Abstract: A received signal train V(X) having a code length of 19 bits, in which an error correcting code is added on the basis of a generator polynominal G(X) of degree 11, is converted into a signal train V.sub.I (X) obtained by reversing an arrangement order from MSB to LSB in V(X) so that LSB in V(X) is positinoed in MSB in V.sub.I (X), . . . , and MSB in V(X) is positioned in LSB in V.sub.I (X) and then, the signal train V.sub.I (X) is divided by an inverse generator polynominal G.sub.I (X) of the generator polynominal G(X). A judgement is made on the number of "1"s in the resulting 11-bit syndrome S.sub.I (X). If the number is one or zero, single-bit error correction is performed by MOD2 addition of the received signal train V(X) and the syndrome S.sub.I (X). On the other hand, remaining 6 bits in occurrence of a primary error are read out from a ROM 13 with the address of particular 5 bits in the syndrome S.sub.I (X).

Abstract: A received signal train V(X), to which a BCH error correcting code is added on the basis of a generator polynominal G(X)=X.sup.12 +X.sup.10 +X.sup.8 +X.sup.5 +X.sup.4 +X.sup.3 +1, is divided by primative polynominals G.sub.1 (X)=X.sup.6 +X+1 and G.sub.2 (X)=X.sup.6 +X.sup.4 +X.sup.2 +X+1 resulting from factorization of G(X), to obtain syndromes S.sub.1 (X) and S.sub.2 (X) respectively. A single-bit error position .lambda. of the signal train V(X) is obtained from a first ROM table with the address of the syndrome S.sub.1 (X). Among values of the syndrome S.sub.2 (X) corresponding to single-bit errors, a syndrome S.sub.2 '(X) corresponding to the single-bit error position .lambda. is calculated from a second ROM table, to be compared with the syndrome S.sub.2 (X) obtained by dividing the received signal train V(X) by the primitive polynominal G.sub.2 (X). Upon coincidence of the synchromes S.sub.2 '(X) and S.sub.2 (X), a judgement is made on a primitive error, to perform correction.

Abstract: A diaphragm for a dynamic cone speaker which is composed of a porous metal produced from a metal such as nickel, wherein a layer, such as of aluminum foil, is disposed on a surface of the porous metal to eliminate the gas permeability of the porous metal.

Abstract: A diaphragm for a dynamic cone speaker which is composed of a porous metal produced from nickel powder wherein a vinyl chloride sheet is disposed on the surface of the porous metal to eliminate the gas permeability of the porous metal.