Re: [time-nuts] Why is holdover LED on HP 58503A not lit, when GPS lock is unlit too?

[Dr. David Kirkby (Kirkby Microwave Ltd)]

On 18 December 2016 at 22:41, Dr. David Kirkby (Kirkby Microwave Ltd) <
drkir...@kirkbymicrowave.co.uk> wrote:

> It is looking much better now. I
>
> 1) Powered off
> 2) Left off for 30 s
> 3) Pulled antenna out.
> 4) Powered on
> 5) Connected antenna, making sure if was firmly screwed in.
>
> It then got GPS lock in a few minutes. It is running at reduced accuracy,
> with the survey only 9.7% complete, but it is looking more hopeful.
>

This does appear now to be working - see below. I'm not exactly sure what
was the secret to getting this to work, but the above procedure seemed ok.


scpi >  SYSTEM:STATUS?
--- Receiver Status
---

SYNCHRONIZATION . [ Outputs
Valid ]
SmartClock Mode ___   Reference Outputs
___
>> Locked to GPS  TFOM 3
FFOM 0
   Recovery   1PPS TI -8.3 ns relative to
GPS
   Holdover   HOLD THR 1.000 us
   Power-up   Holdover Uncertainty

  Predict  9.6 us/initial 24 hrs

ACQUISITION  [ GPS 1PPS
Valid ]
Tracking: 6    Not Tracking: 2    Time _ +1 leap second
pending
PRN  El  Az   SS   PRN  El  AzUTC  23:11:07 19 Dec
2016
  2  31  69   83 6  15  34GPS 1PPS Synchronized to UTC
 12  41  80  11032  27 234ANT DLY  0 ns
 14  37 266   81  Position

 25  83  33  127  MODE Hold
 29  55 195  135
 31  42 301   75  LAT  N  51:39:04.198
  LON  E   0:46:36.358
ELEV MASK 10 deg  HGT   +45.42 m
(MSL)
HEALTH MONITOR . [
OK ]
Self Test: OKInt Pwr: OK   Oven Pwr: OK   OCXO: OK   EFC: OK   GPS Rcv:
OK
scpi >
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Re: [time-nuts] Why is holdover LED on HP 58503A not lit, when GPS lock is unlit too?

[Hal Murray]

drkir...@kirkbymicrowave.co.uk said:
> I assume it wont start until it has tracked sufficient number of satellites.

There is a chicken-egg problem with getting started.  The satellites tell you 
where they are, but you need to know where they are and where you are in 
order to calculate the Doppler offset so you know what frequency to listen to.

The difference between warm start and cold start is that for a warm start the 
receiver has a 32KHz clock and has saved its last position and the satellite 
orbit data in battery backed RAM.

-- 
These are my opinions.  I hate spam.



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Re: [time-nuts] Why is holdover LED on HP 58503A not lit, when GPS lock is unlit too?

[Dr. David Kirkby (Kirkby Microwave Ltd)]

It is looking much better now. I

1) Powered off
2) Left off for 30 s
3) Pulled antenna out.
4) Powered on
5) Connected antenna, making sure if was firmly screwed in.

It then got GPS lock in a few minutes. It is running at reduced accuracy,
with the survey only 9.7% complete, but it is looking more hopeful.

I can't help feeling there should have been more informative status
available by the LEDs. The fact it is locked, but at reduced accuracy,
should really be visable from the front panel IMHO. Anyway, it seems to be
getting there - see below.

scpi >  SYSTEM:STATUS?
--- Receiver Status
---

SYNCHRONIZATION  [ Outputs Valid/Reduced
Accuracy ]
SmartClock Mode ___   Reference Outputs
___
>> Locked to GPS: stabilizing frequency   TFOM 3
FFOM 1
   Recovery   1PPS TI -15.9 ns relative to
GPS
   Holdover   HOLD THR 1.000 us
   Power-up   Holdover Uncertainty

