Distributed Radio System Serial Clock Data Interface
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Solution Overview
Problem
In car radio systems, the multipath reception phenomenon due to signal reflections reduces radio receiver performance, and existing phase diversity algorithms are limited by small frequency offsets from different crystals, making it impractical to separate FM receiver tuners by more than a quarter wavelength, which is incompatible with distributed systems using long digital cables that introduce interference.
Innovation Solution
A serial data interface using a wideband noise-like serial data signal with a clock/data recovery circuit and a phase diversity circuit to combine signals, eliminating the need for separate reference clock lines and allowing standard twisted-pair cables, minimizing interference and maintaining phase diversity performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If separate crystal oscillators are used in each antenna path, then each receiver can operate independently, but frequency offsets between crystals cause continuously changing phase that cannot be distinguished from time of arrival differences, limiting the practical distance between receivers
Solution Approach 1:
The patent merges the clock reference function into the data transmission itself by encoding clock information within the serial data stream. This allows both receivers to synchronize to the same clock reference carried in the data, eliminating the need for separate crystal oscillators while maintaining independent operation. The clock and data are combined in a single transmission channel.
Solution Approach 2:
The serial data interface acts as an intermediary that carries both data and clock information between receivers. Instead of using separate crystal oscillators that create frequency offsets, the intermediary data stream provides a common timing reference that both receivers can lock onto, eliminating phase drift while allowing physical separation.
2Length of moving object
If long digital cables are used to connect distributed receivers, then physical separation for uncorrelated signal reception is achieved, but cable interference degrades signal quality and introduces noise
Solution Approach 1:
The patent replaces the mechanical/electrical connection method (separate clock lines and data lines) with a digital serial communication system. By encoding all information including clock references in a serial data stream, the system can use standard twisted-pair cables instead of sensitive RF connections, significantly reducing interference and noise while allowing longer cable lengths.
Solution Approach 2:
The clock signal is effectively copied and embedded within the data stream itself. Instead of transmitting a separate physical clock signal that is vulnerable to interference, the timing information is copied into the digital data format, which is inherently more robust to cable interference and can be recovered cleanly even over long distances.
3Measurement precision
If separate reference clock lines are used to synchronize receivers, then phase diversity can be maintained, but system complexity increases and cost increases due to additional components and wiring
Solution Approach 1:
The patent combines the clock signal and data signal into a single serial transmission channel. Instead of requiring separate physical connections for clock synchronization and data transfer, both functions are merged into one interface, dramatically reducing the number of components and wiring while maintaining precise phase alignment through the embedded clock reference.
Solution Approach 2:
The serial data interface serves multiple functions simultaneously: it transmits data, carries the clock reference, provides synchronization, and enables bidirectional communication. This multi-functional approach eliminates the need for dedicated clock lines and reduces overall system complexity while maintaining the precision required for phase diversity operation.
Data Source
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AI summary
A radio receiver including: a serial data interface configured to receive a serial data signal from another radio receiver; a clock /data recovery circuit configured to produce a clock signal and a data signal from the serial data signal; and a radio front-end configured to receive the clock signal from the clock/data recovery circuit to produce a received signal; and signal combining circuit configured to combine the received signal and the data signal.