Best-of-M pulse position modulation detector

• US 5,666,379 A
• Filed: 06/06/1995
• Issued: 09/09/1997
• Est. Priority Date: 11/01/1993
• Status: Expired due to Term

• Current Assignee: Micron Technology, Inc.
• Original Assignee: Omnipoint Corp. (Deutsche Telekom AG)
• Inventors: Ovard, David, Jensen, Ryan N.
• Primary Examiner(s): Chin, Wellington
• Assistant Examiner(s): Tran, Congvan
• Application Number:
  US08/468,802
• Time in Patent Office: 826 Days
• Field of Search: 375/239, 375/200, 375/204, 375/206, 375/340, 327/22, 327/23, 327/26, 327/27, 329/313, 332/112, 370/10, 370/8, 370/213
• US Class Current: 375/239
• CPC Class Codes: H04B 1/707 using direct sequence modulation
• CPC Class Codes: H04B 14/026 using pulse time characteristics modulation, e.g. width, position, interval

Abstract

A pulse position modulation detector divides a timing window into a plurality of pulse position windows, determines the peak magnitude of a signal level received during each pulse position window, compares the peak magnitudes of the signal detected during each pulse position window to determine during which pulse position window the greatest peak magnitude is detected, and generates a bit sequence corresponding to the pulse position window wherein the greatest peak magnitude was detected within the current timing window.

Claims

1. A method of detecting a pulse in a pulse position modulated signal received by a receiving unit, comprising the steps of:

dividing a timing window into a plurality of pulse position windows;

for each of said pulse position windows, detecting a peak magnitude of the pulse position modulated signal received by said receiving unit;

comparing the peak magnitudes for said pulse position windows of the pulse modulated signal received by said receiving unit to identify a greatest peak magnitude and a one of said pulse position windows wherein said greatest peak magnitude was detected; and

generating a bit sequence associated with said one pulse position window.

2. The method of claim 1, further comprising the step of storing said greatest peak magnitude in a peak magnitude register.

3. A method for detecting a pulse in a plurality of pulse position modulated signals received by a receiving unit, comprising the steps of:

dividing a timing window into a plurality of pulse position windows;

detecting a peak magnitude for each of said pulse position modulated signals received by said receiving unit for each of said pulse position windows;

comparing the peak magnitudes for said pulse position modulated signals received by said receiving unit for each of said pulse position windows to identify a greatest peak magnitude and a one of said pulse position windows wherein said greatest peak magnitude was detected; and

generating a bit sequence associated with said one pulse position window.

4. The method of claim 3, further comprising the step of storing said greatest peak magnitude in a peak magnitude register.

5. The method of claim 3, further comprising the steps of:

identifying one of said pulse position modulated signals which generated said greatest peak magnitude; and

generating a data bit associated with said one pulse position modulated signal.

6. The method of claim 3, wherein said step of comparing the peak magnitudes for said pulse position modulated signals for each of said pulse position windows, comprises the steps of:

for each of said pulse position windows, comparing said peak magnitudes of said pulse position modulated signals to identify a composite peak magnitude; and

comparing said composite peak magnitudes for said pulse position windows to identify the greatest peak magnitude and the one of said pulse position windows wherein said greatest peak magnitude was detected.

7. An apparatus for detecting pulses communicated with pulse position modulation, said apparatus comprising:

a peak detector connected to a pulse position modulated signal and generating a sample peak magnitude signal during each of a plurality of predefined pulse position windows within a timing window;

a first latch and a second latch each connected to said sample peak magnitude signal, said first latch being transparent and said second latch being latched with a current peak magnitude signal;

a comparator connected to said first latch and said second latch and generating a comparator output signal; and

a control logic circuit connected to said comparator output signal and, in response thereto, latching one of said first latch and said second latch with the sample peak magnitude signal if said sample peak magnitude signal is greater than said current peak magnitude signal.

8. The apparatus of claim 7, further comprising a peak magnitude register connected to said sample peak magnitude signal and current peak magnitude signal, said control logic circuit storing said sample peak magnitude signal in said peak magnitude register if said sample peak magnitude signal is greater than said current peak magnitude signal.

