RTOS/CC1310: Receiving packet from another frequency

What do you mean by " by ~100dB"?

You are not writing anything about the settings you are using. Normally a out of band signal has to be folded down into the channel to be able to receive it.

Hi TER,

Its my bad. We are using 5kbps Long Range Mode with CC1310/CC2500 compatible whitening mode and broadcasting 869 MHz. Symbol rate: 19.99kBaud, Deviation: 5kHz, RX Filter BW: 49 kHz

We made test with Launchpad. We are broadcasting at 869MHz with 500 ms interval. We listened 869MHz and 864MHz frequencies with twp launchpads. Test result is shown in picture  below. 

As it is observed above, i can receive packets from 864MHz. These packets are transmitting in 869MHz originally. I do not want to receive packets from another frequencyi i just want to receive packets that belongs to my own frequency. How can i prevent to take these packets from another frequencies ?

Regards.

Ramazan 

In the original post you wrote that you received @867 MHz but in the last post you write @864 MHz.

To verify, do you see the same @867 MHz (or other frequencies)?

Hi TER,

In the picture below i listened 867MHz. Again i can receive packet with low rssi.

Regards.

Ramazan

Edit: I attached the right picture. Last picture was wrong.

This is most likely caused by a combination of filtering and folding/ mixing.

Since the RF front end is not ideal part of the incoming signal could be folded down to other frequencies. These folded / mixed part will be week but in some cases like you experience you can still receive.

You can avoid this by using address filtering or similar to ensure that you only receive data on the channel you want to listen to.

Hi TER,

Thank you for your answer. We do not want to receive these signals. We can filter these after receiving packet but we do not want receiving.
May be, If we choose frequencies with spesific order we can not receive these packets(ex. f1 = 869MHz, f2 = 873MHz). So, how should we choose frequencies for not receiving packets ?

Regards.

I have to look a bit to see if some frequencies are better than others but why isn't address filtering good enough?

Hi TER,

We are working on low power real time audio streaming devices and we do not want to use our limited bandwidth with unnecessary information. And also, we are dealing with mesh network which requires multicasting. So, we do not have any chance to use address filtering. If you find better frequency couples to use, we will be appreciated.

Regards.
Ramazan

Thank you for the explanation. I haven't had the time to test this, but can you try frequencies that are not a multiple of 2 MHz offset from the center frequency?

Hi TER,

I will try this in upcoming days. If you try before me, you can tell in there. 

Thank you.

Regards

Ramazan

Ramazan,

Can you also test in your setup to receive at e.g. 864.2MHz? This will show whether this is a folding issue and/or if the blocking performance is not good enough for your use case. (~80dB at 5MHz offset for 5kbps SimpleLink Long Range).

Thanks