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US2219751A - Single side band diversity radio receiving system - Google Patents

Single side band diversity radio receiving system Download PDF

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Publication number
US2219751A
US2219751A US291481A US29148139A US2219751A US 2219751 A US2219751 A US 2219751A US 291481 A US291481 A US 291481A US 29148139 A US29148139 A US 29148139A US 2219751 A US2219751 A US 2219751A
Authority
US
United States
Prior art keywords
signal
carrier
branch
amplitude
detector
Prior art date
Legal status (The legal status 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 status listed.)
Expired - Lifetime
Application number
US291481A
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English (en)
Inventor
Frank A Polkinghorn
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
AT&T Corp
Original Assignee
Bell Telephone Laboratories 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
Priority to BE479917D priority Critical patent/BE479917A/xx
Application filed by Bell Telephone Laboratories Inc filed Critical Bell Telephone Laboratories Inc
Priority to US291481A priority patent/US2219751A/en
Priority to US292777A priority patent/US2219749A/en
Priority to GB10998/40A priority patent/GB539655A/en
Priority to FR867359D priority patent/FR867359A/fr
Application granted granted Critical
Publication of US2219751A publication Critical patent/US2219751A/en
Priority to CH270712D priority patent/CH270712A/de
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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Classifications

    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04BTRANSMISSION
    • H04B7/00Radio transmission systems, i.e. using radiation field
    • H04B7/02Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas
    • H04B7/04Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas
    • H04B7/08Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the receiving station
    • H04B7/0837Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the receiving station using pre-detection combining
    • H04B7/0842Weighted combining
    • H04B7/0848Joint weighting
    • H04B7/0857Joint weighting using maximum ratio combining techniques, e.g. signal-to- interference ratio [SIR], received signal strenght indication [RSS]
    • HELECTRICITY
    • H04ELECTRIC COMMUNICATION TECHNIQUE
    • H04BTRANSMISSION
    • H04B1/00Details 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
    • H04B1/06Receivers
    • H04B1/16Circuits
    • H04B1/30Circuits for homodyne or synchrodyne receivers
    • H04B1/302Circuits for homodyne or synchrodyne receivers for single sideband receivers

