reg RSSI

AMUDHA GUNASEKARAN1

Other Parts Discussed in Thread: Z-STACK, CC2531EMK, CC2531

sir,
I am using CC2530DK with Zstack 2.2a as the code.
I have two router nodes , four end devices and one coordinator ,
there is a packet sniffer used in the work with ubiqua protocol analyzer.
My doubt is the values are shown in the Packet analyzer with RSSI values whether that value can be considered for distance measurement using Path loss exponent formula.
Actually what i have done is i have kept one node with different distance from the coordinator and i have taken the average of 1000 values of RSSI shown in ubiqua. whether this way of considering RSSI is correcct. Please explain me.
My aim is to find the RSSI value for different distance.

over 8 years ago

0 Luis Luna over 8 years ago

Expert 1620 points

Hi Amudha,

You have to know that the RSSI value you are taking in Ubiqua is from the transmitting device to the sniffer, not from the transmitting device to the coordinator. If you want to know the RSSI from the transmitting device to the coordinator, you can take a look at the neighbor table (neighborTable[] in nwk_util.h) or association table (AssociatedDevList[] in assocList.h) in the linkInfo->rxLqi data inside of the structure of the device of interest, in there is an average of the RSSI measured for that device:

rxLqi = (rxLqi + 'rssi of current packet')/2

so have in mind how this value is provided when trying to analyze the data.

On the other hand, I have not done so many tests to relate the RSSI value to distances, but my findings is that it depends on the hardware you use and the orientation of the antennas, it also matters the humidity and the objects in the path, so make sure to have the very same conditions when trying to relate the data (either from coordinator or from sniffer device with Ubiqua).

Hope this helps!

0 AMUDHA GUNASEKARAN1 over 8 years ago in reply to Luis Luna

Genius 3220 points

sir,

Please can u tell me how to write the code over there. I am just having the "extern associated_devices_t AssociatedDevList[];"
sir please tell me how to get the RSSI values. I am seriously new to this.
Don't mistake me.

0 Luis Luna over 8 years ago in reply to AMUDHA GUNASEKARAN1

Expert 1620 points

Hi Amudha,

If you have interest into looking the average RSSI of a neighbor, you may create a function that searches for the entry of this device in the association table and the neighbor table and gives you back the RSSI, and call it whenever you want from the application.

uint8 GetDeviceAvgRSSI(uint8 shortAddr)
{
  associated_devices_t *associated_devices = NULL;
  uint8 i;

  associated_devices = AssocGetWithShort(shortAddr); //We are looking for the device in the assoc list
  if(associated_devices) //if the device we are looking for is found
  {
    return associated_devices->linkInfo.rxLqi; // then return the average RSSI
  }

  for(i = 0; i < MAX_NEIGHBOR_ENTRIES; i++) // If not found in the assoc list, then search for it in the neighbor table
  {
    if(neighborTable[i].neighborAddress == shortAddr) // if the device we are looking for is this one
    { 
      return neighborTable[i].linkInfo.rxLqi; // then return the average RSSI
    }
  }

  return INVALID_RSSI; //If not found in assoc table neither in neighbor table, then return an invalid RSSI value, like 0xFF or 0x00.
}

Hope this helps!

0 AMUDHA GUNASEKARAN1 over 8 years ago in reply to Luis Luna

Genius 3220 points

Sir,
Thank u sir for ur reply.
I am able to get the average of RSSI values, but when i use this to calculate the distance using path loss formula i am not getting correct values , why is it so?

0 YiKai Chen over 8 years ago in reply to AMUDHA GUNASEKARAN1

Guru 735695 points

rxLqi is LQI. Do you convert it to RSSI in dbm?

0 AMUDHA GUNASEKARAN1 over 8 years ago in reply to YiKai Chen

Genius 3220 points

Sir,
I have not converted to RSSI , but it is displaying in Ubiqua Analyser as RSSI only.
Whether this is RSSI value or LxQi value?

0 YiKai Chen over 8 years ago in reply to AMUDHA GUNASEKARAN1

Guru 735695 points

I couldn't understand your description. Can you elaborate?

0 AMUDHA GUNASEKARAN1 over 8 years ago in reply to YiKai Chen

Genius 3220 points

Sir,

I have got four nodes connected in the nework. It is displaying in display of Ubiqua Protocol Analyser of each packet with parameters like RSSI .

U have said that RSSI value is only LQi value.

Because i have said when the value displayed in RSSI parameter is used to calculate the distance it is not giving correct values.

So can u tell me whether the value which is displayed is RSSI parameter or it is LQi. I need to calculate the distance using RSSI value suing the formula RSSI = -(10lognd+A)

But i am not getting the correct value. Please tell me sir , how to find RSSI value by using Zstack 2.2 with Temperature sensor program and how to calculate the distance.

U also please tell me sir whether using distance calculated whether location of a node can be calculated. U might have implemented any sensor network with some front end display where the nodes location will be displayed.

Can u help me to do this sir. I have to get the output.

0 YiKai Chen over 8 years ago in reply to AMUDHA GUNASEKARAN1

Guru 735695 points

If you use Ubiqua Packet Analyzer, it can collect RSSI. If you use Z-STack, it collect LQI.

