Automotive radio receiver with radio frequency interference elimination circuit

• US 4,584,714 A
• Filed: 06/18/1984
• Issued: 04/22/1986
• Est. Priority Date: 02/02/1982
• Status: Expired due to Fees

• Current Assignee: Nissan Motor Co., Ltd.
• Original Assignee: Nissan Motor Co., Ltd.
• Inventors: Fukuhara, Hiroshige
• Primary Examiner(s): NG, JIN FAY
• Application Number:
  US06/621,931
• Time in Patent Office: 673 Days
• Field of Search: 455/219, 455/212, 455/222, 455/223, 455/238, 455/297, 455/298, 455/307, 455/312, 381/94, 381/107, 328/165
• US Class Current: 455/297
• CPC Class Codes: H03G 3/345 Muting during a short period of time when noise pulses are detected, i.e. blanking H03G3/348 takes precedence

Abstract

An automotive radio receiver with a radio frequency interference elimination includes a noise detector adapted to detect noise in the power source wiring and a circuit for eliminating radio frequency interference noise. The detector is physically connected to the power source wiring so that it can satisfactorily detect noise in the power source wiring such as spark ignition noise and switching noise of the automotive electric equipment. The noise elimination circuit includes a switch normally closed and responsive to the noise signal produced by the noise detector to open, and a capacitor for holding the radio signal level while the switch is opened and discharging the constant-level signal for reproduction of the radio sound.

Claims

1. A radio frequency interference elimination device in an automotive radio receiver comprising:

a radio circuit for receiving radio broadcasting signal suitable for audio reproduction;

a noise detector for detecting radio frequency interference noise due to automotive electric circuits, said detector being electrically connected to power source wiring to receive radio frequency interference noise therefrom and produce a detector signal when said noise is detected;

a radio frequency interference elimination circuit disposed within said radio circuit and responsive to said detector signal to hold radio broadcasting signal level at an immediate preceeding level for a given period and outputting the held level of radio broadcasting signal for reproduction; and

wherein said noise detector comprises a diode, a delay circuit, a Zener diode and a transistor connected in sequence, said delay circuit and said Zener diode being connected to produce a constant-duration pulse signal in response to said radio frequency interference noise to turn said transistor on for said constant duration.

4. The device as set forth in any one of claims 1, 2 or 3, wherein said transistor is connected to said radio frequency interference elimination circuit to hold the radio broadcasting signal level.

5. The device as set forth in claim 4, wherein said Zener diode is connected to the cathode terminal of said diode.

2. A radio frequency interference elimination device in an automotive radio receiver with an automatic gain control, comprising:

a radio receiver circuit for receiving a radio broadcasting signal and reproducing an audio sound;

a detector for detecting a radio frequency interference noise in automotive electric circuits and producing a detector signal upon detecting said radio frequency interference noise, said detector being connected to electric power source wiring to pick up noise components therefrom, said detector being adapted to absorb relatively low frequency noise and produce said detector signal in response to relatively high frequency noise;

a radio frequency interference elimination circuit provided within said radio receiver circuit and including a sample/hold means which is normally in sample mode for sequentially sampling radio broadcasting signal inputted thereto and is responsive to said detector signal to hold the signal level of said radio broadcasting signal for a given period, said sample/hold means outputting a signal at the held level while it is maintained at said hold mode; and

wherein said noise detector comprises a diode, a delay circuit, a Zener diode and a transistor connected in sequence, said delay circuit and said Zener diode being connected to produce a constant-duration pulse signal in response to said radio frequency interference noise to turn said transistor on for said constant duration.

