[time-nuts] Choke Ring Pictures

[WarrenS]

Brian wrote:

> "There were also comments about surveying and timing antennas."
Those may of been from me, unsuccessfully trying to make a point of the 
difference between what is 'Best' and what is 'GOOD enough'.

> "about every national timing laboratory uses choke ring antennas.   ... 
> for timing stability reasons."
Then again they also have multiple CS and Just their Antenna budget is 
likely more than the annual income of most time nuts.
Can you do a test to show IF there is ANY improvement for the AVERAGE time 
nut when compared to a well setup (Tbolt) GPSDO using a TacoSalad antenna?

Would be interesting to see a plot of cost vs. performance for the various 
antenna types,
Scaled to show the performance improvement that the average Time nut would 
see.
The TacoSalad antenna, originally cost me a total of $7.95, And took under 
30 seconds to build.
That cost should be discounted because those parts had been considered just 
throw away junk up until now.

ws

**********************

----- Original Message ----- 
From: "Brian Kirby" <kilodelta4foxmike at gmail.com>
To: "Discussion of precise time and frequency measurement" 
<time-nuts at febo.com>
Sent: Monday, March 15, 2010 2:09 PM
Subject: Re: [time-nuts] Choke Ring Pictures


> Dr. Clark passed on a tip that I used.  Put the funnel in a microwave oven 
> and run it and see if the funnel warms up.  If it warms up, you do not use 
> it.  I do not know what type of plastic the funnel was made out of; it was 
> white, semi-transparent.
>
> There were also comments about surveying and timing antennas.  If you 
> investigate about every national timing laboratory uses choke ring 
> antennas.  Some enclose the antenna unit and they temperature control it. 
> They do this for timing stability reasons.
>
> The commercial timing antenna is bullet shaped and is operated without a 
> ground plane.  They are patch antennas.  When there is not ground plane, 
> the antenna picks up best from the overhead and less towards the horizon. 
> These antennas usually have a lot more gain (30-50 db vs most normal 
> antennas in the 15-25 db range).
> Also in surveying, we cut off the horizon at 15 degrees in software.  A 
> free Army Corp of Engineering manual on GPS Surveying is at 
> http://140.194.76.129/publications/eng-manuals/em1110-1-1003/toc.htm
> The main difference in surveying and timing is in surveying they use the 
> carrier phase method, were in timing most use a solution derived from the 
> processing of the coarse acquisition code, in were the receiver is in a 
> fixed over-determined position .  Some timing labs are using carrier phase 
> method, when they need more resolution.
>
> Brian - KD4FM
>
****************
>>warrens wrote:
...
>> Preliminary results for the Taco Dish GPS antenna as an indoor antenna 
>> are  looking good.
>> Certainly worth considering if your GPS antenna is stuck indoors, 'Out of 
>> the rain in the living room'.
>> I find it best to rise it up near the ceiling such as on an upper shelf 
>> with nothing above it.
>> It would be hard to tell the difference between the GPSDO performance 
>> obtained from this or the Best outdoor antenna if using a Tbolt set to 
>> the  standard default settings.
>> Picture attached
>>
>> ws
>>
> **************