US2189119A - Signal measuring system - Google Patents

Description

Feb. 6, 1940.

J. J. SCHLUTER SIGNAL MEASURING SYSTEM Filqd Sept. 8, 1938 INVENTOR J /m (Isa/km ATTORNEY Patented Feb. 6, 1940 mire, STATES PATENT O EN 4Claims. (cine-475.1)

. i This invention "relates'to electrical signaling systems. More particularly this invention relates to'electrical systems for indicating to the speaker or operator the level of speech or other currents.

'5 When speech or other energy is impressed upon the telephone transmitter of a telephone sub.- .scribers set'it is :difiicu'lt and often impossible for thespeaker or operator to determine whether the 'levelof the impressed energy issufiicient for io good' transmission. :Two factors largely determine whether or not theimpressed energy is sufficient for good transmission to the distant end *of the circuit. These two factors are (l) the dis H tance between the speakers lips and the teleili phonetransmitter and"(2) the tone or level of .the voice used... 1 1 i 1 1 .Speechforother' energy of loud-tone or high level need notbe impressed as closely to the telephone transmitter as energy of lower tone or Q level to'producethe same electrical effects. A :very low toneor signal level will necessarily have to be impressed quite closely to the telephone transmitter to beeifectively transmitted to the distant station. If a low tone is produced a substantial distance from the. transmitter it may of course be so attenuated bythe circuit as to be. practically T inaudible at the distant end. The determination of the proper tone or level and/or the proper 'distance between the speakers lips and the. telephone transmitter is" of importance to. the efficient use of signaling systems employed for telephone transmission.

*It is therefore one'of the objects of this invention to indicate instantly to the subscriberor operator the approximate level of speech or other signal energy impressed upon atelephone transmitter which, for: example, may be part of a telephone 'subscribers set. I It is a further object of this invention to in- 40 dicate instantly to the speaker or operator whether the level of speech or other signal energy is sufficient for good transmission.

It is a still further object of this invention to indicateapproiiimatelywhat the level of the energy impressed upon the transmitter may be when thesource of the energy is positioned at different distances from the transmitter.

These. and other objects and features of the which may bea part of a telephone subsc'rib'ers set. This transmitter may be connected to the primary windingof a transformer T1, the connection being'established through a double-pole -single-throw switch S1 and through the upper 5' blade of 'a double-pole. single-throw switch S2.

The secondary winding of the'transformer T1 7 is connectedas part of the grid circuit of an amplifier. tube V1 which will be referred to again hereinafter. I 110 'Anelectrical buzzer Y of any Well-knowntype,

having a source ofxcurrent for its operation as .shown, may be positioned directly in-front of the transmitter TR so that sounds produced by the I buzzer will become impressed upon the transmit l5 ter TR and then transmitted tothe grid circuit of the amplifier tube V1. It will hence be apparent that upon closureof the switches Srand 'Sz, voiceenergy or'the buzzer energy may beimpressed'nponthe transmitter TR ahdthen am- 20 'plified, the amplifiedenergy being utilized for obtaining, an indicationof thelevel'of the impressed energy as will be described more. fully hereinafter. l 1.

- The apparatus' for determining the level of the 25 energy impressed upon the grid circuit of the tube V1 includesa' generator of alternating current designated G which may be a, -cycle alternatingcurrent generator'of 100 or 115 volts which may be connected by i a double-pole single-throw switch Syand through the lower blade of a similar double-pole single-throw switch S4 to the primary windings of transformers T2 and T3, these primary windings being connected in parallel re lationship. When both of the switches S3 and S4 are closed, the lamp L0 will be lighted and The secondary winding. of the transformerTa 40 isconnected to the filament or heater of the tube 'V1as well'as to the filament of the tube V2, the

two filaments being aranged in parallel relationship. The secondary winding of the transformer Ta will be utilizedtoheat the filaments of lamps L1, Lz'or Ls'ina manner to be described more. fully hereinafter. I i l l A Theamplifier tube V1 is of the heater type, the cathode of which is in circuit with a resistor 210,;

the secondary windingiof the transformer T1 and :50 the grid of the tube" V1, the latter circuit being commonly known as the grid circuit ofthe tube.

