Hi, I would like to add some additional insights I gained while working on my bachelor thesis (which of course used batman :D ). The dBm you see is the power at which packets are received (Prx). The value of Prx depends on a lot of factors, primarily distance and interferrence caused by re/deflections [1]. There is a minimum Prx at which the signal must arrive in order for your Wi-Fi module to be able to see it as a proper signal rather than noise. This minimum, combined with (thermal) noise (N) gives you a signal-to-noise ratio, which should at least be about 15 dB (SNR = Prx - N >= 15). N is usually somewhere around -100 dBm, meaning that a Prx of about -85 dBm is generally the minimum you need for succesful transmissions. Note that these numbers don't take into account any antennae you might be using, these are only really relevant for calculating the Prx. A higher number means the signal is clearer, but that's really all it means. Because the Prx can only be determined if a packet arrives, the number in itself is meaningless without a time reference, which in turn would only indicate when the last packet was received. Like Simon said, the transmission quality batman-adv returns is based on the probability of packets arriving properly on the other side of the Wi-Fi link. Batman-adv uses counters to determine how many packets were lost and as a result gives a more informative view of how well the link behaves. Because the counters are based on packet reception, this means the Prx also has to be above the minimum. In summary: high dBm = the things that are received, are received very clearly high TQ = nearly everything you send is received. High chance of proper reception => less retransmissions => higher throughput => happy you. [1]: http://en.wikipedia.org/wiki/Path_loss -- Thijs van Veen dicht(a)operamail.com On Thu, Apr 24, 2014, at 11:48, Simon Wunderlich wrote: -- http://www.fastmail.fm - Choose from over 50 domains or use your own

It depends a bit on the receiver's quality, I've had experiences where the SNR could drop to about 8 and the link would still somewhat work. The thermal noise is mostly intrinsic to how energy relates at a particle level, this is denoted by the Boltzmann constant (k). Further, it depends on the bandwidth (B) used and temperature (T). Nthermal = B * k * T = 20*10^6 Hz (802.11 channel) * 1.38065*10^-23 J/K * 300 K (27 Celsius) ~= 8.28 * 10^-11 This gives the noise in Watts, to change it to dBm (which references miliWatts), you take 10*log10( N * 1000 ) ~= -100. [1] Has a nice table with examples of this noise. In reality, there's more interference than just from the temperature. It's quite probable your receiver adds another 5 dBm to its reported noise to account for this. I also recall from my time working on my thesis that receivers/drivers tend to return a static value for noise, rather than actually measure it. [1]:http://en.wikipedia.org/wiki/Thermal_noise#Noise_power_in_decibels -- Thijs van Veen dicht(a)operamail.com On Thu, Apr 24, 2014, at 14:58, Bastian Bittorf wrote: -- http://www.fastmail.fm - Or how I learned to stop worrying and love email again