# US 2019/0173597 A1 · Method and apparatus for tdma slot synchronization and calibration of master and slave

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- Number: US 2019/0173597 A1
- Document ID: US20190173597A1
- Status: Published application
- Kind: A1
- Application number: 16/080,568
- Filed: 2017-10-11
- Published: 2019-06-06
- Earliest claimed: 2017-06-14
- Assignees: Harxon Corporation
- Applicants: Harxon Corporation
- Inventors: Haijun Zhang; Guanghui Huang; Shiwei Wu; Jie Zhang
- Web page: https://patentgrep.com/patent/US20190173597A1

## CPC

- H04J 3/0644: {External master-clock}
- H04J 3/0647: {Synchronisation among TDM nodes}
- H04J 3/0655: {using timestamps}
- H04J 3/14: Monitoring arrangements {(for SDH/SONET rings H04J3/085)}
- H04W 56/0005: {synchronizing of arrival of multiple uplinks}
- H04W 56/004: {compensating for timing error of reception due to propagation delay}
- H04J: MULTIPLEX COMMUNICATION (transmission in general H04B; peculiar to transmission of digital information H04L5/00; systems for the simultaneous or sequential transmission of more than one television signal H04N7/08; in exchanges H04Q11/00; stereophonic systems H04S)
- H04W: WIRELESS COMMUNICATION NETWORKS (broadcast communication H04H; communication systems using wireless links for non-selective communication, e.g. wireless extensions H04M1/72)

## Abstract

The present disclosure relates to a method and an apparatus for TDMA slot synchronization and calibration of a master and a slave. The method includes: receiving a synchronizing frame from a master by at least one slave, in which the synchronizing frame includes a first count value of a timing counter of the master; analysing the synchronizing frame by the at least one slave to acquire the first count value; adjusting a TDMA slot of each slave according to the first count value and a second count value of a timing counter of the slave to synchronize the TDMA slot of the slave with a TDMA slot of the master. It can be seen that the synchronization is realized by directly using the respective clock sources of the master and the slave, without addition of the clock source of the RTC or the GPS module, thus reducing the cost and improving the accuracy.

## Claims

### Claim 1

A method for TDMA slot synchronization and calibration of a master and a slave, comprising:
receiving a synchronizing frame from a master by at least one slave, wherein the synchronizing frame includes a first count value of a timing counter of the master;
analysing the synchronizing frame by the at least one slave to acquire the first count value;
adjusting a TDMA slot of each slave according to the first count value and a second count value of a timing counter of the slave to synchronize the TDMA slot of the slave with a TDMA slot of the master.

### Claim 2 (depends on 1)

The method according to claim 1, wherein before receiving a synchronizing frame from a master by at least one slave, the method further comprises:
performing a frequency division on a clock source of each slave to determine a time granularity of the timing counter of the slave;
setting a third count value of a compare register of the slave.

### Claim 3 (depends on 1)

The method according to claim 1, wherein adjusting a TDMA slot of each slave according to the first count value and a second count value of a timing counter of the slave comprises:
keeping the second count value of the timing counter of the slave unchanged if a difference between the first count value and the second count value is zero;
delaying the second count value of the timing counter of the slave by a first number A of the time granularities and subsequently controlling the timing counter to restart counting if the first count value is greater than the second count value and the difference between the first count value and the second count value is the first number A;
subtracting a second number B from the third count value of the compare register of the slave to acquire a fourth count value and controlling the timing counter to restart counting when the second count value reaches the fourth count value if the first count value is smaller than the second count value and the difference between the first count value and the second count value is the second number B.

### Claim 4

A method for TDMA slot synchronization and calibration of a master and a slave, comprising:
acquiring a first count value of a timing counter by the master;
reading a third count value of a compare register by the master;
performing a preset interrupting program to generate a synchronizing frame and sending the synchronizing frame to at least one slave, and controlling the timing counter to restart counting, when the first count value is equal to the third count value.

### Claim 5 (depends on 4)

The method according to claim 4, wherein before acquiring a first count value of a timing counter by the master, the method further comprises:
performing a frequency division on a clock source of the master to determine a time granularity of the timing counter of the master;
setting the third count value of the compare register of the master.

### Claim 6

An apparatus for TDMA slot synchronization and calibration of a master and a slave, provided in each slave and comprising:
at least one processor;
at least one memory communicated with the at least one processor;
at least one module stored in the at least one memory and executable by the at least one processors, and comprising:
a receiving module configured to receive a synchronizing frame from a master, wherein the synchronizing frame includes a first count value of a timing counter of the master;
an analysing module configured to analyse the synchronizing frame by the slave to acquire the first count value;
an adjusting module configured to adjust a TDMA slot of the slave according to the first count value and a second count value of a timing counter of the slave to synchronize the TDMA slot of the slave with a TDMA slot of the master.

### Claim 7 (depends on 6)

The apparatus according to claim 6, further comprising:
a first determining module configured to perform a frequency division on a clock source of the slave to determine a time granularity of the timing counter of the slave;
a first setting module configured to set a third count value of a compare register of the slave.

### Claim 8 (depends on 6)

The apparatus according to claim 6, wherein the adjusting module comprises:
a first comparing unit configured to keep the second count value of the timing counter of the slave unchanged if a difference between the first count value and the second count value is zero;
a second comparing unit configured to delay the second count value of the timing counter of the slave by a first number A of the time granularities and subsequently control the timing counter to restart counting if the first count value is greater than the second count value and the difference between the first count value and the second count value is the first number A;
a third comparing unit configured to subtract a second number B from the third count value of the compare register of the slave to acquire a fourth count value and control the timing counter to restart counting when the second count value reaches the fourth count value if the first count value is smaller than the second count value and the difference between the first count value and the second count value is the second number B.

### Claim at position 9

9-16. (canceled)