WO1994000943A1 - Appareil de radio pour reception multi-modulation - Google Patents

Appareil de radio pour reception multi-modulation Download PDF

Info

Publication number
WO1994000943A1
WO1994000943A1 PCT/US1992/005317 US9205317W WO9400943A1 WO 1994000943 A1 WO1994000943 A1 WO 1994000943A1 US 9205317 W US9205317 W US 9205317W WO 9400943 A1 WO9400943 A1 WO 9400943A1
Authority
WO
WIPO (PCT)
Prior art keywords
constant envelope
receiver
spectral bandwidth
envelope signal
filter
Prior art date
Application number
PCT/US1992/005317
Other languages
English (en)
Inventor
Alan L. Wilson
Mark C. Cudak
Bradley M. Hiben
Eric F. Ziolko
Steven C. Jasper
Original Assignee
Motorola, 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 Motorola, Inc. filed Critical Motorola, Inc.
Priority to AU23037/92A priority Critical patent/AU2303792A/en
Priority to PCT/US1992/005317 priority patent/WO1994000943A1/fr
Publication of WO1994000943A1 publication Critical patent/WO1994000943A1/fr

Links

Classifications

    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L27/00—Modulated-carrier systems
    • H04L27/18—Phase-modulated carrier systems, i.e. using phase-shift keying
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04L—TRANSMISSION OF DIGITAL INFORMATION, e.g. TELEGRAPHIC COMMUNICATION
    • H04L27/00—Modulated-carrier systems
    • H04L27/10—Frequency-modulated carrier systems, i.e. using frequency-shift keying

