# US 11,444,703 B2 · System for generating accurate reference signals for time-of-arrival based time synchronization

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- Number: US 11,444,703 B2
- Document ID: US11444703B2
- Status: Granted
- Kind: B2
- Application number: 17/129,682
- Filed: 2020-12-21
- Published: 2021-04-15
- Granted: 2022-09-13
- Earliest claimed: 2018-12-18
- Assignees: ZaiNar, Inc.
- Applicants: ZaiNar, Inc.
- Inventors: Philip Kratz; Mainak Chowdhury
- Web page: https://patentgrep.com/patent/US11444703B2

## CPC

- H04B 17/104: {of other parameters, e.g. DC offset, delay or propagation times}
- H04L 5/1461: {Suppression of signals in the return path, i.e. bidirectional control circuits}
- C07C 41/01: Preparation of ethers
- C07G 1/00: Low-molecular-weight derivatives of lignin (high-molecular-weight derivatives of lignin {C08H6/00})
- C08B 37/0057: {beta-D-Xylans, i.e. xylosaccharide, e.g. arabinoxylan, arabinofuronan, pentosans; (beta-1,3)(beta-1,4)-D-Xylans, e.g. rhodymenans; Hemicellulose; Derivatives thereof}
- C08H 6/00: {Macromolecular compounds derived from lignin, e.g. tannins, humic acids}
- D21C 11/0007: {Recovery of by-products, i.e. compounds other than those necessary for pulping, for multiple uses or not otherwise provided for (volatile compounds obtained by decomposition of spent liquors in order to regenerate them D21C11/125; compounds obtained by fractionating the liquors in order to regenerate them D21C11/0042)}
- H04B 1/16: Circuits
- H04B 1/40: Circuits
- H04B 17/0085: {using test signal generators}
- H04B 17/14: of the whole transmission and reception path, e.g. self-test loop-back
- H04L 5/0048: {Allocation of pilot signals, i.e. of signals known to the receiver (allocation of control signalling H04L5/0053; use of control signalling H04L5/0091)}
- H04L 7/0079: {Receiver details}
- H04J 3/0667: {Bidirectional timestamps, e.g. NTP or PTP for compensation of clock drift and for compensation of propagation delays (arrangements for monitoring round trip delays in packet switching networks H04L43/0864)}
- H04B: TRANSMISSION
- H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M)
- C07C: ACYCLIC OR CARBOCYCLIC COMPOUNDS
- C07G: COMPOUNDS OF UNKNOWN CONSTITUTION (sulfonated fats, oils or waxes of undetermined constitution C07C309/62)
- C08B: POLYSACCHARIDES; DERIVATIVES THEREOF (polysaccharides containing less than six saccharide radicals attached to each other by glycosidic linkages C07H; fermentation or enzyme-using processes C12P19/00; sugar industry C13; production of cellulose D21)
- C08H: DERIVATIVES OF NATURAL MACROMOLECULAR COMPOUNDS (polysaccharides C08B; natural rubber C08C; natural resins or their derivatives C09F; bituminous materials C10)
- D21C: PRODUCTION OF CELLULOSE BY REMOVING NON-CELLULOSE SUBSTANCES FROM CELLULOSE-CONTAINING MATERIALS; REGENERATION OF PULPING LIQUORS; APPARATUS THEREFOR
- 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)

## Abstract

A system for generating a self-receive signal includes: a signal generator; a first signal processor; a second signal processor; and an antenna. The system also includes a first passive coupling device: defining a first input port electromagnetically coupled to the signal generator; defining a first transmitted port; defining a first coupled port electromagnetically coupled to the first signal processor; and characterized by a first phase balance between the first transmitted port and the first coupled port. The system further includes a second passive coupling device: defining a second input port electromagnetically coupled to the antenna; defining a second transmitted port electromagnetically coupled to the first transmitted port; defining a second coupled port electromagnetically coupled to the second signal processor; and characterized by a second phase balance between the second transmitted port and the second coupled port substantially similar to the first phase balance.

