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WO1997039541A1 - Systeme de commande d'emission utilisant la signalisation multifrequence - Google Patents

Systeme de commande d'emission utilisant la signalisation multifrequence Download PDF

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Publication number
WO1997039541A1
WO1997039541A1 PCT/US1997/005893 US9705893W WO9739541A1 WO 1997039541 A1 WO1997039541 A1 WO 1997039541A1 US 9705893 W US9705893 W US 9705893W WO 9739541 A1 WO9739541 A1 WO 9739541A1
Authority
WO
WIPO (PCT)
Prior art keywords
tone
control
spectral region
band
signals
Prior art date
Application number
PCT/US1997/005893
Other languages
English (en)
Inventor
Steven Pfiefer
Donald R. Bauman
James K. Lyon
Original Assignee
E.F. Johnson Company
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
Priority claimed from US08/631,866 external-priority patent/US5896560A/en
Priority claimed from US08/628,981 external-priority patent/US5991309A/en
Application filed by E.F. Johnson Company filed Critical E.F. Johnson Company
Priority to AU26629/97A priority Critical patent/AU2662997A/en
Publication of WO1997039541A1 publication Critical patent/WO1997039541A1/fr

Links

Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04H—BROADCAST COMMUNICATION
    • H04H20/00—Arrangements for broadcast or for distribution combined with broadcast
    • H04H20/65—Arrangements characterised by transmission systems for broadcast
    • H04H20/67—Common-wave systems, i.e. using separate transmitters operating on substantially the same frequency
    • 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
    • H04B1/60—Supervising unattended repeaters
    • 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
    • H04B1/68—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 for wholly or partially suppressing the carrier or one side band
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L12/00—Data switching networks
    • H04L12/02—Details
    • H04L12/12—Arrangements for remote connection or disconnection of substations or of equipment thereof
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04W—WIRELESS COMMUNICATION NETWORKS
    • H04W84/00—Network topologies
    • H04W84/02—Hierarchically pre-organised networks, e.g. paging networks, cellular networks, WLAN [Wireless Local Area Network] or WLL [Wireless Local Loop]
    • H04W84/04—Large scale networks; Deep hierarchical networks
    • H04W84/08—Trunked mobile radio systems

