Paging receiver with continuously tunable antenna and RF amplifier

• US 5,077,834 A
• Filed: 07/18/1989
• Issued: 12/31/1991
• Est. Priority Date: 03/28/1989
• Status: Expired due to Term

• Current Assignee: Flatt Morris Associates SA, Management And Investment, S.A.
• Original Assignee: Telefind Corporation
• Inventors: Campana, Thomas J. Jr., Andros, Andrew A.
• Primary Examiner(s): Eisenzopf, Reinhard J.
• Assistant Examiner(s): Urban, Edward
• Application Number:
  US07/381,483
• Time in Patent Office: 896 Days
• Field of Search: 455/193, 455/195, 455/200, 455/266, 455/289, 455/38, 455/228, 455/341, 455/184, 455/234, 455/226, 340/825.44
• US Class Current: 455/193.1
• CPC Class Codes: H03J 7/08 using varactors, i.e. voltage variable reactive diodes H03J7/06 takes precedence
• CPC Class Codes: H04B 1/18 Input circuits, e.g. for coupling to an antenna or a transmission line coupling networks between antennas or lines and receivers independent of the nature of the receiver H03H
• CPC Class Codes: H04W 88/022 Selective call receivers

Abstract

A RF paging receiver which is tunable to channels to receive pages comprising characters to be displayed with the pages being transmitted in a plurality of licensed frequency bands with each band containing a plurality of FM channels in which signal strength of pages on received channels in the bands varies as a result of variable antenna gain with programming of channels being accomplished by channel programming commands in accordance with the invention includes a tunable antenna (12, 14) having a reception bandwidth spanning the frequency bands with the antenna being tunable in response to an antenna tuning signal to achieve maximum antenna gain for a received channel in any one of the plurality of licensed frequency bands; a RF tuner (16), coupled to the tunable antenna, for receiving individual channels from the bands in response to varying a receiver tuning signal specifying reception of one of the channels within the plurality of frequency bands, the RF tuner comprising a plurality of RF amplifiers (102, 104 and 106) with each RF amplifier for amplifying channels from at least one different licensed frequency band, each RF amplifier having an operating bandwidth which is narrower in frequency than the frequency band of channels applied to the RF amplifier and which is shiftable to center the operating bandwidth within the frequency band of channels amplified by the RF amplifier on the specified channel; an IF signal processor (34), coupled to the RF tuner, for producing an intermediate frequency signal, for producing the antenna tuning signal which is a function of the level of the intermediate signal during operation of the RF tuner to dynamically tune the antenna to achieve maximum antenna gain in response to variation in the gain of the antenna in receiving a channel from any one of the channels within the frequency bands and for providing the RF amplifier tuning signal which is a function of the level of the intermediate frequency signal and the receiver tuning signal; a display (64'"'"') for displaying characters contained within a page; and a controller (24), coupled to the intermediate frequency signal, and responsive to channel programming commands, for decoding a change in at least one channel contained within a channel programming command and controlling generation of the receiver tuning signal applied to the RF tuner specifying reception of one channel specified by a received channel programming command from one of the frequency bands to cause reception of the specified channel and display of characters in pages received on the channel on the display.

Claims

1. A RF paging receiver which is tunable to at least one specified channel comprising:

a RF tuner, for receiving the specified channel in response to a channel tuning signal specifying reception of the specified channel;

an intermediate frequency circuit coupled to the RF tuner for producing an intermediate frequency signal and a received signal strength indicator which is proportional to a level of the intermediate frequency signal;

a controller, coupled to the intermediate frequency signal, controlling generation of the channel tuning signal to cause the RF tuner to be tuned to receive the specified channel and controlling generation of an amplifier tuning signal; and

wherein

the RF tuner comprises a tunable RF amplifier, responsive to the received signal strength indicator and a stored amplifier tuning signal which is a function of the channel being received, which maximized gain of the RF amplifier by shifting a center of an operating bandwidth of the RF amplifier in response to changing the amplifier tuning signal with the RF amplifier center operating bandwidth being shifted from a center operating bandwidth produced by the stored amplifier tuning signal by a change in magnitude of the amplifier tuning signal from the stored amplifier tuning signal until the received signal strength indicator reaches a maximum magnitude indicating maximum RF amplifier gain.

2. A RF receiver which is tunable to a plurality of channels within at least one frequency band comprising:

a RF tuner, for receiving a channel in response to a channel tuning signal specifying reception of the received channel and including a tunable RF amplifier having an operating bandwidth which is narrower in frequency than the at least one frequency band and which is shiftable to center a center of the operating bandwidth on the specified channel in response to varying an RF amplifier tuning signal to maximize gain of the RF amplifier;

an RF amplifier tuning signal generating circuit, responsive to a received signal strength indicator produced by an intermediate frequency circuit coupled to the RF amplifier during receiving the received channel and a stored amplifier tuning signal, for varying the RF amplifier tuning signal from the stored amplifier tuning signal to shift the center of the operating bandwidth from a center of the operating bandwidth produced by the stored amplifier tuning signal to another center of operating bandwidth which increases the received signal strength indicator to a maximum signal level resulting in maximum gain of the RF amplifier; and

a controller for controlling the generation of the applied channel tuning signal.

