatile and cost effective solution to telemetry applications ranging from turbines, generators, kilns, car engines and other hard-to-get-at places. Furthermore, the price of these products offers effective alternative solutions to simple applications, such as transferring analog signals across a city street. A single general purpose design allows this unique system to be applied to a wide variety of sensor configurations, including multiple and mixed inputs of thermocouple data, strain bridges and various other types of static or dynamic input voltages. The digital architecture of the implementation not only insures the integrity of the data measurements throughout the detection, transmission, recovery and output processes, but also allows the system to automatically compensate for steady state or dynamic errors introduced by external or internal sources.

SRI PMD offers standard and custom analysis software packages compatible with execution on most standard Personal Computers (PCs). The software utilizes standard interfaces to communicate with the SR-500e Receive System, frequently eliminating the need for stand-alone data recorders, strip charts and/or oscilloscopes. By providing data storage and retrieval functions, operators may capture critical measurement data, alter operational parameters of a system under test and then perform detailed comparison and analysis on new measurements.

ST-500e Transmitter

The ST-500e Transmitter is usually encapsulated within thermally conductive epoxy, allowing it to be installed in locations presenting severe environmental and/or contaminated conditions.

The heart of the ST-500e Transmitter is a powerful and versatile micro-controller (MCU) capable of up

to 30 million operations per second. Firmware loaded into the MCU at the factory supports a wide variety of sensor types to satisfy most common applications and permits software programming of sensor gains and offsets. The miniaturized 2" x 1.5" x 0.8" form factor and <2.5 oz weight allows the Transmitter to be used in applications where typical telemetry transmitters are not possible.

Tables loaded within electronically erasable PROM (EEPROM) memory space establish the sensor configuration of each transmitter. Referring to these tables, the controller invokes configuration settings for the analog sensor interface circuitry, altering the various input offset and gain parameters in order to accurately detect the input voltages. Up to eight (8) sensor inputs can be configured for a standard single ST-500e Transmitter. Units also acommodate up to 4 0-5VDC Analog and 3 TTL inputs. Custom input configurations are available for unique applications.

The EEPROM tables also control the operational parameters associated with sampling frequency for each sensor input. These settings directly affect the system transmission rate, allowing users to easily trade off transmission distance and noise immunity with sensor sampling rates. Sensor channels can also be selectively deactivated to increase the sampling rates for more critical measurements, adding to the flexibility of the unit. Setup is simple with default configuration values for most common sensor types and comprehensive gain, offset, and digital filtering adjustment capability.

An on-board temperature sensor combined with primary power voltage detection logic allows the design to compensate for measurement errors associated with temperature or voltage drifts. For most applications, the ST-500e can provide better than ±0.5% accuracy of most typical measurements can can support in excess of ±0.1% accuracy for extremely critical measurement requirements.

Primary power input for the design is largely dictated by the user’s application. At typical power consumption levels of under 35 mA, either 9 or 3V battery power can frequently satisfy limited time frame measurement functions. On a custom basis, PMD can develop special transmit power capabilities including rechargeable batteries of even inductively supplied power options.

The SR-500e requires a standard 12 Volt direct current (DC) power input. This enables the system to be utilized in mobile applications operating from standard automobile battery power. The system is also shipped with an AC to DC power adapter, enabling it to be connected directly to standard AC power outlets.

The SR-500e Receive System also employs advanced technology digital signal processing in order to recover the transmitted bit-stream from the wireless link, synchronize the date for frame detection purposes, and demultiplex the telemetry data

samples to the corresponding sensor channel. Both analog and digital sample outputs are provided on a per channel basis and an optional data capture and display package may be installed on a PC for applications requiring these capabilities.

In its standard mode of operation, the receive process automatically scans the input frequency spectrum and detects the selected ST-500e transmit waveform. This eliminates the need for tedious and cumbersome manual tuning of the FSK demodulator. Override control of this process sis also supported which, when combined with a built-in signal strength detection meter, allows an operator to assess the potential transmit spectrum and establish an optimum frequency for the particular application of the system.

Once valid signal recovery has been achieved, the logic automatically detects the sensor configuration and operational sampling parameters of the transmitter and processes the telemetry data accordingly to produce the channelized output waveforms. Configurable sample filtering may also be performed on a per-channel basis to eliminate noise corruption which may be present due to the operational environment.

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Specifications: PDF / Operations and Maintenance

General Specifications

Sensor Inputs: Up to 8 Selectable and/or Mixed
                 Sensor Differential: to ±45mVDC
                 Analog Differential: to ±2.5mVDC
                 Analog Single-Ended: 0-5VDC
                 (Analog Inputs Require High Impedance)
Channel S1-S8: Sensor
Channel A1-A4: Sensor, Diff & Single-Ended Analog
Channel T1-T3: TTL
Sample Rates: Up to 17ksps (8 bit mode)
                             9.5ksps (12 bit mode)
                             8.5ksps (16 bit mode)
Sample Res: Selectable between 8, 12 or 16 bit
Accuracy: ±0.5 % Typical Measurement Acc.
                  ±0.1% Obtainable
Frequency Response: Up to 8KHz+ steady state
Radio Frequency: Unlicensed ISM, select
                  915, 868, or 433 MHz Bands
RF Output: 0 to +11dBm, RP-SMA Female
Range: Up to 500 feet
Modulation: FSK
Primary Power: <50mA at 5 VDC
Operating Temp: 0° to +85°C
                               -30° to +85°C Optional

Typical Instruments Supported

Temperature: Type J or K Thermocouples
                          0 to +1000°C
Strain Gauge: 1, 2 or 4 Arm Bridge, 120/350 Ohm
                         up to 5 VDC Excitation Provided
                         Millistrain Resolution
Generic Voltages:
                         Static or Dynamic
                         Differential or Single Ended
                         Unipolar or Bipolar
                         Selectable from 2 mV to 5 V Range
                         High Impedance Input Required
Other Typical Sensors:
                         Pressure Transducers
                         Accelerometers
                          Displacement Gauges
                         Weather Sensors
                         Custom

General Specifications

Supports: Up to 8 Defined Transmitters
Acquisition: Automatic
Status Indicators: Signal Lock/Data Error Detect
Analog Outputs: Up to 8 selectable for 0-5,
      0-10, ±5, ±10 VDC
Digital Outputs: 12 Bits Measurement Data
      plus Channel, Strobe, Error Ind.
Data Processing: Compensation (Temp
      Dependent), Filtering, Averaging
Packaging: Desktop Enclosure
Operating Temp: 0° to 70 °C

Remote Interface

Specifications: RS-232, DTE, up to 115 kbps
                           USB
Functions: Standard Status/Control
                    Firmware Upgrade
                    Real-time Data Transfer
                    Sensor Reconfiguration
                    Measurement Calibration

All specifications subject to change without notice or obligation to retrofit