US3795865A
Expired / Lapsed
US
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Automated real time equalized modem
Assignee: Bull HN Information Systems Italia SpA
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Filing: 1972-02-23
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Granted: 1974-03-05
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Expires: 1992-02-23
Abstract
Abstract An Automated Real Time Equalized Modem (ARTEM) having multipath equalization by means of adaptive, quadrature matched filters and an adaptive transversal equalizer. ARTEM is a wideband (3kHz) system employing multilevel PAM-VSB (Pulse Amplitude ModulationVestigial Side Band) modulation and continuous real-time automatic channel measurement and equalization, wherein the channel pulse response is continually measured and equalized so that the modem receiver adapts itself to the varying HF medium.
Inventors
- 👤 T Armstrong
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-27 17:27
CPC Classifications
H; H04; H04L; H04L25/00; H04L25/02; H04L25/03; H04L25/03006; H04L25/03012; H04L25/03114; H04L25/03133; H04L27/00; H04L27/02; H04L27/06; H04L27/066
Claims Analysis
Total Claims: 24
Claim 1
Independent Claim
243 words
An ARTEM system employing multilevel pulse amplitude modulation vestigial side band (PAM-VSB) modulation and continuous real-time automatic channel measurement and equalization of time variants of propagation characteristics of the channel comprising: a. modulation means for providing at least eight levels PAM-VSB modulation; b. pseudo-noise (PN) sequence generator means coupled to said modulation means said PN generator for generating PN signal sequences of predetermined length; c. transmitter means, coupled to said modulation means, for transmitting modulated signals; d. receiver means responsive to said transmitter means for receiving the transmitted signals, said receiver means further comprising: Alpha . signal processor means for processing the received modulated signal, said signal processor means further comprising quadrature demodulator means for demodulating the received signal into in-phase and quadrature demodulated signal components, adaptive matched filter means coupled to said quadrature demodulator means and responsive to the PN signal sequence for compensating for residual carrier phase inaccuracies, summing means coupled to said adaptive matched filter means, for summing the in-phase and quadrature signal components, and adaptive transversal equalizer means coupled to said summing means having adjustable tap gains for controllably eliminating intersymbol interference; Beta . phase correction and carrier recovery means for correcting phase and recovering the received signal, said phase correction and carrier recovery means coupled to said signal processor means; and, gamma . data detect and error correction means for converting a predetermined number of quantization levels to at least eight, and detecting and correcting the coding erros.
Claim 2
Dependent Claim
243 words
An ARTEM system employing multilevel pulse amplitude modulation vestigial side band (PAM-VSB) modulation and continuous real-time automatic channel measurement and equalization of time variants of propagation characteristics of the channel comprising: a. modulation means for providing at least eight levels PAM-VSB modulation; b. pseudo-noise (PN) sequence generator means coupled to said modulation means said PN generator for generating PN signal sequences of predetermined length; c. transmitter means, coupled to said modulation means, for transmitting modulated signals; d. receiver means responsive to said transmitter means for receiving the transmitted signals, said receiver means further comprising: Alpha . signal processor means for processing the received modulated signal, said signal processor means further comprising quadrature demodulator means for demodulating the received signal into in-phase and quadrature demodulated signal components, adaptive matched filter means coupled to said quadrature demodulator means and responsive to the PN signal sequence for compensating for residual carrier phase inaccuracies, summing means coupled to said adaptive matched filter means, for summing the in-phase and quadrature signal components, and adaptive transversal equalizer means coupled to said summing means having adjustable tap gains for controllably eliminating intersymbol interference; Beta . phase correction and carrier recovery means for correcting phase and recovering the received signal, said phase correction and carrier recovery means coupled to said signal processor means; and, gamma . data detect and error correction means for converting a predetermined number of quantization levels to at least eight, and detecting and correcting the coding erros.
Claim 3
Dependent Claim
21 words
An ARTEM system as recited in claim 1 wherein said adaptive matched filters each have a filter length of 63 stages.
