Patent Application
20070042739
1. Field of the Invention
The invention concerns a process for selective testing of receiver antennas in a multi-antenna system, which are coupalable and/or coupled to a receiver via a diversity circuit, as well as a corresponding diagnostic device.
2. Description of Related Art
In contrast to geographically fixed home reception, mobile radio reception, in particular in motor vehicles, has the disadvantage that line-of-sight transmission seldom exists, and further, the field-strength at ground level is significantly weaker than the field strength as received by domestic rooftop mounted antennas. For these reasons disturbances in mobile radio reception may occur even in reception areas with good coverage. The cause for the disturbance in reception is primarily attributable to multi-path reception, caused by reflection, scattering and bending of the radio waves in the environment of the receiver, or the multi-path reception leads to delayed time differential among the partial waves, and in particular leads to interference. In addition, there are general disturbances and signal level fluctuations.
For minimizing these disturbances, antenna-diversity-systems were developed. In these systems multi-receiver antennas are employed in place of a single antenna, so that the probability is high that at least one of the receiver antennas is in a location which is not, or is less, influenced by the disturbances. A diversity switch accomplishes that, from the available receiver antennas, the receiver antenna having the least disturbance is selected to provide the received signal to the receiver. Thereby, in comparison to the conventional mono-antenna systems, an effective reduction of the diverse occurring disturbances is made possible.
A practical problem in the utilization of antenna-diversity-systems is comprised therein that the diversity circuit does not support a targeted selection of individual antennas, and accordingly the individual antennas cannot be tested for their functionality after installation.
In order nevertheless to be able to carry out a testing of the functionality of the antennas, the antenna amplifier module could, for example, be opened and the received signals of the antennas be directly sampled. This alterative is however not realistic is practice. A further possibility would be to introduce a test signal directly into the antenna line. This however fails in practical application, since access to the antenna line is mechanically not possible, in particular when the receiver antennas are adhered to the windshield of a vehicle. Alternatively, the test signals could be directly locally introduced into the various antenna branches, for example in that a part of the antennas are covered with a screen or template. In practice however this process is difficult to realize due to the bleeding of the test signal from one antenna branch to another antenna branch.
In the publication DE 199 30 571 A1 a diagnostic device for a multi-antenna system is proposed which makes it possible to carry out a differentiated testing of the individual antennas of the multi-antenna system without direct intervention in the circuitry of the receiver equipment. A proposed diagnostic device includes a control unit, which produces a control signal, which is a IF-signal (intermediate frequency signal) which will be referred to in the following as IF-control signal. This IF-control signal is supplied to the diversity circuit in place of the normal IF-signal of the receiver. By imposing a simulated disturbance on the IF-control signal it is brought about, that the diversity circuit carries out a relay switching to the next antenna in sequence. Parallel to this, a test unit is used to supply a test signal to the antennas of the multi-antenna arrangement and the received data of the respective switched to antennas are individually measured and evaluated.
The invention is concerned with a task of providing an alternative process for testing of multi-antenna systems as well as a corresponding diagnostic device.
This task is solved by a process for selective testing of receiver antennas (antenna 0 . . . 3) in a multi-antenna system (6) which is controlled by a diversity circuit (10) and couplable and/or coupled to a receiver (8), wherein the receiver antennas (antenna 0 . . . 3) are irradiated with a test signal (17), which includes a first signal progression segment, which causes a switching of the receiver antennas (antenna 0 . . . 3) by the diversity circuit (10), and includes a second signal progression segment, which impedes a change in selection of the receiver antenna (antenna 0 . . . 3) by the diversity circuit (10), and by a diagnostic device (1) for selective testing of receiver antennas (antenna 0 . . . 3) in a multi-antenna system (6), which is controlled by a diversity circuit and couplable and/or coupled to a receiver (8), the diagnostic device (1) including a transmitter unit (2) having circuits and/or programming adapted to emit a test signal (17) which includes a first signal progression segment, which triggers a switching of receiver antennas (antenna 0 . . . 3) via the diversity circuit (10), and includes a second signal progression segment, which impedes switching of the receiver antennas (antenna 0 . . . 3) via the diversity circuit (10). Advantageous embodiments are set forth in the characteristics of the dependent claims.
