Re: [time-nuts] Need help in test board pinout for SA22.c oscillator - thanks in advance

[Andrew Rodland]

I remember when I started experimenting with Rb and I thought "why
would I want to give it more cooling? That's just more contact with
the outside world, and more chance for the room temperature variation
to throw things off. I'll just put it on the desk, it'll be more
stable that way."

And then someone finally got through to me: the Rb has a heater to
regulate the temperature, but the heater can only regulate temperature
*up*, not *down*. If you have enough cooling to remove the operating
heat output plus some fraction of the heater's output, at the
specified case temperature and your range of room temperatures, then
the heater will operate some fraction of the time and the physics
package temperature will be well-regulated. With less cooling than
that, the temperature becomes effectively unregulated, because if the
unit is too hot, the heater can't help.

Of course, lots of thermal mass in the heatsink helps too if you want
to damp out the effects of air-conditioner cycling and the like.

On Thu, Nov 7, 2019 at 8:18 PM Bob kb8tq  wrote:
>
> Hi
>
> You probably need more heat sinking than that assembly provides. It’s a case 
> of “better to much
> than to little”. The life of the device will extended with more heat sinking.
>
> Bob
>
> > On Nov 7, 2019, at 2:47 PM, Fio Cattaneo (.US)  wrote:
> >
> > Hello folks, I just got a Symmetricom SA22.C oscillator on Ebay. The
> > oscillator comes mounted on a test board which seems to drastically reduce
> > the number of pins (I’m guessing it consolidates all the GND and VDD pins
> > in one) and potentially obviating the need of providing both +15V and +5V
> > (looks like there is a voltage regulator).
> >
> >
> >
> > However, I do not recognize the board (it’s definitely not the one shown in
> > the SA22.C user manual), so I’m asking here…… Thanks much in advance !
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> >
> > --- Fio Cattaneo
> >
> >
> >
> > Universal AC, can Entropy be reversed? -- "THERE IS AS YET INSUFFICIENT
> > DATA FOR A MEANINGFUL ANSWER."
> > ___
> > time-nuts mailing list -- time-nuts@lists.febo.com
> > To unsubscribe, go to 
> > http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
> > and follow the instructions there.
>
>
> ___
> time-nuts mailing list -- time-nuts@lists.febo.com
> To unsubscribe, go to 
> http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
> and follow the instructions there.

___
time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe, go to 
http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
and follow the instructions there.

Re: [time-nuts] Difference in antennas

[Bob kb8tq]

Hi

If you have a survey device like a Trimble NetRS then you *must* have a high 
gain antenna.
If you want to feed it from the Trimble, you need an antenna that runs on 12V. 
It also needs to
be an L1 / L2 antenna. 

If all you have a TBolt timing receiver, then you want a 20 db gain antenna 
that runs on 5V and
that is an L1 only device. 

If you have some of each, then a 50 db antenna fed off of the NetRS / split / 
padded down to feed
the TBolt is your best bet.

Noise figure it what matters. The preamp in the antenna either does or does not 
have enough gain
to set the noise figure for the system. As long as it can do that job reception 
will not improve with
added gain. 

If you are installing a system in a cell site, then the signals from the tower 
are going to be an issue
into your GPS antenna. Even wandering around the house, your cell phone may / 
can / might 
be an issue. It all depends on how far the cell tower is, just where you are 
standing, and how far
away the GPS antenna is ….

Bob

> On Nov 21, 2019, at 4:09 PM, Taka Kamiya via time-nuts 
>  wrote:
> 
> So concensus is, 50dB gain antenna is too much gain, unless feed line is 
> too long, reception is poor, or there are other circumstances extra gain is 
> desired?
> 
> --- 
> (Mr.) Taka Kamiya
> KB4EMF / ex JF2DKG
> 
> 
>On Thursday, November 21, 2019, 3:00:14 PM EST, Bob kb8tq  
> wrote:  
> 
> Hi
> 
> That is indeed the gotcha. Once you get past a certain amount of gain in the
> preamp, the C/N levels don’t change enough to notice. Looking today vs looking
> tomorrow is unlikely to be of any help if you are after a fraction of a db. 
> 
> About the only way to check would be to fast switch an attenuator in and out 
> of
> the signal path. Watch things for a minute at one setting and then do the 
> same at
> another setting. Run for a while and log all the deltas. If you see a 
> degradation of
> more than a few tenths of a db, you are getting towards the minimum gain 
> point. 
> 
> Indeed there are some receivers that have an AGC built in. *IF* your receiver 
> has one
> and *IF* you can get at it, that would be a great way to work this out. 
> Indeed anybody
> who makes it past both of those constraints has a pretty unique device.
> 
> 
> 
> Simple answer for a 50 db antenna is to put an attenuator in after the DC has
> been eliminated from the circuit. It’s not idea, but it’s the best you can 
> do. Running
> a great big splitter is one great way to come up with attenuation …..
> 
> Bob
> 
> 
>> On Nov 21, 2019, at 10:29 AM, John Ackermann N8UR  wrote:
>> 
>> Bob, this is a great summary, thanks!
>> 
>> One related question, especially with mixed systems -- how do you tell
>> if you have optimum signal level at the receiver?
>> 
>> Most show some sort of SNR or Cn value.  What should we look for?  What
>> are the indication of *too much* signal?  One issue in particular is how
>> to handle a modern GPS that expects modest antenna gain when it's
>> plugged into a system with a 50dB gain antenna at the top.
>> 
>> Thanks!
>> John
>> 
>> 
>> On 11/21/19 8:00 AM, Bob kb8tq wrote:
>>> Hi
>>> 
>>> Way back in time, the first gear out there to use what we now look at as 
>>> “normal” antennas 
>>> was survey gear. For various reasons they decided on a 12V power supply and 
>>> 40 to 50 db
>>> of gain in the preamp mounted in the antenna. They also got into L1 / L2 
>>> pretty quickly. 
>>> 
>>> A bit later the cell phone (and later broadcast) guys got into this. In a 
>>> location with a lot of 
>>> RF (like a cell site) having a lot of gain at the antenna didn’t work all 
>>> that well. IMD issues 
>>> got into the act pretty quickly. In addition, front end filtering was 
>>> required to reduce overload
>>> issues. The focus was on L1 only so filtering was relatively easy.
>>> 
>>> There is a whole separate set of antennas that put a big chunk of the RF 
>>> portion of the radio
>>> in the antenna. Those still survive here and there. I have one of them and 
>>> probably a couple
>>> of dozen of the more “normal” antennas. 
>>> 
>>> As time marched on, supplying 12V to antennas became a bit less popular. 
>>> Most of the cell 
>>> guys went over to a 5V antenna supply. The net result was 12V 50 db survey 
>>> antennas that did 
>>> L1/L2 and much smaller 5V 25 db antennas for “timing”. The timing antennas 
>>> didn’t do L1/L2 so
>>> not going to work for survey. The survey antennas had way to much gain and 
>>> no filtering so 
>>> not going to work for a cell site. 
>>> 
>>> Indeed things did and do get crossed up in various pro and basement 
>>> systems. With care and
>>> the right set of circumstances things may work. In other cases the result 
>>> can be an ongoing set
>>> of systems issues over an entire network of stations. 
>>> 
>>> Prices for a good new survey antenna are up in the many thousands of 
>>> dollars range. They have
>>> very stable phase centers and (usually) test re

