[time-nuts] Thunderbolt reception problems

[WarrenS]

Maybe something too basic many too say,  but did you lower the Tbolts "signal level mask AMU" setting?
Default is 3, set to 1 or 2  so that it will accept lower level signals


----- Original Message ----- 
From: <SAIDJACK at aol.com>
To: <time-nuts at febo.com>
Sent: Saturday, November 21, 2009 11:40 AM
Subject: [time-nuts] Thunderbolt reception problems


> Hi guys,
> 
> some weeks ago we talked about reception problems on Trimble Thunderbolt  
> units. I finally took the time to download the Trimble monitor again, and get 
> my  unit locked again. Here is what I found:
> 
> The unit was running continuously for the last months, but wasn't  locked. 
> Using the Trimble monitor, I restarted the unit, now connected  directly to 
> my antenna, then after the survey was done let it run from my  antenna 
> splitter.
> 
> This works, but just barely. I use an Agilent 58512A amp, followed by a  
> Mini Circuits ZB4PD1-152-75+ 1-to-4 passive splitter.
> 
> In the attached plot a JLT FireFly-IIA and the Thunderbolt are both running 
> from the same Mini Circuits splitter. The Antenna sense circuit in the  
> Thunderbolt is happy, but the signal strength is just at the threshold of  
> working. The Sats kick in and out. Please see the attached screen  shot.
> 
> At the same time the FireFly-IIA receiver is tracking 11 Sats with perfect  
> signal strengths (up to 45dB+ C/No), from the same feed.
> 
> The difference in receiver performance is quite clear. Unfortunately I  
> have only a single antenna, so need to run the Thunderbolt from a  splitter.
> 
> One can also see two more interesting tid-bits in the screen shot: the  
> FireFly-IIA is tracking and using WAAS Sat PRN 48 (PRN 51 goes in and out of  lo
> ck due to a chimney being in the way), and it is showing true MSL rather 
> than  just GPS Height.
> 
> Thanks for the help,
> bye,
> Said
> 
>