Radio receiver tester

0001The innovation relates to a device for measuring the reception quality of a time signal radio signal intended for radio clocks according to the preamble of claim 1.

0002More and more utility clocks, but also time switches are nowadays manufactured as radio clocks. These have an antenna and a radio receiver with which they can receive the time signal radio signal from the long-wave transmitter DCF 77, which is located near Frankfurt am Main and transmits with a range of over 1,500 km. From the signal of this transmitter, the date and especially the current time can be determined to the second. So radio clocks always show the right time and pose z. B. also automatically changes from winter to summer time.

0003With stationary radio clocks (e.g. wall clocks or permanently installed time switches or control clocks), the problem arises of positioning the antenna so that the radio reception is as good as possible. Radio shadowing or interference from a large number of electrical devices (e.g. televisions, computers) can impair the reception of the time signal radio signal in such a way that proper operation of the radio clocks is not possible.

0004In today's customary watches, therefore, a display is provided if the time signal radio signal could not be correctly evaluated due to interference or due to poor reception quality. The user must then search for a new location for this radio clock.

0005Furthermore, reception testers are known in which the field strength of the received radio signal is displayed. An analog output of the receiver is used, which delivers a so-called field strength proportional (RSSI: relative signal strength indicator). The disadvantage of these reception testers is that only the size of the field strength of the received signal is displayed, regardless of whether a disturbance (e.g. by television, computer, data line, jamming device, disruptive defect devices), which delivers field strength, but interferes with the time signal radio signal or even makes it illegible. Thus, these reception testers are not well suited for measuring the quality of the time signal radio reception.

0006Starting from this prior art, the innovation is based on the task of proposing a radio reception tester which measures the reception quality of the time signal radio signal and displays it.

0007This object is achieved by a device with the features of claim 1. Further developments and embodiments result from subclaims 2 to 5.

0008In addition to the receiver, the proposed radio reception tester has a signal processing stage which analyzes the time signal demodulated by the receiver and uses this to determine the signal-to-noise ratio. This signal-to-noise ratio is a measure of the quality of the radio signal received and is displayed by suitable display means.

0009The signal processing stage is preferably formed by a microprocessor. In an equally preferred embodiment, the demodulated radio signal is compared in the signal processing stage with an ideal target signal, which is stored in a memory, and the signal-to-noise ratio of the received radio signal is determined from this comparison.

0010In a further development, the display means are designed such that the signal-to-noise ratio is displayed in an analog and / or multi-stage digital display. The display means are preferably formed by a plurality of light-emitting diodes, with all light-emitting diodes lighting up with very good reception, but the fewer light-emitting diodes lighting up, the poorer the radio reception. It is preferably provided that the light-emitting diodes which indicate good reception emit green light, the yellow which indicates poor reception and the dead light which indicates poor or no reception.

0011In the following, an embodiment of the innovation will be described in more detail with reference to the drawing. The single figure shows a block diagram of the proposed reception tester.

0012An antenna 1 receives the time signal radio signals 2 from the long-wave transmitter DCF 77, not shown. The received radio signal reaches a receiver 3. The reception of a radio signal is indicated by the lighting of a (green) LED 4. Furthermore, the radio signal is demodulated in the receiver 3. The demodulated time signal arrives in a microprocessor 5, which serves as a signal processing stage. The microprocessor 5 has a non-volatile memory 6, in which an ideal target signal is stored. The demodulated time signal is compared with this ideal target signal and the signal-to-noise ratio of the received time signal is determined from this comparison. These processes take place in the microprocessor 5.

0013Depending on the size of the signal-to-noise ratio, which is a measure of the quality of the received signal, the microprocessor 5 in the display unit 7 controls several light-emitting diodes 8, 9 and 10 differently. This control is carried out in such a way that if the<img file="EP1079554A2_D0001.tif" />unreadable "reception only the red LED 10 burns, whereas in the case of poor reception, in which bit errors would occur in the evaluation of the time signal, one or both yellow LEDs 9 additionally light up and, if the reception is satisfactory to very good, one or all green ones Light-emitting diodes 8 light up. In this way, the quality of the received time signal radio signal can be displayed in six stages.

0014The electrical energy required to operate the radio reception tester is supplied by a battery 11, to which the receiver 3, the microprocessor 5 and the display unit 7 are connected via power lines 12. Furthermore, a switch 13 is provided with which the radio reception tester is put into operation. This switch is designed as a pressure switch so that the radio reception tester remains switched on only as long as the switch 13 is pressed.