Method and apparatus for transmission line testing

1. A method comprising:

applying, at a customer premises device, a test signal to a transmission line coupled to the customer premises device;

measuring, at the customer premises device, a reflection of the test signal;

determining, at the customer premises device, a characteristic of the transmission line based on the reflection of the test signal;

determining, at the customer premises device, whether the transmission line supports a transmission service based on the characteristic; and

generating an output at the customer premises device, the output indicative of whether the transmission line supports the transmission service.

2. The method of claim 1 , wherein the characteristic includes an estimated achievable data rate of the transmission line.

3. The method of claim 1 , wherein generating the output includes initiating display of an indicator of service qualification.

4. The method of claim 1 , wherein after the customer premises device determines that the transmission line supports the transmission service, the customer premises device enables a computing device coupled to the customer premises device to send and receive data via the transmission line.

5. The method of claim 4 , wherein the customer premises device and the computing device are incorporated into a personal computer.

6. The method of claim 1 , wherein the customer premises device is located within a customer premises, and wherein the customer premises device includes a modem.

7. The method of claim 6 , wherein the modem enables a computing device distinct from the customer premises device to communicate with a remote server via a digital network.

8. The method of claim 1 , further comprising performing a transmission line test stored at a memory of the customer premises device, wherein the characteristic is determined based on a result of the transmission line test.

9. The method of claim 8 , wherein the transmission line test includes:

measuring background noise power in a frequency band at a connection to the transmission line;

measuring a voltage between a first conductor and a second conductor of the transmission line; and

measuring a capacitance between the first conductor and the second conductor of the transmission line.

10. The method of claim 1 , wherein the test signal includes a tone, and wherein the characteristic is based on an amplitude and a phase reflection of the tone.

11. The method of claim 1 , wherein the test signal is a pulse signal, and wherein the characteristic is based on an amplitude and a delay of a reflection of the pulse signal.

12. The method of claim 1 , further comprising:

applying a voltage step to the transmission line;

determining a time constant of the transmission line based on a current flow associated with the voltage step;

estimating a capacitance of the transmission line based on the time constant;

estimating a length of the transmission line based on the capacitance; and

generating an estimated broadband attenuation of the transmission line based on the length,

wherein the characteristic is based on the estimated broadband attenuation.

13. The method of claim 12 , wherein the test signal includes a voltage pulse, the method further comprising:

determining that a bridge tap exists at the transmission line based on a number and an amplitude of reflected pulses; and

adjusting the estimated broadband attenuation based on the determination that the bridge tap exists at the transmission line.

14. The method of claim 1 , wherein the test signal includes a tone frequency sweep, the method further comprising determining non-linear distortion associated with the transmission line based on the reflection, wherein the characteristic is based on the non-linear distortion.

15. The method of claim 1 , further comprising:

generating a predicted signal power of a signal received at the customer premises device based on a nominal signal power and based on an estimated broadband attenuation;

generating a predicted noise power associated with the transmission line based on measured background noise; and

generating a predicted signal-to-noise ratio based on the predicted signal power and the predicted noise power,

wherein the characteristic is based on the predicted signal-to-noise ratio.

16. The method of claim 1 , wherein determining the characteristic is performed independent of signals received by the customer premises device from other network devices via the transmission line.

17. An apparatus comprising:

a transmission line interface to connect to a transmission line;

a processor; and

a memory storing instructions that, when executed by the processor, cause the processor to perform operations comprising:

applying, at a customer premises device, a test signal to the transmission line coupled to the customer premises device;

measuring, at the customer premises device, a reflection of the test signal;

determining whether the transmission line supports a transmission service based on the reflection of the test signal; and

generating an output indicative of whether the transmission line supports the transmission service.

18. The apparatus of claim 17 , wherein the processor and the memory are within a modem within the customer premises device.

19. A processor-readable storage device storing instructions that, when executed by a processor, cause the processor to perform operations comprising:

applying, at a customer premises device, a test signal to a transmission line coupled to the customer premises device;

measuring, at the customer premises device, a reflection of the test signal;

generating an estimated achievable data rate of the transmission line based on the reflection of the test signal;

determining whether the transmission line supports a transmission service based on the estimated achievable data rate;

generating an output indicative of whether the transmission line supports the transmission service; and

after generating the output, enabling a computing device to send and receive digital signals via the transmission line.

20. The processor-readable storage device of claim 19 , wherein the operations further comprise:

generating a predicted signal power of a signal based on a nominal signal power and on an estimated broadband attenuation;

generating a predicted noise power associated with the transmission line based on measured background noise; and

generating a predicted signal-to-noise ratio based on the predicted signal power and the predicted noise power, wherein the estimated achievable data rate is further based on the predicted signal-to-noise ratio.

21. The method of claim 3 , wherein the indicator of service qualification is displayed using at least one indicator light.