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
  • H04B7/00—Radio transmission systems, i.e. using radiation field
  • H04B7/24—Radio transmission systems, i.e. using radiation field for communication between two or more posts
  • H04B7/26—Radio transmission systems, i.e. using radiation field for communication between two or more posts at least one of which is mobile
  • H04B7/2625—Radio transmission systems, i.e. using radiation field for communication between two or more posts at least one of which is mobile using common wave

Definitions

• This invention relates generally to simulcast radio communications systems.
• Simulcast radio communications systems are typically employed to provide wide area one-way or two- way radio communications services.
• a source site typically originates (or forwards from another originating site) a signal to be generally broadcast. This signal is routed from the source site to a plurality of remote sites. Each remote site then simultaneously broadcasts the signal with other remote sites to facilitate reception of the signal by receivers within the area covered by the system.
• a receiver outside the operating range of one remote site may still be within the range of one or more other remote sites, thereby reasonably ensuring that the receiver can receive the signal.
• One particularly dif icult problem with such simulcast systems involves coordinating the various remote sites to ensure that the signals are in fact substantially simultaneously broadcast by each. A failure to accomplish this will result in instances of unacceptable reception coherence as potentially caused by phase offsets, deviation, distortion and the like.
• the system includes generally a source site for providing an original signal to be broadcast, and a plurality of remote sites for substantially simultaneously broadcasting the original signal from the source site.
• the source site provides both a first and a second signal (such as voice and data) .
• the source site provides these two signals to the remote sites discrete from one another. Only after reception and appropriate processing at the remote site will the two signals be combined to facilitate their broadcast.
• the appropriate processing provided to the first and second signals at the remote sites includes introduction of an appropriate time delay to ensure that all of the remote sites broadcast substantially the same signal with substantially the same phase relationship.
• a monitoring device can be provided to monitor broadcast signals from the remote sites, and determine whether the broadcast signals exhibit an acceptable reception coherence. One or more broadcast system parameters can then be automatically varied in response to this determination as appropriate to improve reception coherence.
• Fig. 1 comprises a block diagram depiction of source site structure
• Fig. 2 comprises a block diagram depiction of remote site structure
• Fig. 3 comprises a block diagram depiction of the remote delay module of the remote site.
• Fig. 4 comprises a block diagram depiction of a monitoring site.
• the invention includes generally a source site unit (SSU) (100) (Fig. 1) and a remote site unit (RSU) (200) (Fig. 2) .
• the SSU (100) includes generally a microwave radio (101) that receives both audio and data input.
• the microwave radio (101) functions to transmit the two incoming signals in a known multiplexed manner to the RSUs (200) as described below in more detail.
• the SSU audio path (102) includes an audio source input (103) (which may be on site or off, as may be appropriate to the application or function) that passes through a transmission block (104) configured in known manner as a double sideband/reduced carrier, the output of which transmitter (104) couples to a transmitter input port of the microwave radio (101) .
• this input (103) could alternatively receive high speed data, such as control channel signalling.
• the data path (105) includes a data source (106) (which provides, for example, low speed data intended to be ultimately coupled subaudibly with the audio information) .
• the data source (106) passes through an FSK modulator (107) to a single sideband configured transmitter (108) .
• the latter transmitter (108) sums to a transmit port of the microwave radio (101) .
• the audio signal can be a first signal
• the data signal can be a second signal
• the radio Upon reception, the radio will render the voice information audible, and will subaudibly process and act accordingly upon the data information or instructions.
• the first and second signals are not combined at the SSU (100). Instead, they are transmitted separately and discrete from one another, in a multiplexed manner, to the RSUs (2o ⁇ ) .
• Fig. 2 an example RSU (200) will be described.
• the RSU (200) includes a repeater structure comprised of two microwave radios (201 and 202) . Signals received by the first microwave radio
• radios (201 and 202) function in a known manner to receive and transmit multiplexed signals, including the first and second signals provided by the SSU (100) .
• the RSU (200) also includes a combiner (203) as
• the combiner provides a high frequency received information line (204) and a high frequency transmit information line (205) .
• a single sideband configured receiver (206) couples to the receive line (204) and functions to receive the data information
• A-double sideband/reduced carrier configurated receiver (207) also couples to the receive line (204) and functions to receive the audio information as separately transmitted by the SSU (100) .
• the output of both receivers (206 and 207) is provided to a remote delay module (RDM) (208) , the configuration and operation of which will be described in more detail below.
• RDM remote delay module
• the output (209) of the remote delay module includes recovered audio information and recovered
