Abstract:
The invention relates to a receiver system for vehicles having an antenna and a receiver with an interference signal receiving device. This interference receiving device comprises a coupling element with an input for taking up the pulse-like interference radiation emitted by the vehicle aggregates and which interference radiation emitted by the vehicle aggregates and which interfere with the reception, with an evaluation circuit for presenting the interference radiation. A controllable transmission element is disposed within the receiver between transmission elements. Controllable transmission element is controllable with respect to its transmission behavior for the purpose of signal sampling, which also receives output signals of evaluation circuit so that during the duration of the interference pulses, the interference pulses interfered with receive and sample usable signals. The coupling element is configured and positioned within the vehicle so that its output signal contains the pulses of the interference radiation which lead to the reception interference, and the component of the receiving usable signals is considerably low.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The invention relates to a receiver system for vehicles having a circuit for suppressing the receipt of an interference radiation emitted by these vehicles. 
     2. Description of the Prior Art 
     The interference radiation emitted by the vehicle body often leads to a considerable lowering of the quality of the receipt in the on board receiver system. Particularly in the range of the receipt of the middle and short wave (AM range) radio waves, the radio receipt is often strongly affected by audible pulse-like interferences. 
     Often the ignition system and digital components create a series of high intensity high frequency component radio waves that are received via an antenna and sent into a receiver. These radio waves are of such intensity that the antenna cannot be attached in the vicinity of the engine, or respectively any means causing strong interference radiation is not possible. In the praxis of automobile construction, by arranging the conduits or the input of means avoiding interference, it has been shown that the suppression of an interference emitting radiation through these measures is often not feasible or only feasible with high cost. 
     Thus, antenna systems for vehicles with front wheel engines are now disposed in the rear region. This is done to attain an improved interference distance with the aid of the larger distance from the main interference source. However, vehicle interferences are often so intensive that even in the case of antennas that are arranged away from the interference source, there is still noticeable interference. 
     In German Patent 24 60 227.5 there is shown a proposed solution to present vehicle interference with respect to the amount of phase in the HF range with the aid of control system and in superposition to the receiver signal of the receiver system. This receiver system is affected by the interference in that manner that the interference components in the receiver signal are cancelled. This method is very cost intensive and relies on the precise evaluation of the interference effective in the receiver antenna which is in many cases impossible. 
     SUMMARY OF THE INVENTION 
     Therefore, one object of the invention is to provide an effective and cost efficient arrangement so as to reduce the interference to render inaudible the receiver interferences which are associated with the interference radiation emitted by the entire vehicle, particularly in the frequency bands of amplitude modulated radio. 
     This aim is solved in accordance with the invention in a receiver system for vehicles. With the present invention, there is an advantage in that the determination of the time intervals, within which a series of received usable signals must be sampled. In this way, the interference from an interference radiation is not passed through the terminus device and is not determined in the received usable signals. The essence of the invention resides in that with the aid of one or more coupling elements, the interference radiation is taken up separately, and the signal corresponding to the received usable signals is rather small. 
     Thus from this invention it is possible to configure the shortest possible sampling time through the sampling of the received usable signals so that the interference is as small as possible. In the praxis it shows that there is often appreciable interference so that even with a strong received usable signal and a weak interference signal, interference free reception is rare. This applies particularly in periods when there is electrical ignition or when there are pulses of digital signals and especially in the AM radio range. Accordingly the invention is aimed to determine the time intervals of the appearance of pulse-like interferences, separated from the received usable signals, and to determine the sampling time points and the duration of sampling in accordance with the invention. 
     This is done with the aid of an interference signal receiving device. In addition there is also a coupling element for the uptake of the pulse-like interfering interference radiation emitted by the entire vehicle. Thus, the coupling element is positioned in the vehicle in such a manner and configured in such a way that its output signal predominantly contains the pulses leading to receiving interference of the interference radiation, wherein a component of the received usable signals is low so that the ratio of the component of the receiving usable signals over the interference beam is at least 10 dB lower than the output of the antenna over the interference beam. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Other objects and features of the present invention will become apparent from the following detailed description considered in connection with the accompanying drawings which disclose several embodiments of the present invention. It should be understood, however, that the drawings are designed for the purpose of illustration only and not as a definition of the limits of the invention. 
