GB1254820A - Improvements relating to information transmission systems - Google Patents

Abstract

1,254,820. Delta encoder. TEXAS INSTRUMENTS Ltd., and C. S. DENBRINKER. 3 July, 1970, No. 32490/70. Heading G4H. In a delta encoder (Fig. 1) in which the counter 3 in the transmitter is incremented or decremented one unit in accordance with whether an input at terminal 1 exceeds or is less than the previous input level represented by the count in counter 3 a count up/count down pulse being transmitted via a gate 7 through the receiver RX, when the counter is full or empty, gate 7 is inhibited and count up or count down pulses respectively are transmitted so that the receiver counter is stepped to bring it into synchronism with the transmitter counter. The counters ignore pulses tending to make them exceed their maximum and minimum values so that if the input is above the level represented by the counter 3 the counter will remain full at this time. If however the maximum count represents the maximum possible value of the input when the input is at its maximum the comparator 2 will result in alternate count up and count down signals being generated but the count down signals will not be transmitted since gate 7 is inhibited during them. As described the input signal is in analogue form the count in counter 3 being converted to analogue form in a D/A converter 4, gates 12, 13 connected to the outputs of counter 3 control the closing of gate 7 and the transmission of the pulses at full count and empty count. At the receiver a counter 15 accumulates the transmitted pulses, the counter outputs being connected to digital to analogue converter 16. Alternatively the input or output could be digital. The system may be modified to transmit three state signals representing count up, count down and no change instead of the two state signals of the embodiment of Fig. 1.