AWR1642: TX output power setting in Config profile

kuowei lin

Part Number: AWR1642

An argument under the profileCfg CLI command that control the output power backoff called "txOutPower".

From SDK document, the description for "txOutPower" is few, there is no unit or....

We found there is one question in forum, too

https://e2e.ti.com/support/sensors-group/sensors/f/sensors-forum/768117/awr1642-output-power-and-antennta-gain/2840011?tisearch=e2e-sitesearch&keymatch=AWR1642%2520txoutpower#2840011

Therefore, we try to set "txOutPower" in different value, for example: 0, 2, 4, 6, 9, 12, 15 etc.

From the result, it seems not the expect we hope if the unit is dB.

For example, Tx output power set as "2" is slightly better than "0"; Tx output power set as "6" just slightly lower than "4".

Below figures shows the test result on each RX (1~4) gain power value by different TX output power.

(Test in chamber environment and distance for radar and corner reflector RCS=10 is 3.2 meters with rotation platform from -105 degree to +105 degree)

over 3 years ago

0 Ishita Kochar over 3 years ago

TI__Mastermind 31680 points

Hello Kuowei,

TX Output Power is expressed in dBm.

Please find some similar threads linked below which help clarify the concept of TX output Power and Output Power Backoff programmability :

AWR1843BOOST: About TxOutPowerBackOffcode - Sensors forum - Sensors - TI E2E support forums

AWR1843: How can I backoff TX power & reduce RX gain? - Sensors forum - Sensors - TI E2E support forums

These will help you understand the concept first. Let me know if you still have any questions/concerns.

Regards,

Ishita

0 kuowei lin over 3 years ago

Prodigy 210 points

If the unit is dBm, it is more reasonable.

Thanks.

0 kuowei lin over 3 years ago in reply to kuowei lin

Prodigy 210 points

From https://e2e.ti.com/support/sensors-group/sensors/f/sensors-forum/1045771/awr1843boost-about-txoutpowerbackoffcode/3869837#3869837

It said that "(Power from transmitting antenna) = 12 --a", 12 is the default backoff "0" = 12dBm.

If I program 15dB backoff, the TX O/P power will be negative i.e. 12-15 = -3dBm

Is this right? The setting unit for txOutPower is dB, but the TX O/P is expressed in dBm.

If above is correct, if I program 3dB backoff, the TX O/P power will be negative i.e. 12-3 = 9dBm, then the received power in RX which I tested should be 3dB difference, but the result is just around 1 dB difference??

0 Ishita Kochar over 3 years ago in reply to kuowei lin

TI__Mastermind 31680 points

Hello Kuowei,

The TX Output power backoff parameter denotes how much the transmit power should be reduced from the maximum.

Hence, if you program the backoff as 15, the total output power will go negative as you said i.e. 12-15 = -3dBm.

If you program backoff as 3, the Tx o/p power = 9dBm (which is positive). Are you comparing this number to the input level at the RX input?

Please see a similar thread which talks about your concern : https://e2e.ti.com/support/sensors-group/sensors/f/sensors-forum/613223/awr1243-how-to-calculate-the-precise-power-on-the-tx-and-rx-pin

Regards,
Ishita

0 kuowei lin over 3 years ago in reply to Ishita Kochar

Prodigy 210 points

The testing parameters we have is to keep the RX gain as 48dB, then change the TX backoff setting from 0 to 15, then we would like to check if we set TX backoff as 1, it should reduce 1dB, and 2 with 2dB reduced as well, and so on.

But from the testing result of receiver power (Calculated from SW) , it seems not the same as we expect.

For example:

Receiver power of TX backoff 0 is almost same as backoff 2. (This is wrong)

Receiver power of TX backoff 2 is larger than backoff 4 around 2 dB. (This is correct)

Receiver power of TX backoff 4 is almost same as backoff 6. (This is wrong)

Would you help to find out the problem?

Thanks a lot.