Patent GB-756577-A (GB)
Title: Improvements in or relating to echo-sounding apparatus
Inventor: BOLZMANN HANS
IPC: G01S1/72
Filed: 1953-11-23
Abstract: 756,577. Echo-sounding and distancemeasuring apparatus. ELECTROACOUSTIC GES. Nov. 23, 1953, No. 32471/53. Class 118(2) Relates to underwater pulse-echo sonic ranging systems in which echoes received at any time in the pulse recurrence period are displayed on an electro-chemical recorder comprising a stylus attached to an endless carrier and echoes received during a selectable portion of said period are displayed on a cathode-ray tube. According to the present invention the transmitted pulse is initiated by actuation of a switch by mechanical means synchronized with movement of the stylus carrier and the selected portion of the recurrence period is initiated by the same switch or by a second similar switch, the timing being adjusted by mechanical displacement of said second switch or by using the switch to initiate an adjustable clockwork or electrical time delay. In the embodiment described the duration of the C.R.O. sweep waveform is equal to that of the reflected portion of the recurrence period and the initiation of the waveform is adjustably delayed relative to the instant of pulse transmission but alternatively a plurality of short duration sweep waveforms may be generated in succession, the beam of the C.R.O. being intensified during a selecable one of said sweeps. The endless carrier may comprise a continuous or perforated tape, a chain or toothed belt. As described separate electro-acoustic, e.g. magnetostrictive transducers are employed for transmission and reception. In one embodiment, Figs. 1a and b a record strip 1 is moved at a uniform velocity over a metal plate 2 and a recording stylus 5 is mounted on an endless tape 4 carried by a guide roller 6 and a roller 7 driven by an electric motor 11. Echo pulses from the receiving transducer 14 are applied through amplifier 15 to the C.R.O. 16 and through leads 18 to a bar 9 which contacts a blade 8 connected to the stylus 5. The transmitting transducer 13 is energized from a pulse generator 12 which is triggered when contacts 20 are closed by a cam 19 mounted on the tape 4 and the C.R.O. sweep generator 17 is triggered when contacts 22 are closed by a second cam 21 mounted on the tape 4, the two cams 19 and 21 being displaced transversely on the tape and the timing of the sweep trigger being controlled by sliding contacts 22 along a bar 23. In a modification (Fig. 3, not shown), the cams 19 and 21 actuating contacts 20 and 22 are mounted on the periphery of separate discs keyed to a common shaft geared to roller 6 and the contacts 22 are mounted on a disc which is rotatable about the shaft to vary the timing of the sweep trigger. If the gearing is such that contacts 20 and 22 are actuated twice during each complete circulation of the tape 4 then only echoes received during altimate recurrence periods are recorded by the stylus 5. In another embodiment (Fig. 2, not shown), a single cam mounted on the tape actuates a single set of contacts which triggers both the pulse generators 12 and an adjustable electronic time-delay whose output triggers the sweep generator 17 and in a modification (Fig. 4, not shown), the pulse generator and delay circuit are triggered by separate sets of contacts actuated by separate cams located on opposite end faces of the guide roller 6. Suitable electronic delay circuits are described with reference to Figs. 5, 6 and 7 (not shown), which are substantially identical with Figs. 2, 3 and 4 of Specification 726,964. In Fig. 4 (not shown), the adjustable delay may' be a clockwork device.