Run this on the operator box, pick CABLE-B Output (the leg that carries remote→avd audio), and Start. It FFTs the live incoming signal and measures what the RDP playback path did to the 1200/2200 Hz AFSK tones: are they on-frequency (clock skew?), both present at full level (codec roll-off?), and continuous (packet-loss dropouts?). Then on the remote VM click Send a file — the long preamble gives the cleanest read — and watch the verdict.
| RMS level | — | peak freq | — |
| mark ≈1200 | — | space ≈2200 | — |
| measured mark | — | measured space | — |
Pick CABLE-B Output and press Start.