Skip to main content
U.S. flag

An official website of the United States government

Official websites use .gov
A .gov website belongs to an official government organization in the United States.

Secure .gov websites use HTTPS
A lock ( ) or https:// means you’ve safely connected to the .gov website. Share sensitive information only on official, secure websites.

SBIR Success Story - Symmetricom

4775 Walnut Street, Ste 1B
Boulder, CO 80301

Contact: Samuel R Stein
Phone: 303-539-4904
Web Site

Project Title:  Direct-Digital Phase-and-Amplitude-Noise Measurement System

NIST Award(s):  SB1341-03-W-0817, SB1341-04-C-0022

Technology Developed: We developed a method to measure precise phase differences between a device under test and a reference based on purely digital phase detection. The two sources are first converted to digital samples. Phase detection is subsequently performed digitally and the resulting time series is analyzed to characterize the device under test.

Key Words: phase noise, phase measurement, phase spectrum, Allan deviation, Allan variance, DSP, short-term stability

Uses of Technology/Products/Service: The method enables a phase noise measurement instrument with improved ease of use, accuracy, and convenience. All one has to do is connect the device under test and an optional reference and press a single usa-button. For the first time, one instrument can make both phase noise and Allan deviation measurements. Another first is the capability to make phase noise measurements using a reference whose frequency is different from the device under test. This technology also makes it possible to make accurate measurements without calibrating the phase sensitivity of the phase detector as a function of frequency.

Benefit to Company: We had identified the direct method as a possible approach to phase noise measurement but had rejected it as too risky. This NIST phase 1 SBIR provided partial support to evaluate the performance of this new technology and lowered the risk. The NIST phase 2 SBIR provided partial support of the first production instrument and validation of its performance. The SBIR process resulted in the introduction of a standard commercial product. See

Our phase noise measurement product is already recognized as the easiest and most accurate method of making phase noise measurements for devices under 30 MHz and the highest performance Allan deviation test set. 

Impact on Company Growth: Tactical, Strategic

How Product Was Commercialized: The commercialization process was started between phase 1 and phase 2. The hardware problems were solved before phase 2 and the firmware and software were completed during phase 2. We delivered one of the first production units to NIST at the end of phase 2 and received very useful feedback as well as evaluation from NIST. The models 5115A and 5120A shown on our web site at

resulted from the NIST SBIR.

Other Comments Related to Company's Success Story: The time between the award of phase 1 and the delivery of the first production unit was extremely short (approximately 18 months). There are applications of the technology to other product that we intend to pursue.

Created March 6, 2012, Updated August 23, 2023