Need 10 MHz for DSN space-probe hunting
Hello, Time-Nutters--
Full disclosure-- I am a complete newbie at understanding the
intricacies of generating a really stable, low phase noise, accurate
frequency reference for microwave reception up around the 8 GHz
DSN (Deep Space Network) band. I have been following the back
and forth comments on the Time-Nuts list about improving the
Trimble T-bolt's 10 MHz output but confess that most of it is pretty
much deeper technical voo-doo than I am comfortable with.
I have been following the exploits of a group of folks around the
world who receive the incredibly weak signals from space probes
such as Juno. The idea is to detect the signals and then deduce
and confirm what probe is being detected by analyzing its doppler
and orbital characteristics.
This is being done at around 8.4 GHz with relatively small dishes of
under 8-ft diameter. Part of the magic that permits identifying
signals so far below the noise floor is the ability to use very narrow
bandwidth; as little as couple of Hz or even more narrow than that.
In order to do this a really accurate/stable/low phase-noise frequency
reference is needed.
I have been running a Trimble T-bolt 24/7/365 on Lady Heather
for around 5 years but have just started to take note of comments
on this list that the T-bolt is not really very good as a source to
phase-lock to for producing super narrow bandwidths of only one
or two Hz at 8 GHz. The comments I hear on the DSN space-probe
hunters chat-list is that obtaining a really high quality freq reference
is one of the big obstacles to success at this game.
My workbench test gear is limited to a pair of spectrum analyzers
(Tek 495AP and a Tek 494AP) and an HP 8714ES Vector Network Analyzer.
John Miles was the source for the Tek 495 spec-analyzer a few years ago.
John-- you might recall the check I sent you for the Tek495AP that
got lost...? Did it ever turn up?
Accordingly, what possible options might I have open to obtaining
a decent 10 MHz frequency reference for working up at the 8 GHz
DSN band? Any feedback on this will be much appreciated!
Mike Baker
Gainesville FL
(Micanopy, actually, about 12 miles south of Gainesville)
As a side note, I built a tracking downlink to receive and display
the digital imagery from the environmental low-earth polar orbit
satellites several years ago. This HRPT data comes down at around
1.7 GHz. The USA, Russia, Japan and China each have 2 to 4 of these
low-earth orbit birds (100 minute orbits) and one of them passes
overhead every other hour or so. I have a lot of trees around my
house and these limit my open-sky area but I can still start to get
solid reception when the birds pass over Cuba and drop-off when
they are over Tennessee.
Photos of my home-brew tracking station can be seen here in the
back yard behind my workshop building:
And some low-res screen-grabs of false-color infrared earth surface
images here:
Hello, Time-Nutters--
Full disclosure-- I am a complete newbie at understanding the
intricacies of generating a really stable, low phase noise, accurate
frequency reference for microwave reception up around the 8 GHz
DSN (Deep Space Network) band. I have been following the back
and forth comments on the Time-Nuts list about improving the
Trimble T-bolt's 10 MHz output but confess that most of it is pretty
much deeper technical voo-doo than I am comfortable with.
[]
Accordingly, what possible options might I have open to obtaining
a decent 10 MHz frequency reference for working up at the 8 GHz
DSN band? Any feedback on this will be much appreciated!
Mike Baker
Gainesville FL
(Micanopy, actually, about 12 miles south of Gainesville)
Briefly, Mike, there's an easy to use unit here, which takes a puck GPS antenna
and can run off USB +5V:
http://www.leobodnar.com/shop/index.php?main_page=product_info&products_id=234
Perhaps it might meet your needs?
Cheers,
David
On 9/13/16 10:04 AM, Mike Baker wrote:
Hello, Time-Nutters--
Full disclosure-- I am a complete newbie at understanding the
intricacies of generating a really stable, low phase noise, accurate
frequency reference for microwave reception up around the 8 GHz
DSN (Deep Space Network) band. I have been following the back
and forth comments on the Time-Nuts list about improving the
Trimble T-bolt's 10 MHz output but confess that most of it is pretty
much deeper technical voo-doo than I am comfortable with.