Definitions

  • the present invention relates generally to remote control using in-band signalling and in particular to transmit control and link control using in-band tone signalling in a distributed radio transmission system.
  • repeater based systems for a variety of radio frequency communications.
  • Advanced repeater systems must coordinate communications between a number of repeaters.
  • the repeaters may be linked together using a variety of inter-repeater communications means.
  • a remote subscriber such as a mobile radio user, will request a channel to transmit information to other subscribers and other services connected to the repeater system.
  • the repeater system manages the channels and provides a free channel to the calling subscriber.
  • the present invention is a system for controlling one or more remote sites using an in-band signalling tone and a specialized detection system.
  • the remote sites include transmitters which are disabled when a signalling tone is received. Receipt of the signalling tone indicates that no transmissions by the central site are in progress. Once the signalling tone is extinguished, the transmitters are activated to broadcast information sent by the central site.
  • the detection system located at each remote site monitors energy residing in the spectral region assigned to one or more in-band signalling tones. If a signal is detected in this spectral region, then energy in another spectral region is measured to determine if the signals are signalling tones or harmonics of voice or data information being transmitted by the system. If the energy in the data and voice portions of the spectrum is relatively low, then the system is receiving a signalling tone, and the transmitters are disabled.
  • One embodiment ofthe present transmit control system monitors data transmissions made by the repeater system to determine whether the signal received in the spectral range ofthe signalling tone is actually a signalling tone or harmonic noise.
  • One embodiment of the present transmit control system monitors signals in the voice band of interest to verify the signal received in the spectral range of the signalling tone.
  • Figure 1 is a block diagram showing one environment in which the present transmit control system may be practiced:
  • Figure 2 is one example of a transmit control module according to one embodiment of the present invention;
  • Figure 3 is one example of a link control module according to one embodiment of the present invention;
  • Figure 4 is a flow chart of the operation of one embodiment of a central site control system
  • Figure 5 is a flow chart ofthe operation of one embodiment of a remote site control system
  • Figure 6 shows a link state diagram, according to one embodiment ofthe present invention.
  • Figure 7 shows a transmit state diagram, according to one embodiment of the present invention.
  • Figure 8 shows a transmit state diagram, according to one embodiment of the present invention.
  • Figure 9 is a timing diagram showing the operation of one embodiment of the present transmit control system
  • Figure 10 is a timing diagram showing one embodiment of a two stage detection system
  • Figure 11 is an example of the operation of one application of the present transmit control system
  • Figure 12 is one example of an in-band tone detection system according to one embodiment ofthe present transmit control system
  • Figure 13 is one example of the audio portion of the central site controller according to one embodiment ofthe present invention.
  • Figure 14 is one example ofthe audio portion ofthe remote site controller according to one embodiment of the present invention. Detailed Description
  • links 120A-N are digital Tl links.
  • links 120 A-N are line of sight optical links. Other types of links may be used without departing from the scope and spirit ofthe present invention.
  • the remote sites A-N are remote repeaters which receive information from central site 1 10 and retransmit the information to a plurality of (mobile) subscriber units (not shown). Such systems often transmit voice signals and data signals between the subscriber units and the remote sites.
  • the transmissions include audio (300 Hz to 3 KHz) plus supervisory tone data, audio (300 Hz to 3 KHz) plus low speed (3.0 to 3.3 KHz) data which may be shifted upband, and high speed data (300 Hz to 3 KHz).
  • audio 300 Hz to 3 KHz
  • supervisory tone data audio (300 Hz to 3 KHz) plus low speed (3.0 to 3.3 KHz) data which may be shifted upband
  • high speed data 300 Hz to 3 KHz
  • an in-band tone control is used by the central site 1 10 to control the remote sites A-N.
  • the presence or absence of an in-band tone generated by the control site 1 10 is detected at the remote sites A-N.
  • the tone should not be present during a call.
  • a tone is transmitted by the central site when the central site 1 10 has no information to broadcast over the remote sites A-N. When the tone is absent the central site 1 10 has information to transmit to the remote sites.
  • This embodiment also has the advantage of working with any link, since the tone is in-band, and the tone generation and detection modules are independent ofthe link.
  • False signalling is a condition where the detection module erroneously detects a signal which is not the in-band transmit control tone.
