GB2211041A - Airborne receiver in microwave landing system - Google Patents
Airborne receiver in microwave landing system Download PDFInfo
- Publication number
- GB2211041A GB2211041A GB8823662A GB8823662A GB2211041A GB 2211041 A GB2211041 A GB 2211041A GB 8823662 A GB8823662 A GB 8823662A GB 8823662 A GB8823662 A GB 8823662A GB 2211041 A GB2211041 A GB 2211041A
- Authority
- GB
- United Kingdom
- Prior art keywords
- mls
- signal
- frequency
- channel
- receiver
- 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.)
- Granted
Links
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
Landscapes
- Engineering & Computer Science (AREA)
- Computer Hardware Design (AREA)
- Microelectronics & Electronic Packaging (AREA)
- Computer Networks & Wireless Communication (AREA)
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Radar, Positioning & Navigation (AREA)
- Remote Sensing (AREA)
- Circuits Of Receivers In General (AREA)
- Traffic Control Systems (AREA)
- Channel Selection Circuits, Automatic Tuning Circuits (AREA)
Abstract
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 16 for enabling to input airport name abbreviations which are familiar to and readily remembered by the pilot. A storage unit 17 memorizes a table (Fig 2) of the abbreviations and selection codes corresponding to the airports. The storage unit 17 reads a particular selection code corresponding to a particular abbreviation of a destination airport input by the keyboard. A control circuit 18 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. The local oscillator 13 may be a frequency synthesizer (Fig 3) having a variable division ratio divider (18) connected in a phase locked loop (22-23). <IMAGE>
Description
AIRBORNE RECEIVER IN MICROWAVE LANDING SYSTEM
WTTH CHANNEL SELECTION MEANS BY MANUAL PUT OF FAMILIAR ABBREVIATIONS OF AIRPORTS
The present invention relates to a microwave landing system (MLS) and, in particular, to an airborne receiver for use in the MLS.
As a standard of a landing system for guiding an aircraft onto runway with safety, the instrument landing system (ILS) has been used for a long time. Recently, the MLS has been proposed as one which will take the place ot 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).
The MLS comprises MLS ground stations installed at airports and airborne receivers carried on aircraft.
The MLS ground stations transmit MLS signals of frequency bands or channels individually assigned thereto. The frequency band of 5031 - 5090.7 Hz and 200 channels of channel Nos. 500 to 699 are provided to be assigned to individual MLS ground stations of airports, When an aircraft approaches a destination airport, the aircraft receives a particular MLS channel signal from the MLS ground station of the destination airport by its airborne receiver which is called "MLS receiver" so as to know the azimuth, the elevation and distance to the destination airport.
The MLS receiver comprises a tuning circuit or a 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. Zn a conventional MLS receiver, the channel selection circuit is a superheterodyne type which comprises a local oscillator of a frequency synthesizer type and a mixer.
The oscillating frequency of the local oscillator is adjusted by the channel selection dial. When the aircraft approaches the destination airport, an operator or a pilot of the aircraft must manually operate the channel selection dial of the MLS receiver to select the particular MLS channel of the MLS ground station of the destination airport. As a result, the channel selection circuit is adjusted to tune the MLS receiver to the particular MLS channel to thereby receive the particular MtS 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 ES channel signal to frequency convert the particular MLS signal to an intermediate frequency (IF) signal of a fixed IF frequency. Thus, the MbS receiver is tuned to the particular MLS channel and the particular MLS channel signal ii tzinçd as the ZF 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 operate the channel selection dial. It is complicated for the pilot to refer to the list.
It is an object of the present invention to provide an airborne MLS receiver wherein the MLS channel selecting operation of the destination airport can readily be performed without use of the list.
It is another object of the present invention to provide an airborne MLS receiver 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.
The present invention is applicable to an airborne MLS (Microwave Landing System) receiver for use in an MLS comprising a channel selection circuit for selecting a particular one of MLS channels of MLS signals from MI;S ground stations installed at airports having abbreviations familiar to pilots.According to the present invention, the MLS receiver comprises input means for manually wutting the SFreviation of a destination airport as a particular abbreviation; and storage means for memorizing a table of channel selection codes of MLS channel numbers assigned to the
MtS ground stations of airports and the abbreviations of the airports, the storage means coupled to the input means and responsive to the particular abbreviation for reading a particular one of-the channel selection codes of MtS channel numbers corresponding to the particular abbreviation from the table.The channel selection circuit comprises a control circuit coupled to the storage means and responsive to the particular channel selection code of the MLS channel number for controlling the. channel selection circuit to select the particular MtS channel to thereby receive the particular MLS channel signal.
