Re: [time-nuts] Einstein Special on PBS

[Chris Caudle]

On Fri, November 27, 2015 9:37 am, Mike Feher wrote:
> the period of the hyperfine transitions must change as well, to
> make the defined second longer or shorter. So, in these examples the
> elevation does not change the time, but the way the atoms behave.

That gets into a philosophical question of what defines time. You seem to
take the view that time is some kind of Platonic ideal, and we can compare
how closely a physical phenomenon matches that ideal.  But how do you
define or measure time other than changes from one physical state to
another?  And if every state change process down to the quantum atomic
level changes rate when referenced to the identical processes in a
different gravity potential or acceleration, how do you define which is
the "correct" rate?  How would you objectively tell the difference between
time passing at a different rate, and the Platonic ideal time passing at a
constant rate and literally every physical process progressing at a
different rate referred to the Platonic ideal time?

-- 
Chris Caudle


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Re: [time-nuts] SMD TADD-1 distribution amplifier - seeking comments and suggestions?

[Bob Camp]

Hi

Somethings to consider:  

How quiet are the sources you will be running through this amplifier?

How predictable are the levels of the sources? 

How important is isolation?

Do you need lowpass / bandpass filtering (are there other RF sources running 
around?)?

Is ESD on the coax an issue (do you need a high value resistor here or there?) ?

Bob

> On Nov 30, 2015, at 3:02 PM, Anders Wallin  
> wrote:
> 
> HI all,
> I need to build a few distribution amplifiers (>90% for 10MHz, sometimes
> maybe 5MHz) and instead of reinventing the wheel I decided to try to
> modernize the TADD-1 into an all (almost) SMD design. Here are some draft
> sketches:
> http://www.anderswallin.net/2015/11/frequency-distribution-amplifier-plans-a-k-a-smd-tadd-1/
> 
> Does this sound/look reasonable or crazy?
> Any suggestions for op-amps to try and/or compare to the AD8055?
> What causes the extra phase-noise below 1 Hz offset in John A's result:
> https://www.febo.com/pages/amplifier_phase_noise/amplifier_phase_noise.png
> 
> Suggestions for a low noise DC-regulator circuit? The 12-24VDC supplied to
> this board will most likely come from a switched-mode PSU, so filtering of
> common-mode noise is mandatory.
> I found the TI LP38798 shown in the schematic by googling - if someone has
> a proven a measured design that would be a safer choice. In any case more
> filtering (e.g. ferriites) is probably a good idea.
> 
> This design will be available on my blog or on github when it is done - if
> anyone is interested.
> 
> Thanks,
> Anders
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[time-nuts] Navsymm Proteus

[Graham Baxter]

Does anyone know the purpose of the jumper to the left of the three power
supply jumpers. I have one receiver which does a periodic lurch of its time
deviation, but when I fitted a jumper it apparently stopped. Was this a
coincidence?

Graham Baxter
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[time-nuts] GPS down converter question

[paul swed]

I am looking at building a GPS down converter.
LO 1500 Mhz locked to a 10 MHz ref.
The IF will be at 75.42 Mhz how wide should it be?

My question is simple.

What should the IF pass band bandwidth be?
Not sure if it should be 3-4 Mhz, 10 or 15 wide.

Thanks
Paul
WB8TSL
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[time-nuts] SMD TADD-1 distribution amplifier - seeking comments and suggestions?

[Anders Wallin]

HI all,
I need to build a few distribution amplifiers (>90% for 10MHz, sometimes
maybe 5MHz) and instead of reinventing the wheel I decided to try to
modernize the TADD-1 into an all (almost) SMD design. Here are some draft
sketches:
http://www.anderswallin.net/2015/11/frequency-distribution-amplifier-plans-a-k-a-smd-tadd-1/

Does this sound/look reasonable or crazy?
Any suggestions for op-amps to try and/or compare to the AD8055?
What causes the extra phase-noise below 1 Hz offset in John A's result:
https://www.febo.com/pages/amplifier_phase_noise/amplifier_phase_noise.png

Suggestions for a low noise DC-regulator circuit? The 12-24VDC supplied to
this board will most likely come from a switched-mode PSU, so filtering of
common-mode noise is mandatory.
I found the TI LP38798 shown in the schematic by googling - if someone has
a proven a measured design that would be a safer choice. In any case more
filtering (e.g. ferriites) is probably a good idea.