3. A radio frequency interference elimination device for an automotive radio receiver circuit with automatic gain control, comprising:

a radio receiver circuit including an antenna, a high frequency amplifier, an intermediate frequency amplifier, a signal detector, a voice frequency amplifier and a speaker;

a noise detector for detecting noise created in automotive electric circuits to produce a detector signal upon detecting radio frequency interference noise, said detector being connected to electric power source wiring of the automotive vehicle and adapted to detect said noise flowing through said wiring;

a radio frequency interference elimination circuit interpositioned between said signal detector and said voice frequency amplifier for sequentially sampling detector output and outputting the sampled level thereof, said radio frequency interference elimination circuit being responsive to said detector signal to hold the detector signal and output the held level thereof to said voice frequency amplifier as long as said detector signal is inputted; and

wherein said noise detector comprises a diode, a delay circuit, a Zener diode and a transistor connected in sequence, said delay circuit and said Zener diode being connected to produce a constant-duration pulse signal in response to said radio frequency interference noise to turn said transistor on for said constant duration.

6. A radio frequency interference elimination device in an automotive radio receiver comprising:

a radio circuit for receiving radio broadcasting signal suitable for audio reproduction;

a noise detector for detecting radio frequency interference noise due to automotive electric circuits, said detector being electrically connected to power source wiring to receive radio frequency interference noise therefrom and produce a detector signal when said noise is detected;

a radio frequency interference elimination circuit disposed within said radio circuit and responsive to said detector signal to hold radio broadcasting signal level at an immediate preceeding level for a given period and outputting the held level of radio broadcasting signal for reproduction;

wherein said noise detector comprises a high-pass filter and a delay circuit, said high-pass filter being adapted to absorb relatively low frequency noise and having impedance defining a cut-off frequency for relatively high frequency noise; and

wherein said noise detector varies the detector signal level depending on the noise level inputted thereto, and said radio frequency interference elimination circuit is connected to said noise detector so that it varies the cut-off frequency for holding the radio broadcasting signal level according to the detector signal level.

7. A radio frequency interference elimination device in an automotive radio receiver with an automatic gain control, comprising:

a radio receiver circuit for receiving a radio broadcasting signal and reproducing an audio sound;

a detector for detecting a radio frequency interference noise in automotive electric circuits and producing a detector signal upon detecting said radio frequency interference noise, said detector being connected to electric power source wiring to pick up noise components therefrom, said detector being adapted to absorb relatively low frequency noise and produce said detector signal in response to relatively high frequency noise;

a radio frequency interference elimination circuit provided within said radio receiver circuit and including a sample/hold means which is normally in sample mode for sequentially sampling radio broadcasting signal inputted thereto and is responsive to said detector signal to hold the signal level of said radio braodcasting signal for a given period, said sample/hold means outputting a signal at the held level while it is maintained at said hold mode;

wherein said noise detector comprises a high-pass filter and a delay circuit, said high-pass filter being adapted to absorb relatively low frequency noise and having impedance defining a cut-off frequency for relatively high frequency noise; and

wherein said noise detector varies the detector signal level depending on the noise level inputted thereto, and said radio frequency interference elimination circuit is connected to said noise detector so that it varies the cut-off frequency for holding the radio broadcasting signal level according to the detector signal level.

8. A radio frequency interference elimination device for an automotive radio receiver circuit with automatic gain control, comprising:

a radio receiver circuit including an antenna, a high frequency amplifier, an intermediate frequency amplifier, a signal detector, a voice frequency amplifier and a speaker;

a noise detector for detecting noise created in automotive electric circuits to produce a detector signal upon detecting radio frequency interference noise, said detector being connected to electric power source wiring of the automotive vehicle and adapted to detect said noise flowing through said wiring;

a radio frequency interference elimination circuit interpositioned between said signal detector and said voice frequency amplifier for sequentially sampling detector output and outputting the sampled level thereof, said radio frequency interference elimination circuit being responsive to said detector signal to hold the detector signal and output the held level thereof to said voice frequency amplifier as long as said detector signal is inputted;

wherein said noise detector comprises a high-pass filter and a delay circuit, said high-pass filter being adapted to absorb relatively low frequency noise and having impedance defining a cut-off frequency for relatively high frequency noise; and

wherein said noise detector varies the detector signal level depending on the noise level inputted thereto, and said radio frequency interference elimination circuit is connected to said noise detector so that it varies the cut-off frequency for holding the radio broadcasting signal level according to the detector signal level.