3. A RF receiver in accordance with claim 2 wherein:

the stored RF amplifier tuning signal is initially applied to the RF amplifier to cause the RF amplifier to have a gain which is chosen to not produce the maximum gain for the channel specified by the channel tuning signal and thereafter the RF amplifier tuning signal applied to the RF amplifier is changed from the stored RF amplifier tuning signal by the RF amplifier tuning signal generating circuit which shifts the center of the operating bandwidth of the RF amplifier to cause the received signal strength indicator to produce a maximum signal level resulting in maximum gain being produced by the RF amplifier for the channel specified by the channel tuning signal.

4. A RF receiver in accordance with claim 3 wherein:

the RF amplifier tuning signal generating circuit incrementally changes the amplifier tuning signal from the stored amplifier tuning signal until the signal level of the received signal strength indicator produced by the intermediate frequency circuit reaches a maximum level and in response to the received signal strength indicator reaching a maximum level sets the RF amplifier tuning signal to the RF amplifier tuning signal which produced the maximum level of the received signal strength indicator by the intermediate frequency signal circuit for receiving the channel specified by the channel tuning signal to cause the RF amplifier to produce maximum gain.

5. A RF receiver in accordance with claim 4 wherein:

the RF amplifier tuning signal generating circuit in producing the amplifier tuning signal which produces maximum gain executes a recurring process of incremental changing the RF amplifier tuning signal, storing a resultant signal level of the received signal strength indicator produced by the intermediate frequency circuit, compares the resultant signal level of the received signal strength indicator with a signal level of the received signal strength indicator produced by the intermediate frequency circuit produced prior to the incrementally changing the RF amplifier tuning signal to determine if the incremental change in RF amplifier tuning signal caused the resultant signal level of the received signal strength indicator from the intermediate frequency circuit to increase, and repeats incrementally changing of RF amplifier tuning signal, storing the resultant signal level of the received signal strength indicator and comparing the resultant and previous signal levels of the received signal strength indicator produced by the intermediate frequency circuit until the signal level of the received signal strength indicator produced by the intermediate frequency circuit reaches a maximum signal level.

6. A RF receiver in accordance with claim 5 wherein:

a phase locked loop coupled to the applied channel tuning signal;

a voltage controlled oscillator, coupled to the phase locked loop, for outputting a frequency specified by the applied channel tuning signal to a mixer within the RF tuner; and

the phase locked loop is locked to the specified channel during tuning of the RF amplifier and during reception on the specified channel.

7. A RF receiver in accordance with claim 6 wherein:

the RF amplifier tuning circuit stores a plurality of RF amplifier tuning signals and applies a single stored RF amplifier tuning signal to the tunable RF amplifier which is a function of the channel specified by the channel tuning signal.

8. A RF receiver in accordance with claim 7 wherein:

the channels to which the receiver is tunable are contained in a plurality of frequency bands with each band containing a plurality of channels to which the receiver is tunable with a plurality of RF amplifier tuning signals being stored for each band.

9. A RF receiver in accordance with claim 5 wherein:

the RF amplifier tuning circuit stores a plurality of RF amplifier tuning signals and applies a single stored RF amplifier tuning signal to the tunable RF amplifier which is a function of the channel specified by the channel tuning signal.

10. A RF receiver in accordance with claim 9 wherein:

the channels to which the receiver is tunable are contained in a plurality of frequency bands with each band containing a plurality of channels to which the receiver is tunable with a plurality of RF amplifier tuning signals being stored for each band.

11. A RF receiver in accordance with claim 4 wherein the RF tuner further comprises:

a phase locked loop coupled to the applied channel tuning signal;

a voltage controlled oscillator, coupled to the phase locked loop, for outputting a frequency specified by the applied channel tuning signal to a mixer within the RF tuner; and

the phase locked loop is locked to the specified channel during tuning of the RF amplifier an during reception on the specified channel.

12. A RF receiver in accordance with claim 11 wherein:

the RF amplifier tuning circuit stores a plurality of RF amplifier tuning signals and applies a single stored RF amplifier tuning signal to the tunable RF amplifier which is a function of the channel specified by the channel tuning signal.

13. A RF receiver in accordance with claim 12 wherein:

the channels to which the receiver is tunable are contained in a plurality of frequency bands with each band containing a plurality of channels to which the receiver is tunable with a plurality of RF amplifier tuning signals being stored for each band.