The inventive process is carried out in order to individually test received signals in a multi-antenna system, wherein the coupling of the receiver antennas to a receiver is controlled via a diversity circuit. The receiver antennas are preferably arranged as adjacent receiver antennas in a motor vehicle, which are, for example, integrated in the motor vehicle rear window. The receiver antennas are used to receive for example radio or television signals, alternatively the antenna system can be for WLAN-Accesspoints, GSM- or UMTS-Receiver Stations.
In particular, the multi-antenna system and/or the receiver is designed for receiving FM signals. Preferably, the diversity circuit switches through to the receiver the respective receiver antenna, of which the received signal exhibits the least disturbance and/or the best receiver characteristic.
It is envisioned that the receiver antennas are irradiated with the test signal, wherein the test signal is in particular transmitted wirelessly to the receiver antennas. The test signal is preferably produced in a diagnostic device (1) for selective testing of receiver antennas (antenna 0 . . . 3) in a multi-antenna system (6), which is controlled by a diversity circuit and couplable and/or coupled to a receiver (8), the diagnostic device (1) including a transmitter unit (2) having circuits and/or programming adapted to emit a test signal (17) which includes a first signal progression segment, which triggers a switching of receiver antennas (antenna 0 . . . 3) via the diversity circuit (10), and includes a second signal progression segment, which impedes switching of the receiver antennas (antenna 0 . . . 3) via the diversity circuit (10). Preferably the radiation is carried out in a shielded test space, so that the test signals do not influence radio reception in the environment.
The test signal includes at least a first and a second signal progression segment, which are preferably directly subsequent in the test signal. The first signal progression segment is therein designed such that the diversity circuit is forced to switching the receiver antennas. The second signal progression segment is in contrast so designed, that a switching of the receiver antenna by the diversity circuit is inhibited. Thus, conditions are produced in or on the diversity circuit, which bring about a maintenance of the actual switch condition.
The advantage of the invention lies above all therein, that all branches, that is, all receiver antennas, of a multi-antenna system equipped with a diversity circuit can be tested reproducibly and contactlessly and in particular without having to intervene in the antenna module.
In a preferred embodiment, the process is applied to a multi-antenna system with a scanning-diversity-circuit. In this type of circuit, all receiver antennas of a multi-antenna system access a single common receiver. This type of circuit is most widely employed and can be most economically produced by manufacturers. By targeted search processes the receiver antenna with the best receiver characteristic is switched or patched through to the receiver.
In a preferred embodiment of the process it is envisioned that the test signal is an unmodulated carrier signal. Preferably the frequency of the carrier signal is within a frequency range, in which the multi-antenna system is later employed. In particular the frequency of the carrier signal for receiver antennas, which are later used as radio antennas, is between is 50 and 150 MHz.
In a preferred embodiment of the process it is envisioned that the first signal progression segment of the test signal exhibits an interruption in signal level, or the test signal is reduced relative to a starting level. This collapse in level is preferably so selected with regard to its strength and duration, taking into consideration the employed diversity circuit and its coupling with the receiver, that the diversity circuit in the case of a collapse in the level recognizes a disturbance and switches to the next receiver antenna. Additionally, it can be provided that the collapse in level, in particular the duration of the collapse in the level of the signal, is so selected, that the diversity circuit switches to precisely one subsequent receiver antenna.
The process is advantageously so designed, that the second signal progression segment exhibits a level increase relative to the starting signal level. The increase in level is preferably so selected with respect to its duration and level that, taking into consideration the employed diversity circuit and its connection with the receiver, the diversity circuit evaluates the signal quality as “sufficient” and maintains the actual condition of switching. In particular, the increase in level is selected to be so strong that the switch condition of the diversity circuit is maintained even in the case of a defective receiver antenna.