Re: [time-nuts] Difference in antennas

[Dana Whitlow]

Most modern GPS receivers are very quiet even barefoot.  So, one could
argue that one should
not have much more LNA gain in the antenna than required to make up for
feedline loss, which
should be easily calculable.  While excess gain  in the antenna can improve
overall system noise
figure a small amount, it will degrade intermod performance, which is
likely to be a worse problem
than simple weak signals.  It's likely that the cure is worse than the
disease, as my doctor likes to
say.

Dana



On Thu, Nov 21, 2019 at 4:00 PM Taka Kamiya via time-nuts <
time-nuts@lists.febo.com> wrote:

> So concensus is, 50dB gain antenna is too much gain, unless feed line
> is too long, reception is poor, or there are other circumstances extra gain
> is desired?
>
> ---
> (Mr.) Taka Kamiya
> KB4EMF / ex JF2DKG
>
>
> On Thursday, November 21, 2019, 3:00:14 PM EST, Bob kb8tq <
> kb...@n1k.org> wrote:
>
>  Hi
>
> That is indeed the gotcha. Once you get past a certain amount of gain in
> the
> preamp, the C/N levels don’t change enough to notice. Looking today vs
> looking
> tomorrow is unlikely to be of any help if you are after a fraction of a
> db.
>
> About the only way to check would be to fast switch an attenuator in and
> out of
> the signal path. Watch things for a minute at one setting and then do the
> same at
> another setting. Run for a while and log all the deltas. If you see a
> degradation of
> more than a few tenths of a db, you are getting towards the minimum gain
> point.
>
> Indeed there are some receivers that have an AGC built in. *IF* your
> receiver has one
> and *IF* you can get at it, that would be a great way to work this out.
> Indeed anybody
> who makes it past both of those constraints has a pretty unique device.
>
> 
>
> Simple answer for a 50 db antenna is to put an attenuator in after the DC
> has
> been eliminated from the circuit. It’s not idea, but it’s the best you can
> do. Running
> a great big splitter is one great way to come up with attenuation …..
>
> Bob
>
>
> > On Nov 21, 2019, at 10:29 AM, John Ackermann N8UR  wrote:
> >
> > Bob, this is a great summary, thanks!
> >
> > One related question, especially with mixed systems -- how do you tell
> > if you have optimum signal level at the receiver?
> >
> > Most show some sort of SNR or Cn value.  What should we look for?  What
> > are the indication of *too much* signal?  One issue in particular is how
> > to handle a modern GPS that expects modest antenna gain when it's
> > plugged into a system with a 50dB gain antenna at the top.
> >
> > Thanks!
> > John
> > 
> >
> > On 11/21/19 8:00 AM, Bob kb8tq wrote:
> >> Hi
> >>
> >> Way back in time, the first gear out there to use what we now look at
> as “normal” antennas
> >> was survey gear. For various reasons they decided on a 12V power supply
> and 40 to 50 db
> >> of gain in the preamp mounted in the antenna. They also got into L1 /
> L2 pretty quickly.
> >>
> >> A bit later the cell phone (and later broadcast) guys got into this. In
> a location with a lot of
> >> RF (like a cell site) having a lot of gain at the antenna didn’t work
> all that well. IMD issues
> >> got into the act pretty quickly. In addition, front end filtering was
> required to reduce overload
> >> issues. The focus was on L1 only so filtering was relatively easy.
> >>
> >> There is a whole separate set of antennas that put a big chunk of the
> RF portion of the radio
> >> in the antenna. Those still survive here and there. I have one of them
> and probably a couple
> >> of dozen of the more “normal” antennas.
> >>
> >> As time marched on, supplying 12V to antennas became a bit less
> popular. Most of the cell
> >> guys went over to a 5V antenna supply. The net result was 12V 50 db
> survey antennas that did
> >> L1/L2 and much smaller 5V 25 db antennas for “timing”. The timing
> antennas didn’t do L1/L2 so
> >> not going to work for survey. The survey antennas had way to much gain
> and no filtering so
> >> not going to work for a cell site.
> >>
> >> Indeed things did and do get crossed up in various pro and basement
> systems. With care and
> >> the right set of circumstances things may work. In other cases the
> result can be an ongoing set
> >> of systems issues over an entire network of stations.
> >>
> >> Prices for a good new survey antenna are up in the many thousands of
> dollars range. They have
> >> very stable phase centers and (usually) test results to allow
> correction of any residual phase
> >> issues. This is part of what lets you get into the “couple of mm” range
> on a survey.
> >>
> >> For timing, you have to dig a bit and answer a few questions. Is your
> concern how close you
> >> are to BIH? If so you will need to know all the delays in your system.
> This includes the delays
> >> in the antenna filters and the preamp. Is your concern (or measure) the
> ADEV at 1 second?
> >> If so the delays are not a concern. Your antenna choice may be a bit

Re: [time-nuts] Difference in antennas

[Taka Kamiya via time-nuts]

So concensus is, 50dB gain antenna is too much gain, unless feed line is 
too long, reception is poor, or there are other circumstances extra gain is 
desired?

