WO2008115363A1 - Système et procédé de détection d'impulsions à large bande parmi de nombreux émetteurs brouilleurs au moyen d'un récepteur de filtre dynamique - Google Patents

Système et procédé de détection d'impulsions à large bande parmi de nombreux émetteurs brouilleurs au moyen d'un récepteur de filtre dynamique Download PDF

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Publication number
WO2008115363A1
WO2008115363A1 PCT/US2008/003129 US2008003129W WO2008115363A1 WO 2008115363 A1 WO2008115363 A1 WO 2008115363A1 US 2008003129 W US2008003129 W US 2008003129W WO 2008115363 A1 WO2008115363 A1 WO 2008115363A1
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WO
WIPO (PCT)
Prior art keywords
power
sample
signals
pulse
narrow band
Prior art date
Application number
PCT/US2008/003129
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English (en)
Inventor
Joseph Bobier
Original Assignee
Xg Technology, Inc.
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Xg Technology, Inc. filed Critical Xg Technology, Inc.
Priority claimed from US12/075,239 external-priority patent/US8094759B2/en
Publication of WO2008115363A1 publication Critical patent/WO2008115363A1/fr

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Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
    • H04B1/06—Receivers
    • H04B1/10—Means associated with receiver for limiting or suppressing noise or interference
    • H04B1/1027—Means associated with receiver for limiting or suppressing noise or interference assessing signal quality or detecting noise/interference for the received signal
    • H04B1/1036—Means associated with receiver for limiting or suppressing noise or interference assessing signal quality or detecting noise/interference for the received signal with automatic suppression of narrow band noise or interference, e.g. by using tuneable notch filters

