What is the meaning of the SAT/SIG/TTF GPS status info? When you turn on GPS and some app subscribes for GPS notifications, GPS status info shows up with "SAT", "SIG" and "TTF" info (the last one I know, Time To Fix) but what is the meaning of the first two and what is the meaning of the numbers/symbols (like infinity) shown up next to them?

Update: example of the Android GPS status:

SAT 0/2 | SIG 19/∞ | TTF 27s


The last one means "it took 27s (so far) to acquire GPS signal". I don't know about the first two ones and all those numbers.
Android developers defines the standard parameters 
GPS Status to be used by apps.
Apps can obviously provide more than the minimum information, as in the case of GPS Status &amp; Toolbox, whose help page 
and Android documentation put together help decipher.


SAT 0/2  Number of satellites: GPS in use [+ GLONASS in use] / Total visible. So your phone could detect 2 Satellites but none were used to get a fix (indoors or yet to acquire fix?). This likely corresponds to getMaxSatellites in the documentation.
SIG 19/∞ Average signal to noise ratio (0-40dB). This corresponds to getsnr
in the documentation. The second value is the Dilution of Precision value 
. You were surely indoors  or fix just started, so without fix the error of the position is ∞. Linked wiki says readings having value  >20 should be discarded. 
TTF 27s is getTimeToFirstFix meaning the time required to receive the first fix since the most recent restart of the GPS engine.