Channel Card Clock Synchronization Using GPS-Timed FPGA Mediation
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Solution Overview
Problem
Conventional mobile communication systems face challenges in synchronizing Digital Signal Processing (DSP) modems and system clocks within channel cards, leading to inconsistent data output timing between channel cards due to power on/off cycles and the inability of DSP hardware to receive and process system clocks directly.
Innovation Solution
A method and apparatus that utilize a Global Positioning System (GPS) timer to synchronize DSP modems and system clocks by sending a reference signal, recording GPS timer values, and adjusting start point information, allowing for synchronized data transmission between DSP and FPGA modems, and across multiple channel cards.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Adaptability or versatility
If a DSP modem operates with a local oscillator clock signal, then the DSP can process digital data independently, but the data output timing changes with each power on/off cycle and cannot be synchronized with the system clock
Solution Approach 1:
The system implements feedback by having the FPGA modem continuously monitor the actual data output timing from the DSP modem and compare it with the expected timing based on system clock. The FPGA then adjusts its processing to compensate for timing deviations, ensuring synchronized data output across multiple power cycles.
Solution Approach 2:
The FPGA modem acts as an intermediary between the DSP modem and the system clock. It receives data from the DSP, processes it with adjustable timing, and outputs synchronized data to the IF board. This intermediary layer allows the system to maintain both independent DSP operation and consistent timing synchronization.
2Ease of manufacture
If the DSP modem hardware cannot receive and process system clock directly, then the DSP operates with its own clock, but synchronization with the system is infeasible
Solution Approach 1:
The FPGA modem serves as an intermediary that receives both the DSP output and the system clock signal. It performs the synchronization function that the DSP hardware cannot perform, allowing the DSP to remain simple while achieving system-level synchronization through the FPGA's timing adjustment capabilities.
Solution Approach 2:
The system replaces the need for direct hardware-level clock interfacing in the DSP with a software/firmware-based timing adjustment mechanism in the FPGA. This substitution allows synchronization to be achieved through programmable logic rather than complex hardware modifications to the DSP.
3Adaptability or versatility
If each channel card uses its own local oscillator, then each card operates independently, but synchronization between multiple channel cards differs due to respective timing changes
Solution Approach 1:
The system merges the timing reference function at the FPGA modem level across all channel cards. By using a common system clock reference in the FPGA and implementing coordinated timing adjustment, multiple independently operating channel cards can produce synchronized data output when processed by the IF board.
Solution Approach 2:
The FPGA modem implements universal synchronization functionality that works across all channel cards regardless of their individual operating states. The FPGA's timing adjustment mechanism provides a common reference framework that enables consistent synchronization behavior across the entire system of multiple channel cards.
Data Source
AI summary
An apparatus and a method for synchronization in a channel card in a mobile communication system are provided. A channel card for synchronizing a Digital Signal Processing (DSP) modem and a system clock in a mobile communication system includes the DSP modem for sending a reference signal, informing of a start of a transmission, to a Field-Programmable Gate Array (FPGA) modem, and the FPGA modem for comparing a reception time of the reference signal with a Global Positioning System (GPS) timer, for recording a GPS timer value corresponding to a start point based on the comparison, and for sending to the DSP modem the recorded GPS timer value corresponding to the start point at a preset GPS timer reference time.