Mobile InterferenceHunter Help : Using the MIH : Finding the Interferer
Finding the Interferer
Mobile InterferenceHunter is not designed to provide directions to the precise location of an interferer source. Its goal is to get you close enough that you can get out of the car in close proximity and do the last stage of the hunt on foot. The longer you spend in the car, the closer you can get with Mobile InterferenceHunter, but at some point you will have to get out and do the last steps on foot. In practice and with a little experience, Mobile InterferenceHunter will get you very close to the exact building or source. In the final stage of the driving portion of the hunt, watch the power bars and try to park your car as close to the maximum bar readout as possible. The RF source will be very near.
Preparing for the Drive
Below is a quick rundown of the steps needed to get set up for a hunt.
1. Place the mag-mount antenna on top of the vehicle.
2. Connect it to an Anritsu spectrum analyzer.
3. Turn on the instrument.
4. Set the instrument measurement to Channel Power (review your instrument user documentation for details on setting up this measurement mode for your model).
5. Locate the interferer signal on the instrument.
6. Connect the computer and Anritsu Spectrum Analyzer via Ethernet or Wi-Fi.
7. Run the MIH program.
8. Set up the MIH software for interference hunting, starting with Scan Driving mode to isolate the general interferer signal.
9. Switch to Spot mode to pinpoint its location.
Driving Around
Before driving to locate an interfering signal source, acquaint yourself thoroughly with the MIH display and Toolbar. This will minimize the amount of glances at the screen you will need to make while driving around. Using the Voice Prompts and/or Audio Tones also helps in minimizing glances at the display.
Start MIH in Scan Drive mode at a location where you know an interference problem occurs, such as a base station that is having interference problems. If you can obtain the interferer signal from your starting location, drive in the direction of the signal. In the Power vs. Time display, observe the increase or decrease in signal level. If the signal level decreases over time, most likely you are driving away from the signal source. If the signal level increases over time, you are probably heading in the direction of the signal source.
Use the breadcrumb color and size to indicate the relative location of the emitter as well as the heat map color shading. A large yellow breadcrumb generally means higher signal power suggesting you are closer to the source. A small dark breadcrumb means low signal power and that you are probably far from or driving away from the signal source. Darker shaded areas of the heat map indicate stronger signals.
The example below is from Scan Drive mode showing that you are driving toward the signal. Note that MIH will only scan out to the Search Boundary, the size of which is set via Settings | Search Grid Width.
Approaching the Interferer
The example below is showing that you have driven past the signal and have isolated a general area of where the interferer could be, shown by the darker shaded region. The next step is to circle around the shaded area to continue narrowing it down into a smaller circle before switching to Spot mode.
Isolating the Interferer
Once you have isolated the general area, you can switch to Spot mode to further isolate the signal and start collecting signal data.
Pinpointing the Interferer
As more data is collected, a green arrow will show on the map pointing you in the general direction of the signal source. A shadow circle replaces the arrow and will appear on the map as additional data is accumulated. The shadow circle is the general area where the signal is coming from. Its initial size may be large but will decrease in size as you get closer to the signal source and the power level of the interferer increases.
At times you may want to park and evaluate the data received. Once a very close approximation on location has been established, get out of the vehicle and proceed on foot with a handheld instrument and directional antenna to find the exact emitter location.