We are often told that our earliest TV and radio signals are out there in space travelling at the speed of light. But doesn't the power go down by the inverse square law? Also what about additive noise? Surely if anybody 60 light years away was to listen they would hear only noise? W.King
OT: TV and radio signals in Space
Started by ●June 18, 2007
Reply by ●June 18, 20072007-06-18
gyansorova@gmail.com writes:> We are often told that our earliest TV and radio signals are out there > in space travelling at the speed of light. But doesn't the power go > down by the inverse square law? Also what about additive noise? Surely > if anybody 60 light years away was to listen they would hear only > noise? > > W.KingHi W.King, Yes, the power goes down by the inverse square law. However, power alone doesn't dictate receivability. What also matters is the bandwidth and the noise temperature of the receiver, which can be made arbitrarily small. Notice also that there is no "additive noise" in space except for blackbody radiation, and that depends on where your receive antenna is looking. Otherwise the noise is set by the noise temperature of the receiver's front-end. -- % Randy Yates % "Bird, on the wing, %% Fuquay-Varina, NC % goes floating by %%% 919-577-9882 % but there's a teardrop in his eye..." %%%% <yates@ieee.org> % 'One Summer Dream', *Face The Music*, ELO http://home.earthlink.net/~yatescr
Reply by ●June 18, 20072007-06-18
gyansorova@gmail.com writes:> We are often told that our earliest TV and radio signals are out there > in space travelling at the speed of light. But doesn't the power go > down by the inverse square law? Also what about additive noise? Surely > if anybody 60 light years away was to listen they would hear only > noise? > > W.KingHi W.King, Yes, the power goes down by the inverse square law. However, power alone doesn't dictate receivability. What also matters is the bandwidth and the noise temperature of the receiver, which can be made arbitrarily small. Notice also that there is no "additive noise" in space except for blackbody radiation, and that depends on where your receive antenna is looking. Otherwise the noise is set by the noise temperature of the receiver's front-end. -- % Randy Yates % "Bird, on the wing, %% Fuquay-Varina, NC % goes floating by %%% 919-577-9882 % but there's a teardrop in his eye..." %%%% <yates@ieee.org> % 'One Summer Dream', *Face The Music*, ELO http://home.earthlink.net/~yatescr
Reply by ●June 18, 20072007-06-18
gyansorova@gmail.com writes:> We are often told that our earliest TV and radio signals are out there > in space travelling at the speed of light. But doesn't the power go > down by the inverse square law? Also what about additive noise? Surely > if anybody 60 light years away was to listen they would hear only > noise? > > W.KingHi W.King, Yes, the power goes down by the inverse square law. However, power alone doesn't dictate receivability. What also matters is the bandwidth and the noise temperature of the receiver, which can be made arbitrarily small. Notice also that there is no "additive noise" in space except for blackbody radiation, and that depends on where your receive antenna is looking. Otherwise the noise is set by the noise temperature of the receiver's front-end. -- % Randy Yates % "Bird, on the wing, %% Fuquay-Varina, NC % goes floating by %%% 919-577-9882 % but there's a teardrop in his eye..." %%%% <yates@ieee.org> % 'One Summer Dream', *Face The Music*, ELO http://home.earthlink.net/~yatescr
Reply by ●June 18, 20072007-06-18
