US2489253A - Multisignal recording system with signal identification - Google Patents

Description

nn Q W. L. ANDRE SIGNALIDENTIFICATION Filed June 18, 1946 Patented Nov. 29, 1949 @isnt IMI! MUUiiii MULTISIGNAL RECORDING SYSTEM WITH SIGNAL IDENTIFICATION Walter L. Andre, Dayton, Ohio Application June 18, 1946, Serial N0. 677,473

(Granted under the act of March 3, 1883, as amended April 30, 1928; 370 0. G. 757) 3 Claims.

The invention described herein may be manufactured and used by or for the Government for governmental purposes without payment to me of any royalty thereon.

This invention relates to multi-signal recorders and particularly to a remote recording system for continuously recording a number of varying electric signals which have been transmitted over a single channel transmitting medium using the share the time principle.

#Aibjetiiirthe invention is the provision of a remote multi-signal recorder having a fast signal sampling speed and requiring no channel separating or synchronizing equipment.

Another object of the invention is the provision of a recorder of the above type employing a single cath'odgmtuba in conjunction with photographic means for producing a continuous record of several signals.

A further object of the invention is the provision of means for marking the record, by a systematic interruption of signal transmission, soy that the several traces of the record may be identified.

The details of the invention will be explained in connection with the drawing in which Fig. 1 shows an embodiment of the recording system and Fig. 2 is a chart illustrating the operation of the recorder.

Referring to Fig. 1, the transmitting portion of the recording system comprises a rotary sequence switch 6 which has a revolving contact?.-

arrn 5 and a peripheral contact for each signal to be recorded plus one contact for a standard reference signal. In the embodiment shown. signals S2, S3, and S4 to be recorded are connected to contacts 2, 3 and 4 respectively and reference` signal Ris connected to contact I. A larger num-r.l ber of signals and a correspondingly larger number of contacts could be used if desired, however,l for simplicity only four are shown in the drawing The revolving contact 5 is connected through switch I to transmitting equipment 8. This equipment may be of any known type suitable to the transmission link used. For example, if a radio link is to be employed, 8 would be a radio transmitter.

A motor 9 is provided for driving rotating contact 5 through shaft I0. Cam II, for operating switch 1, is also driven from shaft Il] through gears I2 and I3. The ratio of gears I2 and I3 is such that cam II makes one revolution in somewhat less or greater time than contact 5, in accordance with the following equations:

S5:rotary speed of contact 5 S11=rotary speed of cam II N=number of signals to be recorded The above described mechanism connects the signals to the transmitting equipment in sequence through switch I which successively omits one signal from each sequence. For example, with the rotary Contact 5 on contact I and switch 1 open as shown in Fig. 1, and the gear ratio set for operation in accordance with Equation 2, the transmission of R is omitted after which signals S2, Ss, S4 and R are transmitted in succession until contact 5 reaches contact 2 at which time switch I will be open preventing transmission of S2. Likewise, in the next sequence, S3, S4, R and S2 are transmitted and then S3 is omitted. The order in which the signals are transmitted and the order in which they are omitted is fixed and is determined by the order in which the signal sources are wired to the sequence switch.

If the ratio of gears I2 and I3 is such that contact 5 rotates more slowly than cam II in accordance with Equation 1, successive omission 0f each signal also takes place in a manner similar to that described above except that, in this case, the sequence of omissions progresses around the switch 6 in a direction opposite to that of rotating contact 5 with the result that each signal is omitted more often than when operation is in accordance with Equation 2.

The receiving portion of the recording system comprises a cathode ray tube I4 having vertical and horizontal deecting plates as shown. Means including a source of voltage I5 and a potentiometer I6 are provided to adjust the horizontal ment 2| are applied to the vertical deflecting plates across resistor I9 by means of lead 20. The receiving equipment may be of any known type capable of converting the received energy into voltages proportional to the original signals to be recorded and of amplifying these voltages to values sufcient to operate the cathode ray tube. The indication on the screen of the cathode ray tube is in the form of a series of spots along a vertical line, the spot at the bottom indicating the zero position of the beam and the displacement of the other spots from the zero position indicating the instantaneous values of the signals to be recorded, including the reference signal.

In order to form a continuous record, lens 23 is utilized to produce an image of the uorescent screen of the cathode ray tube on the photosensitive lm or paper 22, which is caused to move slowly at constant speed by means of motor 24 and driving mechanism 25. In order to place a time reference on the record, a flashing light source 26 controlled by timing means 21 is utilized to mark the record at equal intervals of time. The photosensitive material 22, lens 23, marking light 25 and the screen of the cathode ray tube are of course enclosed in a light-proof boX. It is not essential that the lens be used as the photosensitive material may be placed directly against the screen of the cathode ray tube.

