CA1322037C - Airborne receiver in microwave landing system with channel selection means by manual input of familiar abbreviations of airports - Google Patents
Airborne receiver in microwave landing system with channel selection means by manual input of familiar abbreviations of airportsInfo
- Publication number
- CA1322037C CA1322037C CA000579625A CA579625A CA1322037C CA 1322037 C CA1322037 C CA 1322037C CA 000579625 A CA000579625 A CA 000579625A CA 579625 A CA579625 A CA 579625A CA 1322037 C CA1322037 C CA 1322037C
- Authority
- CA
- Canada
- Prior art keywords
- mls
- signal
- frequency
- channel
- channel selection
- 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 - Fee Related
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Classifications
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03J—TUNING RESONANT CIRCUITS; SELECTING RESONANT CIRCUITS
- H03J5/00—Discontinuous tuning; Selecting predetermined frequencies; Selecting frequency bands with or without continuous tuning in one or more of the bands, e.g. push-button tuning, turret tuner
- H03J5/02—Discontinuous tuning; Selecting predetermined frequencies; Selecting frequency bands with or without continuous tuning in one or more of the bands, e.g. push-button tuning, turret tuner with variable tuning element having a number of predetermined settings and adjustable to a desired one of these settings
- H03J5/0245—Discontinuous tuning using an electrical variable impedance element, e.g. a voltage variable reactive diode, in which no corresponding analogue value either exists or is preset, i.e. the tuning information is only available in a digital form
- H03J5/0272—Discontinuous tuning using an electrical variable impedance element, e.g. a voltage variable reactive diode, in which no corresponding analogue value either exists or is preset, i.e. the tuning information is only available in a digital form the digital values being used to preset a counter or a frequency divider in a phase locked loop, e.g. frequency synthesizer
- H03J5/0281—Discontinuous tuning using an electrical variable impedance element, e.g. a voltage variable reactive diode, in which no corresponding analogue value either exists or is preset, i.e. the tuning information is only available in a digital form the digital values being used to preset a counter or a frequency divider in a phase locked loop, e.g. frequency synthesizer the digital values being held in an auxiliary non erasable memory
-
- 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
- G01S1/04—Details
- G01S1/045—Receivers
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- Engineering & Computer Science (AREA)
- Computer Networks & Wireless Communication (AREA)
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Radar, Positioning & Navigation (AREA)
- Remote Sensing (AREA)
- Computer Hardware Design (AREA)
- Microelectronics & Electronic Packaging (AREA)
- Circuits Of Receivers In General (AREA)
- Channel Selection Circuits, Automatic Tuning Circuits (AREA)
- Traffic Control Systems (AREA)
Abstract
Abstract of the Disclosure In a microwave landing system (MLS), an airborne MLS receiver has a channel selector for selecting an MLS
channel of a destination airport. In order to simplify operation of a channel selection dial by a pilot, the MLS receiver is provided with a keyboard for enabling to input airport name abbreviations which are familiar to and readily remembered by the pilot. A storage unit memorizes a table of the abbreviations and selection codes corresponding to the airports. The storage unit reads a particular selection code corresponding to a particular abbreviation of a destination airport input by the keyboard. A control circuit is responsive to the particular selection code and controls the channel selector to select the MLS channel of the destination airport. Alphabetic MLS station codes of airports may be used in place of the airport name abbreviations.
channel of a destination airport. In order to simplify operation of a channel selection dial by a pilot, the MLS receiver is provided with a keyboard for enabling to input airport name abbreviations which are familiar to and readily remembered by the pilot. A storage unit memorizes a table of the abbreviations and selection codes corresponding to the airports. The storage unit reads a particular selection code corresponding to a particular abbreviation of a destination airport input by the keyboard. A control circuit is responsive to the particular selection code and controls the channel selector to select the MLS channel of the destination airport. Alphabetic MLS station codes of airports may be used in place of the airport name abbreviations.
Description
~ 1 AIRBORNE RECEIVER IN MICROWAVE LANDING SYSTEM
WITH CHANNEL SELECTION MEANS BY MANUAL INPUT
j OF FAMILIAR ABBREVIATIONS OF AIRPORTS
Backaround of the Invention 1) Field of the Invention The present invention relates to a microwave landing system (MLS) and, in particular, to an airborne receiver for use in the MLS.
