Latest Mars Relay Power Spectra

We are attempting to provide "near" real-time display of power spectra of the Mars Relay UHF signal as received at the SRI/Stanford 150-foot dish. Bandwidth limitations prevent us from displaying all of our spectra on this site. We do plan, however, to display new spectra every two or three minutes while we are receiving the Mars Relay signal. We will deliver new spectra as fast as our systems can reasonably manage without compromising our ability to track the Mars Relay signal through the spacecraft spin cycle and the many transmission modes.

The most recent available spectra are shown below. A time tag appears in the title of each plot. The center frequency of the spectrum is also indicated. The frequency axis units are kiloHertz and the magnitude units are dB. The image was posted on this Web server at:

Mon Nov 25 15:58:02 UTC 1996

Note that the strong signals near DC are NOT the MR beacon. The receiver is currently tuned so that the beacon should appear around 4.5 kHz. The latest processing parameters are:

437.1078 MHz, 15.0 kHz, 2048, 6

where the first value is the center frequency of our system, the second value is our sampling rate, the third value is the length of the Discrete Fourier Transform which we are using for estimation of the power spectrum of the Relay signal, and the fourth value is the number of Transforms which we are accumulating per spectrum to further improve our SNR.

If you are running Netscape 1.1 or later, the latest spectra should update automatically every two or three minutes. If that does not seem to happen or if you are running a browser which does not support the (admittedly non-standard) Refresh HTML tag, then "Reload" the page every few minutes to see the latest and greatest. If we are not acquiring new data, the image will not update (although it will still refresh). Sorry about that!!!

You may also view the latest photograph from the control room at the SRI/Stanford 150-foot antenna.

Last updated: 26 November 1996
Joe Twicken