Help! Pros & Cons: sub-GHz vs 2.4GHz

Hi,

Very short, the 2.4 GHz band may be used world wide while the sub-1 GHz bands are more region specific. As a result, the 2.4 GHz band is more crowded and you will get more interference. The antenna solutions for the 2.4 GHz are normally smaller than for the sub-1GHz. The range for the lower frequency bands are however better than for the 2.4 GHz band solutions, the max allowed output power also differs.

What kind of application are you making? What range do you need for your application?

Hi CHS,

Thanks for your reply.

My application involves upgrading an old system. The system consists of 18 slaves and one master communicating over RS485. This is mainly for indication of parameters at a remote display panel, no control action is required.  Distance between two slaves is approx 10m, while the master is located in a different building 100m away.

What would you suggest ?

Thanks again,

JayantD

Hi,

Does TI have a Teaching ROM for low power RF & Wireless connectivity ?

Regards,

JayantD

Hi,

Now I do not know the environment where you will place your application, how much data you will need to send and how often (higher datarate=>larger RX filter bandwidth => shorter link budget due to decreased sensitivity), but given that you will need a 100m within different buildings, I would go for  a sub-1 GHz solution. The lower the freq, the better range given the same antenna performance.

Charlotte

For more official trainings other than all the blogs, forum posts, design and application notes and datasheets and user guides that is available on web, I would reccommend that you contact your local sales representatives and ask them if there will be any Tech Days in your area soon that you can attend.

Charlotte

Hi,

Recommend to perform some field test in your environment with the kits that are available. Agree that sub 1GHz is the best option and would start to evaluate your application with 868 MHz. By performing the field tests with the kits then you can quickly determine the output power required within the wanted coverage area. Tx unit can be positioned on side of the building and the Rx unit can be moved around the building. Measuring the RSSI level will give a strong indiciation on your system performance that will be required to cover the area.

A rough range estimation can only be stated for line-of-sight transmission since within a building the range will be dependent on the material between the two units. The walls could be made of MDF material or be re-enforced concrete.  

Take a look at the following kits for your field tests:

Performance Radio (CC1120): http://www.ti.com/tool/cc1120dk

CC111x: http://www.ti.com/tool/cc1101dk868-915

Regards,

   Richard.

Hi Charlotte,

The slave units' data gets refreshed every 100ms, but the master unit just displays and stores it in memory for further analysis, plotting etc. Each packet (per slave unit) is 24 bytes and the display refresh rate at the master can be as slow as 5 sec.

So i will go ahead with the sub-1 GHz option.

Thanks,

Jayant

Edit:

TI Asia directed me to the forum, ref. SR#1-754032208, NA

Richard Wallace said:

Hi,

Recommend to perform some field test in your environment with the kits that are available. Agree that sub 1GHz is the best option and would start to evaluate your application with 868 MHz. By performing the field tests with the kits then you can quickly determine the output power required within the wanted coverage area. Tx unit can be positioned on side of the building and the Rx unit can be moved around the building. Measuring the RSSI level will give a strong indiciation on your system performance that will be required to cover the area.

A rough range estimation can only be stated for line-of-sight transmission since within a building the range will be dependent on the material between the two units. The walls could be made of MDF material or be re-enforced concrete.  

Take a look at the following kits for your field tests:

Performance Radio (CC1120): http://www.ti.com/tool/cc1120dk

CC111x: http://www.ti.com/tool/cc1101dk868-915

Regards,

   Richard.

Thanks, Richard !

The "Verify Answer" button seems to have vanished!

Hi,

Just note that if you are to send data from each node every 100ms, depending on the data rate you use, you will limit the number of node that you can have in your system to avoid collisions of the data from the different nodes. I am not an expert on protocols, but how to best solve is something that must be considered.

Charlotte

Lost your last post, but it looked feasible yes, depending on how you synchronize your nodes. I recommend you take a look at information regarding simpliciTI, see http://www.ti.com/tool/simpliciti.

Charlotte

Hi Charlotte,

I deleted the post because a colleague objected. Was trying to find a way to send an email..

Anyway, it's good you had read it !

Thanks,

JayantD