JPS59175221A - Decoder circuit for traffic information district tone signal - 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 The present invention relates to a decoder circuit for decoding regional tone signals of traffic information.

This local tone signal is included in the received broadcast signal in the form of an amplitude modulated (AM modulated) carrier. This broadcast signal is transmitted within a conventional radio receiver.
It has already been demodulated.

According to the publication ``Funkchau'' (1974, pp. 535-538), a recent system for broadcasting traffic information to radio receivers in West Germany and other European countries is disclosed. . According to this system, a territory is divided into several traffic information areas and regional tone signals are added to the traffic information signals. These regional tone signals are low frequency signals, and their frequency, ie, the regional tone frequency, is information about the region. In known systems, this tone signal is
57 kHz (AM modulated on carrier IJ 7 with zero frequency.

Such a traffic information broadcasting system is published in the publication “Run
dfunktechnlsche Mitteilun
gen” (1974, pp. 193-2o2) K. According to this publication, the decoder for automatic traffic information reception (9 decoding circuits are compatible with ordinary analog signal processing receiving circuits). The system node has been selected to be g-compatible and therefore not to interfere with this receiving circuit.
The decoder circuit used here is also an analog circuit.

According to the present invention, an integrated circuit is provided as a circuit for decoding (decoding) such a traffic information area tone signal, and this circuit is operated based on the principle of digital technology, so that most of this circuit is It consists of digital subcircuits. Such a digital circuit has a fast response speed of less than 1 second, for example 300 mS, and is protected from noise when recognizing each region.

The invention is characterized in that the broadcast signal demodulated in the usual way is first converted to a very low intermediate frequency and then changed from analog to digital form.

Additionally, four quality conditions are monitored in order to reliably recognize this regional tone signal.

Only when these four conditions exist simultaneously will the decoded signal be used. These four conditions are channel spacing composite channel spacing, modulation depth and presettable time threshold.

The response performance of the circuit of the present invention can be improved (fastened) without deteriorating the decoding performance. Furthermore, this circuit is practically noise and interference resistant. The configuration for monitoring these four conditions includes a controller and an AND dart.

The present invention will be described in detail below with reference to the drawings.

FIG. 1 shows an embodiment of a decoding integrated circuit according to the present invention, by means of which a local tone signal for traffic information can be decoded.

In the figure, a demodulated broadcast signal (da) obtained by an ordinary radio receiver is supplied to a mixer (m8). The local oscillation frequency (oscillation frequency of a local oscillator) fm of this mixer ma is higher than the highest local tone signal frequency fb. In the systems described in the two aforementioned publications, the local frequency fmld-1 region "F"
The regional tone frequency assigned to the network is 53.98 Hz. In an actual circuit, the local oscillation frequency fm becomes 223.5 Hz. The frequency of the local tone signal modulated onto the carrier by the mixer ms is converted into the local frequency fm.

The output signal of the mixer ma is supplied to the input of the converter &W via an analog loaf filter aff. The upper cutoff frequency of this loaf 4-filter af is half the sampling frequency of the maximum converter mW.

The output terminal of this A/i) converter jLW is connected to the input terminal of a digital band/4' filter bp.

The intermediate frequency f0 of this filter bp is the difference between the carrier frequency ft and the local frequency fm, that is, fa − ft” f
Corresponds to m.

The output terminal of this A/b converter aw is also connected to the first input terminal of a multiplier m. This multiplier m
The second input terminal of the digital pantonose filter b
Connected to the output terminal of the digital clamp circuit Kt at the subsequent stage of p. This digital clamp circuit KL clamps the positive and negative input signals to the positive and negative maximum values, respectively. These maximum values are determined by the number of digits of the input signal.

Here, the φ converter aw and can also be made to directly follow the mixer ma as in the modified input circuit shown in FIG. In this case, along with the converter ay delta/sigma converter, the digital pantone? It is necessary to insert a one-digital φ low-pass filter AF between the input terminal of the filter bp and the output terminal of the φ converter/S-controller aW.

By providing a digital band filter, the local oscillator signal can be recovered, and the digital clamp circuit KL
Standardize the amplitude of this signal by .

On the other hand, a large number of signal paths are connected to the output terminal of the multiplier m, and one of these signal paths corresponds to the tone frequency of each region.

In FIG. 1, the passage a + b a / is illustrated.
Each signal path consists of a digital resonant filter rm h rb m r/ for a respective regional tone frequency /b, these resonant filters r & mrb * r
There is a digital absolute value type layer after each /? % ha
* bb + bf and digital low-pass filters pa, pbr pf are connected, the upper cut-off frequency of this filter being set to a value twice as low as the lowest regional tone frequency. In the conventional system described above, this lowest local tone frequency assigned to the local AK has a value of 23.75 Hz.

