DK149671B

DK149671B - ALARM SIGNAL GENERATOR FEEDING A PRESSURE SPEAKER SPEAKER

Info

Publication number: DK149671B
Application number: DK388480AA
Authority: DK
Inventors: Wolfgang Esser
Original assignee: Wandel & Goltermann
Priority date: 1979-09-13
Filing date: 1980-09-12
Publication date: 1986-09-01
Also published as: ATE8081T1; EP0025537A1; DK388480A; DE2936981C2; DE2936981A1; FI802589A; EP0025537B1; NO802696L; NO149367B; NO149367C

Abstract

1. Warning signal generator for supplying a signal to a compression driver projector horn whose sound propagation range lies above a preset fundamental frequency of a warning signal to be propagated by a compression driver projection horn loudspeaker, and the aforementioned warning signal contains a great many components of harmonics that occur in the sound projection range of the compression driver projection horn loudspeaker, characterized by the warning signal is a composite signal formed to be a square wave signal at constant amplitude and comprising a first square wave signal (4f) at the frequency of the fourth harmonic and a second square wave signal (2f) at the frequency of the second harmonic, whereby the fundamental frequency (f) is the changeover switching frequency used for switching between the first and second (4f, 2f) square wave signals, so that at the output (A) of the warning signal generator, the signal alternates at the same periodic rate of change of the fundamental frequency (f), and during each first half-period of the fundamental frequency, the first square wave signal appears and during each second half-period of the fundamental frequency, the second square wave signal appears, with the consequence that the warning signal appears as the composite of the two (Fig. 2d).

Description

143671143671

Den foreliggende opfindelse angår en alarmsignalgenerator af den i krav 1·s indledning angivne art.The present invention relates to an alarm signal generator of the kind set forth in the preamble of claim 1.

Til udstråling af alarmsignaler benyttes ofte trykkammerhøjttalere, som har af deres konstruktion betingede udstrålingsegenskaber. Eksempelvis kan membranstørrelsen være begrænset af mulighederne for at ind- eller påbygge højttaleren på eksempelvis et køretøj. Sådanne trykkammerhøjttalere benyttes eksempelvis på ambulancer og politiets udrykningskøretøjer.For radiating alarm signals, pressure chamber speakers are often used which have radiation characteristics conditional on their design. For example, the diaphragm size may be limited by the ability to mount or mount the speaker on, for example, a vehicle. Such pressure chamber speakers are used, for example, on ambulances and police emergency vehicles.

Alarmsignalers grundfrekvenser er ved norm fastlagt i frekvensområdet 360-630 Hz. Da disse grundfrekvenser ligger uden for den anvendte trykkammerhøjttalers overføringsområde, kan signalerne kun udstråles med stærkt formindsket virkningsgrad. En høj lydstyrke ved udstråling af disse grundfrekvenser kan kun opnås ved hjælp af en kraftig forstærkning.The basic frequencies of alarm signals are determined by norm in the frequency range 360-630 Hz. Since these fundamental frequencies are outside the transmission range of the pressure chamber speaker, the signals can only be radiated with greatly diminished efficiency. A high volume of radiation at these fundamental frequencies can only be achieved by a powerful amplification.

Man kan udnytte den omstændighed, at det menneskelige øre ikke kan opfatte forhåndenværende differenstoner i en toneblanding. Vælger man en toneblanding med svingninger, hvis frekvenser har samme indbyrdes afstande og ligger i det optimale overføringsområde for en toneblandingen udstrålende trykkammerhøjttaler, vil tilhøreren have det subjektive indtryk, at øret påtrykkes differenstonen med stor amplitude.One can take advantage of the fact that the human ear cannot perceive available differential tones in a tone mix. If one chooses a tone mix with oscillations whose frequencies have the same spacing and lies in the optimal transmission range for a tone mixing radiating pressure chamber speaker, the listener will have the subjective impression that the ear is applied to the differential tone with high amplitude.

