[time-nuts] New timing receivers?
w2gps at cnssys.com
Sun Apr 27 20:10:42 UTC 2014
There is an important error in your message below. The Motorola designed
M12M receiver is still in popular and in full production mode. You can get
them from Synergy Systems, LLC in San Diego. They are very friendly to
time-nuts members. The M12M has been used continuously by commercial
companies in the timing community since iLotus took over production from
Motorola in 2006. The timing characteristics of the M12M are basically the
same as the Motorola M12+ but the M12M has a wider input gain range (10 to
50 dB) and a faster Time To First Fix (TTFF) and it continues to be
available from stock.
Synergy also has the SSR-6T series of receivers that have a uBlox module but
emulate the M12M commands and messages. These are plug in replacements for
the M12M. The emulation is not total but has most of what you need from the
M12M command set. These boards support some additional commands including
one that puts the receiver in uBlox binary message mode at 9600 baud. These
boards are very useful to those wanting the improved performance of the
uBlox modules but do not want to rewrite all their application software.
They are also useful for those migrating from the Motorola world to the
uBlox world but don't want to do it all at once.
Finally, Synergy has the SSR-6Tru which is a uBlox receiver on a PC board
that is the same size as the M12M and plugs into an M12M slot but
communicates only in uBlox's binary language at all baud rates supported by
the uBlox module.
From: Tom Van Baak [mailto:tvb at LeapSecond.com]
Sent: Sunday, April 27, 2014 9:45 AM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] New timing receivers?
For a nice comparison of the M12+T, M12M, and ublox-6T, start with page 34,
and especially note the ADEV plot on page 40:
The ublox-6T performs at least as well as the M12+T does. They are both in
the 1 to 2 ns/day ballpark. The advantage is that the 6T is a production
part and the M12+T and M12M are no longer made. So that's why commercial
users have been forced away from the Motorola or iLotus parts. But amateurs
still grab any M12 they can find because they are so good, and now dirt
cheap on the surplus market.
Note that Rick Hambly created the (Synergy) SSR-6T, which is a ublox-6T on a
M12+T compatible PCB. Using a PIC it transparently translates between
motorola and ublox binary so that the board is h/w and s/w compatible with
any M12+T; a drop-in replacement. The plots you see in that PDF are the
result of comparing M12+T and ublox-6T for this project.
The bottom line is if you're looking for a low-budget but very
high-performance GPS timing receiver, the M12+T is still a favorite among
amateurs. If you're looking for something more modern, or a GPS timing
receiver to use in quantity, or want an architecture that does or will
accommodate Galileo and GLONASS, and are willing to pay the higher price,
then check out the ublox-6T.
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