US2227045A

US2227045A - Television system

Info

Publication number: US2227045A
Application number: US142228A
Authority: US
Inventors: Urtel Rudolf
Original assignee: Telefunken AG
Current assignee: Telefunken AG
Priority date: 1936-05-12
Filing date: 1937-05-12
Publication date: 1940-12-31
Anticipated expiration: 1957-12-31
Also published as: FR48472E; NL48175C; DE758151C; GB495394A

Description

SEARCFWR 2 Sheets-Sheet. 2

BY Wg m SMSW ATTORNEY Patented Dec. 31, 1940 UNITED STATES SEARCH Fi 'lDl PATENT OFFICE TELEVISION SYSTEM Germany Application May 12, 1937, Serial No. 142,228

10 Claims.

This invention relates to television systems and particularly to the method of synchronizing remote pick-up transmitters which relay the video signals to a main television transmitter. This application is a continuation in part of my application entitled "Television system, Serial No. 70,906, which was filed March 26, 1936.

In the parent application a method of operating reporting or auxiliary television transmitters is described, in which, for instance, on a motor truck such a transmitter is mounted and assumed to be situated at the place of reporting, said transmitters sending their images to a stationary main transmitter. In this connection the use of cathode ray image analyzers is considered and a synchronizing of the latter in that the image transmission of the main transmitter is received at the place of reporting, and that the synchronizing impulses are filtered out and supplied to the analyzer.

This invention relates to the problem of operating such reporting transmitters ii the time of passage of the synchronizing impulses from the stationary main transmitter to the movable reporting transmitter and back can no longer be considered short as compared with the line duration of the television scanning. It is apparent in this case to take care by inserting artificial lines or phase delay networks at suitable places, that the difierent passage times are rendered equal to each other, said passages consisting on the one hand of the path from impulse generator of the main transmitter to reporting transmitter and back to main transmitter, on the other hand the path, impulse generator of the main transmitter to antenna of the main transmitter. In accordance with the invention in place of such phase displacement, only the line impulses filtered out at the place of the reporting transmitter are delayed by artificial lines and only after this is done, applied to the line deflection generator of the reporting scanner, such, that the line video signals are sent out by the main transmitter with a phase displacement of one or several total line periods relative to the impulses of the main transmitter having produced the scanning of this line content. The vertical impulses, i. e. those impulses which at distance transmission, without line interlacing, initiate the scanning of a new image, or those which at distance transmission with line interlacing produce the transmission of a new line sequence, will however not be delayed as may be pointed out already at this place.

Turning now to the drawing, my present invention will be described in detail. In the drawing s, Figs. 1 to 5 are graphs illustrative of the time displacements of the horizontal and vertical synchronizing impulses for difierent phase displacements,

Fig. 6 shows a block diagram of the main transmitter and only one of the remote pick-up or reporting transmitters, together with the circuits necessary to practice my invention, and

Fig. 7 shows a block diagram of my television system with a plurality of remote pick-up transmitters.

In the embodiment of the invention described inthe following, a phase displacement of the line picture signal content relative to the line impulses effecting the scanning of this line content, is assumed to be a single line period. In Figure 1 of the drawings, there is shown the time pattern of the synchronizing impulses such as are radiated into space by the main transmitter. Items Hi to H5 represent the line impulses, and item V is a vertical impulse. Owing to the finite travel time of the electrical waves, these impulses arrive at the reporting place in the manner shown in Figure 2. Each start of the impulse is displaced by the time a relative to the appertaining start of the impulse at the place of the main transmitter. Through suitable delay means care is taken that the line impulses (but not the vertical impulses) have the position as regards time such as shown in Figure 3, before being applied to the cathode ray scanner. Each line impulse, therefore, is artificially delayed by the time b, so that there corresponds with the impulse H1 in Figure 1, i. e. H1 in Fig. 2, the impulse H1" in Fig. 3. The time b is hereby to be chosen in such a manner that if added to the time 2a exactly a total line period will be obtained. In Figure 4 the brightness signals furnished by the cathode ray scanner are shown together with the impulses H1", etc. Also the impulse H3" obtained from the impulse H3, causes a line movement in the scanner. The following line however, will be released only when the impulse Hl" arrives at the scanner. The vertical impulse at the scanner however, has the same position as to time as the impulse V in Fig. 2, i. e. the same position as ahead of the delay arrangement of the reporting transmitter. Therefore, the second line beginning with the impulse Ha" will not be furnished at all by the scanner, if, as is customary, the scanning cathode ray is blocked during the vertical return movement. Owing to the finite travel time of the picture or video brightness signals on their way from the reporting transmitter to the stationary main transmitter, the image content and the line-and vertical impulses produced at the main transmitter have the position as to time as represented in Fig. 5. The image content which was released by the impulse H3" at the cathode ray scanner, will not be sent out at all at the side of the main transmitter. Furthermore, no image content will be transmitted by the main transmitter between the impulses H4 and H5. This condition is, however, without any detriment, since in view of the great number of lines per image such as is customary today, the suppression of one or even several lines at the end of a television image, and the appearance of one or several black image lines at the beginning of a television image will hardly be noticed at all. However, with the method proposed according to the invention, namely, to delay only the line impulses at the place of reporting before applying them to the scanner, the arrangements for taking care of the finite travel times of the signals are extremely simplified.

