Fritz Wue
02-10-2005, 02:18 AM
> , but spending money on something that has a very good chance of not
> working is not something I like to do.
Yes, at least 95% chance of money lost......
> I still may find another use with my DVB receiver on L-band, like amateur
> digital television hi hi. Now to find someone who will buy the very
> expensive equipment to transmit something for me to watch!
I think a big rotary dish and going for satellite dx
is the most interesting thing you can do with your dvb rx.
In north america you are very close to europe.
(...if you have free sight to the northeastern horizon)
Here's a footprint of Intelsat 10-02 at 1degree west:
http://makeashorterlink.com/?Z5D1149A9
You may get infos here:
http://www.lyngsat.com/
> Afristar is above the horizon here
....but that can't be much. Afristar is on 21° east.
> I notice that the yagi is indeed linearly polarized. I think this is an
> inherent 3db loss when used with circularly polarized systems but the
> resultant gain of having the yagi far outweighs that loss.
right....
> I suppose the 2.3v output is to power the LNA integrated into antennas
> made specifically for worldspace?
right...
> Also, perhaps the voltage is used to select RHCP or LHCP depending on the
> transponder being listened to or used at that time.
I don't know exactly how they do it.
I always measured 2.3volt.
Maybe it's something like the 22kHz with DiSEqC.
http://www.eutelsat.org/satellites/4_5_5.html
At least all my radios have a menu where you can configure
if you are using a circular or a linear polarized antenna.
> Looking at the footprint map the beam is actually pointed my direction
> from the satellite, but they cut off everywhere on the map where the
> satellite appears below 20 degrees above the horizon (or maybe it was
> 30?). Perhaps this implies that there is still a signal in these
> directions beyond this point, but reception would be unreliable due to
> ground based obstructions.
Many infos from worldspace are unclear.
I think someone just decided to cut off everything beyond the 30 degrees
of elevation because that is about minimum for receiving the satellite
if you put the standard worldspace antenna flat on a car top. ;o)
At least they cannot have the beam attenuation outside of the lobe
as it would be possible on Ku band.
>> I will put a standard worldspace circular antenna in the focus.
>> The focus to diameter ratio of satellite dishes is usually around 0.4,
>> so a very directional receiving antenna makes no sense.
>
> This might not be such a good idea. When a circularly polarized signal
> reflects off of a dish (or flat panel or anything else) the polarity is
> reversed; LHCP becomes RHCP, and RHCP becomes LHCP. While on paper a
> reversed circular polarization signal is infinite loss, I think the real
> world figure is more along the lines of 30db.
I hope it is no problem.
My worldspace radios have no preprogrammed fixed channels,
I can do a scan across the entire band, only takes a minute or two.
So hopefully I will receive the signals with reversed polarization.
> CW while mobile is difficult but I do do it from time to time. The keyer
> is the up and down buttons on top of the microphone! Not as nice as a
> bencher iambic but it works.
Very nice! I did cw out of the car for years when I was younger.
I had a chevy caprice classic and a squeeze keyer just under the key.
The Drake TR7 fitted very well above the tunnel,
and the antenna was homemade with a big load coil at the bottom.
73, cu
Fritz -.. -.- -.... --.- ..
> working is not something I like to do.
Yes, at least 95% chance of money lost......
> I still may find another use with my DVB receiver on L-band, like amateur
> digital television hi hi. Now to find someone who will buy the very
> expensive equipment to transmit something for me to watch!
I think a big rotary dish and going for satellite dx
is the most interesting thing you can do with your dvb rx.
In north america you are very close to europe.
(...if you have free sight to the northeastern horizon)
Here's a footprint of Intelsat 10-02 at 1degree west:
http://makeashorterlink.com/?Z5D1149A9
You may get infos here:
http://www.lyngsat.com/
> Afristar is above the horizon here
....but that can't be much. Afristar is on 21° east.
> I notice that the yagi is indeed linearly polarized. I think this is an
> inherent 3db loss when used with circularly polarized systems but the
> resultant gain of having the yagi far outweighs that loss.
right....
> I suppose the 2.3v output is to power the LNA integrated into antennas
> made specifically for worldspace?
right...
> Also, perhaps the voltage is used to select RHCP or LHCP depending on the
> transponder being listened to or used at that time.
I don't know exactly how they do it.
I always measured 2.3volt.
Maybe it's something like the 22kHz with DiSEqC.
http://www.eutelsat.org/satellites/4_5_5.html
At least all my radios have a menu where you can configure
if you are using a circular or a linear polarized antenna.
> Looking at the footprint map the beam is actually pointed my direction
> from the satellite, but they cut off everywhere on the map where the
> satellite appears below 20 degrees above the horizon (or maybe it was
> 30?). Perhaps this implies that there is still a signal in these
> directions beyond this point, but reception would be unreliable due to
> ground based obstructions.
Many infos from worldspace are unclear.
I think someone just decided to cut off everything beyond the 30 degrees
of elevation because that is about minimum for receiving the satellite
if you put the standard worldspace antenna flat on a car top. ;o)
At least they cannot have the beam attenuation outside of the lobe
as it would be possible on Ku band.
>> I will put a standard worldspace circular antenna in the focus.
>> The focus to diameter ratio of satellite dishes is usually around 0.4,
>> so a very directional receiving antenna makes no sense.
>
> This might not be such a good idea. When a circularly polarized signal
> reflects off of a dish (or flat panel or anything else) the polarity is
> reversed; LHCP becomes RHCP, and RHCP becomes LHCP. While on paper a
> reversed circular polarization signal is infinite loss, I think the real
> world figure is more along the lines of 30db.
I hope it is no problem.
My worldspace radios have no preprogrammed fixed channels,
I can do a scan across the entire band, only takes a minute or two.
So hopefully I will receive the signals with reversed polarization.
> CW while mobile is difficult but I do do it from time to time. The keyer
> is the up and down buttons on top of the microphone! Not as nice as a
> bencher iambic but it works.
Very nice! I did cw out of the car for years when I was younger.
I had a chevy caprice classic and a squeeze keyer just under the key.
The Drake TR7 fitted very well above the tunnel,
and the antenna was homemade with a big load coil at the bottom.
73, cu
Fritz -.. -.- -.... --.- ..