WITH CHANNEL SELECTION MEANS BY MANUAL INPUT
j OF FAMILIAR ABBREVIATIONS OF AIRPORTS
Backaround of the Invention 1) Field of the Invention The present invention relates to a microwave landing system (MLS) and, in particular, to an airborne receiver for use in the MLS.
2) Description of the Prior Art As a standard of a landing system for guiding an aircraft onto a runway with safety, the instrument landing system (ILS) has been used for a long time. Recently, the 15~ MLS has been~proposed as one which will take the place of the conventional ILS, and used for practical tests.
Reference is made to "MLS is OPERATIONAL" by W. C. REED, August 1984, Allied Bendix Aerospace (Reference 1) and "Introduction to MLS", October, 1987 by United States Department of Transportation Federal Aviation ;Administration Program Engineering and Maintenance Service (Reference 2).
... .
13220~7 The MLS comprises MLS ~round stations injtalled at airports and airborne receiver~ carried on aircraft, The M~S ground stations transmit MLS signals of frequency bands or channels individually assigned 5 thereto. The frequency band o~ 5031 ~ 5090.7 MHz and 20Q channels ~f channel Nos. 500 to 699 are provided to be a-qsigned to individual MLS ground ~tations o~
airports. When an aircraPt approaches a destinat~on airport, the aircraft receives a particular MLS channel 10 signal from the MLS ground station of the destination airport by its air~orne receiver which is called "MLS
receiver" so as to kn~w the azimuth, the elevation and distan~e to the destination airport.
The MLS receiver comprise.q a ~uning circuit or a lS channel selection circuit and a tuning dial or a channel selection dial in order to selectively receive a desired one of the individual MLS channel signals. In a conventional MLS receiver, the channel selection circuit is a ~uperheterodyne type which comprises a local 2~ oscillator of a frequency synthesi~er type and a mixer.
The oscillating frequency of th~ local oscillator is adjuste~ by the channel selection dial. When the alrcraft approaohes the destination airport, an operator or a pilot of the aircraft must manually operate the ~: 25 channel selection dial of the MLS receiver to ~elect the particular MLS channel of the MLS ground station of the destination airport. As a result, the channel ~elect~on circuit i8 adjusted to tune the MLS rec~i~er to the l322n37 particular MLS channel to thereby receive the particular MLS channel signal. More in detail, the local oscillator is adjusted by the manual operation of the channel selection dial to produce a particular local signal of a particular local frequency which is applied to the mixer.
The mixer combines the particular local signal with the particular MLS channel signal to frequency convert the particular MLS signal to an intermediate frequency (IF) signal of a fixed IF frequency. Thus, the MLS receiver is tuned to the particular MLS channel and the particular MLS
channel signal is obtained as the IF signal from the channel selection circuit.
However, since it is difficult for the pilot to remember the channel numbers and/or transmitting frequencies of the MLS ground stations of all of the airports, he must use a list of the channel numbers and names of the airports prior to operation on the channel selection dial. It is complicated for the pilot to refer to the list.
Summary of the Invent ion According to the present invention, an airborne MLS
receiver is provided wherein the MLS channel selecting operation of the destination airport can readily be ; performed without use of the list.
According to the present invention, an airborne MLS
receiver is provided wherein the channel selection can readily be performed by setting an abbreviation of airport name of or a station code of an MLS ground station of a destination airport to the receiver which is familiar to the pilot.
An airborne MLS (Microwave Landing System) receiver for use in an MLS environment, according to the present invention, comprises input means for directly manually inputting one of a number of different character abbreviations of destination airports wherein the abbreviations are commonl~ known by pilots operating the receiver; storage means for memorizing a table of channel : .selection codes of MLS channel numbers assigned to respective MLS ground stations at different airports together with corresponding character abbreviations of the airports, the storage means being coupled to the input means and responslve to the input character abbreviations, and means for reading a particular one of said channel selection codes of MLS channel numbers corresponding to an input character abbreviation from the table; and a channel selection circuit for selecting a desired MLS channel for reception of corresponding MLS channel signals from a particular ground station at a destination airport, comprising a control circuit coupled to the storage means and responsive to the particular channel selection code ; ~read from the table, for enabling selection of the desired : :~25 MLS channel and reception of the corresponding MLS channel ~signals.
