US2089568A - Diversity receiver - Google Patents

Diversity receiver Download PDF

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Publication number
US2089568A
US2089568A US64801A US6480136A US2089568A US 2089568 A US2089568 A US 2089568A US 64801 A US64801 A US 64801A US 6480136 A US6480136 A US 6480136A US 2089568 A US2089568 A US 2089568A
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Prior art keywords
diversity
signal
fed
output
radio frequency
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Expired - Lifetime
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US64801A
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English (en)
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John B Moore
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RCA Corp
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RCA Corp
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Priority to BE420094D priority Critical patent/BE420094A/xx
Application filed by RCA Corp filed Critical RCA Corp
Priority to US64801A priority patent/US2089568A/en
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    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B7/00—Radio transmission systems, i.e. using radiation field
    • H04B7/02—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas
    • H04B7/04—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas
    • H04B7/08—Diversity systems; Multi-antenna system, i.e. transmission or reception using multiple antennas using two or more spaced independent antennas at the receiving station
    • H04B7/0837—Diversity 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

Definitions

  • My present invention relates to the general improvement of diversity radio receivers.
  • Diversity receivers have proven especially successlul for the reduction of fadingan undesirable phenomenon experienced during the reception of signals transmitted on short radio waves. These receivers usually make use of a multiplicity of separated antennae whose currents either before or after rectification are combined to operate a single translating device. However, diversity arrangements as heretofore known are, as far as I am aware, limited in flexibility.
  • the prime object of my present invention is to provide va highly flexible diversity receiving system which may be used for telegraphic or telephonic signals, or which may be used to provide separate signals of the telephonic or telegraphic type or which may be used to provide, simultaneously, separate signals some of Which result from partial employment of full diversity receiving apparatus.
  • FIGS. 1 to 4 are block diagrams generally illustrative of my present invention
  • FIG. 5 schematically illustrates in somewhat greater detail the radio frequency and intermediate frequency units of Figures 1 to 4 inelusive
  • Figure 6 illustrates the signal control circuits of my present invention which are utilized in a manner to be described more fully hereinafter;
  • Figure '7 is a Wiring diagram of an audio frequency amplifier which may be used in connection with my present invention.
  • Figure 8 is a wiring diagram of a tone keying system useful in connection with my present invention.
  • Figure 9 illustrates a monitoring arrangement which may be used in my present diversity receiving system.
  • the three receivers may be utilizedz-to supply three separate telephone signals; to provide a diversity arrangement of three receivers; to supply a single telephonic signal or a single telegraphic signal; or to connect two receivers on either type of service, making the third receiver available for another signal.
  • three separate and diiferent telegraphic signals may be received.
  • FIG 1 shows the general rack layout of the apparatus utilized in my improved diversity receiving system.
  • the radio frequency apparatus RF for each receiver is placed on top.
  • the radio frequency apparatus of each receiver is provided with separate tubes and circuits for each of three distinct frequency bands, the antenna transmission line plugs for which are indicated at Pl-i, i2, Pi-3, P2l, P2-2, P2-3, P3-l, P3--2 and P33.
  • Beneath the radio frequency stages RF-i are placed, as indicated, the power control apparatus PC, audio frequency amplifier AF -l intermediate frequency apparatus IFi and diode detection apparatus DD-l.
  • the apparatus beneath the radio frequency stages RF2 is quite similar with the exception of the provision of signal control apparatus SC which shall be described in greater detail hereinafter.
  • Beneath the radio frequency stages RF3 are mounted two tone keyers and oscillators TKO-l and TKO-Z. If desired, either of these tone keyers and oscillators may be replaced by an audio frequency amplifier such as AFI and AF-2.
  • AFI audio frequency amplifier
  • AF-2 audio frequency amplifier
  • Various input, automatic gain control, and monitoring output circuits are provided, as indicated, and will be described in greater detail hereinafter.
  • FIGs 2, 3, and 4 diagrammatically illustrate some of the combinations obtainable with my improved diversity receiving apparatus, by manipulation of the switches on the signal control panel SC of Figure 1.
  • FIG 2 the three receivers are shown connected in full diversity fashion for either telephony or telegraphy.
  • two of the receivers are combined to give diversity telephony or telegraphy reception and the other receiver is left free for either telegraphy or telephony; and in Figure 4, the three receivers are arranged so as to produce three separate signals.
  • FIG. 5 shows in greater detail, although in block diagram form, the apparatus contained within the radio frequency units and intermediate frequency units of Figure l.
  • the antenna plugs Pll, PI2 and Pl3 may be connected to antennae separately suited for different radio frequency bands such as, respectively, three to six megacycles, six to twelve megacycles and twelve to twenty-four megacycles. These bands are chosen simply by way of illustration and are not to be considered in any way as limiting the present invention.