I have been following the exploits of a group of folks around the
world who receive the incredibly weak signals from space probes
such as Juno. The idea is to detect the signals and then deduce
and confirm what probe is being detected by analyzing its doppler
and orbital characteristics.
Accordingly, what possible options might I have open to obtaining
a decent 10 MHz frequency reference for working up at the 8 GHz
DSN band? Any feedback on this will be much appreciated!
I think that any sort of OCXO will do... your tbolt is probably "quiet
enough".
It's phase noise in the 1-100 Hz kind of area that you want to think
about, your LO multiply chain will increase the noise floor by
20*log10(N) going from 10 to 8450. (about 60dB)
The carrier you're looking for is very narrow band.. you can look at the
data sheet for a SDST (on General Dynamics website) and get the phase
noise of the AuxOsc, which will be the worst case noise. If they're
doing 2 way turnaround, the noise is better.
That sounds like fun!
Do they have a mailing list they hang out on?
https://eyes.nasa.gov/dsn/dsn.html
On 14/09/2016, at 5:04 AM, Mike Baker wrote:
Hello, Time-Nutters--
Full disclosure-- I am a complete newbie at understanding the
intricacies of generating a really stable, low phase noise, accurate
frequency reference for microwave reception up around the 8 GHz
DSN (Deep Space Network) band. I have been following the back
and forth comments on the Time-Nuts list about improving the
Trimble T-bolt's 10 MHz output but confess that most of it is pretty
much deeper technical voo-doo than I am comfortable with.
Just shipped out three new systems for $DAY_JOB to Goldstone, Madrid and Canberra.
Love it when work and time nuts intersect.
On Sep 13, 2016, at 17:35, Andy ZL3AG zl3ag@radioengineering.com wrote:
That sounds like fun!
Do they have a mailing list they hang out on?
On 14/09/2016, at 5:04 AM, Mike Baker wrote:
Hello, Time-Nutters--
Full disclosure-- I am a complete newbie at understanding the
intricacies of generating a really stable, low phase noise, accurate
frequency reference for microwave reception up around the 8 GHz
DSN (Deep Space Network) band. I have been following the back
and forth comments on the Time-Nuts list about improving the
Trimble T-bolt's 10 MHz output but confess that most of it is pretty
much deeper technical voo-doo than I am comfortable with.
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
On 9/13/16 2:35 PM, Andy ZL3AG wrote:
That sounds like fun!
Do they have a mailing list they hang out on?
yes.. amateur-dsn
https://groups.yahoo.com/neo/groups/amateur-DSN/info
https://eyes.nasa.gov/dsn/dsn.html
On 14/09/2016, at 5:04 AM, Mike Baker wrote:
Hello, Time-Nutters--
Full disclosure-- I am a complete newbie at understanding the
intricacies of generating a really stable, low phase noise, accurate
frequency reference for microwave reception up around the 8 GHz
DSN (Deep Space Network) band. I have been following the back
and forth comments on the Time-Nuts list about improving the
Trimble T-bolt's 10 MHz output but confess that most of it is pretty
much deeper technical voo-doo than I am comfortable with.
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
Hi
A more significant issue with the output of the TBolt for direct microwave multiplication
is the spurs on the output. When multiplied up to > 1 GHz, these are going to be a major
issue. There are a lot of conventional techniques for taking care of this. If you have not
already employed them, they are probably the first thing to take a look at.
For cross correlating signals, the time sync of the signals is at least as important as the
frequency error. As with phase noise, there are a lot of ways to address this. Most of the
“better frequency” suggestions here are also “worse time” suggestions.