Definitions

  • This invention relates generally to modulation techniques, including but not limited to constant envelope modulation techniques and non-constant envelope modulation techniques, and transmitters and receivers suitable for use therewith.
  • modulation techniques are known to support radio communications.
  • constant envelope modulation techniques such as frequency modulation (FM)
  • Non- constant envelope modulation techniques such as ⁇ /4 differential QPSK
  • Digital signalling techniques suitable for use with various modulation schemes are also known, such as ⁇ /4 differential QPSK (noted above) and 4 level FSK as used with FM.
  • Radio system users greatly desire immediate availability of digital signalling,, in part for reasons of spectral efficiency, and in part to support various desired operating features.
  • These same users do not wish to invest in currently available technology at the expense of being either foreclosed from next generation advances, or at the expense of eliminating a currently acquired digital signalling system in favor of a next generation platform.
  • system users do not wish to acquire a 4 level FSK FM system to serve immediate needs, with the likely availability of ⁇ /4 differential QPSK radios in the future.
  • a radio transceiver which transceiver includes a transmitter having a Nyquist filter, and a corresponding receiver that does not include a Nyquist filter.
  • the transmitter may be configured to transmit either a constant envelope signal, or a non-constant envelope signal, depending upon the intent of the designer.
  • the receiver functions to receive and properly demodulate either a constant envelope signal or a non-constant envelope signal. So provided, a system can accommodate a plurality of users, wherein some of the users transmit constant envelope signals and other users transmit non-constant envelope signals. Regardless of the transmission type, however, all radios are capable of receiving and demodulating all signals.
  • constant envelope transmitters can be coupled with the above receiver to allow provision of 4 level FSK radios to meet near term needs. Later, as economic issues are resolved, radios having ⁇ /4 differential QPSK transmitters can be introduced into the systf n. A system operator is therefore provided with radios that meet immediate needs, while yet retaining a compatible migration path that readily accommodates a next generation platform.
  • the constant envelope signal and the non-constant envelope signal can occupy differing spectral bandwidths. Notwithstanding this difference, the receiver can yet receive and properly demodulate both signals.
  • FIGS. 1a-b comprise block diagram depictions of prior art 4 level FSK FM transmitter and receiver structures
  • FIGS. 2a-b comprise block diagram depictions of prior art ⁇ /4 differential QPSK transmitter and receiver structures
  • FIGS. 3a-c comprise block diagram depictions of a 4 level FSK transmitter and a ⁇ /4 differential QPSK transmitter, respectively, and a receiver suitable for use with both transmitters.
  • FIG. 4 depicts IF filter design constraints
  • FIG. 5a represents the impulse response of an integrate and dump filter
  • FIG. 5b represents the frequency response of the integrate and dump filter
  • FIG. 5c represents the band limited frequency response of the integrate and dump filter.
  • FIG. 1a depicts pertinent components of a 4 level FSK transmitter (100).
  • the transmitter includes a Nyquist filter (102) designed to have a roll-off factor of 0.2.
  • the Nyquist filter (102) processes the 4 level data as a function of the square root of the raised cosine.
  • a frequency modulator (103) having a deviation index of 0.27 effectively integrates the previously filtered data, and then frequency modulates the data with respect to a predetermined carrier, as represented by e M+ ⁇ X) .
  • a DSP such as a DSP56000 family device as manufactured and sold by Motorola, Inc.
  • the blocks described, and other blocks not described but typically included in a transmitter (such as a power amplifier), are well understood by those skilled in the art, and hence further description would serve no pertinent purpose here.
  • FIG. 1b depicts relevant components for a proposed 4 level FSK receiver (125).
  • An IF filter (127) filters a received modulation signal (126), which filtered signal is then frequency demodulated.
  • the frequency demodulator includes an inverse tangent block (128) that feeds its signal to a differential summer (129), the inverting input of which couples to a unit sample delay (131). (Though described as a differential summer, this element really appears as an approximate differentiator.
  • FIG. 2a depicts a proposed ⁇ /4 differential QPSK transmitter (200).
  • a summer (202) sums this data with a feed back signal processed through a unit sample delay (203), the latter components cooperating to realize a differential encoder.
  • a phase modulator (204) then processes the j ⁇ encoded signal as a function of e to thereby yield complex in phase and quadrature components at, in this embodiment, one sample per symbol.
  • the in phase and quadrature components are then Nyquist filtered (206)
  • FIG. 2b depicts a proposed ⁇ /4 differential QPSK receiver suitable for receiving and demodulating a signal sourced by the above described transmitter (200).
  • the receiver (225) receives the modulation (266) and Nyquist filters (227) the captured signal.
  • the differential decoder (228) processes the Nyquist filtered signal as a function of an inverse tangent, and then provides the phase demodulated signal to a differential decoder (229).
  • the differential decoder (229) includes a differential summer (231) that receives the phase demodulated signal and also the phase demodulated signal as processed through a unit sample delay (232). The resultant signal is then processed in an integrate and dump filter (233).
  • a stochastic gradient bit recovery mechanism (234) then processes the decoded information to yield a 4 level data output, as generally referred to above with respect to FIG. 1b.
  • the blocks generally referred to above with respect to both the transmitter (200) and the receiver (225) for the ⁇ /4 differential QPSK modulation are relatively well understood by those skilled in the art, as well as other components that would be appropriate to complete a transmitter and receiver, such as power amplifiers, transmission elements, and the like. Therefore, no additional description need be provided here.
  • the above described constant envelope and non- constant envelope receivers and transmitters are essentially incompatible with one another.
  • the 4 level FSK FM modulation provided by the first described transmitter (100) cannot be properly recovered and decoded using the second described receiver (225). Therefore, a selection of either one or the other transmitter/receiver (100/125 or 200/225) for use in a particular system will preclude an ability to compatibly select later the previously undesignated transmitter/receiver.
