Frequency: 55.25 Mhz Transmitter: TV signal from Liege Bol d'air, Belgium. Receiver: Todmorden, UK. 53:42:00 N, 2:04:00 W. Path: Approx 500kM. Recording: from 16/11/00 08:00 UT to 20/11/00 13:52 UT.
The plot shows the combined mean signal strength of the two strongest TV carriers, each received in a 150Hz bandwidth and normalised by the mean level from a 100Hz wide channel centered at 2110Hz. Each sample point represents a 600 second integration. The approximate positions of Asher-McNaught dust trail predictions  are marked.
All times below are UT +/- 5 mins. Using the strength 3 level as a threshold, the 1866 peak runs from 18.275 (06:36), to 18.335 (08:02), placing the center at 18.305 (07:19). The peak signal occurs at 18.281 (06:45).
The 1866 peak of the 1650Hz carrier alone (See 1650 Hz signal strength) is better defined and runs from 18.276 (06:38), to 18.336 (08:04), center at 18.306 (07:21). The 1650Hz peak signal is at 18.330 (07:55).
Software was arranged to recognise and count meteor head echoes from the 370Hz carrier, recognised by the rapidly falling doppler shift captured in the range 500Hz to 760Hz. Head detector was muted by a noise pulse detector monitoring a 120Hz bandwidth centered on 200Hz. The above plot shows the hourly rate. The peaks appearing between 19.74 and 19.95 are caused by local interference at the receiver.
Times of the four strongest peak head counts, UT +/- 5 mins.
17.288 (17th 06:55) 17.323 (17th 07:45) 18.260 (18th 06:15) 18.309 (18th 07:25) strongest
|90 mins||17.3403 (17th 08:10)||18.3004 (18th 07:13)||Plot|
|30 mins||17.3205 (17th 07:42)||18.3056 (18th 07:20)||Plot|
|20 mins||17.3250 (17th 07:48)||18.3035 (18th 07:17)||Plot|
One final chart was done using a sigma of 8 minutes (Plot). At this resolution the two main peaks each begin to split into three sub-peaks. The times of the six peaks are
|1932:||17.2958 (07:06); 17.3285 (07:53); 17.3757 (09:01)|
|1866:||18.2928 (07:02); 18.3056 (07:20); 18.3306 (07:56)|
The signal level of the two channels combined is plotted below along with the predicted positions of the 55P/Tempel-Tuttle dust trails - based on a diagram by David Asher, Armagh Observatory;
We get a clear impression of the strong peak coinciding in both position and width with the 1866 dust trail, and this peak is preceeded by the shallower, broader peak of the 1733 trail. This latter is not really discernable as a separate peak, appearing instead as an extended introduction to the main peak. The 1932 trail from the previous morning also coincides nicely, apparently with a slightly extended tail.
Despite the plentiful supply of echoes, the location of the peaks remains open to interpretation, which demonstrates the need to combine results from several reception sites before a reliable picture of the meteor shower can be obtained. The sub-peaks apparent in some of the data are most likely to be due to the response of the signal averaging to just a few long overdense echoes, although a comparison with other radio meteor records would be interesting.
A nice writeup of the history of the Leonids and 55P/Tempel-Tuttle is available at Sky and Telescope, The Leonids: King of the Meteor Showers , by Joe Rao.