GPS 1PPS signal

[Snail Instruments]

At 08:09 AM 4/15/08, you wrote:
>http://www.sectron.cz/?co=produkty&akce=&ref=31&sec=32&produktid=707 )
>se pise ze signal 1PPS, ktery z nich leze neni vhodny pro synchronizaci
>oscilatoru. Tusite nekdo prosim proc? Mysli se tim obecne vlastnosti
>(i kdyz ty tak spatne nejsou) GPS 1PPS signalu, nebo neco konkretniho
>u toho cipu?

Tohle jsem obdrzel jako vysvetleni. Podstatna je predevsim posledni 
veta - presnost 1pps signalu neni nijak charakterizovana ani zarucovana.

Even though the SiRFstarIII does output a 1PPS, it is NOT a timing receiver.

Timing Receivers have automatic survey where the position is averaged 
over 24 hours.  SiRFstarIII does not have that

Timing receivers lock the position after 24 hours and use that to 
further smooth timing. SiRFstarIII does not do that.

Timing receivers perform continuous outlier tests to detect SVs that 
are out of spec. SiRFstarIII does not do that

Timing receivers can maintain a 1PPS with only one SV. SiRFstarIII 
does not do that.

Timing receivers allow the 1PPS pulse to be advanced or retarded. 
SiRFstarIII does not do that.

Timing receivers have a 1PPS that is characterized over a variety of 
test conditions, temperature changes, satellite visibility, startup, 
flywheeling, etc. and the 1PPS accuracy can be referenced back to NIST.

The 1PPS pulse from ANY SiRF GPS receiver has not been so characterized.

In addition SiRF makes no claims or guarantees of 1PPS performance ? 
the product is not tested for 1PPS nor characterized for 1PPS behaviour.

J. Hanzal