     In the drawings wherein similar reference characters denote similar elements throughout the several views: 
     FIG.  1 . shows a block diagram of the first embodiment of the receiver system; 
     FIG. 1 b  shows a block diagram of an additional embodiment of the invention further comprising sampling device; 
     FIG. 2 shows a block diagram of another embodiment of the invention wherein the evaluation circuit further comprises a reference level and a logic circuit; 
     FIG. 3 a  shows a block diagram of another embodiment of the invention wherein the evaluation circuit comprises a bandpass filter; 
     FIG. 3 b  is a block diagram of the band pass filter having a low frequency component and a band width having a middle frequency; 
     FIG. 4 shows a block diagram of an additional embodiment of the invention further comprising a receiver circuit; 
     FIG. 5 shows a block diagram of another embodiment of the invention wherein the evaluation circuit comprises a logic circuit; 
     FIG. 6 shows a block diagram of another embodiment of the invention wherein the antenna is configured as a controllable transmission element having a sampling device; 
     FIG. 7 shows a block diagram of another embodiment of the invention wherein the antenna has an antenna amplifier, and a transit time element with a post connected controllable transmission element; 
     FIG. 8 shows a block diagram of a receiver having a controllable transmission element and an interference signal receiving device having a sampling device and a transit time element; 
     FIG. 9 shows a block diagram of the receiver system having a signal receiving device with a sampling device in the range of a low frequency component of the receiver; 
     FIG. 10 a  shows a receiver system having an electrical coupling conductor disposed at a suitable distance; 
     FIG. 10 b  shows a coupling element that is in the vicinity of the window frame; 
     FIG. 10 c  shows a coupling element showing a series of capacitors and also shows the electrical and magnetic fields associated with these capacitors; 
     FIG. 11 shows an additional embodiment of the receiver system having a matrix circuit; and 
     FIG. 12 shows another embodiment of the receiver system having a level indicator and a level evaluation circuit for control of the sampling time and the sampling depth through adjustment of the reference level and the logic circuit. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     FIG. 1 refers to a receiver system having a receiver  2  connected to antenna  1 , and connected to an interference signal receiving device  29 . Receiving device  29  comprises a coupling element  3  and an evaluation circuit  4 . Evaluation circuit  4  is for the generation of a sample signal  7  when the receiver system receives an interference signal  11  from vehicle  20 . 
     In a first, simplified embodiment, a controllable transmission element  6  is contained in a interference signal receiving device  29 . Interface signal receiving device  29  also contains transmission elements  5  connected to and disposed adjacent to controllable transmission element  6 . In this case, when sample signal  7  is introduced into transmission element  6 , it blocks transmission of interference radiation  11  from passing on to terminus device  25 . This sampling can be carried out as full sampling over a fixedly adjusted time interval. In this case, there is a congruent time interval between the occurrence of the interference in a series of received usable signals  16 , and sample signals  7 . 
     When the sampling time is longer than the occurrence of the interference in the received usable signal  16 , there is unnecessarily large and unavoidable interference. However, when the sampling time is smaller than the occurrence of interference in the received usable signal  16 , the interference in the receiving usable signal is not fully ineffective. To overcome this discontinuity in time intervals, the receiver can be configured to reduce interference by means of sampling techniques such as soft sampling with time wise polished transitions, having appropriate sampling depth which is limited taking back of the transmission characteristics in controllable transmission element  6 . In addition other techniques such as sample and hold techniques whereby the momentary value of the received usable signal  16  during the sampling time is held at the last value. 
     FIG  1   b  shows a second embodiment of the receiving system wherein the interference signal receiving device  29  is integrated in a housing with receiver  2 , with separated input connections for antenna  1  and coupling element  3 . In addition in this embodiment there is shown sampling device  19  disposed within controllable transmission element  6 . Sampling device  19  is for receiving sample signals  7  from evaluation circuit  4 . 
