GB1410638A - Selection and processing system for signals including frequency discriminator - Google Patents

Selection and processing system for signals including frequency discriminator

Info

Publication number
GB1410638A
GB1410638A GB5648572A GB5648572A GB1410638A GB 1410638 A GB1410638 A GB 1410638A GB 5648572 A GB5648572 A GB 5648572A GB 5648572 A GB5648572 A GB 5648572A GB 1410638 A GB1410638 A GB 1410638A
Authority
GB
United Kingdom
Prior art keywords
frequency
filter
oscillator
signals
signal
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
Application number
GB5648572A
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.)
International Standard Electric Corp
Original Assignee
International Standard Electric Corp
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
Priority to DE19722253940 priority Critical patent/DE2253940A1/en
Application filed by International Standard Electric Corp filed Critical International Standard Electric Corp
Priority to GB5648572A priority patent/GB1410638A/en
Publication of GB1410638A publication Critical patent/GB1410638A/en
Expired legal-status Critical Current

Links

Classifications

    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03J—TUNING RESONANT CIRCUITS; SELECTING RESONANT CIRCUITS
    • H03J7/00—Automatic frequency control; Automatic scanning over a band of frequencies
    • H03J7/02—Automatic frequency control
    • H03J7/04—Automatic frequency control where the frequency control is accomplished by varying the electrical characteristics of a non-mechanically adjustable element or where the nature of the frequency controlling element is not significant
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S1/00—Beacons or beacon systems transmitting signals having a characteristic or characteristics capable of being detected by non-directional receivers and defining directions, positions, or position lines fixed relatively to the beacon transmitters; Receivers co-operating therewith
    • G01S1/02—Beacons or beacon systems transmitting signals having a characteristic or characteristics capable of being detected by non-directional receivers and defining directions, positions, or position lines fixed relatively to the beacon transmitters; Receivers co-operating therewith using radio waves
    • G01S1/08—Systems for determining direction or position line
    • G01S1/20—Systems for determining direction or position line using a comparison of transit time of synchronised signals transmitted from non-directional antennas or antenna systems spaced apart, i.e. path-difference systems
    • G01S1/24—Systems for determining direction or position line using a comparison of transit time of synchronised signals transmitted from non-directional antennas or antenna systems spaced apart, i.e. path-difference systems the synchronised signals being pulses or equivalent modulations on carrier waves and the transit times being compared by measuring the difference in arrival time of a significant part of the modulations, e.g. LORAN systems
    • G01S1/245—Details of receivers cooperating therewith, e.g. determining positive zero crossing of third cycle in LORAN-C
    • H—ELECTRICITY
    • H03—ELECTRONIC CIRCUITRY
    • H03D—DEMODULATION OR TRANSFERENCE OF MODULATION FROM ONE CARRIER TO ANOTHER
    • H03D3/00—Demodulation of angle-, frequency- or phase- modulated oscillations
    • H03D3/001—Details of arrangements applicable to more than one type of frequency demodulator
    • H03D3/002—Modifications of demodulators to reduce interference by undesired signals
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
    • H04B1/06—Receivers
    • H04B1/10—Means associated with receiver for limiting or suppressing noise or interference
    • H04B1/1027—Means associated with receiver for limiting or suppressing noise or interference assessing signal quality or detecting noise/interference for the received signal
    • H04B1/1036—Means associated with receiver for limiting or suppressing noise or interference assessing signal quality or detecting noise/interference for the received signal with automatic suppression of narrow band noise or interference, e.g. by using tuneable notch filters
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
    • H04B1/60—Supervising unattended repeaters
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
    • H04B1/06—Receivers
    • H04B1/10—Means associated with receiver for limiting or suppressing noise or interference
    • H04B1/1027—Means associated with receiver for limiting or suppressing noise or interference assessing signal quality or detecting noise/interference for the received signal
    • H04B2001/1063—Means associated with receiver for limiting or suppressing noise or interference assessing signal quality or detecting noise/interference for the received signal using a notch filter
    • H—ELECTRICITY
    • H04—ELECTRIC COMMUNICATION TECHNIQUE
    • H04B—TRANSMISSION
    • H04B1/00—Details of transmission systems, not covered by a single one of groups H04B3/00 - H04B13/00; Details of transmission systems not characterised by the medium used for transmission
    • H04B1/06—Receivers
    • H04B1/10—Means associated with receiver for limiting or suppressing noise or interference
    • H04B1/1027—Means associated with receiver for limiting or suppressing noise or interference assessing signal quality or detecting noise/interference for the received signal
    • H04B2001/1072—Means associated with receiver for limiting or suppressing noise or interference assessing signal quality or detecting noise/interference for the received signal by tuning the receiver frequency