9. A radio frequency interference elimination device in an automotive radio receiver comprising:

a radio circuit for receiving radio broadcasting signal suitable for audio reproduction;

a noise detector for detecting radio frequency interference noise due to automotive electric circuits, said detector being electrically connected to power source wiring to receive radio frequency interference noise therefrom and produce a detector signal when said noise is detected;

a radio frequency interference elimination circuit disposed within said radio circuit and responsive to said detector signal to hold radio broadcasting signal level at an immediate preceeding level for a given period and outputting the held level of radio broadcasting signal for reproduction; and

wherein said noise detector comprises a first delay circuit, a detection device and a second delay circuit connected in sequence, said first delay circuit controls the timing of said second delay circuit so that said noise detector defines a period in which said radio frequency interference elimination circuit holds the radio broadcasting signal level.

10. A radio frequency interference elimination device in an automotive radio receiver with an automatic gain control, comprising:

a radio receiver circuit for receiving a radio broadcasting signal and reproducing an audio sound;

a detector for detecting a radio frequency interference noise in automotive electric circuits and producing a detector signal upon detecting said radio frequency interference noise, said detector being connected to electric power source wiring to pick up noise components therefrom, said detector being adapted to absorb relatively low frequency noise and produce said detector signal in response to relatively high frequency noise;

a radio frequency interference elimination circuit provided within said radio receiver circuit and including a sample/hold means which is normally in sample mode for sequentially sampling radio broadcasting signal inputted thereto and is responsive to said detector signal to hold the signal level of said radio broadcasting signal for a given period, said sample/hold means outputting a signal at the held level while it is maintained at said hold mode; and

wherein said noise detector comprises a first delay circuit, a detection device and a second delay circuit connected in sequence, said first delay circuit controls the timing of said second delay circuit so that said noise detector defines a period in which said radio frequency interference elimination circuit holds the radio broadcasting signal level.

12. The device as set forth in any one of claims 9, 10, or 11, wherein said first and second delay circuits respectively include first and second capacitors having capacitances determined relative to each other, said first capacitor in said first delay circuit defining the charge period and change level of said second capacitor to define the holding period of said radio frequency interference elimination circuit.

11. A radio frequency interference elimination device for an automotive radio receiver circuit with automatic gain control, comprising:

a radio receiver circuit including an antenna, a high frequency amplifier, an intermediate frequency amplifier, a signal detector, a voice frequency amplifier and a speaker;

a noise detector for detecting noise created in automotive electric circuits to produce a detector signal upon detecting radio frequency interference noise, said detector being connected to electric power source wiring of the automotive vehicle and adapted to detect said noise flowing through said wiring;

a radio frequency interference elimination circuit interpositioned between said signal detector and said voice frequency amplifier for sequentially sampling detector output and outputting the sampled lever thereof, said radio frequency interference elimination circuit being responsive to said detector signal to hold the detector signal and output the held level thereof to said voice frequency amplifier as long as said detector signal is inputted; and

wherein said noise detector comprises a first delay circuit, a dection device and a second delay circuit connected in sequence, said first delay circuit controls the timing of said second delay circuit so that said noise detector defines a period in which said radio frequency interference elimination circuit holes the radio braodcasting signal level.

