MC7710 Max Tx power control

IoT Modules MC/EM Series
1

Hi,

I’m to get or set the Tx power with the AT!MAXPWR commands on a MC7710 but they seem not to be recognized.

My MC7710 version (DIP): !GVER: SWI9200X_03.05.24.00ap r5792 carmd-en-10527 2013/05/02 13:35:47

Examples:
->get the LTE B7 power
at!maxpwr?7,2
ERROR

-> query the synthax
AT!MAXPWR=?
ERROR

->set the LTE B7 power to 10dBm
at!maxpwr=7,2,10
ERROR

Can you explain me why that does not work ?

Thanks !

Eric

2

Hi Eric,

Welcome to the forum :slight_smile:

!MAXPWR command is protected command, please first use !ENTERCND command to enter correct password before you can access to the !MAXPWR command.

By the way, max 10dBm maybe not possible, here’s return for “AT!MAXPWR=?”

AT!MAXPWR=?
WCDMA: ,and LTE:
AT!MAXPWR= <Band>, <Technology>, <Max Tx Value>
AT!MAXPWR? <Band>, <Technology>

Band           = <0-65>
Technology     = 0: WCDMA
                 2: LTE
Max Tx Value   = <20-24.5>

OK

Thx

3

Thanks Lotam for your very fast answer. I’ll try this solution asap…

Isn’t it definitely possible to reduce the Tx power below 20dBm ? In my application, I would need to set it below this value (despite 10dBm may be to low).

Besides this, I got my MC7710 card as spare parts. Is the default passwd “OEM password” ?

Eric

4

I think using !SARBACKOFF would yield the expected results. It allows specifying offsets of 0 … >=90 dB for WCDMA and LTE.

Offsets for GSM are only 0 db or up to 8dB depending on number of Slots, but I think this is fine as regulation (at least in Germany) allows significantly higher TX powers for GSM.

5

Hi Stephan,

thanks, I also saw this command but I do not really understant the “state” parameter and did not find (yet) any documentation about it and the relationship with the Maxpower.

Would you have information on this ?

Best regards
Eric

6

Hi Eric,

SAR backoff is to make additional control to the TX power when the mobile device is close to human body as per the regulation requirement, please refer to specific absorption rate Wiki for more details.
http://en.wikipedia.org/wiki/Specific_absorption_rate

So, the “state” allow you to define the backoff offset required in different situation, similar to profiles on cell phone we can first define the setting and then we can select the exact profiles thus more efficient and flexible.
For sure you can use and take care only one state, e.g. state “1”, in your application.

The relationship is like, for example, max power was defined 20dBm, but you want to use 10dBm then you can set additional offset.

Hope it helps.