US2151081A - Multiplex receiving system - Google Patents

Multiplex receiving system Download PDF

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Publication number
US2151081A
US2151081A US102286A US10228636A US2151081A US 2151081 A US2151081 A US 2151081A US 102286 A US102286 A US 102286A US 10228636 A US10228636 A US 10228636A US 2151081 A US2151081 A US 2151081A
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United States
Prior art keywords
amplifiers
antenna
transformers
transformer
band
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
US102286A
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English (en)
Inventor
Wendell L Carlson
Vernon D Landon
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RCA Corp
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RCA Corp
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Filing date
Publication date
Priority to BE423746D priority Critical patent/BE423746A/xx
Application filed by RCA Corp filed Critical RCA Corp
Priority to US102286A priority patent/US2151081A/en
Priority to GB25945/37A priority patent/GB504616A/en
Application granted granted Critical
Publication of US2151081A publication Critical patent/US2151081A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

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    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03H—IMPEDANCE NETWORKS, e.g. RESONANT CIRCUITS; RESONATORS
    • H03H7/00—Multiple-port networks comprising only passive electrical elements as network components
    • H03H7/48—Networks for connecting several sources or loads, working on the same frequency or frequency band, to a common load or source
    • H03H7/482—Networks for connecting several sources or loads, working on the same frequency or frequency band, to a common load or source particularly adapted for use in common antenna systems
    • 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
    • H04H20/76—Wired systems
    • H04H20/77—Wired systems using carrier waves