--- 
(Mr.) Taka Kamiya
KB4EMF / ex JF2DKG
 

On Thursday, November 21, 2019, 3:00:14 PM EST, Bob kb8tq  
wrote:  
 
 Hi

That is indeed the gotcha. Once you get past a certain amount of gain in the
preamp, the C/N levels don’t change enough to notice. Looking today vs looking
tomorrow is unlikely to be of any help if you are after a fraction of a db. 

About the only way to check would be to fast switch an attenuator in and out of
the signal path. Watch things for a minute at one setting and then do the same 
at
another setting. Run for a while and log all the deltas. If you see a 
degradation of
more than a few tenths of a db, you are getting towards the minimum gain point. 

Indeed there are some receivers that have an AGC built in. *IF* your receiver 
has one
and *IF* you can get at it, that would be a great way to work this out. Indeed 
anybody
who makes it past both of those constraints has a pretty unique device.



Simple answer for a 50 db antenna is to put an attenuator in after the DC has
been eliminated from the circuit. It’s not idea, but it’s the best you can do. 
Running
a great big splitter is one great way to come up with attenuation …..

Bob


> On Nov 21, 2019, at 10:29 AM, John Ackermann N8UR  wrote:
> 
> Bob, this is a great summary, thanks!
> 
> One related question, especially with mixed systems -- how do you tell
> if you have optimum signal level at the receiver?
> 
> Most show some sort of SNR or Cn value.  What should we look for?  What
> are the indication of *too much* signal?  One issue in particular is how
> to handle a modern GPS that expects modest antenna gain when it's
> plugged into a system with a 50dB gain antenna at the top.
> 
> Thanks!
> John
> 
> 
> On 11/21/19 8:00 AM, Bob kb8tq wrote:
>> Hi
>> 
>> Way back in time, the first gear out there to use what we now look at as 
>> “normal” antennas 
>> was survey gear. For various reasons they decided on a 12V power supply and 
>> 40 to 50 db
>> of gain in the preamp mounted in the antenna. They also got into L1 / L2 
>> pretty quickly. 
>> 
>> A bit later the cell phone (and later broadcast) guys got into this. In a 
>> location with a lot of 
>> RF (like a cell site) having a lot of gain at the antenna didn’t work all 
>> that well. IMD issues 
>> got into the act pretty quickly. In addition, front end filtering was 
>> required to reduce overload
>> issues. The focus was on L1 only so filtering was relatively easy.
>> 
>> There is a whole separate set of antennas that put a big chunk of the RF 
>> portion of the radio
>> in the antenna. Those still survive here and there. I have one of them and 
>> probably a couple
>> of dozen of the more “normal” antennas. 
>> 
>> As time marched on, supplying 12V to antennas became a bit less popular. 
>> Most of the cell 
>> guys went over to a 5V antenna supply. The net result was 12V 50 db survey 
>> antennas that did 
>> L1/L2 and much smaller 5V 25 db antennas for “timing”. The timing antennas 
>> didn’t do L1/L2 so
>> not going to work for survey. The survey antennas had way to much gain and 
>> no filtering so 
>> not going to work for a cell site. 
>> 
>> Indeed things did and do get crossed up in various pro and basement systems. 
>> With care and
>> the right set of circumstances things may work. In other cases the result 
>> can be an ongoing set
>> of systems issues over an entire network of stations. 
>> 
>> Prices for a good new survey antenna are up in the many thousands of dollars 
>> range. They have
>> very stable phase centers and (usually) test results to allow correction of 
>> any residual phase 
>> issues. This is part of what lets you get into the “couple of mm” range on a 
>> survey. 
>> 
>> For timing, you have to dig a bit and answer a few questions. Is your 
>> concern how close you
>> are to BIH? If so you will need to know all the delays in your system. This 
>> includes the delays
>> in the antenna filters and the preamp. Is your concern (or measure) the ADEV 
>> at 1 second?
>> If so the delays are not a concern. Your antenna choice may be a bit 
>> different depending on
>> this focus.
>> 
>> Bob
>> 
>> 
>> 
>>> On Nov 21, 2019, at 1:25 AM, Taka Kamiya via time-nuts 
>>>  wrote:
>>> 
>>> I have been looking antennas.  Prices seem to range less than 30 dollars to 
>>> more than 500 dollars.  Some are 20db gain and some are 40 db gain.  Some 
>>> are specified as marine use only.  Some are specified as timing use.  Some 
>>> doesn't say anything at all.  Power supplies are different.
>>> Other than obvious, antenna is an antenna, isn't it?  It captures L1 
>>> signal, amplify it and send it down the coax.  What makes one more costly 
>>> than others?  What makes one timing antenna and one navigation antenna?  It 
>>> doesn't make sense to me. 

Re: [time-nuts] tracking position & orientation

[Bob kb8tq]

Hi

The “cheap” approach these days is to use a uBlox ZED-F9P 

https://www.digikey.com/products/en/rf-if-and-rfid/rf-evaluation-and-development-kits-boards/859?k=F9P
 


along with one (or more) the <$100 eBay antennas. You take 24 hour data 
runs and ship them off to any of several free analysis outfits. One is NRCan.
There are a lot of others. They all do a fine job.

