Channel scanning
Methods, systems, and apparatus can provide channel scanning. In various examples, a channel scanning module can instruct scanning of multiple channels within a wideband frequency range by assigning channels to one or more demodulators to attempt to lock onto a signal at the assigned channel. In other examples, a channel scanning module can instruct scanning for downstream channels by assigning channels to multiple narrowband tuners and multiple demodulators to attempt to lock onto a signal on the assigned channel.
1. A method for channel scanning comprising:
receiving a downstream network signal;
identifying a wideband frequency block in the network signal;
waiting an amount of time for local oscillators to settle;
identifying one or more subfrequencies within the wideband frequency block for a demodulator to attempt to lock;
attempting to lock onto a subfrequency with a plurality of demodulators the attempt to lock onto a subfrequency comprising an attempt to identify a data over cable service interface specification (DOCSIS) data signal within the subfrequency; and
performing ranging and registration for the subfrequency if demodulator lock has been achieved for the subfrequency by one or more of the plurality of demodulators.
2. The method of claim 1 , wherein demodulator lock has been achieved for a subfrequency when five consecutive packets with a correct forward error correction check within the data stream for the subfrequency are received.
3. The method of claim 1 , wherein the method further comprises attempting to lock onto a second subfrequency with a second demodulator if demodulator lock has not been achieved for the subfrequency.
4. The method of claim 1 , wherein identifying one or more subfrequencies is performed using a scanning algorithm.
5. The method of claim 1 , wherein the scanning algorithm comprises going through the subfrequencies in order.
6. The method of claim 3 , wherein the order comprises going from lowest subfrequency to highest subfrequency.
7. The method of claim 3 , wherein the order comprises going from highest subfrequency to lowest subfrequency.
8. The method of claim 1 , wherein the scanning algorithm comprises going through the frequencies in the order of most common use.
9. The method of claim 1 , wherein the scanning algorithm comprises going through the frequencies beginning with the frequencies stored in a memory.
10. The method of claim 1 , wherein the scanning algorithm comprises going through the frequencies beginning with the subfrequencies having the highest signal energy.
11. The method of claim 1 , further comprising:
identifying a second wideband frequency block in the network signal if no lock has been achieved on any subfrequency;
waiting an amount of time for local oscillators to settle;
identifying one or more subfrequencies within the second wideband frequency block for a demodulator to attempt to lock;
attempting to lock onto a subfrequency within the second wideband frequency block with a demodulator; and
performing ranging and registration for the subfrequency within the second wideband frequency block if demodulator lock has been achieved for the subfrequency within the second wideband frequency block.
12. The method of claim 1 , further comprising:
identifying a second wideband frequency block in the network signal if ranging/registration was unsuccessful for all of the subfrequencies;
waiting an amount of time for local oscillators to settle;
identifying one or more subfrequencies within the second wideband frequency block for a demodulator to attempt to lock;
attempting to lock onto a subfrequency within the second wideband frequency block with a demodulator; and
performing ranging and registration for the subfrequency within the second wideband frequency block if demodulator lock has been achieved for the subfrequency within the second wideband frequency block.
13. A method for channel scanning comprising:
receiving a downstream network signal;
identifying a wideband frequency block in the network signal;
waiting an amount of time for local oscillators to settle;
identifying one or more subfrequencies within the wideband frequency block for a demodulator to attempt to lock;
attempting to lock onto a subfrequency with a plurality of demodulators, the attempt to lock onto a subfrequency comprising an attempt to identify a data over cable service interface specification (DOCSIS) data signal within the subfrequency; and
recursively performing ranging and registration for all subfrequencies for which lock was achieved by any of the plurality of demodulators acting in parallel.
14. A method for channel scanning comprising:
receiving a downstream network signal;
identifying a plurality of frequencies in the network signals;
waiting for local oscillators to settle on the plurality of frequencies;
attempting to lock onto any of the identified plurality of frequencies with a plurality of demodulators, the attempt to lock onto a frequency comprising an attempt to identify a data over cable service interface specification (DOCSIS) data signal within the frequency; and
if any of the plurality of demodulators has achieved lock for any one of the identified plurality of frequencies, performing ranging and registration for the particular frequency.
15. The method of claim 14 , wherein the method further comprises attempting to lock onto a second frequency with a second demodulator among the plurality of demodulators if demodulator lock has not been achieved for a first frequency selected by a first demodulator among the plurality of demodulators.
16. The method of claim 14 , wherein a demodulator from the plurality of demodulators has achieved lock for a particular frequency when five consecutive packets with a forward error correction check within the data stream for the particular frequency are received.
17. The method of claim 14 , wherein if no lock has been achieved on any frequency, identifying a second plurality of frequencies in the network signals;
waiting for local oscillators to settle on the second plurality of frequencies;
attempting to lock onto any of the identified second plurality of frequencies with a plurality of demodulators; and
if any of the plurality of demodulators has achieved lock for a particular frequency of the second plurality of frequencies, performing ranging and registration for the particular frequency.
18. The method of claim 14 , wherein if ranging/registration unsuccessful for all of the frequencies for which lock was achieved, select a second plurality of frequencies identifying a second plurality of frequencies in the network signals;
waiting for local oscillators to settle on the second plurality of frequencies;
attempting to lock onto any of the identified second plurality of frequencies with a plurality of demodulators; and
if any of the plurality of demodulators has achieved lock for a particular frequency of the second plurality of frequencies, performing ranging and registration for the particular frequency.
19. A method for channel scanning comprising:
receiving a downstream network signal;
identifying a plurality of frequencies in the network signals;
waiting for local oscillators to settle on the plurality of frequencies;
attempting to lock onto any of the identified plurality of frequencies with a plurality of demodulators the attempt to lock onto a frequency comprising an attempt to identify a data over cable service interface specification (DOCSIS) data signal within the frequency; and
recursively performing ranging and registration for all frequencies for which lock was achieved by any demodulator acting in parallel.
20. The method of claim 19 , wherein if no lock has been achieved on any frequency, identifying a second plurality of frequencies in the network signals;
waiting for local oscillators to settle on the second plurality of frequencies;
attempting to lock onto any of the identified second plurality of frequencies with a plurality of demodulators; and
recursively performing ranging and registration for all frequencies of the second plurality of frequencies for which lock was achieved by any demodulator acting in parallel.