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专利名称：Alternating current signaling system发明人：HADFIELD BERTRAM MORTON申请号：US26952439申请日：19390422公开号：US2282129A公开日：19420505
摘要：514,520. Automatic exchange systems. HADFIELD, B. M. May 7, 1938, No. 136.[Class 40 (iv)] [Also in Group XL] In a system in which signals are sent in the form ofimpulses of alternating current which are translated into direct current impulses at thereceiving end, the signals pass through a frequency multiplying circuit before translation.In the arrangement shown, which is particularly suitable for single or multi-channel voicefrequency telegraph systems or for the reception of 750 cycle dialling impulsesin.telephony, the signals pass through two frequency doublers in cascade, the firstcomprising a pair of valves V1 and the second a full-wave rectifier RD, to a transformer T3tuned by a condenser C3 to the quadrupled frequency, and thence to a valve V2 whichcontrols a rectifying arrangement of the kind described in Specification 505,500, [GroupXL]. The direct current component derived from the rectifier RD is applied across aresistance R and by means of a condenser C and rectifier R1, R2 provides a negative biaswhich builds up quickly but decays slowly to render the valve V2 inoperative until thesignals in the tuned circuit T3, C3, reach one-half the peak voltage. Since all incomingfrequencies contribute to the biassing effect, the arrangement automatically preventsoperation by speech containing a proportion of the signalling- frequency.
申请人：ASSOCIATED ELECTRIC LABORATORIES INC.
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