The function of the three subcircuits in each of these three signal paths a+b+f is selective level measurement.

The output terminals of each of the loaf four filters plL h pb #pf are connected to one of the input terminals of a multidel comparator vK. The first maximum output terminal mX1 of this comparator VK supplies a signal indicating the signal path. This signal path is the largest signal,
That is, because of the number of signal paths +7)7' digital words are transmitted, the maximum signal value appears at the first maximum output terminal mX1. Similarly, the second maximum output terminal mX2
Alternatively, a signal is provided specifying the number of signal paths carrying the second maximum signal.

The first and second maximum output terminals mX1 and mX2,
It is connected to the control input terminals of the first and second electronic multidel switches Sl and S2, respectively. The input terminals of these switches s1 and s2 are connected to the output terminals of the aforementioned loaf four filters pa, pb and pf. Therefore, these two multiple switches sl.

The input terminals of S2 are as many as the number of signal paths, and depending on the signals at the first and second maximum output terminals mx1 and mx2, these switches St, Sz'
are connected to signal paths that transmit a maximum signal value and a second maximum signal value, respectively.

The output terminal of the first multiple switch S1 is connected to the minuend input terminal of the first converter KL via the first constant multiplier m1, and the subtrahend input terminal of this is connected to the output terminal of the multiple adder (addition!) ad. do. The input terminal of this adder ad is connected to the aforementioned low-pass filter pa'.
+ Connect to each of pb and pf. The output terminal of the first multisol switch S1 is also connected to the minuend input terminal of 2 to the second comparator via a second constant multiplier m2. The subtractive input terminal of 2 is connected to this comparator to the output terminal of the second multiple switch S2.

2 to the second comparator and a second constant multiplier m
2 determines whether the amplitude of the first maximum signal multiplied by a constant factor is greater than the second maximum signal. This constant, used as a multiplication factor in this second constant multiplier m2, allows the channel spacing to be fixed.

Similarly, the level of the first maximum signal is compared with the sum of the signal values of the other signal paths by means of the first constant multilayer m and the first controller KIK. This comparison operation is a measurement of the sA value.

The first maximum output terminal mX of the multidel comparator vK
l is connected to the delay element Vg, and the output terminal of this element is connected to the third
Connect the minuend input terminal of 3 to the comparator of . The subtractive input terminal of 3 is connected to the first maximum output terminal mX1 of this converter. This third comparator has 3 “i”
The output terminal ``subtraction equals subtraction'' is connected via an input terminal It to the reset input terminal er of a counter Z, at whose counting input terminal the clock signal t appears. is connected to the minuend input terminal of 4 to the fourth converter.

A constant K used as a threshold value is applied to the subtractive input terminal of 4 to the fourth configurator. The sub-circuit described above, namely the delay element Vg, 3 in the third comparator, 4 in the inverter tt, counter 2 and 4 in the fourth comparator, under the following conditions, the minuend of 4 is in the fourth comparator. A signal is generated at the large ``'' output terminal. That is, the above-mentioned signal is generated only when the first maximum signal is constant for a period determined by the clock signal t and the constant frequency. In this way, time thresholds are realized by these subcircuits.

The output terminal of the digital bandpass filter bp is connected to an additional digital absolute value former bw, to which an additional digital low pass filter pw is connected. The upper cutoff frequency of this filter pw is the aforementioned low-pass filter pa.

It is set equal to the cutoff frequency of pb and pf. The output terminals of this filter pw are connected to the third and fourth output terminals.
the fifth through constant multipliers m3pm4, respectively.
and the sixth controller are connected to the subtraction input terminals 5 and 6, respectively.

5 to these comparators. The minuend input terminal of 6 is connected to the first
Connect to the output terminal of the multiple switch S1. Fifth
The first AND gate U outputs the output terminals of the comparator of 5 and 6 whose minuend is larger than the subtrahend, and the output terminal of the 6th comparator that shows that the minuend of 6 is smaller than the subtrahend.
Connect to the two input terminals of 1. Still, these sub-circuits, i.e. an additional magnitude former, an additional digital
Low-pass filter pw, constant multiplier m 3 *
m 4, 5 to the comparator. 6 and ANT) r-
) IJl allows the depth of modulation of the regional tone signal to be monitored. This is because noise appears as the depth of modulation increases. On the other hand, this is because the unmodulated carrier frequency generates noise.

To monitor the depth of this modulation, the first maximum signal is
The amplitude of the local signal is compared with respect to the upper and lower thresholds.

These thresholds are determined by the respective constants of third and fourth constant multipliers m3 and m4.

