Sectored antenna receiving system

• US 4,317,229 A
• Filed: 02/25/1980
• Issued: 02/23/1982
• Est. Priority Date: 05/02/1977
• Status: Expired due to Term

• Current Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Craig, Timothy P., Stimple, James R., Erickson, Paul M.
• Primary Examiner(s): Bookbinder, Marc E.
• Application Number:
  US06/124,484
• Time in Patent Office: 729 Days
• Field of Search: 455/272, 455/277, 455/133-136, 455/140
• US Class Current: 455/277.1
• CPC Class Codes: H04B 7/0808 comparing all antennas before reception
• CPC Class Codes: H04W 16/24 Cell structures

Abstract

A plurality of horizontally directive antenna sectors are arranged in a configuration to receive signals from remote transmitters over a given angle in the horizontal plane. A scanning system is operative in one of several modes to sequentially couple each sector to a receiver. In its first mode, each sector is sequentially scanned with the peak signal level therefrom being compared to a reference level. If the signal level on any sector exceeds the reference level the scanner activates to its second mode wherein scanning of all sectors continues for a predetermined interval after which the system advances to a selective scanning mode wherein scan is limited to that sector with the largest stored signal level relative to the reference level, and to those sectors adjacent said sector for a predetermined time interval. At the end of this interval, scanning is inhibited and the receiver is coupled to that sector which exhibited the strongest relative signal level during the scanning sequences. In this listen mode, if the signal level from the sector falls to a minimum level or a coded squelch is undetected for a given period, the system reverts to the first scanning mode.

The system periodically updates the reference levels to account for changes in background noise or the presence of an interfering signal.

Claims

1. A radio frequency communication system, comprising:

(a) sectored antenna array means having a plurality of antenna sectors;

(b) receiver means adapted for receiving radio frequency signals from the sectored antenna array including signal strength detector means for producing a peak signal strength value representative of the strength of the radio frequency signal being received;

(c) means for sequentially coupling the individual antenna sectors to said receiver means thereby scanning the antenna array means, and having scan control means for controlling scanning, including

storing means for storing peak signal strength values from the receiver during scanning,

comparator means for comparing said peak signal strength values to a reference level and generating a control signal in response to a predetermined relationship therebetween,

scan means for general scanning of the antenna array means and storing of the peak signal strength value from each sector in said storing means, for terminating the scanning after a first time interval in response to the control signal, and then scanning only a number of selected sectors less than said plurality for a second time interval, and for inhibiting the scanning and coupling the receiver to a selected one of the selected sectors.

2. The communication system of claim 1 wherein the scan means reverts from inhibiting the scanning to general scanning in response to the signal level from the sector to which the receiver is coupled falling to a predetermined level for a predetermined time period.

3. The communication system of claim 1 further comprising means to squelch output from the receiver except when the scan control means is inhibiting the scan.

4. The communication system of claim 1 wherein the storing means further comprises:

a first storage array, having a storage cell corresponding to each sector, for storing the peak signal strength value from each sector during the scanning modes,

a second storage array, having a storage cell corresponding to each sector, for storing therein a reference level corresponding to each sector; and

wherein the comparator means generates the control signal in response to the peak signal level for at least one sector stored in the first array exceeding the reference level for that sector stored in the second array by a predetermined value.

5. The communication system of claim 4 further comprising updating means for periodically transferring stored sector signal strength values for each sector from the first storage array to the second storage array when the scan means is performing the general scan of the antenna array.

6. The communication system of claim 4 wherein the selected sectors include that sector whose first array stored value exceeds its second array stored value by the greatest amount, and those sectors in a predetermined orientation with respect to said sector.

7. The communication system of claim 6 wherein the receiver is coupled to that selectively scanned sector whose first array stored signal level exceeds the second array stored reference level by the greatest amount.

8. The communication system of claim 1 wherein the receiver means comprises means for detecting the presence of a coded signal on the received radio frequency signal.

9. The communication system of claim 8 wherein the scan means continues inhibiting the scanning only if the radio frequency signal from the selected sector contains said coded signal, the scan means otherwise reverting to general scanning.

10. The communication system of claim 5 wherein the receiver means comprises means for detecting the presence of a coded signal on the received radio frequency signal.

11. The communication system of claim 10 wherein the scan means continues inhibiting the scanning only if the radio frequency signal from the selected sector contains said coded signal the scan means otherwise reverting to general scanning.

12. The communication system of claim 11 wherein the updating means further comprises means for transferring the stored sector strength values from the first storage array to the second storage array in response to the scan means reverting to general scanning as a result of the signal from said selected sector initially failing to contain said coded signal.

13. The communication system of claim 11 or 12 wherein the updating means further comprises means for zeroing the first storage array in response to the scan means reverting to general scanning as a result of the loss of said coded signal from said selected sector for a predetermined minimum time.

14. The communication system of claim 5 or 12 wherein the means for transferring performs a nonlinear transfer of stored peak signal strength values from the first storage array to the second storage array.

15. The method of receiving radio frequency signals with a multisectored antenna array and a receiver, comprising the steps of:

(a) scanning the full array by sequentially sampling the radio frequency signal from each sector;

(b) detecting the strength of the sampled signal from each sector;

(c) comparing said signal strengths to a reference level and determining whether the signal strength level of at least one sector exceeds said reference level;

(d) continuing scan of all sectors for a first time interval subsequent to determining that a sector signal strength exceeds said reference level;

(e) scanning only a number of selected sectors of the antenna array which is less than the full array at the conclusion of the first time interval for a second time internal; and

(f) inhibiting scan following said second time interval and coupling the receiver to a selected one of the selected sectors.

