FR2500170A1 - RECEIVER FOR NAVIGATION SIGNALS - Google Patents

Abstract

RECEIVER FOR A NAVIGATION SYSTEM INCLUDING ANTENNA 1, AN ANTENNA FILTER 2, A BUFFER AMPLIFIER 3 AND A NUMBER OF TUNED AMPLIFIERS 4, 5, 6 AND 7. TWO BALANCED DEMODULATORS 8-1, 8-2 ARE CONNECTED AT THE OUTPUT OF EACH AMPLIFIER AND ARE EACH CONTROLLED BY TWO LOCAL OSCILLATOR SIGNALS OF OPPOSITE PHASE. THE TWO 0, 180 SIGNALS THAT COMMAND THE FIRST DEMODULATOR 8-1 ARE PHASE 90 COMPARED TO SIGNALS 90, 270 WHICH COMMAND THE OTHER 8-2 DEMODULATOR. THESE SIGNALS ARE DERIVED FROM A FREQUENCY SYNTHESIZER 12 WHICH IS CONNECTED TO A NON-SYNCHRONIZED SOURCE OF LOCAL OSCILLATOR SIGNALS 13. LOW PASS FILTERS 14, 15 ARE CONNECTED TO THE OUTPUTS OF THE DEMODULATORS. THEIR OUTPUTS ARE CONNECTED TO A SIGNAL MULTIPLEXER 16 THE OUTPUT OF WHICH IS CONNECTED TO AN ANALOG TO DIGITAL CONVERTER 17. THE OUTPUT OF THIS CONVERTER IS CONNECTED TO A PROCESSOR 18. THE PROCESSOR CONVERTS THE INFORMATION FROM THE NAVIGATION SIGNALS INTO THE POSITION INFORMATION . REPRODUCTIVE MEANS 19 GIVE POSITION INFORMATION IN LONGITUDE AND LATITUDE. APPLICATION: NAVIGATION.

Description

"Receiver for Navigation Signals" The present invention relates to a

  receiver for a navigation system having a number of spatially distributed transmitters which transmit synchronized navigation signals on at least one

  predetermined channel frequency and in a sequence of suc-

  determined transfer, this receiver comprising

  a source of local oscillator signals on said frequency

  predetermined channel and mixer means for mixing the received navigation signals with the

  signals from the local oscillator used to provide

  showing the quadrature components of the beat signal between the received navigation signals and

signals from the local oscillator.

  Such a receiver is described in the patent

  English No. 1,086,733. This receiver is intended for a

  me of radio-navigation in which a post master and

  a slave station red, green and purple emit

  and between continuous emissions on different channel frequencies by so-called multiple pulses

  which include a combination of frequency signals

  these 6F, 8F, 9F and 5F o F is a frequency in the region of 14 kHz. This known receiver receives signals on a frequency, namely the channel frequency 6F. This receiver comprises a synchronized local oscillator which is synchronized by the transmission signal of the master station

  which, except during multiple pulses, continuously emits

  on the frequency 6F a signal on which the oscillator-

can synchronize.

  The synchronization of the local oscillator com-

  plic the receiver. This complication takes on important

  when the receiver is developed not only for signals on frequency 6F, but also for

  the reception of signals on the frequencies 8F, 9F and 5F.

  The aim of the invention is to provide a receiver which does not need a synchronized local oscillator and which

  can be done in a simple way with the help of

standards.

  The receiver according to the invention is

  for this purpose in that the mixing means comprise

  Two balanced demodulators are each driven by two opposite-phase local oscillator signals that are derived from a connected frequency synthesizer.

  to an unsynchronized source of oscillator signals.

  local area, and the two signals that drive the first

  900 of the two signals which drive the other demodulator and the outputs of the demodulators are connected low-pass filters whose outputs are connected to the respective inputs of a signal multiplexer whose output is connected to an analog converter. digital whose output is itself connected to a programmable data processor for converting the information of the navigation signals to output signals representing the position coordinates of the receiver and the reproducing means for reproducing

  position coordinates under the control of these

output signals.

  The invention will be explained below in more detail with reference to a represented embodiment.

in the figure of the appended drawing.

  The receiver has an antenna bandpass filter 2 connected to the antenna 1. The antenna is actually a part of the filter which has four resonances

  for channel frequencies 6F, 8F, 9F and 5F. Frequently

  7F is a mitigation pole used to suppress

  sea signals from 100 kHz

LORAN-C.