Fra DE-AS 21 04 954 kendes således en akustisk signalgiver til køretøjer, hvor et i det optimale overføringsområde for en elektromekanisk lydstråler liggende modulationssignal frembringes, ved at man lader en grundsvingning, som er frembragt af en første generator og har det ønskede signals frekvens, eksempelvis 400 Hz, modulere en overtonesvingning, der er frembragt af en anden generator og har en frekvens på eksempelvis 2 kHz. Herved udstråles signaler med frekvenserne 1,6 kHz, 2 kHz og 2,4 kHz, medens øret opfatter differenssignalet på 400 Hz.Thus, from DE-AS 21 04 954 an acoustic signal generator is known for vehicles in which a modulation signal located in the optimum transmission range of an electromechanical sound beam is produced by charging a fundamental oscillation produced by a first generator and having the desired signal frequency. for example, 400 Hz, modulate an overtone vibration produced by another generator and has a frequency of, for example, 2 kHz. This radiates signals at frequencies 1.6 kHz, 2 kHz and 2.4 kHz, while the ear perceives the 400 Hz differential signal.

Fra FR-PS 2.333.314 kendes en lignende opstilling, hvor imidlertid de to signaler, som skal blandes, frembringes af kun en generator i forbindelse med en frekvensdeler eller frekvensdobler. Der arbejdes med firkantsignaler, og modu-latoren leverer en firkantspænding med alternerende amplitude (soidsværdifaktor 1), som ikke er egnet til at drive en forstærker.From FR-PS 2,333,314 a similar arrangement is known, however, the two signals to be mixed are generated by only one generator in connection with a frequency divider or frequency doubler. Square signals are used and the modulator delivers a square voltage of alternating amplitude (soils value factor 1) which is not suitable for operating an amplifier.

2 use 712 use 71

Fra DE-AS 25 18 708 kendes et mobilt alarmsignalanlæg med en højttaler, en forstærker og en alarmsignalgenerator. Generatoren afgiver til forstærkeren en bipolær firkantspænding med en særlig kurveform, der indeholder strømløse afsnit. Der er derfor tale om et særlig stort indhold af grundtonen, hvilket ved anvendelse af højttalere med et over denne grundtone liggende overføringsområde ikke kan medføre et optimalt lydtryk.DE-AS 25 18 708 discloses a mobile alarm signal system with a loudspeaker, an amplifier and an alarm signal generator. The generator delivers to the amplifier a bipolar square voltage with a special waveform containing powerless sections. Therefore, there is a particularly high content of the root tone, which, when using speakers with a transmission range above this root tone, can not cause an optimal sound pressure.

Fra DE-PS 2.104.954 og DE-PS 2.554.940 kendes akustiske signalgivere, hvor alarmsignalet frembringes af en overtonegenerator, der tastes ("moduleres") med alarmsignalets grundbølge. Tastningen bevirkes ved hjælp af en anden (grundtone-) generator henholdsvis af en til overtonegeneratoren forbundet tællerkobling. Tastningen medfører, at der i visse dele af grundtoneperioden ikke optræder nogen signalamplitude, således at spidsværdifaktoren } 1.From DE-PS 2,104,954 and DE-PS 2,554,940 acoustic signal generators are known, in which the alarm signal is generated by a harmonic generator which is keyed ("modulated") with the basic wave of the alarm signal. The keying is effected by means of a second (root tone) generator or a counter coupling connected to the harmonic generator, respectively. The test results in no signal amplitude appearing in certain parts of the root tone period, so that the peak value factor} 1.

Formålet med den foreliggende opfindelse er at anvise en generator for et alarmsignal, hvilken generator kræver mindst mulig komponentopbud og især ingen modulator, og som frembringer et alarmsignal med spidsværdifaktoren 1.The object of the present invention is to provide an alarm signal generator which requires the least possible component range and in particular no modulator, and which generates an alarm signal with the peak value factor 1.

Dette opnås ifølge opfindelsen ved den i krav 1 anviste konstruktion.This is achieved according to the invention by the construction of claim 1.

