# US 9,438,464 B2 · System and method for IQ imbalance estimation > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 9,438,464 B2 - Document ID: US9438464B2 - Status: Granted - Kind: B2 - Application number: 14/871,290 - Filed: 2015-09-30 - Published: 2016-01-21 - Granted: 2016-09-06 - Earliest claimed: 2014-04-18 - Applicants: Entropic Communications, Inc. - Inventors: Michail Tsatsanis; Na Chen - Web page: https://patentgrep.com/patent/US9438464B2 ## CPC - H04L 27/3863: {Compensation for quadrature error in the received signal} - H04L 43/12: Network monitoring probes - H04L: TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION (arrangements common to telegraphic and telephonic communication H04M) ## Abstract A system for IQ balance estimation is disclosed and may include requesting an in-phase and quadrature (IQ) probe comprising tones, receiving the tones with a frequency separation between images of the tones, the frequency separation being a result of a frequency shift at a requestor of the IQ probe, and calculating an estimate of IQ imbalance for each received tone. The system may also include requesting an IQ probe, receiving the tones with a frequency separation, and calculating an estimate of IQ imbalance for each received tone by determining an image to tone ratio based on the received tones. The requesting of the IQ probe, the receiving of the tones, and the calculating of the image to tone ratio may be repeated the results of the calculations of the image to tone ratio may be averaged. Gain, phase, and delay parameters may be calculated to compensate for the IQ imbalance. ## Claims ### Claim 1 A method, comprising: in a first communication device: requesting an in-phase and quadrature (IQ) probe from a second communication device external to the first communication device, the IQ probe comprising tones; receiving the tones from the second communication device with a frequency separation; and calculating an estimate of IQ imbalance for each received tone by determining an image to tone ratio based on the received tones. ### Claim 2 (depends on 1) The method of claim 1, comprising repeating the requesting of the IQ probe, the receiving of the tones, and the calculating of the image to tone ratio, and averaging the results of the calculations of the image to tone ratio. ### Claim 3 A method, comprising: in a first communication device: requesting an in-phase and quadrature (IQ) probe from a second communication device external to the first communication device, the IQ probe comprising tones; receiving the tones from the second communication device with a frequency separation between images of the tones, the frequency separation being a result of a frequency shift at the first communication device of the IQ probe; and calculating an estimate of IQ imbalance for each received tone. ### Claim 4 (depends on 3) The method of claim 3, comprising calculating gain, phase, and delay parameters to compensate for the IQ imbalance. ### Claim 5 (depends on 4) The method of claim 4, wherein the IQ imbalance comprises a receiver IQ imbalance. ### Claim 6 (depends on 3) The method of claim 3, comprising requesting a loopback probe comprising tones in a loopback circuit including a receiver and transmitter of the first communication device. ### Claim 7 (depends on 6) The method of claim 6, comprising receiving the tones transmitted via the loopback probe, and calculating gain, phase, and delay parameters to compensate for transmitter IQ imbalance. ### Claim 8 (depends on 3) The method of claim 3, wherein the estimated IQ imbalance includes a gain imbalance. ### Claim 9 (depends on 3) The method of claim 3, wherein the estimated IQ imbalance includes a phase imbalance. ### Claim 10 (depends on 3) The method of claim 3, wherein the estimated IQ imbalance estimate includes a delay imbalance. ### Claim 11 (depends on 3) The method of claim 3, wherein the frequency separation is selected as being large enough so that transmitter and receiver images of the tones do not interfere with each other. ### Claim 12 (depends on 3) The method of claim 3, wherein the frequency separation comprises 12.5 MHz. ### Claim 13 (depends on 3) The method of claim 3, wherein the first communication device comprises at least a receiver, and the second communication device, remotely located from the first communication device, comprises at least a transmitter. ### Claim 14 (depends on 13) The method of claim 13, wherein the first communication device comprises a MoCA 2.0 new node (NN) undergoing admission, and the second communication device comprises a MoCA 2.0 network controller (NC). ### Claim 15 (depends on 13) The method of claim 13, wherein the first communication device comprises a MoCA 2.0 existing node (EN), and the second communication device comprises at least one of a MoCA 2.0 NC or another MoCA 2.0 EN. ### Claim 16 A system for communication, the system comprising: a first communication device comprising a receiver and a transmitter, the first communication device being operable to: request an in-phase and quadrature (IQ) probe from a second communication device external to the first communication device, the IQ probe for transmitting tones; receive the tones from the second communication device with a frequency separation; and calculate an estimate of IQ imbalance for each received tone by determining the image to tone ratio based on the received tones. ### Claim 17 (depends on 16) The system of claim 16, wherein the IQ imbalance comprises an IQ imbalance associated with the receiver of the first communication device. ### Claim 18 (depends on 16) The system of claim 16, wherein the first communication device is operable to request a loopback probe comprising tones in a loopback circuit including the receiver and transmitter of the first communication device. ### Claim 19 (depends on 18) The system of claim 18, wherein the first communication device is operable to receive the tones transmitted via the loopback probe, and calculate gain, phase, and delay parameters to compensate for transmitter IQ imbalances. ### Claim 20 (depends on 16) The system of claim 16, wherein the frequency separation is selected as being large enough so that transmitter and receiver images of the transmitted tones do not interfere with each other. ### Claim 21 (depends on 16) The system of claim 16, wherein the request for the IQ probe is transmitted to the second communication device during admission of the first communication device to a network.