Bob



> On Nov 21, 2019, at 3:13 PM, Eric Scace  wrote:
> 
>   I need another project like a hole in the head — but curiosity continues to 
> nag me.
> 
>   I moved to Boulder CO a few months ago. The “curiosity” is to determine the 
> position of two antennas at either end of my house and monitor it over time, 
> with the idea that one could see plate movement in 3 dimensions plus rotation 
> around the axes.
> 
>   What hardware/software would be suitable for a TimeNuts (PositionNuts?) 
> project like this?
> 
> — Eric K3NA
> 
> 
>> On 11/21/19 8:00 AM, Bob kb8tq wrote:
>> Hi
>> 
>> Way back in time, the first gear out there to use what we now look at as 
>> “normal” antennas 
>> was survey gear. For various reasons they decided on a 12V power supply and 
>> 40 to 50 db
>> of gain in the preamp mounted in the antenna. They also got into L1 / L2 
>> pretty quickly. 
>> 
>> A bit later the cell phone (and later broadcast) guys got into this. In a 
>> location with a lot of 
>> RF (like a cell site) having a lot of gain at the antenna didn’t work all 
>> that well. IMD issues 
>> got into the act pretty quickly. In addition, front end filtering was 
>> required to reduce overload
>> issues. The focus was on L1 only so filtering was relatively easy.
>> 
>> There is a whole separate set of antennas that put a big chunk of the RF 
>> portion of the radio
>> in the antenna. Those still survive here and there. I have one of them and 
>> probably a couple
>> of dozen of the more “normal” antennas. 
>> 
>> As time marched on, supplying 12V to antennas became a bit less popular. 
>> Most of the cell 
>> guys went over to a 5V antenna supply. The net result was 12V 50 db survey 
>> antennas that did 
>> L1/L2 and much smaller 5V 25 db antennas for “timing”. The timing antennas 
>> didn’t do L1/L2 so
>> not going to work for survey. The survey antennas had way to much gain and 
>> no filtering so 
>> not going to work for a cell site. 
>> 
>> Indeed things did and do get crossed up in various pro and basement systems. 
>> With care and
>> the right set of circumstances things may work. In other cases the result 
>> can be an ongoing set
>> of systems issues over an entire network of stations. 
>> 
>> Prices for a good new survey antenna are up in the many thousands of dollars 
>> range. They have
>> very stable phase centers and (usually) test results to allow correction of 
>> any residual phase 
>> issues. This is part of what lets you get into the “couple of mm” range on a 
>> survey. 
>> 
>> For timing, you have to dig a bit and answer a few questions. Is your 
>> concern how close you
>> are to BIH? If so you will need to know all the delays in your system. This 
>> includes the delays
>> in the antenna filters and the preamp. Is your concern (or measure) the ADEV 
>> at 1 second?
>> If so the delays are not a concern. Your antenna choice may be a bit 
>> different depending on
>> this focus.
>> 
>> Bob
> 
> ___
> time-nuts mailing list -- time-nuts@lists.febo.com
> To unsubscribe, go to 
> http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
> and follow the instructions there.

___
time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe, go to 
http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
and follow the instructions there.

Re: [time-nuts] Difference in antennas

[Greg Troxel]

John Ackermann N8UR  writes:

> One related question, especially with mixed systems -- how do you tell
> if you have optimum signal level at the receiver?
>
> Most show some sort of SNR or Cn value.  What should we look for?  What
> are the indication of *too much* signal?  One issue in particular is how
> to handle a modern GPS that expects modest antenna gain when it's
> plugged into a system with a 50dB gain antenna at the top.

Too much gain can manifest in at least two different ways:

  1) intermodulation distortion in the preamp

  2) distortion/overload in the GPS receiver

Adding an attenuator or cable as someone suggested can help you
determine if the preamp gain is excessive *given your cabling and GPSr
frontend*.  If you add 10 dB of loss, and the C/N0 doesn't change,
arguably you have gain you didn't need, and which therefore has elevated
risk of IMD.  If it goes up, you (mostly) know you are overdriving your
receiver (which would be surprising to me).  If it drops, then you
probably need most of the gain.

This is tricky, because a system with too much preamp gain will be prone
to IMD if other signals appear but may operate just fine when they
don't.

That said, I am unclear on:

  typical filtering before the antenna preamp (very little in a
  dual-frequency antenna?)

  3rd-order IMD dynamic range in these preamps

  strength of non-GNSS signals that appear in the filter passband


___
time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe, go to 
http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
and follow the instructions there.

[time-nuts] tracking position & orientation

[Eric Scace]

   I need another project like a hole in the head — but curiosity continues to 
nag me.

   I moved to Boulder CO a few months ago. The “curiosity” is to determine the 
position of two antennas at either end of my house and monitor it over time, 
with the idea that one could see plate movement in 3 dimensions plus rotation 
around the axes.

   What hardware/software would be suitable for a TimeNuts (PositionNuts?) 
project like this?

