On 18 Feb 2015 04:20, Tom McDermott tom.n...@gmail.com wrote:
Hi Dave - agree that VNA is one good way to measure the delay. If
required
accuracy is less than about
0.5 nsec, then Tx antenna to Rx antenna mutual impedance starts to become
an issue.
I don't see why. The two antennas can (and
On Wed, 18 Feb 2015 07:24:32 -0800
Jim Lux jim...@earthlink.net wrote:
[1] http://miniradiosolutions.com/minivna-tiny
And tough to find any substantive information on the hardware design. I
poked around for a few minutes, but all I was able to find was software
user manuals, but no
On Thu, 19 Feb 2015 10:51:04 +0100
Attila Kinali att...@kinali.ch wrote:
When i had one on my desk, i opened it up, but apparently i forgot to take
pictures. From what i remember, i think it works either similar to the
VNWA design done by DG8SAQ[1,2] or by N2PK[3]. The tinyVNA can only do
On 2/19/15 1:59 AM, Attila Kinali wrote:
On Thu, 19 Feb 2015 10:51:04 +0100
Attila Kinali att...@kinali.ch wrote:
When i had one on my desk, i opened it up, but apparently i forgot to take
pictures. From what i remember, i think it works either similar to the
VNWA design done by DG8SAQ[1,2]
On 2/18/15 1:49 AM, Attila Kinali wrote:
You could try tinyVNA[1]. I have used it once, it has some quirks
(it's half hobby, half commercial project and that shows) but works
otherwise. I have no idea how accurate it is.
Attila Kinali
[1]
On Tue, 17 Feb 2015 18:33:24 -0800
Tom McDermott tom.n...@gmail.com wrote:
Hi Dave - agree that VNA is one good way to measure the delay. If required
accuracy is less than about
0.5 nsec, then Tx antenna to Rx antenna mutual impedance starts to become
an issue. Above about
1 nsec error
just fine.
Tom Holmes, N8ZM
-Original Message-
From: time-nuts [mailto:time-nuts-boun...@febo.com] On Behalf Of Tom McDermott
Sent: Tuesday, February 17, 2015 9:33 PM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] GPS active antenna delay ?
Hi Dave - agree
Hi:
One of the chirp receivers I worked with was connected to the audio output of a
shortwave receiver.
Since chirp transmitters sweep frequency (typically 2 to 30 MHz) you don't tune in the frequency domain but rather in
the time domain and compare to a GPS based 1 PPS.
This time difference
Hi
By far the simplest way to do this is to use a broadband passive antenna with a
short cable. They
are a $10 item on the auction sites. Compare whatever comes out of the GPS
running off the cheap antenna to your
“full system” pps offset. What you are doing with this comparison is no
thol...@woh.rr.com said:
How accurately do you need to know the delay? For absolute time, it is
important, but it doesnât really help much with position since the
calculation doesn't know which direction your receiver is located from the
antenna.
GPS tells you the location of the
Hi Dave - agree that VNA is one good way to measure the delay. If required
accuracy is less than about
0.5 nsec, then Tx antenna to Rx antenna mutual impedance starts to become
an issue. Above about
1 nsec error probably most of these can be ignored. No access to a vector
VNA that works at 1.5
On 7 Feb 2015 19:18, Tom McDermott tom.n...@gmail.com wrote:
Has anyone on the list measured or otherwise estimated the active antenna
delay including the amp and filters?
-- Tom, N5EG
I have never done this, but suspect that using a VNA is the best way to
go. With a simple passive dipole
On Sat, 7 Feb 2015 10:07:44 -0800
Tom McDermott tom.n...@gmail.com wrote:
While compensating for cable delay is relatively straight forward by
measuring the length and compensating for
the velocity factor, a question is: how much amplifier / filter group delay
is to be expected within the
Attila,
On 02/08/2015 11:11 AM, Attila Kinali wrote:
On Sat, 7 Feb 2015 10:07:44 -0800
Tom McDermott tom.n...@gmail.com wrote:
While compensating for cable delay is relatively straight forward by
measuring the length and compensating for
the velocity factor, a question is: how much amplifier
On 2/8/15 2:11 AM, Attila Kinali wrote:
On Sat, 7 Feb 2015 10:07:44 -0800
Tom McDermott tom.n...@gmail.com wrote:
While compensating for cable delay is relatively straight forward by
measuring the length and compensating for
the velocity factor, a question is: how much amplifier / filter group
I think that the surplus HP/Agilent GPS splitters may have an SAW
filter. If so, measuring the delay of one of those could yield at least
an approximation.
I may have that data laying around; I'll do some digging.
John
On 02/08/2015 05:11 AM, Attila Kinali wrote:
On Sat, 7 Feb 2015
j...@febo.com said:
OK, so I had an HP 58535A two-port GPS splitter handy and put it on the
VNA. It clearly has a filter of some sort, as shown by the S21 frequency
response. The delay at the center of the passband is about 21ns, and it
increases to about 26ns at the edges.
Thanks.
It
OK, so I had an HP 58535A two-port GPS splitter handy and put it on the
VNA. It clearly has a filter of some sort, as shown by the S21
frequency response. The delay at the center of the passband is about
21ns, and it increases to about 26ns at the edges.
That delay consists of the physical
Hi all.
The papers are:
1) SAW Filter Modeling in MATLAB for GNSS Receivers, S.H. Abbas, et al.,
IJECE Oct 2013, ISSN: 2088-2078
The authors de-embed the group delay using FFT and MATLAB. Eyeball about
15-20 nsec. for a pretty wide filter.
2) The Effects of SAW Group Delay Ripple on GPS and
I have a white-hockey-puck style active GPS antenna, probably about 1998
vintage with no markings except 'Made in Mexico'.
While compensating for cable delay is relatively straight forward by
measuring the length and compensating for
the velocity factor, a question is: how much amplifier / filter
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