WO2008000336A1

WO2008000336A1 - Car radio comprising at least one first reception channel and a second reception channel and corresponding car radio

Info

Publication number: WO2008000336A1
Application number: PCT/EP2007/004934
Authority: WO
Inventors: Hervé Ducoffe
Original assignee: Continental Automotive France
Priority date: 2006-06-29
Filing date: 2007-06-04
Publication date: 2008-01-03
Also published as: FR2903251A1; FR2903251B1

Abstract

The invention relates to a car radio comprising at least one first reception channel and a second reception channel, each compatible with at least one type of radio modulation, wherein the first reception channel comprises a first receiving antenna (211) compatible with said type of radio modulation. According to the invention, in such a car radio (200), one part of the first reception channel dedicated to processing at least said type of radio modulation is common to the second reception channel.

Description

AUTORADIO COMPRISING AT LEAST ONE FIRST RECEIVING CHAIN AND A SECOND RECEIVING CHAIN AND AUTORADIO CORRESPONDING

The field of the invention is that of electronic devices for receiving radio signals.

More specifically, the invention particularly relates to car radios with multiple reception channels, a reception channel mainly comprising a reception antenna 5 connected to at least one tuner.

Multi-channel car receivers with two AM tuners ("Amplitude Modulation", hereinafter "AM modulation") / FM (for "Frequency Modulation", hereinafter referred to as "FM modulation") and two antennas AM / FM have already been developed (for example, as illustrated in US patent document US 6141536) to realize, for example, the "FM living band" which consists of a permanent search by the second tuner FM stations available in the background of the listening station of the first tuner.

With reference to FIG. 1, this type of car radio is presented, based on a first AM / FM antenna 111 and a second AM / FM antenna 121, respectively connected to first and second separate AM / FM tuners 13 and 14. These tuners are connected to a signal processor of DSP type 15 (for "Digital Signal Processor" or "digital signal processor" in French) itself connected to loudspeakers 16 and 17.

A disadvantage of this first solution (two antennas and two tuners) lies in the need to have two AM channels and two complete FM channels (antenna and tuner) to receive the AM and FM stations. This solution is therefore cumbersome and expensive because of the presence on the same printed circuit of two separate tuners and two receiving antennas.

Car radios with multiple reception channels have also been developed in order to be able to listen to different AM or FM reception programs as described in US20050191979. This document describes a radio receiver comprising two AM / FM tuners and a single AM / FM compatible receiving antenna shared between the two tuners using an antenna splitter. This splitter is placed just before the AM filter of the first tuner of the HF stage (high frequency) of the first tuner and the beginning (just before the AM filter of the second tuner) of the HF stage of the second tuner. This solution implemented in the automotive world is better known as "front seat rear seat" and offers the possibility of listening to two different audio streams in different spaces. (for front passengers and rear passengers, for example).

Despite the economy of a second antenna compared to the first solution, this second technical solution (an antenna, a splitter and two tuners) requires the implementation of an AM and FM compatible antenna splitter upstream of the car radio which leads to a certain size and an additional cost.

Thus, these first and second solutions lead to bulky and expensive car radios due in particular to the presence of either two antennas or an antenna splitter upstream of the car radio.

Moreover, the presence of two separate tuners on the same printed circuit also leads to significant congestion and cost and increases the risk of occurrence of quality problem related to the production of these two tuners because of the large number of components used. artwork. The invention particularly aims to overcome these disadvantages of the prior art.

More specifically, an object of the invention, in at least one of its embodiments, is to provide a technique for obtaining a car radio with several reception channels compatible with at least one type of modulation, the receiver requiring that a single receiving antenna compatible with the type of modulation without requiring an antenna splitter.

Another objective of the invention, in at least one of its embodiments, is to provide such a technique which makes it possible to reduce the costs, the size and the quality constraints of the receiver. These objectives, as well as others that will appear later, are achieved by means of a car radio comprising at least a first reception channel and a second reception channel, each compatible with at least one type of radio modulation, the first reception channel comprising a first reception antenna compatible with said type of radio modulation. According to the invention, in such a car radio, a part of the first reception channel dedicated to processing at least said type of radio modulation is common with the second reception channel.

The general principle of the invention is based on a pool of means through appropriate connections when producing reception channels compatible with at least one type of modulation of a car radio.

Thus, it is possible, for example, to use the same reception antenna compatible with at least one type of modulation for several reception channels without resorting to the use of antenna splitters.

