US1931038A - Telegraph system - Google Patents

Telegraph system Download PDF

Info

Publication number
US1931038A
US1931038A US505075A US50507530A US1931038A US 1931038 A US1931038 A US 1931038A US 505075 A US505075 A US 505075A US 50507530 A US50507530 A US 50507530A US 1931038 A US1931038 A US 1931038A
Authority
US
United States
Prior art keywords
frequency
band
carrier
signal
frequencies
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
US505075A
Other languages
English (en)
Inventor
Starr Arthur Tino
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
Western Electric Co 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
Application filed by Western Electric Co Inc filed Critical Western Electric Co Inc
Application granted granted Critical
Publication of US1931038A publication Critical patent/US1931038A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L27/00—Modulated-carrier systems
    • H04L27/02—Amplitude-modulated carrier systems, e.g. using on-off keying; Single sideband or vestigial sideband modulation

Definitions

  • the total 55 this corresponds to systems in which two voltage time elapsing from the commencement of the or current values, for example, positive and negareeeived Signal C0 the Point Where the Current tive, or positive and Zero, etc., are used to trans- Value beCOineS Substantially negligible iS Nt time mit the intelligence.
  • carrier telegraph sysnnitS v l0 tems (that is, where the signals are used to modu-
  • the Signal frequencies may be defined aS lhOSe H0 ist@ asteady carrier frequencw the twoy condi- ⁇ which would be produced by the transmitters@- tions are ⁇ in general, for example, full carrier and ing On a' direct Cuilenl SOnleel Y no carrier.
  • i Y l p K A feature of the inventionis a telegraph system It has previously been suggested to transmit wherein the band of frequencies transmitted has 'T5' telegraph messages by a system analogous to ⁇ that a widthI numerically less than the dot frequency, Q51
  • ther transmitted band should extendfrom necessary to transmita band 0f Signal frequen- D ⁇ to s periods per second, where s is the dot frecies of Width Y 'A n 70 quency. From this it follows that after module# tion the frequency nearest the carrier in each .f side band coincides with the carrier frequency.
  • pnasmg gence-bearing band of frequencies can be sepa,- arrangeinentsto cancel out frequencies of the unwanted side bands which would cause interrated from the carrier andiother frequens by .30V ference.
  • a' Carrier telegraph System 1s provlded m mation Wm be defined as follows; which the carrier wave and Vone side band4 are 85V i' the intelligence- A unit of intelligence (that is, a letter or sym- Completely suppl-ssed and .f boi) is made up' of a number (Say N) of Signal bearing band of width less thans are transmitted 1' L i f v only. Y elements occupying a total time T seconds.
  • a telegraph system is provided wherein 90 persisting for a definite time called a time unit.
  • V alltime units are of equal duration.
  • the unit of intelligence contains N signalyelements occupying antotal time T ⁇ seconds, a time unit is lequal toT/N seconds.
  • the 4clot frequency is defined ,as arfrequency is transmitted along with the intelligence-bearing-band nearest thevcarrier, a portion kof unmodulated carrier. Y v. q y
  • the first factors in both expressions of (7) are identical form with S(q) given in (4) and is the shape-factor for the D. C. wave.
  • the second factors in the expressions are the discrimination factors and carry the intelligence conveyed by the signals; the shape-factor may be anything so long as it is knownand does not vanish at any frequency at which we wish to know the discrimination factors.
  • the discrimination factors may be taken as l l
  • preceding and succeeding signals are to lump the spectrum in the vneighborhood 0f certain frequencies; the worst possible interference occurring when the precedv ing and succeeding signals are the same as the mid signal, in which case the lumping is complete at the frequencies given bythe frequencies of the representative Fourier series. else the amplitude falls to zero.
  • Such areceiving instrument may be, for' example, a siphon recorder or an oscillograph.
  • frequencies 2s ⁇ /5 and L1s/5 or 6s/5 Vand 8.9/5 or suffice cas shown inl Fig. 4. These correspond to valuesof n 1 and 2, 3 and 4,6 and 7 (5r-l-l) and (5 ⁇ r+2), (5r+3) and (5r+4) respectively;
  • Fig. 5 shows a D, C. system in block form.
  • D. C. transmitter DCTi works ata dot frequency of s1, and uses a band widthselecteclby the band pass filter BPFl, of
  • DCTs works at the same dot frequency but uses a band width of 2s y l Nt t0 381. V .v
  • All the remaining odd channels use the dot frequency s1 and band widths respectively 231 apart.
  • Y Channel 1 from DCT1 to R1 is more or less in the nature of a D. C. telegraph channel, butdiifers A in that frequencies'belowv j need not be transmitted.
  • the other channels, although sent ⁇ by a D. C. transmitter, are more like carrier telegraph channels. There is a consequent saving, for only one modulator is needed to send these channels, whereas inA ordinary carrier telegraphy'a modulator is needed at the sending of the channels.,Y v Y135K
  • frequency-translating devices i. e.Y de-modulators D2 and D3 etc., arey needed in channels 2, 3 etc., at the receiving end as shown.
  • the correcting networks CN1, CNz, CNS applyfboth attenuation and phase shift adjustments q in known manner, to give the desired received wave.
  • Fig. 6 shows how this may be carried out. Instead of passing channels 1, 2, 3, etc., directly out on to thejline, they can be passed in to a modulator of acertain carrier frequency fc andv translated up in the frequency spectrum by a It is now comparatively easy to transmit a single side band for each channel, because the intelligence bearing bands are separated from the carrier frequency, which can thus be easily suppressed. In Fig. 6 it will be assumed that it lis required to transmit the upper side band.
  • the D. C. transmitter DCT supplies signals to the band pass lter BPFa ⁇ which selects aband of the corresponding width from 2 3 N l l I t to s, and passes this band on to thev modulator M supplied with a carrier frequency fc.
