[time-nuts] eBay GPS antennas
magnus at rubidium.dyndns.org
Sat Feb 17 08:33:00 EST 2018
A complicating factor with GLONASS is the frequency separation of the
satellites which causes several aspects of calibration issues.
I know they have changed operational aspects which have reduced
uncertainty significantly. This is also something that have been worked
at with the GPS system continuously.
It's a bowl of mixed issues.
However, the more systems and the more bands we use, the better we get
at finding discrepancies and mitigate them. The "all" system and
frequencies is however still very expensive.
On 02/16/2018 07:47 PM, Bob kb8tq wrote:
> Well, the interesting point about Glonass timing is that it is independent of the
> GPS empire. Galileo is another independent time source. Running a GPSDO
> linked to each one would let you inter-compare the time from each of them.
> Indeed I would *guess* that Galileo would do pretty well. Reports to date on
> Glonass have not been encouraging. It still might be interesting to do. Once
> Furuno releases the Galileo firmware, one of the Opus 7 based devices should
> be able to run each of them. uBlox or some of the others would also do the
> same thing.
>> On Feb 16, 2018, at 1:31 PM, Stewart Cobb <stewart.cobb at gmail.com> wrote:
>> FYI, Antcom and AeroAntenna are two manufacturers of high-quality
>> American-made GPS / GNSS antennas. Antcom's datasheets are confusing to
>> read, and AeroAntenna hides theirs behind a customer-login barrier, so most
>> of eBay doesn't know exactly what they are. This means that good antennas
>> are often available cheap.
>> For example, any AeroAntenna whose part number starts with "AT2775" is a
>> dual-frequency L1/L2 GPS antenna. AT2775-42 is a near-survey-grade antenna,
>> and one of them is available right now (item 263500294711) at a starting
>> bid of $20, after expiring yesterday with no bids at $25.
>> Several other AT2775 antennas are on eBay for under $200. Any of these
>> would be excellent for time-nut purposes.
>> IMHO, Glonass coverage is not useful for precision timing. If you don't
>> have a good enough antenna installation to get continuous GPS coverage,
>> you're not really doing precision timing. If you are getting continuous GPS
>> coverage, Glonass doesn't add anything.
>> Disclaimer: I have no relationship to either company mentioned, other than
>> previously being a satisfied customer of both companies. I have no
>> connection to any sales currently listed on eBay.
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