0 AMUDHA GUNASEKARAN1 over 8 years ago in reply to YiKai Chen

Genius 3220 points

Sir,
Can i have a doubt whether value displayed will be related only to Zstack if i use Ubiqua anlayser sir.

Now what i should do to convert LQI to RSSI sir.

0 AMUDHA GUNASEKARAN1 over 8 years ago in reply to Luis Luna

Genius 3220 points

Hi Luis,
I have checked the zstack coding i am not able to get it , can u tell me exactly where to do it.

0 YiKai Chen over 8 years ago in reply to AMUDHA GUNASEKARAN1

Guru 735695 points

You can get LQI in function afincomingmsg () in AF.c.

0 AMUDHA GUNASEKARAN1 over 8 years ago in reply to Luis Luna

Genius 3220 points

Sir,
Can u tell me exactly in which function this method to be written. Whether this is a method to calculate average RSSI.
If so i should write in Thermostat (coordinator)

0 YiKai Chen over 8 years ago in reply to AMUDHA GUNASEKARAN1

Guru 735695 points

I have told you to get LQI in function afincomingmsg () in AF.c and you can convert LQI to RSSI using formula in
sunmaysky.blogspot.tw/.../conversion-between-rssi-and-lqi-in-z.html

0 AMUDHA GUNASEKARAN1 over 8 years ago in reply to YiKai Chen

Genius 3220 points

thank u sir.
I will check and i will try to get the value

0 YiKai Chen over 8 years ago in reply to AMUDHA GUNASEKARAN1

Guru 735695 points

You are welcome.

0 AMUDHA GUNASEKARAN1 over 8 years ago in reply to YiKai Chen

Genius 3220 points

Sir,

I have this coding in AFincoming Data in thermostat Program of AF.c
static void afBuildMSGIncoming( aps_FrameFormat_t *aff, endPointDesc_t *epDesc,
zAddrType_t *SrcAddress, uint16 SrcPanId, NLDE_Signal_t *sig,
uint8 nwkSeqNum, uint8 SecurityUse, uint32 timestamp, uint8 radius )
{
afIncomingMSGPacket_t *MSGpkt;
const uint8 len = sizeof( afIncomingMSGPacket_t ) + aff->asduLength;
uint8 *asdu = aff->asdu;
MSGpkt = (afIncomingMSGPacket_t *)osal_msg_allocate( len );

if ( MSGpkt == NULL )
{
return;
}

MSGpkt->hdr.event = AF_INCOMING_MSG_CMD;
MSGpkt->groupId = aff->GroupID;
MSGpkt->clusterId = aff->ClusterID;
afCopyAddress( &MSGpkt->srcAddr, SrcAddress );
MSGpkt->srcAddr.endPoint = aff->SrcEndPoint;
MSGpkt->endPoint = epDesc->endPoint;
MSGpkt->wasBroadcast = aff->wasBroadcast;
MSGpkt->LinkQuality = sig->LinkQuality;
MSGpkt->correlation = sig->correlation;
MSGpkt->rssi = sig->rssi;
MSGpkt->SecurityUse = SecurityUse;
MSGpkt->timestamp = timestamp;
MSGpkt->nwkSeqNum = nwkSeqNum;
MSGpkt->macSrcAddr = aff->macSrcAddr;
MSGpkt->macDestAddr = aff->macDestAddr;
MSGpkt->srcAddr.panId = SrcPanId;
MSGpkt->cmd.TransSeqNumber = 0;
MSGpkt->cmd.DataLength = aff->asduLength;
MSGpkt->radius = radius;

if ( MSGpkt->cmd.DataLength )
{
MSGpkt->cmd.Data = (uint8 *)(MSGpkt + 1);
osal_memcpy( MSGpkt->cmd.Data, asdu, MSGpkt->cmd.DataLength );
}
else
{
MSGpkt->cmd.Data = NULL;
}

#if defined ( MT_AF_CB_FUNC )
// If ZDO or SAPI have registered for this endpoint, dont intercept it here
if (AFCB_CHECK(CB_ID_AF_DATA_IND, *(epDesc->task_id)))
{
MT_AfIncomingMsg( (void *)MSGpkt );
// Release the memory.
osal_msg_deallocate( (void *)MSGpkt );
}
else
#endif
{
// Send message through task message.
osal_msg_send( *(epDesc->task_id), (uint8 *)MSGpkt );
}
}

I am able to see in the code sig->LinkQuality and sig->rssi , sir after this what to do.

0 YiKai Chen over 8 years ago in reply to AMUDHA GUNASEKARAN1

Guru 735695 points

You can convert sig->LinkQuality to RSSI by the formula in sunmaysky.blogspot.tw/.../conversion-between-rssi-and-lqi-in-z.html

0 AMUDHA GUNASEKARAN1 over 8 years ago in reply to YiKai Chen

Genius 3220 points

Sir,
I got the formula, but i have a doubt if i just write the code there and just load into my node whether it will display the RSSI value in Sniffer sir.