## Claims

### Claim 1

A system for generating a self-receive signal comprising:
a signal generator;
a first signal processor;
a second signal processor;
a first passive coupling device;
a second passive coupling device;
an antenna;
a transmit chain:
electromagnetically coupling the signal generator to the antenna; and
configured to couple a transmitted signal from the signal generator for transmission at the antenna;
a self-receive chain:
electromagnetically coupling the signal generator to the first signal processor via the first passive coupling device; and
configured to back-couple the transmitted signal from the signal generator for reception at the first signal processor as a self-receive signal characterized by a first phase delay; and
a receive chain:
electromagnetically coupling the antenna to the second signal processor via the second passive coupling device; and
configured to couple a received signal at the antenna for reception at the second signal processor, the received signal characterized by a second phase delay.

### Claim 2 (depends on 1)

The system of claim 1, further comprising the receive chain configured to couple the receive signal from the antenna for reception at the second signal processor, the receive signal effected by the second phase delay substantially similar to the first phase delay.

### Claim 3 (depends on 2)

The system of claim 2, further comprising a digital controller electromagnetically coupled to a multiplexer and configured to:
select a self-receive signal port of the multiplexer during a transmit slot in a time-division multiple access frame; and
select a receive signal port of the multiplexer during a receive slot in the time-division multiple access frame.

### Claim 4 (depends on 1)

The system of claim 1, further comprising the first passive coupling device:
comprising a first input port electromagnetically coupled to the signal generator;
comprising a first transmitted port;
comprising a first coupled port electromagnetically coupled to the first signal processor; and
characterized by a first phase balance between the first transmitted port and the first coupled port.

### Claim 5 (depends on 4)

The system of claim 4, further comprising the second passive coupling device:
comprising a second input port electromagnetically coupled to the antenna;
comprising a second transmitted port electromagnetically coupled to the first transmitted port;
comprising a second coupled port electromagnetically coupled to the second signal processor; and
characterized by a second phase balance between the second transmitted port and the second coupled port substantially similar to the first phase balance.

### Claim 6 (depends on 5)

The system of claim 5, further comprising:
an attenuator:
electromagnetically interposed between the first coupled port of the first passive coupling device and the first signal processor; and
characterized by a first group delay; and
an amplifier:
electromagnetically interposed between the second coupled port of the second passive coupling device and the second signal processor; and
characterized by a second group delay substantially similar to the first group delay.

### Claim 7

A system for generating a self-receive signal comprising:
a signal generator;
a first signal processor;
a second signal processor;
an antenna;
a transmit chain:
electromagnetically coupling the signal generator to the antenna; and
configured to effect a first phase delay for a transmitted signal coupled from the signal generator to the antenna;
a receive chain:
electromagnetically coupling the antenna to the second signal processor;
comprising a receive signal path length; and
characterized by a second phase delay for a received signal coupled from the antenna to the second signal processor; and
a self-receive chain:
electromagnetically coupling the signal generator to the first signal processor;
comprising a self-receive signal path length substantially similar to the receive signal path length; and
configured to effect a third phase delay for a self-receive signal coupled from the signal generator to the first signal processor, the third phase delay substantially similar to the first phase delay and the second phase delay.

### Claim 8 (depends on 7)

The system of claim 7:
further comprising a clock; and
wherein the first signal processor is configured to, subsequent to reception of the self-receive signal, calculate a time-of-arrival of the self-receive signal based on the clock, the time-of-arrival approximating a time-of-departure for the transmitted signal according to the clock.

### Claim 9 (depends on 7)

The system of claim 7:
wherein the self-receive chain is characterized by a self-receive signal path length further comprises a self-receive propagation delay; and
wherein the receive chain is characterized by a receive signal path length further comprises a receive propagation delay substantially similar to the self-receive propagation delay substantially equal to the self receive signal path length.

### Claim 10 (depends on 7)

The system of claim 7:
wherein the first signal processor comprises a first analog-to-digital converter configured to generate digital samples according to a timestamp counter; and
wherein the second signal processor comprises a second analog-to-digital converter configured to generate digital samples according to the timestamp counter.

