WO2012011141A1 - Process for automatically calibrating wideband microwave modules" - Google Patents
Process for automatically calibrating wideband microwave modules" Download PDFInfo
- Publication number
- WO2012011141A1 WO2012011141A1 PCT/IT2011/000257 IT2011000257W WO2012011141A1 WO 2012011141 A1 WO2012011141 A1 WO 2012011141A1 IT 2011000257 W IT2011000257 W IT 2011000257W WO 2012011141 A1 WO2012011141 A1 WO 2012011141A1
- Authority
- WO
- WIPO (PCT)
- Prior art keywords
- band
- circuit
- calibration
- alignment
- spec
- Prior art date
Links
Classifications
-
- 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
- G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
- G01S7/02—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S13/00
- G01S7/40—Means for monitoring or calibrating
- G01S7/4004—Means for monitoring or calibrating of parts of a radar system
- G01S7/4017—Means for monitoring or calibrating of parts of a radar system of HF systems
Definitions
- the present invention relates to a process for automatically calibrating microwave modules able to operate in a wide range of radio signal frequencies and strengths.
- microwave modules which process these signals must ensure that the amplitude of the signal remains constant within the entire operating band, while the basic components, amplifiers, filters and attenuators, which are used in said microwave modules, tend to have a non-uniform behaviour within the band and normally tend to distort the signal, attenuating it with an increase in the frequency.
- modules and in particular those modules associated with wideband receivers, must operate in a wide frequency band and with signals which, since they may have widely differing strengths, require filtering structures with optimum selectivity, dynamic-range and equalization characteristics in order to obtain intermediate band signals with a constant amplitude and phase upon variation in the frequency and strength characteristics of the signal received, while ensuring at the same time the necessary sensitivity and linearity required for correct operation thereof.
- the need for alignment, according to the design specification, of the signal output by the microwave module requires that compensation of the module transfer function be introduced so that the signal supplied at the output is not distorted and is contained within a pre-defined dynamic range upon variation in the frequency and the power of the signal received.
- the alignment operation i.e. the operation which ensures that the output signal complies with the requisites of the design specification upon variation in the input signal
- special circuits consisting of basic components which can be calibrated (filters, attenuators, amplifiers and equalizers) able to align the signal received to the specification requirements; these circuits must be able to be calibrated since, during design both of the individual components which form them and of the circuit as a whole, tolerances are defined which are not sufficiently small to ensure compliance with the necessary operating specification.
- the calibration and test activity becomes even more critical when the apparatus is required to function, according to specification, within a wide temperature range, as occurs for example in the aforementioned applications and in particular when this is required for receiver systems which operate in a temperature range of -40 to 70°C, since there is a further variability in the parameters which is dependent not only on the temperature, but also on the basic components and therefore the transfer function of the circuit itself.
- the various components of the alignment circuit may be calibrated manually; however, especially with regard to equalizers, calibration is particularly complex since each component must be calibrated individually and/or replaced manually, until the combination which complies with the system requirements is found.
- wideband frequency generators of the synthesized type whether they be phase/frequency locked-loop (PLL/FLL) synthesizers or direct digital synthesizers (DDS), since they have a variable-frequency voltage controlled oscillator (VCO) and are used in the field of communications with a very wide radiofrequency band, require correction of the amplitude of the output characteristic so as to compensate for the variations due to the different set frequency and changes in temperature.
- PLL/FLL phase/frequency locked-loop
- DDS direct digital synthesizers
- VCO variable-frequency voltage controlled oscillator
- the technical problem which is posed, therefore, is provide a process for allowing rapid automatic calibration of wideband microwave modules, which is to a large extent independent of the abilities of the individual operator responsible for performing the operation.
- the process should be simple to implement and allow a reduction in the complexity and corresponding production costs of the said devices to be calibrated.
- Figure 1 shows the circuit diagram of an example of a microwave module to be calibrated
- Figure 2 shows the circuit diagram of an example of embodiment of a variable amplifier for an alignment circuit according to the present invention
- Figure 3 shows the circuit diagram of an example of embodiment of a variable attenuator for an alignment circuit according to the present invention
- Figure 4 shows the circuit diagram of an example of embodiment of a variable equalizer for an alignment circuit according to the present invention
- Figure 5 shows the flow diagram illustrating the process for calibrating a microwave module according to the present invention
- Figures 6, 7 and 8 show the block diagram of a comb generator during calibration and the respective graphs for its output before and after calibration
- FIGS 9, 10 and 11 show the block diagram of a synthesized generator during calibration and the respective graphs for its output before and after calibration.
