[time-nuts] manual request: Austron 2201A

Robert Atkinson robert.atkinson at genetix.com
Fri Jul 20 07:15:52 UTC 2007


Hi,
Many of the Odetics SatSync receivers also used this scheme. I've had a
few of the receivers but never seen an antenna. Some were modified with
a Magellan OEM 5000 module and use a standard (12V) antenna.

Robert.

-----Original Message-----
From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
Behalf Of Magnus Danielson
Sent: 20 July 2007 00:12
To: time-nuts at febo.com; rk at timing-consultants.com
Subject: Re: [time-nuts] manual request: Austron 2201A

); SAEximRunCond expanded to false
Errors-To:
time-nuts-bounces+robert.atkinson=genetix.com+robert.atkinson=genetix.co
m at febo.com

From: "Rob Kimberley" <rk at timing-consultants.com>
Subject: Re: [time-nuts] manual request: Austron 2201A
Date: Thu, 19 Jul 2007 21:40:32 +0100
Message-ID:
<!&!AAAAAAAAAAAYAAAAAAAAAOYAZyOzV8ERq+LmT45ypI7CgAAAEAAAAHNkDDJzE/pPgmle
zQHl6CkBAAAAAA==@timing-consultants.com>

Hi Rob,

> I agree. When I looked at the Quantic numbers you gave me, I sort of
hit a
> mental block - not logical to me.
> 
> Meinberg's current GPS antenna has following characteristics
> 
> 10 MHz LO
> 35.4 MHz IF
> 12V - 18VDC Power
> 
> http://www.meinberg.de/download/docs/manuals/english/gpsant.pdf
> 
> For more info.

Lower cable damping at lower frequencies allows for longer cable runs.
Very
handy when considering putting GPS receivers into underground telecom
bunkers.
Fiber link is also a very good thing in those cases. Both is a must if
you
want to play in that leage, and Meinberg wants that.

Now, If you look at the Zarlink GP2015 GPS Frontend chip you will find
how
well it fits with this scheme. You apply 10 MHz to the chip, it PLL
locks a
1,4 GHz VCO and mixes down with that (1575,42 - 1400 = 175,42 MHz), then
it
goes for a filtering round and then comes back for the second mixer at a
tenth
of the VCO frequency, i.e. 140 MHz (175,52 - 140 = 35,42 MHz) again goes
out
for a filtering-round (through a SAW filter) and back in for a mixdown
with
31,11 MHz (actually 280 / 9 MHz) producing a 4,309 MHz signal which is
then
sampled at 5,714 MHz (actually 40 / 7 MHz) producing 1,405 MHz carrier
frequency in the 5,714 Msamples/s 2-bit datastream.

The Meinberg trick can be done by simply put one frontend chip in the
antenna
and another in the receiver. Both is fed the same 10 MHz clock but you
pick up
the signal after the 2nd mixdown stage and transport that IF over the
cable
and then toss in it at that place in the receivers frontend. The AGC
there will
automatically compensate for cable damping which happends around the 3rd
mixdown. The HF part of the frontend in the receiver it just kept as
dead
functionality. Same goes for the 3rd stage in the antenna.

Fairly clean and simple.

Cheers,
Magnus

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