Patent GB-1068493-A (GB)
Title: System for determining the mutual distance between two parallel planes
IPC: G06F19/00
Filed: 1964-07-01
Abstract: 1,068,493. Radio position flnding. TELEFUNKEN PATENTVERWERTUNGS G.m.b.H. July 1, 1964 [July 11, 1963], No. 27169/64. Heading H4D. A system for determining the distance i x , Fig. 1, between a position plane F p  including a point P and a parallel reference plane F o , using acoustic or electromagnetic waves, is characterized by the following features: (a) three transmitting points A, B and C are established on a line perpendicular to the planes F o  and Fp, the distance between points A and B being i 4 , between B and C, i 5 ; and between point C and plane F o , i 5 , i 6  being positive as shown, and negative when C is to the right of plane F 0 ; (b) a receiving point P is established on plane Fp at distances from points A, B and C of i 1 , i @  and i 3  respectively; (c) the path differences #i 12  = i i  - i 2 , #i 23  = i 2  - i 3  and #i 13  = i 1  - i 3  = #i 12  + #i 23  are calculated at point P by any known hyperbolic navigation method; (d) it is determined in which region, out of six possible regions plane F p  is situated, the regions being defined as follows: Region 1-i 1 >i 2 >i 3  such that #i 12  and #i 23  are positive; Region 2-i 1 >i 3 >i 2  or i 3 >i 1 >i 2  such that #i 12  is positive and #i 23  is negative ; Region 3-i 3 >i 2 >i 1 such that #i 12  and #i 23  are negative Region 4-i 1  = i 2 >i 3  such that #i 12  = O; Region 5-i 1 >i 2  = i 3  such that #i 23  = O Region 6-i 1  = i 3 >i 2  such that #i 12  = - #i 23 . (e) the form of the equations: is determined in view of the region in which F p  has been found to be in, wherein: For Region 1-#iv<SP>1</SP> = 2#i 23  + #i 12'  #-iy<SP>11</SP> = #i 23 , iv <SP>+</SP>= 2i 3 ; Region 2-#iv<SP>1</SP> = #i 12'  #i v <SP>11</SP> = - #i 23 , iv<SP>+</SP> = 2i 2 ; Region 3-#i v 1 = <SP>_</SP> #i 12 , #i v 11 = <SP>_</SP> (2#i 12 + #i 23 ), i v  + = 2i 2 ; the equations reducing as follows for the regions 4, 5 and 6: Region 4-i x  = i 4 /2 + i 5  + i 6  Region 5-i x  = i 5 /2 + i 6  Region 6-i x  = i 4  + i 5  / 2 + ie; (f) the following operations are carried out depending on which region is involved: (f 1 ) when plane F p  is in regions 1, 2 or 3, the terms p<SP>1</SP>i v , qi<SP>1</SP>, pi<SP>11</SP> v , and qi<SP>1</SP><SP>1</SP> v  are determined, wherein p<SP>1</SP>i v  = #i<SP>1</SP> v , #i 12  . ki<SP>1</SP> - i s <SP>1</SP> q<SP>1</SP>i = #i 12  . kli pi<SP>11</SP> v  = #i<SP>11</SP> v  . #i 23  . ki<SP>11</SP> - i<SP>11</SP> 5  qi<SP>11</SP> = #i 23  . ki<SP>11</SP>. (f 2 ) when plane Fp is in regions 4, 5 or 6, i x  is calculated from the known values of i 4 , i 5  and i 6 . (g) when plane F p  is in regions 1, 2 or 3, the sums Si<SP>1</SP>n and Si<SP>11</SP>n are determined, wherein: for n = 0, 1, 2, 3 &c., and (h) the sums Si<SP>1</SP>n and Si<SP>11</SP>n are compared for each value of n until they are found to be equal, whereupon the value of Si<SP>1</SP>n or Si<SP>11</SP>n   is the value i x . The signals used in the system must include timing marks, such as pulses, rising edges of rectangular-wave signals, passages through zero or peaks of sinusoidal oscillations, rapid changes in phase, or rapid changes in frequency or amplitude. In the described embodiment, the distances ix 1 , i 1 , i 2  ... #i 12  &c. are replaced by corresponding transmission times Tx, T 1'  T 2  .. #T 12  &c., the times being determined by counting the number of clock pulses occurring during the said time. A single pulse generator is used to feed all three transmitting stations so that the pulses emitted by the three stations must be staggered in time, and the pulse M, from station A which is emitted first must be immediately preceded by an identifying pulse Mi so that the pulse M 1  can be identified at the receiving point. Fig. 4 shows a possible arrangement of the transmitting stations A, B and C, together with a common pulse generator 1, wherein a pulse from generator 1 passes directly to the transmitter 5 of station A, and constitutes the identifying pulse Mi. The pulse also passes to the transmitter 5 via a delay 8, which introduces a delay of Ti, to be radiated as pulse M 1 . The pulse also passes to the transmitter 10 of station B via a delay 9, which introduces a delay of T<SP>1</SP>d+Ti 1  to be radiated as pulse M 2 . The pulse also passes to the transmitter 13 of station C via a delay 12, which introduces a delay of T<SP>11</SP>d + Ti, to be radiated as pulse M,. Fig. 5 shows timing separator equipment 18 at point P, whereby the pulses are identified and the delays T<SP>1</SP>d and T<SP>11</SP>d cancelled out, such that the only remaining differences in the time of arrival of the three pulses must be due to differences in the path lengths i 1 , i 2  and i 3 . The pulses are received by antenna 15 and receiver 16. The received pulses pass through AND gate 19, normally kept open by a signal on line 20. Before any pulses are received bi-stable circuits 23, 