  • a constant envelope transmitter suitable ⁇ for transmitting 4 level FSK FM modulation in a 12.5 kHz channel appears as generally depicted by reference numeral 300.
  • This constant envelope transmitter (300) processes incoming 4 level data (301 ) through a raised cosine Nyquist filter (302) having a roll- off factor of 0.2.
  • the previously described proposed transmitters include Nyquist filters wherein the raised cosine function appears in both the transmitter and receiver as a square root function, here the raised cosine function is not so circumscribed. Instead of distributing the Nyquist filtering between the transmitter and receiver, al Nyquist filtering, in this embodiment, occurs at the transmission end.
  • a differential encoder (303) processes the Nyquist filtered signal in a ⁇ fT band limited filter (304) as a function of sin( ⁇ fT) .
  • a particular design problem, in this embodiment, involves computing the impulse response of this filter (304).
  • H( ⁇ ) frequency response of ideal Nyquist raised cosine filter
  • the normalized corner frequency is 1 radJsec.
  • the normalized symbol time (denoted by T) is ⁇ seconds.
  • cosine (x) cosine (y) equals 0.5 cosine (x + y) + 0.5 cosine (x - y) is then used, and the integration then performed.
  • the filter function h(t) can now be sampled at discrete time intervals to realize a Nyquist raised cosine finite impulse response (FIR) filter in a DSP embodiment.
  • FIR finite impulse response
  • Dirac delta function is represented as ⁇ (t).
  • an integration function (306) completes the differential encoding process. Then, the signal can be frequency modulated as a function of
  • the resultant modulation can then be appropriately amplified and transmitted in accordance with a particular application.
  • FIG. 3b depicts a non-constant envelope transmitter (325) suitable for use in transmission of a ⁇ /4 differential QPSK signal having a bandwidth of 6.25 kHz.
  • a summer (327) receives a 4 level data input (326) and sums that with a feedback signal (328). This provides a differential encoder process as generally referred to above with respect to FIG. 2a.
  • a phase modulator (329) processes the signal and provides complex in-phase and quadrature components at one sample per symbol. These components are then filtered in a raised cosine Nyquist filter (331 ).
  • this raised cosine Nyquist filter (331 ) has a roll-off factor of 0.2, and does not process the signal as a function of a square root of the raised cosine. Instead, all Nyquist processing from source to destination occurs in the transmitter (325). Subsequent to Nyquist filtering, a mixer (332) mixes the information signal with an appropriate carrier frequency (333) and the desired ⁇ /4 differential QPSK modulation results.
  • FIG. 3c depicts a receiver suitable for use in receiving and decoding modulation from either of the above described ' transmitters (300 and 325). Received modulation (351) couples to a loose IF filter (352).
  • the IF design must accommodate a pass bandwidth wide enough and flat enough to avoid intersymbol interference while having a stop bandwidth that is narrow enough to allow 6.25 kHz channel spacing.
  • the constraints on the filter design are presented in FIG. 4 for a system with 9600 bits/second of throughput in a 6.25 kHz channel.
  • a Nyquist raised cosine filter having a roll- off factor of 0.2 appears in the transmitter.
  • the stop bandwidth limit is 6.25 kHz while the pass bandwidth limit is designed to exceed
  • stop bandwidth 6.25 m _, 0g5 pass bandwidth 5.76 ⁇
  • the loose IF filter uses two FIR filters in a DSP embodiment.
  • a decimating filteT first narrows the bandwidth enough to reduce the sample rate for introduction to the subsequent filter, the latter providing a rapid filter roll-off.
  • Both FIR filters in this embodiment are equi-ripple designs.
  • the first FIR iilter attains 80 db of stop band rejection with a stop frequency of 4.68 kHz and a pass frequency of 3 kHz.
  • the second FIR filter has a stop frequency of 3.00 kHz and a pass frequency of 2.88 kHz. Parameters for both FIR filters appear in Table 2, below.
  • a frequency demodulator (353) demodulates constant envelope information.
  • the frequency demodulator includes an inverse tangent block (354), a differential summer (356) and a unit sample delay path (357) as essentially described above with respect to the proposed 4 level FSK receiver (125).
  • the receiver (350) also includes a differential decoder (358) substantially as described above for the ⁇ /4 differential QPSK receiver (255), inclusive of the unit sample delay path (357) and the differential summer (356), in conjunction with an integrate and dump filter (359).
  • the integrate and dump filter essentially comprises a linear filter that integrates over a predetermined sample period and then di nps historical data in preparation for a new integration window.
  • the impulse response for the integrate and dump filter appears in FIG. 5a, where the vertical scale represents normalized amplitude and the horizontal scale represents normalized time in seconds for T ⁇ 1 second.
  • a corresponding frequency response (reflective of the sin( ⁇ fT) familiar ⁇ fT filter response) appears in FIG.
  • the impulse response for this filter (359) can be directly calculated with an inverse Fourier transform.
  • a closed form solution can be expressed in terms of the sine integral function Si (X) as shown below.
  • the receiver provides no Nyquist filtering. All Nyquist filtering occurs in the transmitters. (The rolloff ratio constitutes the important variable to be controlled in a Nyquist filter. In prior art transceivers using Nyquist filters, this ratio must be identical for both the transmitter filter and the receiver filter.
  • the receiver is independent of this variable, and can receive signals from different transmitters that use different values for the rolloff ratio.
  • the receiver can effectively demodulate and recover either constant envelope signals or non-constant envelope signals, such as 4 level FSK FM or ⁇ /4 differential QPSK linear modulation.
  • this receiver can accommodate these alternative modulation types, notwithstanding differing channel widths, in this case 12.5 kHz and 6.25 kHz, respectively.
  • a system operator can select to realize the advantages of digital signalling by fielding 4 level FSK FM transmitters coupled with the described compatible receiver.
  • the operator can introduce such transmitters into a system in conjunction with the same compatible receiver as used for the constant envelope transceivers. Notwithstanding differing modulation types and differing bandwidth requirements, the same receiver platform allows compatible communication between these differing units.

