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FAS100 Frequency Acquisition Systems


The FAS100 is a modular, multi-channel frequency acquisition system, designed with scalability and high production volumes in mind. 

 Ordering Information/Printable Copy

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Key Features

  • Simultaneous frequency acquisition across many channels: the FAS100 allows for simultaneous frequency measurements across multiple channels. This is a standout feature compared to systems that use RF switching or power cycling, which can affect frequency accuracy and stability. This also dramatically improves system efficiency, which is crucial in high-volume environments.
  • Zero dead time readings: Continuous data capture without interruptions, essential for certain types of evaluation, such as Allan Deviation.
  • Adjustable Gate Times: Obtain readings at any desired gate time between 10 milliseconds and 24 hours. 
  • High channel-to-channel isolation: Minimal crosstalk, ensuring more accurate and reliable data.
  • Independent counter per channel: Each channel in the FAS100 has its own dedicated frequency counter.
  • Daisy-chainable up to thousands of channels: The FAS100 was designed with production-level scalability in mind, allowing for modular upgrades.
  • Bandwidth up to 100 MHz: Obtain data on a wide bandwidth of frequency sources, up to 100 Megahertz.
  • DB25 digital I/O expansion port: Offers versatile connectivity for easy integration with external devices and systems, enhancing control and expandability options.


  • Frequency acquisition for the characterization of system-level timebases such as: XOs, VCXOs, TCXOs, OCXOs, and Rubidium Frequency Standards
  • Enables qualification of system clocks for timing applications including: GPS, Radar, Radios, Guided Munitions, SATCOM, Cellular Infrastructure, Stratum-Compliant Devices, SARSAT, Test Instrumentation, etc.
  • Ideal for oscillator manufacturers to test frequency-based parameters at production volumes


Functional Description

The FAS100 utilizes one or more FMS100-32 modules to perform parallel frequency measurements simultaneously and continuously. System power and data transmission are managed by an SPS400 module (master controller). Each SPS400 can manage up to four FMS100-32s. Multiple SPS400/FMS100-32 configurations can be daisy-chained for a substantial increase in overall system size.

The FMS module uses 32 independent reciprocal counters operating at 80MHz giving a native resolution of 12.5ppB per second. To increase measurement resolution and isolation, the module down-converts the inputs to provide an intermediate frequency (I.F.) to the counters. This method improves the resolution by the down-conversion factor.

The FMS100-32 contains a buffer that can temporarily store 128-1024 measurements per channel (depending on configuration) until retrieved by the PC. For aging systems that typically use 1-hour gate times, this is more than 5 days of readings. For short gate times, the PC must retrieve the measurements before the buffer fills, or measurements will be overwritten.

Each sequential group of four channels can be configured with a different gate time if desired. For example, in an aging system you might use 1-hour gate times for most units, but may want more data for experimental units, so you could configure those channels to take readings at a shorter gate time.

Example Configuration:

256-Channel TCXO Aging Systems:


Custom Fixturing:

64-Channel TCXO Test Card:


8-Channel OCXO Test Card:


 Production System Examples: