Modular transmission system and method

• US 6,023,612 A
• Filed: 07/03/1997
• Issued: 02/08/2000
• Est. Priority Date: 07/05/1996
• Status: Expired due to Term

• Current Assignee: Thales Broadcast & Multimedia Incorporated (Groupe Sipromad SA)
• Original Assignee: Thomcast Communications Incorporated (Groupe Sipromad SA)
• Inventors: Harris, Clifford, Correa, Paulo, Ungvarsky, Carl
• Primary Examiner(s): Eisenzopf, Reinhard J.
• Assistant Examiner(s): Fuller, Greta J.
• Application Number:
  US08/887,939
• Time in Patent Office: 950 Days
• Field of Search: 455/103, 455/115, 455/117, 455/126, 455/71, 455/127, 455/91, 324/76.46, 330/295, 330/124 R
• US Class Current: 455/127.1
• CPC Class Codes: H01P 1/2138 using hollow waveguide filters H01P1/2131 takes precedence
• CPC Class Codes: H01Q 3/267 Phased-array testing or checking devices
• CPC Class Codes: H03F 1/526 protecting by using redundant amplifiers
• CPC Class Codes: H03F 2200/294 the amplifier being a low noise amplifier [LNA]
• CPC Class Codes: H03F 2200/372 Noise reduction and elimination in amplifier
• CPC Class Codes: H03F 3/602 Combinations of several amplifiers
• CPC Class Codes: H03G 1/0088 using discontinuously variable devices, e.g. switch-operated
• CPC Class Codes: H03G 3/3042 in modulators, frequency-changers, transmitters or power amplifiers transmission power control in bidirectional transmission systems H04W52/04
• CPC Class Codes: H04L 1/22 using redundant apparatus to increase reliability
• CPC Class Codes: H04W 52/52 using AGC [Automatic Gain Control] circuits or amplifiers

Abstract

A modular broadband transmission system and method include an input signal connector that receives an input signal which is then divided into N parts and amplified with an amplifier have N power amplifier modules. Outputs of the N power amplifier modules are passed through transmission lines and to a radial combiner that combines the outputs. The radial combiner, transmission lines and power amplifier modules are configured such that if one of the power amplifier modules fails, the other power amplifier modules may still operate acceptable well, with minimal impact on total output power. An output of the amplifier is provided to a coupler that measures a power level of the output signal and feeds the measured power level back to a controller where the controller adjust an overall output power based on the number of the power amplifier modules that are functioning properly. Each of the power amplifier modules have a processor such that respective of the power amplifier modules may be taken off-line, and replaced while the other power amplifier modules continue to operate in a transmit mode of operation. The modular broadband transmission system and method may conveniently be used as either a broadband booster for amplifying a plurality of input signals, or a head and transmitter configured to amplify one or more different input signals.

Claims

1. A modular transmission system comprising:

an input signal connector configured to be connected to a signal source and receive an input signal therefrom;

a modular amplifier comprising,

a divider circuit that divides said input signal into a plurality of divided signals, and

N power amplifier modules, each configured to receive and amplify at least one of said divided signals and to provide a corresponding amplified output signal, N being an integer greater than or equal to two;

a plurality of transmission lines, each having a first end coupled to a corresponding one of said N power amplifier modules and configured to couple respective amplified output signals therefrom, said plurality of transmission lines each having a second end;

a radial combiner comprising N radial combiner input terminals coupled to respective of said second ends of said transmission lines, said radial combiner having an output connector through which an output signal is output within a predetermined output power level range; and

a controller coupled to said amplifier and configured to keep said output signal within said predetermined output power level range, where said predetermined output power range is based on the number of the amplified output signals applied to said N radial combiner input terminals.

