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Custom IQ - ASK & PSK & QAM

The Custom IQ Type: APSK & PSK & QAM waveform setup allows you to configure a frame with multiple data segments and/or idle segments. For each data segment, the modulation type can be further configured using a graphical constellation settings editor.

Quick Setups

Use this Closed drop-down menu to select a modulation type from several supported formats. A single data segment using that modulation type appears in the segment list below. Click the cell in the Constellation column to open the Constellation Setting window, providing a graphical display and editing features (video). Quick setups enable you to configure complex signals for signal generation, equivalent to 89600B VSA setups in signal analysis.

Quick Setups IQ Settings

Standard		Modulation	Symbol Rate	Filter
APCO25	C4FM	4FSK (0.6 kHz, 1.8 kHz, -0.6 kHz, -1.8 kHz)	4.8 ksps	NYQ (0.2) + 1/Sinc
	CQPSK*	Pi/4 DQPSK	4.8 ksps	NYQ
	HCPM	4FSK (1 kHz, 3 kHz, -1 kHz, -3 kHz)	6 ksps	APCO25 HCPM
	HDQPSK	Pi/4 DQPSK	6 ksps	APCO25 HDQPSK
TETRA		Pi/4 DQPSK	18 ksps	RNYQ (0.35)
NXDN	4800 bps	4FSK (0.35 kHz, 1.05 kHz, -0.35 kHz, -1.05 kHz)	2.4 ksps	RNYQ (0.2) + Sinc
NXDN	9600 bps	4FSK (0.8 kHz, 2.4 kHz, -0.8 kHz, 2.4 kHz)	4.8 ksps	RNYQ (0.2) + Sinc
dPMR		4FSK (0.35 kHz, 1.05 kHz, -0.35 kHz, -1.05 kHz)	2.4 ksps	RNYQ (0.2)
DECT		2FSK (-288 kHz, 288 kHz)	1.152 Msps	Gaussian (0.5)
DMR		4FSK (0.648 kHz, 1.944 kHz, -0.648 kHz, -1.944 kHz)	4.8 ksps	RNYQ (0.2)
ARIB	T98/T61*	Pi/4 DQPSK	9.6 ksps	RNYQ (0.2)
ARIB	T102	4FSK (0.33 kHz, 0.99 kHz, -0.33 kHz, -0.99 kHz)	4.8 ksps	ARIB T102 RNYQ (0.2) + Gaussian (0.769)
Zigbee	BPSK	BPSK	600 ksps	NYQ (1)
Zigbee	OQPSK	OQPSK	1 Msps	Half Sine
WiSUN	2FSK 50/1	2FSK (-25 kHz, 25 kHz)	50 ksps	Gaussian (0.5)
WiSUN	2FSK 100/0.5	2FSK (-25 kHz, 25 kHz)	100 ksps	Gaussian (0.5)
ITU-T G.9959	R2	2FSK (-20 kHz, 20 kHz)	40 ksps	Rectangle
ITU-T G.9959	R3	2FSK (-29 kHz, 29 kHz)	100 ksps	Gaussian (0.6)

* For APCO25 CQPSK and ARIB T98/T61, the ALC is set to off to achieve better EVM. For all other cases, the ALC is on.

Payload, Idle Interval, Ramp Symbols, and Number of Symbols will be set to default values.

Save to 89600B Setup File

This feature saves the Custom IQ configuration as an 89600B VSA setup file, making it easier to configure complex constellations, such as 256APSK.

VSA software must be version 18.0 or later to support Custom IQ demodulation. If there is more than one data segment configured in the list, only the selected data segment (indicated by the graphical display at the bottom) will be saved to the VSA setup file. Idle segments cannot be saved to the setup file.

ASK & PSK & QAM

Differential and offset modulation types (e.g. pi/4 DQPSK or OQPSK) are found under DigitalDemod on the VSA.

The VSA does not support the APCO25 HDQPSK filter.

FSK

FSK configurations are found under DigitalDemod on the VSA.

The VSA does not support ARIB T102 and NXDN filters.

For added convenience, you can save the VSA setup as a quick setup in the VSA's Custom IQ Demod Property window. To do this, recall the Signal Studio VSA setup file, perform the measurement, and then click Save As Quick Setup. Now, whenever you click Quick Setups, you will find your previously saved setup listed among the other setups provided with the VSA software. Using this method, you no longer need to recall the Signal Studio VSA setup file each time you want to perform a measurement.

1. Custom IQ Selection

Custom IQ Type

Choices: ASK & PSK & QAM | FSK | SOQPSK | ARTM Multi-h CPM

Default: ASK & PSK & QAM

Select the type of Custom IQ.

2. Custom ASK PSK QAM Settings

Symbol Rate

Range: 1 kSa/s to 4 GSa/s

Default: 1 MSa/s

Sets the symbol rage of the waveform.

Filter

Default: Root Nyquist

Select the filter type to be applied to the waveform.

Alpha

Range: 0.01 to 1.0

Default: 0.5

Sets the alpha factor of the Root Nyquist or Nyquist filter.

Filter Coefficient

Opens a Closed Filter Editor window where you can import, export, and edit filter coefficients. A convenient plot of the filter's impulse response is displayed and updates as coefficients are changed. Imported and exported coefficient files are in text (*.txt) or comma-separated values (*.csv) format.

Bandwidth

Range: 1 kHz to Sample Rate

Default: 1 MHz

Sets the bandwidth for a low-pass filter.

BT

Range: 0.1 to 1.0

Default: 0.5

Sets the BT product of the Gaussian filter.

Length(symbol)

Range: 1 to 1000

Default: 32

Sets the length of the filter in symbols.

Add Segment

Choices: Data Segment | Idle Segment

Adds a segment row to the end of the segment table. Choose between data and idle segments.

Remove Segment

Removes the selected segment row from the segment table.

Move Up

Moves the selected segment row up one position in the segment table.

Move Down

Moves the selected segment row down one position in the segment table.

Name

Sets the name of the segment. Click on the name to edit.

Type

Displays the segment type: DATA or IDLE.

Number of Symbols

Range: 1 to 100000

Default: 1000

Sets the length of the segment in number of modulated symbols. The total number of symbols should be greater than the length of filter.

Payload

Choices: PN9 | PN15 | PN23 | Custom Bit Pattern | User File

Default: PN9

Opens the Closed Data Setup editor to configure payload bits.You can also load, save, and create custom bit patterns.

Constellation

Choices: BPSK | QPSK | 8PSK | 16QAM | 32QAM | 64QAM | 128QAM | 256QAM | 512QAM | 1024QAM | 2048QAM | 4096QAM | User defined

Default: 16QAM

Displays the modulation type for the segment. Click the cell to open the Constellation Setting window where you can customize the consellation.

Phase Rotation

Range: 0 to 360

Default: 0

Set an additional phase rotation applied to the constellation for the segment. To view the phase rotation, you can check the Show Rotation checkbox in the Constellation Setting window.

Shift

Enable or disable shift for phase rotation. When enabled, the phase rotation is only applied to the odd symbol. For example: pi/2 shift BPSK, pi/4 shift QPSK. When shift is enabled, differential and offset are disabled and set to false. When differential or offset is enabled, shift is disabled and set to false.

Bits Per Symbol

Displays the number of bits contained in one modulated symbol.

Differential

Enable or disable the differential encoding for the segment. This can be enabled only for BPSK, QPSK, and 8PSK constellations. Differential and Offset modes cannot be enabled simultaneously.

Offset

Enable or disable IQ offset by half symbol time. This can only be enabled for a QPSK constellation. Differential and Offset modes cannot be enabled simultaneously.