The DIFM receiver is the basic building b1ock of any wide open electronic support measure (ESM) system.
The principle used in a DIFM receiver centers around the conversion of the frequency information into an equivalent phase delay.
This article gives the details of the algorithms used to resolve the ambiguity in frequency estimates of a broadband DIFM receiver, with simultaneous good frequency accuracy capability and broad frequency coverage, along with phase error margin performance.
The generic building block of a broadband DIFM receiver is shown in Figure 1.
The following analysis assumes that only one frequency signal is present at the input of the DIFM receiver.
While practically mounting the delay lines in the DIFM receiver, there could be a marginal change in their electrical lengths due to the contouring of the delay lines.
This acceptance criterion will be especially helpful if the DIFM has to process time synchronous input signals that are likely to corrupt the phase measurements.