Monitored Bands

Monitored Bands
This mode allows you to monitor specific frequency bands. For example, in a cell-phone free area, the this feature can be used to monitor the frequency bands used by cell phones for the purpose of detecting prohibited transmissions.

Monitored Bands mode is similar to Monitored Frequencies mode — the main difference here is that rather than monitoring individual frequencies, the user assigns a frequency range to a single band ID.

The Monitored Bands view displays the RF signal strength that is detected at specific frequency bands defined by the user. Furthermore, the user is alerted when the RF energy detected at one of those bands exceeds a threshold (here called the Alert Threshold), again set by the user. Up to 160 bands can be specified and monitored at one time. If the signal strength of an interfering transmitter were to rise above the Alert Threshold then the corresponding bar for that band turns red (otherwise it appears green). The purpose of this feature is to alert you in the event the ambient RF energy, measured at specific bands, were to rise above a threshold value.

The bands being monitored are displayed across the horizontal axes according to their ID numbers. For example, the red bar above the number 24 in the above screen capture represents the RF energy transmitted at whatever band the user defined the 24th monitored band as. When the RF signal strength as measured at a particular band exceeds the Alert Threshold then its corresponding bar appears red, otherwise it appears green.



To specify bands you wish to monitor select Tools > Monitored Bands… from the main menu. The Monitored Bands dialog box will then appear.

The check boxes in the leftmost column allow you to select which bands you’d like to monitor — if a check appears in the check box then that band will be monitored — otherwise, if unchecked, then it will be ignored. The second column (from the left) displays the band ID displayed in the chart, as mentioned above. The third and fourth columns are used to define the Start and End frequency for that particular band ID. The last column displays a description for this band. In our example, and in the program by default, we have selected various cellular frequency bands designated by the ITU for different types of mobile telephones, as this feature is particularly useful in monitoring cell phone activity.

The Alert Threshold can be adjusted using the slider control at the bottom of the dialog box. If the signal strength at a monitored frequency exceeds the threshold, the bar above the corresponding ID number will turn red (otherwise it appears green).

As a side note, the Monitored Bands dialog box can not be accessed while the analyzer is actively scanning. That is, if the receiver is scanning and you wish to make changes to the monitored bands then it is necessary to first press the Stop scan button.