13. A radio frequency interference elimination device in an automotive radio receiver comprising:

a radio circuit for receiving radio broadcasting signal suitable for audio reproduction;

a noise detector for detecting radio frequency interference noise due to automotive electric circuits, said detector being electrically connected to power source wiring to receive radio frequency interference noise therefrom and produce a detector signal when said noise is detected;

a radio frequency interference elimination circuit disposed within said radio circuit and responsive to said detector signal to hold radio broadcasting signal level at an immediate preceeding level for a given period and outputting the held level of radio broadcasting signal for reproduction;

wherein said radio frequency interference elimination circuit comprises a field-effect transistor connected at its base to said noise detector, and a capacitor charged with said radio broadcasting signal inputted thereto, said field-effect transistor being responsive to said detector signal to be turned off and said capacitor being adapted to discharge while said field-effect transistor is turned off; and

wherein said noise detector comprises a diode, a delay circuit, a Zener diode and a transistor connected in sequence, said delay circuit and said Zener diode being connected to produce a constant-duration pulse signal in response to said radio frequency interference noise to turn said transistor on for said constant duration.

16. The device as set forth in any one of claims 13, 14 or 15, wherein said transistor is connected to said radio frequency interference elimination circuit for holding the radio broadcasting signal level.

17. The device as set forth in claim 16, wherein said Zener diode is connected to the cathode terminal of said diode.

14. A radio frequency interference elimination device in an automotive radio receiver with an automatic gain control, comprising:

a radio receiver circuit for receiving a radio broadcasting signal and reproducing an audio sound;

a detector for detecting a radio frequency interference noise in automotive electric circuits and producing a detector signal upon detecting said radio frequency interference noise, said detector being connected to electric power source wiring to pick up noise components therefrom, said detector being adapted to absorb relatively low frequency noise and produce said detector signal in response to relatively high frequency noise;

a radio frequency interference elimination circuit provided within said radio receiver circuit and including a sample/hold means which is normally in sample mode for sequentially sampling radio broadcasting signal inputted thereto and is responsive to said detector signal to hold the signal level of said radio broadcasting signal for a given period, said sample/hold means outputting a signal at the held level while it is maintained at said hold mode;

wherein said radio frequency interference elimination circuit comprises a field-effect transistor connected at its base to said noise detector, and a capacitor charged with said radio broadcasting signal inputted thereto, said field-effect transistor being responsive to said detector signal to be turned off and said capacitor being adapted to discharge while said field-effect transistor is turned off; and

wherein said noise detector comprises a diode, a delay circuit, a Zener diode and a transistor connected in sequence, said delay circuit and said Zener diode being connected to produce a constant-duration pulse signal in response to said radio frequency interference noise to turn said transistor on for said constant duration.

15. A radio frequency interference elimination device for an automotive radio receiver circuit with automatic gain control, comprising:

a radio receiver circuit including an antenna, a high frequency amplifier, an intermediate frequency amplifier, a signal detector, a voice frequency amplifier and a speaker;

a noise detector for detecting noise created in automotive electric circuits to produce a detector signal upon detecting radio frequency interference noise, said detector being connected to electric power source wiring of the automotive vehicle and adapted to detect said noise flowing through said wiring;

a radio frequency interference elimination circuit interpositioned between said signal detector and said voice frequency amplifier for sequentially sampling detector output and outputting the sampled level thereof, said radio frequency interference elimination circuit being responsive to said detector signal to hold the detector signal and output the held level thereof to said voice frequency amplifier as long as said detector signal is inputted;

wherein said radio frequency interference elimination circuit comprises a field-effect transistor connected at its base to said noise detector, and a capacitor charged with said radio broadcasting signal inputted thereto, said field-effect transistor being responsive to said detector signal to be turned off and said capacitor being adapted to discharge while said field-effect transistor is turned off; and

wherein said noise detector comprises a diode, a delay circuit, a Zener diode and a transistor connected in sequence, said delay circuit and said Zener diode being connected to produce a constant-duration pulse signal in response to said radio frequency interference noise to turn said transistor on for said constant duration.