Herved opnås en enkel generator for et firkantformet alarmsignal uden grundtoneandele med spidsværdifaktoren 1, og som i det væsentlige indeholder 2den, 3die og 4de harmoniske og dog giver det subjektive indtryk, at øret modtager grundfrekvensen. Forstærkerens ydelse kan især holdes lav, når for det første de af en trykkammerhøjttaler udsendte overtoner ligger i højttalerens overføringsområde, og for det andet disse overtoner samtidig ligger i området for ørets maksimale følsomhed.Hereby, a simple generator for a square-shaped alarm signal without root tones is obtained with the peak value factor 1, which essentially contains the 2nd, 3rd and 4th harmonics and yet gives the subjective impression that the ear receives the fundamental frequency. In particular, the amplifier's performance can be kept low when, firstly, the harmonics emitted by a pressure chamber speaker are in the speaker's transmission range, and secondly, these harmonics are in the range of maximum sensitivity of the ear.

Opfindelsen skal i det følgende forklares nærmere i forbindelse med tegningen, hvor fig. 1 viser et blokdiagram for en alarmsignalgenerator ifølge opfindelsen, og fig. 2 forskellige i generatoren optrædende signaler.BRIEF DESCRIPTION OF THE DRAWINGS The invention will now be explained in more detail in connection with the drawing, in which 1 is a block diagram of an alarm signal generator according to the invention; and FIG. 2 different signals appearing in the generator.

Den i fig. 1 viste alarmsignalgenerator består af en firkantgenerator 1, en første frekvensdeler 2, en anden 149671 3 frekvensdeler 3» en omskifter 4 og en signalforstærker 5. Signalforstærkeren 5 føder en trykkammerhøjttaler 6, der er forbundet til arlarmsignalgeneratorens udgang A.The FIG. 1 alarm signal generator consists of a square generator 1, a first frequency divider 2, a second frequency divider 3 »a switch 4 and a signal amplifier 5. The signal amplifier 5 feeds a pressure chamber speaker 6 connected to the output A. of the alarm signal signal generator A.

Firkantgeneratoren 1 frembringer et første firkantsignal 4f, hvis frekvens er fire gange så stor som frekvensen af alarmsignalets grundtone. Firkantgeneratorens 1 udgang er forbundet til indgangen på den første frekvensdeler 2 og til en kontakt u på omskifteren 4. Den første frekvensdeler 2 neddeler signalet 4f fra firkantgeneratoren i forholdet 2:1 og afgiver således et andet firkantsignal 2f, hvis frekvens er to gange så stor som frekvensen af alarmsignalets grundtone. Dette andet firkantsignal 2f påtrykkes indgangen på den anden frekvensdeler 3 og en anden kontakt v på omskifteren 4.The square generator 1 generates a first square signal 4f, the frequency of which is four times the frequency of the alarm tone root. The output of the square generator 1 is connected to the input of the first frequency divider 2 and to a contact u of the switch 4. The first frequency divider 2 divides the signal 4f from the square generator in the ratio 2: 1 and thus emits a second square signal 2f, the frequency of which is twice as large. such as the frequency of the alarm tone root. This second square signal 2f is applied to the input of the second frequency divider 3 and a second switch v of the switch 4.

Også den anden frekvensdeler 3 neddeler det påtrykte signal i forholdet 2:1 og afgiver således et tredje firkantsignal f med grundtonens frekvens. Dette tredje firkantsignal f benyttes som styresignal for omskifteren 4 således at dennes kontaktarm med grundtonefrekvensen f svinger mellem de to kontakter u og v. Fra omskifteren 4 påtrykkes signalforstærkeren 5 i takt med grundfrekvensen f afvekslende det første firkantsignal 4f og det andet firkantsignal 2f.Also, the second frequency divider 3 divides the applied signal in a ratio of 2: 1 and thus emits a third square signal f with the frequency of the fundamental tone. This third square signal f is used as the control signal for the switch 4 so that its contact arm with the fundamental tone frequency f oscillates between the two contacts u and v. From the switch 4, the signal amplifier 5 is applied in step with the fundamental frequency f alternating the first square signal 4f and the second square signal 2f.

