GPS antenna subjective tests


#1

Guys,

We did some subjective tests for GPS antennas with following antennas :

1- Mfg: Taoglas, Digi-key p/n: 931-1406-ND
AGGBP.25B.07.0060A
Description ANT MOD GPS 60MM 2STAGE MHFI SAW

2- Mfg: Abracon LLC, Digi-key p/n: 535-12616-ND
APAM1866YA18
Description ACTIVE INTRNL ANT 1575.42MHZ GPS

3- Mfg: Yageo, Digi-key p/n: 311-1541-ND
ANT2525JB08B1575A
Description ACTIVE ANT GPS USE 25X25X4

4- Mfg: Inventek, Digi-key p/n: 1475-1008-ND
ACTPAT254-01-IP
Description ANT GPS CERAMIC U.FL

AT Commands used to activate and check the TTFF:
Make sure GPS is enabled (it is enabled by default)
AT!CUSTOM? should show GPS enabled
AT!GPSAUTOSTART=1,1,254,1,1000
Returns OK
AT!GPSSTATUS? should show:
1980 01 06 6 00:01:10 Last Fix Status = SUCCESS
1980 01 06 6 00:01:10 Fix Session Status = ACTIVE
TTFF (sec) = 43

room with wondows on 3 sides WP85
1- Taoglas Antenna
a. TTFF:186 sec
2- Yageo
a. TTFF=32 Sec
3- Inventek
a. TTFF=56 Sec
4- Abracan
a. TTFF=43 Sec
TTFF=218 sec with Roof Mount type Ant at my desk
Ambleside room:
1- Taoglas Ant.
a. TTFF=71 sec

Wp76 module
1- Taoglas Ant
a. TTFF=43 Sec
2- Yageo Ant.
a. TTFF=75 Sec
3- Inventek Ant.
a. TTFF=70 Sec
4- Abracan Ant.
a. TTFF=41 Sec
5- Taoglas Ant (second time)
a. TTFF=45 Sec
WP76 (another module, programmed, first time use)
1- Taoglas Ant
a. TTFF=91 Sec
2- Yageo Ant
a. TTFF=52 Sec
3- Inventek Ant
a. TTFF=47 Sec
4- Abracan Ant
a. TTFF=44 Sec
5- Taoglas Ant (second time)
a. TTFF=61 Sec


Unable to get Positioning fix with LAF 17.10
#2

Probably there is an explanation for such miscellaneous results. Number of visible satellites can vary during time, for example now at my place is changing from 11 to 7 sats in one hour. To check momentary conditions, there is a nice tool:
http://www.trimble.com/GNSSPlanningOnline/#/NumSats
(maybe needs IE and Silverlight)

Mirek