RF Test Instruments Using Virtual Triggers for Jitter-Free Time Stamping
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Solution Overview
Problem
Existing test and measurement devices for radio frequency signals suffer from reduced accuracy due to jitter in trigger signals, which is caused by imperfections in the finite steepness of trigger signal edges, leading to deviations in time stamping and overall signal processing precision.
Innovation Solution
A test and measurement instrument that uses a periodic external trigger signal to generate virtual trigger pulses with precise temporal spacing, compensating for jitter by determining the intended periodicity of the trigger pulses and generating virtual trigger pulses that exactly follow this periodicity, ensuring accurate signal processing.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a new individual trigger signal is generated for each burst of the repetitive radio frequency signal, then the measurement can be initiated for each burst, but the precision of triggering is reduced due to jitter caused by finite steepness of trigger signal edges
Solution Approach 1:
The patent applies preliminary action by pre-generating a large number of virtual trigger pulses with precisely defined temporal spacing before the actual measurement process. These virtual trigger pulses are created in advance based on the expected burst timing, eliminating the need to generate trigger signals on-the-fly for each burst. This preliminary preparation ensures that when bursts occur, the corresponding virtual trigger pulses are already available with exact temporal positioning, thereby resolving the jitter issue while maintaining the ability to trigger on each burst.
Solution Approach 2:
The patent uses the copying principle by creating virtual trigger pulses that replicate the timing pattern of expected bursts without being physically generated at the moment of each burst. Instead of generating unique trigger signals for each burst (which introduces jitter), the system copies the ideal temporal spacing pattern into multiple virtual trigger pulses stored in memory. These copies provide precise triggering references that eliminate jitter while maintaining the one-to-one correspondence between bursts and trigger events.
2Measurement precision
If trigger signals are refined to reduce jitter, then the precision of time stamping is improved, but the efforts and costs associated with refinement become high
Solution Approach 1:
The patent replaces the mechanical/physical approach of refining trigger signals (which involves complex circuitry and signal conditioning to reduce jitter) with a digital/software-based approach. Instead of physically refining trigger signals through hardware filtering and shaping, the system uses virtual trigger pulses generated and stored in digital memory with precisely defined temporal spacing. This substitution of mechanical signal refinement with digital timing control dramatically reduces device complexity and cost while achieving superior time stamping precision.
3Manufacturing precision
If virtual trigger pulses are generated based on detected periodicity, then the temporal spacing between virtual trigger pulses becomes exact, but the system must process the periodic external trigger signal to determine its periodicity
Solution Approach 1:
The patent applies universality by designing the trigger circuit to perform multiple functions: it detects the periodic external trigger signal, determines its periodicity through statistical evaluation, generates virtual trigger pulses with exact temporal spacing, and stores them in memory. This multi-functional trigger circuit eliminates the need for separate components for each function, reducing overall device complexity despite the sophisticated processing required. The same circuit that receives the external trigger signal also performs the statistical analysis and virtual pulse generation, making the system efficient and compact.
Data Source
AI summary
Embodiments of the present disclosure relate to a test and/or measurement instrument for measuring a radio frequency signal. The instrument has an input port, a measurement circuit configured to measure and digitize the radio frequency signal, thereby outputting a data stream. The instrument also has a trigger port configured to receive a periodic external trigger signal with periodically spaced trigger pulses. Further, the instrument has a trigger circuit configured to generate virtual trigger pulses based on the trigger pulses in the periodic external trigger signal. The instrument also includes an acquisition control circuit configured to receive the virtual trigger pulses. The acquisition control circuit is configured, upon reception of a virtual trigger pulse, to add a trigger information to the data stream generated by the measurement circuit.