Anyone interested in science and outer space exploration knows that
today Huygens probe had just now successfully landed on Titan,
Saturn's largest moon. The probe began transmitting radio beacon
siginal at 11:25 CET, and the Green Bank radio telescope in West
Virginia, USA, picked up this faint but unmistakable radio signal (2040
MHz) from the probe.

My wondering is, considering the huge distance between Titan(Saturn)
and Earth, and the undirectionality of the beacon radio signal (not the
ones modulated with scientifically data that will be picked up by
Cassini and relays directionally to Earth), the telescope in WV must be
very very sensitive. Can anyone estimate what sensitivity it has, and
compare it with a regular radio receiver (say, 0.1uV)?

They used a network of radio telescopes all over the planet to collect enough energy.

http://antwrp.gsfc.nasa.gov/apod/astropix.html

http://spaceweather.com/

Peace +

"C Bun" wrote in message oups.com...
Anyone interested in science and outer space exploration knows that
today Huygens probe had just now successfully landed on Titan,
Saturn's largest moon. The probe began transmitting radio beacon
siginal at 11:25 CET, and the Green Bank radio telescope in West
Virginia, USA, picked up this faint but unmistakable radio signal (2040
MHz) from the probe.

My wondering is, considering the huge distance between Titan(Saturn)
and Earth, and the undirectionality of the beacon radio signal (not the
ones modulated with scientifically data that will be picked up by
Cassini and relays directionally to Earth), the telescope in WV must be
very very sensitive. Can anyone estimate what sensitivity it has, and
compare it with a regular radio receiver (say, 0.1uV)?

On 14 Jan 2005 12:25:54 -0800, "C Bun" wrote:

Anyone interested in science and outer space exploration knows that
today Huygens probe had just now successfully landed on Titan,
Saturn's largest moon. The probe began transmitting radio beacon
siginal at 11:25 CET, and the Green Bank radio telescope in West
Virginia, USA, picked up this faint but unmistakable radio signal (2040
MHz) from the probe.

My wondering is, considering the huge distance between Titan(Saturn)
and Earth, and the undirectionality of the beacon radio signal (not the
ones modulated with scientifically data that will be picked up by
Cassini and relays directionally to Earth), the telescope in WV must be
very very sensitive. Can anyone estimate what sensitivity it has, and
compare it with a regular radio receiver (say, 0.1uV)?
The key isn't as much sensitivity of the receiver. That is seriously
limited by background noise anyway to something around .5 microvolts
unless you use synchronous detection. The game at Green Bank and the
others is the huge gain over an isotropic radiator the big dish gives.

If an 8 ft dish gives about 40 db, an 80 ft dish is about 60db, 800
foot dish (like Aericibo) 80 db gain over an isostropic radiator.
When you have 60db in the antenna system, ta picowatt becomes a
microwatt, and a microwatt turns into a watt.

There's a nearby ski area, Snowshoe, that has to work closely with the
NRAO to keep from interfering with the deep space transmissions.

_Wired_ had a good article last year about the problems NRAO faces.

http://www.wired.com/wired/archive/12.02/quiet_pr.html


Issue 12.02 - February 2004

The Quiet Zone
Cell phones, pagers, Wi-Fi, Bluetooth - the wireless revolution is
everywhere. Except here.

By John Geirland

.....
The subjects of radio astronomy are astronomically large, but the
signals they produce are astronomically weak by the time they reach
Earth. These emissions are measured in Janskys, named for the father of
radio astronomy, Karl Jansky. A Jansky is based on
0.00000000000000000000000001 watts - and that's a big signal at Green
Bank. Even a musical greeting card playing at the base of the telescope
could produce anomalous spikes in the data of an unlucky astronomer
trying to study stellar gases. If the interference is strong enough,
the telescope's ultrasensitive first amplifier - cooled by liquid
helium to minimize internal noise - shuts down.