  The amplifiers 4, 5, 6 and 7 tuned to the frequencies 6F, 8F, 9F and 5F are controlled from a buffer amplifier 3 which is connected to the antenna filter 2. The received signals can be cut in the amplifier buffer 3, to provide a zero reference to the output of the receiver. The connected amplifiers contain LC circuits which are tuned to the channel frequencies in question. Each amplifier is equipped with fast automatic intensity control

  (CAG). The AGC control in channel 6F can be reversed.

  from a fast operation to a slow operation in order to better detect in the navigation system amplitude-modulated synchronization pulses possibly occurring on the frequency

of channel 6F.

  The amplifiers tuned 4, 5, 6 and 7 are

  each connected to the mixing means (mixing devices

  8, 9, 10 and 11 respectively which are made of

  analogy, as the drawing indicates for the

  8. The latter comprises two balanced demodulators 8-1 and 8-2 which are each driven by two

  local oscillator signals of opposite phase on frequency

  this channel 6F. The signals that drive the demodulator

  8-1 are 900 out of phase with the signals

try the 8-2 demodulator.

  The signals that drive the 8-1 and 8-2 demodulators are produced by a Johnson 8-3 meter which

  is connected to the output for frequency 24F of a synthesizer

  frequency converter 12 which is driven or controlled by

  a non-synchronized source of local oscillator signals

  13. The Johnson 8-3 meter provides four out of the four outputs labeled 0, 90, 1800, and 2700, four waveform phase-shifted output signals.

  rectangular which directly control the demodulators.

  The active filters 14 and 15 connected to the outputs of the demodulators with a limit frequency of approximately 10 Hz eliminate

  output signals the unwanted frequency components

  which are due to the control by rectangular control signals and they simultaneously reduce the bandwidth of the receiver to reduce noise

to the output.

  The output signals of the mixer devices 8, 9, 10 and 11 are fed to the signal multiplexer 16

  whose output is connected to an analog converter

  17. The output of this converter is connected to a programmable data processor 18. Means

  19 and a keypad 20 are connected

to the processor 18.

  The processor controls, via the control bus 21, the signal multiplexer 16, the buffer amplifier 3 and possibly the amplifier

  4. This possible order is applied when

  that synchronization pulses modulated in ampli-

  must be able to be detected on the frequency of

channel 6F.

  The process 18 will be programmed for executing the synchronization of the receiver which can be done on the emissions of the master station by detecting the synchronization pulses in the transmission of this master station, these pulses being able to be amplitude modulated pulses or modulated pulses with phase shift

1800 on the frequency 6F.

  As soon as synchronization is obtained, the

  receiver knows when he can expect multi-pulses

  the various posts, since these are

issued in a fixed format.

  The receiver can basically work with

  only one channel, since all

  following each other a signal on a frequency

  channel, thanks to which all the information

  navigation principle is in principle entirely present in a channel. Other channel frequencies can

  used to obtain independent measurement results

  to make it possible, by combining all the measurement results, to obtain a result

final more precise.

  By means of the keyboard 20, it is possible to introduce into the processor 18 an evaluation of the position coordinates of the receiver. The processor 18 converts

  information that is provided by the analog converter

  Fig. 17, at output signals representing the actual positional coordinates of the receiver. Under

  the control of these output signals, the means of reproduction

  duction 19 give the position of the receiver in longitude

and in latitude.

  Buffer amplifier 3 may be controlled by processor 18 to provide a zero reference to

  the output of the analog-digital converter 17.

Claims (1)

CLAIM   Receiver for a navigation system comprising a certain number of transmitters distributed in space, which emit synchronized navigation signals on at least one predetermined channel frequency and in a sequence of succession in the determined time, this receiver comprising a source of local oscillator signals on said predetermined channel frequency and mixing means for mixing the navigation-received signals with the signals of the local oscillator for providing signals representing the quadrature components of the beat signal between the navigation signals received and signals from the local oscillator, characterized   in that the mixing means comprise two demodulators   balanced oscillators which are each driven by two opposite phase local oscillator signals which are derived from a frequency synthesizer connected to a non-synchronized source of oscillator-local signals and the two signals which drive the first demodulator are out of phase with each other. 900 compared to the two signals that drive the other   demodulator, and to the outputs of the demodulators are connected   low-pass filters whose outputs are connected to the respective inputs of a signal multiplexer   the output-is connected to an analog converter-   digital whose output is itself connected to a programmable data processor for the conversion of the information of the navigation signals into output signals representing the position coordinates of the receiver and the reproducing means for reproducing   position coordinates under the control of these output signals.