Fig. 2a, 2b og 2c viser det første, det andet henholdsvis det tredje firkantsignal 4f, 2f og f. Fig. 2d viser det signal, som påtrykkes signalforstærkerens 5 indgang, altså det signal, som efter forstærkning udstråles af højttaleren 6 som alarmsignal.FIG. 2a, 2b and 2c show the first, second and third square signals 4f, 2f and f, respectively. 2d shows the signal which is applied to the input of the signal amplifier 5, that is, the signal which, after amplification, is emitted by the speaker 6 as an alarm signal.

På grund af alarmsignalets firkantform (fig. 2d) forekommer der overtoner som ligger i trykkammerhøjttalerens overføringsområde. Alarmsignalet tilføres signalforstærkeren som et alternerende signal, dvs. et signal som skiftevis er positivtog negativt Under den samlede periodevarighed kan der således fra signalforstærkeren 5 afgives energi, hvorhos en jævnstrømsmagnetisering i forstærkerens udgangstransformer 7 skal undgås. Ved omskiftningen med grundtonens frekvens mellem det første firkantsignal 4f og 149671 4 det andet firkantsignal 2f fremkommer et signal som indeholder en stor andel af anden, tredje og fjerde harmoniske og en ringe andel af grundtonen. Disse overtoner ligger i højttalerens overføringsområde når grundtonen ligger i området 3-800 Hz.Due to the square shape of the alarm signal (Fig. 2d), overtones occur in the transmission range of the pressure chamber speaker. The alarm signal is applied to the signal amplifier as an alternating signal, ie. a signal which alternately is positive train negative During the total period duration, energy can therefore be emitted from the signal amplifier 5, whereby a direct current magnetization in the amplifier output transformers 7 is to be avoided. When switching with the frequency of the root tone between the first square signal 4f and 149671 4 the second square signal 2f, a signal appears which contains a large proportion of the second, third and fourth harmonics and a small proportion of the root tone. These overtones are in the speaker's transmission range when the root tone is in the range of 3-800 Hz.

Ved hjælp af den anviste udformning af alarmsignalgeneratoren kan de strømme, som løber i forstærkerens 5 udgangstransistorer og transformeren 7 holdes små.By means of the design of the alarm signal generator, the currents running in the output transistors of the amplifier 5 and the transformer 7 can be kept small.

I blokdiagrammet er udgangstransistorerne ikke vist detaljeret, men de indgår i to forstærkere 8 og 9 som i forbindelse med udgangstransformeren 7 danner et modtaktsudgangs trin .In the block diagram, the output transistors are not shown in detail, but they are included in two amplifiers 8 and 9 which, in connection with the output transformer 7, form a reception output stage.

Som antydet i fig. 1 kan firkantgeneratoren være udformet således, at den kan frembringe to forskellige frekvenser 4f^ og 4f2 skiftevis styret af et periodisk styrekredsløb 10.As indicated in FIG. 1, the square generator can be designed to produce two different frequencies 4f ^ and 4f2 alternately controlled by a periodic control circuit 10.

Claims

149671

An alarm signal generator supplying a pressure chamber loudspeaker (6) whose transmission range is above a predetermined fundamental tone frequency of the alarm signal to be emitted by the speaker, which alarm signal (Fig. 2d) contains a large proportion of overtones located in the transmission range of the loudspeaker (6), characterized in that the alarm signal is an alternation of two signal forms composed of a square signal consisting of a first square signal (4f) with the frequency of the fourth overtone and a second square signal (2f) with the frequency of the second overtone, alternating with the frequency of the fundamental tone (f) between the two square signals (4f, 2f) such that alternating at the output (A) of the alarm signal generator during one half period of the root tone (f) occurs two periods of the first and during the second half period of the root tone a period of the second square signal as an alarm signal ( Fig. 2d).

An alarm signal generator according to claim 1, characterized by comprising a square generator (1) generating the first square signal (4f), a first frequency divider (2) dividing the first square signal (4f) in the ratio of 2: 1 to produce it. a second square signal (2f), a second frequency divider (3) dividing the second square signal (2f) in a ratio of 2: 1 to produce a control signal (f), and a switch (4) having a first contact (u) connected to the output of the square generator (1), and a second switch (v) connected to the output of the first frequency divider (2) and a contact arm which, as the control signal (f) swings between the two contacts (u) , v) and alternates with the root tone frequency (f) first