28, 32 and 36 are reset by a signal on line 24 such that the O part of each circuit gives an output and the L part does not. The Mi pulse passes through a delay 22, which introduces a delay of Ti, and so arrives at one input of AND gate 21, simultaneously with the arrival of pulse M 1  at the other input thereof. The pulse M 1  therefore passes through gate 21 and switches over circuit 23, such that the L part of the circuit now produces a signal. Pulse M 1  also passes via OR gate 25 to AND gates 27, 31 and 35. Gates 31 and 35 are closed since there is no signal at their inputs from the L parts of circuits 28 and 32 respectively. Gate 27 however is open and pulse M 1  passes therethrough to switch over circuit 28, such that a signal appears from the L part thereof which opens gate 31 and passes to delay 29. Delay 29 introduces a delay of Td<SP>11</SP> such that the pulse appearing on line 30 represents pulse M 1  compensated for its transmitted lead on pulse M,. Pulse M 2  similarly passes through gate 31 and causes circuit 32 to change over, so that gate 35 is opened and a pulse is fed to delay 33 which introduces a delay of Td<SP>11</SP>-Td<SP>1</SP> such that the pulse appearing on line 34 represents pulse M 2  compensated for its transmitted lead on pulse M 3 . Pulse M 3  similarly causes an undelayed pulse to appear on line 37. Any remaining difference in timing of pulses M 1 , M 2  and M, results from differences in the lengths i 1 , i 2  and i 3 . Fig. 6 shows the sequence determining circuit 38 receiving the pulses on lines 30, 34 and 37 and determining which region the plane Fp lies in. The reset signal on line 24 is applied to circuit 38 as well as circuit 18, and causes the O parts of bi-stable circuits 40, 41, 42, 43, 44, 45, 46 and 47 to produce signals. The signals from circuits 45, 46, 47 open AND gate 58 which in turn opens AND gates 59, 60 and 61, whilst the signals from circuits 42, 43 and 44 open AND gate 51 which in turn open AND gates 52, 53 and 54. Assuming that the plane Fp is in region 3, the pulses will be present at the output of circuit 18 in the order M 1 , M, and lastly M 3 . Pulse M 1  on line 30 passes through gates 52 and 59 to switch over circuit 47 such that a signal appears on line 70, indicating that pulse M 1  was first in the sequence, and gates 58, 59, 60 and 61 are closed. The signal from the L part of circuit 47 also passes through OR gate 63 to open AND gates 55, 56 and 57. The pulse M2 then appears on line 34 and passes via gates 53 and 56 to switch over circuit 43 such that a signal appears on line 68, indicating that pulse M 2  was second in the sequence, and gates 51, 52, 53 and 54 are closed. The signal from circuit 43 also passes through OR gate 62 to open AND gates 49 and 50. The pulse M 3  then appears on line 37 and passes via gate 49 to switch over circuit 40 such that a signal appears on line 66, indicating that pulse M 3  was least in the sequence, and gate 48 is closed. This last gate closure removes the signal from line 20 which kept gate 19 in the timing separator 18 open, such that no more pulses can enter the system. The pulses M 1 , M 2  and M 3  together with the signals on lines 65, 66, 67, 68, 69, 70, 71 and 72 pass to a measuring circuit 39, shown in detail in Fig. 7. In the measuring circuit, signals are fed to AND gate 92 on lines 65, 68 and 72 for region 1 to AND gate 91 on lines 65, 69 and 71 for region 2 where i 1 >i 3 >i 2 , to AND gate 90 on lines 66, 67 and 71 for region 2 where i 3 >i 1 >i 2 , and to AND gate 93 on lines 66, 68 and 70 for region 3. The outputs of gates 90 and 91 are combined in OR circuit 98. Simultaneous M 1  and M 2  signals on lines 30 and 34 pass through AND gate 83 for region 4. Simultaneous M 2  and M 3  signals on lines 34 and 37 pass through AND gate 84 for region 5. Simultaneous M 1  and M 3  signals on lines 30 and 37 pass through AND gate 85 for region 6. Since time is used instead of distance in the embodiment the two equations (A) and (B) are changed to: Oscillators 107, 109 and 111 generate pulses at repetition frequencies of f 1 , f 2  and f 3  respectively such that:  k 1 r  = 1/2T 4  = f 1  . f 2  . D r , k<SP>11</SP>T<SP> </SP>= 1/2T 5   = f 2  . f 3  D T , where D T  is the unit of time. Equation (A)<SP>1</SP> and (B)<SP>1</SP> can be written: The terms #T v <SP>1</SP> and #T v <SP>11</SP> vary with the region V in question, but are comprised of the times ATn, #T 23  in various combinations. Four pulse counts must therefore be made, namely: #T 12  À f 1  = bl #T 12  . f 2  = c<SP>1</SP> #T 23  . f 2  = c<SP>11</SP> #T 23  . f 3  = b<SP>11</SP>. In the region 1, a v <SP>1</SP> = c<SP>1</SP>+2c<SP>11</SP>, a v <SP>11 </SP>= c<SP>11</SP>. In region 2, a v <SP>1</SP> = c<SP>1</SP>, a v <SP>11</SP> = - c<SP>11</SP>. In region 3, a v <SP>1</SP> = - c<SP>1</SP>, a v <SP>11</SP> = - (2c<SP>1</SP>+c<SP>11</SP>). In the measuring circuit 39 all the bi-stable circuits are initially reset to the O state, by a signal on line 24 such that their L-parts give no output, a