GB1446679A - Telephone data set - Google Patents

Abstract

1446679 Substation apparatus; pulse circuits NORTHERN ELECTRIC CO Ltd 5 Dec 1974 [6 Dec 1973] 52662/74 Headings H4K and H3T In a push button data sender in which data to be transmitted can be set up in a storage means prior to transmission the data signals and a telephone handset are coupled to the line via a hybrid. As described the device may be used both as a data sender and a repeat dialler. All signals transmitted may be in multi-frequency form or the first digit train transmitted may be in impulse form (for dialling) with subsequent data transmission in multi-frequency form, an automatic sender arrangement for this mode being detailed in Fig. 5, not shown. The Figure shows a keypad 20 which provides markings in 1 out of 4 and 1 out of 3 form to a decoder 21 which applies the digits in binary form to a memory 22. The locations of the memory are repeatedly read by a display address generator and the contents of each location are read out (non-destructively) to a LED 8 bar code decoder 29. The code is applied via a driver 30 to the corresponding digit display identified by decoding at 31 the display address generator. The display appears to be continuously illuminated. If the correct number has been entered the # key is depressed causing the memory address generator to address the memory locations gating the digits to the sender. Writing into the memory is initiated in response to operation of the * key. An error correct key 35 is provided. One depression of this key deletes the last digit entered while a double depression clears the memory. An anti-contact-bounce circuit 34 comprises a two stage counter 340 which if it is allowed to count of 3 pulses from a clock 28, without being reset by NOR gate 345 by interrupts in a signal from a key 20 or 35, sets a bi-stable 342 until the key is released and provides a two millisecond output strobe pulse at 344, the duration of which is determined by the clock driving the counter to zero.