  Predict  432.0 us/initial 24
hrs

ACQUISITION  [ GPS 1PPS
Valid ]
Tracking: 6    Not Tracking: 3    Time _ +1 leap second
pending
PRN  El  Az   SS   PRN  El  AzUTC  22:39:23 18 Dec
2016
  2  28  87   86 6  20  48GPS 1PPS Synchronized to UTC
 12  57  70  11924  24 137ANT DLY  0 ns
 14  39 287  10631  27 303Position

 25  76 284   96  MODE Survey:9.7%
complete
 29  37 194   79
 32  39 249  109  AVG LAT  N  51:39:04.205
  AVG LON  E   0:46:36.347
ELEV MASK 10 deg  AVG HGT   +42.42 m
(MSL)
HEALTH MONITOR . [
OK ]
Self Test: OKInt Pwr: OK   Oven Pwr: OK   OCXO: OK   EFC: OK   GPS Rcv:
OK
scpi >
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Re: [time-nuts] Why is holdover LED on HP 58503A not lit, when GPS lock is unlit too?

[Dr. David Kirkby (Kirkby Microwave Ltd)]

On 18 December 2016 at 18:19, Dan Rae  wrote:

> On 12/18/2016 9:34 AM, Dr. David Kirkby (Kirkby Microwave Ltd) wrote:
>
>> 
>> *12  -- ---MODE Survey:  0%
>> complete
>>
>>
> If it's still showing that after being on for five hours, maybe it needs
> to be explicitly told to start a survey?
>
> dr
>


I seem to be having some issues now with this. I've reset it, and entered
the approximate latitude, longitude, height, as well as date and time. The
commands below were executed, although NOT necessarily in the order give.


E-113> GPS:INIT:DATe 2016,12,18
E-113> gps:init:time 19,18,35
E-113> SYSTEM:PRESET
scpi > DIAG:LOG:READ:ALL?
Log status: 2   entries

Log 001:19970504.00:00:00:  Log cleared
Log 002:19970504.00:00:00:  System preset

The receiver seems to find satellites fairly quickly, tries to track them,
and is showing reasonable values for the things I set, like date, time,
position etc. However,  the receiver doesn't seem able to track any
satellites, so not surprisingly the survey never starts. I assume it wont
start until it has tracked sufficient number of satellites.

scpi > SYSTEM:STATUS?
--- Receiver Status
---

SYNCHRONIZATION ... [ Outputs
Invalid ]
SmartClock Mode ___   Reference Outputs
___
   Locked TFOM 9
FFOM 3
   Recovery   1PPS TI  --
   Holdover   HOLD THR 1.000 us
>> Power-up: GPS acquisition  Holdover Uncertainty

  Predict  --

ACQUISITION .. [ GPS 1PPS
Invalid ]
Tracking: 0    Not Tracking: 12 ___   Time

   PRN  El  Az  PRN  El  Az   UTC  21:57:41 [?] 18 Dec
2016
 6  20  67   12  76  56   GPS 1PPS Invalid: not tracking
   * 7  -- ---   14  32 307   ANT DLY  0 ns
   * 8  -- ---   24  42 129   Position

   * 9  -- ---   25  58 259   MODE Survey:  0%
complete
   *10  -- ---  *31  10 299Suspended: track <4
sats
   *11  -- ---   32  45 274   INIT LAT N  51:39:03.825
  INIT LON E   0:46:36.277
ELEV MASK 10 deg   *attempting to track   INIT HGT  +29.99 m
(MSL)
HEALTH MONITOR . [
OK ]
Self Test: OKInt Pwr: OK   Oven Pwr: OK   OCXO: OK   EFC: OK   GPS Rcv:
OK


It will run overnight. Perhaps tomorrow it will sort itself out, but I'm
not too hopeful.


Dr. David Kirkby Ph.D CEng MIET
Kirkby Microwave Ltd
Registered office: Stokes Hall Lodge, Burnham Rd, Althorne, Essex, CM3 6DT,
UK.
Registered in England and Wales, company number 08914892.
http://www.kirkbymicrowave.co.uk/
Tel: 07910 441670 / +44 7910 441670 (0900 to 2100 GMT only please)
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Re: [time-nuts] Why is holdover LED on HP 58503A not lit, when GPS lock is unlit too?