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  • Engineering & Computer Science (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • Signal Processing (AREA)
  • Digital Transmission Methods That Use Modulated Carrier Waves (AREA)

Abstract

Un récepteur (350) conçu pour la réception en modulation FM FSK à 4 niveaux à canal large et à enveloppe constante et en modulation linéaire différentielle π/4 QPSK à canal étroit permet une interaction compatible entre des émetteurs modifiés à enveloppe constante et à enveloppe non constante (300). Tout le filtrage Nyquist se fait dans les émetteurs (300), aucun dans le récepteur (350).
PCT/US1992/005317 1992-06-23 1992-06-23 Appareil de radio pour reception multi-modulation WO1994000943A1 (fr)

Priority Applications (2)

Application Number Priority Date Filing Date Title
AU23037/92A AU2303792A (en) 1992-06-23 1992-06-23 Multi-modulation scheme compatible radio
PCT/US1992/005317 WO1994000943A1 (fr) 1992-06-23 1992-06-23 Appareil de radio pour reception multi-modulation

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
PCT/US1992/005317 WO1994000943A1 (fr) 1992-06-23 1992-06-23 Appareil de radio pour reception multi-modulation

Publications (1)

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WO1994000943A1 true WO1994000943A1 (fr) 1994-01-06

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Cited By (13)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0690598A3 (fr) * 1994-06-30 1997-10-01 Sony Corp Système de transmission "QPSK" infrarouge
EP0881806A2 (fr) * 1997-05-29 1998-12-02 Alcatel Structure de trâme avec plusieurs types de modulation
WO2000010301A2 (fr) * 1998-10-13 2000-02-24 Telefonaktiebolaget Lm Ericsson (Publ) Conduction de signal a dephasage dans un systeme de communication numerique
FR2803969A1 (fr) * 2000-01-13 2001-07-20 Sagem Equipement d'emission radio et equipement de reception radio
FR2803970A1 (fr) * 2000-01-13 2001-07-20 Sagem Equipement d'emission radio et equipement de reception radio
EP2177521A1 (fr) 2008-10-14 2010-04-21 Almirall, S.A. Nouveaux dérivés de 2-amidothiadiazole
EP2202232A1 (fr) 2008-12-26 2010-06-30 Laboratorios Almirall, S.A. Dérivés du 1,2,4-oxadiazole et leur application thérapeutique
WO2010081692A1 (fr) 2009-01-19 2010-07-22 Almirall, S.A. Dérivés d'oxadiazole comme agonistes du récepteur s1p1
WO2011035900A1 (fr) 2009-09-25 2011-03-31 Almirall, S.A. Nouveaux dérivés de thiadiazole
WO2011069647A1 (fr) 2009-12-10 2011-06-16 Almirall, S.A. Nouveaux dérivés de 2-aminothiadiazole
EP2366702A1 (fr) 2010-03-18 2011-09-21 Almirall, S.A. Nouveaux dérivés d'oxadiazole
WO2011144338A1 (fr) 2010-05-19 2011-11-24 Almirall, S.A. Dérivés du pyrazole en tant qu'agonistes s1p1
JP2014003528A (ja) * 2012-06-20 2014-01-09 Tokai Rika Co Ltd Ｆｓｋ復調器