### Claim 11 (depends on 7)

The system of claim 7, further comprising a first passive coupling device:
comprising a first input port electromagnetically coupled to the signal generator;
comprising a first transmitted port electrically coupled to the antenna; and
comprising a first coupled port electromagnetically coupled to the first signal processor.

### Claim 12 (depends on 11)

The system of claim 11:
further comprising a power amplifier electromagnetically coupled between the signal processor and the first input port;
wherein the transmit chain comprises the power amplifier and the first passive coupling device via the first transmitted port; and
wherein the self-receive chain comprises the power amplifier and the first passive coupling device via the first coupled port.

### Claim 13 (depends on 11)

The method of claim 11, further comprising a second passive coupling device:
comprising a second input port electromagnetically coupled to the antenna;
comprising a second transmitted port electromagnetically coupled to the first transmitted port; and
comprising a second coupled port electromagnetically coupled to the second signal processor.

### Claim 14 (depends on 13)

The system of claim 13:
further comprising:
an attenuator electromagnetically interposed between the first coupled port and the first signal processor; and
a low-noise amplifier electromagnetically interposed between the second coupled port and the second signal processor;
wherein the self-receive chain comprises the attenuator and the first passive coupling device via the first coupled port; and
wherein the receive chain comprises the low-noise amplifier and the second passive coupling device via the second coupled port.

### Claim 15 (depends on 7)

The system of claim 7, further comprising a power combiner to merge the self-receive chain and the receive chain into the first signal processor to generate the self-receive signals comprising:
a self-receive signal port electromagnetically coupled to a coupled port of the first passive coupling device;
a receive signal port electromagnetically coupled to a coupled port of the second passive coupling device; and
a combined port electromagnetically coupled to the first signal processor.

### Claim 16

A system for generating a self-receive signal comprising:
a signal generator;
a set of signal processors;
an antenna;
a transmit chain:
electromagnetically coupling the signal generator to the antenna; and
configured to effect a first phase delay for a transmitted signal coupled from the signal generator to the antenna;
a receive chain:
electromagnetically coupling the antenna to a processor in the set of signal processors via a first passive coupling device;
characterizing a first propagation delay defined by a receive signal path length; and
characterized by a second phase delay for a receive signal coupled from the antenna to the set of signal processors; and
a self-receive chain:
electromagnetically coupling the signal generator to the set of signal processors via a second passive coupling device;
characterizing a second propagation delay defined by a self-receive signal path length substantially similar to the first propagation delay, the first and second propagation delays specifying a time-of-arrival of the receive signal and a self-receive signal at a transceiver associated with the system; and
configured to effect a third phase delay for the self-receive signal coupled from the signal generator to the set of signal processors, the third phase delay substantially similar to the first phase delay and the second phase delay.

### Claim 17 (depends on 16)

The system of claim 16:
wherein the set of signal processor comprises a first signal processor;
further comprising a multiplexer comprising:
self-receive signal port;
a receive signal port; and
an output port electromagnetically coupled to the first signal processor;
wherein the self-receive chain comprises the multiplexer via the self-receive signal port; and
wherein the receive chain comprises the multiplexer via the receive signal port.

### Claim 18 (depends on 17)

The system of claim 17, further comprising a digital controller electromagnetically coupled to the multiplexer and configured to:
select the self-receive signal port during a transmit slot in a time-division multiple access frame; and
select the receive signal port during a receive slot in the time-division multiple access frame.

### Claim 19 (depends on 16)

The system of claim 16:
wherein the set of signal processors comprises a first signal processor;
further comprising a power combiner comprising:
a self-receive signal port;
a receive signal port; and
an output port electromagnetically coupled to the first signal processor;
wherein the self-receive chain comprises the power combiner via the self-receive signal port; and
wherein the receive chain comprises the power combiner via the receive signal port.

### Claim 20 (depends on 16)

The system of claim 16:
wherein the set of signal processors comprises:
a first signal processor; and
a second signal processor; and
further comprising:
the self-receive chain electromagnetically coupling the signal generator to the first signal processor; and
the receive chain electromagnetically coupling the antenna to the second signal processor.