This pooling also makes it possible to overcome the multiplication of the means pooled during the production of reception channels and thus to make a car radio less cumbersome and less expensive than conventional car radios. We can distinguish a first case where the part of the first reception channel is only dedicated to a first type of modulation (for example AM or FM) of a second case where this part is dedicated to both types of modulation ( for example both FM and AM). Advantageously, said part of the first reception channel comprises the first antenna and first filtering means dedicated to the first type of modulation and connected to the first antenna.

Thus, at least one use of the first antenna is common to both reception channels. Preferably, the car radio further comprises means for connecting an output of the first filtering means, dedicated to said type of modulation, to an input of a mixer, dedicated to said type of modulation and belonging to the second reception channel.

According to a first advantageous implementation of the invention, the connection means comprise means for direct connection between: a mixer dedicated to said type of modulation and belonging to the first reception channel; and a mixer dedicated to said type of modulation and belonging to the second reception channel - According to a second advantageous implementation of the invention, the connection means comprise capacitive connection means making it possible to establish an alternative connection between: a mixer dedicated to said type of modulation and belonging to the first reception channel; and a mixer dedicated to said type of modulation and belonging to the second reception channel.

Advantageously, an intermediate frequency path dedicated to the type of modulation of the first reception channel is merged with an intermediate frequency path dedicated to the type of modulation of the second reception channel. According to an advantageous characteristic of the invention, the type of radio modulation belongs to the group comprising: amplitude modulations; frequency modulation.

It should be noted that it is easier to achieve the pooling of at least two reception channels according to the invention for the amplitude modulation (AM) than for the frequency modulation (FM) because the filters used for AM modulation are wider than the filters used for FM modulation. However, it is conceivable to implement a larger FM filter at the first reception channel and a more tolerant FM mixer when processing the frequencies received at the second reception channel.

Other characteristics and advantages of the invention will appear more clearly on reading the following description of several embodiments of the invention, given by way of simple illustrative and non-limiting examples, and the appended drawings, among which: Figure 1 shows the diagram of a conventional car radio with dual reception chain; Figure 2 shows a diagram of a car radio comprising two reception channels both compatible with the AM and FM modulations according to a first embodiment of the invention; FIGS. 3A and 3B illustrate two modes of implementation according to the invention of connection means. FIG. 2 shows the diagram of a car radio 200 comprising first 21 and second 22 reception channels that are both compatible with the AM and FM modulations according to a first embodiment of the invention.

The first reception channel 21 comprises a first antenna 211, a first FM filter 212, an AM 213 filter, a first FM mixer 214, a first AM 215 mixer, a first AM / FM filter 216 and a first amplifier 217 (forming a first antenna 211 and a first tuner).

The second reception channel 22 comprises a second antenna 221, a second FM filter 222, a second FM mixer 224, a second AM 225 mixer, a second AM / FM filter 226 and a second amplifier 227 (forming a second antenna and a second tuner).

The car radio 200 also includes a signal processor 25 and two speakers 26 and 27.

The car radio 200 also comprises connection means 28 for the output 2131 of the AM 213 filter of the first reception channel 21 to the input 2251 of the second AM 225 mixer of the second reception channel 22.

Thus, in this car radio 200, part of the first reception channel 21 is common with the second reception channel 22.

This common part includes the first antenna 21 as AM antenna and the AM filter 213. Thus, this common part is dedicated to AM modulation. Of course, in addition to the AM and FM modulations, the invention also applies to any other type of modulation, for example phase modulation. Moreover according to a variant (not illustrated) of this first embodiment, the common part is dedicated to FM modulation. For example, this common part could consist of the first antenna 21 as an FM antenna and the FM filter 212, in which case the second modulation system would not include an FM filter but only an AM filter and the connection means would connect the FM output of the FM filter 212 to the input of the FM 224 mixer. On the other hand, according to a second embodiment (not shown), the common part is dedicated not only to the AM modulation but also to the FM modulation.

Three modes of implementation of the connection means 28 according to the invention are presented in relation to FIGS. 3A and 3B.

In these FIGS. 3A and 3B, the two capacitors C21 (for example 10OnF) and C11 (for example 1nF) and the coil S11 (for example 1mH) are part of the filter AM 213 of FIG.

It will be noted that in the context of the implementations of FIGS. 3A and 3B, the output 2131 of the AM 213 filter consists of two outputs 21311 and 21312, the input 2251 of the second mixer AM 225 consists of two inputs 22511 and 22512. Similarly, the inlet of the first mixer AM 215 consists of two inputs 2151 and 2152.