Definitions

  • This invention relates to radio communication systems, and more particularly to methods and means for reducing fading effects and maintaining a favorable signal-to-noise ratio in a diversity reception system.
  • the same transmitted signal is simultaneously received from the signal source at the transmitting station over a plurality of paths through space.
  • the amplitude of received signal over the various paths usually varies as between the different paths with changes in the condition of the space transmission medium, so that as the amplitude of the signal received over one path increases, that over another or other of the paths may diminish. These amplitude variations are generally at random and are continually taking place.
  • the carrier upon Which the side bands are based is usually transmitted with the side bands at sufficient amplitude to provide for the proper demodulaticn of the side bands in the nal detector at the receiving station.
  • the carrier fades With the side bands; and as the noise introduced at the receiving station input of the fading path yields in the receiving apparatus an audible component by interaction With the unmodulated carrier frequency Wave component as does a modulation of the carrier frequency, the same fading of the carrier and its side bands which reduces the signal amplitude also reduces the noise amplitude.
  • this effect is overcome bythe employment of a method' and means for causing the amplitude of the demodulated signal and accompanying '40 noise contributed byl each kof the diversity branches of the receiving system to vary With the amplitude, and under the control, vof a selected portion of the energy freceived from the u transmitting station over the corresponding space 45 path.
  • the signal and selected controlling portion which may for example bethe accompanying carrier or an accompanying pilot frequency
  • the amplitude of the demodulating frequency locally supplied to the corresponding diversity branch islikewise diminished; and as both the signal output andthenoise output of the branch depend upon the amplitude of the locally supplied carrier or demodulating frequency, the demodulation being non-linear in character, the noise output is diminished with the signal output. Therefore, a favorable over-all signal-to-noise ratio in the signal receiver is maintained at the receiving station.
  • the radio receiving apparatus-with Vthe different space paths is represented as being yby vvay of the antennas AI and A2, which may be of any suitable type. These antennas feed over radio-recaption-branches I and 2, respectively, .to the common signal.receiver I0. Only 'two antennas with their associated radio receiversare shown, but it lWill .b e understoodthat any greater number,
  • each radio reception. branch is of identically the same type as thoseincluded inthe other branch; and corresponding elements aredesignated by the same reference numbers, excepting that a prime is affixed -to the designating numerals of the second branch.
  • the description of the arrangement and operation-of. the elements in one branch may therefore be understood to apply to the operation and arrangement of the elements in the other branch.
  • the energy-received by the antenna passes to high frequency amplifier and first detector elements II.- In the first detector the received enffergy is modulated by a ⁇ high frequency Wave sup- .pIiedQby-t'he fbeat oscillator ⁇ 2i) and the desired products of ⁇ modulation are-amplified in a twostage intermediate-frequency amplifier I2.
  • the above-mentioned elements may be regarded as constituting the radiorreceiver of the reception branch
  • Thel intermediate frequency amplifier 5I2- operates into .a'branched circuit, one branch of which includes anV isolation amplifier I3 and a non-linear second detector I4, which may be of the ordinary square-jaw type and the other ybranch of which selects a narrow frequency-band including the carrier that passes through the bandpass crystal filterll5.
  • the carrier output from the filter vI5 is supplied through the transformer 28 to the grid circuits of the triode detectors I6 and I1 in parallel.
  • These detectors operate'to rectify the carrier oscillations supplied thereto and produce direct current potentials proportional tothe amplitude of such carrier os- "cillationsl
  • 'I'his local carrier is ampliiied in the local carrier amplifier I8 and supplied throughthe transformer 29 to the plate circuit ofthe detector I4.
  • the degree of amplificationof the carrier is controlled by the potential across ⁇ the resistance I9 included in the output circuit .of the detector I6, this potential being appliedl in opposition to the normal biasing potential from the battery 22 in the input circuit of the amplifier I8, as indicated by the polarity markings onresistance I9 and battery 22.
  • the carrier oscillations ⁇ supplied to the detector M of branch to a common sig'-l 2 are similarly controlled by the amplifier I 8' and its associated circuits.
  • the signal frequencies which result from the demodulation that occurs in the second detector I4 of branch I are inductively communicated by Way of transformers 2
  • variable control-potential is determined by the combined strength of the carrier Waves received in the two branches I and 2 as the input of the detectors II yand I'I' is ,connected to the respective carrier lilters I 5 and I5 as described above.
  • the distant station is transmitting a radio frequency carrier of relatively small amplitude, and a single side band resulting from the modulation of the carrier frequency with the signal frequency.
  • the radio receiver elements II and II of the two radio reception branches I and 2 are tuned to select the carrier and its side band, and the beatfoscillator 20 is so adjusted as to produce, by modulation with the incoming wave,
  • an intermediate frequency Wave of the desired frequency for instance, 400 kilocycles.
  • a portion .of this amplified intermediate frequency passes into the branch circuit in.. cluding the band-pass crystal filter I5.
  • This lfilter' may be designed to pass a frequency band Vtransmitting station and in the beat oscillator 20 at the receiving station.
  • the band passed by the filter I5 may be 200 ⁇ cycles wide, or narrower to the extent that the oscillavtor stability and rate of change of carrier or pilot frequency permits.
  • the narrow band including the carrier at its intermediate frequency value passes to the input .circuits of detectors I6 and II.
  • the 'I'he tube of the local carrier amplifier I 8 is preferably ofthe variable mu type.
  • the bias in the input circuit of this tube is determined by the potential of the biasing battery 22 and the potential drop across the resistance I9. This bias is so adjusted that with no carrier input to detector .I6, amplifier I8 gives very little local carrier output to secondV detector I4. With a normal carrier input ⁇ to detector I6 the increased potential across resistance I9, in opposition to the potential of biasing battery-22,'decre'ases the negative bias in the input circuit of amplifier I8 'to-produce normal gain in the local carrier frequency supplied to second detector I4.
  • the amplitude of the signal contributed bythe non-linear second detector of each receiving branch of the system is automatically varied with the variation of the radio frequency input to the corresponding branch, and when the signal contribution of any of the branches is diminished by fading', the noise contribution of that branch is diminished with it.
  • the amplifier I3 in the signal subbranch of each of the branches I and 2 is of the screen grid type for preventing the local carrier oscillations which are fed into the plate circuit of the second detector I4 by the amplier I8 from feeding back through the channel and appearing in the other detector circuits.
  • detector I6 of branch I operates to reduce the negative bias in the input circuit of amplifier I8 to permit a proportionately greater local carrier input to the output circuit of secondk detector I4 ⁇ of branch I; while detector I6 of branch 2, responding to-the diminishing energy input received from antenna A2, reduces the opposing biasydeveloped in resistance I9', thus increasing the negative bias in the input circuit of amplifier I8 to diminish the output of local carrier to second detector I4 in accordance with the reduction in radio frequency energy received over the corresponding branch.
  • the signal received in the common signal receiver I0 is principally that received over the path of the diversity system which has the most favorable signal-to-noiseratio, while the noise that would. otherwise enter the common receiver over the path or paths of reduced'signal energy is diminished by the device which reduces the gain of the transmission path in accordance with the reduction in the received radio frequency energy.