The plate voltage of the tube V1 is supplied by battery B1 through the primary winding of the transformer Tti The energy amplified by'the 66 tube V1 impressed upon the grid of tube V2 which is of the rectifying type, the grid circuit of the latter tube including a battery B2 which produces the voltage for properly biasing the grid electrode of the tube with respect to its cathode. The plate circuit of the tube V2 includes the oathode of'the tube, both halves of the secondary winding of transformer T2, the conductor common to these two halvesof the secondary winding, the milliammeter MA, the resistors Z1, Z2, and Z3, the battery B1 and the resistor .20. The battery B1 of this series circuit is employed to supply the anode voltage for the rectifying tube V2. The flow of anode current through the series circuit just described will be utilized for the operation of various relays as will now be described.

The resistors Z1, Z2 and Z3 are shunted by the windings of relays R1, R3 and R3, respectively.-

These resistors may be of different magnitudes and the relays will be so adjusted that they will operate at different values of current flowing through the series anode circuit of tube V2, above described If the current flowing in this series circuit is of very low value it may be sufficient to produce a voltage across the resistor Z1 which is ample to operate the relay R1. But this small current will produce voltages across resistors Z2 and Z3 which will be insufiicient to operate the relays R2 and R3. If a greater current is rectifled by the tube V2, the voltage impressed across the resistor Z2 may be sufficient to operate the relay R2 and therefore relay R2 will be operated. Inasmuch as the same current traverses the resistor Z1, the relay R1 will be maintained in operation. If a still greater current flows through the anode circuit of tube V2, the voltage established across resistors Z1, Z2, and Z2 may be sufficiently large so as to cause the operation. of allthree relays R1, R2 and R3 and of course relay R3 will then operate while relays R1 and R2 will be maintained in their operated condition.

The operation of the relay R1 will in turn operate the relay R'1, the circuit of the winding of relay R'1 including the battery B1, the resistor Z1 the winding of relay R'1, the armature and contact of relay R1 and the upper blade of switch arm of switch. S5.

S4. Similarly the operation of relay R2 will cause the operation of relay R'2, current then flowing over the circuit including battery B1, resistor Z12, the winding of relay R'2, the armature and contact of relay R2, and the upper blade of switch S1. Similarly the operation of relay R2 will cause the operation of relay R: as will be clearly understood.

By opening switches S1 and S2 and closing switches S3 and S4 the operator may light any one of the, lamps L1, L2 or L3 which are associated with the relays R'1, R'2 and R'2, respectively. When the operator moves the rotary switch S5 to its contact I, the lamp L1 will be lighted, the circuit for lamp L1 including the secondary windingof transformer T3, the movable arm of switch S5 and lamp L1. By moving the arm of switch S5 to its contact 2, the lamp L1 will be disconnected from the secondary winding of transformer T3 and extinguished and lamp L2 will be connected to that winding through the Consequently the lamp L2 will be illuminated. By further moving the arm of switch S5 to its contact 3, the lamp L2 will be extinguished and the lamp L3 will then be illuminated. The lamps L1, L2 and L3 are preferably colored lamps, the lamp L1 for example being colored red, the lamp L2 amber and the lamp Ls green. These three lamps will be used to indicate instantly to the speaker or operator what the approximate level of the energy impressed upon the transmitter TR may be, the lamp L1 indicating a low level of impressed energy, the lamp L2 a higher level and the lamp L3 a still higher level. Of course more than three lamps may be employed in this circuit arrangement as will be obvious to those skilled in the art.