  • Signal blocking is the condition where the detection module fails to detect the in-band transmit control tone due to interference with other information transmitted over the link. Both effects are competing, since as the sensitivity of the detection module is increased the likelihood of signal blocking diminishes, but the false signalling likelihood increases. Also if the detection module sensitivity decreases, then the false signalling effect is decreased and the signal blocking effect increases. Therefore, the present in-band tone control system must provide features to balance the false signalling and signal blocking effects.
  • the present control system decreases signal blocking by using an in-band tone in a frequency portion which is not within the high energy portion ofthe voice spectrum. Most of voice energy lies between 500 to 700 Hz with harmonics falling off in frequency. Some link systems do not transmit the lower frequency ranges (such as 0-300 Hz), therefore one embodiment of the present system uses a 2600 Hz tone. Other tones may be used, provided they are not within the statistically high energy portion ofthe transmissions and the tones arc within the bandpass range of the link. False signalling is reduced since the detection module detects the control tone and then investigates energy in other spectral portions to ensure that the detected tone is not a harmonic (or subharmonic) of the audio signals transmitted over the link (in this example, voice signals).
  • the 2600 Hz tone is detected and substantial energy is detected in the 1300 Hz and 650 Hz spectral portions, then it is likely that the 2600 Hz signal is really voice or data energy. If the energy detected in the 1300 Hz and 650 Hz spectral portions is relatively minor, then it is likely that the 2600 Hz tone is the control tone and not voice or data energy.
  • Another check is to compare the energy in the 2600 Hz frequency range with the energy found in the remaining portion ofthe link passband to determine if the 2600 Hz signal is truly the control signal. In one embodiment this is achieved using a notch passband filter to detect the 2600 Hz signal and a notch stopband filter to detect the remaining spectral range.
  • This embodiment of the present transmit control system monitors energy in the spectral region of the control tone and absence of energy in other spectral regions to determine whether the control signal is present.
  • Figure 2 shows the inputs and outputs for one embodiment ofthe in-band tone transmit control module. The permutations for this embodiment are provided in Table I.
  • the data frequency range may be used as the "other spectral region" energy to detect whether a call is being handled by the system.
  • FIG. 4 shows tone generation at the central site 1 10 according to one embodiment of the present invention.
  • the tone generator is enabled 410 and the call state ofthe system is set to idle 420. If a subscriber unit is requesting a transmission then the central site 1 10 deactivates the tone generator 440 and sets the call state to transmitting 450. If no transmission was requested by the subscriber unit 460 the call state remains idle and the central site continues looping until a transmission is requested. After a transmission has been initiated the tone is inhibited during the call 495 and until the transmission is done 480, 490.
  • Figure 5 shows one embodiment of the transmit control system wherein data is used as the "other spectral region" signal.
  • data is used as the "other spectral region" signal.
  • the call state is set to idle 505. If a tone is detected 510 but there is no other wideband energy (a data signal in this example) 515 then the state remains idle and the tone indicates no transmission. Once the tone is absent or a data signal is detected 520 the transmitter is enabled 526 and the call state is changed to transmitting 528. The system remains in this state until a tone is again detected 532 and no transmission energy (data energy, in this example) is detected 534. Upon receipt of a tone and no other data the transmitter is disabled 542 and the call state reverts to idle 544. It should be noted that the data energy of this example could be substituted with any other signal energy, such as voice band energy, as long as it is not the tone energy, without departing from the scope and spirit ofthe present invention.
  • the link control module provides information as to whether the link is up or down.
  • the link control module also provides a signal to an alarm module for failure alarm purposes.
  • the link control module detects wideband energy, which is any energy within the passband ofthe link.
  • wideband energy is energy from the signalling tone and when a call is present it is low-speed data energy (provided the system transmits low speed data during calls).
  • the link is determined to be "up” whenever there is wideband energy and “down” if there is no wideband energy.
  • Figure 3 shows one embodiment where signals representing energy in the spectral vicinity of the control tone and energy in the data spectral region are logically "ORed” to indicate wideband energy.
  • This embodiment uses the control tone energy and data energy signals used by the transmit control module, and is an example of an alternate system for link control. Again, the link is determined to be “up” whenever there is wideband energy and “down” if there is no wideband energy.
  • Alternate embodiments provide link control using parameters independent ofthe transmit control parameters.
  • Measurement of wideband energy is relatively straightforward for a continuous tone, however for data signals, the measurement may fluctuate.
