Signal Guide

Service Description Selection WLAN

Here you will find information about the selected service, along with measurement examples.

WLAN Theory & Details
Communication
Typical Frequency Range:

2.4 – 2.5 GHz
5.15 – 5.35 GHz
5.47 – 5.725 GHz (not permitted in all countries)

General:

WLAN is used for wireless connection of computers and devices over short to medium distances. Numerous variants have been standardized by IEEE.

Modulation: OFDM, FHSS, DSSS, BPSK, QPSK, 16-QAM, 64-QAM

The numerous standards mean that there are many permitted modulation types. The following are frequently used: FHSS (frequency hopping spread spectrum) in older systems with 1 – 2 Mbit/s capacity, DSSS (direct sequence spread spectrum) with up to 54 Mbit/s capacity, and COFDM (coded orthogonal frequency division multiplex).

WLAN Measurement Examples
Spectrum
WLAN activity in the ISM band 2.4 – 2.5 GHz. The spectrum shows three WLAN transmissions with DSSS modulation. The bell-shaped curves with central drop are typical. Displayed in »Stitched Mode«, so there are time gaps in the record. However, storage of the maximum values retains all the events captured during the measurement time
Spectrogram
Same frequency range as for Spectrum. The device delivers a “snapshot” every 22 ms. The WLAN does not show high data throughput – only in the millisecond range. Capture is partial because of »Stitched Mode« and the short burst duration
HiRes Spectrogram Full
The triggered display shows three bursts. The first and second (trigger time T) are practically merged together. The width of the frequency range shown is 25.6 MHz with no time gaps in the capture.
HiRes Spectrogram Zoom
Section of the HiRes Spectrogram Full display. The width of the frequency range shown is still 25.6 MHz. However, the time axis can be expanded as with a magnifier. The first and second bursts can now be seen separately.
Persistence Spectrum
This is computed from the same data as the HiRes Spectrogram Full. Shows the rate distribution over a period of 7.8 ms. The first burst with its high level can be seen clearly, whereas the second and third bursts are merged due to their having similar levels.
Magnitude
Time domain display based on the same data as the HiRes Spectrogram Full. The three bursts can be clearly seen. The display is without any time gaps. Longer recording times of up to 24 h are possible in Long-Time Scope mode.
Scope