0 YiKai Chen over 8 years ago in reply to AMUDHA GUNASEKARAN1

Guru 735695 points

It won't display on sniffer. I couldn't understand your intention. Can you elaborate?

0 AMUDHA GUNASEKARAN1 over 8 years ago in reply to YiKai Chen

Genius 3220 points

Yikai sir,
I have done manually the calculation and got the value of RSSI as when lqi is -30 as -100, whether it will be correct sir. I think so i am doing some mistake in that formula.
Similarly u said the value which is displayed in Packet sniffer is LQI , i need this RSSI to be displayed . Whether it is possible.

0 YiKai Chen over 8 years ago in reply to AMUDHA GUNASEKARAN1

Guru 735695 points

I couldn't understand you r descriptions. Can you elaborate?

0 AMUDHA GUNASEKARAN1 over 8 years ago in reply to YiKai Chen

Genius 3220 points

Sir,
As per the discussion before , u have said that the value displayed in packet sniffer is lqi. u asked to calculate RSSI using the formula as specified by SunMay Sky.
So i just calculated by using the formula , smaple value what i got lqi = -30. When this value is used i got the value as -100 in the formula.
I am asking whether this value what i got -100 is correct for lqi (-30).
That is what i asked in the previous reply.

0 YiKai Chen over 8 years ago in reply to AMUDHA GUNASEKARAN1

Guru 735695 points

THe data type of LQI is uint8 so the range of LQI is between 0 to 255. I don't know why you have LQI=-30?!

0 AMUDHA GUNASEKARAN1 over 8 years ago in reply to YiKai Chen

Genius 3220 points

11.7.2016 when waveshare end device attached.txt

0 AMUDHA GUNASEKARAN1 over 8 years ago in reply to YiKai Chen

Genius 3220 points

Sir,

I am attaching the text file what i got when nodes connected. There i have got only in negative, but it is displayed as RSSI.
But in the previous discussion it is said that it is not RSSI value but it is LQI, so i said like that.

0 YiKai Chen over 8 years ago in reply to AMUDHA GUNASEKARAN1

Guru 735695 points

In Ubiqua, it's RSSI. In Z-Stack, you have to read LQI from AFIncomingMsg and convert it to RSSI.

0 AMUDHA GUNASEKARAN1 over 8 years ago in reply to YiKai Chen

Genius 3220 points

Sir,
What i am getting as a value(-30) in the field of RSSI in Ubiqua is what actually sir?

0 YiKai Chen over 8 years ago in reply to AMUDHA GUNASEKARAN1

Guru 735695 points

It means the received package is -30 dbm at the location of CC2531EMK connecting to Ubiqua.

0 AMUDHA GUNASEKARAN1 over 8 years ago in reply to YiKai Chen

Genius 3220 points

Sir,

It means the received package is -30 dbm at the location of CC2531EMK connecting to Ubiqua.!!!

Please elaborate i dont get you sir. CC2531 is the one where packet sniffer is been coded.

0 YiKai Chen over 8 years ago in reply to AMUDHA GUNASEKARAN1

Guru 735695 points

Ubiqua shows received signal strength from CC2531EMK so what RSSI value you see on Ubiqua is sensed from where your CC2531EMK is.

0 AMUDHA GUNASEKARAN1 over 8 years ago in reply to YiKai Chen

Genius 3220 points

Sir,
Then what i should do , to get the RSSI value been displayed from my nodes.
Sorry sir, u have said before that using lqi from AFincomingmessage u can convert to RSSI,
If i do that also how can i make the content to be displayed on my laptop sir.
Please dont mistake me sir. I am afraid if i do anything on my node , if it is making any error i will be finding difficult to fix it, so only i am asking silly questions.
If u have done any User interface to display all these details please share to me sir.
I will be so thankful to you.
Thanks in Advance Sir.

0 YiKai Chen over 8 years ago in reply to AMUDHA GUNASEKARAN1

Guru 735695 points

I am confused by your descriptions and questions. I suggest you to elaborate your issue or question using a diagram so I might be able to know exactly what you want to do.

0 AMUDHA GUNASEKARAN1 over 8 years ago in reply to YiKai Chen

Genius 3220 points

Sir,

I have got RSSI value in Ubiqua as -30dbm , u said it is the received packet strength. My question is whether the value what i have got -30 dbm is correct sir.
That is what will be the range of RSSI values for nodes in sensor network.
U said the range for LQI is from 0 to 255. Likewise what will be the range for RSSI in sensor network. Please tell sir.

0 YiKai Chen over 8 years ago in reply to AMUDHA GUNASEKARAN1

Guru 735695 points

According to the formula given in sunmaysky.blogspot.tw/.../conversion-between-rssi-and-lqi-in-z.html, RSSI would be between -87 dbm (LQI=0) and 10 dbm (LQI=255).

0 AMUDHA GUNASEKARAN1 over 8 years ago in reply to YiKai Chen

Genius 3220 points

Hi sir,
Thank u sir.
If LQI value is 255 the it indicates the link quality is good sir.

0 YiKai Chen over 8 years ago in reply to AMUDHA GUNASEKARAN1

Guru 735695 points

Yes, LQI=255 means the link quality is best.

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