18. A radio frequency interference elimination device in an automotive radio receive comprising:

a radio circuit for receiving radio broadcasting signal suitable for audio reproduction;

a noise detector for detecting radio frequency interference noise due to automotive electric circuits, said detector being electrically connected to power source wiring to receive radio frequency interference noise therefrom and produce a detector signal when said noise is detected;

a radio frequency interference elimination circuit disposed within said radio circuit and responsive to said detector signal to hold broadcasting signal level at an immediate preceeding level for a given period and outputting the held level of radio broadcasting signal for reproduction;

a radio frequency interference elimination circuit provided within said radio receiver circuit and including a sample/hold means which is normally in sample mode for sequentially sampling radio broadcasting signal inputted thereto and is responsive to said detector signal to hold the signal level of said radio braodcasting signal for a given period, said sample/hold means outputting a signal at the held level while it is maintained at said hold mode;

wherein said radio frequency interference elimination circuit comprises a field-effect transistor connected at its base to said noise detector, and a capacitor charged with said radio broadcasting signal inputted thereto, said field-effect transistor being responsive to said detector signal to be turned off and said capacitor being adapted to discharge while said field-effect transistor is turned off; and

wherein said noise detector varies the detector signal level depending on the noise level inputted thereto, and said radio frequency interference elimination circuit is connected to said noise detector to vary a cut-off frequency for holding the radio broadcasting signal level according to the detector signal level.

19. A radio frequency interference elimination device in an automotive radio receiver with an automatic gain control, comprising:

a radio receiver circuit for receiving a radio broadcasting signal and reproducing an audio sound;

a detector for detecting a radio frequency interference noise in automotive electric circuits and producing a detector signal upon detectng said radio frequency interference noise, said detector being connected to electric power source wiring to pick up noise components therefrom, said detector being adapted to absorb relatively low frequency noise and produce said detector signal in response to relatively high frequency noise;

a radio frequency interference elimination circuit provided within said radio receiver circuit and including a sample/hold means which is normally in sample mode for sequentially sampling radio broadcasting signal inputted thereto and is responsive to said detector signal to hold the signal level of said radio broadcasting signal for a given period, said sample/hold means outputting a signal at the held level while it is maintained at said hold mode;

wherein said radio frequency interference elimination circuit comprises a field-effect transistor connected at its base to said noise detector, and a capacitor charged with said radio broadcasting signal inputted thereto, said field-effect transistor being responsive to said detector signal to be turned off and said capacitor being adapted to discharge while said field-effect transistor is turned off; and

wherein said noise detector varies the detector signal level depending on the noise level inputted thereto, and said radio frequency interference elimination circuit is connected to said noise detector to vary a cut-off frequency for holding the radio broadcasting signal level according to the detector signal level.

20. A radio frequency interference elimination device for an automotive radio receiver circuit with automatic gain control, comprising:

a radio receiver circuit including an antenna, a high frequency amplifier, an intermediate frequency signal amplifier, a signal detector, a voice frequency amplifier and a speaker;

a noise detector for detecting noise created in automotive electric circuits to produce a detector signal upon detecting radio frequency interference noise, said detector being connected to electric power source wiring of the automotive vehicle and adapted to detect said noise flowing through said wiring;

a radio frequency interference elimination circuit interpositioned between said signal detector and said voice frequency amplifier for sequentially sampling detector output and outputting the sampled level thereof, said radio frequency interference elimination circuit being responsive to said detector signal to hold the detector to, signal and output the held level thereof to said voice it frequency amplifier as long as said detector signal is inputted; and

holding the radio broadcasting signal level according to the detector signal level;

wherein said radio frequency interference elimination circuit comprises a field-effect transistor connected at its base to said noise detector, and a capacitor charged with said radio broadcasting signal inputted thereto, said field-effect transistor being responsive to said detector signal to be turned off and said capacitor being adapted to discharge while said field-effect transistor is turned off; and

wherein said noise detector varies the detector signal level depending on the noise level inputted thereto, and said radio frequency interference elimination circuit is connected to said noise detector to vary a cut-off frequency for holding the radio broadcasting signal level according to the detector signal level.