  • the incoming frequency band passes through a similar band pass filter BPFc and the passed band is de-modulated (i. e. translated down in the frequency spectrum) in the de-inodulator DW supplied with a frequency je.
  • the .output from the demodulator passes through a band pass lter BPFd which selects the desiredbandof l Nt H to s, which after passing through the correcting network CN which supplies the necessary atten'- uation and phase adjustment, is applied to the n d quency, and which', in its normal'positionlintheV Fig. 6 is. to make the signal modulate the carrier. directly receiver R.
  • An alternative method lof transmission consists in sending a separate message in each of the side bands of a single carrier with a portion of unmodulated carrier transmitted in additionV vto the side bands.
  • O ⁇ is an oscillator which provides thenece'ssary carrier frequency. Thisis fed into two transmitters T1 andfTZ and also into the line Ldirect through the band pass filter BPF. rBPll' lets throughthe flower side band and 'BPFZ the upper'side band;A '#Phase Shifters ⁇ PS1 and PS2 vserve the purpose' ⁇ of 'cor-f recting thefchanges '(at' different frequencies) ⁇ due tothe'band pass filters.
  • each of the band-pass filters vBlVFS"andlBPFlV lets throughone side band with a part ofthe u n' modulated carrier'.
  • Each 'side band is adjusted for ⁇ attenuation and phase shift A.due to 4the-:line and band pass filters BPF3 and BPF4', this being provided for in equalizers E3 and E4 and 100 phase Shifters PS3 and PS4.
  • the receiver as in 4'the case ofthe pre- 105 ceding examples, may be any suitable telegraph receiver, for example, ⁇ aVsiphon recorder, teleprinter recording oscillograph -or any sensitive recorder.
  • V' Y f In order to minimize interference between the channels ⁇ but at thesame time to receive as large a 'carrier as possiblejfor obtaining as strong a signal for demodulation purposes as Apossible, the" sendingfilters vBPFl' and BPF2 should havefat-i tenuation characteristics as 'shown' in ⁇ lFig. 8 ⁇ 115 since the form of the ycharacteristics of 'BPF1-" and BPFZ are such'v as tominimize interference between the channels and the forms of the char# ⁇ actersitics of VBPF3 and BPF4" are such as to separate theA bands ⁇ andV let through amoderatee ly large'portionfof the carrier-'to each channel. ⁇
  • multiplef is used in the generic sense to include single wellfas 1302m plural multiples'. e.l g., the' expression "multiple of the dot frequency may include the dot fre? quency itself. 1 What is claimed' is :"f
  • a telegraph 'system comprising means for V13.5,
  • each signal element to complywith' one of two known electrical conditions that are used to transmit the intelligence, ⁇ andA frequency selec- ⁇ tive'means for selecting from the signaling waves," for transmission, frequencies of af band which-140'? has width numericallysmaller than the dot 'fre-' cal conditions that are used to transmit the in.
  • a telegraph system as claimed in claim 2 comprising frequency-translating means for in the transferring to a given position in the frequency spectrum va frequencyband as specied inclaim 2. 4.
  • a direct current telegraph system comprising message channels and frequency selective means in said channels for selecting for trans- .mission in the respective channels respective frequency bands of width l s N, n spaced throughout the frequency spectrum so that successive bands include successive odd integral multiples of s, Where s is the dot frequency j and N: is a number as defined in the specification.
  • a telegraph system comprising a group of message channels and a group of direct current telegraph transmitters therefor of one dot frequency, asecond group of message channels and a second group of direct current telegraph transmitters therefor having a higher dot frequency, frequency Iselective means in said first channel group selecting from the signalwaves in its channels, for transmission in the respective channels vofy that group, frequency bands each of width numerically smaller than the dot frequency for that channel group and each with an odd. integral multiple of that dot frequency as a limiting frequency, and frequency selective means vin -said second channelgroup for vselecting .from the sig-- nal waves in its channels, for transmission in the respective channels of that group, frequency bands alternating in order in the frequency scale:
  • a telegraph system comprising a transmis- ⁇ Asion line, a plurality of direct current telegraph transmitters, band-pass filters respectivelyconnecting said transmitters to said line, each filter passing a frequency band lying in a different portionv of the frequency spectrum and having a ⁇ band width Vnumerically smaller than the dot frequency of its transmitter, and signal receiving means connected to said line and comprising signal receiving channels, filters corresponding v respectively to said first mentioned filters conjnected in said receiving channels respectively,V and frequency vtranslating means connected in 6.
  • AV direct currentY telegraph system las.
  • a carrier wave telegraph transmitting system comprising a carrier wave transmission circuit, a source of carrier telegraph signaling waves, Aand'frequency selective means c onnecting said source to said circuitfor selecting from said signaling Waves, for transmission to said circuit, ⁇ rfrequencies of a band which-has width numerically less than the dot frequency and vwhich has as one of its limiting frequencies a frequency algebraically differing from thecarrier frequencyby an odd integral multiple of the dot frequency.
  • a system comprising means for producing carrier telegraph signal waves, a carrier telegraph transmission circuit, frequency selective means for selecting from said signaling waves,l
  • Ihe ⁇ method which comprises transmitting carrier wave telegraph signals as a hand of frethe dot frequency and that has an odd integral multiple of .the dot frequency as one of the boundaries of the vsignal frequencies..
  • the methodoftransmitting Asignals in code which comprises transmitting each of the signal elements in compliance with either of two electrical conditions either of which they are known to fulfill, and transmitting each o f the signal lelements as wave components embraced in the same frequency band having width numerically smaller than the dot frequency and having an odd vinte'-Y gral multiple of the dot frequency as one limiting frequency.