Claim 4
Dependent Claim
19 words
An ARTEM system as recited in claim 2 wherein said adaptive transversal equalizer has a length of 65 stages.
Claim 5
Dependent Claim
32 words
An ARTEM system as recited in claim 3 wherein the matched filter includes a predetermined number of taps which are varied in time to adapt to a time varying channel impulse response.
Claim 6
Dependent Claim
26 words
An ARTEM system as recited in claim 4 wherein the predetermined number of taps is 63 and said taps are updated at substantially every 13.1 ms.
Claim 7
Dependent Claim
39 words
An ARTEM system as recited in claim 3 wherein said adaptive transversal equalizer comprises a delay line tapped at T second intervals each tap being coupled to a multiplier, each multiplier being in turn coupled to said summing means.
Claim 8
Dependent Claim
18 words
An ARTEM system as recited in claim 6 wherein said delay line comprises a digital serial shift register.
Claim 9
Dependent Claim
69 words
An ARTEM system as recited in claim 1 wherein said phase correction and carrier recovery means comprise frequency tracking means for tracking a frequency which corresponds to the centroid of the energy of multiple receiver carriers, phase estimator means coupled to said frequency tracking means for estimating correct phase of a modulated carrier with respect to a reference carrier, and phase corrector means for correcting the phase corrupted carrier.
Claim 10
Dependent Claim
102 words
A signal processor system for continuously monitoring and compensating for predetermined time variants of an HF media, telephone channels and localized subsystems comprising: a quadrature demodulator means for demodulating a received signal into in-phase and quadrature demodulated baseband signal components, adaptive matched filter means having 63 stages coupled to said quadrature demodulator said adaptive matched filters compensating for residual carrier phase inaccuracies, summing means coupled to said adaptive matched filter means for summing the in-phase and quadrature signal components, and adaptive transversal equalizer means having 65 stages coupled to said summing means said adaptive transversal equalizer means for controllably eliminating intersymbol interference.
Claim 11
Dependent Claim
102 words
A signal processor system for continuously monitoring and compensating for predetermined time variants of an HF media, telephone channels and localized subsystems comprising: a quadrature demodulator means for demodulating a received signal into in-phase and quadrature demodulated baseband signal components, adaptive matched filter means having 63 stages coupled to said quadrature demodulator said adaptive matched filters compensating for residual carrier phase inaccuracies, summing means coupled to said adaptive matched filter means for summing the in-phase and quadrature signal components, and adaptive transversal equalizer means having 65 stages coupled to said summing means said adaptive transversal equalizer means for controllably eliminating intersymbol interference.
Claim 12
Dependent Claim
35 words
A signal processor system as recited in claim 9 including low pass filter (LPF) means, coupled to said quadrature demodulator means and to said adaptive matched filter means, for low pass filtering the baseband signal.
Claim 13
Dependent Claim
34 words
A signal processor system as recited in claim 10 including analog-to-digital (A/D) converter means, coupled to said LPF means and said adaptive matched filter means, for converting the baseband signal to a digital signal.
Claim 14
Dependent Claim
32 words
A signal processor system as recited in claim 11 including first pseudo-noise (PN) filter means, coupled to said A/D converter and to said adaptive matched filter means, for filtering a PN signal.
Claim 15
Dependent Claim
40 words
A signal processor system as recited in claim 12 including first tap weight calculator means, coupled to said first PN filter means and to said adaptive matched filter means, for calculating tap weight values for said adaptive matched filter means.
Claim 16
Dependent Claim
25 words
A signal processor system as recited in claim 13 including second PN filter means, coupled to said transversal equalizer, for further filtering the PN signal.
Claim 17
Dependent Claim
54 words
A signal processor system as recited in claim 14 wherein said transversal equalizer means has a predetermined number of adjustable taps and including second tap weight calculator means, coupled to said second PN filter means and to said adaptive transversal equalizer means, for calculating the tap weight values for said adaptive transversal equalizer means.
Claim 18
Dependent Claim
37 words
A signal processor system as recited in claim 15 including automatic gain control AGC means, coupled to said quadrature demodulators and to said second PN filter means, for providing automatic gain adjustment to said signal processor system.