The coil S11 connects the two inputs 2151 and 2152 of the first mixer 215 and allow to place these two inputs at the same potential continuously.

According to the first embodiment of the invention (FIG. 3A), the connection means 28 comprise two conductive strips (for example metal strips or electrical wires) connecting the inputs 2151 and 2152 of the first mixer AM 215 respectively to the 22511 and 22512 entries of the second AM 225 mixer. Thus, these connection means form direct link means for establishing a direct connection between the first mixer AM 215 and the second mixer AM 225.

The coil S11 also connects the two inputs 22511 and 22512 of the second mixer 225 and allow to place these two inputs at the same potential continuously.

Thus, a continuous and AC connection is made between the output of the filter AM 213 and the input of the second mixer AM 225.

According to the second mode of implementation of the invention (FIG. 3B), the connection means 28 comprise two capacitors C42 of 1nF and C32 of 1 nF respectively connecting the two inputs 2151 and 2152 of the first mixer AM 215 to the inputs

22511 and 22512 of the second mixer AM 225. The connection means 28 also comprise a coil S22 of 1 mH connecting the two inputs 22511 and

22512 of the second mixer 225 and to place these two inputs at the same potential continuously. The connection means 28 also comprise a capacitance C52 of 10OnF connecting the input 22512 of the second mixer AM 225 to ground.

The decoupling capacitors C32, C42, C52 make it possible to block the continuous components of the signals flowing in the connection means and thus make an AC connection only between the output of the AM 213 filter and the input of the second AM 225 mixer.

Thus, these connection means form capacitive connecting means for establishing an AC connection between the first mixer AM 215 and the second mixer AM 225.

In the context of the aforementioned first and second embodiments, the inputs of the AM mixers are placed at the same potential continuously. For example, AM mixers are AM mixers integrated in the integrated circuit marketed under the reference Dice2 TEF6730HW by PHILIPS. Thus, the first 215 and second 225 AM mixers are connected in parallel thanks to the connection means 28.

It is also possible to share the paths Fl (for "Intermediate Frequency") dedicated to AM and FM modulations in the first and / or second reception channel. It is furthermore possible to use the same path F1 dedicated to one (see both) modulation (FM or AM) for the two reception channels.

In this way, it is possible to obtain a second tuner dedicated to modulation

AM only from the first tuner. It may be noted that it is easy to propose this type of solution at present because of the existence of systems called "IF Digital" in which the AM (or FM) signal is digitized at its intermediate frequency and is then demodulated.

However, the advantage of using different paths F1 for each of the modulations is that it is possible to implement different filtering for each of these modulations and thus make it possible to avoid the "in-band" desensitization well known in the art. 'Man of the Occupation. For example, the filter for AM modulation must have a few kHz bandwidth while the filter for FM modulation must have a few hundred kHz bandwidth.

Thus, the invention makes it possible in particular to implement a "double AM" function (listening to two AM stations at the same time, for example for a "front seat / rear seat" application) and possibly to propose to the customer a "AM" function. living band "(permanent search of AM stations behind the listening station).

Claims

A car radio comprising at least a first reception channel and a second reception channel, each compatible with a first and a second type of radio modulation, the first reception channel comprising a first reception antenna (211) compatible with a first reception channel type of radio modulation and first filtering means (213) dedicated to the first type of modulation and connected to the first receiving antenna (211), the first reception channel dedicated to the processing of the first type of radio modulation being common with the second reception chain characterized in that it further comprises connection means (28) for an output of the first filtering means (213), dedicated to the first type of modulation, to an input of a mixer

(225) dedicated to said first type of modulation and belonging to the second reception channel.

2. Car radio according to claim 1, characterized in that said connection means comprise means for direct connection between: a mixer dedicated to the first type of modulation and belonging to the first reception channel; and

a mixer dedicated to the first type of modulation and belonging to the second reception channel.

3. Autoradio according to claim 2, characterized in that said connection means comprise capacitive connecting means (C32, C42, C52) for establishing an alternative connection between:

a mixer dedicated to the first type of modulation and belonging to the first reception channel; and

4. Autoradio according to any one of claims 1 to 3, characterized in that an intermediate frequency path dedicated to the first type of modulation of the first receive channel is merged with an intermediate frequency path dedicated to the first type of modulation of the second reception chain.

5. Autoradio according to any one of claims 1 to 4, characterized in that the first and second types of radio modulation belong to the group comprising:

- amplitude modulations;

- frequency modulations.