CC1310: Jamming Detection

Hi Leonid

Not sure I understand the question. The radio must be in RX mode to be able to read the RSSI. Are you asking about what happens if the RF core is in the middle of receiving a packet when you issue the CMD_GET_RSSI?

Siri

Hi Siri,
I know that if radio is NOT in Rx mode, so we need sent RX_TEST command and after that issue the CMD_GET_RSSI command.
So if radio IS in Rx mode we can send CMD_GET_RSSI command any time.
And yes, what happens if the RF core is in the middle of receiving a packet when you issue the CMD_GET_RSSI?
BR
Leonid

Hi Leonid

As long as the radio is in RX you can read the RSSI. The RSSI will freeze on sync found so if you are reading the RSSI throughout the packet, the RSSI will not change. Please note that if you are running high speed mode, the RF core will be fully occupied receiving data after sync found, so that you if you try to read the RSSI you will not be able to before the packet is received.

BR

Siri

Hi Siri,

thanks for answer.

Q1: What is the high speed mode?

Q2: What does it means if you try to read the RSSI you will not be able to before the packet is received? 

       Command will not return  before the packet is received? 

BR Leonid

      

        

    

      

Hi Leonid

HSM is our 4 mbps mode. Settings are available in the PER test. I think that the command will not return before you have receive the current packet, but I need to doublecheck this. The person I need to talk to is out of office this week, so I need to come back to you on this one.

BR

Siri

Hi,

how long does it takes to read rssi, when RF in RX mode?
BR
Leonid

Hi Leonid

Unfortunately we do not have any numbers for this. The time will vary depending on whether you are receiving a packet or not. The fastest will be if the radio is in RX but are not receiving a packet. If it is receiving a packet when you want to read the RSSI, the time it takes for the RSSI command to return will depend on data rate.

BR

Siri

Hi Siri,
Data rate is 50000 bps
BR
Leonid

We have done some measurements and I think that was for 50 kbps. There the CMD_GET_RSSI took ~25 us if the radio was not in packet reception when the command was issues. Please note that these are numbers pulled from you a few measurements on a couple of devices.
BR
Siri

And if radio IS in packet reception mode?
BR
Leonid

Hi Leonid

We do not have any number for this as this will vary more. When submitting a CMD_GET_RSSI command, this command will be serviced with a lower priority than the ongoing CMD_PROP_RX.

There are internal FIFOs in the modem that are written/read during packet reception. The GET_RSSI_CMD would be executed in between reading/writing to these FIFOs. The time it takes to read/write depends on data rate, and since we do not know where in this process we are when trying to get the RSSI, it is hard to measure the time for this.

Can I ask you about your use case and why this timing info is necessary? If I know what you are trying to achieve, it is easier give advice.

 

BR Siri

Thanks for answer Siri.

Our use case is as following:

- RF always in RX mode.
- once in a second we measure the RSSI for Jamming Detection .
- packet length us about 28 bytes
- Data Rate is 50000 bps

BR
Leonid

Ok. I cannot see that the additional time the CMD_GET_RSSI would use in packet reception should cause any problems to such a use scenario.
BR
Siri