13220~7 According to a preferred aspect of the invention, the channel selection circuit of the MLS receiver comprises a local oscillator of a variable frequency type for oscillating a local signal of a controlled frequency and a mixer circuit for mixing a specific one of the MLS channel signals and the local signal to convert the specific MLS
channel signal to an intermediate frequency (IF) signal of a fixed IF frequency and to receive the specific MLS
channel signal, wherein the control means is responsive to the particular channel selection code and controls the local oscillator to generate the local signal having a particular frequency as the controlled frequency, the particular frequency being equal to a particular difference frequency between the specific MLS channel signal and the IF signal, wherein the mixer circuit converts the specific MLS channel signal to the IF signal.
According to still another aspect, the input means is a conventional alphabetic keyboard.
Brief Descri~tion of the Dra~in~s Fig. 1 is a block diagram view of a main part of an MLS receiver according to an embodiment of the present invention;
Fig. 2 is a table of airport abbreviations and channel selection codes memorized in a storage means; and , Fig. 3 i6 a block diagram view of an example of a local o~cillator.
Descrlption of the Preferred Embodiment Referring to Fig . 1, the MLS receiver ~hown 5 therein comprises a radio frequency (R~) bandp~
filter ~BPF) 11 for filtering the MLS frequency band signal from an incoming si~nal through an antenns 10.
The MLS freguency band signal is applied to a channel ~election circuit 12. In the pxesent embo~i~ent, the 10 channel ~election cirouit 12 i6 the 6uperheterodyne type and comprise~ a local oscillator 13 and a mixes : 14.
~ n the prior art, a channel selection dtal i6 provided to ad;ust an oscillating ~requency o~ the 15 looal oscillator 13 to:select a desired on~ of the MLS
channelc, and the desired MLS channel signal i~
- obtained a8 the IF ~ignal ~rom the channel selection ~ .
~ . ¢ir¢uit 12, as de~cribed in the preamble.
:: : The IF signal is amplified at an IF ampli~ier 20 ~AMP) 15 apd is therea~ter prooessed at a proo~Jsing circuit ~not ahown) which ~ known in the prior art.
he ML8 reoeiver acoording to the present . ~ embodiment comprises an input unit 16 and a storage u~it 17 in place of the channel selection dlal.
The input unit 16 i~ a key~oardr for example, a conventional alpbabetic keyboard ~or inputting an : abbreviation of an airpcrt name or a keyboard oomprising a plurality o~ keys correqponding to 1322~37 airports with identification of the airport name abbreviations.
The storage unit 17 previously memorizes a table of abbreviations of airport names and channel selection codes for selecting MLS channels of the corresponding airports, as shown in Fig. 2.
Now, operation of the storage unit 17 will be described in connection with, for example, the Wexford County Airport in Cadillac City, Michigan, U.S.A. The airport has an abbreviation of ~CAD~.
Referring to Fig. 2, the abbreviation ~CAD" is shown in an abbreviation section in a table of Fig. 2. A
corresponding code "m(602)~ is a channel selection code for selecting the MLS channel (No. 602) of the MLS ground station of the Wexford County Airport.
The storage unit 17 responds to an airport name abbreviation from the input unit 16 and converts it to a corresponding one of the channel selection codes which is applied to a control circuit 18 in the local oscillator 13.
The control circuit 18 is responsive to the corresponding channel selection code and controls the local oscillator 13 to produce a particular local signal of a particular local frequency which is applied to the mixer 14. The mixer 14 combines the particular local signal with a particular MLS
channel signal to convert the particular MLS signal to an IF signal, in the similar manner as the ,:
,,~
~'~
' ~32~0~7 conventional channel selection circuit of ~
~uperheterodyne type as described in the pre~mble.
Now, it is asjumed that the MLS receiver has the fixed IF requency of 160~8 MHz. When the S abbrevistion "CAD" of the airport is set at the input unit 16, the stora~e unit 17 applles the corresponding channel selection code "m(602)" to the control clrcuit 1~. The channel number o the airport i8 602 which i5 corr~ponding to a frequency of 5061.6 MHz. In order 10 to receive the MLS ~ignal of 5061.6 M~, the local oscillating frequency in.the receiver is set at 4900.8 M~z which is equal to (5061.6 M~z - 160.8 MHz).
Therefore, the control c$rcuit 18 controls the l~cal osclllator 13 to produce a particular local 6i-gnal 15 ~hich has a ~requency of 4900.8 NHz. The particular local cignal of 4900.8 MRz is applied to the mixer 14, from which the ~L~ chan~el 5ig~al ~rom the ~CAD"
airport is obtained as the I~ signal. ~he IF signal is ~pplied to the IF amplifier 15.
