MC7455 and !sarbackoff command


#1

We are looking to reduce the TX power of MC7455 when it gets too hot in our application.

The only commands I see for this are !maxpwr and !sarbackoff.

!maxpwr limits the max Tx to 20dBm, and we would like to set it lower.

!sarbackoff seems to allow this with an offset. However the command does not seem to be implemented, or I am doing something wrong…

at!entercnd="A710"
OK
at!sarbackoff=?
ERROR

Other SAR related commands, such as !sarstate work as described.

Anyone know about !sarbackoff?


#2

Hello,
This issue is under process to get resolved , meanwhile you can use the following workaround.
AT!SARBACKOFF=?
Where (Network technology)
• 0=WCDMA
• 1=CDMA
• 2=LTE
• 3=GSM
• 4=TD-SCDMA

Thanks & Regards,
Moderator


#3

Thank you.

Just to pass along some more info:

at!sarbackoff=?2
AT!SARBACKOFF= <Technology>, <Band>, <State>, <Backoff offset>
AT!SARBACKOFF? <Technology>, <Band>, <State>

LTE:
Technology     = 2
Band           = (1-5),7,8,9,11,12,13,17,18,19,20,21,25,26,30,38,40,41
State          = 1-8
Backoff Offset: Band    Valid Range
                Band 1: 0 - 93.0
                Band 2: 0 - 93.0
                Band 3: 0 - 93.0
                Band 4: 0 - 93.0
                Band 5: 0 - 93.0
                Band 7: 0 - 92.0
                Band 8: 0 - 93.0
                Band 11: 0 - 93.0
                Band 12: 0 - 93.0
                Band 13: 0 - 93.0
                Band 17: 0 - 93.0
                Band 18: 0 - 93.0
                Band 19: 0 - 93.0
                Band 20: 0 - 93.0
                Band 21: 0 - 93.0
                Band 25: 0 - 93.0
                Band 26: 0 - 93.0
                Band 27: 0 - 93.0
                Band 28: 0 - 93.0
                Band 30: 0 - 92.0
                Band 38: 0 - 93.0
                Band 39: 0 - 93.0
                Band 40: 0 - 93.0
                Band 41: 0 - 92.0

There are many LTE bands listed here that MC7455 does not support.


#4

According to spec sheet, the following bands are supported on MC7455:

B1, B2, B3, B4, B5, B7, B12, B13, B20, B25, B26, B29, B30, B41

The sarbackoff command lists many others, and does not include B29, so we are unable to set an offset on B29.

Am I not understanding something?

Thanks for your help!


#5

Hi: Can someone explain what the SAR backoff states 1-8 mean? 0 = disabled, but no where are states 1-8 explained
Thanks for your help in advance