- a microwave module for receiving wideband frequency signals (ranging from radio frequencies to millimetric waves), which may be calibrated and tested by means of the process according to the present invention, comprises:
- an input block 1000 connected to the wideband antenna, from which it receives:
- a switch 1010 which, receiving any one of the input signals, sends them to a filter 1015 in order to limit their operative frequency band and therefore reduce their harmonics or the spurious emissions produced by unwanted signals;
- a dynamics block 2000 which receives at its input the signal output by the filter 1015 and has the function of adjusting the dynamic range thereof.
- This module contains a high-sensitivity circuit 2010 which comprises a signal limiter 2011 inserted so as to protect a following low noise figure amplifier 2012 in the presence of signals with high strength levels, these components being followed by an attenuator 2013 and by an amplifier 2014 which have the function of ensuring the gain, the dynamic range and the design sensitivity along the high-sensitivity path.
- a high-sensitivity circuit 2010 which comprises a signal limiter 2011 inserted so as to protect a following low noise figure amplifier 2012 in the presence of signals with high strength levels, these components being followed by an attenuator 2013 and by an amplifier 2014 which have the function of ensuring the gain, the dynamic range and the design sensitivity along the high-sensitivity path.
- the signal 2010a output by the high-sensitivity circuit 2010 is intercepted by a recognition circuit 2020 by means of which it is possible to detect the strength of each signal and drive a corresponding switch 2030 which diverts each signal to a corresponding attenuator 2031, 2032, 2033 of different value.
- At least one basic alignment circuit 3100 for at least one signal within a given frequency band the number of basic alignment circuits depends on the number of output bands from the preselector module; the example according to Figure 1 shows three basic alignment circuits.
- Each basic alignment circuit 3100 comprises at least one filter 3110, followed by at least one variable amplifier 3120, by a variable attenuator 3130 and by a variable equalizer 3140 which are arranged in series and the voltage of which can be controlled, so as to be able to perform calibration of each channel.
- the basic alignment circuits also comprise a further output filter 3300 and are connected to a switch 3400 which selects the circuit and therefore the corresponding signal 3400a to be sent to a following frequency conversion block 4000.
- the block 4000 which performs conversion to the intermediate frequency of the incoming signal 3400a at the microwave/RF band frequency.
- Said block 4000 comprises at its input a variable-gain amplifier 4201 and a variable attenuator 4202 followed by a frequency converter 4100 which receives at its input also a signal 4101 from a local oscillator which generates the tuning frequencies for converting the high- frequency channels into intermediate-frequency channels for subsequent processing.
- the block 4000 also comprises a filter 4250, an amplifier 4300 and variable attenuator 4400 arranged in series so that it is possible to compensate for the maximum output power and the mean value of the gain in the entire operating band, before the signal is sent to the output 4002 for subsequent processing.
- Figures 2, 3 and 4 show examples of functional/electrical diagrams of said basic components, amplifier, attenuator and equalizer which can be calibrated and form the basic alignment circuits.
- FIG. 2 shows the functional diagram of an amplifier 3120, the gain of which can be varied by modifying the gate voltage VI applied to the input 3121 of the device.
- the amplifier is designed by means of the known "travelling" solution via which it is possible to obtain wideband amplification.
- the input signal for example supplied by the switch 3020, is introduced into the connector 3124 and the amplified output is extracted by the output connector 3125.
- the six GaAS FETs 3126 in a dual gate configuration, which amplify the signal, are polarized by means of the drain voltage V2 applied to the input 3122 and the gate voltages VI and V3 applied to the respective input 3121 and 3123.
- the induction lines 3128 of gates connected to the capacitances Cgs 3128a of the FETs and the drain induction lines 3129 connected to the capacitances Cds 3129a of the FETs form two low-pass filters.
- Figure 3 shows the functional diagram of a variable attenuator 3130, the function of which is to vary the average frequency attenuation.
- the operating principle is that of a conventional pi attenuator.
- V4 at the input 3134, for the PIN diodes CR1 and CR2, and the voltage V5 at the input 3135, for the diode PIN CR3, it is possible to vary the three junction resistances thereof and therefore the attenuation of the device.
- the direct voltage values on the three diodes must be suitably set taking account also of adaptation of the device on the line with a characteristic impedance of 50 ohm.
- Figure 4 shows the functional diagram of an equalizer 3140 which has a slope variable discretely - forming the subject of the co-pending patent application IT-RM2009A000022 referred to here in its entirety - and which has between the input gate 3141 and the output gate 3142 a transfer/attenuation function inversely proportional to the frequency and adjustable by means of the voltages V6 applied to the input 3146 and the voltage V7 applied to the input 3147, which determine the different conduction/inhibiting conditions of the diodes D3, D4, and Dl, D2 able to compensate for the effect of loss of insertion of a radiofrequency chain which is generally directly proportional to the frequency.
