Apparatus and method for reduction of wireless links noise injection to a DOCSIS cable modem service
A DOCSIS cable modem service can be extended by providing wireless links that connect users that are beyond the physical reach of the system. This may require that the downstream data are transferred over a wireless link to a remote subscriber radio frequency (RF) unit connected to a cable modem that provides the downstream data to the subscriber. Similarly, upstream data are sent from the subscriber cable modem over the wireless link to the wireless hub transceiver, where such data are inserted back to the distribution coax cable. This insertion causes the injection of noise into the DOCSIS cable modem system. Connecting a plurality of such devices can cause noise beyond the system limitations. By using a burst detect system, the RF receiver portion of the device is connected to the DOCSIS cable only when injecting data upstream, thereby reducing the overall noise injection.
1 . An apparatus for reducing noise injection from a wireless device that is configured to insert upstream data to a DOCSIS cable modem, comprising:
a variable gain amplifier (VGA) for maintaining an input signal provided to said DOCSIS cable modem at a level that is sufficient for injection to said DOCSIS cable modem;
a burst detector for detecting when an upstream data burst from said wireless device is present; and
a linear variable gain amplifier (LVGA) connected to said VGA, said LGA operating under control of said burst detector to inject to said DOCSIS cable modem when said data are detected by said burst detector and to disconnect said apparatus from said DOCSIS cable modem when no upstream data are available.
2 . The apparatus of claim 1 , said apparatus comprising an integrated circuit.
3 . The apparatus of claim 1 , further comprising:
temperature compensation means.
4 . The apparatus of claim 1 , further comprising:
noise floor sampling means.
5 . A method for reducing noise injection from a wireless device that is configured to insert upstream data to a DOCSIS cable modem, comprising the steps of:
detecting an upstream data burst from said wireless device;
adjusting said upstream data signal level to a level that is compatible with levels required by said DOCSIS cable mode;
inserting said adjusted upstream data signal to said DOCSIS cable modem when said upstream data are detected; and
effectively disconnecting said DOCSIS cable modem when said upstream data are not detected.