Re~erring to Fig. 3, the local oscillator 13 may be a frea~uenoy synthesizer which comprl~es a fixed ~re~uency oQcillator 19 for o~cillat~ng an 06aillating signal of a fixed ~requency of, for exa~ple, 10 M~z, a counter or fixed frequency divider 20 or frequency 25 dlviding the osciliating signal at a fixed d~viding ratio of l/M (M = 200) to produce a divided signal, a phase locked loop, and a multiplier 21 with a multiplyinq ratio of, for ~xample, 6.
1322~37 I
The PLL comprises a voltage controlled oscillator ~VCo) 22 ~or oscillating a VC0 signal, a variable frequency di~ider 18' as the con~rol circuit for frequency dividinq the vco signal at a dividing 5 ratio set thereat to produce a ~ariahle frequency divided signal, a phase detector 23 or comparing the divided signal and the trariab~ e frequency divided signal to detect a phase difference therebetween as an ¦ error signal, and a loop ~ilter 24 for re~oving a high 10 frequency signal component to derive the erxor signal which i~ applied to the VC0 22 so as to stabili~e a frequency of the VC0 signal.
~ he variable frequency divider 18' i9 a pro~rammable counter to which a variable dividing ratio 15 is Qet as the channel sele~tion codes by the ~torage , unit 17. In re~pon~e to input of an airpor~ name ; abbreviation at the input unit 16, a corresponding dividing ratio i~ delivered ~rom the storage unit 17 to set it in the frequency divider 18'. The dividing 20 r~tio is applied to the frequency divider 18' from the storage unit 17 to control a frequency of the VC0 signal~ Then, the VCO signal is fr~quency multiplied by 6 at the multiplier 21 to produce the local ~ignal.
In this aonne~tion, th~ dividing ratio~ as the 25 channel selection codes are previou~ly determined with refer~nce to the fixed frequency of the fixed frequency : oscillator 19, the ~LS chann~ls, the IF frequency, ~' 1 1 . ' : .
i,~,,.,~
dividlng ratio, and the multiplying ratio, as shown in the following table.
TABEE
Channel ~umber S00 ¦ 602 .
5 Frequency ~MHz) 5031 ~ 5061.6 5090.7 _ Fixed Freq~enoy (MHz) 10 ~ixed Dividing Ratio ~Mj 200 Varl ble Dividing _ 16Z34 ¦16336 ~16433 VCO Frequency ~MHz) 811.7 ¦ 816.B ¦ 821.65 10 Multiplying Ratio 6 Controlled Frequency 4~70.2 ¦ 4900.8 ~ 29.9 _ IF Frequency (MHz) 160.8 Alrport name abbreviations are used in the above-mentioned embodiment, but alphabetic station 15 codes of the MLS ground station6 of the airports, whioh are ~a~iliar to pilots, can be us~d in plac~ of the airport name abbreviations. For in tanoe, the MLS
ground statlon at the "CAD~ airport has an alphabetic station code "MAJ~ herefore, ~MAJE" is described 20 ad~acent "CAD" but with a parenthe~is in the ta~le o~
Pig. ~.
~(
Reference is made to "MLS is OPERATIONAL" by W. C. REED, August 1984, Allied Bendix Aerospace (Reference 1) and "Introduction to MLS", October, 1987 by United States Department of Transportation Federal Aviation ;Administration Program Engineering and Maintenance Service (Reference 2).
... .
13220~7 The MLS comprises MLS ~round stations injtalled at airports and airborne receiver~ carried on aircraft, The M~S ground stations transmit MLS signals of frequency bands or channels individually assigned 5 thereto. The frequency band o~ 5031 ~ 5090.7 MHz and 20Q channels ~f channel Nos. 500 to 699 are provided to be a-qsigned to individual MLS ground ~tations o~
airports. When an aircraPt approaches a destinat~on airport, the aircraft receives a particular MLS channel 10 signal from the MLS ground station of the destination airport by its air~orne receiver which is called "MLS
receiver" so as to kn~w the azimuth, the elevation and distan~e to the destination airport.
The MLS receiver comprise.q a ~uning circuit or a lS channel selection circuit and a tuning dial or a channel selection dial in order to selectively receive a desired one of the individual MLS channel signals. In a conventional MLS receiver, the channel selection circuit is a ~uperheterodyne type which comprises a local 2~ oscillator of a frequency synthesi~er type and a mixer.