— Eric K3NA


> On 11/21/19 8:00 AM, Bob kb8tq wrote:
> Hi
> 
> Way back in time, the first gear out there to use what we now look at as 
> “normal” antennas 
> was survey gear. For various reasons they decided on a 12V power supply and 
> 40 to 50 db
> of gain in the preamp mounted in the antenna. They also got into L1 / L2 
> pretty quickly. 
> 
> A bit later the cell phone (and later broadcast) guys got into this. In a 
> location with a lot of 
> RF (like a cell site) having a lot of gain at the antenna didn’t work all 
> that well. IMD issues 
> got into the act pretty quickly. In addition, front end filtering was 
> required to reduce overload
> issues. The focus was on L1 only so filtering was relatively easy.
> 
> There is a whole separate set of antennas that put a big chunk of the RF 
> portion of the radio
> in the antenna. Those still survive here and there. I have one of them and 
> probably a couple
> of dozen of the more “normal” antennas. 
> 
> As time marched on, supplying 12V to antennas became a bit less popular. Most 
> of the cell 
> guys went over to a 5V antenna supply. The net result was 12V 50 db survey 
> antennas that did 
> L1/L2 and much smaller 5V 25 db antennas for “timing”. The timing antennas 
> didn’t do L1/L2 so
> not going to work for survey. The survey antennas had way to much gain and no 
> filtering so 
> not going to work for a cell site. 
> 
> Indeed things did and do get crossed up in various pro and basement systems. 
> With care and
> the right set of circumstances things may work. In other cases the result can 
> be an ongoing set
> of systems issues over an entire network of stations. 
> 
> Prices for a good new survey antenna are up in the many thousands of dollars 
> range. They have
> very stable phase centers and (usually) test results to allow correction of 
> any residual phase 
> issues. This is part of what lets you get into the “couple of mm” range on a 
> survey. 
> 
> For timing, you have to dig a bit and answer a few questions. Is your concern 
> how close you
> are to BIH? If so you will need to know all the delays in your system. This 
> includes the delays
> in the antenna filters and the preamp. Is your concern (or measure) the ADEV 
> at 1 second?
> If so the delays are not a concern. Your antenna choice may be a bit 
> different depending on
> this focus.
> 
> Bob

___
time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe, go to 
http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
and follow the instructions there.

Re: [time-nuts] Difference in antennas

[Bob kb8tq]

Hi

That is indeed the gotcha. Once you get past a certain amount of gain in the
preamp, the C/N levels don’t change enough to notice. Looking today vs looking
tomorrow is unlikely to be of any help if you are after a fraction of a db. 

About the only way to check would be to fast switch an attenuator in and out of
the signal path. Watch things for a minute at one setting and then do the same 
at
another setting. Run for a while and log all the deltas. If you see a 
degradation of
more than a few tenths of a db, you are getting towards the minimum gain point. 

Indeed there are some receivers that have an AGC built in. *IF* your receiver 
has one
and *IF* you can get at it, that would be a great way to work this out. Indeed 
anybody
who makes it past both of those constraints has a pretty unique device.



Simple answer for a 50 db antenna is to put an attenuator in after the DC has
been eliminated from the circuit. It’s not idea, but it’s the best you can do. 
Running
a great big splitter is one great way to come up with attenuation …..

Bob


> On Nov 21, 2019, at 10:29 AM, John Ackermann N8UR  wrote:
> 
> Bob, this is a great summary, thanks!
> 
> One related question, especially with mixed systems -- how do you tell
> if you have optimum signal level at the receiver?
> 
> Most show some sort of SNR or Cn value.  What should we look for?  What
> are the indication of *too much* signal?  One issue in particular is how
> to handle a modern GPS that expects modest antenna gain when it's
> plugged into a system with a 50dB gain antenna at the top.
> 
> Thanks!
> John
> 
> 
> On 11/21/19 8:00 AM, Bob kb8tq wrote:
>> Hi
>> 
>> Way back in time, the first gear out there to use what we now look at as 
>> “normal” antennas 
>> was survey gear. For various reasons they decided on a 12V power supply and 
>> 40 to 50 db
>> of gain in the preamp mounted in the antenna. They also got into L1 / L2 
>> pretty quickly. 
>> 
>> A bit later the cell phone (and later broadcast) guys got into this. In a 
>> location with a lot of 
>> RF (like a cell site) having a lot of gain at the antenna didn’t work all 
>> that well. IMD issues 
>> got into the act pretty quickly. In addition, front end filtering was 
>> required to reduce overload
>> issues. The focus was on L1 only so filtering was relatively easy.
>> 
>> There is a whole separate set of antennas that put a big chunk of the RF 
>> portion of the radio
>> in the antenna. Those still survive here and there. I have one of them and 
>> probably a couple
>> of dozen of the more “normal” antennas. 
>> 
>> As time marched on, supplying 12V to antennas became a bit less popular. 
>> Most of the cell 
>> guys went over to a 5V antenna supply. The net result was 12V 50 db survey 
>> antennas that did 
>> L1/L2 and much smaller 5V 25 db antennas for “timing”. The timing antennas 
>> didn’t do L1/L2 so
>> not going to work for survey. The survey antennas had way to much gain and 
>> no filtering so 
>> not going to work for a cell site. 
>> 
>> Indeed things did and do get crossed up in various pro and basement systems. 
>> With care and
>> the right set of circumstances things may work. In other cases the result 
>> can be an ongoing set
>> of systems issues over an entire network of stations. 
>> 
>> Prices for a good new survey antenna are up in the many thousands of dollars 
>> range. They have
>> very stable phase centers and (usually) test results to allow correction of 
>> any residual phase 
>> issues. This is part of what lets you get into the “couple of mm” range on a 
>> survey. 
>> 
>> For timing, you have to dig a bit and answer a few questions. Is your 
>> concern how close you
>> are to BIH? If so you will need to know all the delays in your system. This 
>> includes the delays
>> in the antenna filters and the preamp. Is your concern (or measure) the ADEV 
>> at 1 second?
>> If so the delays are not a concern. Your antenna choice may be a bit 
>> different depending on
>> this focus.
>> 
>> Bob
>> 
>> 
>> 
>>> On Nov 21, 2019, at 1:25 AM, Taka Kamiya via time-nuts 
>>>  wrote:
>>> 
>>> I have been looking antennas.  Prices seem to range less than 30 dollars to 
>>> more than 500 dollars.  Some are 20db gain and some are 40 db gain.  Some 
>>> are specified as marine use only.  Some are specified as timing use.  Some 
>>> doesn't say anything at all.  Power supplies are different.
>>> Other than obvious, antenna is an antenna, isn't it?  It captures L1 
>>> signal, amplify it and send it down the coax.  What makes one more costly 
>>> than others?  What makes one timing antenna and one navigation antenna?  It 
>>> doesn't make sense to me.  
>>> 
>>> I did some simple experiment with 26db, 40db, and magnetic stick on type.  
>>> I didn't really see significant difference.  Signal level itself even 
>>> wasn't all that different.  I have nearly a clear sky view 360 degrees 
>>> above 30 degrees above horizon.  In some directions, clear view to horizon. 
>>>

Re: [time-nuts] Difference in antennas

[Achim Gratz]

John Ackermann N8UR writes:
> One related question, especially with mixed systems -- how do you tell
> if you have optimum signal level at the receiver?