  • the output of block Pll is fed successively through the antenna tuning stage ATL-I and radio frequency tuning stages RFTi i and RFTI2. These stages are pro- Vided with as many tubes, tuning circuits and individual controls or, if desired, unicontrolled controls as found desirable.
  • the output of the radio frequency tuning stage RFTi2 is fed to the tube detector stage TDi--l which is also supplied with oscillations from the local oscillator LO!I. All of this apparatus, including independent tubes in the amplifier, detector and oscillator stages are duplicated beneath the plugs Pl'2 and Pl-3 with, of course, suitable adjustments in the circuits to make them suitable for operation on the other frequency bands chosen.
  • the radio frequency filament switch RFS selectively energizes the filaments of all tubes under each plug. With the switch arms in their upper position, all tubes under plug Pi--l will be energized, thereby receiving signals to which the three to six megacycle lband system is tuned.
  • signals may be received on the channel or frequency band to which the circuits under plug Pi 2 are adjusted, etc.
  • -I, TDI-2 and 'IDi3 have their outputs connected in parallel and all channels are beat down by suitable tuning of the local oscillators, LOI-I, LOi2 and LOi-3 to a common intermediate frequency such as three hundred kilocycles.
  • the apparatus of the unit RF! ( Figure 5) is duplicated in the units RFZ and RF3 of Figure 1, all of the outputs of which are beat down, as shown in Figure 5, to, for example, a common intermediate frequency such as three hundred kilocycles.
  • Intermediate frequency energy is fed separately, as shown in Figure 5, to the intermediate frequency units IFE, IF2 and IF3 which are identical in structure. Consequently, only unit IFI will be described in detail.
  • the output of the intermediate frequency detector IFD-I is adjusted to some suitable value such as fifty kilocycles and fed through the intermediate frequency transformer IFTi to two intermediate frequency amplifier units NFAI and WFA-l.
  • Each of these fifty kilocycle amplifiers NFA-l and WFAE are suitably tuned and are provided with a suitable number of tubes to provide for desired amplification of the waves supplied thereto.
  • These amplifier stages differ in that amplifier NFA! passes a narrower band of frequencies and is adapted for telegraphy as it tends to reduce noise level and eliminate interference from: adjacent channels, whereas intermediate frequency amplifier WFA-I has a broader frequency characteris-, tic and is particularly suited for telephony since it will tend to cause reproduction of the transmitted signal with high fidelity.
  • connection X, Y, Z of Figure 5 are brought to the signal control panel SC of Figure l which is illustrated in greater detail in Figure 6.
  • tector outputs of DDl, DD--2 and DD3 are connected respectively to the signal indicators or milliammeters MAI, MA-Z and MA3.
  • the output conductor 2 of indicator MAI is connected to the switches !A and EB; the output conductor 4 of signal indicator MA-2 is connected as indicated to the switches 2A and 2B,
  • switches EB, 23 and 3B are thrown to their down As shown in Figure 6, the diode deposition so that the following contacts are closed:
  • contacts 4B! and 432 are closed. Normally, contacts tBNl and liBNZ are closed.
  • Automatic gain control supply voltage for the radio frequency units RFI, RF2 and RF3 is brought in from conductor ID and is fed back to the radio frequency units through conductors i2, 14 and [6 which lead to the grids of the radio frequency amplifier stages.
  • switches TCS and condensers TC are provided.
  • switches IA, 2A and 3A are thrown to the up position so that the following contacts are closed: lAi, EAZ, 2Al, 2A2, SAi and 3A2, the switch iA being moved so that contacts 4A! and 5A2 are closed or in their normal position.
  • the contacts 5A3, 4A4 are closed, as a consequence of which the combined output is made manifest in the signal indicator or milliammeter M t-.
  • the combined telephony signal will appear in conductor 26 and this is fed to a common audio frequency amplifier such as AF- I or AF2 of Figure 1, which will be described in greater detail hereinafter.
  • the automatic gain control with the full diversity telephony connection is obtained from conductor 22 which, it will be found, is connected to the automatic gain control leads l2, M and i6 leading to the radio frequency tubes of the radio frequency units RFl, RFZ and RF3 of Figure 1.
  • receiver 3 is to supply the telephonic signal and that receivers l and 2 are to be combined in diversity fashion for a telegraphic signal.
  • Contacts SM and 3A2 of switch 3A. are closed and with the understanding that contacts 4M and 4A2 of switch 4A are normally closed, it should be clear that on conductor 28 the audio frequency signal will be impressed upon an audio frequency amplifier such as AFi of Figure 1.
  • the automatic gain control voltage will be returned for receiver 3 through lead 22, contacts SAI, now closed, and thence over conductor 56 to the radio frequency tubes of receiver 3.
  • switch contacts IBI and 132 of switch B3 are closed, as are contacts 223i and 2152 of switch 23.
  • the combined telegraphic signal is then fed out over conductor 8 to a suitable tone keyer such as TKO-2 of Figure 1 and the automatic gain control voltage is brought in over conductor I8 and fed to the radio frequency tubes of receivers I and 2 over conductors l2and l-i.
  • Audio frequency telephonic signal is fed to the two stage resistance coupled amplifier AFRA and thence to a suitable output circuit, as indicated in Figure 7.
  • a suitable output circuit as indicated in Figure 7.
  • the combined outputs of the diode detectors are, of course, fed into terminal 39.
  • the output of the audio frequency resistance coupled amplifier AFRA of Figure 7 may be utilized in a loudspeaker or fed to suitable circuits for radio rebroadcasting.
  • a tone keyer oscillator such as TKOI of Figure 1 is illustrated in greater detail in Figure 8.
