What do values expressed in dBmV that are preceded by a minus sign represent?

Values expressed in dBmV (decibels relative to 1 millivolt) that are preceded by a minus sign indicate levels that are below the reference point of 1 millivolt. Specifically, dBmV is a logarithmic representation of voltage levels relative to 1 millivolt; thus, when you see a negative value, it signifies that the actual voltage is less than 1 millivolt. For instance, a value of -10 dBmV corresponds to a voltage that is a fraction of 1 millivolt, specifically about 0.316 millivolts. This negative dBmV indicates a drop in signal strength, which is common in electronic and communication systems, where maintaining a certain signal level is crucial for performance. Understanding this concept is essential for interpreting measurements in related fields, including telecommunications and broadcasting.