Systems and methods for loop length and bridged tap length determination of a transmission line
Through the use of a least squares minimization concept, the loop length, the number of bridged taps and length of the bridged taps on a transmission line can be determined from readily available modem data. In particular, the loop length, the number of bridge taps and the length of bridged taps can be estimated by comparing a measured frequency domain channel impulse response of the transmission line to a model of a loop that is comprised of multiple sections and multiple bridge taps.
1. An upstream data loop length and tap length estimation system comprising:
a reverb signal determination device that determines a measured transfer function of a transmission line by averaging a plurality of reverb signals;
an impedance detector that detects a frequency domain impedance of a specified wire gauge;
controller circuitry that determines a frequency domain propagation function for the specified wire gauge input from a storage device, the controller circuitry is configured to:
determine a transmit impedance of a customer-premises equipment, CPE, modem;
determine a receive impedance of a central office, CO, modem;
determine a matrix representing frequency domain responses of a plurality of sections of a loop representing the transmission line, the matrix further including a frequency response of a bridged tap, and an F S matrix and an F L matrix respectfully representing analog front end circuitry for source (TX) and load (RX) paths;
estimate an actual transfer function (H) based on the frequency domain responses of the plurality of sections of the loop, and the frequency response of the bridged tap, the F S matrix, and the F L matrix; and
input calibrated and compensated reverb signals in the frequency domain, and input a reference gauge of the wire from the storage device; and
a modem identification determining device that determines an identification of the CO modem collecting the reverb signals, and an identification of the CPE modem transmitting the reverb signals,
wherein since a number of elements in a receive function is known, the controller circuitry is further configured to minimize a difference between the actual transfer function and the measured transfer function in order to determine and output both the estimated loop length and the estimated bridged tap length.
2. The system of claim 1 , wherein the controller circuitry is further configured to minimize the difference under an assumption that the transmission line is not perfectly terminated.
3. The system of claim 1 , further comprising the CO modem or the CPE modem being initialized.
4. The system of claim 1 , wherein the specified wire gauge is input to the storage device.
5. The system of claim 1 , wherein the estimated loop length and the estimated bridged tap length are also applicable to a downstream path.
6. The system of claim 1 , wherein the estimated loop length is output to one or more of a computer, a laptop, a terminal, and a transmission line testing device.
7. The system of claim 1 , wherein the estimated bridged tap length is output to one or more of a computer, a laptop, a terminal, and a transmission line testing device.
8. An upstream data loop length and tap length estimation method comprising:
determining, with reverb signal processing circuitry, a measured transfer function of a transmission line by averaging a plurality of reverb signals;
determining, with controller circuitry, a frequency domain propagation function for a specified wire gauge input from a storage device;
detecting, with an impedance detector, a frequency domain impedance of the specified wire gauge;
determining, with the controller circuitry, a transmit impedance of a customer-premises equipment, CPE, modem;
determining, with the controller circuitry, a receive impedance of a central office, CO, modem;
determining, with the controller circuitry, a matrix representing frequency domain responses of a plurality of sections of a loop representing the transmission line, the matrix including a frequency response of a bridged tap, and an F S matrix and an F L matrix respectively representing analog front end circuitry for source (TX) and load (RX) paths;
estimating, with the controller circuitry, an actual transfer function (H) based on the frequency domain responses of the plurality of sections of the loop, the frequency response of the bridged tap, the F S matrix, and the F L matrix;
inputting calibrated and compensated reverb signals in the frequency domain, and inputting a reference gauge of the wire from the storage device;
determining an identification of the CO modem collecting the reverb signals, and an identification of the CPE modem transmitting the reverb signals; and
minimizing, with the controller circuitry, a difference between the actual transfer function and the measured transfer function, and determining and outputting both the estimated loop length and the estimated bridged tap length based upon the results of the minimized difference.
9. The method of claim 8 , wherein the transmission line is not perfectly terminated.
10. The method of claim 8 , wherein the CPE modem or the CO modem is initialized.
11. The method of claim 8 , wherein the specified wire gauge is input to the storage device.
12. The method of claim 8 , wherein the estimated loop length and the estimated bridged tap length are also applicable to a downstream direction.
13. The method of claim 8 , further comprising:
outputting the estimated loop length to one or more of a computer, a laptop, a terminal, and a transmission line testing device.
14. The method of claim 8 , further comprising:
outputting the estimated bridged tap length to one or more of a computer, a laptop, a terminal, and a transmission line testing device.