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I N T E R F A C E M O D U L E
L-3 Telemetry & RF Products’ (L-3 T&RF) NCC-2916 is a signal conditioning module that monitors up to 16 analog inputs from accelerometers that require constant current excitation, generating converted digital output in 16 unique measurements.
The module design utilizes specialized
Digital Signal Processing (DSP) filtering concepts that provide performance similar to traditional analog-based implementations, while requiring significantly fewer electronic components. The end result is greater channel density, at a lower cost per channel, with greater functionality.
Each channel provides an input multiplexer used to select between the external transducer input and multiple internal calibration sources. The multiplexer’s output is fed to a programmable gain stage that supports a gain between 1 and 128. The amplified signal is then passed through an anti-aliasing filter, followed by an Analog-to-Digital Converter (ADC) operating at a rate of 390.625 ksps and feeding the DSP filter. To minimize distortion (≤ 72 dB) induced by frame sampling, the data is up-sampled from 390.625 kHz to 50 MHz.
The NCC-2916 features a constant current excitation source that provides fixed 3.5 mA per channel. Each channel provides a number of calibration and balance features to facilitate programming and checkout including Zero
Calibration (Z-CAL), Substitution Calibration (N-CAL), Voltage Calibration
(V-CAL) and amplifier/ amplifier offset.
• 16 channels of analog signal conditioning for devices (two-terminal
Integrated Electronic Piezoelectric
(IEPE) Accelerometers) that require constant current excitation
• Each channel has independent and user-selectable gain and offset settings
• Programmable settings allow for total gain from 1 up to 128
• Each channel supports inputs up to
10Vp-p. Examples of such devices include the PCB Group ICP line of sensors and Endevco’s Isotron line of sensors.
• Module supports Z-CAL, N-CAL,
V-CAL, amplifier offset and manual offset
• Supports simultaneous sample and hold function on a per-channel basis
• Provides constant current excitation source at 3.5 mA per channel
• Fully programmable by L-3’s
Vista TEC™ software

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I N T E R F A C E M O D U L E
The NCC-2916 allows the user to enable simultaneous sample and hold mode, which provides phase correlation between all similarly configured analog channels within the entire Data Acquisition Unit (DAU), or within a complete synchronized NetDAS™ system.
All features of the NCC-2916 are supported by L-3’s Vista TEC™ software, which includes an operational checkout feature that provides automated testing of all channels to compare data received and against user specified targets.
INPUT
Device Compatibility
Full Scale (FS) Range
IEPE Accelerometer; +Terminal accepts constant current excitation while also outputting a voltage signal proportional to the acceleration being sensed.
10 Vp-p / gain
Input Impedance 10 MΩ nominal
Over-Voltage Protection ± 40 V with latch-up protection
Single-ended thru (1-pole) 3 dB cutof f at 1.6 Hz high-pass
RC filter
GAIN
Selectable Gain
Accuracy
Stability
Programmable gain from 1 to 128, gain of 1 is 10 Vp-p
± 0.5 %
± 0.75 % of selected value, including effects of excitation drift
Linearity
OFFSET
± 0.1 % Best Straight Line (BSL)
Channel Offset Stability ± 0.5 % FS over temperature
Reference to Output (RTO) ± 50 % of FS range=
Offset Capability (offset performed in Field-Programmable Gate Array
(FPGA) before filtering)
Output / Channel Offset ± 0.5 % FS over
Stability temperature
DIGITAL FILTER
Programmable 3 dB
Cutoff Frequency (Fc)
FC = 10 Hz to 8.014 kHz
Spacing of selectable cutoffs, 12%
FC
Full Passband (FPB) FPB = 0.6144 x FC (defined as
6.144 Hz to 4.923 kHz)
Inter-Channel Correlation ± 2 degrees, DC to Passband
(between channels configured for the same FC)
Stopband
Amplitude Response
> 2.5 x FC @ 40 dB minimum
Flat within ± 0.5 % from DC to FPB for FC < 5 kHz + 0.5 % / -1% for FC
> 5 kHz -3 ± ½ dB at FC
Filter Type 6-pole, low-pass Butter worth
Infinite Impulse Response (IIR) filter
Output Rate
ADC Sample Rate
50 Msps
50 MHz / 128 = 390.625 ksps
EXCITATION
Number of Excitation
Supplies
Range
Accuracy
16
Factory fixed at 3.5 mA
Guaranteed 2 to 10 mA over all conditions with compliance of 24 V
OUTPUT
16-Bit Conversion The channel output is converted to a 16-bit word, either straight binary or 2s complement
Note: Full-scale signal is converted into 15 bits, with remaining bit used to accommodate offset
Supports either common word size or extended read mode.
Status: unique measurements that contain current balance status.
L-3 Telemetry & RF Products
9020 Balboa Avenue
San Diego, CA 92123
1515 Grundy’s Lane
Bristol, PA 19007
Tel: 858.694.7500
800.351.8483
Tel: 267.545.7000
Email: Sales.TRF@L-3com.com
L-3com.com/TRF
This presentation consists of L-3 Communications Corporation general capabilities information that does not contain controlled technical data as defined within the
International Traffic in Arms (ITAR) Part 120.10 or Export Administration Regulations (EAR) Part 734.7-11 Data, including specifications, contained within this document are summary in nature and subject to change at any time without notice at L-3’s discretion. Call for latest revision. All brand names and product names referenced are trademarks, registered trademarks, or trade names of their respective holders.
BRML683 Rev A