14. A RF receiver in accordance with claim 4 wherein:

the RF amplifier tuning circuit stores a plurality of RF amplifier tuning signals and applies a single stored RF amplifier tuning signal to the tunable RF amplifier which is a function of the channel specified by the channel tuning signal.

15. A RF receiver in accordance with claim 14 wherein:

the channels to which the receiver is tunable are contained in a plurality of frequency bands with each band containing a plurality of channels to which the receiver is tunable with a plurality of RF amplifier tuning signals being stored for each band.

16. A RF receiver in accordance with claim 3 wherein:

the RF amplifier tuning circuit stores a plurality of RF amplifier tuning signals and applies a single stored RF amplifier tuning signal to the tunable RF amplifier which is a function of the channel specified by the channel tuning signal.

17. A RF receiver in accordance with claim 16 wherein:

the channels to which the receiver is tunable are contained in a plurality of frequency bands with each band containing a plurality of channels to which the receiver is tunable with a plurality of RF amplifier tuning signals being stored for each band.

18. A RF receiver in accordance with claim 3 wherein the RF tuner further comprises:

a phase locked loop coupled to the applied channel tuning signal;

a voltage controlled oscillator, coupled to the phase locked loop, for outputting a frequency specified by the applied channel tuning signal to a mixer within the RF tuner; and

the phase locked loop is locked to the specified channel during tuning of the RF amplifier and during reception on the specified channel.

19. A RF receiver in accordance with claim 18 wherein:

the RF amplifier tuning circuit stores a plurality of RF amplifier tuning signals and applies a single stored RF amplifier tuning signal to the tunable RF amplifier which is a function of the channel specified by the channel tuning signal.

20. A RF receiver in accordance with claim 19 wherein:

the channels to which the receiver is tunable are contained in a plurality of frequency bands with each band containing a plurality of channels to which the receiver is tunable with a plurality of RF amplifier tuning signals being stored for each band.

21. A RF receiver in accordance with claim 2 wherein the RF tuner further comprises:

a phase locked loop coupled to the applied channel tuning signal;

a voltage controlled oscillator, coupled to the phase locked loop, for outputting a frequency specified by the applied channel tuning signal to a mixer within the RF tuner; and

the phase locked loop is locked to the specified channel during tuning of the RF amplifier an during reception on the specified channel.

22. A RF receiver in accordance with claim 21 wherein:

the RF amplifier tuning circuit stores a plurality of RF amplifier tuning signals and applies a single stored RF amplifier tuning signal to the tunable RF amplifier which is a function of the channel specified by the channel tuning signal.

23. A RF receiver in accordance with claim 22 wherein:

the channels to which the receiver is tunable are contained in a plurality of frequency bands with each band containing a plurality of channels to which the receiver is tunable with a plurality of RF amplifier tuning signals being stored for each band.

24. A RF receiver in accordance with claim 2 wherein:

the RF amplifier tuning circuit stores a plurality of RF amplifier tuning signals and applies a single stored RF amplifier tuning signal to the tunable RF amplifier which is a function of the channel specified by the channel tuning signal.

25. A RF receiver in accordance with claim 24 wherein:

the channels to which the receiver is tunable are contained in a plurality of frequency bands with each band containing a plurality of channels to which the receiver is tunable with a plurality of RF amplifier tuning signals being stored for each band.

26. A RF receiver, which is tunable to a plurality channels in at least one frequency band, having a received signal strength which varies during the reception of a received channel within the at least one frequency band comprising:

a tunable antenna which is continuously tunable in response to an antenna tuning signal to vary antenna gain for a received channel during reception of a transmission on the received channel to produce a maximum antenna gain;

a RF tuner, coupled to the tunable antenna, for receiving the channel in response to a channel tuning signal specifying reception of the received channel;

an intermediate frequency circuit, coupled to the RF tuner, for producing an intermediate frequency signal and a received signal strength indicator which is proportional to a level of the signal on the received channel;

an antenna tuning circuit, responsive to the received signal strength indicator and to a stored antenna tuning signal which is a function of the channel being received, for continuously generating the antenna tuning signal which produces the maximum antenna gain for the received channel, the antenna tuning circuit comparing at least one current received signal strength indicator with at least one stored previous received signal strength indicator to determine if the at least one received current signal strength indicator is less than the at least one previous stored received signal strength indicator by an amount greater than a first threshold and if the difference is greater than the threshold the antenna tuning circuit changes the antenna tuning signal to cause an increase in the received signal strength indicator from the at least one current received signal strength indicator to a maximum signal level indicating the maximum antenna gain; and

a controller controlling generation of the channel tuning signal to cause the RF tuner to be tuned to receiver the received channel.

