IWR1843: About the Tx output power back-off for tx antennas

Jun Fang

Prodigy 170 points

Part Number: IWR1843

Hi,

I am using txOutPower to decrease out power of Tx antennas, here is the related configuration:

channelCfg 15 1 0

adcCfg 2 1

adcbufCfg -1 0 1 1 1

profileCfg 0 77 916 7 57.14 30 0 70 1 256 5209 0 0 30

by setting txOutPower to 30, I see an obvisous drop of relative power.

Since maxium out power of Tx is about 12dB, the out power of Tx should be 12-30=-18dm. I am wondering if it means the Tx doesn't tranmit any signal? If so, why there are still two detected points in the figure.

Thanks.

over 1 year ago

0 Santosh Krishnan over 1 year ago

TI__Expert 8690 points

Hello.

The TX output power back-off code is 1) not in dB and 2) in decimal notation but from a converted hex number. It is a 24 bit value, with every 8 bits representing the TX backoff for each transmitter. For example, for a 10 dB back off for all 3 transmitters, the hex number would be 0A0A0A, which then converted to decimal is 657930. You can do the same with 30 dB as well. As a result, putting 30 as the parameter value in profileCfg is very close to 0 dB backoff, which is why you are still getting the detected points.

Hope this helps,

Santosh

0 Jun Fang over 1 year ago in reply to Santosh Krishnan

Prodigy 170 points

Because I only use one Tx, so I think 30 is OK.

Set the back-off code to 1973790, which is 0x1E1E1E. The output is the same as the above figure.

So, why there are still some detected points? Thanks.

+1 Santosh Krishnan over 1 year ago in reply to Jun Fang

TI__Expert 8690 points

Hello Jun.

The power on that scale is relative so you won't see a major drop off even with a reduction in transmit power. Also, why are you not trying to detect points?

Sincerely,

Santosh

0 Jun Fang over 1 year ago in reply to Santosh Krishnan

Prodigy 170 points

OK. I just want to confirm that the transmit power is actually decreased.

Thanks.

Sensors

Sensors forum

IWR1843: About the Tx output power back-off for tx antennas