Hi Felipe, the LQI value that you get is what the CC2420 radio outputs, and the CC2420 datasheet says: "A correlation value of ~110 indicates a maximum quality frame while a value of ~50 is typically the lowest quality frames detectable by CC2420", so your values seem fine. BTW, you might want to consider (also) RSSI for selecting the parent.
Jan On Wed, Jul 11, 2012 at 12:59 PM, Felipe Cruz Martínez <[email protected]> wrote: > Hi, > > The LQI measurement is a characterization of the strength and/or quality of > a received packet. > The LQI measurement shall be performed for each received packet, and the > result shall be reported to the MAC sublayer using PD-DATA.indication (see > 6.2.1.3 Std. 802.15.4) as an integer ranging from 0x00 to 0xff. The minimum > and maximum LQI values (0x00 and 0xff) should be associated with the lowest > and highest quality compliant signals detectable by the receiver, and LQI > values in between should be uniformly distributed between these two limits. > > I’ve just done a little ‘test’ program in order to see the best link quality > of the end-devices(micaZ devices) with respect the coordinator of my > network. Imagine a network where there may be multiple coordinator devices > and many more end-devices. I want that each end-device will attempt join to > the coordinator which has the best link quality (nearest). > > The problem is that the link quality varies ONLY between values [100, 108] > –decimal- when all the devices are totally together (distance < 3 cm), > corresponding to [0x64, 0x6C] in hexadecimal. > I don’t know why LQI never reaches the maximum value (0xFFFF). > > I’m using IEEE 802.15.4 TinyOS Implementation (TKN154) whose libs are > located at "/tos/lib/mac/tkn154" and test applications at > "/apps/tests/tkn154" directories. > > Any help will be very appreciate. > > Thanks a lot, > Felipe Cruz. > > _______________________________________________ > Tinyos-help mailing list > [email protected] > https://www.millennium.berkeley.edu/cgi-bin/mailman/listinfo/tinyos-help _______________________________________________ Tinyos-help mailing list [email protected] https://www.millennium.berkeley.edu/cgi-bin/mailman/listinfo/tinyos-help