9. A pulse position modulation detector comprising:

peak detection means connected to a pulse position modulated signal and generating a sample peak magnitude in each of a plurality of pulse position windows within a timing window;

comparison means comparing said sample peak magnitudes to identify a greatest peak magnitude and a one of said pulse position windows wherein said greatest peak magnitude was detected; and

bit generation means for generating a bit sequence associated with said one pulse position window.

10. The pulse position modulation detector of claim 9, further comprising peak magnitude storage means for storing and providing said greatest peak magnitude.

11. The pulse position modulation detector of claim 9, wherein said peak detection means comprises:

a peak detector connected to said pulse position modulated signal and generating a peak magnitude signal in each of a plurality of pulse position windows.

12. The pulse position modulation detector of claim 9, wherein said comparison means comprises:

a first latch being a transparent latch and a second latch being latched with a current peak magnitude signal;

a comparator connected to said first latch and said second latch and generating a comparator output signal; and

a control logic circuit connected to said comparator output signal and, in response thereto during each of said pulse position windows, latching one of said first latch and said second latch with the sample peak magnitude signal if said sample peak magnitude signal is greater than said greatest peak magnitude signal.

13. In a system for pulse position modulation communication wherein a timing window is divided into a plurality of pulse position windows, a pulse position modulation detector comprising:

a first peak detector connected to a first pulse position modulated signal and generating therefrom a first peak signal in each of said plurality of pulse position windows;

a second peak detector connected to a second input signal and generating therefrom a second peak signal in each of said plurality of pulse position windows;

peak signal selection means connected to said first peak signal and said second peak signal and selecting in each of the pulse position windows the greater of said first and second peak signals as a sample peak magnitude signal;

a first latch and a second latch each connected to the sample peak magnitude signal, one of said latches being transparent during each pulse position window and the other of said latches being latched with a current peak magnitude signal;

a first comparator connected to said sample peak magnitude signal and said current peak magnitude signal and generating a comparator output signal; and

a control logic circuit connected to said comparator output signal and, in response thereto, latching one of said first latch and said second latch with the sample peak magnitude signal if said sample peak magnitude signal is greater than said current peak magnitude signal.

14. The pulse position modulation detector of claim 13, further comprising a peak magnitude register connected to said sample peak magnitude signal and said current peak magnitude signal, said control logic circuit storing said sample peak magnitude signal in said peak magnitude register if said sample peak magnitude signal is greater than said current peak magnitude signal.

15. The pulse position modulation detector of claim 13 wherein said peak signal selection means comprises:

a first analog-to-digital converter connected to said first peak signal and generating a first digitized peak signal;

a second analog-to-digital converter connected to said second peak signal and generating a second digitized peak signal;

a second comparator connected to said first digitized peak signal and said second digitized peak signal, and generating a select signal indicating a one of said first and second digitized peak signals which is greater; and

a multiplexer connected to said select signal and selecting said one digitized peak signal as the sample peak magnitude signal.

16. The pulse position modulation detector of claim 13 wherein said peak signal selection means comprises:

an equal-gain diff-amp connected to said first peak signal and said second peak signal and generating a composite peak signal;

an analog-to-digital converter receiving the composite peak signal and generating therefrom a digitized peak signal; and

and XOR bank receiving the digitized peak signal and generating therefrom the sample peak magnitude signal.

17. The pulse position modulation detector of claim 13 wherein said peak signal selection means provides a peak selection signal to said control logic circuit identifying a one of said first and second peak signals which is greater, said control logic circuit producing therefrom a correlator data bit signal indicating a one of said first and second input signals which produced said one peak signal.

18. The pulse position modulation detector of claim 13, wherein said pulse position modulation detector is incorporated in a spread spectrum communication system further comprising a spread spectrum transmitter, comprising:

an input port connected to an input data signal;

a transmitter chip sequence generator generating a predetermined chip spreading sequence;

a spread spectrum pulse position modulator connected to said input data signal and said predetermined chip spreading sequence, and generating a spread spectrum pulse position modulated signal;

said spread spectrum communication system further comprising a spread spectrum receiver, comprising;

a receiver chip sequence generator generating said predetermined chip spreading sequence; and

a spread spectrum pulse position demodulator connected to said spread spectrum pulse position signal and said predetermined chip spreading sequence and generating a received data signal.