21. A radio frequency interference elimination device in an automotive radio receiver comprising:

a radio circuit for receiving radio broadcasting signal suitable for audio reproduction;

a noise detector for detecting radio frequency interference noise due to automotive electric circuits, said detector being electrically connected to power source wiring to receive radio frequency interference noise therefrom and produce a detector signal when said noise is detected;

a radio frequency interference elimination circuit disposed within said radio circuit and responsive to said detector signal to hold radio broadcasting signal level at an immediate preceeding level for a given period and outputting the held level of radio broadcasting signal for reproduction;

wherein said radio frequency interference elimination circuit comprises a field-effect transistor connected at its base to said noise detector, and a capacitor charged with said radio broadcasting signal inputted thereto, said field-effect transistor being responsive to said detector signal to be turned off and said capacitor being adapted to discharge while said field-effect transistor is turned off; and

wherein said noise detector comprises a first delay circuit, a detection device and a second delay circiut connected in sequence, said first delay circuit controlling the timing of said second delay circuit so that said noise detector defines a period in which said radio frequency interference elimination circuit holds the radio broadcasting signal level.

24. The device as set forth in any one of claims 21, 22 or 23, wherein said first and second delay circuits respectively include first and second capacitors having capacitance determined relative to each other, said first capacitor in said first delay circuit defining the charge period and charge level of said second capacitor to define the holding period of said radio frequency interference elimination circuit.

22. A radio frequency interference elimination device in an automotive radio receiver with an automatic gain control, comprising:

a radio receiver circuit for receiving a radio broadcasting signal and reproducing an audio sound;

a detector for detecting a radio frequency interference noise in automotive electric circuits and producing a detector signal upon detecting said radio frequency interference noise, said detector being connected to electric power source wiring to pick up noise components therefrom, said detector being adapted to absorb relatively low frequency noise and produce said detector signal in response to relatively high frequency noise;

a radio frequency interference elimination circuit provided within said radio receiver circuit and including a sample/hold means which is normally in sample mode for sequentially sampling radio broadcasting signal inputted thereto and is responsive to said detector signal to hold the signal level of said radio broadcasting signal for a given period, said sample/hold means outputting a signal at the held level while it is maintained at said hold mode;

wherein said radio frequency interference elimination circuit comprises a field-effect transistor connected at its base to said noise detector, and a capacitor charged with said radio broadcasting signal inputted thereto, said field-effect transistor being responsive to said detector signal to be turned off and said capacitor being adapted to discharge while said field-effect transistor is turned off; and

wherein said noise detector comprises a first delay circuit, a detection device and a second delay circuit connected in sequence, said first delay circuit controlling the timing of said second delay circuit so that said noise detector defines a period in which said radio frequency interference elimination circuit holds the radio broadcasting signal level.

23. A radio frequency interference elimination device for an automotive radio receiver circuit with automatic gain control, comprising:

a radio receiver circuit including an antenna, a high frequency amplifier, an intermediate frequency amplifier, a signal detector, a voice frequency amplifier and a speaker;

a noise detector for detecting noise created in automotive electric circuits to produce a detector signal upon detecting radio frequency interference noise, said detector being connected to electric power source wiring of the automotive vehicle and adapted to detect said noise flowing through said wiring;

a radio frequency interference elimination circuit interpositioned between said signal detector and said voice frequency amplifier for sequentially sampling detector output and outputting the sampled level thereof, said radio frequency interference elimination circuit being responsive to said detector signal to hold the detector signal and output the held level thereof to said voice frequency amplifier as long as said detector signal is inputted;

wherein said radio frequency interference elimination circuit comprises a field-effect transistor connected at its base to said noise detector, and a capacitor charged with said radio broadcasting signal inputted thereto, said field-effect transistor being responsive to said detector signal to be turned off and said capacitor being adapted to discharge while said field-effect transistor is turned off; and

wherein said noise detector comprises a first delay circuit, a detection device and a second delay circuit connected in sequence, said first delay circuit controlling the timing of said second delay circuit so that said noise detector defines a period in which said radio frequency interference elimination circuit holds the radio broadcasting signal level.