I don't think you're going to figure out an _optimum_ gain without
proper measurements along the whole signal chain.  As a proxy, the
reported SNR should stay fairly constant with changing constellation and
environmental conditions.

> Most show some sort of SNR or Cn value.  What should we look for?  What
> are the indication of *too much* signal?  One issue in particular is how
> to handle a modern GPS that expects modest antenna gain when it's
> plugged into a system with a 50dB gain antenna at the top.

That one is easy to solve with either a too long / too low quality
cable.  :-) Otherwise you may just have to add a 20..30dB damping plug
on the receiver side.  Keep in mind that a 50dB antenna typically either
would not work at all with the supply coming from that GPS module (12V
vs. 5V or even just 3.3V) or actually has lower gain because of the
lower supply voltage.  So you may need a DC block on the receiver and a
bias-Tee at the antenna as well.


Regards,
Achim.
-- 
+<[Q+ Matrix-12 WAVE#46+305 Neuron microQkb Andromeda XTk Blofeld]>+

Factory and User Sound Singles for Waldorf Blofeld:
http://Synth.Stromeko.net/Downloads.html#WaldorfSounds

___
time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe, go to 
http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
and follow the instructions there.

Re: [time-nuts] Difference in antennas

[John Ackermann N8UR]

Bob, this is a great summary, thanks!

One related question, especially with mixed systems -- how do you tell
if you have optimum signal level at the receiver?

Most show some sort of SNR or Cn value.  What should we look for?  What
are the indication of *too much* signal?  One issue in particular is how
to handle a modern GPS that expects modest antenna gain when it's
plugged into a system with a 50dB gain antenna at the top.

Thanks!
John


On 11/21/19 8:00 AM, Bob kb8tq wrote:
> Hi
> 
> Way back in time, the first gear out there to use what we now look at as 
> “normal” antennas 
> was survey gear. For various reasons they decided on a 12V power supply and 
> 40 to 50 db
> of gain in the preamp mounted in the antenna. They also got into L1 / L2 
> pretty quickly. 
> 
> A bit later the cell phone (and later broadcast) guys got into this. In a 
> location with a lot of 
> RF (like a cell site) having a lot of gain at the antenna didn’t work all 
> that well. IMD issues 
> got into the act pretty quickly. In addition, front end filtering was 
> required to reduce overload
> issues. The focus was on L1 only so filtering was relatively easy.
> 
> There is a whole separate set of antennas that put a big chunk of the RF 
> portion of the radio
> in the antenna. Those still survive here and there. I have one of them and 
> probably a couple
> of dozen of the more “normal” antennas. 
> 
> As time marched on, supplying 12V to antennas became a bit less popular. Most 
> of the cell 
> guys went over to a 5V antenna supply. The net result was 12V 50 db survey 
> antennas that did 
> L1/L2 and much smaller 5V 25 db antennas for “timing”. The timing antennas 
> didn’t do L1/L2 so
> not going to work for survey. The survey antennas had way to much gain and no 
> filtering so 
> not going to work for a cell site. 
> 
> Indeed things did and do get crossed up in various pro and basement systems. 
> With care and
> the right set of circumstances things may work. In other cases the result can 
> be an ongoing set
> of systems issues over an entire network of stations. 
> 
> Prices for a good new survey antenna are up in the many thousands of dollars 
> range. They have
> very stable phase centers and (usually) test results to allow correction of 
> any residual phase 
> issues. This is part of what lets you get into the “couple of mm” range on a 
> survey. 
> 
> For timing, you have to dig a bit and answer a few questions. Is your concern 
> how close you
> are to BIH? If so you will need to know all the delays in your system. This 
> includes the delays
> in the antenna filters and the preamp. Is your concern (or measure) the ADEV 
> at 1 second?
> If so the delays are not a concern. Your antenna choice may be a bit 
> different depending on
> this focus.
> 
> Bob
> 
> 
> 
>> On Nov 21, 2019, at 1:25 AM, Taka Kamiya via time-nuts 
>>  wrote:
>>
>> I have been looking antennas.  Prices seem to range less than 30 dollars to 
>> more than 500 dollars.  Some are 20db gain and some are 40 db gain.  Some 
>> are specified as marine use only.  Some are specified as timing use.  Some 
>> doesn't say anything at all.  Power supplies are different.
>> Other than obvious, antenna is an antenna, isn't it?  It captures L1 signal, 
>> amplify it and send it down the coax.  What makes one more costly than 
>> others?  What makes one timing antenna and one navigation antenna?  It 
>> doesn't make sense to me.  
>>
>> I did some simple experiment with 26db, 40db, and magnetic stick on type.  I 
>> didn't really see significant difference.  Signal level itself even wasn't 
>> all that different.  I have nearly a clear sky view 360 degrees above 30 
>> degrees above horizon.  In some directions, clear view to horizon.  My feed 
>> is Timewave type.  So It may not be the best but nearly ideal.  
>>
>> Can someone shed light on this topic?  (of course, I know some antenna has 
>> integrated receiver.  I am not talking about those)
>>
>> --- 
>> (Mr.) Taka Kamiya
>> KB4EMF / ex JF2DKG
>> ___
>> time-nuts mailing list -- time-nuts@lists.febo.com
>> To unsubscribe, go to 
>> http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
>> and follow the instructions there.
> 
> 
> ___
> time-nuts mailing list -- time-nuts@lists.febo.com
> To unsubscribe, go to 
> http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
> and follow the instructions there.
> 


___
time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe, go to 
http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
and follow the instructions there.

