Claims
- 1. In a receiver for receiving either an analog information signal or a digital information signal modulated on a carrier signal at a carrier frequency subsequent to transmission thereof by a transmitter, wherein the receiver includes a frequency translator for translating the carrier frequency to an intermediate frequency and maintaining the intermediate frequency at a desired value responsive to a reference frequency, an apparatus for automatically controlling the reference frequency when the receiver receives either the analog information signal or the digital information signal, comprising:
- a phase detector coupled to receive the reference frequency and the intermediate frequency and operative to detect a first measure of frequency error between the reference frequency and the intermediate frequency;
- a processor coupled to receive the reference frequency and the intermediate frequency and operative to determine a second measure of frequency error between the reference frequency and the intermediate frequency;
- a current device coupled to receive the first measure of frequency error when the receiver receives the analog information signal and coupled to receive the second measure of frequency error when receiver receives the digital information signal, and operative to produce a current signal responsive to either the first or the second measure of frequency error; and
- a capacitive device coupled to receive the current signal and operative to produce a frequency control signal responsive to the current signal to automatically control thereby the reference frequency when the receiver receives either the analog information signal or the digital information signal.
- 2. An apparatus according to claim 1 further comprising a switch, operatively coupled to the current device, coupled to receive the first measure of frequency error and the second measure of frequency error and operable to alternatively select the first measure of frequency error when the receiver receives the analog information signal and the second measure of frequency error when receiver receives the digital information signal.
- 3. An apparatus according to claim 2 wherein the switch is actuated responsive to either the analog information signal or the digital information signal.
- 4. An apparatus according to claim 2 wherein the switch comprises a multiplexer.
- 5. An apparatus according to claim 1 wherein the first measure of frequency error and the second measure of frequency error each comprises a first signal for adjusting the reference frequency up in frequency and a second signal for adjusting the reference frequency down in frequency.
- 6. An apparatus according to claim 1 wherein the frequency control signal responds to the current signal at a first rate in time when the receiver receives the analog information signal and at a second rate in time when the receiver receives the digital information signal.
- 7. In a receiver for receiving either an analog information signal or a digital information signal modulated on a carrier signal at a carrier frequency subsequent to transmission thereof by a transmitter, wherein the receiver includes a frequency translator for translating the carrier frequency to an intermediate frequency and maintaining the intermediate frequency at a desired value responsive to a reference frequency, a method for automatically controlling the reference frequency when the receiver receives either the analog information signal or the digital information signal, comprising the steps of:
- detecting a first measure of frequency error between the reference frequency and the intermediate frequency when the receiver receives the analog information signal;
- determining a second measure of frequency error between the reference frequency and the intermediate frequency when receiver receives the digital information signal;
- producing a current signal, wherein the current signal is responsive to the first measure of frequency error when the receiver receives the analog information signal, and wherein the current signal is further responsive to the second measure of frequency error when receiver receives the digital information signal; and
- producing a frequency control signal responsive to the current signal to automatically control thereby the reference frequency when the receiver receives either the analog information signal or the digital information signal.
- 8. A method according to claim 7 further comprising the step of alternatively selecting the first measure of frequency error when the receiver receives the analog information signal and the second measure of frequency error when receiver receives the digital information signal.
- 9. A method according to claim 8 wherein the step of alternatively selecting is determined responsive to either the analog information signal or the digital information signal.
- 10. A method according to claim 8 wherein the step of alternatively selecting further comprises the step of multiplexing the first measure of frequency error when the receiver receives the analog information signal and the second measure of frequency error when receiver receives the digital information signal.
- 11. A method according to claim 7 wherein the first measure of frequency error and the second measure of frequency error each comprises a first signal for adjusting the reference frequency up in frequency and a second signal for adjusting the reference frequency down in frequency.
- 12. A method according to claim 7 wherein the frequency control signal responds to the current signal at a first rate in time when the receiver receives the analog information signal and at a second rate in time when the receiver receives the digital information signal.
- 13. A communication unit comprising:
- a receiver for receiving either an analog information signal or a digital information signal modulated on a carrier signal at a carrier frequency subsequent to transmission thereof by a transmitter, the receiver including:
- a frequency translator for translating the carrier frequency to an intermediate frequency and maintaining the intermediate frequency at a desired value responsive to a reference frequency;
- a phase detector coupled to receive the reference frequency and the intermediate frequency and operative to detect a first measure of frequency error between the reference frequency and the intermediate frequency;
- a processor coupled to receive the reference frequency and the intermediate frequency and operative to determine a second measure of frequency error between the reference frequency and the intermediate frequency;
- a current device coupled to receive the first measure of frequency error when the receiver receives the analog information signal and coupled to receive the second measure of frequency error when receiver receives the digital information signal, and operative to produce a current signal responsive to either the first or the second measure of frequency error; and
- a capacitive device coupled to receive the current signal and operative to produce a frequency control signal responsive to the current signal to automatically control thereby the reference frequency when the receiver receives either the analog information signal or the digital information signal.
- 14. A method of operating a communication unit comprising the step of:
- receiving either an analog information signal or a digital information signal modulated on a carrier signal at a carrier frequency subsequent to transmission thereof by a transmitter, the step of receiving further including the steps of:
- translating the carrier frequency to an intermediate frequency and maintaining the intermediate frequency at a desired value responsive to a reference frequency;
- detecting a first measure of frequency error between the reference frequency and the intermediate frequency when the receiver receives the analog information signal;
- determining a second measure of frequency error between the reference frequency and the intermediate frequency when receiver receives the digital information signal;
- producing a current signal, wherein the current signal is responsive to the first measure of frequency error when the receiver receives the analog information signal, and wherein the current signal is further responsive to the second measure of frequency error when receiver receives the digital information signal; and
- producing a frequency control signal responsive to the current signal to automatically control thereby the reference frequency when the receiver receives either the analog information signal or the digital information signal.
Parent Case Info
This is a continuation of application Ser. No. 08/103,004, filed Aug. 6, 1993 and now abandoned.
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Number |
Name |
Date |
Kind |
4817192 |
Phillips et al. |
Mar 1989 |
|
4955074 |
Omoto |
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5163159 |
Rich et al. |
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Continuations (1)
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Number |
Date |
Country |
Parent |
103004 |
Aug 1993 |
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