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 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 first wideband frequency block in the network signal;
identifying a number of demodulators available in a communications device;
identifying a plurality of subfrequencies within the first wideband frequency block, wherein the plurality of subfrequencies identified matches a number of available demodulators;
for each respective one subfrequency of the identified plurality of subfrequencies, attempting to lock onto the respective one subfrequency with a respective one demodulator of the available demodulators, wherein the individual processes of attempting to lock onto each of the identified plurality of subfrequencies occur in parallel to each other;
identifying a first subfrequency from the identified plurality of subfrequencies on which one of the number of demodulators has achieved lock; and
performing ranging and registration for the first subfrequency if demodulator lock has been achieved for the first subfrequency by one or more of the demodulators.
2. The method of claim 1 , wherein demodulator lock has been achieved for the first subfrequency when five consecutive packets with a correct forward error correction check within a data stream for the first subfrequency are received.
3. The method of claim 1 , wherein identifying the plurality of subfrequencies is performed using a scanning algorithm.
4. The method of claim 3 , wherein the scanning algorithm comprises going through the subfrequencies in order.
5. The method of claim 4 , wherein the order comprises going from lowest subfrequency to highest subfrequency.
6. The method of claim 4 , wherein the order comprises going from highest subfrequency to lowest subfrequency.
7. The method of claim 3 , wherein the scanning algorithm comprises going through the frequencies in the order of most common use.
8. The method of claim 3 , wherein the scanning algorithm comprises going through the frequencies beginning with the frequencies stored in a memory.
9. The method of claim 3 , wherein the scanning algorithm comprises going through the frequencies beginning with the subfrequencies having the highest signal energy.
10. The method of claim 1 , further comprising:
identifying a second wideband frequency block in the network signal if no first subfrequency has been identified for any subfrequency in the first wideband frequency block;
identifying a second plurality of subfrequencies within the second wideband frequency block for the number of demodulators to attempt to lock, wherein the plurality of subfrequencies identified matches the number of demodulators available;
attempting to lock onto each of the identified second plurality of subfrequencies within the second wideband frequency block with a respective demodulator, wherein the individual processes of attempting to lock onto each of the identified second plurality of subfrequencies occur in parallel to each other;
identifying the first subfrequency from the identified plurality of subfrequencies on which one of the number of demodulators has achieved lock; and
performing ranging and registration for the first subfrequency within the second wideband frequency block if demodulator lock has been achieved for the first subfrequency within the second wideband frequency block.
11. The method of claim 1 , further comprising:
identifying a second wideband frequency block in the network signal if ranging and registration was unsuccessful for the identified first subfrequency in the first wideband frequency block;
identifying a second plurality of subfrequencies within the second wideband frequency block for the number of demodulators to attempt to lock, wherein the plurality of subfrequencies identified matches the number of demodulators available;
attempting to lock onto each of the identified second plurality of subfrequencies within the second wideband frequency block with a respective demodulator, wherein the individual processes of attempting to lock onto each of the identified second plurality of subfrequencies occur in parallel to each other; and
identifying a second subfrequency from the identified second plurality of subfrequencies on which one of the number of demodulators has achieved lock; and
performing ranging and registration for the second subfrequency within the second wideband frequency block if demodulator lock has been achieved for the second subfrequency within the second wideband frequency block.
12. A method for channel scanning comprising:
receiving a downstream network signal;
identifying a first wideband frequency block in the network signal;
identifying a first plurality of n subfrequencies within the first wideband frequency block for a plurality of n demodulators to attempt to lock;
attempting to lock onto the plurality of n subfrequencies with respective demodulators from the plurality of n demodulators to identify a data signal within one of the plurality of n subfrequencies; and
recursively performing ranging and registration for all subfrequencies from the plurality of subfrequencies for which lock was achieved by any of the plurality of demodulators acting in parallel.
13. The method of claim 12 , further comprising:
identifying a second wideband frequency block in the network signal if no lock has been achieved on any of the first plurality of n subfrequencies in the first wideband frequency block;
identifying a second plurality of n subfrequencies within the second wideband frequency block for a plurality of n demodulators to attempt to lock;
attempting to lock onto the second plurality of n subfrequencies within the second wideband frequency block with the plurality of n demodulators; and
performing ranging and registration for one or more second subfrequencies from the second plurality of n subfrequencies within the second wideband frequency block if one or more of the plurality of n demodulators has achieved lock for the one or more second subfrequencies from the second plurality of n subfrequencies within the second wideband frequency block.
14. The method of claim 12 , further comprising:
identifying a second wideband frequency block in the network signal if ranging and registration was unsuccessful for all of the first plurality of n subfrequencies;
identifying a second plurality of n subfrequencies within the second wideband frequency block for the plurality of n demodulators to attempt to lock;
attempting to lock onto the second plurality of n subfrequencies within the second wideband frequency block with the plurality of n demodulators; and
performing ranging and registration for all subfrequencies within the second wideband frequency block for which demodulator lock has been achieved within the second plurality of n subfrequencies within the second wideband frequency block.
15. The method of claim 12 , wherein demodulator lock has been achieved for any of the first plurality of n subfrequencies when five consecutive packets with a correct forward error correction check within the data stream for any of the first plurality of n subfrequencies are received.
16. A cable modem, comprising:
a communications interface operable to receive a downstream network signal;
a wideband tuner operable to receive identification of a first wideband frequency block in the network signal;
a processor operable to identify the first wideband frequency block for the wideband tuner and to identify a first plurality of subfrequencies within the first wideband frequency block for a demodulator to attempt to lock;
a plurality of demodulators operable to receive identification of the first plurality of subfrequencies in the wideband frequency block and to attempt to lock onto the plurality of subfrequencies to identify a data signal within one of the plurality of subfrequencies; and
the processor being further operable to recursively perform ranging and registration processes for all subfrequencies from the first plurality of subfrequencies for which lock was achieved by any of the plurality of demodulators acting in parallel.
17. The cable modem of claim 16 , further comprising:
the processor being further operable to identify a second wideband frequency block in the network signal and to instruct the wideband tuner to tune to the second wideband frequency block if no lock has been achieved on any of the first plurality of subfrequencies in the first wideband frequency block, and the processor is operable to identify a second plurality of subfrequencies within the second wideband frequency block for the plurality of demodulators to attempt to lock;
the plurality of demodulators being operable to attempt to lock onto the second plurality of subfrequencies within the second wideband frequency block; and
the network processor is further operable to perform ranging and registration for one or more second subfrequencies from the second plurality of subfrequencies within the second wideband frequency block if one or more of the plurality of demodulators has achieved lock for the one or more second subfrequencies from the second plurality of subfrequencies within the second wideband frequency block.
18. The cable modem of claim 16 , further comprising:
the processor being further operable to identify a second wideband frequency block in the network signal including identifying a second plurality of subfrequencies within the second wideband frequency block if ranging and registration was unsuccessful for all of the first plurality of subfrequencies;
the plurality of demodulators being operable to attempt to lock onto the second plurality of subfrequencies within the second wideband frequency block; and
the processor being further operable to perform ranging and registration processors for all subfrequencies within the second wideband frequency block for which demodulator lock has been achieved for the second plurality of subfrequencies within the second wideband frequency block.
19. The cable modem of claim 16 , wherein the cable modem is integrated into a set top box or an embedded multimedia terminal adapter.