[Dan Rae]

On 12/18/2016 9:34 AM, Dr. David Kirkby (Kirkby Microwave Ltd) wrote:


*12  -- ---MODE Survey:  0%
complete

If it's still showing that after being on for five hours, maybe it needs 
to be explicitly told to start a survey?


dr
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Re: [time-nuts] Why is holdover LED on HP 58503A not lit, when GPS lock is unlit too?

[Dr. David Kirkby (Kirkby Microwave Ltd)]

On 18 December 2016 at 14:31, Tim Shoppa  wrote:

> A common misconception, is that holdover is the opposite of GPS lock.
> Sometimes we might even talk about the two as if we're in one or the other.
> But really the power-on state, is that we're in neither holdover or GPS
> lock.
>
> Holdover means the smartclock previously had GPS lock and had used it to
> characterize the aging of the OCXO, and is maintaining the EFC
> extrapolation, such that it believes it can still produce accurate time and
> frequency through the GPS loss.
>
> The state of your clock at the moment, is that it has never had GPS lock
> since regaining power, it does not know what time it is, and it has not
> characterized or extrapolated the aging of the OCXO. So it is definitely
> not in holdover.
>
> Tim N3QE
>

Cheers Tim, that makes sense.

I'm a bit concerned it has not managed to track a single satellite, despite
it has been on 5 hours or so. But perhaps things have improved, as its not
attempting to track 6 (PRN=15, 2, 21, 25, 26 and 28), whereas before it was
attempting to track just with a PRN of 32. I'm hoping its current status
(see below), is looking more hopeful than what it was before.

scpi >
scpi > SYSTEM:STATUS?
--- Receiver Status
---

SYNCHRONIZATION ... [ Outputs
Invalid ]
SmartClock Mode ___   Reference Outputs
___
   Locked TFOM 9
FFOM 3
   Recovery   1PPS TI  --
   Holdover   HOLD THR 1.000 us
>> Power-up: GPS acquisition  Holdover Uncertainty

  Predict  --

ACQUISITION .. [ GPS 1PPS
Invalid ]
Tracking: 0    Not Tracking: 6    Time _ +1 leap second
pending
   PRN  El  AzUTC  14:43:22 [?] 01 Jan
1998
   *15  -- ---GPS 1PPS Invalid: not tracking
   *20  -- ---ANT DLY  0 ns
   *21  -- ---Position

   *25  -- ---MODE Survey:  0%
complete
   *26  -- --- Suspended: track <4
sats
   *28  -- ---INIT LAT N  51:39:03.825
  INIT LON E   0:46:36.278
ELEV MASK 10 deg   *attempting to track   INIT HGT  -14.04 m
(MSL)
HEALTH MONITOR . [
OK ]
Self Test: OKInt Pwr: OK   Oven Pwr: OK   OCXO: OK   EFC: OK   GPS Rcv:
OK
scpi > SYSTEM:STATUS?
--- Receiver Status
---

SYNCHRONIZATION ... [ Outputs
Invalid ]
SmartClock Mode ___   Reference Outputs
___
   Locked TFOM 9
FFOM 3
   Recovery   1PPS TI  --
   Holdover   HOLD THR 1.000 us
>> Power-up: GPS acquisition  Holdover Uncertainty

  Predict  --

ACQUISITION .. [ GPS 1PPS
Invalid ]
Tracking: 0    Not Tracking: 6    Time _ +1 leap second
pending
   PRN  El  AzUTC  16:59:08 [?] 01 Jan
1998
   * 8  -- ---GPS 1PPS Invalid: not tracking
   *10  -- ---ANT DLY  0 ns
   *11  -- ---Position

   *12  -- ---MODE Survey:  0%
complete
   *13  -- --- Suspended: track <4
sats
   *30  -- ---INIT LAT N  51:39:03.825
  INIT LON E   0:46:36.278
ELEV MASK 10 deg   *attempting to track   INIT HGT  -14.04 m
(MSL)
HEALTH MONITOR . [
OK ]
Self Test: OKInt Pwr: OK   Oven Pwr: OK   OCXO: OK   EFC: OK   GPS Rcv:
OK
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Re: [time-nuts] Why is holdover LED on HP 58503A not lit, when GPS lock is unlit too?