- this device introduces a characteristic which is the inverse of that of the RF chain, by suitably adjusting the voltages V6 and V7, it is possible to obtain a function for transfer of the flat unit into frequency.
- variable equalizer By suitably programming the variable equalizer, it is possible to compensate automatically for the variation in the slope produced by the tolerances of the components used in the RF chain of the modules in question.
- the microwave module is equipped with a controller 5000 of the PLC type (programmable logic device) provided with its own static memory by means of which it is possible to control the said regulating voltages (V1,V2,V3,V4,V5,V6,V7).
- a controller 5000 of the PLC type programmable logic device
- FIG. 5 illustrates in the form of a flow diagram the process used for automatic alignment of the said microwave module which comprises the following steps:
- Gtot-m-spec Total average gain, according to specification, of the module
- Gm-max-spec Maximum gain of the alignment circuit, according to specification, for each band;
- Gm-min-spec Minimum gain of the alignment circuit, according to specification, for each band; • definition of the temperatures T1,T2, ... Ti at which the automatic calibration cycles must be performed.
- the nominal start-of-procedure voltages (Vli, V2i, V3i, V4i, V5i, V6i, V7i) are determined on the basis of the design calculations and by means of tests on the calibration and alignment bench carried out on the prototypes;
- the amplification 3120 is increased and the attenuation 3130 is increased in the basic alignment circuit for the band Bi corresponding to Gm-min by adjusting the voltage VI of the associated amplifiers and the voltages V4,V5 of the associated attenuators;
- the process according to the invention envisages further calibration steps comprising:
- the values of the alignment voltages of the basic components of the circuit are defined only for certain working temperatures (three: - 40, 25, 70°C in the example), the values of the voltages for alignment with the intermediate temperatures are calculated by means of interpolation of the values determined during calibration.
- the programmable logic device installed in the module reads every second the temperature information by means of a digital temperature sensor and, based on the values of the alignment voltages defined during calibration for the three said calibration temperatures, calculates by means of interpolation the values of the optimum alignment voltages to be applied in the specific situation.
- the automatic calibration process may be applied to the alignment circuits of wideband microwave frequency generators.
- Figure 6 shows a wideband frequency generator with frequency components distributed within the spectrum of the working frequencies. This generator, owing to the distribution of its components over a certain number of frequencies, is commonly referred to as a "comb generator”.
- a possible defect of this type of generator is the relative lack of uniformity in the amplitude of the output components la of the circuit 1 ( Figure 7) and the relative instability of the amplitude depending on the temperature.
- the automatic calibration system will maintain a constant value for preselection of the variable amplifier and for preselection of the attenuator and will adjust exclusively equalization; it will therefore supply the control parameters to the alignment circuits and these will be stored in the module memory.
- Figure 9 shows the block diagram of a synthesized variable frequency generator 2, of the phase/frequency locked-loop (PLL/FLL) type or direct digital synthesizer (DDS) type, followed by an associated alignment circuit 3000.
- PLL/FLL phase/frequency locked-loop
- DDS direct digital synthesizer
- the progression of the amplitude of the signal 2a output by the generator 2 may vary with variation of the frequency within the operating band as shown in Figure 10.
- the calibration procedure will maintain a constant value for preselection of the variable amplifier and the attenuator and will adjust exclusively equalization.
- the automatic calibration system will then supply the control parameters thus determined to the alignment circuits and these will be stored in the module memory.