The oscillating frequency of th~ local oscillator is adjuste~ by the channel selection dial. When the alrcraft approaohes the destination airport, an operator or a pilot of the aircraft must manually operate the ~: 25 channel selection dial of the MLS receiver to ~elect the particular MLS channel of the MLS ground station of the destination airport. As a result, the channel ~elect~on circuit i8 adjusted to tune the MLS rec~i~er to the l322n37 particular MLS channel to thereby receive the particular MLS channel signal. More in detail, the local oscillator is adjusted by the manual operation of the channel selection dial to produce a particular local signal of a particular local frequency which is applied to the mixer.
The mixer combines the particular local signal with the particular MLS channel signal to frequency convert the particular MLS signal to an intermediate frequency (IF) signal of a fixed IF frequency. Thus, the MLS receiver is tuned to the particular MLS channel and the particular MLS
channel signal is obtained as the IF signal from the channel selection circuit.
However, since it is difficult for the pilot to remember the channel numbers and/or transmitting frequencies of the MLS ground stations of all of the airports, he must use a list of the channel numbers and names of the airports prior to operation on the channel selection dial. It is complicated for the pilot to refer to the list.
Summary of the Invent ion According to the present invention, an airborne MLS
receiver is provided wherein the MLS channel selecting operation of the destination airport can readily be ; performed without use of the list.
According to the present invention, an airborne MLS
receiver is provided wherein the channel selection can readily be performed by setting an abbreviation of airport name of or a station code of an MLS ground station of a destination airport to the receiver which is familiar to the pilot.
An airborne MLS (Microwave Landing System) receiver for use in an MLS environment, according to the present invention, comprises input means for directly manually inputting one of a number of different character abbreviations of destination airports wherein the abbreviations are commonl~ known by pilots operating the receiver; storage means for memorizing a table of channel : .selection codes of MLS channel numbers assigned to respective MLS ground stations at different airports together with corresponding character abbreviations of the airports, the storage means being coupled to the input means and responslve to the input character abbreviations, and means for reading a particular one of said channel selection codes of MLS channel numbers corresponding to an input character abbreviation from the table; and a channel selection circuit for selecting a desired MLS channel for reception of corresponding MLS channel signals from a particular ground station at a destination airport, comprising a control circuit coupled to the storage means and responsive to the particular channel selection code ; ~read from the table, for enabling selection of the desired : :~25 MLS channel and reception of the corresponding MLS channel ~signals.
13220~7 According to a preferred aspect of the invention, the channel selection circuit of the MLS receiver comprises a local oscillator of a variable frequency type for oscillating a local signal of a controlled frequency and a mixer circuit for mixing a specific one of the MLS channel signals and the local signal to convert the specific MLS
channel signal to an intermediate frequency (IF) signal of a fixed IF frequency and to receive the specific MLS
channel signal, wherein the control means is responsive to the particular channel selection code and controls the local oscillator to generate the local signal having a particular frequency as the controlled frequency, the particular frequency being equal to a particular difference frequency between the specific MLS channel signal and the IF signal, wherein the mixer circuit converts the specific MLS channel signal to the IF signal.
According to still another aspect, the input means is a conventional alphabetic keyboard.
Brief Descri~tion of the Dra~in~s Fig. 1 is a block diagram view of a main part of an MLS receiver according to an embodiment of the present invention;
Fig. 2 is a table of airport abbreviations and channel selection codes memorized in a storage means; and , Fig. 3 i6 a block diagram view of an example of a local o~cillator.
Descrlption of the Preferred Embodiment Referring to Fig . 1, the MLS receiver ~hown 5 therein comprises a radio frequency (R~) bandp~
filter ~BPF) 11 for filtering the MLS frequency band signal from an incoming si~nal through an antenns 10.
The MLS freguency band signal is applied to a channel ~election circuit 12. In the pxesent embo~i~ent, the 10 channel ~election cirouit 12 i6 the 6uperheterodyne type and comprise~ a local oscillator 13 and a mixes : 14.
~ n the prior art, a channel selection dtal i6 provided to ad;ust an oscillating ~requency o~ the 15 looal oscillator 13 to:select a desired on~ of the MLS
channelc, and the desired MLS channel signal i~
- obtained a8 the IF ~ignal ~rom the channel selection ~ .
~ . ¢ir¢uit 12, as de~cribed in the preamble.
