I built this air monitor from an old TV. I took the turner and IF section and audio. I also built an EBS
alert detector. The EBS was from two 556 phase lock loop det chips. The meter on the left was a measure of the amplitude modulated IF, and was a crude measure of VIS Power. The meter on the right
was a measure of the demoded 4.5Mhz AUR. Since the aural was recovered from the vis carrier, the aural power meter would also vary. Never the less, the air monitor was crude enough to alert me when
we were OFF THE AIR. The unit was used at my house to monitor EBS alerts and also alert me when the telephone was going to ring.
This was pre 1990, and before I built my Vocalizing Radio. The Vocalizing Radio was located on site, and would anounce to me, (and most of northern california), in english, what the problem
The vocalizing radio was much more effective, sence it contained many dozens of sensors, and was a member of my Control Net.