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Simple IQ file to Tx | Use the SPECTRAN V6 as an IQ Vector Signal Generator

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Attached is the most simple IQ file/data to Tx mission using the SPECTRAN V6 as a vector signal generator:

Simple IQ Vector Signal Generator mission


Simply load your IQ file to the File Reader block and stream the IQ data to the SPECTRAN V6 (Transmitter Mode is set to "Stream" so it will stream the IQ data from the IQ file). Make sure the record frequency is the same as the SPECTRAN V6 frequency, otherwise add an IQ Modulator block.

You can change the output power in the SPECTRAN V6 block under Main- > Transmitter Gain from -100dBm to +10dBm (Default = -20dBm):

Vectior Signal Generator with up to 120MHz RTBW


Uploaded files:

I follow the posts step by step, and connet the Tx signal to the Keysight SA. the V6 500X is work well, but it don't work, no signal output from the Tx port. I am confusing what I make something wrong?

Some ideas:

  1. You don't stream an IQ file
  2. Your output power is to low
  3. No power (our USB power supply or a PD USB 3.1 port) connected to the POWR USB connector
  4. No BOOST cable connected (must have for Tx operation)

Attached a short IQ demo file to play with (200ms long). Make sure to loop it since its quite short.

Uploaded files:
Sofon has reacted to this post.

I connect my devices instead of your attached mission and load my IQ record in the file reader, and then changing any other IQ files, you will see the SPECTRAN V6 Tx just can output the CW signal not the correlative signal from this IQ files. I had tried it again and again.which version of the RTSA-Suite Pro and FPGA version it need implement "IQ File to Tx" block function?

Check the warnings (yellow Tx). Your system does not work.

BTW: You are running Rx and Tx at the same time without boost connection. This can't work.

Sofon has reacted to this post.

Please also note that the Tx input from a file requires an IQ Modulator block as last step if the frequencies do not match from the beginning:

Tx input from a file requires a modulator as last step if the frequencies do not match from the beginning


Adding the IQ Demodulator in addition can reduce the needed Tx bandwidth (if wanted and possible):

Tx input from a file requires a modulator as last step if the frequencies do not match from the beginning

Please try attached mission with the latest RTSA (Build 10340 or higher) which now offers a Time Offset paramater within the File Read block. This should help a lot to work around low power hardware:

The mission looks like this:

IQ file via File Reader to Tx

File Reader:

  • We are reading the IQ demo file over and over again by setting the Time Offset to a quite high 100ms and are activating the Emulate Realtime checkbox.
  • Finally we are setting the Playback Mode to contiguous since the demo file is very short.

IQ Demodulator (optional, can be removed):

  • We are using a small Span Frequency of 1MHz to cut the signal from the wide band and to reduce the data amount.
  • We are reducing the Sample Rate to 10MHz so slow CPUs can handle the data amount.

IQ Modulator:

  • We are moving the frequency from 868MHz to 2440MHz (example).
  • We keep the Span and Sample Rate the same as in the IQ Demodulator.


The original 868MHz Car Key IQ Demo File is now running with 10MHz sample rate at 2440MHz and is transmitted via the SPECTRAN V6 Tx.

Use the SPECTRAN V6 Transmitter Gain slider to adjust the Tx output level.


Mission Settings and Layout:

IQ to Tx mission

Uploaded files:
Sofon has reacted to this post.

As mentioned above make sure to add enough "buffer" via the Time Offset feature and to activate the Emulate Realtime checkbox if you use the File Reader to send IQ data to the Tx:

IQ Streaming

Sofon has reacted to this post.

We have updated the Tx operation.

Please check out the latest missions and documentation here:

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