Re: [time-nuts] Antique pendulum clocks

[paul swed]

Heck as much as I like clocks I just want to see Adrians working HP 9815
calculator.
Other comment for me at least is a good clock is a marvel by itself. Adding
electronics removes the amazing engineering that went into the clock. By
good I mean clocks few of us can afford.
Though on time-nuts I have seen from time to time lucky people have found
these clocks at affordable prices.
Regards
Paul.

On Thu, Nov 21, 2019 at 2:00 AM Matthew D'Asaro  wrote:

> You are not the first to try this. The usual method for timing mechanical
> clocks is either acoustic (a microphone picks up the sound of the
> escapement) or optical (a sensor is blocked from light by the pendulum).
> The optical method is more accurate but more cumbersome to setup.
>
> Matthew
>
> Sent from Matthew D'Asaro's iPhone
>
> > On Nov 20, 2019, at 6:18 PM, Adrian Godwin  wrote:
> >
> >> On Thu, Nov 21, 2019 at 2:01 AM Bill Beam  wrote:
> >>
> >> Most people interested in this problem have been dead for about 200
> years.
> >>
> >> I knew there was a reason why I didn't feel so well lately ..
> >
> >
> > I have an electric pendulum clock by Bulle. A coil swings in a short arc,
> > following a curved magnetic polepiece. At some point, contacts close and
> > provide a timed sustaining impulse to the coil.
> >
> > Out of sheer pigheadedness, I am attempting to monitor the movement with
> > antique (perhaps not quite so antique) timing equipment. I have an HP456A
> > current probe to capture the impulse instance, an HP 5275A counter to
> > measure the period and an HP101A oscillator to provide a reference. ADEV
> > calculations might be done by an HP9815 calculator or perhaps an HP41 if
> I
> > can't find the 9815's parallel interface. Non-HP equipment is permitted
> but
> > nothing suitable has come up so far.
> >
> > A difficulty at the  moment is that the contacts bounce somewhat, making
> > the impulse timing poorly defined. I haven't yet got as far as seeing any
> > mechanically caused pattern to the errors.
> >
> > Thanks to Tom for giving me more distractions to read :)
> > ___
> > time-nuts mailing list -- time-nuts@lists.febo.com
> > To unsubscribe, go to
> http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
> > and follow the instructions there.
>
> ___
> time-nuts mailing list -- time-nuts@lists.febo.com
> To unsubscribe, go to
> http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
> and follow the instructions there.
>
___
time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe, go to 
http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
and follow the instructions there.

Re: [time-nuts] Difference in antennas

[Bob kb8tq]

Hi

Way back in time, the first gear out there to use what we now look at as 
“normal” antennas 
was survey gear. For various reasons they decided on a 12V power supply and 40 
to 50 db
of gain in the preamp mounted in the antenna. They also got into L1 / L2 pretty 
quickly. 

A bit later the cell phone (and later broadcast) guys got into this. In a 
location with a lot of 
RF (like a cell site) having a lot of gain at the antenna didn’t work all that 
well. IMD issues 
got into the act pretty quickly. In addition, front end filtering was required 
to reduce overload
issues. The focus was on L1 only so filtering was relatively easy.

There is a whole separate set of antennas that put a big chunk of the RF 
portion of the radio
in the antenna. Those still survive here and there. I have one of them and 
probably a couple
of dozen of the more “normal” antennas. 

As time marched on, supplying 12V to antennas became a bit less popular. Most 
of the cell 
guys went over to a 5V antenna supply. The net result was 12V 50 db survey 
antennas that did 
L1/L2 and much smaller 5V 25 db antennas for “timing”. The timing antennas 
didn’t do L1/L2 so
not going to work for survey. The survey antennas had way to much gain and no 
filtering so 
not going to work for a cell site. 

Indeed things did and do get crossed up in various pro and basement systems. 
With care and
the right set of circumstances things may work. In other cases the result can 
be an ongoing set
of systems issues over an entire network of stations. 

Prices for a good new survey antenna are up in the many thousands of dollars 
range. They have
very stable phase centers and (usually) test results to allow correction of any 
residual phase 
issues. This is part of what lets you get into the “couple of mm” range on a 
survey. 

For timing, you have to dig a bit and answer a few questions. Is your concern 
how close you
are to BIH? If so you will need to know all the delays in your system. This 
includes the delays
in the antenna filters and the preamp. Is your concern (or measure) the ADEV at 
1 second?
If so the delays are not a concern. Your antenna choice may be a bit different 
depending on
this focus.

Bob



> On Nov 21, 2019, at 1:25 AM, Taka Kamiya via time-nuts 
>  wrote:
> 
> I have been looking antennas.  Prices seem to range less than 30 dollars to 
> more than 500 dollars.  Some are 20db gain and some are 40 db gain.  Some are 
> specified as marine use only.  Some are specified as timing use.  Some 
> doesn't say anything at all.  Power supplies are different.
> Other than obvious, antenna is an antenna, isn't it?  It captures L1 signal, 
> amplify it and send it down the coax.  What makes one more costly than 
> others?  What makes one timing antenna and one navigation antenna?  It 
> doesn't make sense to me.  
> 
> I did some simple experiment with 26db, 40db, and magnetic stick on type.  I 
> didn't really see significant difference.  Signal level itself even wasn't 
> all that different.  I have nearly a clear sky view 360 degrees above 30 
> degrees above horizon.  In some directions, clear view to horizon.  My feed 
> is Timewave type.  So It may not be the best but nearly ideal.  
> 
> Can someone shed light on this topic?  (of course, I know some antenna has 
> integrated receiver.  I am not talking about those)
> 
> --- 
> (Mr.) Taka Kamiya
> KB4EMF / ex JF2DKG
> ___
> time-nuts mailing list -- time-nuts@lists.febo.com
> To unsubscribe, go to 
> http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
> and follow the instructions there.