[Dr. David Kirkby (Kirkby Microwave Ltd)]

On 18 December 2016 at 17:34, Dr. David Kirkby (Kirkby Microwave Ltd) <
drkir...@kirkbymicrowave.co.uk> wrote:

> But perhaps things have improved, as its not attempting to track 6
> (PRN=15, 2, 21, 25, 26 and 28), whereas before it was attempting to track
> just with a PRN of 32. I'm hoping its current status (see below), is
> looking more hopeful than what it was before.
>

I mean it is NOW attempting to track 6 !!! Almost the opposite of what I
wrote.

I'm guessing it gave up attempting to track the satellite with a PRN of 32.

Dave
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Re: [time-nuts] Why is holdover LED on HP 58503A not lit, when GPS lock is unlit too?

[Tim Shoppa]

A common misconception, is that holdover is the opposite of GPS lock.
Sometimes we might even talk about the two as if we're in one or the other.
But really the power-on state, is that we're in neither holdover or GPS
lock.

Holdover means the smartclock previously had GPS lock and had used it to
characterize the aging of the OCXO, and is maintaining the EFC
extrapolation, such that it believes it can still produce accurate time and
frequency through the GPS loss.

The state of your clock at the moment, is that it has never had GPS lock
since regaining power, it does not know what time it is, and it has not
characterized or extrapolated the aging of the OCXO. So it is definitely
not in holdover.

Tim N3QE

On Sun, Dec 18, 2016 at 8:01 AM, Dr. David Kirkby (Kirkby Microwave Ltd) <
drkir...@kirkbymicrowave.co.uk> wrote:

> My 58503 GPS time/frequency reference had its power disconnected a few
> times yesterday as I moved things in the lab. At the modem the status of
> the LEDs are
>
> * Power green
> * GPS lock - not lit
> * Holdover - not lit
> * Alarm - not lit.
>
> That is what the manual says will happen  when power is first applied, but
> I'm puzzled why.
>
> The SYSTEM:STATUS? shows the information at the end of this email. What I
> can't understand is why the holdover light is not lit, when clearly its not
> tracking any satellites. It seems logical to me that holdover should be on,
> when GPS lock is not, and visa versa. But that does not seem to be the
> case.
>
> Looking at the data below, the date/time is obviously wrong (01 Jan 1998),
> the height at -14.04 m  (MSL) is wrong, but latitude and longitude look
> about right, although they are certainly not exactly agreeing with Google
> maps, which show 51°39'04.1"N+0°46'36.4"E.
>
> I must be misunderstanding the purpose of these lights.
>
> I'm also a bit puzzled it has been on about 1.5 hours, and can't seem to
> find a single satellite. The antenna is fairly clear of anything else, and
> it was certainly working yesterday, with the power and GPS lock LEDs both
> lit.
>
> Any ideas what's going on?
>
> scpi > SYSTEM:STATUS?
> --- Receiver Status
> ---
>
> SYNCHRONIZATION ... [ Outputs
> Invalid ]
> SmartClock Mode ___   Reference Outputs
> ___
>Locked TFOM 9
> FFOM 3
>Recovery   1PPS TI  --
>Holdover   HOLD THR 1.000 us
> >> Power-up: GPS acquisition  Holdover Uncertainty
> 
>   Predict  --
>
> ACQUISITION .. [ GPS 1PPS
> Invalid ]
> Tracking: 0    Not Tracking: 1    Time _ +1 leap second
> pending
>PRN  El  AzUTC  12:59:16 [?] 01 Jan
> 1998
>*32  -- ---GPS 1PPS Invalid: not
> tracking
>   ANT DLY  0 ns
>   Position
> 
>   MODE Survey:  0%
> complete
>Suspended: track <4
> sats
>   INIT LAT N  51:39:03.825
>   INIT LON E   0:46:36.278
> ELEV MASK 10 deg   *attempting to track   INIT HGT  -14.04 m
> (MSL)
> HEALTH MONITOR . [
> OK ]
> Self Test: OKInt Pwr: OK   Oven Pwr: OK   OCXO: OK   EFC: OK   GPS Rcv:
> OK
> scpi >
>
>
>
> Dr. David Kirkby Ph.D CEng MIET
> Kirkby Microwave Ltd
> Registered office: Stokes Hall Lodge, Burnham Rd, Althorne, Essex, CM3 6DT,
> UK.
> Registered in England and Wales, company number 08914892.
> http://www.kirkbymicrowave.co.uk/
> Tel: 07910 441670 / +44 7910 441670 (0900 to 2100 GMT only please)
> ___
> 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.
>
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Re: [time-nuts] Why is holdover LED on HP 58503A not lit, when GPS lock is unlit too?

