Patent EA-001394-B1 (EA)
Title: Method for wireless information transfer
Inventor: KOSLAR MANFRED
IPC: H04B1/69
Filed: 1997-11-03
Abstract: 1. Method for wireless transfer of information, in particular for mobile communications, wherein an input signal (s1, g4) is subjected to an angle modulation in a transmitter (2 to 8; 16 to 26) and reaches a receiver (11 to 15; 29 to 57) through a transmission channel, whereby angle modulated pulses, possessing a frequency spectrum and carrying information, are generated in the transmitter in such a way, that they can be time compressed in the receiver using a filter (13, 32, 33) with frequency dependent, differential delay time, also referred to as group delay, in such a way that pulses are created with shortened duration and increased amplitude, compared to the emitted pulses, and at least a portion of the information in the transmitter is imprinted onto the pulses using an additional modulation, independent of the angle modulation, and/or is used for controlling a parameter of the angle modulation that can be measured in the receiver, whereby at first a sequence of quasi- Dirac pulses is generated in the transmitter and fed to a low-pass filter, the filter characteristic of which possesses a peak shortly before the critical frequency, and which thus transforms the delta-pulse sequence into a series of Sinc-pulses, the shape of which is described by the Sinc-function Sinc(x) = sin(x)/x, which is subsequently carried to an amplitude modulator that imprints the Sinc-shaped envelope onto each pulse of a carrier oscillation, and the signal generated in this manner is fed to a dispersive filter, at the output of which arrives a frequency modulated pulse sequence. 2. Method of claim 1, whereby the angle modulation and the additional modulation method are modulation types that are at least approximately orthogonal. 3. Method of claim 1 or 2 whereby the pulses are filtered according to a default filter characteristic, whereby the angle modulation on the transmitter side and the group delay response of the dispersion filter (13, 32, 33) on the receiver side are matched in such a way that the signal components of the angle modulated pulses (s6) of the output signal (s9, s14) arrive at the output of the dispersion filter, due to the filter's frequency dependent variable signal delay time, essentially coincident and, due to the superposition, with increased amplitude compared to the input. 4. Method of one of the previous claims whereby the input signal (g4) possesses a carrier frequency, which is subjected pulse by pulse to an angle modulation in the transmitter (16 to 26). 5. Method of claim 4 whereby the modulation characteristic of the angle modulation determines the time variation of the phase angle during the duration of each pulse, the amplitude of the angle modulated pulses in particular is used for the imprinting of the information contained in the input signal (s1), depending on the input signal (s1), the group delay response of the dispersion filter (13) in the receiver (11 to 15) is complementary to the frequency-time characteristic of the transmission pulse, and the amplitude of the pulse arriving compressed from the dispersion filter (13) is evaluated for recovery of the information contained in the input signal (s1) using a detector (14, 15), in particular an amplitude demodulator. 6. Method of one of the previous claims whereby the additional modulation method that imprints the information is, in particular, a pulse position modulation (PPM), or optionally a pulse code modulation (PCM), or a differential pulse code modulation (DPCM), or a pulse delta modulation (PDM), or a modification of one or several of these modulation methods. 7. Method of one of claims 3 to 6 whereby the pulse sequence, angle modulated in the transmitter, is fed to a pair of dispersion filters (32, 33) in the receiver (29 to 37), whereby the pair of dispersion filters (32, 33) possess different group delay responses which are matched in pairs to the modulation characteristic in such a way, that the signal components of the pulses arrive with increased amplitude at the output of only one of the dispersion filters (32, 33), while such an increase in amplitude does not take place for the other dispersion filter (33, 32), and the amplitudes are evaluated comparatively at the output of the dispersion filters (13, 32, 33) using a detector (14, 15, 34, 35). 8. Method of claim 7 whereby the angle - the frequency or the phase - of the carrier frequency changes, during the pulse duration of the pulse modulated signals, linearly with time, monotonically from a lower frequency or phase position to an upper frequency or phase position, or in reverse direction, and the dispersion filter in the receiver possesses a complementary linear or monotonic response. 9. Method of one of the previous claims whereby the modulation characteristics for the individual pulses of a series of pulses are selected differently in such a way that the differences contain part of the information. 