___
time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe, go to 
http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
and follow the instructions there.

Re: [time-nuts] 90ms delay of time signal on phase-modulated carrier of BBC 198KHz transmission in the UK (was: DST change on DCF77)

[Peter Vince]

Hi Steve,

On Thu, 21 Nov 2019 at 01:00, Steve Allen  wrote:
>
> The current version ITU-R TF.460-6 says that time signals should
> not deviate by more than 1 ms from UTC.
>
> How can these broadcasts justify such a large offset?

The signal is only used (as far as I am aware, a few Time Nuts apart) for
controlling domestic electricity time switches for people on the
"Economy-7" tariff, which gives them cheaper electricity overnight for
storage heaters for seven hours.  As such, I suspect even a fraction of a
second is overkill.

 Regards,

  Peter
___
time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe, go to 
http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
and follow the instructions there.

Re: [time-nuts] Difference in antennas

[Forrest Christian (List Account)]

Like many things, price does not necessarily reflect a better antenna,
however there are differences between antennas.

One difference is in the quality of the filters in the antenna itself.
 This matters more when one is mounting an antenna at a communications site
than say at a home timing lab.  If you're at a site with a lot of RF noise,
if the antenna can pre-filter this out this will help the GPS receiver
dramatically.   I just pulled the spec sheet for one that I'm familiar with
and the filter in this one drops signals outside the GPS band by 65dB at
the band edges.

Another difference is the robustness of the higher end units, including
surviving nearby lightning strikes, operating at a wider voltage range, etc.

I'm not enough of a time-nut (yet) to be able to tell you if there is some
subtle difference between the antennas which would matter once you get to
some level of precision I don't have to deal with yet.

I've personally had good luck with the PCTEL/maxrad timing
reference antennas (GPS-TMG series).  I usually have been able to pick them
up off of ebay for not a lot of money.   These also seem to be often
re-sold with a lucent or symmetricom label or some other company's label on
them, mainly because they seem to be a supplier to all of these providers.
 I don't seem to recall ever having one of this type fail.That can't be
said of other ones I've bought from random no-name suppliers.


On Thu, Nov 21, 2019 at 12:00 AM Taka Kamiya via time-nuts <
time-nuts@lists.febo.com> wrote:

> I have been looking antennas.  Prices seem to range less than 30 dollars
> to more than 500 dollars.  Some are 20db gain and some are 40 db gain.
> Some are specified as marine use only.  Some are specified as timing use.
> Some doesn't say anything at all.  Power supplies are different.
> Other than obvious, antenna is an antenna, isn't it?  It captures L1
> signal, amplify it and send it down the coax.  What makes one more costly
> than others?  What makes one timing antenna and one navigation antenna?  It
> doesn't make sense to me.
>
> I did some simple experiment with 26db, 40db, and magnetic stick on type.
> I didn't really see significant difference.  Signal level itself even
> wasn't all that different.  I have nearly a clear sky view 360 degrees
> above 30 degrees above horizon.  In some directions, clear view to
> horizon.  My feed is Timewave type.  So It may not be the best but nearly
> ideal.
>
> Can someone shed light on this topic?  (of course, I know some antenna has
> integrated receiver.  I am not talking about those)
>
> ---
> (Mr.) Taka Kamiya
> KB4EMF / ex JF2DKG
> ___
> time-nuts mailing list -- time-nuts@lists.febo.com
> To unsubscribe, go to
> http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
> and follow the instructions there.
>


-- 
- Forrest
___
time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe, go to 
http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
and follow the instructions there.

Re: [time-nuts] 90ms delay of time signal on phase-modulated carrier of BBC 198KHz transmission in the UK (was: DST change on DCF77)

[Alan Melia via time-nuts]

It can be justified very simply that the phase mod data on 198kHz is NOT 
intended as a standard time distribution. As far as I am aware only the 
frequency accuracy is covered in the NPL contract. Even that no longer seems 
to be monitored and offsets published.


Time distribution is on MSF 60kHz

Alan
G3NYK

- Original Message - 
From: "Steve Allen" 
To: "Discussion of precise time and frequency measurement" 


Sent: Wednesday, November 20, 2019 7:26 PM
Subject: Re: [time-nuts] 90ms delay of time signal on phase-modulated 
carrier of BBC 198KHz transmission in the UK (was: DST change on DCF77)




On Wed 2019-11-20T11:35:51+ Peter Vince hath writ:
As I mentioned in a previous message about observed anomalies with the 
DST

change on DCF77, Pieter-Tjerk in the Netherlands noted that the time
encoded on the phase-modulated carrier of the BBC's 198KHz signal in the 
UK

was about 900 milliseconds early.  Having queried that with a contact in
the BBC, a problem was found and corrected, but Pieter-Tjerk reports the
signal is now about 90 milliseconds late.  A further query with my 
contact

reveals that this is to be expected.


90 milliseconds is a larger offset than was seen in the broadcasts that
the BIH monitored during most of its existence as seen in these plots
https://www.ucolick.org/~sla/leapsecs/BHsHn05p142.html

This report indicates that the clock time blocks are intended to
provide UTC
https://downloads.bbc.co.uk/rd/pubs/reports/1984-19.pdf

The current version ITU-R TF.460-6 says that time signals should
not deviate by more than 1 ms from UTC.

How can these broadcasts justify such a large offset?

--
Steve Allen  WGS-84 (GPS)
UCO/Lick Observatory--ISB 260  Natural Sciences II, Room 165  Lat 
+36.99855
1156 High Street   Voice: +1 831 459 3046 
Lng -122.06015

Santa Cruz, CA 95064   https://www.ucolick.org/~sla/  Hgt +250 m

___
time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe, go to 
http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
and follow the instructions there. 



___
time-nuts mailing list -- time-nuts@lists.febo.com
To unsubscribe, go to 
http://lists.febo.com/mailman/listinfo/time-nuts_lists.febo.com
and follow the instructions there.