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4601048A (en) * 1984-04-02 1986-07-15 Ryan Carl R Serial minimum shift-keyed modem
US4720839A (en) * 1986-12-02 1988-01-19 University Of Ottawa Efficiency data transmission technique
US4731796A (en) * 1984-10-25 1988-03-15 Stc, Plc Multi-mode radio transceiver
US4843615A (en) * 1987-05-08 1989-06-27 Harris Corp. CPFSK communication system employing nyquist-filtered modulator/demodulator

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4601048A (en) * 1984-04-02 1986-07-15 Ryan Carl R Serial minimum shift-keyed modem
US4731796A (en) * 1984-10-25 1988-03-15 Stc, Plc Multi-mode radio transceiver
US4720839A (en) * 1986-12-02 1988-01-19 University Of Ottawa Efficiency data transmission technique
US4843615A (en) * 1987-05-08 1989-06-27 Harris Corp. CPFSK communication system employing nyquist-filtered modulator/demodulator

Cited By (22)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0690598A3 (fr) * 1994-06-30 1997-10-01 Sony Corp Système de transmission "QPSK" infrarouge
EP0881806A2 (fr) * 1997-05-29 1998-12-02 Alcatel Structure de trâme avec plusieurs types de modulation
EP0881806A3 (fr) * 1997-05-29 2002-04-03 Alcatel Structure de trâme avec plusieurs types de modulation
WO2000010301A2 (fr) * 1998-10-13 2000-02-24 Telefonaktiebolaget Lm Ericsson (Publ) Conduction de signal a dephasage dans un systeme de communication numerique
WO2000010301A3 (fr) * 1998-10-13 2000-06-02 Ericsson Telefon Ab L M Conduction de signal a dephasage dans un systeme de communication numerique
US6473506B1 (en) 1998-10-13 2002-10-29 Telefonaktiebolaget Lm Ericsson (Publ) Signaling using phase rotation techniques in a digital communications system
FR2803969A1 (fr) * 2000-01-13 2001-07-20 Sagem Equipement d'emission radio et equipement de reception radio
FR2803970A1 (fr) * 2000-01-13 2001-07-20 Sagem Equipement d'emission radio et equipement de reception radio
EP2177521A1 (fr) 2008-10-14 2010-04-21 Almirall, S.A. Nouveaux dérivés de 2-amidothiadiazole
WO2010072352A1 (fr) 2008-12-26 2010-07-01 Almirall S.A. Dérivés de 1,2,4-oxadiazole et leur utilisation thérapeutique
EP2202232A1 (fr) 2008-12-26 2010-06-30 Laboratorios Almirall, S.A. Dérivés du 1,2,4-oxadiazole et leur application thérapeutique
WO2010081692A1 (fr) 2009-01-19 2010-07-22 Almirall, S.A. Dérivés d'oxadiazole comme agonistes du récepteur s1p1
EP2210890A1 (fr) 2009-01-19 2010-07-28 Almirall, S.A. Dérivés d'oxadiazoles en tant qu'agonistes du récepteur S1P1
WO2011035900A1 (fr) 2009-09-25 2011-03-31 Almirall, S.A. Nouveaux dérivés de thiadiazole
EP2305660A1 (fr) 2009-09-25 2011-04-06 Almirall, S.A. Nouveaux dérivés de thiadiazole
WO2011069647A1 (fr) 2009-12-10 2011-06-16 Almirall, S.A. Nouveaux dérivés de 2-aminothiadiazole
EP2343287A1 (fr) 2009-12-10 2011-07-13 Almirall, S.A. Nouveaux dérivés de 2-aminothiadiazole
EP2366702A1 (fr) 2010-03-18 2011-09-21 Almirall, S.A. Nouveaux dérivés d'oxadiazole
WO2011113578A1 (fr) 2010-03-18 2011-09-22 Almirall, S.A. Nouveaux dérivés d'oxadiazole
WO2011144338A1 (fr) 2010-05-19 2011-11-24 Almirall, S.A. Dérivés du pyrazole en tant qu'agonistes s1p1
EP2390252A1 (fr) 2010-05-19 2011-11-30 Almirall, S.A. Nouveaux dérivés de pyrazole
JP2014003528A (ja) * 2012-06-20 2014-01-09 Tokai Rika Co Ltd Ｆｓｋ復調器

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Publication number Publication date
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