[IGSMAIL-6295] Re: Upgrades of AUCK, WGTN, MQZG, DUND, CHTI to Trimble NetR9 receiver

[Frederick Blume]

Dear John,
In our initial evaluation of the NetR9 we have found it to be more sensitive to RF interference from our Iridium data communications modems than NetRS.  This is not surprising given the increased spectral bandwidth of this and other all-constellation receivers, nor is it unique to the NetR9 - so far we've also seen it in a new Leica GR-10.  We're in the process of quantifying this further and looking into what other RF sources might affect these systems.  See this article for information on what we've observed so far:

http://facility.unavco.org/kb/questions/675/Update%3A+Iridium+%26+GPS%7B47%7DGNSS+Inteference


My recommendation would be to collect some data with the NetR9/Zephyr 2 at each site to make sure there are no RF sources that might affect the new setup before the hardware swap.  As you can see from our report using an old Zephyr with a NetR9 makes the problem go away, although it will affect the L5 SNR (you can still track L5 with a Zephyr 1, just with a lower signal strength).  So if you find poor poor GPS data quality with the NetR9/Zephyr 2, you could then test a NetR9/Zephyr 1.

Let me know if further information would be helpful and good luck with the new hardware,
Freddy Blume
====================
Dr. Frederick Blume
Sr. Project Manager
UNAVCO
6350 Nautilus Dr.
Boulder, CO  80301-5553
(303)381-7474
http://www.unavco.org
====================

On Nov 4, 2010, at 5:11 PM, John Beavan wrote:

> 
> Author: John Beavan 
> 
> Over the next few weeks to months we are planning to upgrade five New Zealand-based IGS stations to GNSS-capable Trimble NetR9 receivers with Zephyr Geodetic II antennas (TRM55971.00). 
> 
> These stations are currently runnning NetRS receivers and Zephyr Geodetic I antennas (except CHTI which already has a Geodetic II antenna). 
> 
> To provide some calibration of time series offsets at the equipment change we intend to run a Trimble 5700 with Zephyr Geodetic I antenna at a nearby (< 1 km) site for 3 days before and after each exchange.  We may not do this at CHTI since the installed antenna is already the new model. 
> 
> We believe these may be the first NetR9 receivers in the IGS network, so if anyone has any concerns about the planned upgrades please let me know. 
> 
> Best regards, 
> John 
> --------------------------------------------------------------------------------------
> Dr John Beavan, GNS Science - Te Pu Ao, 
> 1 Fairway Drive, PO Box 30368, Lower Hutt, New Zealand
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