Bob
On Sep 13, 2016, at 1:04 PM, Mike Baker mpb45@clanbaker.org wrote:
Hello, Time-Nutters--
Full disclosure-- I am a complete newbie at understanding the
intricacies of generating a really stable, low phase noise, accurate
frequency reference for microwave reception up around the 8 GHz
DSN (Deep Space Network) band. I have been following the back
and forth comments on the Time-Nuts list about improving the
Trimble T-bolt's 10 MHz output but confess that most of it is pretty
much deeper technical voo-doo than I am comfortable with.
I have been following the exploits of a group of folks around the
world who receive the incredibly weak signals from space probes
such as Juno. The idea is to detect the signals and then deduce
and confirm what probe is being detected by analyzing its doppler
and orbital characteristics.
This is being done at around 8.4 GHz with relatively small dishes of
under 8-ft diameter. Part of the magic that permits identifying
signals so far below the noise floor is the ability to use very narrow
bandwidth; as little as couple of Hz or even more narrow than that.
In order to do this a really accurate/stable/low phase-noise frequency
reference is needed.
I have been running a Trimble T-bolt 24/7/365 on Lady Heather
for around 5 years but have just started to take note of comments
on this list that the T-bolt is not really very good as a source to
phase-lock to for producing super narrow bandwidths of only one
or two Hz at 8 GHz. The comments I hear on the DSN space-probe
hunters chat-list is that obtaining a really high quality freq reference
is one of the big obstacles to success at this game.
My workbench test gear is limited to a pair of spectrum analyzers
(Tek 495AP and a Tek 494AP) and an HP 8714ES Vector Network Analyzer.
John Miles was the source for the Tek 495 spec-analyzer a few years ago.
John-- you might recall the check I sent you for the Tek495AP that
got lost...? Did it ever turn up?
Accordingly, what possible options might I have open to obtaining
a decent 10 MHz frequency reference for working up at the 8 GHz
DSN band? Any feedback on this will be much appreciated!
Mike Baker
Gainesville FL
(Micanopy, actually, about 12 miles south of Gainesville)
As a side note, I built a tracking downlink to receive and display
the digital imagery from the environmental low-earth polar orbit
satellites several years ago. This HRPT data comes down at around
1.7 GHz. The USA, Russia, Japan and China each have 2 to 4 of these
low-earth orbit birds (100 minute orbits) and one of them passes
overhead every other hour or so. I have a lot of trees around my
house and these limit my open-sky area but I can still start to get
solid reception when the birds pass over Cuba and drop-off when
they are over Tennessee.
Photos of my home-brew tracking station can be seen here in the
back yard behind my workshop building:
And some low-res screen-grabs of false-color infrared earth surface
images here:
time-nuts mailing list -- time-nuts@febo.com
To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
and follow the instructions there.
Briefly, Mike, there's an easy to use unit here, which takes a puck GPS antenna and can run off USB +5V:
http://www.leobodnar.com/shop/index.php?main_page=product_info&products_id=234
Perhaps it might meet your needs?
Cheers,
David
Just wanted to add, their US distributor has one with a custom xtal that claims even lower phase noise and has provided a plot comparing the two:
http://www.force12inc.com/products/gps-locked-precision-frequency-reference-low-jitter-gps-clock-450-hz-to-800-mhz-output-custom-low-phase-noise-xtal-version.html
Just wanted to add, their US distributor has one with a custom xtal that claims even lower phase noise and has provided a plot comparing the two
I see the US distributor says the "custom" unit's phase noise
"improv[es] on an already impressive figure" of the stock unit. But in
reality, even the custom unit doesn't have an "impressive" PN figure --
the phase noise is still at least 10dB worse than a real GPSDO. It
appears that the outputs are generated by a DDS or similar, so that is
not surprising. Good for frequency agility, lousy for frequency
stability and spurious outputs.
This thing has its place in the world of clocks, but it is not a
precision GPSDO. It is not even in the league of a number of hobbyist
and DIY designs. I wish people would stop recommending it to people
whose application calls for a real GPSDO (such as multiplying up to the
GHz region).
Best regards,
Charles