2. The transmission system of claim 1, further comprising:

a broadband booster receive antenna that couples radio frequency energy from a main wireless cable transmitter, said radio frequency energy being in a frequency range of 2.150 GHz to 2.686 GHz; and

a low noise amplifier assembly, comprising at least one low noise amplifier that amplifies the radio frequency energy from said broadband booster receive antenna and provides said radio frequency energy in an electrical current form to said input signal connector.

3. The transmission system of claim 2, further comprising:

a multi-point distribution service transmitter configured to output an MDS signal in a frequency range of 2.150 GHz to 2.162 GHz;

a diplexer configured to accept said MDS signal and said output signal that is output from said radial combiner and provide a composite output signal in a frequency range of 2.150 GHz to 2.686 GHz; and

a transmit antenna connected to said diplexer and transmitting said composite output signal.

4. The transmission system of claim 1, further comprising a driver assembly that amplifies said input signal by a controllable amount so as to provide said input signal to said divider circuit at a specific signal level.

5. The transmission system of claim 4, wherein said driver assembly further comprises a driver processor having a memory configured to hold a set of signal adjustment values, each signal adjustment value corresponding to a different number of power amplifier modules that provide one of said amplified output signals to said radial combiner, said driver assembly adjusting a level of said input signal based on the number of the N power amplifier modules that provide the N amplified output signals.

6. The transmission system of claim 4, further comprising:

an output power sample port configured to sample a power level of said output signal and produce a corresponding feed-back signal; and

a control mechanism configured to adjust a power level of said input signal in response to receiving said feed-back signal.

7. The transmission system of claim 6, wherein:

said output power sample port being configured to sample a forward power and a reflected power of said output signal; and

said control mechanism being configured to identify a fault condition by determining when said reflected power exceeds a predetermined amount.

8. The transmission system of claim 1, wherein each of said N power amplifier modules comprises:

a power supply module;

a radio frequency amplifier module that draws power from said power supply module, comprising, an amplifier chain that receives at least one of said N divided signals and provides a corresponding one of said N amplified output signals to said radial combiner; and

a controller module comprising a processor that employs a computer program that monitors said power supplied by said power supply module and adjusts an output level of said corresponding one of N amplified output signals based on said power supplied.

9. The transmission system of claim 8, wherein said control module of said N power amplifier modules is configured to terminate a transmit mode of operation of said amplifier chain to a standby state of operation so that said specific one of said power amplifier module can be removed from said transmitter without damaging said transmitter while others of the N power amplifier modules remain in said transmit mode of operation.

10. The transmission system of claim 9, wherein said subset of power amplifier modules are configured to receive said interlock signal from at least one of a control panel on respective of said first subset of power amplifier modules, said controller, and a remote terminal.

11. The transmission system of claim 1, wherein:

said modular amplifier further comprising a chassis that holds said N power amplifier modules, said N power amplifier modules being configured to amplify said N divided signals in a frequency range of 2.5 GHz and 2.686 GHz; and

respective of said plurality of N transmission lines being semi-rigid lines and having a length in the range of 21 cm to 30 cm.

12. The transmission system of claim 11, wherein:

said chassis is configured to hold a first subset of said N power amplifiers in an upper portion thereof and a second subset of said N power amplifiers in a lower portion thereof, said second subset of power amplifiers being disposed in chassis in an inverted relationship with respect to said first subset of power amplifiers;

said chassis comprises a front portion through which respective of said N power amplifiers are inserted; and

said radial combiner being disposed behind said rear portion of said chassis.

13. The transmission system of claim 1, further comprising:

a personal communications service receive antenna that couples radio frequency energy from a PCS subscriber terminal, said radio frequency energy being in a frequency range of 1.85 GHz to 1.909 GHz;

a low noise amplifier assembly that amplifies the radio frequency energy from said personal communications service receive antenna;

a receiver that receives said radio frequency energy from said low noise amplifier assembly and produces a received baseband signal;

a message processor that performs message processing functions on said received baseband signal and produces an output baseband signal; and

a transmitter that applies said output baseband signal to said modular amplifier.

