JPS63133199A - Electronic siren - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION A. Field of Industrial Application The present invention relates to an electronic siren that generates a siren-like sound by electronic means.

B0 Summary of the Invention In a signal generator using a microcomputer,
The frequency change is created by a set of step-like straight lines obtained by calculation using table data (starting frequency, frequency increase rate, etc.).

In an advantageous embodiment of the invention, the calculation result is output by calculation using the integer part of the output frequency.

In another embodiment, the sum of the durations of the signals of frequencies corresponding to the straight line is calculated by the system clock.

C0 Prior Art Most conventional electronic sirens use a multivibrator or voltage controlled oscillator (VCO). FIG. 6 is a block diagram showing the configuration of an example of this type of electronic siren, in which 1 is a control voltage generation circuit, 2 is a voltage controlled oscillator (CO), 3 is an amplitude modulation circuit, and 4 is an amplifier. ,5
represents a speaker, and S represents a siren switch. This method had the following drawbacks.

(i) The siren frequency, rise characteristics, and damping characteristics vary due to variations in parts, and many adjustments are required.

(n) Characteristics change significantly due to temperature changes, and temperature correction is required.

(fit) Many parts are required and the number of man-hours is large.

(iv) With analog systems, the siren sound is fixed and multiple sounds cannot be emitted.

Another method is the PCM method, but this method is only possible when the siren sound is short and repetitive, such as a beeping sound. In addition, siren sounds are mostly rectangular waves, so they contain very high frequency components.
To reproduce this waveform, the sampling frequency must be increased, and this method has the disadvantage of requiring a large amount of memory.

Problems to be Solved by the D0 Invention Taking as an example the woo-woo sound, which is the standard sound of pyroelectronic sirens, this sound has large frequency changes and is long in time, so it is difficult to convert it to PCM due to memory capacity. It was possible.

An object of the present invention is to provide an electronic siren that does not rely on PCM.

Means for Solving the E0 Problem In order to achieve the above object, the electronic siren according to the present invention is obtained by calculation using table data including the starting frequency, frequency change per unit time, and other necessary data. , a microcomputer that calculates frequency changes from a set of step-like straight lines in a frequency-time graph; an electronic circuit that generates and amplifies electrical oscillations at a frequency determined by instructions from the microcomputer; =3- A speaker that converts the generated electrical signal into sound.

In one embodiment of the present invention, only the integer part of the frequency determined by the command from the microcomputer is output as an electrical signal.

In another embodiment of the invention, the sum of the durations of the signals of frequencies corresponding to the straight line is calculated by the system clock.

Based on the frequency of the F8 working quartz oscillator, the frequency is changed according to instructions from a microcomputer, and the frequency distribution of the siren sound is approximated by a number of straight lines that change stepwise.

G. EXAMPLES The present invention will be explained in more detail below using examples with reference to the drawings, but these are merely illustrative and various modifications and improvements can be made without going beyond the scope of the present invention. Of course it is possible.

FIG. 1 is a block diagram showing the configuration of an electronic siren according to the present invention. In the figure, reference numbers common to FIG. 6 represent parts that are the same as or correspond to those in FIG. 6, and S2 is a manual siren. Switch, S3 is automatic siren switch, S4 is siren tone changeover switch, 6 is 4
A bit or 8-bit microcomputer, 7 is a 12-bit D/A converter.

FIG. 2 represents the frequency distribution curve of a manual siren. This N
So, the starting frequency is 50 H and the highest frequency is 800 H.
7, where T1 is the rise time, T2 is the saturation time, and T3 is the decay time.

That is, driving of the siren is stopped at the end of T2.

The actual frequency distribution curve is a smooth curve, but here it is approximated by a set of straight lines (eight straight lines from ■ to ■ in the figure) as shown.

FIG. 3 represents only the first part of the curve of FIG. 0.
Assuming that the starting frequency increases from 507 to 460■ in 5 seconds, the frequency increase rate per unit time is Δt = 500ms Δf = 460 - 50 = 410
7, so D = Δf/Δt = 41010.5 = 8207/S.

This straight line is further approximated by a group of stepped straight lines, as shown in FIG.

F: Starting frequency ΔF, 2 Frequency change amount ΣT, 1: Total time from starting frequency D =
Frequency increase rate Fl: If it is the output frequency, the following equation holds true.