The chart shown in Fig. 2 represents the ty-pe of record produced on the photosensitive film or paper by the apparatus described in Fig. 1. The chart is drawn for a system in which the sequence switch has four contacts, with three variable and one reference signal connected thereto as shown in Fig. 1, and in which operation is in accordance with Equation 2 or, in other words, in which contact makes 1.25 revolutions for each revolution of cam II. The distance betweenthe vertical solid lines on the chart represents the time required for contact 5 to make one complete revolution and the distance between vertical dotted lines represents the time required for rotary contact 5 to move from the center of one outer contact to the center of the succeeding outer contact. The short dashes in this figure represent the trace made on the photosensitive paper by the uorescent spot on the cathode-ray tube screen While the moving contact 5 is passing over any one of stationary contacts I throughl 4 or, in the case of the short dashes at the zero beam position, when the contact 5 is moving between adjacent stationary contacts. The longer dashes in the zero beam position line are caused by switch 'I being open when movable contact 5 is on the corresponding stationary contact thus causing the beam to remain in its zero position from the time Contact 5 breaks with one of the stationary contacts until it makes with the second succeeding stationary contact. The path followed by the electron beam, or the resulting fluorescent spot on the cathode-ray tube, is shown for two revolutions of sequence switch 6 by the light solid lines connecting the various dashes.

The chart'starts with the sequence switch at the position shown in Fig. 1. With rotary contact 5 on contact I and switch 'I open, the beam is at its zero position as shown by the dash at the first position on the chart and there is therefore a break in the trace of reference signal R at this point. Movement of contact 5 to contact 2 causes switch 'I to close and the beam to travel upward to a point on the contact #2 dotted line determined by the value of Sz at that instant. Likewise movement of Contact 5 from contact 2 to contact 3 causes the beam to return to its zero position and then to a position on the contact #3 dotted line determined by the value of S3 at that instant. This process continues until contact 5 returns to contact I after which the beam returns to its zero position until contact 5 reaches contact 3 due to the fact that switch 'I is open while contact 5 is passing over contact 2. This omission causes a break in the trace for signal S2. Similarly successive breaks are caused to occur in the remaining signals S3 and S4. This process continues to repeat itself causing a series of successive breaks in each trace as illustrated in Fig. 2. The chart therefore consist of four traces, one for each of signals S2, S3, S4 and R, with each trace composed of a series of groups of four dashes. In the figure a light line has been drawn through the dashes of each trace to form a continuous curve as may be done in the evaluation of an actual record.

In order to identify the several traces, it is necessary to determine when the break in a particular trace occurs with respect to the break in the reference trace R. For example, in Fig. 2, the break in curve C is the first to occur after a break in R. Curve C must therefore represent S2 since the contact for S2 follows that for R or the sequence switch. Likewise, it follows that curve A represents S3 and curve B represents S4. Evaluation of the traces is done by comparing the height of the trace above the zero line with the height of the known reference trace R above the zero line. The equally spaced marks below the zero line in Fig. 2 represent equal intervals of time and are produced by timing light 25, Fig. 1.

I claim:

1. In a remote recording system of the type in which a plurality of signals one of which is a reference signal are transmitted successively over a single channel transmission means and recorded at the receiving end as a plurality of traces along a common time axis, an improved transmitter comprising rst means for applying said signals to said single channel transmission means in a recurring xed sequence and second means interposed between said rst means and said single channel transmission means and synchronized With said first means for periodically blocking the application of said signals to said single channel transmission means one at a time and in a predetermined progressive sequence with respect I to the reference signal, whereby identifying breaks are produced in the recorded traces.

2. In a remote recording system of the type in which a plurality of signals are transmitted successively over a single channel transmission means and recorded at the receiving end as a plurality of traces along a common time axis, an improved transmitter comprising a cyclic switch containing a plurality of stationary contacts and a cooperating revolving contact, said stationary contacts being equal in number to the number of signals to be recorded and being positioned with equal separation around the circumference of a circle centered on said revolving contact, means for rotating said revolving contact at constant speed, means for applying each of said signals to be recorded to an individual one of said stationary contacts, a cam operated switch connected between said revolving contact and said single channel transmission means, and gear means between said cam and said revolving contact rotating means for rotating said cam once for each revolutions of said revolving contact where N is the number of signals to be recorded, the angular extent of Said cam being sumcient to hold said cam operated switch open for a period of time exceeding the time required for said revolving 10 contact to pass over a. stationary contact.

3. In a remote recording system of the type in which a plurality of signals are transmitted successively over a single channel transmission means and recorded at the receiving end as a"15 plurality of traces along a common time axis.^ an improved transmitter comprising first means for applying said signals to said single channel transmission means in succession and second means interposed between said iirst means and, 20

said single channel transmission means and syri-` chronized with said rst means for operating after each N consecutive applications of each one of said signals to said single channel transmission means to block the next application of that signal thereto, N being the number of signals to be recorded.

WALTER L. ANDRE.

REFERENCES CITED The following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 2,165,892 Green July 11, 1939 2,265,216 Wolf Dec. 9, 1941 2,307,505 Heinmets Jan. 5, 1943 2,403,890 Johnson July 9, 1946 2,410,821 Hillman Nov. 12, 1946 2,414,221 Bristol Jan. 14, 1947

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