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National Instruments 781214-01 RF Power Sensor

The National Instruments 781214-01 RF Power Sensor is designed for accurate RF power measurements across a wide frequency range of 10 MHz to 18 GHz. It is also known as the USB-5681. It is ideal for applications involving continuous wave, multitone and digitally modulated signals. It provides reliable average power readings over a dynamic range of 60 dB. The sensor supports input power ranges from -40 dBm to +20 dBm. Its dual-path architecture ensures accurate RMS measurements across the entire frequency and dynamic range.

The 781214-01 sensor includes advanced features such as auto averaging and repeat averaging. With a typical sample rate of 140 kS/s, it captures data at high resolution. The configurable aperture time from 0.01 ms to 300 ms provides flexibility in measurement timing while the duty cycle correction feature is useful for pulse modulated signal analysis. These features help ensure precision in power measurements whether for continuous or pulsed signals.

The NI 781214-01 model offers robust triggering options with both internal and external trigger capabilities. Internal trigger levels range from - 20 dBm to + 20 dBm with typical accuracy of ± 0.5 dB. External triggers operate with TTL/CMOS signals that provide flexibility in how measurements are initiated. The sensor’s trigger delay and noise immunity features ensure accurate and stable measurements even in challenging environments. Its time slot and scope measurement modes enable detailed signal analysis capturing up to 1,024 data points or 128 time slots.

The power sensor's calibration and correction data are stored onboard that eliminates the need for frequent external calibration. This allows for faster setup and more reliable measurements without the need for manual recalibration. The sensor's typical uncertainty in linearity is less than 3 %. Temperature compensation ensures accuracy under varying conditions with a compensation rate of less than 1.4 % across the operating temperature range of 0 °C to 50 °C.

The 781214-01 sensor is compact and lightweight. It measures 25 mm × 45 mm × 110 mm and weighs only 230 grams. It operates within a broad environmental range with a maximum altitude of 4,600 m and tested shock and vibration resistance in line with MIL-PRF-28800F standards.