According to an aspect of the present invention, the channel selection circuit 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 XF frequency to thereby receive the specific
MLS channel signal.The local oscillator is provided with the control circuit which 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 particular MLS channel signal and the XF signal, whereby the mixer circuit converts the particular MLS channel signal as the specific MLS channel signal to the IF signal.
According to another aspect, the local oscillator is a frequency synthesizer type having a variable frequency divider as the control circuit.
According to still another aspect, the input means is a conventional alphabetic keyboard.
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 is a block diagram view of an example of a local oscillator.
Referring to Fig. 1, the MLS receiver shown therein comprises a radio frequency (RF) bandpass filter (BYh") 11 for filterifl the MLS frequency band signal from an incoming signal through an antenna 10.
The MLS frequency band signal is applied to a channel selection circuit 12. In the present embodiment, the channel selection circuit 12 is the superheterodyne type and comprises a local oscillator 13 and a mixer 14.
Sn the prior art, a channel selection dial is provided to adjust an oscillating frequency of the local oscillator 13 to select a desired one of the MLS channels, and the desired MLS channel signal is obtained as the IF signal from the channel selection circuit 12, as described in the preamble.
The IF signal is artplifled at an IF arrplifier (AMP) 15 and is thereafter processed at a processing circuit (not shown) which is known in the prior axt.
The MLS receiver according to the present embodiment comprises an input unit 16 and a storage unit 17 in place of the channel selection dial.
The input unit 16 is a keyboard, for example, a conventional alphabetic keyboard for inputting an abbreviation of an airport name or a keyboard comprising a plurality of keys corresponding to 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)11 is a channel selection code for selecting the MLS channel (No0 602) of the MLS ground station of the Wexford County Airport.
The storage unit 17 in response 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 dn 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 MtjS channel signal to convext the particular MLS signal to an IF signal, in the similar manner as the conventional channel selection circuit of a superheterodyne type as described in the preamble.
Now, it is assumed that the.MLS receiver has the fixed IF frequency of 160.8 MHz. When the abbreviation "CAD" of the airport is set at the input unit 16, the storage unit 17 applies the corresponding channel selection code Rum(602)" to the control circuit 18. The channel number of the airport is 602 which is corresponding to a frequency of 5061.6 MHz. In order to receive the MLS signal of 5061.6 MHz, the local oscillating frequency in the receiver is set at 4900,8 MHz which is equal to (5061.6 MHz - 160.8 MHz).
Therefore, the control circuit 18 controls the local oscillator 13 to produce a particular local signal which'has a frequency of 4900.8 MHz, The particular local signal of 4900.8 z is applied to the mixer 141 from which the MLS channel signal from the "CAD" airport is obtained as the IF signal, The IF signal is applied to the Zr amplifier 15.
Referring to Fig. 3, the local oscillator 13 may be a frequency synthesizer which comprises a fixed frequency oscillator 19 for oscillating an oscillating signal of a fixed frequency of, for example, 10 MHz, a counter or fixed frequency divider 20 for frequency dividing the oscillating signs t a fixed dividing ratio of 1/M (M = 200) to produce a divided signal, a phase locked loop, and a multiplier 21 with a multiplying ratio of, for example, 6.
The PLL comprises a voltage controlled oscillator (VCO) 22 for oscillating a VCO signal, a variable frequency divider 18' as the control circuit for frequency dividing the VCO signal at a dividing ratio set thereat to produce a variable frequency divided signal, a phase detector 23 for comparing the divided signal and the variable frequency divided signal to detect a phase difference therebetween as an error signal, and a loop filter 24 for removing a high frequency signal catponent to derive the error signal which is applied to the VCO 22 so as to stabilize a frequency of the VCO signal,
The variable frequency divider 18' is a programmable counter to which a variable dividing ratio is set as the channel selection codes by the storage unit 17. Zn response to input of an airport name abbreviation at the input unit 16, a corresponding dividing ratio is delivered from the storage unit 17 to set it in the frequency divider 18'. The dividing ratio is applied to the frequency divider 18' from the storage unit 17 to control b frequency of the VCO signal.Then, the VCO signal is frequency multiplied 6 b at tne multiplier ti to psuduce wlle lucal signal.
In this connection, the dividing ratios as the channel selection codes are previously determined with reference to the fixed frequency of the fixed frequency oscillator 19, the MLS channels, the IF frequency, dividing ratio, and the multiplying ratio, as shown in the followi-ng table.