• This combined signal can then be provided to appropriate transmitter equipment to allow a general broadcast of the information in a known manner.
• the RSU (200) also includes a single sideband
• transceiver (210) that couples to both high frequency lines of the combiner (203) and communicates with a processor unit (211) that provides appropriate control instructions to the RDM (208) as also described in more detail below.
• the RDM (208) includes a data path (301) and an audio path (302) .
• the data path (301) couples to the output of the single sideband receiver (206) through a 600 ohm input unit ( 03), following which the signal is appropriately clipped and squared (304) in a known manner.
• the data signal is then passed through an appropriate delay unit (305) .
• the delay unit (305) introduces a time delay in any appropriate known manner to accomplish a predetermined delay of propagation of the data signal to the transmitter of the RSU (200) . (The purpose of this delay is to ensure that all RSUs (200) transmit a given source signal as provided by the SSU (100) at substantially the same time.
• the delayed data signal then passes through an appropriate FS decoder (306) and subaudible data splatter filter (307) to a digital -attenuator unit (308). Following appropriate attenuation as required to provide necessary equalization, the data signal is provided to a summing unit (309) , the operation of which will be disclosed in more detail below.
• the audio path (302) connects to the output of the double sideband/reduced carrier receiver (207) through an appropriate 600 ohm input (310) .
• the audio signal is then passed through an appropriate anti-alias filter (311) to a delay unit (312) , the function and purpose of which is the same as that described above for the data path delay unit (305) .
• the audio signal passes through an appropriate splatter filter (313) and digital attenuator (314) to provide the necessary equalization, following which the signal passes through a highpass filter (315) to the summing unit (309) .
• the summing unit (309) functions to sum the delayed and properly processed data signals with the delayed and properly processed audio signals to thereby provide a composite signal.
• This composite signal then passes through an appropriate 600 ohm output unit (316) for subsequent processing (209) as referenced above.
• the audio path (302) may receive high speed data instead of voice information.
• the inputs to the summing unit (309) can be controlled by a number of logic gates (317, 318, and 319) that respond to an appropriate control signal (320) . So configured, the summing unit (309) will receive either both high pass filtered audio information and low speed data, or high speed data only that has not been high pass filtered. )
• the signal processing such as equalization and introduction of delay, occur at the RSU (200) as versus the SSU (100) .
• the first and second signals are individually and separately provided with the. appropriate delay and other signal compensation factors prior to their combination.
• Fig. 3 it can also be seen that the delay units (305 and 312) and the digital attenuators (308 and 314) can be controlled by the processor (211) referenced above.
• the processor (211) in turn can receive data information and/or instructions from the SSU (100) through the microwave radio link.
• instructions regarding the appropriate delay and attenuation can be formulated at the SSU (100) and transmitted to the various RSUs (200) , and implemented without human intervention.
• a monitoring site (400) in accordance with the invention can be seen as depicted generally by the numeral 400.
• a typical monitoring site includes a signal processing unit (401) that could include, for example, a number of directional antennas (402) . Each antenna (402) could be directed to a particular RSU (200) .
• the signal processing unit (401) utilizes that information to develop information regarding reception coherence for signals broadcast by the RSUs (200) .
• a processor (403) can be provided that takes the reception coherence information developed by the signal processing unit (401) and compares it against an appropriate threshold or other criteria. Information regarding the comparisons developed by the processor (403) can be transmitted via an appropriate radio (404) or other link to the SSU (100) or other control location. Based upon information developed by the monitoring site (400) regarding reception coherence, the delay and/or attenuation parameters for a given RSU (200) can be selectively varied to accommodate changing operating or environmental conditions.

Landscapes

• Engineering & Computer Science (AREA)
• Signal Processing (AREA)
• Computer Networks & Wireless Communication (AREA)
• Radio Relay Systems (AREA)
• Input Circuits Of Receivers And Coupling Of Receivers And Audio Equipment (AREA)
• Diaphragms For Electromechanical Transducers (AREA)
• Cable Transmission Systems, Equalization Of Radio And Reduction Of Echo (AREA)
• Mobile Radio Communication Systems (AREA)

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Publications (2)

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Citations (2)

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• 1989
  • 1989-08-22 CA CA000608982A patent/CA1306502C/fr not_active Expired - Lifetime
  • 1989-09-22 AU AU44853/89A patent/AU620939B2/en not_active Ceased
  • 1989-09-22 WO PCT/US1989/004059 patent/WO1990004889A1/fr not_active Application Discontinuation
  • 1989-09-22 BR BR898907727A patent/BR8907727A/pt unknown
  • 1989-09-22 EP EP19890912074 patent/EP0439515A4/en not_active Withdrawn
• 1992
  • 1992-01-28 CA CA000616300A patent/CA1316985C/fr not_active Expired - Fee Related

Patent Citations (2)

Non-Patent Citations (1)

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