The spectrogram on this page is not continuously active. When active, it automatically reloads every 4 minutes but the plots themselves are uploaded at an interval determined by the time scale, typically 12 minutes.

Narrowband Spectrum Monitor: One or two Icom R-75 or R-8600 general coverage receivers on a rotable HF log periodic antenna. The receivers are set to LSB and tuned to nominal 1 000 kHz above the carrier frequency. The HF log periodic dipole array antenna is pointed 107° or 195° True azimuths toward WWV or WWVH.

The chart shows the relative frequency of one or two signals over time; usually the higher carrier frequency is above chart center. Frequencies monitored usually are WWV and WWVH time services on 5, 10, 15, 20 and 25 MHz (the latter is WWV only) but other frequencies may be used (see below). The vertical scale is in Hz and shows the approximate offset of the received signal from the transmitted carrier frequency. The signal level is under control of the software automatic gain control.

As of 02 April 2021, the trace nearest 995 Hz, if present, is the United States time-frequency stations WWV or WWVH on 15 MHz, the trace nearest 1005 Hz, if present, is WWV or WWVH on 20 MHz and the trace nearest 1015 Hz, if present, is WWV on 25 MHz.

Meteor Monitor commissioned 7 June, 2014