[time-nuts] manual request: Austron 2201A

Rob Kimberley rk at timing-consultants.com
Fri Jul 20 13:36:03 EDT 2007


The Meinberg antenna should work with the SatSync, although not tried one
out.

Rob 

-----Original Message-----
From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
Behalf Of Robert Atkinson
Sent: 20 July 2007 08:16
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] manual request: Austron 2201A

); SAEximRunCond expanded to false
Errors-To:
time-nuts-bounces+rk=timing-consultants.com+rk=timing-consultants.com at febo.c
om

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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