When introducing an artificial delay at the place of reporting, amounting to two or a greater number of line periods in conjunction with the time 2a, at the end of each image, two or a greater number of lines are suppressed, and therefore, the first two or more lines also appear at the received image without modulation of the brightness.

Fig. 6 shows a block diagram of the main transmitter and one reporting or remote pick-up transmitter. It is to be understood, however, that this is merely illustrative and that a plurality of such reporting transmitters may be used comprising the elements of 4 through 2| inclusive. When more than one such reporting transmitter is used, a switching panel is provided as shown in Fig. '7 so that the operator at the main transmitter may select either a locally generated picture signal or any one of the incoming signals from the recording transmitters.

As delay arrangement at the reporting transmitter, a special saw-tooth generator for instance, may be employed always initiated by the impulses Hi' etc. and releasing the impulse H'i when the saw tooth has reached a definite amplitude. Such an arrangement is described in application E 48,258 VIIIa/21a1, filed in Germany on April 23, 1936. Furthermore, in order to produce the impulses Hi" from the impulses Hi, also a multi-vibrator may be used, whereby the impulses H are applied to the one discharge path, and the impulses H" to the anode of the other discharge path. In choosing accordingly the time constants of the RC-members of this multivibrator, and constant sum of both time constants a desired time delay can be adjusted to. This is also still possible if the RIC-members are so dimensioned and/or connected with such bias potential that the initiation of the discharge in a discharge path of the multi-vibrator occurs on the non-linear part of the pattern of the grid potential.

Having described my invention, what I claim is:

1. A television system comprising a main transmitter, means to develop at the main transmitter signals representatives of an image to be transmitted, means for transmitting both line and frame synchronizing signals from said transmitter, a plurality of auxiliary transmitters, means to develop signals representative of an image to be transmitted at each of the auxiliary transmitters, means to receive the synchronizing energies at each of the auxiliary transmitters,

means to delay the line synchronizing energy with respect to the frame synchronizing energy, means to synchronize the plurality of auxiliary transmitters by the delayed line energy and the undelayed frame energy, means to transmit the signals developed at each of the plurality of transmitters to the main transmitter, and means at the main transmitter to select signals from among the signals developed by the auxiliary transmitters and the signals developed at the main transmitter signals for modulating the main transmitter.

2. A television system comprising a main transmitter, means to modulate the transmitterby both line and framesynchronizingsignals,an auxiliary television transmitter, means to receive the synchronizing signals from the main transmitter, means to separate the synchronizing signals from each other, means to delay the line synchronizing signals with respect to the frame synchronizing signals, means to actuate the auixiliary transmitter in accordance with the delayed line synchronizing signals and the frame signals, and means to transmit signals from the auxiliary transmitter to the main transmitter.

3. In a television system, wherein is provided a main transmitter and an auxiliary transmitter remote therefrom, the method of transmitting electro-optical representations of a scene from the auxiliary transmitter to the main transmitter, which comprises the steps of transmitting synchronizing energy of two diilerent types from the main transmitter, receiving the synchronizin energy at the auxiliary transmitter, altering the transmission time of one of the types of synchronizing energy with respect to the other of said types synchronizing the auxiliary transmitter by the received altered and unaltered synchronizing energy, transmitting energy representative of the object to be transmitted from the auxiliary transmitter to the main transmitter receiving the transmitted energy from the auxiliary transmitter at the main transmitter, and transmitting energy representative of the said object from the main transmitter.