  • the wideband energy is monitored over the interval of approximately one second to determine if wideband energy is present. Other times may be used so long as the link control signal is not substantially delayed.
  • Figure 6 shows one embodiment in which the link is "up" as long as the wideband energy is present, and "down" when it is absent.
  • Figure 7 shows a transmit control state diagram according to one embodiment ofthe present system which incorporates tone info ⁇ nation and link information into enabling or disabling the transmitter.
  • Figure 8 shows an alternate embodiment which incorporates wideband energy as well as tone and link information.
  • Figure 9 shows signals in one embodiment ofthe present invention and demonstrates the transmit control and link control of this embodiment.
  • Traces A and B demonstrate that the tone signal is inhibited when transmissions from the central site 1 10 are being performed.
  • Trace C illustrates how the system functions during a link malfunction.
  • the central site 1 10 data (trace D) and voice (trace E) are transmitted to the remote site when the remote site tone is inhibited (trace E).
  • the data and voice information received by the remote site is as good as the link quality (traces G and H).
  • the remote site wideband energy, trace 1 is the logical OR ofthe remote site tone (F) and remote site data (G) (for purposes of this example, the data and voice transmissions are overlapping in time, yet this may differ in other systems. In those systems the wideband energy would have to be the logical OR of traces F, G, and H.)
  • the tone detection is provided by a bandpass filter, rectifier, low pass filter, and threshold comparison.
  • the bandpass filter output and the low pass filter output are compared to determine whether the tone is present and the other transmissions are absent.
  • Another embodiment inco ⁇ orates a digital signal processor (DSP) executing a Discrete Fourier Transform (DFT) to detect the tone, since a single tone is used to inhibit the transmissions.
  • DSP digital signal processor
  • DFT Discrete Fourier Transform
  • a Fast Fourier Transform (FFT) calculates the entire spectrum for N samples and involved N log N complex computations. The DFT only requires N 2 complex computations generally. But for a single frequency, it requires only N complex computations.
  • Another embodiment uses a modification of a Goertzel algorithm executing on a DSP, followed by direct threshold comparison, to perform a time to frequency transformation of the input signal and compare the tone frequency with other frequencies in the signal.
  • This provides an efficient spectral comparison ofthe elements of the signal arriving from the central site 1 10.
  • the modified Goertzel algorithm is described in the book entitled “Digital Signal Processing Applications", Volume 1 of 2, by Analog Devices, Inc. 1992.
  • the modified Goertzel algorithm is described in detail in pages 457 to 465. This method involves a repeated operation of a feedback method and a feedforward method, which is used to generate a result indicating the energy present in a spectral region of interest.
  • the modified Goertzel algorithm simplifies calculations by the DSP and increase the efficiency and speed ofthe tone detection.
  • This system squares all terms and computes the magnitude squared of the frequency of interest, which reduces each complex coefficient of the calculation to a single real coefficient.
  • the single real coefficient may be used to calculate every term of the summation.
  • This system also operates on samples as they are input into the system which increases throughput of the DSP.
  • Figure 10 shows the benefits of signal filtering ofthe transmitter signal to prevent short toggling ofthe transmitter at the remote site (traces A-D).
  • the input signal (A) is compared to generate an absence signal (B).
  • the absence signal is integrated (C) and digitized (D) to produce the switching signal shown in trace D.
  • the process creates a low frequency representation of the input signal to prevent toggling the output signal for minor variations in the input signal.
  • An integration of trace E is shown in Figure F, which is then digitized to produce trace G.
  • the averaging method creates an energy/tone detection which is substantially independent of the actual tone level.
  • Figure 11 demonstrates one example of a transmit control system.
  • a control signal of 2600 Hz is transmitted to the repealer by the central site to indicate an inactive transmission state.
  • the subscriber unit requests a channel for transmission from its local repeater.
  • Information about the subscriber unit's request is transmitted by the repeater to the channel controller at the central site over the link. II " the controller verifies that the channel is free, the channel controller terminates the control signal.
  • the repeater detects the loss of the control signal and activates the transmitter.
  • the central controller then transmits control and voice information to the repeater for rebroadcast by the repeater.
  • FIG 12 shows one embodiment of a DSP system for control signal detection.
  • DSP 56002 executes the modified Goertzel algorithm and detects the tone transmission from the central controller.
  • Data signals are monitored as the second source of spectral information and are used in the control systems shown in Figure 5 and described above. Further details of the audio block diagram are provided in Figures 13 and 14, at the central controller site and remote site, respectively.