In a preferred further development of the process the increase in level is in particular designed to be exponentially decreasing and/or the test signal again reaches its starting level after a defined relaxation time. Preferably, the relaxation time is longer than the duration of the signal level collapse.
In an advantageous embodiment of the process an FM-audio impulse is modulated upon the carrier signal during the first signal progression segment and/or overlapping therewith. A variety of commercially available diversity circuits check the received level and/or the presence of high frequency components in the demodulated audio signal of the signal supplied to it, for evaluation of the receive characteristic of a receiver antenna. Stated another way, the received de-modulated audio signal is examined for interference noises (noise) or impulse tips (spikes). The modulated audio impulse is designed in such a manner, that the demodulated audio impulse can be recognized by the diversity circuit as defective.
The present task is further solved by a diagnostic device (1) for selective testing of receiver antennas (antenna 0 . . . 3) in a multi-antenna system (6), which is controlled by a diversity circuit and couplable and/or coupled to a receiver (8), the diagnostic device (1) including a transmitter unit (2) having circuits and/or programming adapted to emit a test signal (17) which includes a first signal progression segment, which triggers a switching of receiver antennas (antenna 0 . . . 3) via the diversity circuit (10), and includes a second signal progression segment, which impedes switching of the receiver antennas (antenna 0 . . . 3) via the diversity circuit (10). The diagnostic device inventively includes a signal provider, which preferably is a transmitter antenna, for transmitting a test signal, as defined above.
The diagnostic device is advantageously further provided with a signal recording unit, which includes a control unit, which is coupled with the transmitter unit and at the same time is couplable and/or coupled with the receiver and/or the diversity-circuit. With the signal recording unit it is possible in the measurement operation to simultaneously record and/or evaluate the test signal and the system response of the multi-antenna system to the test signal. Further, it is able to reset the receiver to a predetermined antenna, as well as to control the transmission of the test signal and thereby to activate or deactivate this.
Further details, features, combinations of characteristics, and advantageous effects attributable to the invention can be seen from the following description of a preferred embodiment of the invention and from the figures. These show respectively in schematic representation:
Elements corresponding to each other are assigned the same reference numbers in the figures.
On the right side of
The HF (high frequency) signals coming from antenna 0 are relayed via the antenna switch 7 to a receiver 8, which produces therefrom, in known manner, an IF (intermediate frequency) signal and transmits this to the diversity circuit 10.
The diversity circuit 10 in
The diversity circuit 10 checks, by evaluation of the IF-signal, whether a collapse in level or an audio interference exists. In the case that this type of disturbance is present and therewith satisfies the condition for a bypass switching of the receiver antenna 0 . . . 3, the diversity circuit 10 switches the antenna selector switch 7, beginning from a reference antenna, over to a switch position so that then in
The signal recording unit 4 is switched in such a manner that the signal level |ZF| and/or the audio signal is detectable by ear. The signal recording unit 4 can optionally record and/or evaluate additional signals of the multi-antenna system 6 for checking or testing. The signal recording unit 4 undertakes a synchronization of the test signal with the test and evaluation signal to be evaluated.
In operation, that is, during checking of the multi-antenna system 6, the test signal is transmitted wirelessly from the transmitter antenna 3 of the transmitter unit 2 to the receiver antenna, namely antenna 0 . . . 3.
The production, design and effect of the test signal is explained on the basis of
The progression of the transmitter level of an exemplary test signal 17 is shown on the upper right of
It can supplementally be provided, that during the collapse in the level, the test signal 17 can supplementally be modulated with an FM-audio-impulse, as was described in association with the signal generator 13, in order to make possible a reliable switching over. The duration of the FM-audio impulse could be, for example 10-50 μs.
Now that the invention has been described, We claim:
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2005 039 526.0 | Aug 2005 | DE | national |