     As shown in FIG. 2, interference radiation  11  is received via coupling element  3  and i s evaluated in a broad band manner. To start the sampling process in evaluation circuit  4 , there is a comparing logic circuit  10  with two inputs disposed with in evaluation circuit  4 . The first input is connected to the interference radiation level  13 , which is compared with reference level  9  at the other input. When reference level  9  is exceeded by interference radiation level  13  at the exit of logic circuit  10 , sample signal  7  is generated which effects the sampling process in controllable transmission element  6 . 
     When there are time wise pulse forms which have only relatively low signal components in the frequency range of receiver  2 , the sampling interval is often too long and not optimally placed time wise. Because the invention offers a substantial improvement the frequency band width is narrowed in interference radiation signal receiving device  29 . This result is obvious from FIGS. 3 a  and  3   b . In this design, there is a band pass filter  8 , that is post connected to coupling element  3 . Band pass filter  8  is adjusted, with its middle frequency  41 , wherein its band width  22  is selected to be sufficiently large so that the indicated interference radiation level  13  is largely representative of the interference arising in the receipt channel of receiver  2 . A further possibility exists therein to configure the band width  22  of band pass filter  8  nearly congruently with that frequency range wherein receiver  2  can be adjusted. 
     As shown in FIG. 4, the signal band width in interference signal receiving device  29  is adapted to the channel band width of receiver  2 . This will ensure that sample signal  7  is present only due to those components in interference radiation  11  which can lead also to interferences in the receiver, and thereby, in terminus device  25 . Thus, the sampling time is limited to the lowest extent required. Oscillator  24  of receiver  2  is used with the superposition principle to ensure the adjustment of the interface signal receiving device to the present receipt channel of receiver  2 . As shown in FIG. 4, controllable transmission element  6  contains sampling device  19  which is disposed adjacent to receiver ZF component  26  but ahead of receiver demodulator  27 . Interference radiation  11  is read by coupling element  3  which then presents signals that are converted in interference signal mixer  12  to the intermediary frequency plane and limited in their band width with the aid of an intermediary frequency filter  14 . With the aid of a demodulator circuit  17 , the interference radiation level  13  is won and passed to logic circuit  10  and next processed. 
     Now controllable transmission element  6  is disposed behind receiver ZF component  26  in the sequence of the transmission elements  5 . Thus, the one advantage of the receiver system is that because of band limitations in the receiver  2  and the arising delays are similar in the interference signal receiving device  29 , only small differences in transit time arise. Thus, the sampling intervals of the signals arise approximately nearly fully time wise with the pulse-like interferences in the receiving usable signal  16 . 
     In another embodiment of the invention, as shown in FIG. 5, the invention requires that the logical signal experiences retardation at the exit of logic circuit  10  due to band limitation. This occurs through inclusion of a transit time element  15  in sequence with transmission elements  5  in receiver  2  which is adjusted prior to controllable transmission element  6 . This type receiver is shown in FIG.  5 . Thus, the time wise placement of the sampling interval is largely congruent with the point of time of the appearance of the interference in the receiving usable signal  16 . 
     It is common in the automotive industry for receiver devices to be included within the production of the auto. Unfortunately, in many cases, because of requirements, different vehicle series may not permit the integration of an interference signal receiving device  29 . For these cases, it is possible in another embodiment of the invention to configure the interference signal receiving device  29  by utilizing serially manufactured receivers  2 . A receiver system of this type is shown in FIG.  6 . In this embodiment, antenna  1  is configured as controllable transmission element  6 , which contains sampling device  19  which receives sample signal  7 . The interference signal receiving device  29  can thereby be arranged in the vicinity of antenna  1  in the vehicle, or respectively can form a component unit with antenna  1 . 
     FIG. 7 shows a receiver system of this type wherein antenna  1  is formed as an active antenna with an antenna amplifier  28 . The configuration can thereby be by way of sampling the interior amplification of the active antenna with the aid of controllable transmission element  6 . Because of the limitation of the band to band width  22  of band pass filter  8 , there must be a corresponding transit time element  15 , in the signal train of the active antenna. 