:: : The IF signal is amplified at an IF ampli~ier 20 ~AMP) 15 apd is therea~ter prooessed at a proo~Jsing circuit ~not ahown) which ~ known in the prior art.
he ML8 reoeiver acoording to the present . ~ embodiment comprises an input unit 16 and a storage u~it 17 in place of the channel selection dlal.
The input unit 16 i~ a key~oardr for example, a conventional alpbabetic keyboard ~or inputting an : abbreviation of an airpcrt name or a keyboard oomprising a plurality o~ keys correqponding to 1322~37 airports with identification of the airport name abbreviations.
The storage unit 17 previously memorizes a table of abbreviations of airport names and channel selection codes for selecting MLS channels of the corresponding airports, as shown in Fig. 2.
Now, operation of the storage unit 17 will be described in connection with, for example, the Wexford County Airport in Cadillac City, Michigan, U.S.A. The airport has an abbreviation of ~CAD~.
Referring to Fig. 2, the abbreviation ~CAD" is shown in an abbreviation section in a table of Fig. 2. A
corresponding code "m(602)~ is a channel selection code for selecting the MLS channel (No. 602) of the MLS ground station of the Wexford County Airport.
The storage unit 17 responds to an airport name abbreviation from the input unit 16 and converts it to a corresponding one of the channel selection codes which is applied to a control circuit 18 in the local oscillator 13.
The control circuit 18 is responsive to the corresponding channel selection code and controls the local oscillator 13 to produce a particular local signal of a particular local frequency which is applied to the mixer 14. The mixer 14 combines the particular local signal with a particular MLS
channel signal to convert the particular MLS signal to an IF signal, in the similar manner as the ,:
,,~
~'~
' ~32~0~7 conventional channel selection circuit of ~
~uperheterodyne type as described in the pre~mble.
Now, it is asjumed that the MLS receiver has the fixed IF requency of 160~8 MHz. When the S abbrevistion "CAD" of the airport is set at the input unit 16, the stora~e unit 17 applles the corresponding channel selection code "m(602)" to the control clrcuit 1~. The channel number o the airport i8 602 which i5 corr~ponding to a frequency of 5061.6 MHz. In order 10 to receive the MLS ~ignal of 5061.6 M~, the local oscillating frequency in.the receiver is set at 4900.8 M~z which is equal to (5061.6 M~z - 160.8 MHz).
Therefore, the control c$rcuit 18 controls the l~cal osclllator 13 to produce a particular local 6i-gnal 15 ~hich has a ~requency of 4900.8 NHz. The particular local cignal of 4900.8 MRz is applied to the mixer 14, from which the ~L~ chan~el 5ig~al ~rom the ~CAD"
airport is obtained as the I~ signal. ~he IF signal is ~pplied to the IF amplifier 15.
Re~erring to Fig. 3, the local oscillator 13 may be a frea~uenoy synthesizer which comprl~es a fixed ~re~uency oQcillator 19 for o~cillat~ng an 06aillating signal of a fixed ~requency of, for exa~ple, 10 M~z, a counter or fixed frequency divider 20 or frequency 25 dlviding the osciliating signal at a fixed d~viding ratio of l/M (M = 200) to produce a divided signal, a phase locked loop, and a multiplier 21 with a multiplyinq ratio of, for ~xample, 6.
1322~37 I
The PLL comprises a voltage controlled oscillator ~VCo) 22 ~or oscillating a VC0 signal, a variable frequency di~ider 18' as the con~rol circuit for frequency dividinq the vco signal at a dividing 5 ratio set thereat to produce a ~ariahle frequency divided signal, a phase detector 23 or comparing the divided signal and the trariab~ e frequency divided signal to detect a phase difference therebetween as an ¦ error signal, and a loop ~ilter 24 for re~oving a high 10 frequency signal component to derive the erxor signal which i~ applied to the VC0 22 so as to stabili~e a frequency of the VC0 signal.
~ he variable frequency divider 18' i9 a pro~rammable counter to which a variable dividing ratio 15 is Qet as the channel sele~tion codes by the ~torage , unit 17. In re~pon~e to input of an airpor~ name ; abbreviation at the input unit 16, a corresponding dividing ratio i~ delivered ~rom the storage unit 17 to set it in the frequency divider 18'. The dividing 20 r~tio is applied to the frequency divider 18' from the storage unit 17 to control a frequency of the VC0 signal~ Then, the VCO signal is fr~quency multiplied by 6 at the multiplier 21 to produce the local ~ignal.