14. The transmission system of claim 1, further comprising an up-conversion circuit configured to receive said input signal as a baseband signal and upconvert said input signal to within a frequency range of 2.5 GHz and 2.686 GHz, said input signal comprising at least M channels, where M is an integer greater than or equal to one.

15. The transmission system of claim 1, further comprising a R×

N selection circuit configured to select R channels from said input signal and output said R channels as N outputs, when R is greater than N, said selection circuit combining at least two of said R channels into one of said N outputs, said selection circuit being controllably configured to divide at least one of said R channels so as to a produce a plurality of said N outputs, said selection circuit applying said N outputs to said N power amplifier modules.

16. The transmission system of claim 1, wherein said input signal connector is configured to connect to a head-end transmitter and receive a single channel therefrom, said single channel being applied to said modular amplifier as said input signal.

17. The transmission system of claim 1, wherein:

said divider is configured to divide an input signal into more than N divided signals;

said N power amplifier modules being configured to operate with additional power amplifiers; and

said plurality of N transmission lines being configured to operate with additional transmission lines so that said power level of said output signal increases when said input signal is divided into greater than N divided signals, amplified by more than N power amplifiers, and combined via said radial combiner which is configured to combine more than N signals applied thereto.

18. The system of claim 1, wherein:

said modular amplifier being configured for use in a PCS base station.

19. The system of claim 1, wherein:

said modular amplifier being configured to be hosted in a general purpose reconfigurable transmitter.

20. The system of claim 19, wherein:

said general purpose reconfigurable transmitter being a wireless alternative to a wired telephone service.

21. The system of claim 20, wherein said amplifier being configured to operate in a personal access communication system.

22. The system of claim 21, wherein:

said personal access communication system being configured to transmit data.

23. A modular transmission system comprising:

means for receiving an input signal comprising a wireless cable channel;

means for dividing said input signal into a plurality of divided signals;

means for amplifying a first one of said plurality of divided signals by a predetermined amount using discrete amplifiers so as to produce a first amplified divided signal;

means for separately amplifying a remaining portion of said plurality of divided signals by a predetermined amount so as to produce a plurality of amplified divided signals;

means for combining said first amplified divided signal with said plurality of amplified divided signals and outputting a composite amplified output signal at a predetermined power level;

means for determining a number of amplified divided signals combined by said means for combining;

means for monitoring a level of said amplified output signal; and

means for adjusting a level of said amplified output signal based on the number of amplified divided signals determined by said means for determining.

24. The transmission system of claim 23, further comprising storage means for storing a set of adjustment values, each adjustment value corresponding to said number of amplified divided signals, wherein,

said means for adjusting a level of said amplified output level for adjusting a level of said input signal by one of said adjustment values that corresponds with said number of amplified divided signals.

25. The transmission system of claim 23, further comprising means for removing said first means for amplifying while said means for separately amplifying remains in a transmit state of operation.

26. The transmission system of claim 25, further comprising interlock means for preventing removal of said first means for amplifying until a drain voltage is removed from said discrete amplifiers contained therein and a gate-to-source voltage is adjusted so as to pinch-off respective channels in said discrete amplifiers.

27. The transmission system of claim 23, further comprising means for upconverting said input signal to within a range of 2.5 GHz and 2.686 GHz.

28. The transmission system of claim 23, further comprising means for selecting R channels and outputting said R channels as said plurality of divided signals.

29. A method for amplifying a signal comprising the steps of:

receiving an input signal comprising a wireless cable channel;

dividing said input signal into a plurality of divided signals;

amplifying a first one of said plurality of divided signals by a predetermined amount using discrete amplifiers and producing a first amplified divided signal;

amplifying separately a remaining portion of said plurality of divided signals by a predetermined amount and producing a plurality of amplified divided signals;

combining said first amplified divided signal with said plurality of amplified divided signals and outputting a composite amplified output signal at a predetermined power level;

determining a number of amplified divided signals combined in said combining step;

monitoring a level of said amplified output signal; and

adjusting a level of said amplified output signal based on the number of amplified divided signals determined in said determining step.