This design will be available on my blog or on github when it is done - if
anyone is interested.

Thanks,
Anders
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Re: [time-nuts] GPS down converter question

[paul swed]

Magnus you are right.
Its interesting in that several parts are easily available at
semi-reasonable cost.
Mini- circuits has a all in one synthesizer module dsn-2036 for the LO and
they also have very nice IF filters. The BPF-a76 appears to be exactly the
right bandwidth for a GPS IF.
There are some things to work through but they seem reasonable.
Regards
Paul.
WB8TSL

On Mon, Nov 30, 2015 at 5:02 PM, Magnus Danielson <
mag...@rubidium.dyndns.org> wrote:

> Paul,
>
> Many GPS receivers only use 2,046 MHz bandwidth, but some use the full
> 20,46 MHz even if they only do C/A. Guessing that you are working on
> down-conversion for an old box, then 2,046 MHz will be your answer.
>
> Cheers,
> Magnus
>
>
> On 11/30/2015 06:37 PM, paul swed wrote:
>
>> I am looking at building a GPS down converter.
>> LO 1500 Mhz locked to a 10 MHz ref.
>> The IF will be at 75.42 Mhz how wide should it be?
>>
>> My question is simple.
>>
>> What should the IF pass band bandwidth be?
>> Not sure if it should be 3-4 Mhz, 10 or 15 wide.
>>
>> Thanks
>> Paul
>> WB8TSL
>> ___
>> time-nuts mailing list -- time-nuts@febo.com
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>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>> and follow the instructions there.
>>
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> and follow the instructions there.
>
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[time-nuts] M12M Replacement Receiver Firmware Update

[Keith Loiselle]

Guys,

We have published an updated firmware version 1.1 for the M12M Replacement
Receiver that is available from the support page of the Jackson Labs
website:
www.jackson-labs.com/index.php/support

The updated firmware is available under Firmware Downloads and a
description of the improvements are listed under the ECN section.  You can
also find firmware update instructions on page 39 of the user manual here:
http://www.jackson-labs.com/assets/uploads/main/M12M_replacement_UserManual.pdf

The main improvement is correcting a problem with the LED display that will
cause the display to malfunction during continuous use.  With this problem,
only the LED display is affected, and the unit will otherwise continue to
operate normally.

Let me know if you have any feedback or questions.

Thanks,
Keith
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Re: [time-nuts] GPS down converter question

[Magnus Danielson]

Paul,

Many GPS receivers only use 2,046 MHz bandwidth, but some use the full 
20,46 MHz even if they only do C/A. Guessing that you are working on 
down-conversion for an old box, then 2,046 MHz will be your answer.


Cheers,
Magnus

On 11/30/2015 06:37 PM, paul swed wrote:

I am looking at building a GPS down converter.
LO 1500 Mhz locked to a 10 MHz ref.
The IF will be at 75.42 Mhz how wide should it be?

My question is simple.

What should the IF pass band bandwidth be?
Not sure if it should be 3-4 Mhz, 10 or 15 wide.

Thanks
Paul
WB8TSL
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Re: [time-nuts] SMD TADD-1 distribution amplifier - seeking comments and suggestions?

[Bruce Griffiths]

Anders
U101 only needs to have a gain of 1 at dc so replace R104 and R105 with a 
capacitor connected to ground.
Adjust the other components of the gain determining network accordingly.Also 
the junction of the power supply divider R102 and R103 should be heavily 
capacitively bypassed to ground and a resistor placed between this junction and 
U101's noninverting input.

Excess Sub Hz PN is usually due power supply noise or thermal fluctuations due 
to air currents/ convection.
Most of the so called super regulator circuits  should be more than quiet 
enough with an LM329 reference.A damped LCR filter at the input will improve 
the PSRR at switchmode output frequencies.

