Hello, all!
Our team is trying to find out the relationship between PER and Received Signal
Strength as well as the relationship between Distance and Received Signal
Strength under DBPSK modulation scheme using two USRP borads. Our test was set
up in a near free space environment, but the result was counterintuitive. Below
lists the result from our test: PER = [7.602%, 0.583%, 0.2317%, 1.095%]; RSSI =
[928.7573, 1296.6, 2386.2, 2587.7] which is the value of
tb.rxpath.probe.level(); distance = [260,240,220,200]. There are two things
confusing me. As can be seen, from 240feet to 220feet, the rssi was almost
doubled, but the PERs were almost the same. For the same 20feet difference in
distance, the PER declined from 7% to 0.5% while the rssi was only increased by
300. Why is there a huge jump in RSSI when distance changed from 240 to 220
compared with the case when distance decreased from 260 to 240, meanwhile the
improvement of PER is not obvious? Why is there a huge
plunge in PER when RSSI was increased only by 300 and distance was changed
from 260feet to 240 feet? Is there any theshold or restriction in the USRP
board? Could anyone tell me the reason for our problems? Thanks a lot!!!
Tianning
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