[time-nuts] Trimble Thunderbolt - Receive Sensistivity

J. L. Trantham jltran at worldnet.att.net
Thu Aug 28 23:39:22 EDT 2008


You are correct about the elevation mask and it, too, can be changed via
TBoltMon.  However, the Thunderbolt and the Z3816A both had the elevation
mask set to 10 degrees.  They were running off the same HP timing antenna
with 25 feet of RG-58 to a 58536A Symmetricom GPS distribution amplifier and
then a short RG-58 jumper to the respective receivers with N to BNC adapters
everywhere and BNC connectors on the RG-58.  Clearly not the most ideal
cable system but it works for comparison.

Joe


-----Original Message-----
From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com] On
Behalf Of John Miles
Sent: Thursday, August 28, 2008 9:49 PM
To: Discussion of precise time and frequency measurement
Subject: Re: [time-nuts] Trimble Thunderbolt - Receive Sensistivity

The elevation mask might also come into play.  Ordinarily you don't want to
consider input from satellites too near the horizon, as terrestrial features
can distort the signal's timing.

I think it can be stated with confidence that there's nothing wrong with a
(normally functioning) Thunderbolt's sensitivity specs, and that putting
random amplifiers, splitters, and such into the antenna lead might be
counterproductive.

-- john, KE5FX

> -----Original Message-----
> From: time-nuts-bounces at febo.com [mailto:time-nuts-bounces at febo.com]On
> Behalf Of J. L. Trantham
> Sent: Thursday, August 28, 2008 7:39 PM
> To: 'Discussion of precise time and frequency measurement'
> Subject: Re: [time-nuts] Trimble Thunderbolt - Receive Sensistivity
>
>
> When I compared the function of the Thunderbolt to my Z3816A, the
> number of
> tracked satellites was smaller on the Thunderbolt.  However, the Signal
> Level Mask is set to 4.0 on the Thunderbolt.  After I reset it to
> 1.0, they
> tracked the same (and number of) satellites.
>
> This I did with TBoltMon under 'Setup', 'GPS Receiver' which takes you to
> 'Receiver Configuration'.  Change the Signal Level Mask (AMU) to
> the desired
> number then 'Set Receiver'.  I also hit 'Save Segment' though I
> do not know
> if this is a required step.
>
> Joe


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