Though we live in the digital age...
...our world is still analog
It’s common to equate measurements with data, but quantifying a measurand (e.g. temperature, pressure, acceleration) requires the transduction of a physical phenomenon into an electrical waveform. The generation and shaping of this analog waveform is called signal conditioning: if not done properly, the digital data obtained from it may not be accurate or even usable.
PFI has spent over 50 years developing best-in-class techniques to optimize the most critical components of a signal conditioning system. Some notable examples include:
Balanced Constant Current (BCC™) Excitation
Many sensors, such as strain gages and RTDs, require a source of electrical excitation to generate a signal. Signal conditioners provide this excitation, and PFI has developed best-in-class circuit designs to optimize the accuracy and reliability of variable-resistance sensor measurements. Prominent among these is the Balanced Constant Current technique, which provides numerous advantages over conventional voltage excitation of a Wheatstone bridge. Learn More..
REZCOMP® Resonance Compensation
Sensor resonance is a common problem for accelerometers, pressure sensors, and microphones. Large-amplitude resonance can swamp the signal of interest and cause distortion of the output waveform, effects that cannot be corrected once the waveform is sampled. PFI's patented REZCOMP technology, developed in collaboration with Kulite Semiconductor Products, compensates for the resonant response of sensors in real time prior to subsequent conditioning and A/D conversion. Learn More..
Precision Analog Filters
Analog filters are frequency selective electrical circuits that play a key role in any signal conditioning system. When properly designed they can faithfully preserve a sensor's output waveform and spectral content while eliminating unwanted noise components. Band-limiting the signal prior to sampling can allow for lower sampling rates by providing alias protection and remove out-of-band noise that can overload an A/D converter, corrupting the sampled data. PFI's programmable Flat and Pulse mode filters are optimized for frequency and time domain applications, respectively, outperforming conventional filter types across a range of response metrics. Learn More...
Distributed Gain
A primary function of a signal conditioner is the amplification of low-level signals to span the full dynamic range of a connected A/D converter. It is standard practice to apply the gain early in the signal chain to maximize the signal-to-noise ratio (SNR), but doing so before an analog filter is applied can result in saturation and overload due to out-of-band energy. To guard against this, PFI designs conditioners that distribute gain across both sides of the filter, thereby optimizing SNR while minimizing the risk of data corruption. Learn More...
A Case in Point
There may be no better example of a measurement application requiring high-performance analog signal conditioning than rocket engine testing. PFI has a long and distinguished track record supporting the aerospace industry's critical need for measurement systems capable of performing under the harshest of conditions during non-repeatable tests in which failure to collect valid data is not an option. Our instrumentation was deployed for testing of the RS-25 rocket engines that provide the main propulsion source for NASA's Space Launch System (SLS) – the same system that performed successfully during the recently completed Artemis II mission.
Single-engine hot fire test of the RS-25 engine at NASA Stennis Space Center (figure courtesy of NASA)