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Re: Arabic (?) music on FO-20 !!!



Hi Scott,

Reply to 1.
-----------
The FO-20 transponder frequencies are as follows:
Uplink: 145.900 - 146.000 MHz
Downlink: 435.795 - 435.900 MHz (inverted)

It is inverted what means that 145.900MHz is equal to 435.900MHz.
When going up 50kHz in uplink frequency to 145.950MHz you get 50kHz down in 
downlink frequency what is 435.850MHz etc...
This is also the centre freq. where is most activity...

Reply to 2.
-----------
FM on a inverting transponder sounds like normal FM.
The transponder inverts the FM spectrum but when you know how a FM spectrum 
looks like, you find out that the inverted FM signal is equal to the 
none-inverting FM signal.

I need a picture to explain it more in detail, but unfortunatly 
email/amsat-bb has no graphic possibility :-(

Maybe someone else can explain it better in words...

73 de PE1RAH, William
---

>From: Scott Townley <nx7u@cox.net>
>Reply-To: nx7u@arrl.net
>To: "William Leijenaar" <pe1rah@hotmail.com>,amsat-bb@AMSAT.Org
>Subject: Re: [amsat-bb] Arabic (?) music on FO-20 !!!
>Date: Tue, 22 Apr 2003 14:48:04 -0400
>
>1. If the downlink was 435.900, the uplink would be 145.800, +/- Doppler
>2. How does FM sound through an inverting transponder?
>
> >
> > From: "William Leijenaar" <pe1rah@hotmail.com>
> > Date: 2003/04/22 Tue AM 11:39:06 EDT
> > To: amsat-bb@AMSAT.Org
> > Subject: [amsat-bb] Arabic (?) music on FO-20 !!!
> >
> > Hi AMSATs,
> >
> > Anybody else hearing some (sounds to me) Arabic music, in FM on FO20 ???
> > I heared it yesterday afternoon (21 april) when the satellite was flying
> > over the area Israel, Turkye, Greece.... up to the north towards Europe.
> >
> > I made a copy of it with my mini-disc. Several moments the modulation 
>was
> > even noise free !!! The downlink was at abt. 435.900MHz, so the uplink 
>is at
> > abt. 145.900MHz.
> >
> > Anybody hear this before ? It must be a relative strong transmitter. I 
>can
> > not imagine some indoor system will provide such strong uplinks, and 
>noise
> > free !!
> >
> > When needed I will try to make a digital file of the minidisc-record and 
>put
> > it on internet. Maybe we can find the pirate :-)
> >
> > 73 de PE1RAH, William
> > ---
> >
> >
> >
> >
> >
> > _________________________________________________________________
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> > ----
> > Sent via amsat-bb@amsat.org. Opinions expressed are those of the author.
> > Not an AMSAT member? Join now to support the amateur satellite program!
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> >
>
>Scott Townley NX7U
>Gilbert, AZ  DM43di
>


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----
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