The LX721 provides precision waveform and spectral analysis for a wide variety of applications and measurements. Various high resolution distortion measurements can be performed, as well as very broad band frequency domain and time domain amplitude measurements.

The LX721 provides a multi-function input capable of self-powering a wide variety of different types of transducers and sensors: microphone, acclerometer, magnetic, photo, pressure, hydrophone, etc. In most cases this eliminates the need for external preamps and/or power supplies.

A discrete input front end is utilized to provide extremely low voltage and current noise, along with extended input signal attenuation and gain ranging.

Features
• Ultra High Resolution Spectral Analysis
• Measurements: Amp,Dist,Spec,Decay,etc
• ADC Resolution 32 Bit
• Maximum Sample Length 4M
• High Frequency Bandwidth 200kHz
• Low Frequency Bandwidth DC,AC 0.5Hz
• Frequency Resolution 0.01Hz
• Multiple Sampling Rates
• Large Dynamic Range
• Very Low Distortion
• Input Modes: Bal,Unbal,ICP,PHM,DVP
• Input Impedance: 100K
• Stopband Attenuation 140dB
• Isolated/Floating Common
• 8 LED Indicators
• Interface: XLR, BNC, Banana Jacks

Multiple high resolution multibit delta-sigma modulators are combined through custom multirate filters and decimated to a 32 bit word size, at the desired sampling rate. Multiple sampling rates are provided. Data is transferred synchronously between memory and the digital signal conversion circuitry without interference. Sample data can be read/written to the controller host or PC asynchronously without affecting sampling timing or accuracy.

The LX721 front end utilizes a patented floating high voltage current limiter to handle overvoltage conditions in any gain range. The device appears as an ultra linear 25 Ohm resistor with unmeasureable distortion under normal signal conditions. During overload, the transition impedance device changes to a 200uA current source limiting current up to 500V blocking. The device presents a minimal noise density of only 0.65nV/RtHz.

The first input stage or front end of any spectrum analyzer is one of the most critical stages. While most other analyzers utilize monolithic commercial opamps, the LX721 employs a discrete opamp, the LA717. This discrete opamp contains over 80 components in less than 1 sq Inch. Many monolithic opamps have low voltage noise but have high current noise. The LA717 features both extremely low voltage, current, and flicker noise by using super high transconductance JFETs. The LA717 noise voltage is 0.95nV/RtHz and current noise is less than 0.08pA/RtHz. This results in up to 8dB noise improvement over monolithic opamp front ends through the front end 100K attenuator. The LA717 features computer matched JFETs, 30V/uS slew rate, 50MHz gain bandwidth product, 97dB loop gain, 75mA output current, and ±16mA supply current.

To handle both large and small input signal levels, the LX721 provides both attenuation and gain ranging. A 100K impedance balanced attenuator is used with -6.02dB step size and maximum attentuation of -30.1dB. Maximum gain is +24.08dB. This enables full scale input signal range levels from 240VRMS down to 470mVRMS. Combined with the 125dB dynamic range of the conversion processing, the total dynamic range spanned by the LX721 approaches 180dB.

Each module contains a 32 bit softcore embedded controlled operating at 100MHz synthesized from FPGA logic. The controller is responsible for managing all LXBUS data and command communications, Flash memory, PSRAM sample memory, and module control functions. The firmware can be updated in the field through the LX700 mainframe controller.

All sample data is stored locally within the module using multiple memory banks of PSRAM. The memory is dual ported allowing the computer interface to download data asynchronously without affecting the synchronous performance and timing accuracy of the internal digital stream.