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OpenIF

Find open intermediate frequencies (IFs) in multiband transmitter or receiver architecture

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Description

Use the OpenIF object to analyze the spurs and spur-free zones in a multiband transmitter or receiver. This information helps you determine intermediate frequencies (IFs) that do not produce interference in operating bands.

Creation

Syntax

hif = OpenIF
hif = OpenIF(Name,Value)
hif = OpenIF(bandwidth)
hif = OpenIF(bandwidth,Name,Value)

Description

hif = OpenIF creates an intermediate-frequency (IF) planning object with properties set to their default values.

hif = OpenIF(Name,Value) creates an intermediate-frequency (IF) planning object with properties with additional options specified by one or more Name,Value pair arguments.

hif = OpenIF(bandwidth) creates an intermediate-frequency (IF) planning object with a specified IF bandwidth.

example

hif = OpenIF(bandwidth,Name,Value) creates an IF-planning object with a specified IF bandwidth and additional options specified by one or more Name,Value pair arguments.

Input Arguments

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Bandwidth of IF signal, specified as a real positive scalar. The value you provide sets the IFBW property of your object.

Properties

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Location of IF, specified as a 'MixerOutput' or 'MixerInput'.

  • Setting IFLocation to 'MixerInput' specifies an up-converting (transmitting) configuration, where one IF is mixed up to multiple RFs. The following figure shows this convention.

    Up-converting (transmitting) configuration

  • Setting IFLocation to 'MixerOutput' specifies a down-converting (receiving) configuration, where multiple RFs are mixed down to one IF. The following figure shows this convention.

    Down-converting (receiving) configuration

The setting of IFLocation determines the available values for the injection argument of the addMixer function.

Example: 'IFLocation','MixerInput'

Example: amplifier.IFLocation = 'MixerInput'

Maximum difference in magnitude between a signal at 0 dBc and an intermodulation product that the OpenIF object considers a spur, specified as a scalar in dBc.

Example: 'SpurFloor',80

Example: amplifier.SpurFloor = 80

System wide IF bandwidth, specified as a scalar in hertz. You can also set this property using the optional bandwidth input argument.

Example: 'IFBW',80

Example: amplifier.IFBW = 80

Object Functions

showGraphical summary of all relevant spurs and spur-free zones
reportSummarize IF planning results in command window

Examples

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Open Live Script

Set up an OpenIF object as a multiband receiver, add three mixers to it, and obtain information about its spur-free zones.

Define an OpenIF object. The first input is the bandwidth of the IF signal (50 MHz). The 'IFLocation','MixerOutput' name-value pair specifies a down-converting configuration. 

hif = OpenIF(50e6,'IFLocation','MixerOutput');

The following figure shows the down-converting configuration.

ifat_output_two.png

Define the first mixer with an intermodulation table and add it to the OpenIF object. Mixer 1 has a RF center frequency at 2.4 GHz, has a RF bandwidth of 100 MHz, and uses low-side injection.

IMT1 = [99 00 21 17 26; ...
        11 00 29 29 63; ...
        60 48 70 65 41; ...
        90 89 74 68 87; ...
        99 99 95 99 99];
addMixer(hif,IMT1,2.4e9,100e6,'low');

Mixer 2 has an RF center frequency at 3.7 GHz, has a bandwidth of 150 MHz, and uses low-side injection. 

IMT2 = [99 00 09 12 15; ...
        20 00 26 31 48; ...
        55 70 51 70 53; ...
        85 90 60 70 94; ...
        96 95 94 93 92];
addMixer(hif,IMT2,3.7e9,150e6,'low');

Mixer 3 has an RF center frequency at 5 GHz, has a bandwidth of 200 MHz, and uses low-side injection. 

IMT3 = [99 00 15 23 36; ...
        10 00 34 27 59; ...
        67 61 56 59 68; ...
        97 82 81 60 77; ...
        99 99 99 99 96];
addMixer(hif,IMT3,5e9,200e6,'low');

The multiband receiver is fully defined and ready for spur-free-zone analysis. Use the report method to analyze and display spur and spur-free zone information at the command line. The method also returns information about the mixers in the receiver. 

hif.report
     Intermediate Frequency (IF) Planner
     IF Location: MixerOutput
     
     -- MIXER 1 --
     RF Center Frequency: 2.4 GHz
     RF Bandwidth: 100 MHz
     IF Bandwidth: 50 MHz
     MixerType: low
     Intermodulation Table:   99   0  21  17  26
                              11   0  29  29  63
                              60  48  70  65  41
                              90  89  74  68  87
                              99  99  95  99  99
                            
     -- MIXER 2 --
     RF Center Frequency: 3.7 GHz
     RF Bandwidth: 150 MHz
     IF Bandwidth: 50 MHz
     MixerType: low
     Intermodulation Table:   99   0   9  12  15
                              20   0  26  31  48
                              55  70  51  70  53
                              85  90  60  70  94
                              96  95  94  93  92
                            
     -- MIXER 3 --
     RF Center Frequency: 5 GHz
     RF Bandwidth: 200 MHz
     IF Bandwidth: 50 MHz
     MixerType: low
     Intermodulation Table:   99   0  15  23  36
                              10   0  34  27  59
                              67  61  56  59  68
                              97  82  81  60  77
                              99  99  99  99  96
                            
     Spur-Free Zones:
        5.00 -    6.25 MHz
        6.25 -    8.33 MHz
        8.33 -  465.00 MHz
      495.00 -  581.25 MHz
      618.75 -  720.00 MHz
      760.00 -  775.00 MHz
      825.00 -  900.00 MHz
        1.03 -    1.16 GHz
        1.28 -    1.41 GHz
        1.52 -    1.56 GHz
        1.71 -    1.76 GHz
        2.04 -    2.17 GHz
        2.27 -    2.33 GHz
        2.56 -    2.71 GHz
        3.07 -    3.12 GHz
        3.44 -    3.51 GHz
        3.83 -    3.91 GHz
        4.09 -    4.35 GHz
        5.29 -    5.43 GHz
        5.73 -    5.79 GHz
        6.81 -    6.86 GHz
        7.66 -    7.84 GHz
        8.82 -    9.05 GHz
       10.23 -   10.85 GHz
       11.35 -   11.43 GHz
       13.61 -   14.08 GHz
       15.33 -   18.10 GHz
       18.90 -   19.58 GHz
       20.43 -   21.73 GHz
       22.68 -   24.48 GHz

Use the show method to analyze the receiver and produce an interactive spur graph. Generating a spur graph is a convenient way to summarize the results of the analysis graphically. 

figure;
hif.show

Version History

Introduced before R2006a

See Also

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