MMA Memo #170

System Temperatures, Single Versus Double Sideband Operation, and Optimum Receiver Performance

P. R. Jewell [1], J. G. Mangum [2]

April 29, 1997

Keywords: receiver, antenna, single sideband, double sideband

This paper discusses the relative observing efficiency of single sideband (SSB) and double sideband (DSB) receiver systems in the presence of atmospheric and antenna losses. We use the antenna parameters currently specified for the MMA antennas and atmospheric opacities appropriate to an excellent site such as the Chilean or Mauna Kea sites under consideration for the MMA. We find that for spectroscopic observations in one sideband, SSB measurements are always more efficient. Below 400 GHz, the observing time advantage is 50-80%. Above 400 GHz, the advantage is over a factor of 2, indicating that SSB-mode observing is more efficient even if spectral lines of interest are present in both sidebands. We discuss the goals for the ultimate, practical receiver performance that we should aim for in the presence of atmospheric and telescope losses. Observing efficiencies are displayed as a function of frequency using atmospheric opacity models as input. We also develop some analytic expressions for SSB and DSB observing.

[1] JACH
[2] NRAO

From here, you can:

View an HTML version of MMA Memo #170.

Download a 0.3MB gzipped postscript version of MMA Memo #170 from

here

Last modified: 09 December, 1999