TABLE
Channel Number 500 602 699 Frequency (MHz) 5031 5061.6 5090.7 Fixed Frequency (MHz) 10 Fixed Dividing Ratio (M) 200 Variable Dividing 16234 16336 16433 Ratio (N) VCo Frequency = 811.7 816.8 821.65 Multiplying Ratio 6 Controlled Frequency 4870.2 4900.8 4929.9 (MHz) IF Frequency (MHz) 160.8 Airport name abbreviations are used in the above-mentioned embodiment, but alphabetic station codes of the MLS ground stations of the airports, which are familiar to pilots, can be used in place of the airport name abbreviations. For instance, the MLS ground station at the "CADS" airport has an alphabetic station code "MAJE". Therefore, "MAJE" is described adjacent "CAD" but with a parenthesis in the table of
Fig. 2,
Claims (8)
1. An airborne MLS (Microwave Landing System) receiver for use in an MLS 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 improvement comprises:
input means for manually inputting the abbreviation of a destlnation airport as a particular abbreviation; and
storage means for memorizing a table of channel selection codes of MLS channel numbers assigned to the
MLS ground stations of airports and the abbreviations of the airports, said storage means coupled to said input means and responsive to said particular abbreviation for reading a particular one oe said channel selection codes of MLS channel numbers corresponding to said particular abbreviation from said table;
said channel selection-circuit comprising a control circuit coupled to said storage means and respon-sive to said particular channel selection code of the MLS channel number for controlling said channel selection circuit to select the particular MLS channel to thereby receive the particular xLS channel signal.
2, An airborne ML9 receiver as claimed in Claim 1, said channel selection circuit comprising a local oscillator of a variable frequency type for oscillating (Claim 2 continued) 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 to thereby 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 particular MLS channel signal and said IF signal, whereby said mixer circuit converts said particular mS channel signal as said specific MtS 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 as said control circuit,
4. An airborne MLS receiver as claimed in
Claim 3, wherein said frequency synthesizer comprises a fixed frequency oscillator for aselllating 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 for oscillating a VCO signal, a variable frequency divider (Claim 4 continued) as said control circuit for frequency dividing said VCO signal at a variable dividing ratio set thereat 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 signal 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 abbreviations are abbreviation names of the airports.
6. An airborne MLS receiver as claimed in
Claim l, wherein said abbreviations are alphabetic station codes assigned to said MLS ground stations installed at the airports.
7. An airborne MLS receiver as claimed in
Claim 1 wherein said input means is an alphabetic keyboard
8. An airborne MLS receiver constructed, arranged and adapted to operate substantially as hereinbefore described with reference to, and as illustrated in, the accompanying drawings.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP25573687A JPH0198100A (en) | 1987-10-09 | 1987-10-09 | Mls receiver |
Publications (3)
| Publication Number | Publication Date |
|---|---|
| GB8823662D0 GB8823662D0 (en) | 1988-11-16 |
| GB2211041A true GB2211041A (en) | 1989-06-21 |
| GB2211041B GB2211041B (en) | 1992-01-29 |
Family
ID=17282917
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB8823662A Expired - Fee Related GB2211041B (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) |
Cited By (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 |
Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1265331A (en) * | 1968-03-07 | 1972-03-01 | ||
| GB1538294A (en) * | 1975-10-16 | 1979-01-17 | Indesit | Circuit arrangement for the selection of a frequency of signals receivable in a receiving set |
| GB2064905A (en) * | 1979-11-30 | 1981-06-17 | Smiths Industries Ltd | Radio receiver tuning |
Family Cites Families (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4122395A (en) * | 1976-05-10 | 1978-10-24 | Draco Laboratories, Inc. | Radio control circuit with microprocessor |
| 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
Patent Citations (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1265331A (en) * | 1968-03-07 | 1972-03-01 | ||
| GB1538294A (en) * | 1975-10-16 | 1979-01-17 | Indesit | Circuit arrangement for the selection of a frequency of signals receivable in a receiving set |
| GB2064905A (en) * | 1979-11-30 | 1981-06-17 | Smiths Industries Ltd | Radio receiver tuning |
Cited By (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 |
Also Published As
| Publication number | Publication date |
|---|---|
| CA1322037C (en) | 1993-09-07 |
| GB2211041B (en) | 1992-01-29 |
| GB8823662D0 (en) | 1988-11-16 |
| JPH0198100A (en) | 1989-04-17 |
| FR2621703A1 (en) | 1989-04-14 |
| FR2621703B1 (en) | 1991-10-04 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PCNP | Patent ceased through non-payment of renewal fee |
Effective date: 20011007 |