(2nd AND) Connect the four input terminals of U2 to the first and second
and 1 to the fourth comparator. is connected to the output terminal of 2°K4 whose minuend is larger than the subtrahend and to the output terminal of the first AND gate U1, respectively.
The output terminal of this AND gate VU is the regional tone signal output terminal Sa of the integrated circuit, and the output terminal of the second AND gate U2 is connected to the parallel input terminal of the multidel AND f-) VU. Second
Connect to all terminals of the Norarel input terminal. this! In the ICL, it is possible to check whether the four conditions to be monitored exist simultaneously by means of a second AND gate U2. Only when this requirement is met, the number of regions combined with this will be transmitted to the above-mentioned regional tone signal output terminal SaK.

Therefore, according to the present invention, by using four quality conditions, regional tone signals can be verified with high reliability. Only when these four conditions exist simultaneously,
Multiple radical signals are output from the integrated circuit.

These four conditions are channel spacing, total channel spacing, modulation depth, and a presettable time threshold value. Although a circuit network with a certain capacity is required to monitor these four conditions, the response time of the entire circuit can be shortened without impairing decoding performance. This is one of the features of the present invention. Furthermore,
The circuit of the invention has practical advantages against noise and interference.

FIG. 3 shows an embodiment of the mixer ma. This mixer m
a is a dyne "1" amplifier ■1 and an electronic switch S
It is made up of many things. The control signal for this electronic switch S is the local oscillation signal fm. The amplifier v1, which has a gain of "1" compared to a conventional analog amplifier, generates a signal whose phase is shifted by 180 degrees with respect to its input signal. Furthermore, when this electronic switch S is switched to one position, the broadcast signal da, which is also supplied to the input terminal of this amplifier v1, is output directly to the output side of this switch S,
When switched to the other position - this signal d8 becomes 18
The 0° phase is shifted and output. In this example, the aforementioned local oscillation signal fm is a rectangular wave signal.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an embodiment of the circuit of the present invention, FIG. 2 is a block diagram of a modification of the input section of FIG. 1, and FIG. 3 is a specific circuit diagram of the mixer of FIG. 1. It is. m8...mixer, af...analog low back filter, aW...L converter 1 palpbIp
fIpw...Digital Rohno flat filter, ad
...Ata-1Vx...Multi-Delconts Crater,
Kl. K2, ni 3, ni 4 #, ni 5, ni 6... Connogrator, m r m 1 z m 2 * m 3 *
m 4... Multiplier, S1#S2... Electronic switch, 2... Counter.

Claims (1)