In this aonne~tion, th~ dividing ratio~ as the 25 channel selection codes are previou~ly determined with refer~nce to the fixed frequency of the fixed frequency : oscillator 19, the ~LS chann~ls, the IF frequency, ~' 1 1 . ' : .
i,~,,.,~
dividlng ratio, and the multiplying ratio, as shown in the following table.
TABEE
Channel ~umber S00 ¦ 602 .
5 Frequency ~MHz) 5031 ~ 5061.6 5090.7 _ Fixed Freq~enoy (MHz) 10 ~ixed Dividing Ratio ~Mj 200 Varl ble Dividing _ 16Z34 ¦16336 ~16433 VCO Frequency ~MHz) 811.7 ¦ 816.B ¦ 821.65 10 Multiplying Ratio 6 Controlled Frequency 4~70.2 ¦ 4900.8 ~ 29.9 _ IF Frequency (MHz) 160.8 Alrport name abbreviations are used in the above-mentioned embodiment, but alphabetic station 15 codes of the MLS ground station6 of the airports, whioh are ~a~iliar to pilots, can be us~d in plac~ of the airport name abbreviations. For in tanoe, the MLS
ground statlon at the "CAD~ airport has an alphabetic station code "MAJ~ herefore, ~MAJE" is described 20 ad~acent "CAD" but with a parenthe~is in the ta~le o~
Pig. ~.
~(
Claims (6)
1. An airborne MLS (Microwave Landing System) receiver for use in an MLS environment, comprising a channel selection circuit for selecting a particular one of MLS
channels of MLS signals from MLS ground stations installed at airports having abbreviations familiar to pilots, wherein the improvements comprising:
input means for directly manually inputting one of a number of different character abbreviations of destination airports wherein said abbreviations are commonly known by pilots operating the receiver;
storage means for memorizing a table of channel selection codes of MLS channel numbers assigned to respective MLS ground stations at different airports together with corresponding character abbreviations of the airports, said storage means being coupled to said input means and responsive to the input character abbreviations, and means for reading a particular one of said channel selection codes of MLS channel numbers corresponding to an input character abbreviation from said table; and a channel selection circuit for selecting a desired MLS channel for reception of corresponding MLS channel signals from a particular ground station at a destination airport, comprising a control circuit coupled to said storage means and responsive to said particular channel selection code read from said table, for enabling selection of the desired MLS channel and reception of the corresponding MLS channel signals.
channels of MLS signals from MLS ground stations installed at airports having abbreviations familiar to pilots, wherein the improvements comprising:
input means for directly manually inputting one of a number of different character abbreviations of destination airports wherein said abbreviations are commonly known by pilots operating the receiver;
storage means for memorizing a table of channel selection codes of MLS channel numbers assigned to respective MLS ground stations at different airports together with corresponding character abbreviations of the airports, said storage means being coupled to said input means and responsive to the input character abbreviations, and means for reading a particular one of said channel selection codes of MLS channel numbers corresponding to an input character abbreviation from said table; and a channel selection circuit for selecting a desired MLS channel for reception of corresponding MLS channel signals from a particular ground station at a destination airport, comprising a control circuit coupled to said storage means and responsive to said particular channel selection code read from said table, for enabling selection of the desired MLS channel and reception of the corresponding MLS channel signals.
2. An airborne MLS receiver as claimed in Claim 1, said channel selection circuit comprising a local oscillator of a variable frequency type for oscillating a local signal of a controlled frequency and a mixer circuit for mixing a specific one of the MLS channel signals and said local signal to convert said specific MLS channel signal to an intermediate frequency (IF) signal of a fixed IF frequency and to receive said specific MLS channel signal, wherein said control means is responsive to said particular channel selection code and controls said local oscillator to generate said local signal having a particular frequency as the controlled frequency, said particular frequency being equal to a particular difference frequency between said specific MLS channel signal and said IF signal, wherein said mixer circuit converts said specific MLS channel signal to the IF signal.
3. An airborne MLS receiver as claimed in Claim 2, wherein said local oscillator is a frequency synthesizer having a variable frequency divider, said control circuit including said variable frequency divider.
