+KCELL=1 Signal strength vs $CSQ

Embedded wireless modules HL Series
#1

Hello,

We’re using +KCELL=1 on the HL8548 to get information about neighboring towers. We’re interested in getting the physical channel power for each tower, similar to what we can retrieve with the $CSQ command.

Based on the AT Guide (version 19), GSM towers return RSSI which is an offset of -110 dBm. Is the resulting value equivilent to the physical channel power from $CSQ?

For UMTS towers, $CSQ returns Ec/No in addition to rssi. Is my understanding correct that in order to get physical channel power, we need to do (rssi * 2 - 113) + Ec/No ?

Similarly, for UMTS on KCELL, there is an rscp and ecno value, but they appear to have different ranges than the same in $CSQ. How do we calculate physical channel power from these values in KCELL?

Thank you,
Lennon

1 Like
#2

As an additional observation, I’ve noticed that there are times where $CSQ returns a value just fine, but the rscp value from the KCELL call is defaulted to 255 for all towers (including serving). I see this behavior frequently when signal is low, but still good enough to transmit data via tcp. Is there anything I can do to make sure I get an rscp from KCELL?

#3

Hi Lennon,

To get the rscp, maybe you can try +KNETSCAN(Network Scan)?
AT+COPS=2 //deregister from network
AT+KNETSCAN=1,1 //activate network scan, enable URC
//Wait some seconds to get the URC like below
+KNETSCAN: 2,49,42,64f000,247c,1448,5,48,55,64f000,247c,13ed,5
+KNETSCAN: 2,10663,64f010,a52a,d9fe179,432,19,39,10688,64f010,a52a,d9fe17a,432,14,39
AT+KNETSCAN=0 //deactivate network scan
AT+COPS=0 //auto register to network

#4

So are you saying we shouldn’t be using KCELL? In what situation would we use one versus the other? We’re ultimately using this as part of a location calculation.

Are you able to help with any of the questions in my first post?

Thank you,
Lennon

#5

Matt replied in another thread about the return value on KCell indicating missing data (especially on 2G). Is this related here as well and requiring the +KCELLSCAN?

#6

I have a similar question regarding scanning and XCELL with respect to HL7800. Any comments at this link?
https://forum.sierrawireless.com/t/cellid-cell-locate-geolocation-on-hl7800/19476