27. A RF receiver in accordance with claim 26 wherein:

the at least one current received signal strength indicator is an average of a plurality of samples of the received signal strength indicator taken in time from a previously taken sample up to a current sample; and

the at least one previous signal strength indicator is an average of a plurality of samples of the received signal strength indicator taken in time up to the previously taken sample which is included in the average of the plurality of samples within the average of the plurality of samples of current received signal strength indicator.

28. A RF receiver in accordance with claim 27 wherein:

the samples within the averages are taken as sequential samples.

29. A RF receiver in accordance with claim 28 wherein:

the change in the antenna tuning signal is produced by incrementally changing the antenna tuning signal produced by the antenna tuning circuit to cause the signal strength indicator to increase.

30. A RF receiver in accordance with claim 29 wherein:

the antenna tuning circuit incrementally changes the signal strength indicator by incrementally increasing or incrementally decreasing the antenna signal until the signal strength increases from the at least one current stored signal strength indicator.

31. A RF receiver in accordance with claim 30 wherein:

the incrementally increasing or decreasing of the antenna tuning signal is comprised of changes of the antenna tuning signal by a smaller increment if the change in signal strength indicator determined by the comparison of the stored signal strength indicators is less than a second threshold and by a larger increment if the change in signal strength indicator determined by the comparison of the stored signal strength indicators is greater than the second threshold.

32. A RF receiver in accordance with claim 26 wherein:

the change in the antenna tuning signal is produced by incrementally changing the antenna tuning signal produced by the antenna tuning circuit to cause the signal strength indicator to increase.

33. A RF receiver in accordance with claim 32 wherein:

the antenna tuning circuit incrementally changes the signal strength indicator by incrementally increasing or incrementally decreasing the antenna signal until the signal strength increases from the at least one current stored signal strength indicator.

34. A RF receiver in accordance with claim 33 wherein:

the incrementally increasing or decreasing of the antenna tuning signal is comprised of changes of the antenna tuning signal by a smaller increment if the change in signal strength indicator determined by the comparison of the stored signal strength indicators is less than a second threshold and by a larger increment if the change in signal strength indicator determined by the comparison of the stored signal strength indicators is greater than the second threshold.

35. A RF receiver in accordance with claim 27 wherein:

the change in the antenna tuning signal is produced by incrementally changing the antenna tuning signal produced by the antenna tuning circuit to cause the signal strength indicator to increase.

36. A RF receiver in accordance with claim 35 wherein:

the antenna tuning circuit incrementally changes the signal strength indicator by incrementally increasing or incrementally decreasing the antenna signal until the signal strength increases from the at least one current stored signal strength indicator.

37. A RF receiver in accordance with claim 36 wherein:

the incrementally increasing or decreasing of the antenna tuning signal is comprised of changes of the antenna tuning signal by a smaller increment if the change in signal strength indicator determined by the comparison of the stored signal strength indicators is less than a second threshold and by a larger increment if the change in signal strength indicator determined by the comparison of the stored signal strength indicators is greater than the second threshold.

38. A RF receiver, which is tunable to a plurality of channels within at least one frequency band, having a received signal strength which varies during the reception of a received channel within the at least one frequency band comprising:

a tunable antenna which is continuously tunable in response to an antenna tuning signal to vary antenna gain for a received channel during reception of a transmission on the received channel to produce maximum antenna gain;

a RF tuner, coupled to the tunable antenna, for receiving a channel in response to a channel tuning signal specifying reception of the received channel and including a tunable RF amplifier having an operating bandwidth which is narrower in frequency than the at least one frequency band and which is shiftable to center a center of the operating bandwidth on the specified channel in response to varying an RF amplifier tuning signal to maximize gain of the RF amplifier;

an RF amplifier tuning signal generating circuit, responsive to a received signal strength indicator produced by an intermediate frequency circuit coupled to the RF amplifier during receiving the received channel and a stored amplifier tuning signal, for varying the RF amplifier tuning signal from the stored amplifier tuning signal to shift the center of the operating bandwidth from a center of the operating bandwidth produced by the stored amplifier tuning signal to another center of operating bandwidth to maximize signal level resulting in maximize gain of the RF amplifier;

an antenna tuning circuit, responsive to the received signal strength indicator and to a stored antenna tuning signal which is a function of the channel being received, for continuously generating the antenna tuning signal which produces the maximum antenna gain for the received channel, the antenna tuning circuit comparing at least one current received signal strength indicator with at least one previous stored received signal strength indicator to determine if the at least one received current signal strength indicator is less than the at least one previous stored received signal strength indicator by an amount greater than a threshold and if the difference is greater than the threshold the antenna tuning circuit changes the antenna tuning signal to increase the signal strength indicator from the at least one current signal strength indicator to a maximum signal level to produce the maximum antenna gain; and

a controller controlling generating of the channel tuning signal to cause the RF tuner to be tuned to receive the received channel.