Suppose now that the switches S1 and S2 are both closed so as to connect the transmitter TR to the primary winding of the transformer T1 and suppose also that the buzzer Y is unoperated and that no speech or other energy is impressed upon the transmitter TR. Under these circumstances the current fiowing in the anode circuit of the rectifying tube V2 and through the resistors Z1, Z2 and Z3 will be so low as to be inadequate to operate relays R1, R2 and R3. The relays R'1, R'2 and R's will also be unoperated and if the movable arm of switch S5 is on its contact 0, none of the lamps L1, L2 or L3 will be illuminated. If now the circuit of buzzer Y is completed and the buzzer is held approximately three feet from the transmitterTR, the energy impressed'upon the transmitter and amplified by tube V1 and rectified for tube V2 will be of rather low value. This small amount of energy will, however produce a voltage across resistor Z sufiicient to cause the operation of relay R1. The operation of relay R1 will in turn operate the relay of R'1 which in turn will cause the lamp L1 tobe lit. The circuit of lamp L1 will include the secondary Winding of transformer T3, the armature and back contact of relay R'3, the armature and back contact of relay R'2, the armature and make contact of relay R'1 and lamp L1. The lamps L2 and L3 will of course remain unlit. The lamp L1, which is painted red as suggested above, will indicate to the operator that the level of energy impressed upon the transmitter TR is insufficient for good signal transmission over the telephone circuit, for example, to which the transmitter TR may be connected.

If now the buzzer Y is moved closer to the transmitter TR the amplitude of the current flowing through the anode circuit of the tube V2 wil be such as to produce a sufficient voltage across resistor Z2 to operate the relay R2. The operation of relay R2 will then cause the operation of relay R'2 and this in turn will cause the lamp L2 to be lit. The circuit of lamp L2 will include the secondary winding of transformer T3, the armature and back contact of relay R'2, the armature and make contact of relay R'2 and the lamp L2. By opening the circuit of the back contact of the armature of relay R'2, the lamp L1 will become extinguished. The illumination of the lamp L2 will, however, indicate to the operator that the level of energy impressed upon the transmitter TR is better than before but this level of energy will still be insuflicient for good signal transmission.

If now the buzzer Y is moved still closer to the transmitter TR, i. e., the buzzer is now positioned in approximately the normal position of a talkers lips close to the transmitter TR, the magnitude of the rectified current flowing through the resistor Z3 will produce such a voltage across its terminals as will be sufficient to operate the relay R3. The operation of the relay R3 will in turn operate the relay R: and this in turn will illuminate the green lamp, L2. The circuit of the lamp L3 will include the secondary winding of the transformer T3 and the armature and make contact of relayRa However, upon the opening of the back contact of relay -R3,-it will be clear that the lamp L2 will become extinguished The illumination of the green lamp L3 will indicate to the operator that the level of the energy impress"ed upon the'transmitter I'R' is sufiici'ent for good*transmission. This position of the buzzer Y with respect to the transmitter TR may now approximate that whicha speakers lips should occupy for good transmission. If the buzzer Ybe now moved away from the transmitter TR a sumcientdistance the relay Ra will release and this in turn will cause the relay 'Bl'sto release.

back contact of relay R's and the armature and make contact of relay R'2.

If the buzzer be now moved still further away from the transmitter TR the relays R2 and R2 will become released and the lamp L2 extinguished. But if the flow of current through the resistor Z1 is sufficient to maintain relay R1 operated relay R'1 will also remain operated and then the lamp L1 will become reilluminated.

Thus it will be clear that as energy similar to that obtained from. the buzzer Y is impressed upon the transmitter TR, one of lamps L1, L2 or L3 will be illuminated and remain illuminated depending upon the level of energy so impressed upon the transmitter. As the level of energy rises from a very low value to a much higher sively operated in sequence.

\ energy becomes reduced from a very large value to a very small value the lamps L3, L2 and L1 will i become progressively illuminated in sequence.

Each of the lamps will indicate within reasonable limits the approximate level of the energy conveyed to the transmitter TR.

