Abstract: Various aspects of the instant disclosure are directed towards communicating symbols over a power line carrying alternating current, based upon frequency variations in the alternating current. In accordance with some embodiments, a line driver couples data-carrying symbols over the power line, via a waveform. Variations in the alternating current are monitored and used for defining data useful for providing steps of the waveform. The accessed data entries are used to drive a line driver for modulating alternating current on the power line to account for the variations.

Abstract: Various aspects of the instant disclosure are directed towards communicating symbols over a power line carrying alternating current, based upon frequency variations in the alternating current. In accordance with some embodiments, a line driver couples data-carrying symbols over the power line, via a waveform. Variations in the alternating current are monitored and used for accessing a lookup table that stores data entries that define data useful for providing steps of the waveform. The accessed data entries are used to drive a line driver with stepped data, and therein modulating alternating current on the power line with the data-carrying symbols at a frequency that is tied to the frequency of the alternating current.

Abstract: Various aspects of the instant disclosure are directed towards communicating symbols over a power line carrying alternating current, based upon frequency variations in the alternating current. In accordance with some embodiments, a line driver couples data-carrying symbols over the power line, via a waveform. Variations in the alternating current are monitored and used for accessing a lookup table that stores data entries that define data useful for providing steps of the waveform. The accessed data entries are used to drive a line driver with stepped data, and therein modulating alternating current on the power line with the data-carrying symbols at a frequency that is tied to the frequency of the alternating current.

Abstract: Straight and arcuately curved superheater tube shields of refractory material comprising a pair of elongated half shields of identical interchangeable interfitting and interlocking size and shape, each half shield having a semicircular sidewall of corresponding straight or arcuate shape of predetermined radius of curvature extending between opposite ends and to inner diametrically opposite inner sides lying in a central plane and the plane of curvature. A number of mating camming portions with inclined camming surfaces are precisely spaced adjacent each of the inner sides so that one of the half shields may be turned end for end relative to and assembled to the other about a correspondingly shaped superheater tube by a relatively short axial movement and engagement of the inclined camming surfaces whereby the half shields are pulled together to close the joints therebetween and interlocked about the superheater tube. A refractory cement may be applied to attach the half shields to the tubes.

Abstract: A superheater tube shield of refractory material comprises a pair of elongated half shields of identical interchangeable interlocking size and shape, each half shield having a semi-circular sidewall portion extending between and to diametrically opposite tongue and groove side wall portions which are assembled together about the tubes by axially inserting elongaged tongues into the elongated grooves. Refractory cement may be applied to attach the half sheilds to the tubes.