Definitions

  • Our invention relates to a multiplex radio receiving system. More particularly our invention includes in combination a plurality of antennas, band amplifiers, and distributing system for mul- 5 tiplex radio reception.
  • This arrangement requires a high-gain amplifier which has a uniform amplification characteristic over a very broad band of frequencies, if the system is to be used with a plurality of all 20 wave receivers.
  • An amplifier of high gain and uniform amplification is usually subject to cross talk, interference, and hiss when directly coupled to an antenna and to further difiiculties due to the resonant characteristic of the antenna.
  • Another object is to provide a plurality of antennas, each responsive to currents of a band of radio frequencies, and means coupling the antennas to band responsive amplifiers whose output circuits have a common connection to a plu- 45 rality of all wave receivers.
  • a further object is to provide means for attenuating interfering signals which tend to block the amplifiers which couple a plurality of receiving antennas and a plurality of all wave radio receivers.
  • Additional objects are: to obtain highgain from the antenna to the input of the first amplifier to reduce amplifier hiss; to limit cross talk or interference to a narrow band by the use of a plui5 ,rality of band amplifiers; to keep the amplifier tubes within their rated capacity to lessen cross modulation; and to attenuate harmonic output currents by employing narrow band output transformers.
  • FIG. 1 is a schematic circuit diagram of one embodiment of our invention
  • Fig. 2 is a graph showing the frequency characteristics of the radio frequency coupling transformers
  • 10 Fig. 3 is a schematic illustration of one arrangement of a plurality of antennas.
  • Amplifier 1 530 to 900 kilocycles
  • Amplifier 2 900 to 1250 kilocycles
  • Amplifier 3 1250 to 1600 kilocycles
  • the primary of the transformer 5 is a tuned circuit, which is comprised of a capacitor '1 and an inductor 9. Within the inductor winding 'is an adjustable magnetite core II.
  • the inductor 9 is mutually coupled to a second inductor 13, which also includes an adjustable magnetite core 15.
  • the second inductor I3 is connected to the grid circuit of an amplifier 17, which may be any suitable thermionic tube or the like.
  • the anode circuit of the amplifier tube 11 includes a transformer !9.' This transformer is comprised of a pair of mutually coupled inductors 2
  • is shunted by a resistor 29.
  • the secondary inductor 23 is connected to the grid circuit of an amplifier 3
  • includes a transformer 33.
  • This transformer 33 is also composed of a primary inductor 35 and a mutually coupled secondary inductor 31. These inductors 35, 31, may preferably include adjustable magnetite cores 39, il
  • the secondary circuit of the transformer 33 is completed by a capacitor 43 and a shielded line 45, which is connected to the. secondary circuit at an appropriate point.
  • the shielded line is connected to a distribution network which will be described below.
  • the second (4.6-7.3 m. c.) and third (7.3-10 m. c.) channels are composed of apparatus and circuits which differ from the first channel (2-4.6 m. 0.) only in the range of frequency response, no useful purpose would be served by repeating the foregoing description. It will be observed that the shielded line 45 is connected to the output circuits of each amplifier. Additional channels (IO-12.7 m. c.'; 12.7-15.4 m. c.; 15.4-18.1 m. 0.; etc.) not shown, may be similarly included in the system.
  • the broadcast channel will be considered.
  • a single antenna 41 is connected through a transformer 49 to a transmission line 5
  • a plurality of attenuating networks 53 may be connected in the transmission line to reduce cross talk and interference caused by signal currents of high amplitude.
  • Each primary inductor 55 is mutually coupled to a resonant secondary circuit which includes an inductor 51 and a capacitor 59. Adjustable magnetite cores 6
  • terminates in a plurality of resonant circuits 53, 55, 6'1, which are connected in shunt.
  • these circuits are preferably tuned by magnetite cores 15, ll, 19..
  • These inductors 69, H, 13, are mutually coupled to secondary inductors 8
  • , 83, 85 areconnected to thermionic amplifiers 93, 95, 91.
  • the output circuit of these amplifiers in.- cludes resonant transformers 99, IM, Hi3, which are composed of primary inductors including magnetite cores and resonant secondary circuits.
  • These secondary circuits I05, I01, I09 are each comprised of capacitors and inductors which preferably have adjustable magnetite cores.
  • the secondary circuits Hi5, I01, m9 are connected to the'shielded output lead 45.
  • the combined outputs from the several separate channels may cover a very broad frequency band; forexample, 2 megacycles to 18 .1 mega.- cycles and 530 kilocycles to 1600 kilocycles. Precautions must be observed in the design of a distribution network to cover such frequency range.
  • a bifilar-wound, step-down transformer with a two toone ratiosatisfactory.
  • one bifilar-wound transformer Ill feeds into four similar transformers H3. If one of these four transformers is omitted as shown, a resistor 114' of proper terminating value may be'substituted to maintain the desired impedance match.
  • Each of the four transformers l3 in turnv is connected to four more transformers H5, which also have bifilar-two to one step-down windings.
  • the secondary windings of these transformers H5 each terminate'in four. resistorslll;
  • the input circults of the all-wave receivers are each connected to a separate one of these resistors I I1.
  • One such connection is represented by theblock H9.
  • provision has been made for sixty-four receivers. It should be understood that this distribution network may be multiplied to serve any required number of receivers. Our invention is not limited to this precis e distribution network as other arrangements may be employed.
  • each transformer consists of two tuned coupled circuits adjusted to give a slightly double peaked response of the proper band width. In each transformer one of the tuned circuits is made as low loss as possible. The selectivity factor of the other tuned circuit is adjusted to the proper value for the given band width.
  • the damping is supplied bythe surge impedance of the line which acts as a. resistance in series with the tuned circuit.
  • the inductance of the coil in series with the transmission line is the same in all short-wave input transformers.
  • the resonant frequency is varied by changing the series capacity.
  • the damping is supplied by a shunt resistor on the primary.
  • C is constant
  • R is the same in each channel to give the same band width.
  • each channel there are four tuned circuits associatedwith either the plate or. grid of a vacuum tube. In each of these circuits the tube capacity is the chief capacity of the cir-.
  • the inputtransformers have a gain of about five from the transmission line to the first'grid;
  • the interstage transformers have a gainof about. 8 from grid to grid.
  • the output transformers have a gain of about unity from'grid to line.”
  • the overall gain from line to line is about 40.
  • Figure 2 gives a performance curve'A on a typicalinput transformer.
  • Curve-B represents an interstage transformer.
  • a graph C shows the corresponding output transformer and the overall curve for the channel is designated as D. f i
  • a band width of about 350 k.c. has been found satisfactory. for this narrow band width the available gain per stage is sufficient to require only a single tubeper channel.
  • the input transformers have a gain of about 20 and the outpout transformers a gain of about 2. The principles involved in the design of these transformers are the same as for those of the short-wave channels.
  • the antenna structures may follow any conventional design, we have found dipoles resonant to the center of each frequency band most suitable for the higher frequencies.
  • the 2-4.6 m. 0. band may be served by a T antenna, which may be coupled through a suitable transformer (see reference character 49) to the transmission line.
  • the dipole antennas may be erected parallel to each other with a spacing of two feet and in a vertical or a horizontal plane.
  • One suitable arangement is to erect a pair of supportsapproximately eighty feet apart.
  • the supporting wires on the smallest dipole (26 feet) may be connected to the broadcast antenna to increase its capacity.
  • the supporting wires for the dipole of a length of 40 feet may be used to increase the capacity of the antenna used for 24.6 m. c. reception.
  • the antennas responsive to adjacent frequency bands are preferably spaced asfar from each other as possible. The foregoing antenna arrangement is illustrated in Fig. 3.
  • each such antenna isconnected to an amplifier which is substantially uniformly responsive to frequencies within the I respective channels.
  • Thebroadcast band antenna is connected to a transmission line within which attenuating networks may be included to reduce interference from signal currents of great amplitude.
  • the outputsrof the several amplifiers are connected to a common distributing network to which a plurality of all wave radio. receivers may be connected.
  • a plurality of antennas each responsive to currents of substantially different high frequencies
  • a plurality of high frequency amplifiers each responsive to different bands of frequencies of the order of 2.5 megacycles wide and including one of said antenna responsive frequencies
  • means coupling said antennas and amplifiers having similar responsive frequencies
  • an antenna responsive to currents of the broadcast frequency range a plurality of amplifiers each of which are responsive to different bands within said range of broadcast frequencies
  • means coupling said last-mentioned antenna and said last-mentioned amplifiers
  • a distributing network effectively connected to the output of said first and second mentioned amplifiers, said distributing network including a single step down transformer and four similar transformers connected to the secondary of said single transformer and a plurality of step down transformers connected in groups to the secondaries of said four transformers, and means for attenuating currents of predetermined frequency connected to the means coupling said last-mentioned antenna and said last-mentioned amplifiers.