There was an article in the _WSJ_ two months ago as well.

http://www.mindfully.org/Technology/...ing15nov04.htm


Be Quiet. We're Listening.
Scientists in West Virginia are trying to hear what the universe has to
say.
But wireless devices are making it increasingly difficult.
MARCELO PRINCE / Wall Street Journal 15nov04

.....
The task of preserving the Quiet Zone largely falls to Mr. Reynolds and
a team of scientists at Green Bank. The radio frequency interference
team spends hours every week driving around in a vehicle equipped with
sensitive antennas and special gear to pinpoint local sources of
interference, like a broken knot in an electric fence. They must also
monitor thousands of cellphone towers and broadcast antennas in the
zone to ensure they don't disrupt the telescope -- an increasingly
time-consuming and difficult task.

I just now read this article at, www.bignewsnetwork.com Infant stars
still forming discovered in Milkyway.
cuhulin

matt weber wrote:

The key isn't as much sensitivity of the receiver. That is seriously
limited by background noise anyway to something around .5 microvolts
unless you use synchronous detection. The game at Green Bank and the
others is the huge gain over an isotropic radiator the big dish gives.

If an 8 ft dish gives about 40 db, an 80 ft dish is about 60db, 800
foot dish (like Aericibo) 80 db gain over an isostropic radiator.
When you have 60db in the antenna system, ta picowatt becomes a
microwatt, and a microwatt turns into a watt.

Add to that a cryogenically cooled (liquid nitrogen) front-end (RF amp)
to greatly reduce the thermal noise from the componants in that circuit.


----== Posted via Newsfeeds.Com - Unlimited-Uncensored-Secure Usenet News==----
http://www.newsfeeds.com The #1 Newsgroup Service in the World! 100,000 Newsgroups
---= East/West-Coast Server Farms - Total Privacy via Encryption =---

Just trying to read the old messages after the huge effort to purge the many
messages that are not relevant.

The article referenced below is still available - wonder-of-wonders. I
worked at Green Bank in the late 50s and it was very radio quiet. To make
sure that I did not cause a problem, I would drive over the next ridge to
operate my amateur radio station that I keep on the back seat of my 7
cylinder Chrysler. Eventually, it was found that I could operate on the
site without causing a problem. I ran a dipole between two trees that were
next to Reber's old antenna (used to make the first radio map of the sky).
He was a very interesting fellow. Sensitivities were not as good then as
they are now.

Sure a good place to listen and to see. The article is worth a read.
73 Mac
--
J. Mc Laughlin; Michigan U.S.A.
Home:
wrote in message
oups.com...
There's a nearby ski area, Snowshoe, that has to work closely with the
NRAO to keep from interfering with the deep space transmissions.

_Wired_ had a good article last year about the problems NRAO faces.

http://www.wired.com/wired/archive/12.02/quiet_pr.html


Issue 12.02 - February 2004

The Quiet Zone
Cell phones, pagers, Wi-Fi, Bluetooth - the wireless revolution is
everywhere. Except here.

By John Geirland

....
The subjects of radio astronomy are astronomically large, but the
signals they produce are astronomically weak by the time they reach
Earth. These emissions are measured in Janskys, named for the father of
radio astronomy, Karl Jansky. A Jansky is based on
0.00000000000000000000000001 watts - and that's a big signal at Green
Bank. Even a musical greeting card playing at the base of the telescope
could produce anomalous spikes in the data of an unlucky astronomer
trying to study stellar gases. If the interference is strong enough,
the telescope's ultrasensitive first amplifier - cooled by liquid
helium to minimize internal noise - shuts down.


There was an article in the _WSJ_ two months ago as well.


http://www.mindfully.org/Technology/...reasing15nov04.
htm


Be Quiet. We're Listening.
Scientists in West Virginia are trying to hear what the universe has to
say.
But wireless devices are making it increasingly difficult.
MARCELO PRINCE / Wall Street Journal 15nov04

....
The task of preserving the Quiet Zone largely falls to Mr. Reynolds and
a team of scientists at Green Bank. The radio frequency interference
team spends hours every week driving around in a vehicle equipped with
sensitive antennas and special gear to pinpoint local sources of
interference, like a broken knot in an electric fence. They must also
monitor thousands of cellphone towers and broadcast antennas in the
zone to ensure they don't disrupt the telescope -- an increasingly
time-consuming and difficult task.