Landscapes

  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Mobile Radio Communication Systems (AREA)
  • Cable Transmission Systems, Equalization Of Radio And Reduction Of Echo (AREA)
US505075A 1930-01-24 1930-12-27 Telegraph system Expired - Lifetime US1931038A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB2524/30A GB347265A (en) 1930-01-24 1930-01-24 Improvements in or relating to telegraph transmission systems

Publications (1)

Publication Number Publication Date
US1931038A true US1931038A (en) 1933-10-17

Family

ID=9741065

Family Applications (1)

Application Number Title Priority Date Filing Date
US505075A Expired - Lifetime US1931038A (en) 1930-01-24 1930-12-27 Telegraph system

Country Status (4)

Country Link
US (1) US1931038A (en(2012))
BE (1) BE376154A (en(2012))
DE (1) DE577155C (en(2012))
GB (1) GB347265A (en(2012))

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3761622A (en) * 1970-11-23 1973-09-25 Us Interior Amplitude modulated telemetering system

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3761622A (en) * 1970-11-23 1973-09-25 Us Interior Amplitude modulated telemetering system

Also Published As

Publication number Publication date
BE376154A (en(2012))
GB347265A (en) 1931-04-24
DE577155C (de) 1933-05-30

Similar Documents

Publication Publication Date Title
US3511936A (en) Multiply orthogonal system for transmitting data signals through frequency overlapping channels
US3678204A (en) Signal processing and transmission by means of walsh functions
US3443229A (en) Quadrature-carrier vestigial-sideband data transmission
US2408692A (en) Signaling system
US2213941A (en) Multiplex signaling by phase discrimination
US3343093A (en) Dual-channel quadrature-modulation pulse transmission system with dc component transmitted in separate channel
US3423529A (en) Automatic phase recovery in suppressed carrier quadrature modulated biternary communication systems
US2021743A (en) Multiplex signaling
US3723880A (en) System for the transmission of multilevel data signals
US3611143A (en) Device for the transmission of rectangular synchronous information pulses
US2709218A (en) Method and means for anti-jamming in radio
US2583484A (en) Combined angular velocity and pulse modulation system
US4217467A (en) Amplitude and periodic phase modulation transmission system
US5748036A (en) Non-coherent digital FSK demodulator
US3564412A (en) Derived clock from carrier envelope
US3349181A (en) Phase shift modulation radio communication system
US1931038A (en) Telegraph system
US3766480A (en) Device for recovering a frequency showing phase jitter
US3378770A (en) System for quadrature modulation of ternary signals with auxiliary oscillation for use in carrier regeneration at receiver
US2213320A (en) Privacy system
US3701852A (en) Transmission system and associated transmitters and receivers for the transmission of synchronous pulse signals
US1797317A (en) Binaural phase-discrimination radio system
US3517131A (en) System for superimposing individual channel spectra in a noninterfering manner
US2299388A (en) Radio communication system
US3421089A (en) Circuits for reducing distortion in a demodulator for data transmission