An apparatus for characterising an input signal within abroad frequency band by comparing the same input signal in a plurality of channels, in order to operate digital Electronic Support Measures which require a broad bandwidth to function. Each block of data includes an array of bits logically organized into rows and columns, including a column including row-checkbits, a column including inner checkbits and data bits, and columns containing data bits. Coating agents such as alcohols, glycols, polyols, vegetable oil, and mineral oils may help apply the nanoparticles to the surfaces of structures in the filter beds or packs. The method also includes transmitting the packet onto a network, the packet being transmitted in its original position relative to the other packets. The succeeding winding drum is positioned lower than the leading winding drum such that the succeeding winding drum supports a greater proportion of the weight of a forming web roll when the roll is in a winding position supported by both the leading and succeeding winding drums. The compounds are generally aryl sulfonamide derivatives and are useful in pharmaceutical compositions, methods for the treatment of CCR9-mediated diseases, and as controls in assays for the identification of CCR9 antagonists.