Abstract: There is described a process for adhering a first elongate foam element having a first end portion to a second elongate foam element having a second end portion. The process comprises an initial step of melting a first surface portion of the first end portion to produce a first molten portion. Next the first end portion is abutted to the second end portion. Thereafter, the first molten portion is caused to solidify to create a seam bond between the first end portion and the second end portion. Thus, the present invention relates to adhering two elongate foam elements together at their end portions. The bond between the foam elements is created by melting at least a portion of the surface of one or both of the end portions of the two foam buns. This creates insitu a molten region which acts as an adhesive when the end portions of the two buns are abutted or otherwise contacted with each other.

Abstract: A circuit and method for compressing or generating a pulse, particularly a chirp pulse, which uses infinite impulse response filtering (3.2). The infinite impulse response filters (3.9, 3.10, 3.11, 3.12) simulate the responses of finite impulse response filters. This is achieved by pre-processing the signal by passing it through a pre-processing filter (3.3) which has zero response at the resonant frequencies of the infinite impulse response filters (3.9, 3.10, 3.11, 3.12). The pre-processing and infinite impulse response filtering may be incorporated into a matched filter for detection of a chirp waveform input signal. This can be implemented in the time domain or the frequency domain. The matched filter also can incorporate beating to the base band techniques. The matched filter can also act as a generator by applying a pulse to the input which has the unit impulse function causing a chirp signal, equivalent to the transfer function of the filter, to be produced as the output.