FI94303C - Device for receiving signals transmitted on the basis of a UIC standard in vehicles, in particular rail vehicles - Google Patents

Description

94303

The invention relates to a location-separate, transceiver of a mobile transmission signaling device 10 of a vehicle U, mostly connected to the rails, arranged in a fixed manner along a given path. (International Union of Railways). The transmission of signals to the mobile transceiver takes place in such systems from successive transceivers at varying even transmission frequencies, each mobile transceiver being tuned to the best receivable signal, which in most cases has the transmission frequency of the nearest transceiver station.

The signal quality evaluation criteria are 20 e.g. noise distance and / or received field strength (noise evaluation or field strength evaluation). Until now, there is only one frequency-changeable in conventional transceivers. transmit-receive channel, and start the unsatisfactory interval with the value of the evaluation criterion in the search period (scanner principle) until a transmission frequency is found which achieves a satisfactory signal quality. However, due to time considerations, it is often omitted to test whether this frequency is actually the most advantageous of the transmission frequencies available at a given reception location.

It takes about 30 to 100 ms to switch to the new signal frequency and evaluate the signal quality. For systems with a longer monitoring time of 35 (eg approximately 1 2 94303 s in accordance with UIC recommendation E 1.13.2), this time can be up to two seconds. Such monitoring and switching times are generally not tolerable. Namely, in systems using data transmission (the typical length of a data message is about 100 ms), the messages may be lost either completely or at least in part. These messages should be sent repeatedly, which would lead to additional system load (poor channel utilization). Whole bytes could be lost in voice transmission, which in the case of unfamiliar users would lead to repeat requests and thus longer call times.

Alternatively, in order to eliminate the described deficiencies, the described monitoring time could be shortened, the switching criterion selected as very low and the field strength selected above the necessary level in the operating range.

15 By shortening the monitoring and switching time, UIC standards cannot always be met and the criteria for evaluating signals become very uncertain. In the case of local excessively long, mostly geographically and regionally very limited coverage distances, the channel is then changed unnecessarily often. In this case, it is no longer possible to ensure the optimal accessibility of the mobile transceiver.

If, on the other hand, the switching criterion is chosen well; low, the mobile transceiver remains as long as possible at the currently selected signal frequency, even if a substantially more favorable frequency is already available.

Finally, higher field strengths naturally result in greater interference dimensions. Separate .30 signal frequencies can only be reproduced over very long distances, making poor use of them.

The invention now relates to a device for receiving signals transmitted at location-varying transmission frequencies 35 in accordance with the UIC standard in vehicles, # QA 7. η Ί 7 -ruu 0 3, in particular in rail-bound vehicles, using evaluation stages to select the most advantageous transmission frequency in each case, the shortcomings described above, in particular the interfering switching times, 5 automatically allow for optimal signal reception at all times.

This object of the invention is achieved in that the input part of the receiver is designed to be wideband for all received signal frequencies, that bandpass filters are previously provided to divide the previously changed frequency frequencies into separate channels and in this connection separate mixing stages for different frequency frequencies - and demodulator stages for these modified signal frequencies, and that one output of each amplifier and demodulator stage is immediately connected to a noise estimation stage with a digital output signal and / or a field strength estimation stage with a digital output signal for selection.

. Since the receiver of the mobile transceiver according to the invention receives, demodulates and evaluates all the transmission frequencies of the transmitting-receiving station of the path, it is known at any time which of the frequencies offers the best signal quality. Accordingly, the optimal reception frequency can be selected at any time by means of a switching matrix. Because no frequencies need to be changed when switching from one receive frequency to another, and because all channels are monitored continuously, typical switching times are less than 1 ms.

DE-A-31 09 849 discloses a switching device for automatically selecting a better received signal from two received signals. In the switching device, the audio frequency outputs of the two completely separated high-frequency receiver parts (2, 3) are led to the audio frequency amplifier part (1) via a switch (4) controlled by the level reference stage (5). The level inverter (5) indicates which receiver section receives the better signal (page 4, paragraph 2). The concrete structure of this level of comparison is not presented. The invention disclosed in DE-A-10 31 09 849 relates in particular to the fact that at least one receiver part is provided with a search run A which searches in the receiver part not connected to the audio frequency amplifier for a transmission frequency having a modulation content (= radio program) which corresponds to 15 programs received by the second receiver section. The program identity is adjusted by comparing the detected (6-8, 10-12) audio frequency output signal interruptions (14) of both receiver parts.

In principle, parallel reception with three 20 independent receivers would also be possible. However, this would require significantly higher costs, especially in the case of evenly spaced signal frequencies and with a number of channels equal to or less than 3, the oscillators of the separate receivers would have to be synchronized with respect to frequency to avoid intermodulation problems. In a particularly preferred embodiment, the receiver according to the invention avoids this cost, in particular with a first and a second mixing oscillator common to all channels. The cost of separate intermediate frequency filters required for this for all channels is relatively small in series production and technically substantially less problematic than frequency synchronization of three oscillators. An additional advantage is the partial redundancy of the overall system.

35 Since the switching matrix can be implemented as hardware, a substantially lower software cost is achieved than with receiving devices of conventional construction.

An embodiment of the invention will now be described in more detail with the aid of a drawing showing a receiving part of a mobile transceiver according to the invention.

