OpenIF
Find open intermediate frequencies (IFs) in multiband transmitter or receiver architecture
Description
Use the OpenIF class 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
Description
hif = OpenIF
hif = OpenIF(Name,Value)Name,Value
pair arguments.
hif = OpenIF(bandwidth)
Input Arguments
Properties
IF Location — Location of IF
'MixerOutput' (default) | 'MixerInput'
Location of IF, specified as a 'MixerOutput' or
'MixerInput'.
Setting
IFLocationto'MixerInput'specifies an up-converting (transmitting) configuration, where one IF is mixed up to multiple RFs. The following figure shows this convention.
Setting
IFLocationto'MixerOutput'specifies a down-converting (receiving) configuration, where multiple RFs are mixed down to one IF. The following figure shows this convention.
The setting of IFLocation determines the available
values for the injection argument of the addMixer function.
Example: 'IFLocation','MixerInput'
Example: amplifier.IFLocation =
'MixerInput'
SpurFloor — Maximum spur value
99 (default) | scalar
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
IFBW — System wide IF bandwidth
99 (default) | scalar
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
Examples
Spur-free zones of a multiband receiver
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');
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:
350.00 - 430.00 MHz
530.00 - 556.25 MHz
643.75 - 655.00 MHz
1.38 - 1.41 GHz
2.10 - 2.17 GHz
2.28 - 2.29 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