Bruce
 


On Tuesday, 1 December 2015 9:02 AM, Anders Wallin 
 wrote:
 

 HI all,
I need to build a few distribution amplifiers (>90% for 10MHz, sometimes
maybe 5MHz) and instead of reinventing the wheel I decided to try to
modernize the TADD-1 into an all (almost) SMD design. Here are some draft
sketches:
http://www.anderswallin.net/2015/11/frequency-distribution-amplifier-plans-a-k-a-smd-tadd-1/

Does this sound/look reasonable or crazy?
Any suggestions for op-amps to try and/or compare to the AD8055?
What causes the extra phase-noise below 1 Hz offset in John A's result:
https://www.febo.com/pages/amplifier_phase_noise/amplifier_phase_noise.png

Suggestions for a low noise DC-regulator circuit? The 12-24VDC supplied to
this board will most likely come from a switched-mode PSU, so filtering of
common-mode noise is mandatory.
I found the TI LP38798 shown in the schematic by googling - if someone has
a proven a measured design that would be a safer choice. In any case more
filtering (e.g. ferriites) is probably a good idea.

This design will be available on my blog or on github when it is done - if
anyone is interested.

Thanks,
Anders
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Re: [time-nuts] GPS down converter question

[Alex Pummer]

Meinberg down-converter: IF 34MHz: 
http://digilander.libero.it/maurit0/transito%20ebay/GPS%20R%20Meinberg/gpsant.pdf

73
KJ6UHN
Alex

On 11/30/2015 2:02 PM, Magnus Danielson wrote:

Paul,

Many GPS receivers only use 2,046 MHz bandwidth, but some use the full 
20,46 MHz even if they only do C/A. Guessing that you are working on 
down-conversion for an old box, then 2,046 MHz will be your answer.


Cheers,
Magnus

On 11/30/2015 06:37 PM, paul swed wrote:

I am looking at building a GPS down converter.
LO 1500 Mhz locked to a 10 MHz ref.
The IF will be at 75.42 Mhz how wide should it be?

My question is simple.

What should the IF pass band bandwidth be?
Not sure if it should be 3-4 Mhz, 10 or 15 wide.

Thanks
Paul
WB8TSL
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11/30/15


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Re: [time-nuts] GPS down converter question

[Peter Monta]

>
> What should the IF pass band bandwidth be?
>

For GPS C/A with wide correlator, about 2 MHz; if you want Galileo BOC and
(eventually) GPS L1C, or legacy C/A with narrow correlator, about 8 MHz;
for GPS P code about 20 MHz.  Books on GNSS software receivers will detail
the many tradeoffs available---if you're starting out with a
proof-of-concept lab receiver, go for 8 MHz.

Cheers,
Peter
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Re: [time-nuts] GPS down converter question

[Magnus Danielson]

Hi,

This is a side-track to Pauls original question, but maybe a nice little 
point to make now that Peter touched on the subject.


To elaborate a little on C/A and multipath surpression.
The multipath surpression of the receiver depends on code rate, 
bandwidth and correlator spacing. P-code is able to surpress more, and 
the C/A code errors look about the same as the P-code, but scaled 
accordingly. Increasing the bandwidth helps to reduce the C/A errors, 
but taking the next step of using narrow correlators further reduces the 
error. This is shown already in the classical Spiliker book, but further 
readings from Novatel could be nice.


Increasing the bandwidth and narrowing the early and late correlator 
taps both have the effect of reducing the time over which energy goes 
into the E-L difference, and hence reducing the impact of multipath into 
the solution.


Cheers,
Magnus

On 12/01/2015 06:00 AM, Peter Monta wrote:


What should the IF pass band bandwidth be?



For GPS C/A with wide correlator, about 2 MHz; if you want Galileo BOC and
(eventually) GPS L1C, or legacy C/A with narrow correlator, about 8 MHz;
for GPS P code about 20 MHz.  Books on GNSS software receivers will detail
the many tradeoffs available---if you're starting out with a
proof-of-concept lab receiver, go for 8 MHz.

Cheers,
Peter
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