WLAN Analysis with Wireshark (Radiotap Header Section, Part 4)

Let's continue our discussion on Radiotap Header Section.

Present Flags Words: this is like a summary information regarding any particular information is presented or not. The underneath diagram is an example regarding this field. Since TSFT and Flags sub-fields are explained in another article, we will continue with other items, especially the ones which are shown "Present"

All of the "Present" items are shown here.

Rate (or Data Rate): deals with TX/RX data rate. According to above diagram, we have 6.0 Mb/s. MCS rates (used on 802.11n/HT channels) have the high bit set and the (Modulation and Coding Scheme) MCS in the low 7 bits.
The Wireshark display filter of Data rate (Mb/s) is "radiotap.datarate" where we are able to see 9 or 24 Mb/s in other frames, from the same capture file.

Channel: describes Tx/Rx frequency in MHz. We have 5260 (5 GHz spectrum channel) here.
The Wirehark display filter of Channel frequency is radiotap.channel.freq, where we have seen a fixed 5260 in this capture file.

Antenna Signal: RF signal power at the antenna. The RF signal power at the antenna is described in decibels difference from 1mW. The following diagram shows different Antenna signal being collected from this capture file, in a range of 29dBm ~ 82 dBm.

Question: Out of the same data rate, 6 Mb/s, as an example, are you expecting the same Antenna signal from the following diagram?

Antenna Noise: refers to RF noise power at the antenna. The Antenna noise should remain the same, despite the constant changes on Antenna signal. The below diagram should justify this statement.

Antenna: Contains a single unsigned 8-bit value to declare which antenna was used to transmit or receive the frame. The primary antenna has the lowest number, 1, as stated in our example.
The value of zero may be seen here, it means means antenna selection is left to the device. The writer used "radiotap.antenna" display filter to generate below diagram.