28608B Quad Programmable
Filter/Amplifier
The 28608B Octal Programmable Filter/Amplifier Card is ideal for conditioning low-level voltage inputs in front of high-resolution digital data acquisition systems. Low-pass, high-pass and band-pass configurations are available.
The 28608B allows for up to 128 channels of programmable precision filtering in one 28016B-M3 chassis.
A choice of 4 or 8-pole low-pass filters, 4-pole high-pass and 8-pole band-pass filters are available. Cutoff settings from 1 Hz to 204.6 kHz are supported. The low-pass filters may operate in either a "flat" mode for maximally flat pass-band amplitude response with sharp roll-off or in a "pulse" mode for low phase distortion and optimized transient response.
The "flat" mode provides pass-band characteristics nearly identical to a Butterworth filter while providing a much sharper roll-off. This mode is a good choice for applications such as spectral analysis. The "pulse" mode has time domain response similar to the Bessel filter yet provides superior amplitude response characteristics. The "pulse" mode is ideal for time domain applications including transient (shock) measurements and time domain waveform analysis.
Programmable pre- and post-filter amplifiers provide an overall gain of 8192. Gain is distributed both before and after the filter to provide protection from large out-of-band energy or transients that could cause clipping before the filter, distorting the data. The post-filter gain has resolution of better than 0.05% to enable system scaling of the outputs to match the full-scale input of the external recording device. Overload detectors alert the user to over-voltage conditions. Precise, automated digital calibration of gain and DC offset are provided.
Other features of the 28608B include a test input for injection of calibration signals into the channel input and a monitor output that allows for convenient monitoring of any channel output via a single BNC on the 28000 chassis.
Applications Examples
- Anti-Aliasing Filters with Programmable Amplifiers
- Automatic Test Equipment
- Data Acquisition
- Signal Conditioning
- Production Test Equipment
- Industrial Process Control
- Reconstruction Filters
- Programmable Band-Pass Filters
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SALIENT FEATURES
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Number of Channels: |
8 channels per card;
128 channels per chassis |
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Inputs: |
Balanced differential with programmable AC/DC coupling |
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Zero Suppress: |
Programmable DC voltage is inserted at channel input |
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Pre-Filter Gain: |
x1 to x512 in x2 steps with input overload detection |
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Post-Filter Gain: |
x0.25 to x16 with 0.05% resolution |
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Filters: |
Choice of 4- or 8-pole low-pass filters
or 8-pole band-pass filters |
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Cutoff Frequency: |
Pulse Mode Programmable from 1 Hz to 102.3 kHz; Flat Mode programmable from 2 Hz to 204.6 kHz; and wide-band (500 kHz) |
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Outputs: |
DC coupled, single-ended with ground sense. Two additional buffered outputs per channel supported by option front panel plug-in adapters. |
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Test Support: |
Test input and monitor output busses |
28608B Channel Diagram
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Optional Output Adapters
Measurement systems sometimes require multiple outputs per signal conditioning channel. These outputs may be routed to control systems, tape backup systems, auxiliary data acquisition systems, scope bays and other destinations.
28608B cards are fitted with front panel connectors that accept the output adapter modules. Adapters plug on to the front of the signal conditioner card and are secured to the card by two screws. The adapters provide two additional fully buffered outputs per channel on two high-density 26-pin D shell connectors.
Download 28608B Octal Programmable Filter Amplifier Specification Sheet form the PF Publications Library.
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