Abstract

1410638 AFC systems; active filters; radio navigation INTERNATIONAL STANDARD ELECTRIC CORP 7 Dec 1972 56485/72 Headings H3A H3U and H4D A system comprises a source 3 of signals, e.g. Loran signals and interfering CW, FSK, on-off keying signals within a given frequency band, an oscillator 7, signal selection circuitry 1 for selecting the strongest input signal having a predetermined large duty cycle, a frequency discriminator 6 responsive to the selected signal for varying the oscillator frequency so that it bears a predetermined relationship to that of the selected signal, a frequency converter 33 coupled to the source and the oscillator for shifting the selected signal frequency to lie within the operational band of a signal processor 34, e.g. a notch filter. The system is designed to remove strong interference signals having a duty cycle larger than that of the desired signals by automatically shifting the former to the attenuation band of a notch filter. The signal selection circuitry 1 includes an AGC-pulse reducer circuit 8-11 which passes only the strongest interference signal to a frequency discriminator 6. The discriminator includes a gated phase detector 26 to which signals are applied via two paths 12, 13. The path 13 includes up, down converters 14, 23 controlled by the oscillator 7, a search, lock-on band-pass circuitry 15-22, a limiter and differentiator 25. The path 12 includes a filter 28 providing a phase delay same as that encountered in path 13 and an amplifier 29 whose gain is adjustable to ensure stable operation. In the gated phase detector, 26, signals arriving via .path 12 are gated by pulses derived in the path 13 (and differing in phase substantially, by 180 degrees to provide an output whose amplitude is dependent on the relative phase difference as well as, the input frequency. The phase detector output is integrated at 31 to control the oscillator 7. In the event of input signal failure, the phase detector output is open circuited and the oscillator frequency is maintained at its final value. When the oscillator 7 is swept to its desired frequency, both filters 15, 16 are effective and as lock-on is achieved, the filter 15 is disconnected and only the filter 15 in its second narrower band is effective. In the signal processing circuitry 2, the filter 36 provides an equalizing phase shift for the notch filter 34. The filter 15, 16 (Fig. 3, not shown) may be a 3 pole filter, crystal filter respectively. In the alternative embodiment of Fig. 5 (not shown) only up-converters are provided and the follow-up circuitry operates at the higher frequency.
GB5648572A 1972-11-03 1972-12-07 Selection and processing system for signals including frequency discriminator Expired GB1410638A (en)

Priority Applications (2)

Application Number Priority Date Filing Date Title
DE19722253940 DE2253940A1 (en) 1972-11-03 1972-11-03 DEVICE FOR SUPPRESSING AN INTERFERENCE SIGNAL IN A BROADBAND RADIO SIGNAL
GB5648572A GB1410638A (en) 1972-11-03 1972-12-07 Selection and processing system for signals including frequency discriminator

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE19722253940 DE2253940A1 (en) 1972-11-03 1972-11-03 DEVICE FOR SUPPRESSING AN INTERFERENCE SIGNAL IN A BROADBAND RADIO SIGNAL
GB5648572A GB1410638A (en) 1972-11-03 1972-12-07 Selection and processing system for signals including frequency discriminator

Publications (1)

Publication Number Publication Date
GB1410638A true GB1410638A (en) 1975-10-22

Family

ID=25764046

Family Applications (1)

Application Number Title Priority Date Filing Date
GB5648572A Expired GB1410638A (en) 1972-11-03 1972-12-07 Selection and processing system for signals including frequency discriminator

Country Status (2)

Country Link
DE (1) DE2253940A1 (en)
GB (1) GB1410638A (en)

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1976129A1 (en) * 2007-03-26 2008-10-01 U-Blox-AG A method of processing a digital signal derived from an analog input signal of a GNSS receiver, a GNSS receiver base band circuit for carrying out the method and a GNSS receiver

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP1976129A1 (en) * 2007-03-26 2008-10-01 U-Blox-AG A method of processing a digital signal derived from an analog input signal of a GNSS receiver, a GNSS receiver base band circuit for carrying out the method and a GNSS receiver
US10033418B2 (en) 2007-03-26 2018-07-24 U-Blox Ag Method of processing a digital signal derived from an analog input signal of a GNSS receiver, a GNSS receiver base band circuit for carrying out the method and a GNSS receiver
US10236923B2 (en) 2007-03-26 2019-03-19 U-Blox Ag Method of processing a digital signal derived from an analog input signal of a GNSS receiver, a GNSS receiver base band circuit for carrying out the method and a GNSS receiver

Also Published As

Publication number Publication date
DE2253940A1 (en) 1974-05-09

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Legal Events

Date Code Title Description
PS Patent sealed
PLNP Patent lapsed through nonpayment of renewal fees