Hello everyone, I tried multiplying the signal with a complex conjugate of itself and then taking a moving average. The log10 is taken to convert to dB. I also used Probe signal and function signal to get my signal power value as a variable. Yet the value of my variable is not changing (it's always the default value). What did I do wrong? Can anyone help me please?
You will find my flowgraph attached. Thank you all for your help. Best regards Rachida Le jeu. 18 nov. 2021 à 17:59, Marcus Müller <muel...@kit.edu> a écrit : > Hi Martin, > > RSSI is "even worse", because it's not universally defined – some > standards define it, > others don't, and what any given device displays as RSSI can be pretty > arbitrary. For > example, IEEE802.11 (so, WLAN/wifi) does not say an RSSI is directly > related to a received > power in watts. > > 4G/LTE introduces a whole set of signal quality metrics for the actual > operation (not for > displaying), so that there's no single number to deal with. Which is fair > - your phone > doesn't just do "one" transmission mode, it has several, with different > modulation and > error correction schemes, and it makes a big difference whether a channel > is mediocre > right now and expected to stay that way, or good but expected to vary a > lot over time. So > a single number can't do the complex situation a receiver is in any > justice, simply > because there's no single requirement: is it more important to the user > that they can > download high speed bursts of website data, or that they have a relatively > constant medium > streaming bandwidth, or a really highly guaranteed minimum data rate? What > about latency? > What about power efficiency? All these are things that are different in > "hardness" in > different scenarios. > In short: the bars at the top right of your phone screen, they're there > for decoration, > are typically updated in a very slow/smoothed out manner, the same applies > to information > like "signal strength -82 dB 60 asu" (phones literally say "asu", that > stands for > "arbitrary strength unit", and while it *is* defined by standards, guess > how consistent > phone implementations of something called "arbitrary" are). > Wireless mobile channels change a couple hundred times a second at modest > speeds of > movement, to which the phone and network need to react; what would a > human-visible > indicator even do with that much information? > > Whenever I see an RSSI number, I interpret it as "An estimate of how well > this receiver > will work in this RX scenario, measured in something that the developers > found easy to > implement, and marketing thought it might appease the user hunting for > best conditions". > > That's not to say a received signal strength indicator is always useless – > but it often > needs to come with a big footnote that defines what it actually tells you, > and what "good" > RSSI actually means, operationally. Still, it's often a better idea to > estimate e.g. the > "cleanliness" of your signal's constellation and call it RSSI than just > looking at RX > power – for example, we're very often in interference-limited scenarios, > so high RX power > is given through either the signal you want to receive – or the sum of > signals you don't. > > In that way, RSSI is "much better" than actual receive power: Your > receiver doesn't > /actually/ work better due to a higher RX power, it works better with a > higher SNR! So, > estimate the SNR from the signal you're receiving; then you get a ratio of > "power in stuff > my receiver needs to know" to "power that disturbs my receiver", and that > can be done > without external calibration. > > Best regards, > Marcus > > On 18.11.21 13:48, Martin Spears wrote: > > This is good to know. After reading this I was going to ask a similar > question about RSSI. > > I will look further into this as well > > > > Get Outlook for Android <https://aka.ms/AAb9ysg> > > > ------------------------------------------------------------------------------------------ > > *From:* Discuss-gnuradio <discuss-gnuradio-bounces+mspears= > icmt...@gnu.org> on behalf of > > Marcus Müller <mmuel...@gnuradio.org> > > *Sent:* Thursday, November 18, 2021 7:37:08 AM > > *To:* discuss-gnuradio@gnu.org <discuss-gnuradio@gnu.org> > > *Subject:* Re: Is there a Gnu Radio block to compute the power of a > signal? > > That's almost certainly not an answer to the question you're posing, > namely "How do I > > measure the power of a specific class of signals". > > A function probe is just a method of getting some data out of a > flowgraph, and it's almost > > never the appropriate solution (function probes are really more for > debugging, or very > > sporadically/randomly updated GUIs and such, not for signal processing). > > > > First of all, it's important to note that basically none of the SDRs > you'd attach to GNU > > Radio come calibrated by default – so the numbers you see in GNU Radio > are only > > proportional to some amplitude of electrical field. So, digital powers > are only > > proportional to the powers on the air, but can easily be calculated > taking the squared > > magnitude of your complex samples. > > > > Best regards, > > Marcus > > > > On 18.11.21 11:45, Rachida SAROUI wrote: > >> Thank you very much! > >> > >> Le jeu. 18 nov. 2021 à 11:40, Van-Dung PHAM <dungdk...@gmail.com > >> <mailto:dungdk...@gmail.com <mailto:dungdk...@gmail.com>>> a écrit : > >> > >> Hi, you can use the Function Probe in GNU Radio to measure the > Power in dBm > >> > >> Vào Th 5, 18 thg 11, 2021 vào lúc 11:23 Rachida SAROUI < > rachidasar...@gmail.com > >> <mailto:rachidasar...@gmail.com <mailto:rachidasar...@gmail.com>>> > đã viết: > >> > >> Hello everyone, > >> > >> I'm looking for a gnuradio block or a method to determine the > power of a received > >> LORA signal from an arduino. Can anyone help me please? > >> > >> Thank you > >> > >> > >> > >> -- > >> > ----------------------------------------------------------------------- > >> Van-Dung,PHAM > >> > > > >
RX_USRP.pdf
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