  • the contacts 8 and ID may be connected respectively to the leads 8 and Ill of Figure 6.
  • the telegraphic output from i, 2 or 3 of the diode detectors is fed in at the contact 8' and in the presence of a signal current flow through the tube 40 is cut off.
  • the plate lead 42 no longer maintains the grids of tubes 44 at a cut-off value, but
  • a tone source 46 permits oscillations from a tone source 46 to be amplified by the tubes 44 and eventually fed into a transmission line TL.
  • This tone is fed to some distant rectifier, for example, at some central receiving point, and the rectifier 50 operates a suitable recorder 54.
  • current flow through tube 48 will cause such a high negative bias to be impressed upon the grids of tubes 44 that tone from source 46 will not be fed into the transmission line IL.
  • the time control circuit T08 controls the time constant of the voltage fed back through contact ID" of Figure 8 and conductor l6 of Figure 6.
  • tube 60 and its associated circuits are provided.
  • Tube 69 operates in such a way that during the period of no signal, the plate current flow reduces the amplification factor of the radio frequency amplifiers.
  • tube 6! becomes blocked and is rendered useless so that only the rectified signal provides its own automatic gain control voltage over the conductor H3.
  • Figure 9 illustrates a suitable monitoring arrangement for the present diversity system. With the arrangement illustrated in Figure 9 it is possible to monitor the audio frequency amplifiers and the various keying circuits.
  • the monitor switches of Figure 9 are of the same type as the diversity switches of Figure 6. Earphones are connected to the monitor jacks T9, 12 which, in turn, are connected to the monitoring switches Ml, M2, M3, M4.
  • the monitor switches are connected to the outputs of the various units and are not connected in parallel to the diversity switches.
  • the leads marked AFI are connected across the output terminals marked "output of Figure 7.
  • the leads marked keyer are connected to the output terminals, so marked, of Figure 8.
  • the leads marked IF are connected to the output of a detector which is supplied partially with the energy coming from such intermediate frequency amplifiers as NFA--l and WFA-I of Figure 5 and with energy from a local heterodyning oscillator.
  • Such monitoring when using leads marked IF, serves admirably well in check ing the tuning of the radio frequency oscillators, and for aural reception of slow speed telegraphic signals.
  • a rectifier type of volt meter RTV shown in Figure 9, is provided with an on-off switch OOS to indicate the strengths of the various monitored signals. This is used particularly for checking and adjusting the strength of telephone or keyed tone signals supplied to the lines leading to central offices or to broadcast control centers.
  • Receiving apparatus comprising a plurality of antennas, a separate radio frequency amplifying and heterodyning unit connected to each an tenna, rectifiers for separately rectifying the output of each of said units, a plurality of translating devices, and control switches for feeding all of the rectified energy into one of said translating devices and, at will, for separately feeding the rectified energy into different translating devices, or for feeding the rectified outputs of a pair of rectifiers into one translating device and the rectified output of another rectifier into a different translating device.
  • each of said units includes Wide and narrow band circuits, and means to feed the energy derived from the antennas selectively through said circuits.
  • Receiving apparatus comprising a plurality of antennas, a separate radio frequency amplifying unit connected to each antenna, rectifiers for separately rectifying the output of each of said units, a plurality of translating devices and a control switch for feeding all of the rectified energy into one of said translating devices and, at Will, for separately feeding the rectified energy into different translating devices, or for feeding the rectified outputs of a pair of rectifiers into one translating device and the rectified output of another rectifier into a different translating device.
  • each of said units includes Wide and narrow band circuits, and means to feed the energy derived from the antennas selectively through said circuits.
  • Receiving apparatus comprising a plurality of antennas, a separate radio frequency amplifying and heterodyning unit connected to each antenna, rectifiers for separately rectifying the output of each of said units, a plurality of filter units of different band pass characteristics and means operable at will for causing the energy from one or more of said rectifying units to be fed through a selected one of said filter units.
  • Apparatus according to claim 5 having means for feeding to one of said filter units the combined energies derived from different ones of said antennas, While simultaneously feeding to another of said filter units the energy derived solely from still another of said antennas.

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  • Computer Networks & Wireless Communication (AREA)
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US64801A 1936-02-20 1936-02-20 Diversity receiver Expired - Lifetime US2089568A (en)

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US64801A US2089568A (en) 1936-02-20 1936-02-20 Diversity receiver

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Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2474663A (en) * 1944-12-11 1949-06-28 Rca Corp Remote-control system for selectively controlling a plurality of adjustable elements
US2514162A (en) * 1947-04-25 1950-07-04 Rca Corp Diversity reception

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2474663A (en) * 1944-12-11 1949-06-28 Rca Corp Remote-control system for selectively controlling a plurality of adjustable elements
US2514162A (en) * 1947-04-25 1950-07-04 Rca Corp Diversity reception

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