4. In a television system, wherein is provided a main transmitter and a plurality of auxiliary transmitters remote therefrom, the method of transmitting electro-optical representations of a scene from the plurality of auxiliary transmitters to the main transmitter, which comprises the steps of transmitting synchronizing energy of two different types from the main transmitter, receiving the synchronizing energy at the plurality of auxiliary transmitters, altering the transmission time of one of the types of synchronizing energy with respect to the other of said types synchronizing the plurality of auxiliary transmitters by the received altered and unaltered synchronizing energy, transmitting energy representative of the object to be transmitted from the plurality of auxiliary transmitters to the main transmitter and retransmitting from the main transmitter energy transmitted from one of the plurality of auxiliary transmitters.

5. In a television system, wherein is provided a main transmitter and a. plurality of auxiliary transmitters remote therefrom, the method of transmitting electro-optical representations of a scene from the plurality of auxiliary transmitters to the main transmitter, which comprises the steps of transmitting two difierent sequences of synchronizing energy from the main transmitter, receiving the two sequences of synchronizing eniii] ergy at the plurality of auxiliary transmitters, delaying one of the received sequences of synchronizing energy with respect to the other of said two sequences synchronizing the plurality of auxiliary transmitters by the delayed and undelayed sequences of synchronizing energy, transmitting energy representative of the object to be be transmitted from the plurality of auxiliary transmitters to the main transmitter, receiving the transmitted energies at the main transmitter and selecting one of the received energies for actuating the main transmitter.

6. A television system comprising a main transmitter, means for transmitting two different sequences of synchronizing energy from said transmitter, a plurality of auxiliary transmitters, means to receive the transmitted two different sequences of synchronizing energy at each of the auxiliary transmitters, means to alter the transmission time of one of the two sequences of synchronizing energy with respect to the other of said sequences of synchronizing energy means to synchronize each of the auxiliary transmitters by the received altered and unaltered sequences of synchronizing energy, means to transmit signals of an image to be transmitted from each of the auxiliary transmitters to the main transmitters, means for receiving the transmitted signals and means to select one of the received energies for actuating the main transmitter.

7. A television system comprising a main transmitter, means for transmitting both line and frame synchronizing energy from said transmitter, an auxiliary transmitter, means to receive the synchronizing energies, means to delay the line synchronizing energy with respect to the frame synchronizing energy, means to synchronize the auxiliary transmitter by the delayed line energy, and the undelayed frame energy, and means to transmit signals representative of an image to be transmitted from the auxiliary transmitter to the main transmitter.

8. A television system comprising a main transmitter, means for transmitting both line and omn'cii iiUU frame synchronizing energy from said transmitter, an auxiliary transmitter, means to receive the synchronizing energies, means to delay the line synchronizing energy with respect to the frame synchronizing energy, means to synchro- 5 nize the auxiliary transmitter by the delayed line energy, and the undelayed frame energy, means to transmit signals representative of an image to be transmitted from the auxiliary transmitter to the main transmitter, and means to 10 transmit from the main transmitter both the signals from the auxiliary transmitter and the synchronizing energies.

9. A television system comprising a main transmitter, means for transmitting both line 15 and frame synchronizing energy from said transmitter, a plurality of auxiliary transmitters, means to receive the synchronizing energies, means to delay the line synchronizing energy with respect to the frame synchronizing energy, means to synchronize the plurality of auxiliary transmitters by the delayed line energy and the undelayed frame energy, means to transmit signals representative of an image to be transmitted from the plurality of auxiliary transmitters to 25 the main transmitter means to receive the signals transmitted from the auxiliary transmitters, and means to transmit from the main transmitter one of the received signals.

10. A television system comprising a main 30 transmitter, means for transmitting both line and frame synchronizing energy from said transmitter, a plurality of auxiliary transmitters, means to receive the synchronizing energies, means to delay the line synchronizing energy 35 with respect to the frame synchronizing energy, means to synchronize the plurality of auxiliary transmitters by the delayed line energy and the undelayed frame energy, means to select one of the energies transmitted from the plurality of auxiliary transmitters, and means to transmit from the main transmitter both the selected signals and the synchronizing energies.

RUDOlL-F UR'I'EL.