Definitions

  • This invention addresses the need to transport high bit-rate data over wired or wireless means using specially modulated radio frequency carrier waves. Specifically, This disclosure describes a new method of detection of broadband pulses in the presence of multiple strong narrow band interferers.
  • Modulation is the fundamental process in any communication system. It is a process to impress a message (voice, image, data, etc.) on to a carrier wave for transmission.
  • a band-limited range of frequencies that comprise the message (baseband) is translated to a higher range of frequencies.
  • the band-limited message is preserved, i.e., every frequency in that message is scaled by a constant value.
  • the three key parameters of a carrier wave are its amplitude, its phase and its frequency, all of which can be modified in accordance with an information signal to obtain the modulated signal.
  • modulators There are various shapes and forms of modulators.
  • conventional Amplitude Modulation uses a number of different techniques for modulating the amplitude of the carrier in accordance with the information signal. These techniques have been described in detail in "Modern Analog and Digital Communication Systems" by B.P. Lathi.
  • conventional Frequency / Phase Modulation uses a number of different methods described in a number of textbooks. In all these techniques, carrier (which is a high frequency sinusoidal signal) characteristics (either amplitude, frequency, phase or combination of these) are changed in accordance with the data (or information signal).
  • carrier which is a high frequency sinusoidal signal
  • characteristics either amplitude, frequency, phase or combination of these
  • any interfering signal in that spectrum must be tolerated and mitigated within the receiver.
  • Many schemes exist to mitigate the interference Some of these include selective blocking of certain sections of spectrum so as not to hear the interferer, OFDM schemes that send redundant copies of the information in the hope that at least one copy will get through the interference, and other more exotic schemes that require sophisticated DSP algorithms to perform advanced filtering.
  • UWB systems have somewhat of a "bad reputation" because they at least have the potential to cause interference. A heated discourse has gone on for years over the potential that UWB systems can cause interference to legacy spectrum users.
  • Tri-State Integer Cycle Modulation (TICM) and other Integer Cycle Modulation techniques, which have now become known by its commercial designation, xMax, were designed by the inventor of this application to help alleviate this massive and growing problem. Its signal characteristics are such that absolute minimal sideband energy is generated during modulation but that its power spectrum density is quite wide relative to the information rate applied. Also, a narrower section of the power spectrum output can be used to represent the same information.
  • the technique of broadband pulse detection disclosed herein is primarily applicable to these types of integer cycle and pulse modulation systems.
  • the invention disclosed in this application uses any integer cycle or impulse type modulation and more particularly is designed to work with a method of modulation named Tri-State Integer Cycle Modulation (TICM) which has been previously disclosed in U.S. Patent No. 7,003,047 issued February 21, 2006, filed by the inventor of this disclosure and is now known by its commercial designation, xMax.
  • TAM Tri-State Integer Cycle Modulation
  • Pulse modulation is used in many forms and generally consists of a pulse of radio energy that can be as simple as On - Off Keying (OOK) to more complex systems like Pulse Position Modulation (PPM) and even more advanced systems such as xMax.
  • OOK On - Off Keying
  • PPM Pulse Position Modulation
  • the present invention outlines an improved method of detection of broadband pulses in the presence of multiple strong narrow band interferers (NBI).
  • NBI narrow band interferers
  • FIGURE 1 is a representation of the power spectrum of a pulse without NBI distortion
  • FIGURE 2 is a representation of the power spectrum of a pulse with NBI distortion
  • FIGURE 3 is a representation of a simple direct conversion integer cycle modulation receiver
  • FIGURE 4 is a representation of an integer cycle modulation rake receiver
  • FIGURE 5 is a representation of an integer cycle modulation DSP based sub- band receiver
  • FIGURE 6 is a representation of a four sub-band receiver output with 25% and 50% sub-band based loss due to NBI;
  • FIGURE 7 is a representation of a DSP based integer cycle modulation receiver block diagram
  • FIGURE 8 is a representation of an integer cycle modulation spectral plot with no interferers
  • FIGURE 9 is a representation of a 900 MHz spectral plot with random interferers
  • FIGURE 10 is a representation of a spectral plot with reference interferers and integer cycle modulation signal present
  • the radio spectrum can be considered one great radio channel.
  • the radio spectrum is subdivided into smaller channels, such division being the prerogative of government regulators.
  • Digital radio systems that are designed to deliver broadband data through such channels will use spectrum allocations set aside for such purposes. Such allocations might be specially allocated to licensed users and some radio spectrum is designated as unlicensed.
  • one section of the band is designated as the 900 MHz ISM (Industrial, Scientific and Medical) band.
  • ISM International, Scientific and Medical
  • Narrow-Band Integer Cycle or Impulse Modulation Spectrum Sharing Method filed February 24, 2006, US Application No 11/361,397, by the inventor of this disclosure.
  • NBI narrow band interferers
  • Such systems correlate the transmission of a single bit of information to the transmission of the briefest possible burst over the homogenous radio spectrum power possible.
  • Such systems not being based upon complex variations of phase, frequency or amplitude tend to be more resistant to noise and interferers. This can be thought of as a natural result since the now broad category of single cycle transmissions can be recognized as first order or base order modulation schemes. None the less, even first order systems are subject to interference, as all radio systems are.
  • the present invention will define an improved radio reception system that further improves the single cycle modulation (SCM) radio receivers' immunity to NBI.
  • SCM single cycle modulation
  • radio receivers used in the reception of SCM take various forms, some being more or less resistant to NBI.
  • the simplest, a direct conversion receiver shown in figure 3 receives the radio band in which the transmission takes place, filters out the external bands through band pass filters, amplifies the band to a level suitable for detection, and depends upon the detection of the time domain representation of the original transmitted pulse though use of a comparator threshold circuit.
  • the pulse threshold is compared to a reference level and pulses that exceed the reference threshold are considered as valid "1" bits. Since the coding scheme used transmits bits in a specific time frame and schedule, the presence of a pulse will represent a "1" and the lack of a pulse will represent a "0".
  • the second-generation receiver divides the band into multiple sub bands as shown in figure 4. Individual detectors at each sub band detect the SCM pulse, and the output of each sub band detector is ANDed to indicate the presence of the wide band signal.
  • a strong interferer might keep an individual sub band detection circuit in a continuous SIGNAL DETECTED mode, but only a simultaneous SIGNAL DETECTED output from all sub band detectors would constitute a valid pulse detection.
  • This system does increase the Signal to Interference Ratio (SIR) substantially.
  • SIR Signal to Interference Ratio
  • the amount of improvement depends upon the number of "fingers” involved in the subdivision process. Thus we have improved performance while increasing complexity of the circuitry.
  • DSP digital signal processor
  • the computing power of the DSP must be large enough to process enough sub bands to make the endeavor worth while. This increase of complexity, whether by discrete circuitry or DSP power contributes substantially to the cost of the receiver.
  • a third improvement to the reception of SCM signals was made when a mixer is added to the receiver to down convert the 900 MHz signal to an IF frequency.
  • an A/D converter digitizes the signal.
  • sub bands are formed using FIR filters. Now each sub band is analyzed by the DSP and any sub bands found to contain NBI are discarded. The surviving sub bands are then re- combined and a pulse can be detected in the time domain by the familiar threshold detector.
  • a correlator can be used to compare the reconstituted pulse to a stored pattern of ideal and non-ideal pulses to form a logical decision of PULSE DETECTED or NOT PULSE DETECTED.
  • This system does in fact further improve the receivers' susceptibility to NBI.
  • Using a moderately priced FPGA to perform the DSP function yields an SIR level of about -10 to -20 db. That is to say that the interferer can be as high as 20 db stronger than the SCM signal and still yield a good result.
  • the number of sub bands will determine the SIR performance. More sub bands will eliminate more interferers while limiting the damage to the broadband pulse, but at the added expense of DSP size and cost.
  • the present invention will define a new receiver paradigm that draws less on the DSP power, yet increases the number of NBI signals that can be tolerated and will increase the SIR level dramatically, thus decreasing cost and complexity while improving performance.
  • a block diagram of such a receiver called a Dynamic Filter Receiver is shown in figure 7.
  • the Dynamic Filter Receiver the receiver is again sensitive to the broadband radio channel. The channel is received, amplified, band pass filtered and converted to an IF frequency. Once the signal is converted, the EF is again band pass filtered to recover only the desired channel and then digitized via an A/D converter.
  • one of the core tenets of SCM is that pulses are either transmitted or not transmitted, according to the binary logic state of "1" or "0" at a specified time in a pre-arranged time schedule or "frame".
  • a spectral plot of an SCM pulse is shown in figure 8.
  • the receiver need not continuously sample the radio spectrum, but only needs to sample the spectrum during a short and pre-arranged time slot. Thus a "snapshot" of the radio band can be taken when we expect a transmission from the transmitter.
  • the band power can be sampled at a band location or frequency that is known to contain only SCM power. If the power level in the spectrum is higher than the power in the same un- filtered frequency or frequencies in the reference FFT, the symbol is considered to be a "1" as shown in figure 12. Otherwise the symbol is considered a "0" as shown in figure 11. Thus, nearly any number of NBI sources might exist in the channel, but they are narrow band in nature.