gyansorova@gmail.com writes:> We are often told that our earliest TV and radio signals are out there > in space travelling at the speed of light. But doesn't the power go > down by the inverse square law? Also what about additive noise? Surely > if anybody 60 light years away was to listen they would hear only > noise? > > W.KingHi W.King, Yes, the power goes down by the inverse square law. However, power alone doesn't dictate receivability. What also matters is the bandwidth and the noise temperature of the receiver, which can be made arbitrarily small. Notice also that there is no "additive noise" in space except for blackbody radiation, and that depends on where your receive antenna is looking. Otherwise the noise is set by the noise temperature of the receiver's front-end. -- % Randy Yates % "Bird, on the wing, %% Fuquay-Varina, NC % goes floating by %%% 919-577-9882 % but there's a teardrop in his eye..." %%%% <yates@ieee.org> % 'One Summer Dream', *Face The Music*, ELO http://home.earthlink.net/~yatescr
Reply by ●June 18, 20072007-06-18
gyansorova@gmail.com writes:> We are often told that our earliest TV and radio signals are out there > in space travelling at the speed of light. But doesn't the power go > down by the inverse square law? Also what about additive noise? Surely > if anybody 60 light years away was to listen they would hear only > noise? > > W.KingHi W.King, Yes, the power goes down by the inverse square law. However, power alone doesn't dictate receivability. What also matters is the bandwidth and the noise temperature of the receiver, which can be made arbitrarily small. Notice also that there is no "additive noise" in space except for blackbody radiation, and that depends on where your receive antenna is looking. Otherwise the noise is set by the noise temperature of the receiver's front-end. -- % Randy Yates % "Bird, on the wing, %% Fuquay-Varina, NC % goes floating by %%% 919-577-9882 % but there's a teardrop in his eye..." %%%% <yates@ieee.org> % 'One Summer Dream', *Face The Music*, ELO http://home.earthlink.net/~yatescr
Reply by ●June 18, 20072007-06-18
On Jun 19, 12:26 pm, Randy Yates <y...@ieee.org> wrote:> gyansor...@gmail.com writes: > > We are often told that our earliest TV and radio signals are out there > > in space travelling at the speed of light. But doesn't the power go > > down by the inverse square law? Also what about additive noise? Surely > > if anybody 60 light years away was to listen they would hear only > > noise? > > > W.King > > Hi W.King, > > Yes, the power goes down by the inverse square law. However, power alone > doesn't dictate receivability. What also matters is the bandwidth and > the noise temperature of the receiver, which can be made arbitrarily > small. > > Notice also that there is no "additive noise" in space except for > blackbody radiation, and that depends on where your receive antenna > is looking. Otherwise the noise is set by the noise temperature of > the receiver's front-end. > -- > % Randy Yates % "Bird, on the wing, > %% Fuquay-Varina, NC % goes floating by > %%% 919-577-9882 % but there's a teardrop in his eye..." > %%%% <y...@ieee.org> % 'One Summer Dream', *Face The Music*, ELOhttp://home.earthlink.net/~yatescrSo has anybody done the Maths - say 60 light years at the power output from a typical National Radio station of the time. Would have been AM with a bandwidth say 5kHz.
Reply by ●June 18, 20072007-06-18
gyansorova@gmail.com writes:> On Jun 19, 12:26 pm, Randy Yates <y...@ieee.org> wrote: >> gyansor...@gmail.com writes: >> > We are often told that our earliest TV and radio signals are out there >> > in space travelling at the speed of light. But doesn't the power go >> > down by the inverse square law? Also what about additive noise? Surely >> > if anybody 60 light years away was to listen they would hear only >> > noise? >> >> > W.King >> >> Hi W.King, >> >> Yes, the power goes down by the inverse square law. However, power alone >> doesn't dictate receivability. What also matters is the bandwidth and >> the noise temperature of the receiver, which can be made arbitrarily >> small. >> >> Notice also that there is no "additive noise" in space except for >> blackbody radiation, and that depends on where your receive antenna >> is looking. Otherwise the noise is set by the noise temperature of >> the receiver's front-end. >> -- >> % Randy Yates % "Bird, on the wing, >> %% Fuquay-Varina, NC % goes floating by >> %%% 919-577-9882 % but there's a teardrop in his eye..." >> %%%% <y...