16. The method of claim 15 further comprising the step of

scanning the full array after said inhibiting scan step in response to the detected signal strength of the sector to which the receiver is coupled reducing to a predetermined level for a predetermined time interval.

17. The method of claim 15 further comprising the step of:

squelching the receiver output except during the inhibiting scan step.

18. The method of claim 15 wherein the comparing step comprises the steps of:

(1) storing the peak signal strength level detected from each sector during scanning in a first storage array,

(2) storing a reference level for each sector in a second storage array, and

(3) comparing the value stored for each sector in the first array with those stored in second array and determining the condition of at least one sector having a signal in its first array exceeding its reference level in the second array by a predetermined amount to thereby activate the continuing scan step.

19. The method of claim 18 wherein the step of scanning only selected sectors comprises the steps of:

(a) selecting for further scan that sector whose first array stored signal exceeds its second array reference level by the greatest amount and

(b) selecting for further scan those sectors which are in a predetermined orientation with respect to said selected sector.

20. The method of claim 18 wherein the step of inhibiting scan further comprises the step of coupling the receiver to that one of the selected sectors whose first array stored signal exceeds its second array reference level by the greatest amount.

21. The method of claim 15 wherein the inhibiting scan step comprises the steps of:

(a) detecting the presence of a coded signal on the selected sector radio frequency signal,

(b) inhibiting scan if said selected sector signal contains said coded signal, and

(c) reverting to the step of scanning the full array if said selected sector signal fails to contain said coded signal.

22. The method of claim 18 wherein the inhibiting scan step comprises the steps of:

(a) detecting the presence of a coded signal on the selected sector radio frequency signal,

(b) inhibiting scan if said selected sector signal contains said coded signal, and

(c) reverting to the step of scanning the full array if said selected sector signal fails to contain said coded signal.

23. The method of claim 22 wherein the comparing step comprises the further step of:

transferring the stored peak signal strength levels from the first storage array to the second storage array such that said transferred signals become the reference levels, in response to the inhibiting scan step reverting to the step of scanning the full array as a result of the selected sector signal initially failing to contain said coded signal.

24. The method of claim 22 or 23 wherein the comparing step comprises the further step of:

zeroing the first storage array in response to the inhibiting scan step reverting to the step of scanning the full array as a result of the loss of said coded signal from the selected sector signal for a predetermined period of time.

25. The method of claim 23 wherein the comparing step further comprises the step of

periodically transferring the first array stored signal strength levels to the second storage array, such that the transferred signals become the reference level signals, during the step of scanning the full array.

26. The method of claim 23 or 25 wherein the transferring step further comprises:

a nonlinear transformation of the first array stored signal strength levels while said first array levels are being transferred to the second storage array such that the transfer is nonlinear.

27. The method of receiving radio frequency signals with a multisectored antenna array and a receiver, comprising the steps of:

(a) scanning the full array by sequentially sampling the radio frequency signal from each sector;

(b) detecting the strength of the sampled signal from each sector;

(c) comparing said signal strengths to a reference level and determining whether the signal strength level of at least one sector exceeds said reference level, and periodically updating the reference level utilizing a nonlinear transformation of the sampled signal from each sector;

(d) continuing scan of the antenna sectors for a time interval subsequent to determining that a sector signal strength exceeds said reference level;

(e) inhibiting scan following said time interval and coupling the receiver to a selected one of the antenna sectors.

28. The method of claim 27 further comprising the step of:

scanning the full array after said inhibiting scan step in response to the detected signal strength of the sector to which the receiver is coupled reducing to a predetermined level for a predetermined time interval.

29. The method of claim 27 further comprising the step of:

squelching the receiver output except during the inhibiting scan step.

30. The method of claim 27 wherein the comparing step comprises the steps of:

(1) storing the peak signal strength level detected from each sector during scanning in a first storage array,

(2) storing a reference level for each sector in a second storage array, and

(3) comparing the value stored for each sector in the first array with those stored in second array and determining the condition of at least one sector having a signal in its first array exceeding its reference level in the second array by a predetermined amount to thereby activate the continuing scan step.

31. The method of claim 30 wherein the step of inhibiting scan further comprises the step of coupling the receiver to that one of the selected sectors whose first array stored signal exceeds its second array reference level by the greatest amount.

32. The method of claim 27 wherein the inhibiting scan step comprises the steps of:

(a) detecting the presence of a coded signal on the selected sector radio frequency signal,

(b) inhibiting scan if said selected sector signal contains said coded signal, and

(c) reverting to the step of scanning the full array if said selected sector signal fails to contain said coded signal.

33. The method of claim 30 wherein the inhibiting scan step comprises the steps of:

(a) detecting the presence of a coded signal on the selected sector radio frequency signal,

(b) inhibiting scan if said selected sector signal contains said coded signal, and

(c) reverting to the step of scanning the fully array if said selected sector signal fails to contain said coded signal.

34. The method of claim 33 wherein the comparing step comprises the further step of:

transferring, utilizing the nonlinear transformation, the stored peak signal strength levels from the first storage array to the second storage array such that said transferred signals become the reference levels, in response to the inhibiting scan step reverting to the step of scanning the fully array as a result of the selected sector signal initially failing to contain said coded signal.

35. The method of claim 33 or 34 wherein the comparing step comprises the further step of:

zeroing the first storage array in response to the inhibiting scan step reverting to the step of scanning the full array as a result of the loss of said coded signal from the selected sector signal for a predetermined period of time.