Landscapes

  • Engineering & Computer Science (AREA)
  • Signal Processing (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Radio Relay Systems (AREA)
  • Position Fixing By Use Of Radio Waves (AREA)
  • Testing, Inspecting, Measuring Of Stereoscopic Televisions And Televisions (AREA)
  • Mobile Radio Communication Systems (AREA)
  • Selective Calling Equipment (AREA)

Abstract

Un système de commande d'émission utilise des tonalités dans la bande pour activer et désactiver un ou plusieurs sites éloignés. Le système de commande détecte l'énergie dans deux zones du spectre ou plus afin de déterminer si le signal reçu est un signal harmonique ou une fréquence de signalisation, de façon à empêcher la désactivation accidentelle du système émetteur. Dans l'une des applications, un processeur de signaux numérique utilise un algorithme de Goertzel modifié, pour assurer la détection des fréquences, et un système de détection à deux niveaux assure la commutation commandée dans les environnements bruyants.
PCT/US1997/005893 1996-04-12 1997-04-11 Systeme de commande d'emission utilisant la signalisation multifrequence WO1997039541A1 (fr)

Priority Applications (1)

Application Number Priority Date Filing Date Title
AU26629/97A AU2662997A (en) 1996-04-12 1997-04-11 Transmit control system using control tone signalling

Applications Claiming Priority (12)

Application Number Priority Date Filing Date Title
US63067396A 1996-04-12 1996-04-12
US1530996P 1996-04-12 1996-04-12
US1531196P 1996-04-12 1996-04-12
US08/630,673 1996-04-12
US60/015,311 1996-04-12
US08/631,866 US5896560A (en) 1996-04-12 1996-04-12 Transmit control system using in-band tone signalling
US08/628,981 US5991309A (en) 1996-04-12 1996-04-12 Bandwidth management system for a remote repeater network
US08/628,981 1996-04-12
US08/631,866 1996-04-12
US60/015,309 1996-04-12
US2776396P 1996-10-07 1996-10-07
US60/027,763 1996-10-07

Publications (1)

Publication Number Publication Date
WO1997039541A1 true WO1997039541A1 (fr) 1997-10-23

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Family Applications (4)

Application Number Title Priority Date Filing Date
PCT/US1997/005893 WO1997039541A1 (fr) 1996-04-12 1997-04-11 Systeme de commande d'emission utilisant la signalisation multifrequence
PCT/US1997/005985 WO1997039535A2 (fr) 1996-04-12 1997-04-11 Systeme de gestion des largeurs de bande pour un reseau a repeteurs tele-alimentes
PCT/US1997/005984 WO1997039543A2 (fr) 1996-04-12 1997-04-11 Systeme de calcul de temporisation de liaison pour un systeme de repeteurs radio
PCT/US1997/005891 WO1997039542A2 (fr) 1996-04-12 1997-04-11 Systeme de gestion de la radiodiffusion par reseau d'emetteurs

Family Applications After (3)

Application Number Title Priority Date Filing Date
PCT/US1997/005985 WO1997039535A2 (fr) 1996-04-12 1997-04-11 Systeme de gestion des largeurs de bande pour un reseau a repeteurs tele-alimentes
PCT/US1997/005984 WO1997039543A2 (fr) 1996-04-12 1997-04-11 Systeme de calcul de temporisation de liaison pour un systeme de repeteurs radio
PCT/US1997/005891 WO1997039542A2 (fr) 1996-04-12 1997-04-11 Systeme de gestion de la radiodiffusion par reseau d'emetteurs

Country Status (2)

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AU (4) AU2662997A (fr)
WO (4) WO1997039541A1 (fr)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6674855B1 (en) 1999-10-06 2004-01-06 Comverse Ltd. High performance multifrequency signal detection

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN108519738A (zh) * 2018-04-13 2018-09-11 中国科学院微电子研究所 一种车辆运动状态信息延时补偿方法和装置

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US5184242A (en) * 1989-12-15 1993-02-02 Nec Corporation Supervisory circuit for optical repeater

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US4406016A (en) * 1981-11-27 1983-09-20 The United States Of America As Represented By The Secretary Of The Army VHF Sensor in-band radio relay
US5184242A (en) * 1989-12-15 1993-02-02 Nec Corporation Supervisory circuit for optical repeater

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US6674855B1 (en) 1999-10-06 2004-01-06 Comverse Ltd. High performance multifrequency signal detection

Also Published As

Publication number Publication date
AU2450297A (en) 1997-11-07
WO1997039543A2 (fr) 1997-10-23
WO1997039535A3 (fr) 1997-12-24
WO1997039543A3 (fr) 1998-02-05
WO1997039535A2 (fr) 1997-10-23
AU2726397A (en) 1997-11-07
WO1997039542A3 (fr) 2001-09-13
AU2662997A (en) 1997-11-07
WO1997039542A2 (fr) 1997-10-23
AU2726297A (en) 1997-11-07

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