Claim 19
Dependent Claim
21 words
A signal processor system as recited in claim 15 including means for updating said adaptive filter means substantially every 13.1 milliseconds.
Claim 20
Independent Claim
69 words
A method of processing HF electronic signals to equalize an HF channel comprising the steps of: a. quadrature demodulating a passband signal to baseband quadrature component signals; b. low pass filtering the baseband signals through low pass filters (LPF''s); c. processing the low pass filtered baseband signals through adaptive matched filters; d. adding the adaptive match filtered baseband signals; and, e. equalizing the added signals to reduce intersymbol interference.
Claim 21
Independent Claim
69 words
A method of processing HF electronic signals to equalize an HF channel comprising the steps of: a. quadrature demodulating a passband signal to baseband quadrature component signals; b. low pass filtering the baseband signals through low pass filters (LPF''s); c. processing the low pass filtered baseband signals through adaptive matched filters; d. adding the adaptive match filtered baseband signals; and, e. equalizing the added signals to reduce intersymbol interference.
Claim 22
Dependent Claim
20 words
A method as recited in claim 18 including the step of updating the match filtered baseband signal every 13.1 milliseconds.
Claim 23
Dependent Claim
218 words
An automated real-time equalized modem (ARTEM) system employing multi-level pulse amplitude modulation-single side band (PAM-SSB) modulation and continuous real-time automatic channel measurement and equalization of time variants of propagation characteristics of the channel comprising: a. modulatiNg means for providing at least 15 level PAM-SSB modulation; b. pseudo-noise (PN) sequence generator means coupled to said modulation means said PN generator for generating PN signal sequences of predetermined length; c. transmitter means, coupled to said modulation means, for transmitting modulated signals; d. receiver means responsive to said transmitter means for receiving the transmitted signals, said receiver means further comprising: Alpha . signal processor for processing the received modulated signal, said signal processor means comprising: an in-phase demodulator means for demodulating the received signal, adaptive matched filter means coupled to said demodulator means and responsive to the PN signal sequence for compensating residual carrier phase inaccuracies, and adaptive transversal equalizer means coupled to said matched filter means having adjustable tap gains for controllably eliminating intersymbol interference; Beta . phase correction and carrier recovery means for correcting phase and recovering the received signal, said phase correction and carrier recovery means coupled to said signal processor means; and, gamma . data detect error correction means for converting a predetermined number of quantization levels to at least 15, and detecting and correcting decoding errors.
Claim 24
Dependent Claim
218 words
An automated real-time equalized modem (ARTEM) system employing multi-level pulse amplitude modulation-single side band (PAM-SSB) modulation and continuous real-time automatic channel measurement and equalization of time variants of propagation characteristics of the channel comprising: a. modulatiNg means for providing at least 15 level PAM-SSB modulation; b. pseudo-noise (PN) sequence generator means coupled to said modulation means said PN generator for generating PN signal sequences of predetermined length; c. transmitter means, coupled to said modulation means, for transmitting modulated signals; d. receiver means responsive to said transmitter means for receiving the transmitted signals, said receiver means further comprising: Alpha . signal processor for processing the received modulated signal, said signal processor means comprising: an in-phase demodulator means for demodulating the received signal, adaptive matched filter means coupled to said demodulator means and responsive to the PN signal sequence for compensating residual carrier phase inaccuracies, and adaptive transversal equalizer means coupled to said matched filter means having adjustable tap gains for controllably eliminating intersymbol interference; Beta . phase correction and carrier recovery means for correcting phase and recovering the received signal, said phase correction and carrier recovery means coupled to said signal processor means; and, gamma . data detect error correction means for converting a predetermined number of quantization levels to at least 15, and detecting and correcting decoding errors.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-03-04 | 1977-09-03 | 1978-03-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-03-04 | 1981-09-03 | 1982-03-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-03-04 | 1985-09-03 | 1986-03-05 | $7700.00 | Window Closed / Lapsed |