I received the note below from Ernie Peres in Germany which reports an effect consistent with an occasional phase jump in the 1 PPS output from a M12+ rcvr, perhaps related to DGPS corrections.  The DGPS sats Ernie sees from his location are part of the EGNOS system.

The DGPS sats visible to me (sats #35,47 according to my Garmin V) are part of the WAAS system and I haven't noticed the phase jump effect with an M12+.

I wouldn't  really expect to since the M12+ is not WAAS/EGNOS "enabled".

However, something more subtle might be occurring.  I wonder if anyone else has noticed such an affect or has any ideas.

Brooks

------------------note from Ernie----------------------------
.....I am using  a Motorola M12+ timing  GPS eng  board to drive the W5OJM controller board and  the high prec OCXO. I have also bought a Garmin V handheld unit just for playing around and noticed that it displays " new " sats.....ie nbr 33 and 37. but the signal bar for this sats were gray instead of black on the display.
Later I learned that this new sats are the  AOR-E sat nbr 120 and the ARTEMIS sat nbr 124, and also noticed that sat 33 is transmitting DGPS signals because the
GARMIN  V  /  WAAS enabled / receiver displayed  " D " letters in the signal strength bar. Also the TAC32 program displayed DGPS received and  station ID "0000" age 0.........

When I see this sats on the GARMIN receiver the same time your GPS controlled board indicates a phase jump... I am using DG4RBF software to plot EFC and phase error......
Did you heard similar situation?
I do not know if this 2 sats are visible from the US but it should be because the position from my home / Frankfurt/M,  Germany/  AOR-E  EL... 28 deg. and
AZ.... 214 deg.  the 37 sat ARTEMIS nbr 124  El...27 deg      AZ....164 deg.

Also I have built other type of GPS controlled OCXO  the so called "analog" version where the  JUPITER GPS eng board 10kHz signal is PLL-ed the OCXO, and
also noticed  on the EFC voltage a small variation....

Did any other person reported similar problem?
Based on the internet info this WAAS not yet fully operational. It is just a testing procedures ????????  or what is the future of this kind of OCXO locks?
Best regards,

Ernie    HG5ED
------------------------end of Ernie---------------------------

I Might be seeing the same thing you (Ulrich, Ernie, Brooks) are seeing,
although I would not attribute it to WAAS or EGNOS, as I am not using a
receiver that is enabled for differential corrections.

I am using the 1 pulse-per-second output from a Motorola M12+ Timing
receiver (M12+T) to disipline my 10 MHz frequency reference, which is a
Stanford Research Systems (SRS) model PRS-10 rubidium standard. (The
M12+T is mounted together with its antenna on a pole above the roof of
the apartment building in which I live.)

I have been observing the phase diference between the M12+T pulses and
the PRS-10 10 MHz output (counted down to 1 Hz) using a SRS model SR620
time interval counter.  The SR620 is set to display the means and
standard deviations of N-sample "measurements" (teminology from the
SR620 instruction manual) on an oscillosope. The oscilloscope shows a
graph of most recent 250 of these 600-sample measurements. I have set N
= 500, so 250 measurements of these measurements amounts to 250*500 =
125 000 s, or somewhat longer than a day.

The jitter (stamndard deviation) of the 500-sample measurements is
consistently about 10 ns.

The time interval between the two 1 PPS signals (that is, the phase
difference between the two 1 PPS outputs -- one from my PRS10 house
oscillator and the other from the M12+T GPS receiver) varies over the
course of the day.  For example, over the last day or so there were
maximum and minimum phase differences as follows:

measurement # 238:          +60 ns (+59.797 ns)
measurement # 302 (250+ 52): -48 ns (-47.799 ns)
measurement # 409 (250+159): +70 ns (+70.250 ns)

The interval between the two maxima of the phase differences is about
(409-250)*500 s = 86500 s, or about a day.

This suggests to me that the M12+T output might be exhibiting two phase
jumps each day, one positive and one negative.  These phase jumps would
perturb the PRS10's internal phase lock loop (PLL) that disciplines the
PRS10 to agree with GPS time. (I have set the PRS10's PLL "PT" parameter
to 9, which gives the PLL a time constant of about 3 hours. I am
reluctant to set the PLL time constant to a greater value until I have
an M12+T with Rich Hambly's hardware sawtooth correction to the 1 PPS
output.)

To view this phenonemon in more detail, I really should write some
software to interface with the PRS10 and record the time stamps of the 1
PPS pulses from the M12+T.

I'm also trying to scrape the money together to buy one of Richard
Hambly's "CNS Clock II" receivers with his "High Performance PPS"
options that provides a hardware sawtooth correction to its M12+T's 1
PPS output.  That will probably reduce the jitter I see over a
100-second interval from about 10 ns to something less, perhaps 2 or 3
nanoseconds. It would also let me set a longer time constant on the
PRS10's PLL by which it synchs its 10 MHz oscillator to agree with GPS time.

However, upgrading my M12+T to one with the hardware sawtooth correction
on the 1 PPS output would not, I think, have any effect on the
twice-per-day phase jumps that I think we are observing.

--
James Maynard, K7KK
Salem, Oregon, USA