Resolution Bandwidth (RBW)
The following images represent various signal level examples of the RF spectrum from 30 MHz to 300 MHz.
These signals were captured and analyzed during runtime sessions to demonstrate the importance of selecting the optimal Resolution bandwidth (RBW) from a TSCM perspective.
It is not always necessary to utilize extremely narrow resolution bandwidth settings to achieve and acceptable level of discrimination at the signal display level.
However, it is essential that the technical operator consider the RBW settings based on the threat level and threat technology anticipated.
Resolution Bandwidth (RBW) can affect the noise floor level and must be taken into consideration during deployment.
This information is extracted from the Kestrel TSCM ® Professional Software | Certified Technical Operator (CTO) TM training program.
30 MHz to 300 MHz (5 MHz RBW)
At 5 MHz RBW only large Intermediate Frequency (IF) filter blocks are rendered and multiple narrow band signal events can go unobserved. The ambient noise floor is also higher making it impossible to discern narrow bandwidth signal events. This prevents the detection and identification of low-level potentially hostile signals of interest.
30 MHz to 300 MHz (2.5 MHz RBW)
At 2.5 MHz RBW we can see the presence of additional signal events within the IF filter block that were not visible at 5 MHz RBW.
30 MHz to 300 MHz (1.3 MHz RBW)
At 1.3 MHz RBW we can now see the clear presence of these additional signal events within the IF filter block more definitively.
30 MHz to 300 MHz (631 kHz RBW)
Narrowing the RBW to 631 kHz even more discrete signal events can be observed and we are now seeing a the nature of the actual bandwidth of the display signal events. The ambient noise floor continues to become lower exposing additional low-level signal event that were below the noise floor when utilizing wider IF bandwidth filters.
30 MHz to 300 MHz (316 kHz RBW)
At 316 kHz RBW additional low energy signal events begin to appear more clearly at or just above the ambient noise floor level.
30 MHz to 300 MHz (157 kHz RBW)
At 157 kHz RBW we see even more evidence of low level signal activity as the RBW is narrowed and the noise floor continues to drop.
30 MHz to 300 MHz (79 kHz RBW)
At 79 kHz RBW signals near the ambient noise floor now can be discerned as potential signals of interest.
30 MHz to 300 MHz (40 kHz RBW)
Narrowing the RBW to 40 kHz we can now see that multiple signals of interest are presented and would benefit by a zoom factor to complete a more detailed analysis.
30 MHz to 300 MHz (20 kHz RBW)
At 20 kHz signal event activity is clearly defined and it is unlikely that the technical operator would miss mission critical spectrum data events during runtime or post analysis.
30 MHz to 300 MHz (9.9 kHz RBW)
At 9.9 kHz RBW the ambient noise floor continues to lower and signals that could not be observed at wider resolution bandwidth settings are now clearly observable.
30 MHz to 300 MHz (4.9 kHz RBW)
Narrowing the resolution bandwidth to 4.9 kHz we see the ambient noise floor has continued to lower and even more narrow band signal events become observable across the spectrum.
Wide Resolution Bandwidth Selection
| 5 MHz | 2.5 MHz | 1.3 MHz | 631 kHz | 316 kHz | 157 kHz |
Wider RBW settings result in a higher ambient noise floor.
Wider RBW setting make it impossible to see low level signals that are close to the ambient noise floor.
Wider RBW settings result in the inability to discern narrow bandwidth signal events within a wide IF filter.
Wide RBW settings result in an apparent increase in sweep speed.
Narrow Resolution Bandwidth Selection
| 79 kHz | 40 kHz | 20 kHz | 9.9 kHz | 4.9 kHz |
Narrow RBW settings result in lower ambient noise floor.
Narrow RBW settings make it possible to see low level signals that are close to the ambient noise floor.
Narrow RBW settings result in the ability to discern narrow bandwidth signal events within a narrow IF filter.
Narrow RBW settings result in an apparent slower sweep speed.