The input signals from the interface 1 of the vehicle antenna operating in the simultaneous reception and transmission operation are passed to a duplex filter 2, which acts to separate the output signals transmitted to the vehicle antenna by the output line 3 of the mobile transceiver from its input signals. The input signals are passed from the receiver input line 4 via a preselection bandpass filter 5, e.g. a helix filter, an input amplifier 6 and a second bandpass filter 7, which may also be a helix filter, to a mixer 8, to which a carrier frequency is applied from the mixing oscillator 9 and to change to lower intermediate frequencies ZF1. When amplified in the Vt amplifier 10, the intermediate frequency input signals are applied to a signal divider 11, which conducts these signals to three parallel reception channels 12, 13 and 14. Up to the outputs of this signal divider, the entire common reception path is formed by steps 4-11 of wideband, i.e. to pass the transmission frequencies or intermediate frequencies ZF1 derived from all the transmission and reception stations arranged along the path.

Separate narrowband filters 15, 16 and 17 are connected to the output channels 12 to 14 of the signal divider 11; 30 which each emit one intermediate frequency ZF1 provided by the oscillator 9 by changing the evenly spaced signal frequencies. Taking the simple case with only three evenly spaced signal frequencies SF according to the drawing, where the frequency interval is 50 kHz, 35 and denoting the middle signal frequency ZF1 ,, ', a series ZF1B to 50 kHz, ZF1B and ZF1B according to the output frequencies 15 to 17 is obtained. + 50 kHz, from which, for example, the value ZF1B = 21.400 MHz gives the emission frequencies 21.350, 21.400 and 21.450 MHz for channel filters 15 to 17.

The intermediate frequencies ZF1 thus obtained are converted in three separate mixers 18, 19 and 20 by means of a carrier supplied from the second common oscillator 21 via a signal divider 22 and separate supply lines 23, 24 and 25 to substantially lower intermediate frequencies ZF2, 10 e.g. 405, 455 and 505 kHz.

The signals at these intermediate frequencies ZF2 are amplified and demodulated in the vt amplifiers and demodulators 26, 27 and 28. The demodulated signals, which are, for example, low-frequency analog signals, are fed directly to the signal inputs of the switching matrix 32 via output lines 29, 30 and 31.

The switching of the signal inputs of the switching matrix 32 to its signal output 45 takes place automatically in the basic task of evaluating the quality and quantity of the input signals. For this purpose, a noise estimation stage with a digital output signal (33-35) and / or a field strength estimation stage with a digital output signal (39-41) is connected to the amplifiers and demodulators 26 to 28. The evaluation stages 33 to 35: 25 and 39 to 41 lead the evaluation results in the form of digital switching signals on lines 36, 37 and 38 and 42, 43 and 44, respectively, to the control weather outputs of the switching matrix 32. Noise estimation stages that produce digital signals are known as Squelch, and likewise; 30 known are field strength estimation stages which produce digital output signals via analog / digital converters and / or comparators.

The digital signals of both types of evaluation stages 33-35 or 39-41 select qualitatively the best qualitatively input signal input to the switching matrix 29-31 in the switching matrix 32 in the switching matrix 32 known per se, and produce it at the output line 45. the receiving-conditions.

The described embodiment allows various variations within the scope of the invention. Thus, for example, intermediate frequency generation can also be performed in separate reception channels 12, 13 and 14 by three separate mixing oscillators, the frequencies of which differ from each other by the frequency range SF of the evenly spaced transmission frequencies, and which are mixed with the output frequencies of the channel filters 15-17. similar.

In addition, in the switching matrix 32, the evaluation criteria can be freely selected using programmable logic components, i.e. by forming this matrix as a programmable logic matrix, and thus adapted to the respective use case. In addition, the evaluation criteria included in the demodulated signal currently connected to line 45 can also be connected to other lines, e.g. line 46 for the noise criterion and line 47 for the field strength criterion, in order to provide additional information to the user. Finally, for monitoring, in addition to the selected signal on line 45, all: 25 other demodulated signals can be routed to through parallel reception channels.

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Claims (5)

An apparatus for receiving, according to the UIC standard, at alternating equidistant transmission frequencies, transmitted signals from locally arranged transmitting antennas in vehicles, especially rail-bound vehicles, by using estimation steps to select the currently most suitable transmission frequency. characterized in that the input portion (4 - 11) of the receiver is designed to be broadly banded for all received signal frequencies, that band filters (15 - 17) are arranged for dividing previously common to lower frequency converted signal frequencies into different channels (12 - 14) and adjoining various mixer stages (18-20) in these band filters for converting the signal frequencies of the various channels to a lower frequency as well as different amplifier and demodulator stages (26-28) for these converted signal frequencies, and an output (29- 31) in each amplifier and demodulator stage is instant and together with one with a digital output signal (33 - 35) provided a noise estimation step and / or together with a field strength estimation step coupled with a digital output signal (39 - 41) coupled to a coupling matrix (32) for selecting the currently best estimated signal for continued processing. 2. Device according to claim 1, characterized in that a common oscillator (21) is arranged for the various mixing steps (18-20). 3. Device according to claim 1 or 2, characterized in that the coupling matrix (32), in addition to the output (45), is currently the most appreciated. the signal comprises an output (46 and / or 47) of the noise estimation signal and / or field strength estimation signal. Device according to any one of claims 1 to 3, 35, characterized in that the coupling matrix (32) is a logic matrix which can be programmed to adjust the estimation criteria for different modes of use.