4. An airborne MLS receiver as claimed in Claim 3, wherein said frequency synthesizer comprises a fixed frequency oscillator for oscillating an oscillating signal of a fixed frequency, a fixed frequency divider for frequency dividing said oscillating signal at a fixed dividing ratio to produce a divided signal, a voltage controlled oscillator (VCO) for oscillating a VCO signal, said variable frequency divider as said control circuit including means for frequency dividing said VCO signal at a variable dividing ratio selected by said storage unit as said channel selection code to produce a variable frequency divided signal, a phase detector for comparing said divided signal and said variable frequency divided signal to detect a phase difference therebetween as an error signal, a loop filter for removing a high frequency signal component to deliver said error signal to said voltage controlled oscillator so as to control a frequency of said VCO signal, and a frequency multiplier for multiplying said VCO signal by a multiplying ratio to produce a multiplied signals as said local signal, said variable dividing ratio as said channel selection code being previously determined with reference to the fixed frequency of said fixed frequency oscillator, said MLS channel, said IF frequency, the fixed dividing ratio, and the multiplying ratio.
5. An airborne MLS receiver as claimed in Claim 1, wherein said character abbreviations are alphabetic station codes assigned to said MLS ground stations installed at the airports.
6. An airborne MLS receiver as claimed in Claim 1, wherein said input means is an alphabetic keyboard.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP25573687A JPH0198100A (en) | 1987-10-09 | 1987-10-09 | Mls receiver |
| JP255,736/1987 | 1987-10-09 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1322037C true CA1322037C (en) | 1993-09-07 |
Family
ID=17282917
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000579625A Expired - Fee Related CA1322037C (en) | 1987-10-09 | 1988-10-07 | Airborne receiver in microwave landing system with channel selection means by manual input of familiar abbreviations of airports |
Country Status (4)
| Country | Link |
|---|---|
| JP (1) | JPH0198100A (en) |
| CA (1) | CA1322037C (en) |
| FR (1) | FR2621703B1 (en) |
| GB (1) | GB2211041B (en) |
Families Citing this family (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7609204B2 (en) | 2005-08-30 | 2009-10-27 | Honeywell International Inc. | System and method for dynamically estimating output variances for carrier-smoothing filters |
| CN108778930A (en) * | 2017-09-30 | 2018-11-09 | 深圳市大疆创新科技有限公司 | Aircraft security guard method, equipment, aircraft and UAV system |
Family Cites Families (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| SE322277B (en) * | 1968-03-07 | 1970-04-06 | Aga Ab | |
| IT1047373B (en) * | 1975-10-16 | 1980-09-10 | Indesit | ARRANGEMENT FOR SELECTING A RECEIVABLE FREQUENCY IN A SIGNAL RECEIVER |
| US4122395A (en) * | 1976-05-10 | 1978-10-24 | Draco Laboratories, Inc. | Radio control circuit with microprocessor |
| GB2064905B (en) * | 1979-11-30 | 1983-10-05 | Smiths Industries Ltd | Radio receiver tuning |
| US4371978A (en) * | 1979-12-14 | 1983-02-01 | Jet Electronics And Technology Incorporated | Automatic tuning system |
| FR2481549A1 (en) * | 1980-04-25 | 1981-10-30 | Thomson Brandt | COMBINED SYNTHESIS AND DEMODULATION DEVICE FOR FREQUENCY-MODULATED WAVE RECEIVERS AND RECEIVER HAVING THE SAME |
| DE3419340A1 (en) * | 1984-05-24 | 1985-11-28 | Licentia Patent-Verwaltungs-Gmbh, 6000 Frankfurt | RADIO DEVICE FOR A VARIETY OF CHANNELS |
| DE3642365A1 (en) * | 1986-12-11 | 1988-06-16 | Grundig Emv | DEVICE FOR PROGRAMMING RECEIVER DEVICES |
-
1987
- 1987-10-09 JP JP25573687A patent/JPH0198100A/en active Pending
-
1988
- 1988-10-07 CA CA000579625A patent/CA1322037C/en not_active Expired - Fee Related
- 1988-10-07 GB GB8823662A patent/GB2211041B/en not_active Expired - Fee Related
- 1988-10-10 FR FR8813275A patent/FR2621703B1/en not_active Expired - Fee Related
Also Published As
| Publication number | Publication date |
|---|---|
| GB2211041A (en) | 1989-06-21 |
| GB2211041B (en) | 1992-01-29 |
| FR2621703A1 (en) | 1989-04-14 |
| JPH0198100A (en) | 1989-04-17 |
| FR2621703B1 (en) | 1991-10-04 |
| GB8823662D0 (en) | 1988-11-16 |
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| Date | Code | Title | Description |
|---|---|---|---|
| MKLA | Lapsed |