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  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Noise Elimination (AREA)

Abstract

L'invention concerne un système et un procédé permettant de détecter des impulsions à large bande en présence de plusieurs émetteurs brouilleurs à forte bande étroite; pour ce faire, on utilise un procédé de filtrage dynamique pour détecter et pour éliminer le signal d'interférence en formant des filtres coupe-bande à l'emplacement précis des émetteurs brouilleurs à bande étroite.
PCT/US2008/003129 2007-03-16 2008-03-10 Système et procédé de détection d'impulsions à large bande parmi de nombreux émetteurs brouilleurs au moyen d'un récepteur de filtre dynamique WO2008115363A1 (fr)

Applications Claiming Priority (4)

Application Number Priority Date Filing Date Title
US91849907P 2007-03-16 2007-03-16
US60/918,499 2007-03-16
US12/075,239 2008-03-10
US12/075,239 US8094759B2 (en) 2007-03-16 2008-03-10 System and method for broadband pulse detection among multiple interferers using a dynamic filter receiver

Publications (1)

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WO2008115363A1 true WO2008115363A1 (fr) 2008-09-25

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Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6020783A (en) * 1998-06-05 2000-02-01 Signal Technology Corporation RF notch filter having multiple notch and variable notch frequency characteristics
US6028850A (en) * 1998-07-10 2000-02-22 Hyundai Electronics America, Inc. Wireless transceiver and frequency plan
US20010033583A1 (en) * 1999-04-13 2001-10-25 Rabenko Theodore F. Voice gateway with downstream voice synchronization
US20030058558A1 (en) * 2001-08-22 2003-03-27 International Business Machines Corporation Adaptive dual-frequency notch filter
US20040042387A1 (en) * 1996-05-20 2004-03-04 Adc Telecommunications, Inc. Communication system with multicarrier telephony transport

Patent Citations (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20040042387A1 (en) * 1996-05-20 2004-03-04 Adc Telecommunications, Inc. Communication system with multicarrier telephony transport
US6020783A (en) * 1998-06-05 2000-02-01 Signal Technology Corporation RF notch filter having multiple notch and variable notch frequency characteristics
US6028850A (en) * 1998-07-10 2000-02-22 Hyundai Electronics America, Inc. Wireless transceiver and frequency plan
US20010033583A1 (en) * 1999-04-13 2001-10-25 Rabenko Theodore F. Voice gateway with downstream voice synchronization
US20030058558A1 (en) * 2001-08-22 2003-03-27 International Business Machines Corporation Adaptive dual-frequency notch filter

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