F, = F + ΔF1 ΔF, = (ΣT, 1) X D T5-1 = 1 / Fy-1 If the starting frequency is 50 balls and T is 20 m5,
F becomes as follows.

ΔF1 = (20x 1O-3) x 820 = 1
6.41kF,=F+ΔFt=50Hz+16
．． 4 Hz = 66.4 Hz Next, F2 is obtained as follows.

T, -t = 1/F, -t = 1/66.4 I(z
=15.060241 msΔF2 = (20x
], 0-3+ 15.060241 x 1O-3)=
28.7497F2 ” F + AF2 = 50 T(z + 2
8.749 Hz, 78.7497 and below In the same way, H3, H4, etc. are calculated sequentially, but there is an error between the actual output frequency and the calculation result. This is because the minimum instruction execution time of a microcomputer is determined based on the system clock, which naturally determines the frequency resolution. Calculating the deviation from the actual result, in the case of ■, the calculation result is F1 = 66.4 I(z, period is 1
/F, = 15.060241 ms. If the microcomputer's instructions are 1 μs, the periodic resolution that can be output is 1 μs or more.

Therefore, 15.060241 m5 becomes an output of 15060.0 μs. Therefore, the error is 15060.241
tts −15060, Otts=Q, 24.1 μ
It is s.

From the above, in order to reduce this error, in the internal calculation of the microcomputer, a calculated cycle is used for 21M-1 rather than the system clock or the actual output cycle.

If the periodic change is less than 1 μs, the same frequency will naturally be repeated. Whether or not the table data has been completed is determined by whether F, = 4.60Hz has been reached.

When the range from 50Hz to 460Hz is completed in this way, the process moves to data (2). At this time, the starting frequency F becomes 4.60 Hz. Use the new data for the frequency increase rate and perform the same calculation as last time.

Next, during the saturation time T2, the frequency increase rate D 2 is calculated as O, and the same frequency is continuously output.

When the siren switch is turned off, the decay time T3 begins, and calculations are performed in the opposite direction to those for the rise.

The automatic siren is similar, and at T2, it is checked whether a certain period of time has elapsed, and the process moves to the attenuation characteristic.

In the above calculations, unless the calculation speed is increased, the frequency resolution will be greatly affected, so complex calculations should not be performed. Therefore, since calculating the output frequency of the calculation result using real numbers requires a long calculation time, integer division is used to achieve high resolution. That is, 835.253Hz is 835
1 (calculated as z.

FIG. 5 is a flowchart showing the above operation.

H6 Effects of the invention As explained above, according to the invention, the following advantages can be obtained.

(1) Since the siren frequency is based on quartz oscillation, the frequency change due to temperature changes is very small.

It is stable.

(2) Compared to analog systems, there is no need for adjustment.

(3) Multiple siren sounds can be easily output by switching.

(4) Compared to PCM, memory capacity is extremely small.

In addition, the electronic siren according to the present invention can produce various siren sounds at a very low cost, and can be applied to toy police cars and emergency sounds.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing the configuration of an electronic siren according to the present invention, FIG. 2 is a diagram showing a frequency distribution curve of a manual siren, and FIG. 3 is a diagram showing only the first part of the frequency distribution curve of FIG. FIG. 4 is an explanatory diagram of the approximation method of the present invention, FIG. 5 is a flow chart showing the approximation method of the present invention, and FIG. 6 is a block diagram showing the configuration of an example of a conventional electronic siren. 4......Amplifier, 5......Speaker, 6......Microcomputer,
7...D/A converter, F...
...Start frequency, AF, ...Frequency change amount, ΣT, ......Total time from start frequency, D...Frequency Rate of increase, Fw...
・・・・・・Frequency to be output. Patent applicant: Clarion Co., Ltd.

Claims (3)

[Claims] (1) (a) Calculate the frequency change from a set of stepped straight lines on a frequency-time graph obtained by calculation using table data including the starting frequency, frequency change per unit time, and other necessary data. a microcomputer; (b) an electronic circuit that generates and amplifies electrical vibrations at a frequency determined by instructions from the microcomputer;
and (c) an electronic siren characterized by including a speaker that converts an electric signal generated by the electric circuit into sound. (2) Claim 1, characterized in that the electrical signal is output as an electrical signal by calculation using an integer part of a frequency determined by a command from the microcomputer.
Electronic siren as described in section. (3) The electronic siren according to claim 1, characterized in that the sum of durations of signals of frequencies corresponding to the straight line is calculated by a system clock.