Patent GB-1274840-A (GB)
Title: Consol radio navigation receiver
IPC: G01S1/56
Filed: 1970-07-21
Abstract: 1,274,840. Radio navigation. STATRONIC A.S. 21 July, 1970 [1 Aug., 1969], No.35245/70. Heading H4D. In a Consol radio navigation receiver signal processing means comprises a calculator with inputs from a pulse filter and outputs to a digital position indicator 5, Fig. 3. The calculator provides for determination of the envelope intersection point within the equi-signal zone, even although it may be near the beginning or the end of the signal sequence, so that pulses are initially missed (Figs. 1b, 1c). As described, dot and dash signal pulses are respectively fed from the pulse filter to inputs P, S of a pulse selector circuit 13, which transfers all pulses x of the type first received via a first input of an OR circuit 14 to a first register 11. The pulse filter also feeds the pulses x, and the subsequent pulses y of the other type, via a first input (P+S) of an OR circuit 15 to a second register 12. Pulses from a first auxiliary pulse generator 16 are fed to a second input of the OR circuit 14, and every second pulse from a second auxiliary pulse generator 17 is fed to a third input of the OR circuit 14. All pulses from the generator 17 are fed to a second input of the OR circuit 15. The generator 16 operates at the standard Consol pulsing rate, and the generator 17 operates at a faster rate. With a signal sequence as shown in Fig. 1a, the pulses x are first counted into the registers 11 and 12 and the pulses y are then also counted into the register 12. At the end of the signal sequence, a start signal is given to an input T of the generator 17, which then pulses into the register 12 until the number'60 is reached, when a stop signal is given to an input U. The generator 17 thus provides 60-(x+y) pulses, and half of these are'fed via the third input of the OR-circuit 14 to the register 11, giving a total W, where W=x+[60-(x+y)]/2, for transfer to the indicator 5 as the corrected position of the intersection point. With signal sequences as shown in Figs. 1b and 1c there are time intervals a and b at the beginning and end of the detectable pulses x in the signal sequence. In these cases, a start signal is 'given to an input BB of the generator 16 when the carrier wave is detected. Pulses equivalent to a are fed into the register 11, the generator 16 being stopped when the first signal pulse arrives at the input (P+S). The pulses x are then counted into both registers and, finally, the generator 17 feeds (60-x) pulses to the register 12 and (60-x)/2 pulses to the register 11, giving a total fed to the latter of a+x+[(60-x)/2]. In the case of Fig. 1b, this total is less than 60 (since a is less'than (60-x)/2) and it may be expressed as W=60-[(b-a)/2], which is the corrected position of the intersection point, for transfer to'the indicator 5. In the case of Fig. 1c, the total is greater than 60 (since a is greater than (60-x)/2). 'It is accordingly arranged that a flip-flop 'circuit 18 is set by an output pulse from the register 11, and that it in turn applies, a control pulse back to a sign inverter 19. The indicator 5 will show the corrected position of the intersection point as W=60-[(b-a)/2]-60=(a-b)/2.