The F10T looks interesting, but from the datasheet it is missing a few
maybe important features compared to the ZED-F9T:

-- L1/L5 bands only (no L2 option)
-- only one TIMEPULSE output (could be a very big deal)
-- only one EXTINT input (probably not a big deal)
-- I/O appears to be solely via one UART -- no native USB, no I2C/SPI

A lot of the pins used in the NEO-M8/9 modules are listed as "reserved".
I don't know whether the limitations are the result of cramming a
dual-freq receiver into the NEO form factor, of if they're for product
differentiation.

John

On 6/21/23 10:00, Erik Kaashoek via time-nuts wrote:

Hi All;
There is one NEO F10T breakout board I have seen.
https://www.ardusimple.com/product/simplegnss-timing/
[https://www.ardusimple.com/wp-content/uploads/2023/04/NEO-F10T_top.jpg]https://www.ardusimple.com/product/simplegnss-timing/
simpleGNSShttps://www.ardusimple.com/product/simplegnss-timing/
L1/L5/E5a GNSS receiver with submeter location accuracy, nanosecond timing accuracy and RAW data for postprocessing PPK. Based on u-blox NEO-F10T.
www.ardusimple.com
UBLOX has a eval software that is very useful, but has a few bugs.l
Cheers;

Tom Knox
SR Test and Measurement Engineer
Phoenix Research
4870 Meredith Way Apt 102
Boulder, Co 80303
Formerly of:
357 Fox Lane
Superior Co 80027
303-554-0307
actast@hotmail.com

https://www.thedenverchannel.com/news/marshall-fire/superior-man-moving-forward-after-losing-dream-research-lab-during-marshall-fire

"Peace is not the absence of violence, but the presence of Justice" Both MLK and Albert Einstein

From: John Ackermann N8UR via time-nuts time-nuts@lists.febo.com
Sent: Wednesday, June 21, 2023 8:37 AM
To: time-nuts@lists.febo.com time-nuts@lists.febo.com
Cc: John Ackermann N8UR jra@febo.com
Subject: [time-nuts] Re: What GNSS module to buy for a good time reference?

The F10T looks interesting, but from the datasheet it is missing a few
maybe important features compared to the ZED-F9T:

-- L1/L5 bands only (no L2 option)
-- only one TIMEPULSE output (could be a very big deal)
-- only one EXTINT input (probably not a big deal)
-- I/O appears to be solely via one UART -- no native USB, no I2C/SPI

A lot of the pins used in the NEO-M8/9 modules are listed as "reserved".
I don't know whether the limitations are the result of cramming a
dual-freq receiver into the NEO form factor, of if they're for product
differentiation.

John

On 6/21/23 10:00, Erik Kaashoek via time-nuts wrote:

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To unsubscribe send an email to time-nuts-leave@lists.febo.com

On 6/21/23 7:37 AM, John Ackermann N8UR via time-nuts wrote:

I'm not sure no L2 is such a big deal - going forward, people are
pushing to L5. It's better protected spectrum management (adjacent user)
wise, it has 3dB more power than L1, and longer spreading codes.   The
only hiccup is that it's only live on 17-18 satellites, 24 by 2025.  L2
has less power than L1, but the longer codes for L2C should make up
for that.

A question would be whether a L1, L2 receiver uses the L2C, or whether
they are just doing phase retrieval on the L2 unmodulated carrier (older
satellites). Or some sort of codeless processing.

There's also a somewhat wider spread between L1 and L5, so in theory,
you could do better ionospheric corrections.

L1 - 1575.42

L2c - 1227.6

L5 - 1176.45

John, thanks

Could you elaborate a bit on these points:

-- L1/L5 bands only (no L2 option)
I read the amount of satellites transmitting L5 is a bit lower compared to
L2, are there other reasons why L2 is important? I guess one would have to
choose between L2 or L5 anyway in configuring a F9T, anything else?

-- only one TIMEPULSE output (could be a very big deal)
I failed to understand why this may be a big deal, can you explain?

Erik.

On 6/21/23 13:11, Erik Kaashoek via time-nuts wrote:

In the future, L5 will be a solid choice for the second frequency, and
it's fine now if you want only real-time results.  But the NRCan
post-processing service currently does not use L5 in its corrections so
you won't be able to upload RINEX files to get back precise location
information or clock offsets.  At some point, I'm sure they will process
L5 but that's not the case yet.  (Last time I checked they ignored L5
data included in an L1/L2/L5 RINEX, and I haven't been able to find
anything on the web indicating that they've started.)

One of the neat things about the prior u-blox timing receivers (and some
of the non-timing ones as well) is that they have two independent
timepulse outputs that can be programmed to RF frequencies (as high as
25 MHz for some).  You can use one output for PPS, and the other to
generate an RF signal that can be used, with appropriate cleanup as the
phase noise/jitter is horrible, as a frequency reference.  There are a
couple of modern GPSDO designs that take advantage of this, using the
second TP output to drive a Silicon Labs jitter attenuator/synthesizer chip.

Without the second TP signal, you can do PPS or RF but not both.

John

Hi

The “big deal” with no L2 is fairly simple:

One of the great things about dual freq modules is the ability to send off data
and very quickly get back a corrected version. If you use NRCan, this includes
clock corrections. They are good to the ~ 0.1 ns level. You can get to < 1x10^-14
in less than a day.

The problem is, the free correction services (at the moment) are L1 / L2 based.
For whatever reason, they don’t (yet) understand L5. That may change, or it
may not change. Right now, it’s the way it is ….

If you want to go crazy, the Mosaic-T is the best of the best in terms of GNSS
modules at the moment. They apparently are well aware of this and charge
accordingly. You can buy a lot of F9T’s for the price of one Mosaic-T.

Bob

On 6/21/23 10:11 AM, Erik Kaashoek via time-nuts wrote:

Today, there are fewer L5 than L2, but that's rapidly changing. And L5
gives you better performance, so you get a better result with fewer
satellites being tracked.