Locus Antenna Specs
Posted By C T on 4/24/2002 at 8:58 PM

Anyone know the antenna number for the Locus. Wanted to look at the specs on the NGS site. Thanks.

Re: Locus Antenna Specs
Posted By Mike Margolis_ on 4/24/2002 at 9:50 PM

it is 800372, but not on the NGS site.

Double click on any Locus observation in the time line, and then hit the 3 dot box to the right of Antenna Properties, there you'll find the factory numbers for the Locus antenna.

Mike: Locus Antenna Specs
Posted By C T on 4/24/2002 at 10:46 PM

But what is the NGS number for the Locus? Mainly interested in the labeling diagram for the Locus antenna. Thanks Mike.

Re: Locus Antenna Specs - Not on NGS List
Posted By James Webb on 4/25/2002 at 6:57 AM


Re: Locus Antenna Specs
Posted By jerry wahl on 4/25/2002 at 9:23 AM

I suspect that what Mike intended to say was that it is not on the NGS site.

Although my first interpretation was that the number 800372 was not the number for it on the NGS site.

- jlw

PS: if that is the case maybe thales could make up a dummy locus with the antenna and a connector on the side and submit it 'as an antenna' to NGS.
Modified By jerry wahl on 4/25/2002 at 9:25 AM

Re: Locus Antenna Specs
Posted By Bob LeMoine on 4/25/2002 at 2:29 PM

As a general rule, NGS does not test L1 - Single Frequency GPS Antennas, more specifically Ashtech has not submitted any Locus receivers to NGS and requested any Electrical Phase Center testing on the combined Locus Antenna/Receiver.

Re: Locus Antenna Specs
Posted By Jim Frame on 4/25/2002 at 3:37 PM

Anyone know why they bent the rule for the PM2? Does is share an antenna with any L1/L2 products?

Good Question Jim--Hey Ashtech
Posted By C T on 4/25/2002 at 3:43 PM

Why not send a Locus to NGS for testing? Inquiring minds need to know.

Re: Locus Antenna Specs
Posted By Bob LeMoine on 4/25/2002 at 5:30 PM

Best of my knowledge, the PM2's L1 Antenna has not been tested by NGS.
Lets not confuse Mechanical Phase Center values with Electrical Phase Center values.

Receivers Manufacturer's and/or Antenna Manufacturer's produce the Mechanical values that typically include the Antenna
diameter, radius and other mechanical characteristics, technical dimensions particular to the manufacturing of the antenna.

Electrical Phase Center data is typically tested & published by NGS, but can also include other scientific/University type organizations. This data details the electrical characteristics, or electrical signature of the GPS antenna.

For those that are interested in the NGS
GPS Antenna testing procedures, please review the NGS Technical paper on GPS Antenna Calibration, this paper can be found on NGS's web site. It's interesting
reading, describes the testing procedure.

Receivers like Locus & PM2 log data internally, part of the NGS testing procedure requires logging GPS data with receivers that have external Serial Ports
External Frequency and 1 PPS connections, features that L1 receivers like Locus & PM2 simply do not have.

Re: Locus Antenna Specs
Posted By Rod Johnson on 4/25/2002 at 7:10 PM

As I understand the NGS test procedure, the antenna being tested is always connected to an Ashtech Z-12 (good choice!). The data collected is processed and compared to an identical baseline using choke ring with Ashtech Z-12.

The Ashtech Pro-Antenna (ProMark2, 110454) was indeed tested by NGS. It's not the first time they've done an L1 antenna (Novatel, Aero, and Ashtech) and hopefully not the last. Locus was not tested because of the difficulty of de-coupling the Locus internal antenna from the receiver itself. The values for the Locus are mechanical offsets only.

Hope this helps clear up the questions.

Rod Johnson,
Ashtech Marketing

Re: Locus Antenna Specs
Posted By jerry wahl on 4/25/2002 at 8:54 PM

Like I said above, one could take the locus housing, remove the receiver or bypass it to an antenna connector on the side and call it an antenna and get it calibrated. Couldn't one?