If the circuit of the buzzer Y be now opened and speech be impressed'upon the transmitter TR the level of the currents flowing through the anode circuit of tube V2 and through resistors R1 and R2 and R3 will cause the lamps L L2 and L3 to become illuminated according to the magnitude of the speech currents so impressed, as will be clear from the description given hereinabove. A loud tone produced, for example, quite close to the transmitter TR will cause the lamp L3 to become illuminated and then lamp L3 will remain illuminated if this rather loud tone persists. If the tone be produced somewhat more distantly from the transmitter then the lamp Lz-the amber lampwill be illuminated and the lamp L2 will remain illuminated if this tone persists at approximately the same level. If the tone be very soft or very distant from the transmitter TR then of course the lamp L1-the red lamp will be lighted. If the tone be unsteady the lamps will flash on and off according. to the durations of the tone pulses, the frequency of the flashes depending of course upon the nature of the words or phases used, as will be understood by those skilled in the art. Yet the average light impression obtained from the various lamps, that is, the average time during which the green lamp L3 will be lit or the amber lamp L2 will be lit, etc., will determine whether this speech is good or only fair or very poor. l

The tone impressed upon the transmitter TR tion ofvacuum tube amplifier circuits.

described causes a variablecurrent to flow through theprimary winding of the transmitter T1, the normal carrier current being supplied bybattery B1. This variable modulated current produces an alternating current voltageinthe secondary winding 'oftransformer T1 which is applied to the grid circuit of the amplifiertube V1. The plate current of the tube V1 is then caused to vary due to the alternating current voltage applied to the grid according to the customary ac- The amplified alternatin current voltage transmitted tothe secondary winding of transformer T; will .then be applied to grid of the rectifying Jtube V2. The grid or the latter'tube is biased negativelywith respect to its cathode: and hence will pass-plate current only during the positive 'grid swings, and then only in accordance with the grid-voltage plate-current characteristic curve of this tube. The rectified current of tube V2 will then flow through the resistors Z1, Z2 and Z3 as well as through the milliammeter MA and the voltages produced at the terminals of the latter resistors will be employed to operate one or more of the relays R1, R2 and R3 as already explained.

It will be apparent that the arrangement illustrated in the drawing may be employed to visually indicate the proper and improper use of a telephone transmitter. The signals will especially indicate the proper distances; required between thelips of the speaker and the telephone transmitter TR and/or the proper tone level for good transmission.

The apparatus described in this application may be readily employed for various purposes. The apparatus may be used for example, to train the announcers and artists in broadcasting studios to talk or sing into the microphone with the proper volume or voice level.

While this invention has been shown and in certain particular embodiments merely for the purpose of illustration, it will be understood that the general principles of this, invention may be applied to other and widely varied organizations without departing from the spirit of the invention and the scope of the appended claims.

, What is claimed is:

l The combination of a telephone transmit- ,ter upon which speech currents may be impressed, an amplifier coupled to said transmitter,

a detector coupled to said amplifier, a plurality the corresponding indicator, and means for successively operating a predetermined number of said relays, the number of relays operated corresponding to the amount of energy in the various frequency components impressed upon said transmitter.

2. Apparatus for indicating instantly the amount of energy impressed upon a telephone transmitter, comprising a detector for detecting substantially all of the components of the impressed energy, and means responsive to the detected energy for indicating the approximate magnitude of the detected energy, said indicattude of the detected energy, and signal devices controlled by said relays.

. 3. A system for instantly indicating to a speaker the amount of energy impressed upon a telephone transmitter, comprising means for detecting the. energy impressed on the telephone transmitter, a plurality of impedances connected in series with said detecting means, first and second groups of relays, the windings of the relays of the first group respectively shunting said impedances, the relays of the second group being operated in response to the corresponding relays of the first group, means for successively operating a predetermined number of the relays of the first group, the number of relays operated corresponding to the amount of energy impressed upon the telephone transmitter, and indicating means controlled by the relays of the second group.

4. A system for instantly indicating the amount of energy impressed upon a telephone transmitter, comprising means for detecting the energy in substantially all of the components impressed upon said telephone transmitter, and means responsive to the detected current for indicating the amount of detected current, said indicating means including a plurality of impedances connected in series with each other and with said detecting means, the detected current flowing through said series impedances, a plurality'of relays, the windings of which respectively shunt said impedances, said relays operating successively, the number of relays operated correspondingto the magnitude of the detected current, and indicating means controlled by said relays.

- 1 JOHN J. SCHLUTER.

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