     FIG. 8 shows that the transit time element  15  is included in the signal branch of the interference signal receiving device  29  to improve the congruency of the time wise positioning of the sampling interval with the point of time of appearance in the interface in the receiving usable signal  16 . As shown in FIG. 9, transit time element can be placed at the exit of logic circuit  10  to retard the signal whereby the sample signal is retarded by the required time difference. 
     To achieve a rather large ratio of interference radiation level  13  to receiving usable signal  16 , coupling element  3  which receives interference radiation  21  should be configured to a coupling conductor  32  and arranged in the vicinity of antenna  1 . However, coupling conductor  32  is configured so that its electric-magnetic coupling to the body of vehicle  20  is substantially greater than the unavoidable coupling of antenna  1  to the body of vehicle  20 . In addition, the associated coupling of coupling element  3  to the free space is substantially smaller than that of antenna  1 . With this design, the intakes of the vehicle bound interference radiation  11  of coupling element  3  and of antenna  1  are similar to one another. In addition, the interferences of the receiving usable signal can be sampled in an aimed manner. Embodiments of coupling element  3  of this type are represented in FIGS. 10 a, b , and  c . Coupling element  3  is comprised of coupling conductor  32  with a co-coupling circuit  33  respectfully. In FIG.  10   a  coupling conductor  32  is configured so that it receives interference radiation  11  as electrical field strength E. In FIG. 10 b , however, coupling conductor  32  is configured as magnetic loop  32   a  for receiving interference radiation  11  as magnetic field strength H. In FIG. 10 c , there is shown both magnetic loop and electrical loop  32   b  for receiving interference radiation  11  as both magnetic field strength H and electrical field strength E. 
     Coupling conductor  32  is arranged in the vicinity of window frame  42  because of the high concentration of the electrical and magnetic fields of interference radiation  11  in an immediate vicinity of window frame  42 . The superposed uptake of electrical and magnetic field components of interference radiation  11  is done with the aid of coupling conductor  32 . This embodiment is shown in FIG. 10 c  wherein both ends are subjected to capacitive loading. Electronic element  43  in coupling circuit  33  forms with its input capacity of less than 50 pF between control electrode  44  and the source electrode  45  the capacitive load. The exit tension of electronic elements  43  contains both magnetic and electrical field components of interference radiation  11  effected components. 
     FIG. 11 shows a coupling element  3  for co-coupling with immediate inductive coupling at conductor  34  which carries interference current. In a similar manner, coupling element  3  is represented as capacitive coupling at a conductor  35  which carries the interference tension, at the vehicle  20 . With the aid of matrix circuit the signals of several coupling elements  3  emanating from different interference sources, are superposed in a linear and weighted manner. Such a matrix circuit can be realized as a resistence network. The exit signal of matrix circuit  31  is passed to evaluation circuit  4 , when there is correct weighting of the individual interference causes, the interference components of such causes can be effectively sampled in the receiving usable signal. 
     In reception situations in which there is a sufficiently large level of the receiving usable signal  16  it is advantageous to not utilize the sampling process because the interference components due to the interference radiation  11  do not take effect as receiver interferences. This will fully preclude remainder interferences, which could be associated with the sampling per se. Received usable signals  16  have an interference region which is between dominant pulse like receipt interferences, with complete sampling and negligible pulse like receipt interferences without sampling, so that the sampling depth is shown as a function of the level. 
     In FIG. 12, in receiver  2 , the signal level is passed to a level indicator  38  and evaluated in a level evaluation circuit  39  with respect to the sampling time and the sampling depth. Through adjusting of reference level  9  and logic circuit  10 , a suitable sampling time and suitable sampling depth is adjusted. 
     In a simplified embodiment, especially exhibiting the least number of components in the logic circuit  10 , the ratio of level of receiving usable signal  15  to the interference radiation  13  is determined. When occurring below a threshold value, the controllable transmission element  6 , through activation with the aid of sample signal  7 , controls a low frequency component so that during the time interval of sampling, the present receiving usable signal is blocked at its output. However, the last value prior to commencement of the sampling is present in a sample and hold situation. 
     Accordingly, while several embodiments of the present invention have been shown and described, it is to be understood that many changes and modifications may be made thereunto without departing from the spirit and scope of the invention as defined in the appended claims.