30. The method of claim 29, further comprising the step of storing a set of adjustment values, each corresponding to a different value of said number of amplified divided signals, wherein,

said step of adjusting a level of said amplified output level comprises adjusting a level of said input signal by one of said adjustment values that corresponds with said number of amplified divided signals.

31. The method of claim 29, further comprising the step of removing an amplifier module that amplifies said first one of said plurality of divided signals while other amplifier modules continue to separately amplify a remaining portion of said plurality of divided signals.

32. The method of claim 29, further comprising the step of upconverting said input signal to within a range of 2.5 GHz and 2.686 GHz.

33. The method of claim 29, further comprising the steps of selecting R channels from said input signal and outputting said R channels as said plurality of divided signals.

34. A radio frequency transmitter network comprising:

a first transmitter configured to transmit a radio frequency signal to a first subscriber receiver located in a first coverage area; and

a second transmitter configured to transmit said radio frequency signal to another subscriber located in a second coverage area, said first transmitter and said second transmitter each comprising,

an input signal connector configured to connect to a signal source and receive an input signal therefrom,

a modular amplifier comprising,

a divider circuit that divides said input signal into a plurality of divided signals, and

N power amplifier modules, each configured to receive and amplify at least one of said divided signals and to provide a corresponding amplified output signal, N being an integer greater than or equal to two,

a plurality of transmission lines, each having a first end coupled to a corresponding one of said N power amplifier modules and configured to couple respective amplified output signals therefrom, said plurality of transmission lines each having a second end,

a radial combiner comprising N radial combiner input terminals coupled to respective of said second ends of said transmission lines, said radial combiner having an output connector through which an output signal is output at a predetermined output power level, and

a controller connected to said amplifier and configured to adjust a power level of said input signal so as to produce said predetermined output power level of said output signal based on the number of the amplified output signals applied to said N radial combiner input terminals, said controller having an external interface configured to receive and transmit network messages therethrough.

35. The transmitter network of claim 34, further comprising a network controller configured to monitor an operational status of said first transmitter and said second transmitter and dispatch control commands to respective of said first transmitter and said second transmitter.

36. The transmitter network of claim 34, wherein:

said modular amplifier further comprises a chassis that holds said N power amplifier modules, said N power amplifier modules being configured to amplify said N divided signals in a frequency range of 2.5 GHz and 2.686 GHz, and

respective of said plurality of N transmission lines being semi-rigid lines and having a length in the range of 21 cm to 30 cm.

37. The transmission network of claim 34, wherein:

said network controller being configured to produce and send a power set message to said first transmitter, said power set message comprising a parameter indicative of another predetermined output power level of said output signal to be produced by said first transmitter; and

said controller of said first transmitter being configured to respond to said power set message by changing a number of power amplifier modules providing said amplified output signals to the radial combiner based on said another predetermined output power level indicated in said power set message.

38. The transmission system of claim 34, wherein said controller is configured to send a message indicating how many of said N power amplifier modules are presently operating in a transmit mode of operation.

39. The transmission system of claim 38, wherein:

said network controller is configured to send a network message query to at least one of said first and second transmitters requesting a response regarding how many of said N power amplifier modules are operating in said transmit mode of operation; and

at least one of said first and second transmitters configured to respond to said network message query with status data corresponding to a present status of said at least one of said N power amplifier modules identified in said network message query.

40. The transmission system of claim 37, wherein said controller comprises a memory and a processor, said processor being configured to manage a management information base that is kept in said memory, wherein said network messages comprise a GET message, a SET message, and a TRAP message consistent with a Simple Network Management Protocol messaging convention.