10. Method of one of the previous claims whereby, for matching of transmitter (2 to 8, 16 to 26) and receiver (11 to 15, 29 to 37), a default digital reference signal is transmitted as input signal (s1, g4) as alignment during the matching process, during the matching process the amplitude or the pulse duration of the output signal (s7, g10, g11) of the dispersion filter (13, 32, 33) on the receiver side is measured, and the modulation characteristic used on the transmitter side, or the group delay response of the dispersion filter (13, 32, 33) on the receiver side, is varied, until the pulse duration reaches a minimum value, or the amplitude reaches a maximum value. 11. Method of one of claims 7 to 10 whereby the signal flow in the receiver is split into two parallel branches, each with two dispersion filters (39, 44, 40, 43) with group delay characteristics that are inverse with respect to each other, the signal flow in the two branches is connected through or interrupted for a predetermined time interval during each pulse, whereby the interruption or connection occurs synchronous with the transmission timing rate, and the two branches are joined on the output side by a subtracter (45). 12. Transmitter and receiver arrangement for implementing the method of one of the previous claims, comprising a transmitter (2 to 8, 16 to 26) for pick-up and transmission of an input signal (s1, g4), containing a first modulator (2 to 6, 16 to 24) for angle modulation of the input signal (s1, g4), as well a receiver (11 to 15, 29 to 37), containing a demodulator (14, 15, 31 to 37) for recovery of the input signal (s1, g4), whereby the transmitter contains means for generating a quasi- Dirac pulse sequence and, connected to it on the input side, a low-pass filter, the filter characteristic of which possesses a peak shortly before the critical frequency, and thus transforms the delta-pulse sequence into a series of Sinc-pulses, the shape of which is described by the Sinc-function Sinc(x) = sin(x)/x, and contains further, connected to the output of the low-pass filter, an amplitude modulator, which imprints the Sinc-shaped envelope onto a carrier oscillation, and a dispersion filter connected to the output of the amplitude modulator, the first modulator (2 to 6, 16 to 24) generates angle modulated pulses according to a modulation characteristic that determines the time variation of the angle or phase position during the duration of each pulse, the first modulator (2 to 6, 16 to 24) contains a control input for the pick-up of the input signal (s1, g4) and for the setting of the modulation characteristic depending on the input signal s1, g4, and/or the transmitter (2 to 8, 16 to 26) contains a second modulator (4) for an additional modulation of the angle modulated pulses depending on the input signal (s1, g4), the receiver (11 to 15, 29 to 37) contains a dispersion filter (13, 32, 33), in particular a surface acoustic wave filter, with a default group delay response for filtering the pulses, angle modulated on the transmitter side, according to the default modulation characteristic, and the group delay response of the dispersion filter (13, 32, 33) is matched, for an increase in amplitude of the output signal (s9, g14), to the modulation characteristic used on the transmitter side in such a way that the signal components of the pulses, angle modulated according to this modulation characteristic, arrive time compressed and with an amplitude enhancement at the output of the dispersion filter (13, 32, 33), due to the filter's frequency dependent, variable signal delay time. 13. Arrangement of claim 12 whereby the first modulator (16 to 24) generates a series of angle modulated pulses, whereby the angle modulation is carried out depending on the input signal (g4) at the control input, either according to a default first modulation characteristic or according to a second default modulation characteristic, the receiver (29 to 37) contains two dispersion filters (32, 33) connected in parallel, whereby the variable group delay response of the two dispersion filters (13, 32, 33) and the first and second modulation characteristics are matched in such a way that the signal components of the angle modulated pulse sequence arrive time compressed and with increased amplitude at the output of exactly one of the two dispersion filters (13, 32, 33). 14. Arrangement of claim 12 or 13 whereby  the first modulator (16 to 24) on the transmitter side contains one dispersion filter (22, 23) each for generating the angle modulation pulses according to the two modulation characteristics, the dispersion filters (22, 23) arranged in the first modulator (16 to 24) are connected on the input side by a controllable switching element (21) to a signal source (16 to 20), which generates a high frequency signal (g3) with essentially Sinc-shaped envelope, the switching element (21), for triggering by the input signal (g4), is connected to the control input of the modulator (16 to 24). 15. Arrangement of claim 12 or 13 whereby