Remote Spectrum Monitoring & time difference of arrival (TDOA). ANRITSU.

TDOA support for MS27201A and MS2090A

MX280001A Vision now supports both the MS2090A (PORTABLE HANDHELD SPECTRUM ANALYZER) and MS27201A (REMOTE SPECTRUM MONITOR PROBE) Option 401 Vision Locate enabled.

The option uses a time difference of arrival (TDOA), which is a powerful tool for locating a static and moving object. Each node of the triangle uses its GPS to identify its location. All three nodes listen for the modulated RF signal, save the IQ data, and time stamp it. Based on the time each node receives the modulated RF signal, a parabola is drawn from each node. This enables Vision to triangulate the location of the object.

Using higher frequencies has become common as the RF spectrum becomes more crowded. Vision's TDOA works up to 54 GHz (MS2090A and MS27201A). We are enabling coverage of the entire FR2 band. Customers can confidently buy their system, knowing it will keep up with the ever-increasing frequency bands.

A higher frequency means that the size of the triangle must be smaller due to the higher frequency having significant loss. An MS2090A can now be a node in the triangle, enabling customers to adjust the triangle for optimal triangulation.

Using the same MS2090A, customers can now use MIH to reduce the search area and carry the unit on foot for the last leg of locating the RF transmitter. The MS2090A would have to have a backhaul connection connecting it to Vision MX280001A.

 A combination of MS2090A and MS27201A is set up to do TDOA.

All three units are connected via backhaul.

Selecting the desired three RSM for POA

Customers with more than three nodes can select the trace they want for POA. All the nodes will show up on the screen, allowing the user to select the nodes for POA. By default, the three closest to the source will be selected.

The RF spectrum is full of activity in the modern theater of operations, making locating a transmitter complex.

Not only can hostile RF sources interfere with operations, but so can friendly equipment that has not been installed correctly. Although using a direction-finding antenna provides mobility, it can only offer a single vector and still lacks the information needed to triangulate the source.

The directional antenna must relocate to obtain a second vector; this can be problematic if the RF source is mobile and not consistently transmitting.

Identifying the location of an RF source starts at the macro scale. Time difference of arrival (TDOA) is a technique for geo-locating RF sources using three more spectrum analyzers (SPAs). TDOA can provide an accurate (< 100 m) estimate of the transmitter in a short period. A modulated signal is transmitted from an unknown source and captured by three or more SPAs. Each measurement captured by the SPA is going to be shifted in time as each signal arrives at the SPA at a different time. The shift between each of the SPAs is plotted as a set of hyperbolic lines. The line’s intersection indicates the source’s location. Anritsu’s remote spectrum monitor (RSM) MS27201A covers up to 54 GHz with TDOA and makes for a powerful static tool.

Although TDOA is very effective, it is traditionally a static setup. However, the handheld Field Master Pro™ MS2090A Spectrum Analyzer also has TDOA, no longer limiting TDOA to a fixed setup. Any handheld Field Master Pro can be part of the triangle in TDOA. The area of triangulation can expand, shrink, and adjust to meet these needs. As we increase the frequency in the spectrum, the distance between transmitters becomes shorter. Using the field Master Pro, the triangle can change to capture the higher frequency signals. As a portable handheld unit, it can be carried for spectrum clearing and set up as an RSM.

During spectrum clearing, an RF transmitter can easily be identified with the feature real-time spectrum analyzer (RTSA) on the Field Master Pro MS2090A and Remote Spectrum Monitor MS27201A. RTSA allows the detection of even pulse signals. Connecting the handheld to a backhaul turns the unit into a mobile RSM. The GPS provides the location of the handheld SPA. The GPS also allows synchronization of multiple RSMs and Field Master Pros for TDOA. The RF signal is captured via IQ, timestamped, and streamed back through the user’s backhaul.

Since the IQ is time-stamped, a slower backhaul will not affect the accuracy of TDOA.

Using the same handheld SPA to look for an RF source at a macro scale is also used to drill down its final location. It can now perform mobile interference hunting (MIH) with Anritsu’s Mobile InterferenceHunter MX280007A software by connecting the Field Master Pro to a computer with InterferenceHunter and an appropriate antenna. The MIH software will triangulate the transmitter’s location as the SPA is driven near the RF source. It does this by comparing the signal strength and location of the unit using Anritsu’s unique algorithm to estimate the transmitter’s location.