41. The transmitter network of claim 34, further comprising a main transmitter that transmits a plurality of wireless cable channels, wherein:

said first and second transmitter each further comprise an antenna coupled to a low noise amplifier assembly for receiving said plurality of wireless cable channels and providing an amplified signal to said input signal connector as said input signal, said low noise amplifier assembly comprising at least two low noise amplifiers and a control mechanism, said control mechanism configured to select one of said at least two low noise amplifiers to amplify said input signal.

42. The transmitter network of claim 34, wherein:

said first transmitter is configured as a wireless cable main transmitter and further comprises a transmit antenna configured to transmit said output signal to said first coverage area; and

said second transmitter is configured as broadband booster and further comprises another transmit antenna, wherein a portion of said second coverage area being located in an area not covered by said first coverage area.

43. A radio frequency transmitter network comprising:

first transmitter means for transmitting a radio frequency signal to a first subscriber receiver located in a first coverage area; and

second transmitter means for transmitting said radio frequency signal to another subscriber located in a second coverage area, said first transmitter and said second transmitter each comprising,

means for receiving said radio frequency signal as an input signal comprising a wireless cable channel,

means for dividing said input signal into a plurality of divided signals,

means for amplifying a first one of said plurality of divided signals by a predetermined amount using discrete amplifiers so as to produce a first amplified divided signal,

means for separately amplifying a remaining portion of said plurality of divided signals by a predetermined amount so as to produce a plurality of amplified divided signals,

means for combining said first amplified divided signal with said plurality of amplified divided signals and outputting a composite amplified output signal at a predetermined power level,

means for determining a number of amplified divided signals combined by said means for combining;

means for monitoring a level of said amplified output signal, and

means for adjusting a level of said amplified output signal based on the number of amplified divided signals determined by said means for determining.

44. The transmission network of claim 43, further comprising means for remotely controlling said predetermined output power level of said first transmitter and said second transmitter.

45. The transmission network of claim 44, wherein said means for remotely controlling comprises:

means for sending a GET status message to said first transmitter means;

means for compiling a response message, comprising means for retrieving status data about said first transmitter means from a management information base held in said first transmitter means;

means for determining whether a reduction in a number of power amplifiers employed in said first transmitter means will degrade said first coverage area below a predetermined area;

means for determining whether an increase in a number of power amplifiers in said second transmitter means will compensate for a degradation in said first coverage area; and

means for increasing an output power level of said output signal from said second transmitter means.

46. A method for transmitting a radio frequency signal in a network comprising:

receiving a radio frequency signal as an input signal comprising a wireless cable channel;

dividing said input signal into a plurality of divided signals;

amplifying a first one of said plurality of divided signals by a predetermined amount using discrete amplifiers and producing a first amplified divided signal;

amplifying separately a remaining portion of said plurality of divided signals by a predetermined amount so as to produce a plurality of amplified divided signals;

combining said first amplified divided signal with said plurality of amplified divided signals and outputting a composite amplified output signal at a predetermined power level;

determining a number of amplified divided signals combined in said combining step;

monitoring a level of said amplified output signal, and

adjusting a level of said amplified output signal based on the number of amplified divided signals determined in said determining step;

transmitting said amplified output signal to a first coverage area; and

transmitting another amplified output signal to a second coverage area.

47. The method of claim 46, further comprising the step of controlling remotely a predetermined output power level of said amplified output signal and said another amplified output signal.

48. The transmission network of claim 47, wherein said step of controlling remotely comprises:

sending a GET status message to a first transmitter that transmits said amplified output signal;

compiling a response message, comprising retrieving status data about said first transmitter from a management information base held in said first transmitter means;

determining whether a reduction in a number of power amplifiers employed in said first transmitter will degrade said first coverage area below a predetermined area;

determining whether an increase in a number of power amplifiers in a second transmitter that transmits said another amplified output signal will compensate for a degradation in said first coverage area; and

increasing an output power level of said another amplified output signal.