AWR1843: Chirp verification on spectrum and oscilloscope

baolong jian

Prodigy 20 points

Part Number: AWR1843

Tool/software:

Hi TI expert

Now we are using AWR1843 chip to develop our radar .

We designed a kind of chirp and measured on the spectrum and oscilloscope.

The chirp parameter is listed as below:

Idle Time = 8us
Ramp End Time = 34.6us
slope = 83.7 MHz/us
StartFreq = 77.56GHz
Total sweep bandwidth = 2.89GHz

The bandwidth meausred on the spectrum looks right.

But on the oscilloscope, the test results show that it is not a correct standard chirp.

The signal does not drop to the starting frequecny within the idle time.

Can you help us check if there is any problem?

The oscilloscope is Keysight DSOS404A , and the chirp analysis software is Keysight 89600 VSA

25 days ago

0 Shailesh Joshi 25 days ago

TI__Expert 4060 points

Hello,

Are you probing the TX output for observing this? Note that the TX output will be turned off at the end of the FMCW ramp and it will only start around the start of the next ramp. So, the measurements in between might be unreliable.

Regards,
Shailesh

0 baolong jian 25 days ago in reply to Shailesh Joshi

Prodigy 20 points

Hello,

No probing.

We use the radar target simulator to down convert the 76~81GHz signal to 0.6~5.6GHz.

The down-converted signal is fed to the oscilloscope via cable.

So you mean it is just a matter of measurement ?

0 Shailesh Joshi 24 days ago in reply to baolong jian

TI__Expert 4060 points

It is still not clear to me what part of the AWR1843 device is being measured for the 76-81 GHz signal. Whichever way it is, just wanted to inform you that the device will not transmit out any radiation between the ramps.

Regards,
Shailesh

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AWR1843: Chirp verification on spectrum and oscilloscope