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- Engineering & Computer Science (AREA)
- Radar, Positioning & Navigation (AREA)
- Remote Sensing (AREA)
- Computer Networks & Wireless Communication (AREA)
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Amplifiers (AREA)
- Measurement Of Resistance Or Impedance (AREA)
- Stabilization Of Oscillater, Synchronisation, Frequency Synthesizers (AREA)
- Control Of Motors That Do Not Use Commutators (AREA)
- Microwave Amplifiers (AREA)
- Testing Electric Properties And Detecting Electric Faults (AREA)
- Networks Using Active Elements (AREA)
Abstract
Description
Claims
Priority Applications (4)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
BR112013001554A BR112013001554A2 (en) | 2010-07-21 | 2011-07-20 | process for automatically calibrating broadband microwave modules |
EP11754535.0A EP2596378A1 (en) | 2010-07-21 | 2011-07-20 | Process for automatically calibrating wideband microwave modules" |
SG2012049516A SG182360A1 (en) | 2010-07-21 | 2011-07-20 | Process for automatically calibrating wideband microwave modules |
IL223064A IL223064A0 (en) | 2010-07-21 | 2012-11-15 | Process for automatically calibrating wideband microwave modules |
Applications Claiming Priority (2)
Application Number | Priority Date | Filing Date | Title |
---|---|---|---|
ITRM2010A000406A IT1401722B1 (en) | 2010-07-21 | 2010-07-21 | PROCEDURE FOR AUTOMATIC CALIBRATION OF BROADBAND MICROWAVE MODULES |
ITRM2010A000406 | 2010-07-21 |
Publications (1)
Publication Number | Publication Date |
---|---|
WO2012011141A1 true WO2012011141A1 (en) | 2012-01-26 |
Family
ID=43589709
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
---|---|---|---|
PCT/IT2011/000257 WO2012011141A1 (en) | 2010-07-21 | 2011-07-20 | Process for automatically calibrating wideband microwave modules" |
Country Status (6)
Country | Link |
---|---|
EP (1) | EP2596378A1 (en) |
BR (1) | BR112013001554A2 (en) |
IL (1) | IL223064A0 (en) |
IT (1) | IT1401722B1 (en) |
SG (1) | SG182360A1 (en) |
WO (1) | WO2012011141A1 (en) |
Cited By (1)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2013126952A1 (en) | 2012-02-29 | 2013-09-06 | Micreo Limited | An electronic gain shaper and a method for storing parameters |
Families Citing this family (2)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
RU2621329C1 (en) * | 2016-06-02 | 2017-06-02 | Российская Федерация, от имени которой выступает Государственная корпорация по атомной энергии "Росатом" | Method of radio signal imitation |
RU189247U1 (en) * | 2019-02-21 | 2019-05-17 | Федеральное государственное автономное образовательное учреждение высшего образования "Уральский федеральный университет имени первого Президента России Б.Н. Ельцина" | SIMULATOR OF REFLECTED RADAR SIGNALS |
Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5809420A (en) * | 1996-05-31 | 1998-09-15 | Fujitsu Limited | Transmission power control apparatus |
WO2000025445A1 (en) * | 1998-10-28 | 2000-05-04 | Tachyon, Inc. | Method and apparatus for calibration of a wireless transmitter |
WO2001011769A1 (en) * | 1999-08-04 | 2001-02-15 | Harris Corporation | Methods for calibration of radio devices at room temperature |
ITRM20090022A1 (en) | 2009-01-23 | 2010-07-24 | Sie Soc It Elettronica | CURVED EQUALIZER OF VARIABLE TRANSFER |
-
2010
- 2010-07-21 IT ITRM2010A000406A patent/IT1401722B1/en active
-
2011
- 2011-07-20 WO PCT/IT2011/000257 patent/WO2012011141A1/en active Application Filing
- 2011-07-20 SG SG2012049516A patent/SG182360A1/en unknown
- 2011-07-20 EP EP11754535.0A patent/EP2596378A1/en not_active Withdrawn
- 2011-07-20 BR BR112013001554A patent/BR112013001554A2/en not_active IP Right Cessation
-
2012
- 2012-11-15 IL IL223064A patent/IL223064A0/en unknown
Patent Citations (4)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US5809420A (en) * | 1996-05-31 | 1998-09-15 | Fujitsu Limited | Transmission power control apparatus |
WO2000025445A1 (en) * | 1998-10-28 | 2000-05-04 | Tachyon, Inc. | Method and apparatus for calibration of a wireless transmitter |
WO2001011769A1 (en) * | 1999-08-04 | 2001-02-15 | Harris Corporation | Methods for calibration of radio devices at room temperature |
ITRM20090022A1 (en) | 2009-01-23 | 2010-07-24 | Sie Soc It Elettronica | CURVED EQUALIZER OF VARIABLE TRANSFER |
Cited By (3)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
WO2013126952A1 (en) | 2012-02-29 | 2013-09-06 | Micreo Limited | An electronic gain shaper and a method for storing parameters |
EP2820487A4 (en) * | 2012-02-29 | 2016-04-06 | Micreo Ltd | An electronic gain shaper and a method for storing parameters |
US10735040B2 (en) | 2012-02-29 | 2020-08-04 | L3Harris Technologies | Electronic gain shaper and a method for storing parameters |
Also Published As
Publication number | Publication date |
---|---|
SG182360A1 (en) | 2012-08-30 |
IL223064A0 (en) | 2013-02-03 |
BR112013001554A2 (en) | 2016-05-24 |
IT1401722B1 (en) | 2013-08-02 |
ITRM20100406A1 (en) | 2012-01-22 |
EP2596378A1 (en) | 2013-05-29 |
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