  • the signal volume delivered to signal receiver I0 is held substantially constant.
  • the filtered carrier received from the transmitting ⁇ station may be reconditioned and then used for obtaining automatic frequency control of the beating oscillator k2l! and synchronization of the local carrier oscillator'3Il.
  • the filtered carrier after being reconditioned and amplified may constitute the source of locally applied carrier oscillations in place of the local carrier oscillator 30.
  • the reconditioned carrier is supplied for demodulation' atsubstantially constant amplitude regardless of fading in transmission, and therefore, if applied in the ,l
  • the system in substitution of the carrier oscillations generated locally by oscillator 3G, the system is susceptible of and requires the same automatic amplitude control in accordance with the amplitude of the rectified energy of the branch ⁇ to which it is applied that is utilized in the present invention.
  • ⁇ the invention is also applicable to an angle diversity system -in which 'the same signal is simultaneously received at ydifferent vertical angles by way of a single array of spaced antenna units and is demodulated at each angle by reconditioned carrier arriving at that angle, or by locally generated carrier synchronized the received carrier of the corresponding path.
  • v 1. In a diversity radio receiving system, a plurality of radio receivers each arranged to receive radio; signals arriving from the same signal source L by different paths, a detector and signal frequency amplifier system for each receiver, a signal circuit responsive to the combined signal outputs of said systems, means for selecting and rectifying a portion of the energy received from the transmitting station by each receiver; means for combining the rectified currents, means for controlling the amplification of all the receivers in accordance with the combined rectiied currents so that the inputs to the respective detectors have the same relative signal strengths as the inputs to the receivers, means for supplying .carrier energy to the detector and signal frequency amplier systems, and means ⁇ individual to said receivers and responsive to the individual lrectified Qurrents for so controlling the conversion gain of the individual detector and signal frequency amplifier systems as to'rnaintain the individual signal outputs .of said receivers proportional to the inrality'of radio receivers, each arranged to receive signals arriving from the same signal'source
  • a diversity radio receiving system comprising a plurality of radio reception branches each connected with a common signal receiver and each including a signal detector, means operatively coupled to each branch for selecting and rectifying the signal carrier, means responsive to the rectified carrier current of at least one o'f the branches for similarly controlling the amplication of all of the branches so that the inputs to the respective detectors have the same relative signal strengths as thev signal strengths at the respective branch inputs, ⁇ a source oi' substantially constant amplitude carrier oscillations at the receiving station, means for supplying carrier oscil- I lations from said source to the detectors of'the various branches, and meansresponsiveto the amplitude of the rectified carrier current of each individual branch for-.controlling the' amplitude of carrier oscillations supplied from said source to the detector of the corresponding branch.
  • -a diversity radio receiving system comprising a plurality of radio reception branches each connected With a common signal receiver and each including a signal detector, means operatively coupled to each branch for'selecting zand rectifying the signal carrier, means for combining the rectied carrier current of all the branches tosmilarly control the'amplii-lcation of all of the branches so that the 'inputs to the respective detectors have the same relative signal strengths as the signal strengthsat the respective branch inputs, a source of substantially constant amplitude carrier oscillations, means for supplying carrier, oscillations from said source to the detectors of the various branches, ⁇ and ⁇ means responsive to the amplitude 'of the rectified carrier current of each individual branch for controlling the amplitude of the output supplied to the common signal receiver by the detector of the corresponding branch.
  • a single side band diversity radio receiving system comprising a plurality of radio reception branches connected with 'a common signal receiver and each including a signal. detector, means operatively coupled to each branch for selecting and rectiiying a portion of the energy received from the transmitting stationby way of the corresponding branch, a source of substantially constant amplitude Acarrier oscillations, variable transmission means for supplying oscillations from said source to the detectors of the various branches, and means responsive to the rectified energy of each branchfor controlling said transmission means to regulate the amplitude of oscillations applied to eachdetector from said .sourceinaccordance with' the amplitude of said rectified energy-of the corresponding branch.
  • a diversityl radio receiving system comprising a 4plurality of radio reception branches connected with a common signal receiver and -eachV including a signal detector, means operatively coupled to each branch for selecting and rectifying a portion of the energy received from the transmitting station by Way of the corresponding-branch, means for combining the rectifiedxenergy. derived from all of the branches, means responsive to said combined rectified energy for similarly controlling the amplification of all of the branches so that the inputs to the respective detectors have the same relative signal strengths as the signalsat the corresponding branchY inputs, and means responsive to the rectied-energyof each branch for controlling the amplitude of the detected signal output of the corresponding branch in accordance with the amplitude of said rectified energy of the corresponding branch.
  • a single side band diversity radio receiving system comprising a plurality of radio reception branches connected Witha common signal receiver and each including a signal detector, means operatively coupled to each branch for selecting and rectifying a portion ofthe energy received from the transmitting Vstation-by way of the corresponding branch, means responsive to the rected energy derived from at least one of the branches for similarly controlling the amplication of all of the branches so that the inputs to the respective detectors have the same relative signal strengths as the signals at the corresponding branch inputs, a source of substantially constant amplitude carrieroscillations, means for supplying oscillations from said source to the detectors ofv the various branches, and means responsive to the rectied energy ofY each branch for controlling the amplitude ofthe signal output of the corresponding branch in accordance with the amplitude of the said rectiiied energy of the corresponding branch.
  • the method of maintaining a favorable signal-to-noise ratio in a diversity radio receiving system utilizing means for receiving in different radio reception branches the radio signals arriving from the same signal source over dverent space paths, applying equal amplification to the energy received in each branch, separately selectingand rectifying a portion of the energy received over each branch, and separately demodulating the signal energy component of each branch by carrier oscillations supplied from a substantially constant ,amplitude local source, which consists in utilizing the rectied portion of the energy of each branch to control in accordance with its own amplitude the amplitude of the demodulated signal component of the corresponding branch, and combining and utilizing the demodulated signal components of all the branches.
  • the method of maintaining a favorable sig- ⁇ nal-to-noise ratio in a diversity radio receiving system having a plurality of -radio reception branches connected with a common signal receiver and arranged to receive radio signals arriving from the same signal source over diiierent paths, which consists in utilizing the combined carrier energy received over the diierent branches for similarly controlling the radio frequency amplication of all of the branches, and utilizing the carrier energy received over each individual branch for controlling in accordance with its amplitude the amplitude of the signal contribution of the corresponding branch to the common signal receiver.