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  • Engineering & Computer Science (AREA)
  • Signal Processing (AREA)
  • Amplifiers (AREA)
US102286A 1936-09-24 1936-09-24 Multiplex receiving system Expired - Lifetime US2151081A (en)

Priority Applications (3)

Application Number Priority Date Filing Date Title
BE423746D BE423746A (en:Method) 1936-09-24
US102286A US2151081A (en) 1936-09-24 1936-09-24 Multiplex receiving system
GB25945/37A GB504616A (en) 1936-09-24 1937-09-24 Improvements in or relating to radio receiving systems

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US102286A US2151081A (en) 1936-09-24 1936-09-24 Multiplex receiving system

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US2151081A true US2151081A (en) 1939-03-21

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US (1) US2151081A (en:Method)
BE (1) BE423746A (en:Method)
GB (1) GB504616A (en:Method)

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2500200A (en) * 1945-08-24 1950-03-14 Decca Record Co Ltd Multiple channel radio-frequency receiver
US2631238A (en) * 1949-02-16 1953-03-10 Belmont Radio Corp Antenna array
US2735988A (en) * 1956-02-21 fyler
US2738464A (en) * 1951-07-09 1956-03-13 Rca Corp Voltage divider network
US2761135A (en) * 1952-07-26 1956-08-28 Ben H Tongue Multi-signal electric system
US2761022A (en) * 1952-07-26 1956-08-28 Ben H Tongue Amplifier system
US2801295A (en) * 1951-04-23 1957-07-30 Donald R Trilling Multi-channel repeater and amplifier system
US2843828A (en) * 1951-10-18 1958-07-15 Avco Mfg Corp Ultra-high-frequency converter for very-high-frequency television receiver

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2735988A (en) * 1956-02-21 fyler
US2500200A (en) * 1945-08-24 1950-03-14 Decca Record Co Ltd Multiple channel radio-frequency receiver
US2631238A (en) * 1949-02-16 1953-03-10 Belmont Radio Corp Antenna array
US2801295A (en) * 1951-04-23 1957-07-30 Donald R Trilling Multi-channel repeater and amplifier system
US2738464A (en) * 1951-07-09 1956-03-13 Rca Corp Voltage divider network
US2843828A (en) * 1951-10-18 1958-07-15 Avco Mfg Corp Ultra-high-frequency converter for very-high-frequency television receiver
US2761135A (en) * 1952-07-26 1956-08-28 Ben H Tongue Multi-signal electric system
US2761022A (en) * 1952-07-26 1956-08-28 Ben H Tongue Amplifier system

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Publication number Publication date
GB504616A (en) 1939-04-24
BE423746A (en:Method)

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