em7455 seems stuck on LTE B2

[TheFarm]

Good day to everyone.
I am trying to set up an EM7455 in a Dell Latitude e7470. I purchased a new em7455 for a Dell computer(from amazon). Installed it using the factory antennas(black wire primary, grey wire aux), flashed it with the latest firmware, set the modem to generic, and tossed in a Mint Mobile sim.

Mint Mobile uses 3g bands 2 and 4. And LTE bands 2,4,12,66,71

I locked the modem to only use LTE

I programmed a band set that used the bandwidths that the modem supported and Mint Mobile used so I came up with this.

AT!BAND=10, "Mint Mobile', 0000000002800000,000000000000080A
so that is 3g bands 2 and 4, and lte bands 2, 4, and 12.

When I test with AT!GSTATUS? I get
LTE band= B2
LTE bw: 15Mhz (so only b2's bandwidth?)

when I query AT!BAND? I get
BAND=10, "Mint Mobile', 0000000002800000,000000000000080A


I am only getting 12-16% signal from mint mobile which suggests to me the band is limited to just b2.

Resetting the modem does not make any changes either.

This is my first attempt at tuning a modem like this, but it appears to me that it does accept commands and configurations, but seems stuck on band 2.

I am not sure how to tell if this is a problem on my end or Mint Mobiles end. They claim I should have good service in my area using their LTE checker(B2, B4, and B12 having excellent coverage). Their customer reviews are not great, but they were cheap...

Any help is appreciated

[JimHelms]

Does Mint Mobile not run on the T-Mobile network?

If so, you should also be able to add Band 5 in the mix. The modem will accept it, and will may or may not be used by the carrier.

Unless you have a special need for the 3G, I would also remove it from the mix, at least until I was up and running properly.

I would program those LTE bands and try it:

Code: Select all

AT!BAND=10,"2,4,5,12",0,81A
AT!BAND=10

Once connected, post the stats from:

Code: Select all

AT!GSTATUS?

[TheFarm]

Mint is a T-mobile wholesaler but band 5 is not listed. That said I also cannot get it to change to band 4 or any other individual band for that matter. At least based on AT!GSTATUS? the only returned value is b2. This is the readout no matter what band or bands I try to set the modem to.

!GSTATUS
Current Time: 1213 Temperature: 28
Reset Counter: 2 Mode: ONLINE
System Mode: LTE PS state: Attached
LTE Band: B2 LTE bw: 15MHz
LTE Rx chan: 1025 LTE Tx chan: 19025
LTE CA state: Not Assigned
EMM state: Registered Normal Service
RRC state: RRC Idle
IMS reg state: No Srv

PCC RxM RSSI: -01 RSSP (dBm): -115
PCC RxD RSSI: -78 RSSP (dBm): -112
Tx Power: -- TAC: 2C34 (11316)
SINR (dB): 1.0

The system is running Fedora 30 and I am using the antennas that were installed by the factory.

[TheFarm]

I did try 81A as you suggested but it did not affect anything.

[saw2645]

I don’t have band 71, so I don’t know where it’s hex decimal goes but for my m1 to get 2+4+12+66 here is what I used
AT!band=06,”LTE B2+B4+B12+B66”,0,80a,2

It’s probably just an issue, but I can’t add more than 9 lines, so I can’t use the line 10 like you have.

Can you use AT!band=? To get the current index? That’s where I got the info to figure the syntax for the band lock.

[TheFarm]

AT!band=? returns the band 10 option I created with bands 2, 4, and 12. My modem cannot do band 66.

mmcli -m 0 returns that the modem is using lte bands 2 , 4 and 12 as I had hoped. So perhaps the AT!GSTATUS? does not return all channels it is tuned to?

Is there some way I can tell if the crappy signal I am getting is based on something to do with the modem or the provider?

[yzrmbsg]

What you did with your AT command is to only allow band 2, 4, and 12 to be used. This does not however, have anything to do with what the tower is going to let you use. The band you get...is what the tower tells you to get. You can band lock to a single band 4 or 12 or 4 and 12 to aid in carrier aggregation if the tower allows it, but having any more than 1 band locked, "you get what you get" from the tower. BUT if you lock to any 1 band, and the tower gets congested, you could lose service altogether from the tower.

[CarlsPie]

Hi, I have a similar issue. Reading your posts I have already learned a few things.

I installed it in a Lenovo Thinkpad X230, installed the generic driver, and put in a Google Fi SIM (Which activates on T-Mobile, but can roam on ANY carrier).

Question 1: How do I update the firmware.

Question 2: How do I connect to the EM7455 to send it commands?

My Thinkpad X230 is also apparently stuck on band 2 with generally poor service. I can turn on/off certain bands within Windows by using a third party application I paid $15 for called "EM7455 Control Panel". I haven't done much testing but I did manage to get service on Band 4 when disabling Band 2. I need to do more testing but my ultimate goal is to have decent service without manually testing and switching bands... I know you said you get the band the tower gives you, but how doe Cell phones seem to intelligently connect to the best bands? Is there simply a hardware limitation ensuring that service and connectivity will almost always be poor with the EM7455?

[BillA]

Mint is a T-mobile wholesaler but band 5 is not listed. That said I also cannot get it to change to band 4 or any other individual band for that matter. At least based on AT!GSTATUS? the only returned value is b2. This is the readout no matter what band or bands I try to set the modem to.

The reason why Mint doesn't list band 5, is because Tmobile themselves only use band 5 for roaming on partner carriers in a few places around the country. So while adding it won't hurt, chances are it will not be used by your local tower. Your EM7455/MC7455 has the following usable bands only: 2, 4, 5, and 12. Bands 46 (LAA), 66 (band 4 extension), and 71 (600Mhz) are not available even if you try to force them, it simply won't work. The newer EM7511/EM7565 has all those bands except for 71, which is currently only used by Tmobile.

US LTE Bands
*Primary bands
ATT = *2, 4, 5, 12, 14, 17, 29, 30, 46, 66
TMO = 2, *4, 5 (roaming only), 12, 46, 66, 71
VZW = 2, 4, 5, *13, 66
SPR = *25, 26, 41