I only scanned the replies so far, so may have missed a similar
reference, but recent editions of "Reference Data for Engineers" (used
to be ITT Reference Data for Radio Engineers) in the "noise" chapter
have a couple "Radio-sky maps," one for 136MHz and one for 400MHz.
There's a great deal of variation, depending on where you point your
antenna (assuming a very narrow beamwidth). On 400MHz, at about 18
hours RA and -30 degrees declination, you'll get about 280 kelvins; at
10 hours and +30 degrees, you'll get about 15 kelvins. On 136MHz in
the same two directions, it's about 3600 and 200 kelvins. Perhaps such
sky maps are available online somewhere for a wider range of
frequencies.

Cheers,
Tom

Owen Duffy wrote:
Googling about turns up a little, and only a little information on the
expected sky noise temperature on 2m, 70cm, 23cm.

The information isn't very consistent. For example, articles that talk
about the sky noise below 200MHz being 100K or more, and amateur
articles talking about sky noise at 144MHz being "hundreds of
degrees".

Similary, for 70cm a broad brush figure of 45K seems to be used, and
others talk about 20K away from the galactic plane and 60K on the
galactic plane. (Yes, they will be blurred together with a low gain
antenna.)

Some discussions treat the "sky noise temperature" as if it includes
spillover noise (eg in cold sky / hot earth measurements).

Can anyone recommend a reliable source of sky noise characteristics
for these bands.

Additionally, I am interested in the range of ambient noise levels
experienced for these bands for traditional DX activity (ie antennas
at zero elevation.

Alternatively, are satellite beacons a reliable source for measuring
station receive performance?

Or... is there some other better way of measuring station receive
performance?

Owen
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