[Claims] 1. In order to decode a regional tone signal for traffic information that is amplitude-modulated with a demodulated broadcast signal carrier, while receiving this demodulated broadcast signal, the most of the regional tone signals are a mixer coupled to a local oscillator having a higher frequency; a double converter coupled to the output terminal of the mixer; a dopass filter coupled to the output terminal of the double converter; iJ? an input terminal coupled to an output terminal of the filter, and a digital clamp circuit operative to clamp positive and negative valued signals to maximum positive and negative values respectively determined by the number of digits of said input signal. , a multiplier having a first input terminal coupled to an output terminal of the third converter and a second input terminal coupled to an output terminal of the digital clamp circuit; Maximum value of 2 is 7
one of the plurality of input terminals having an output terminal of the plurality of digital low-pass filters is coupled to an output terminal of the electronic multiple switch in response to the second maximum value; a multiple adder having a plurality of input terminals and an output terminal respectively coupled to each other; a first input terminal coupled to the output terminal of the multiple adder; a second input terminal having a second input terminal and an output terminal; a first constant multiplier coupling all output terminals of the first electronic multiple switch to a second input terminal of the multidel adder; and a first input coupled to an output terminal of the second electronic multiple switch. a second comparator having a terminal, a second input terminal, and an output terminal; a second constant multiplier coupling the output terminal of the first electronic multiple switch to the second input terminal of the second comparator; a first input terminal coupled to the first maximum output terminal;
a third comparator having an input terminal and an output terminal; a delay element coupling the first maximum output terminal to a second input terminal of the third comparator; a counting input terminal for receiving a clock signal; a first input terminal coupled to the output terminal of the counter; and circuit means for coupling the output terminal of the third comparator to the reset input terminal; - a fourth comparator having a second input terminal receiving a constant serving as a hold value and an output terminal; a digital magnitude former coupled to the output terminal of the digital bandpass filter; a second digital loaf filter coupled to the output terminal of the absolute value former and having a predetermined upper cutoff frequency; a second digital loaf nine filter coupled to the digital loaf nine filter, each having an output terminal; 3 and a fourth constant multiplier; a first input terminal coupled to the output terminal of the third constant multiplier; and a second input terminal coupled to the output terminal of the first multiple electronic switch. and an output terminal; a first input terminal coupled to the output terminal of the fourth constant multiplier; and a first input terminal coupled to the output terminal of the first multidel electronic switch. a sixth comparator having two input terminals and an output terminal; tenth chic means coupled to the first, second, fourth, fifth and sixth comparators for generating a dart signal; an input terminal coupled to a maximum output terminal of the first maximum output terminal, a dart input terminal for receiving the date signal, and an output terminal, the first maximum output terminal being responsive to the dart signal. a plurality of signal paths each having an input terminal coupled to an output terminal of the multiplier; A digital absolute value former and a digital absolute value generator are combined in this signal path.
A digital resonant filter is provided which is followed by a low-pass filter, and the upper cutoff frequency of the low-pass filter is set lower than twice the lowest frequency of the previous regional tone signal. a multiple converter generator having a first and a second maximum output terminal, each of the low bus filters having a first output terminal coupled to one of the input terminals of the multidel converter generator; the first and second electronic multiple switches are provided with control input terminals respectively connected to the first and second maximum value output terminals of the multiple converter/4'converter; further comprising a plurality of input terminals; Establishment of the digital law/I
an output terminal coupled to one of the plurality of input terminals of the first multisol switch and one of the plurality of input terminals of the second multisol switch; a plurality of input terminals having a first maximum value;
A decoder circuit for a local tone signal for traffic information combined with a radio receiver, characterized in that a decoder circuit for a local tone signal for traffic information is coupled to an output terminal of the first multidel switch. 2. The circuit according to claim 1, wherein the circuit for decoding the local tone signal of the traffic information is formed of an integrated circuit. 3. The circuit of claim 1 further comprising an analog low-pass filter coupled between the mixer and the third converter and having the predetermined cutoff frequency. 4. The circuit according to claim 3, wherein the predetermined cutoff frequency is set to be no higher than 1/2 of the sampling frequency of the converter. 5. The circuit according to claim 1, wherein the triple converter is a sigma/delta converter. 6. The circuit according to claim 5, characterized in that a digital low/yas filter is coupled between the converter and the digital band Nori filter. 7. The mixer is provided with an electronic switch having two input terminals, a control input terminal and an output terminal, and an inverting dyne 1" amplifier, and the output terminal of this amplifier is connected to the two input terminals of the electronic switch. the demodulated broadcast signal is received by the other of these two input terminals and the input terminal of this amplifier, and the control input terminal of the electronic switch is coupled to the local oscillator and from there. 8. The circuit according to claim 1, wherein the circuit receives a rectangular wave signal. 8. The mixer includes: an electronic switch having two input terminals, a control input terminal and an output terminal; an amplifier of 61'' for use, the output terminal of this amplifier is connected to one of the two input terminals, and the demodulated broadcast signal is received by the other of the two input terminals and the input terminal of this amplifier. 3. The circuit of claim 2, wherein the electronic switch control input terminal is coupled to and receives a square wave signal from the local oscillator. 9. The mixer is provided with an electronic switch having two input terminals, a control input terminal and an output terminal, and an amplifier with an inverting die of "1", and the output terminal of this amplifier is connected to the two input terminals of the electronic switch. the demodulated broadcast signal is received by the other of these two input terminals and the input terminal of this amplifier, and the control input terminal of the electronic switch is coupled to the local oscillator and from there a rectangular 10. The mixer includes: an electronic switch having two input terminals, a control input terminal and an output terminal; and an inverting dyne. an amplifier of "1", the output terminal of this amplifier is connected to one of the two input terminals of the electronic switch, and the demodulated broadcast signal is transmitted by the other of these two input terminals and the input terminal of this amplifier. 5. The circuit according to claim 4, wherein a control input terminal of said electronic switch is coupled to said local oscillator and receives a square wave signal from said local oscillator. 11. The mixer is provided with an electronic switch having two input terminals, a control input terminal and an output terminal, and an amplifier with an inverting gain of ``1'', and the output terminal of this amplifier is connected to the two input terminals of the electronic switch. one of the terminals so that the demodulated broadcast signal is received by the other of these two input terminals and the input terminal of this amplifier, and the control input terminal of the electronic switch is coupled to the local oscillator. 6. The circuit according to claim 5, wherein a rectangular wave signal is also received from the circuit. 12. The mixer is provided with an electronic switch having two input terminals, a control input terminal and an output terminal, and an amplifier of inverting dyne "'l", the output terminal of this amplifier being connected to the two input terminals of the electronic switch. the demodulated broadcast signal is received by the other of the two input terminals and the input terminal of this amplifier, and the control input terminal of the electronic switch is coupled to the local oscillator; Claim 6, characterized in that a rectangular wave signal is received.
The circuit described in section.