On 11/22/19 2:29 PM, Hal Murray wrote:
j...@febo.com said:
I like the idea of inserting attenuation until the SNR or Cn values start to
go down. That may be the most practical solution.
Inserting attenuation is a good trick for the tool box. It is also used to
measure error rates on fiber
Am 22.11.19 um 23:29 schrieb Hal Murray:
j...@febo.com said:
I like the idea of inserting attenuation until the SNR or Cn values start to
go down. That may be the most practical solution.
Inserting attenuation is a good trick for the tool box. It is also used to
measure error rates on fiber
j...@febo.com said:
> I like the idea of inserting attenuation until the SNR or Cn values start to
> go down. That may be the most practical solution.
Inserting attenuation is a good trick for the tool box. It is also used to
measure error rates on fiber links.
With a reasonable fiber
You can get the data from
The manufacturer
or from some calibration database like NOAA
https://www.ngs.noaa.gov/ANTCAL/#
Or geo++
Or the list of antennas built into the post processing software.
/Björn
Sent from my iPhone
> On 22 Nov 2019, at 19:02, Bill Dailey, MD, MSEng, MSMI
> wrote:
Interesting. No, there was no data with it.
On Fri, Nov 22, 2019 at 12:00 PM Björn wrote:
> The N for North is because the phase center offsets are not symmetrical.
> With a convention to orient the antennas the same way the offset could be
> corrected.
>
> /Björn
>
> Sent from my iPhone
>
> >
I believe that's to avoid errors from phase center offset -- when the antenna
calibrations are done, the measurements are taken with the antenna aligned that
way so aiming it in the fields ensures releatability.
On Nov 22, 2019, 12:01 PM, at 12:01 PM, Bill Dailey wrote:
>I would like to tag on
Hi
If your antenna has test data associated with it (or even if it does not) there
may / will
be differences in the phase response for various angles both in the vertical
and horizontal
planes. Indeed some antennas have very minor changes vs angle and others move
quite a bit.
To keep this
The "N" indeed points north. This is because these large
reference-station choke-ring antennas are often calibrated for phase
center with respect to north. Did you get the phase center calibration
data with your antenna?
Pointing the "N" towards north will not have much effect on timing
The N for North is because the phase center offsets are not symmetrical. With a
convention to orient the antennas the same way the offset could be corrected.
/Björn
Sent from my iPhone
> On 22 Nov 2019, at 17:07, Bill Dailey wrote:
>
> I would like to tag on to this. I have a large Leica L1
I would like to tag on to this. I have a large Leica L1 choke ring antenna.
It has an indicator for “N”. Not sure why. I placed it on the roof without
respect to directionality. I will rotate it with “N” facing north in a month
or so to see if there is any effect.
Bill Dailey
Negativity
Hi
If you have a survey device like a Trimble NetRS then you *must* have a high
gain antenna.
If you want to feed it from the Trimble, you need an antenna that runs on 12V.
It also needs to
be an L1 / L2 antenna.
If all you have a TBolt timing receiver, then you want a 20 db gain antenna
Most modern GPS receivers are very quiet even barefoot. So, one could
argue that one should
not have much more LNA gain in the antenna than required to make up for
feedline loss, which
should be easily calculable. While excess gain in the antenna can improve
overall system noise
figure a small
So concensus is, 50dB gain antenna is too much gain, unless feed line is
too long, reception is poor, or there are other circumstances extra gain is
desired?
---
(Mr.) Taka Kamiya
KB4EMF / ex JF2DKG
On Thursday, November 21, 2019, 3:00:14 PM EST,
John Ackermann N8UR writes:
> One related question, especially with mixed systems -- how do you tell
> if you have optimum signal level at the receiver?
>
> Most show some sort of SNR or Cn value. What should we look for? What
> are the indication of *too much* signal? One issue in particular
Hi
That is indeed the gotcha. Once you get past a certain amount of gain in the
preamp, the C/N levels don’t change enough to notice. Looking today vs looking
tomorrow is unlikely to be of any help if you are after a fraction of a db.
About the only way to check would be to fast switch an
John Ackermann N8UR writes:
> One related question, especially with mixed systems -- how do you tell
> if you have optimum signal level at the receiver?
I don't think you're going to figure out an _optimum_ gain without
proper measurements along the whole signal chain. As a proxy, the
reported
Bob, this is a great summary, thanks!
One related question, especially with mixed systems -- how do you tell
if you have optimum signal level at the receiver?
Most show some sort of SNR or Cn value. What should we look for? What
are the indication of *too much* signal? One issue in particular
Hi
Way back in time, the first gear out there to use what we now look at as
“normal” antennas
was survey gear. For various reasons they decided on a 12V power supply and 40
to 50 db
of gain in the preamp mounted in the antenna. They also got into L1 / L2 pretty
quickly.
A bit later the cell
Like many things, price does not necessarily reflect a better antenna,
however there are differences between antennas.
One difference is in the quality of the filters in the antenna itself.
This matters more when one is mounting an antenna at a communications site
than say at a home timing lab.
I have been looking antennas. Prices seem to range less than 30 dollars to
more than 500 dollars. Some are 20db gain and some are 40 db gain. Some are
specified as marine use only. Some are specified as timing use. Some doesn't
say anything at all. Power supplies are different.
Other than
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