Precisions about the Radar Fusion GUI and the BGT60TR13C Demo board

[MathieuC]

Hello every one,

I have been trying the BGT60TR13C Demo board with the radar fusion GUI.

I have several questions about the radar fusion GUI.

1) When I configure the Start Frequency to 58 GHz and the End Frequency to 58.3 GHz, I get a spatial resolution of 0.548 m (see screenshot attached) whereas the theoretical spatial resolution is 0.5m. How do you explain the difference ?

2) What is the Receiver Gain exactly (see screenshot attached) ? I have looked in the help contents of the radar fusion GUI application but I could not find any information about this parameter. I could not find any information about this parameter in the datasheet of the radar chip as well. When I tune the parameter "Receiver Gain", what does it change in the BGT60TR13C radar chip ? Is it the gain of an analogic amplifier before the ADC or is it a numerical amplifier applied to raw data ?

3) As we can see, it is possible to tune the Sampling rate. Does the cutoff frequency of the anti-aliasing filter before the ADC change as well  in order to filter all signals above the half of the sampling frequency ? What happends in the radar chip when we tune this parameter ?

Thank you very much in advance for your reply.

[Honey_D · Accepted solution]

Hello @MathieuC ,

1. All the radar parameters are processed and evaluated in terms of chirp. A chirp is a signal whose frequency varies with time and can be depicted as shown below:

As you can see the total bandwidth of the chirp df = ftx_end − ftx_start comprehends the sampling bandwidth Bs = fadc_end−fadc_start , thus the delay is also considered while calculating the range resolution factor, r_res = c / 2Bs, but the total bandwidth of the chirp can also determined by the desired range resolution using the following relations:

2. The receiver gain or IF gain is the amplification factor applied to the  IF signal coming from the RF mixer before it is fed into the ADC.

3. Sampling rate of the ADC used to acquire the samples during a chirp. The duration of a single chirp depends on the number of samples and the sampling rate.

For further detailed explanation on all the parameters please refer to the documentation of the Radar SDK from \radar_sdk\doc

Hope this Helps!

Best Regards

Honey

[Montassar-BR]

Hi @MathieuC,

In fact the shown "Sampling Bandwidth" of 0.3GHz looks wrong... since due to some PLL delays, this would not be really the set bandwidth... this would then impact the calculation of the "Range Resolution"...

We are checking this behaviour of the Radar Fusion GUI, with our DEV team, and will let you know if a bug to be confirmed or not.

Cheers,
Montassar.

[MathieuC]

Thank you very much @Montassar-BR  and @Honey_D  for your replies.

I have other questions about the radar Fusion GUI:

1) When the User Mode "Standard" is set, the Tx power changes when the frequency of the emitted wave changes as shown on the screenshots below

What causes these changes exactly ? Is it the Tx antenna ? Is it the Power amplifier ? How is the Tx1 power value computed by the radar fusion GUI? Is it the EIRP or the electric power at the Tx antenna input?

2) Is there any risk of damaging the radar sensor by setting a high value for the receiver IF Gain ?

Thank you very much in advance for your replies,

Mathieu

[Honey_D]

Hello @MathieuC ,

1) The radar system is designed on the basis of the following equation:

Transmitted power depends on transmitter frequency and antenna gain. For a given amount of transmitted power, the main lobe of the radar antenna beam extends to a greater distance at a given power level with greater concentration of power in narrower beam widths. To increase maximum detection range capabilities, the energy is concentrated into as narrow a beam as is feasible. The beam width is dependent upon the frequency or wavelength of the transmitted energy, antenna design, and the dimensions of the antenna.

2) Receiver IF gain is defined for IF amplifier which amplifies the Intermediate Frequency (IF) signal and  improves the Signal to Noise Ratio at output. Thus, there will be no damage to the Radar while setting the value to maximum available on the Radar Fusion GUI

Hope this answers your questions!

Best Regards,

Honey

[MathieuC]

Hello Honey,

I would like to calculate the link budget of this sensor in order to estimate the maximum detection range.

I need the noise figure of the receiver. Is it possible for you to share this information ?

Also, the gain of an antenna wich has an elevation beamwidth of 65° and an azimut beamwidth of 35° is about 12dBi, which seems a pretty large value for antennae in package (almost the same than a corner antenna)

Can I assume that the gain of the antennae is of 12dBi or is it a wrong value ?

Are you aware of any publications describing  the BGT60TR13C link ?

Thank you very much in advance for your help.

Mathieu

[Honey_D]

Hello @MathieuC ,

All the information regarding the capabilities and features of BGT60TR13C are given in the datasheet (https://www.infineon.com/dgdl/Infineon-BGT60TR13CDataSheet-DataSheet-v01_00-EN.pdf?fileId=8ac78c8c7d... and product page: https://www.infineon.com/cms/en/product/sensor/radar-sensors/radar-sensors-for-iot/60ghz-radar/bgt60... 

For link budget calculation, the parameters required for calculation are given in the datasheet and application note. The gain of antenna is 5 dBi as mentioned in the application note: https://www.infineon.com/dgdl/Infineon-BGT60TR13C_Shield-ApplicationNotes-v02_02-EN.pdf?fileId=8ac78... as well as on the product page.

For further information you may also refer to the documentation included in Radar Development Kit 

Hope this helps!

Best Regards,

Honey

[MathieuC]

Hello Honey,

Thank you for your reply and all these links.

You are right, the antenna gain is in the datasheet, at the end.

Nevertheless, I could not find the receiver noise figure in the documentation (it is not in the datasheet, it is not in the application note neither).

I have read the application note, there is a paragraph about the phase noise, but there is no information about the noise figure of the receiver.

Is it a sensitive information ? Is the Noise Figure of the order of 10dB or rather 20dB?

Thank you in advance for your reply.

Mathieu Chalnot

[Honey_D]

Hello Mathieu,

For further information and documents on BGT60TR13C, a Non-Disclosure Agreement(NDA) is needed.

Best Regards,

Honey

[MathieuC]

Hello,

When I load a JSON configuration, the theoretical max range displayed in the radar fusion GUI is not always correct as shown in the screenshot below:

It looks like the computed value for the theoretical max range is not updated. How to update this value ?

Thank you for your advice.

Mathieu

[Honey_D]

Hello @MathieuC ,

We are also able to reproduce the same issue. A bug is confirmed here, and is shared with the Radar Fusion GUI development team and soon it will be fixed.

Best regards,

Honey