Question

How do I select specific bands on my Telit module?

Solution

The AT command AT#BND can be used to select what specific GSM, UMTS and LTE bands that you want to be active on your module.



If you are experiencing poor DL or UL speeds, one solutions may be to only select the bands that you know are available, which can increase the transfer speeds.





When entering AT#BND? it will return a reply looking like (for example):

AT#BND?

#BND: 0,18,A7E0BB0F38DF,42 (for Generic)

OK



(Please note that the following examples are when using a LM960A18)



The "0" is referring to GSM bands, "18" to UMTS bands, "A7E0BB0F38DF" to LTE bands and "42" to LTE extended bands.



Starting at the GSM band (at chapter "Select Band - #BND" in the AT command reference manual) we can see that 0 corresponds to "GSM 900MHz + DCS 1800MHz (default value depending on module)"



In the same chapter we can read that 18 corresponds to 2100MHz (FDD I) + 1900MHz (FDD II) + 1700MHz (FDD IV) +

850MHz (FDD V) + 900MHz (FDD VIII) + JAPAN1800(FDD IX) + JAPAN800(FDD XIX) (default value depending on product)"



Now for LTE, which is probably what is a little tricky to understand. If we start the Windows Calculator and change to Programmer mode. If you copy the "A7E0BB0F38DF" into the calculator window it should convert it to binary.

HEX: A7E0 BB0F 38DF

BIN: 1010 0111 1110 0000 1011 1011 0000 1111 0011 1000 1101 1111



If you look at the line of BIN above you can see what band are active (1) and which are not (0). Looking from right to left, the first bit corresponds to B1, second bit to B2, third bit B3, and so on…



HEX: A7E0 BB0F 38DF

BIN: 1010 0111 1110 0000 1011 1011 0000 1111 0011 1000 1101 1111

Selected bands: B1+B2+B3+B4+B5+B7+B8+B12+B13+B14+B17+B18+B19+B20+B25+B26+B28+B29+B30+B32+B38+B39+B40+B41+B42+B43+B46+B48



So if I, for example, only want the GSM bands "GSM 900MHz + DCS 1800MHz", the UMTS band "1900MHz (FDD II)" and LTE bands "B1, B4, B7, B28" I would enter the following:



AT#BND=0,1,8000049



Since the first "0" corresponds to "GSM 900MHz + DCS 1800MHz", the "1" corresponds to "1900MHz (FDD II)" and lastly "8000049" corresponds to B1, B4, B7 and B28 as shown below:



Bands: B1, B4, B7, B28

Binary: 1000 0000 0000 0000 0000 0100 1001

Hexadecimal: 800 0049





For further information please take a look at the AT command user guide available on the product's specific page under "technical documentation", which is available for download once logged in.