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  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Radio Transmission System (AREA)
US291481A 1939-08-23 1939-08-23 Single side band diversity radio receiving system Expired - Lifetime US2219751A (en)

Priority Applications (6)

Application Number Priority Date Filing Date Title
BE479917D BE479917A (fr) 1939-08-23
US291481A US2219751A (en) 1939-08-23 1939-08-23 Single side band diversity radio receiving system
US292777A US2219749A (en) 1939-08-23 1939-08-31 Single side band diversity radio receiving system
GB10998/40A GB539655A (en) 1939-08-23 1940-06-28 Improvements in diversity radio communication systems
FR867359D FR867359A (fr) 1939-08-23 1940-10-02 Systèmes de communications radioélectriques
CH270712D CH270712A (de) 1939-08-23 1948-01-09 Mehrfachradioempfangsanlage.

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US291481A US2219751A (en) 1939-08-23 1939-08-23 Single side band diversity radio receiving system

Publications (1)

Publication Number Publication Date
US2219751A true US2219751A (en) 1940-10-29

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Family Applications (1)

Application Number Title Priority Date Filing Date
US291481A Expired - Lifetime US2219751A (en) 1939-08-23 1939-08-23 Single side band diversity radio receiving system

Country Status (5)

Country Link
US (1) US2219751A (fr)
BE (1) BE479917A (fr)
CH (1) CH270712A (fr)
FR (1) FR867359A (fr)
GB (1) GB539655A (fr)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2555557A (en) * 1947-02-25 1951-06-05 Rca Corp Diversity receiver
US2720583A (en) * 1950-12-06 1955-10-11 Murray G Crosby Diversity receiving system
WO1981000495A1 (fr) * 1979-08-13 1981-02-19 Western Electric Co Recepteur a une seule bande laterale avec correction d'avance avant basee sur des signaux de commande pour la distorsion induite par mouvement
US5222250A (en) * 1992-04-03 1993-06-22 Cleveland John F Single sideband radio signal processing system

Cited By (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2555557A (en) * 1947-02-25 1951-06-05 Rca Corp Diversity receiver
US2720583A (en) * 1950-12-06 1955-10-11 Murray G Crosby Diversity receiving system
WO1981000495A1 (fr) * 1979-08-13 1981-02-19 Western Electric Co Recepteur a une seule bande laterale avec correction d'avance avant basee sur des signaux de commande pour la distorsion induite par mouvement
US4313211A (en) * 1979-08-13 1982-01-26 Bell Telephone Laboratories, Incorporated Single sideband receiver with pilot-based feed forward correction for motion-induced distortion
US5222250A (en) * 1992-04-03 1993-06-22 Cleveland John F Single sideband radio signal processing system

Also Published As

Publication number Publication date
GB539655A (en) 1941-09-18
FR867359A (fr) 1941-10-20
CH270712A (de) 1950-09-15
BE479917A (fr)

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