@ieee.org> % 'One Summer Dream', *Face The Music*, ELOhttp://home.earthlink.net/~yatescr > > > So has anybody done the Maths - say 60 light years at the power output > from a typical National Radio station of the time. Would have been AM > with a bandwidth say 5kHz.http://www.satsig.net/seticalc.htm -- % Randy Yates % "Bird, on the wing, %% Fuquay-Varina, NC % goes floating by %%% 919-577-9882 % but there's a teardrop in his eye..." %%%% <yates@ieee.org> % 'One Summer Dream', *Face The Music*, ELO http://home.earthlink.net/~yatescr
Reply by ●June 18, 20072007-06-18
gyansorova@gmail.com writes:> On Jun 19, 12:26 pm, Randy Yates <y...@ieee.org> wrote: >> gyansor...@gmail.com writes: >> > We are often told that our earliest TV and radio signals are out there >> > in space travelling at the speed of light. But doesn't the power go >> > down by the inverse square law? Also what about additive noise? Surely >> > if anybody 60 light years away was to listen they would hear only >> > noise? >> >> > W.King >> >> Hi W.King, >> >> Yes, the power goes down by the inverse square law. However, power alone >> doesn't dictate receivability. What also matters is the bandwidth and >> the noise temperature of the receiver, which can be made arbitrarily >> small. >> >> Notice also that there is no "additive noise" in space except for >> blackbody radiation, and that depends on where your receive antenna >> is looking. Otherwise the noise is set by the noise temperature of >> the receiver's front-end. >> -- >> % Randy Yates % "Bird, on the wing, >> %% Fuquay-Varina, NC % goes floating by >> %%% 919-577-9882 % but there's a teardrop in his eye..." >> %%%% <y...@ieee.org> % 'One Summer Dream', *Face The Music*, ELOhttp://home.earthlink.net/~yatescr > > > So has anybody done the Maths - say 60 light years at the power output > from a typical National Radio station of the time. Would have been AM > with a bandwidth say 5kHz.http://www.satsig.net/seticalc.htm -- % Randy Yates % "Bird, on the wing, %% Fuquay-Varina, NC % goes floating by %%% 919-577-9882 % but there's a teardrop in his eye..." %%%% <yates@ieee.org> % 'One Summer Dream', *Face The Music*, ELO http://home.earthlink.net/~yatescr
Reply by ●June 18, 20072007-06-18
gyansorova@gmail.com writes:> On Jun 19, 12:26 pm, Randy Yates <y...@ieee.org> wrote: >> gyansor...@gmail.com writes: >> > We are often told that our earliest TV and radio signals are out there >> > in space travelling at the speed of light. But doesn't the power go >> > down by the inverse square law? Also what about additive noise? Surely >> > if anybody 60 light years away was to listen they would hear only >> > noise? >> >> > W.King >> >> Hi W.King, >> >> Yes, the power goes down by the inverse square law. However, power alone >> doesn't dictate receivability. What also matters is the bandwidth and >> the noise temperature of the receiver, which can be made arbitrarily >> small. >> >> Notice also that there is no "additive noise" in space except for >> blackbody radiation, and that depends on where your receive antenna >> is looking. Otherwise the noise is set by the noise temperature of >> the receiver's front-end. >> -- >> % Randy Yates % "Bird, on the wing, >> %% Fuquay-Varina, NC % goes floating by >> %%% 919-577-9882 % but there's a teardrop in his eye..." >> %%%% <y...@ieee.org> % 'One Summer Dream', *Face The Music*, ELOhttp://home.earthlink.net/~yatescr > > > So has anybody done the Maths - say 60 light years at the power output > from a typical National Radio station of the time. Would have been AM > with a bandwidth say 5kHz.http://www.satsig.net/seticalc.htm -- % Randy Yates % "Bird, on the wing, %% Fuquay-Varina, NC % goes floating by %%% 919-577-9882 % but there's a teardrop in his eye..." %%%% <yates@ieee.org> % 'One Summer Dream', *Face The Music*, ELO http://home.earthlink.net/~yatescr