[Artek Manuals]

I believe  the "Holdover" function only occurs when you you loose just 
the  satellites


Once locked disconnect the antenna for a minute and you will see the 
holdover LED light.


IF the unit looses POWER it has no way of of powering the oscillator and 
its ovens ( to do a holdover) and has no way of knowing how long the 
unit has been off when re-powered until it goes through a complete 
acquisition/re-sync cycle.


DAVE

manu...@artekmanuals.com


On 12/18/2016 8:01 AM, Dr. David Kirkby (Kirkby Microwave Ltd) wrote:

My 58503 GPS time/frequency reference had its power disconnected a few
times yesterday as I moved things in the lab. At the modem the status of
the LEDs are

* Power green
* GPS lock - not lit
* Holdover - not lit
* Alarm - not lit.

That is what the manual says will happen  when power is first applied, but
I'm puzzled why.

The SYSTEM:STATUS? shows the information at the end of this email. What I
can't understand is why the holdover light is not lit, when clearly its not
tracking any satellites. It seems logical to me that holdover should be on,
when GPS lock is not, and visa versa. But that does not seem to be the
case.

Looking at the data below, the date/time is obviously wrong (01 Jan 1998),
the height at -14.04 m  (MSL) is wrong, but latitude and longitude look
about right, although they are certainly not exactly agreeing with Google
maps, which show 51°39'04.1"N+0°46'36.4"E.

I must be misunderstanding the purpose of these lights.

I'm also a bit puzzled it has been on about 1.5 hours, and can't seem to
find a single satellite. The antenna is fairly clear of anything else, and
it was certainly working yesterday, with the power and GPS lock LEDs both
lit.

Any ideas what's going on?

scpi > SYSTEM:STATUS?
--- Receiver Status
---

SYNCHRONIZATION ... [ Outputs
Invalid ]
SmartClock Mode ___   Reference Outputs
___
Locked TFOM 9
FFOM 3
Recovery   1PPS TI  --
Holdover   HOLD THR 1.000 us

Power-up: GPS acquisition  Holdover Uncertainty


   Predict  --

ACQUISITION .. [ GPS 1PPS
Invalid ]
Tracking: 0    Not Tracking: 1    Time _ +1 leap second
pending
PRN  El  AzUTC  12:59:16 [?] 01 Jan
1998
*32  -- ---GPS 1PPS Invalid: not tracking
   ANT DLY  0 ns
   Position

   MODE Survey:  0%
complete
Suspended: track <4
sats
   INIT LAT N  51:39:03.825
   INIT LON E   0:46:36.278
ELEV MASK 10 deg   *attempting to track   INIT HGT  -14.04 m
(MSL)
HEALTH MONITOR . [
OK ]
Self Test: OKInt Pwr: OK   Oven Pwr: OK   OCXO: OK   EFC: OK   GPS Rcv:
OK
scpi >



Dr. David Kirkby Ph.D CEng MIET
Kirkby Microwave Ltd
Registered office: Stokes Hall Lodge, Burnham Rd, Althorne, Essex, CM3 6DT,
UK.
Registered in England and Wales, company number 08914892.
http://www.kirkbymicrowave.co.uk/
Tel: 07910 441670 / +44 7910 441670 (0900 to 2100 GMT only please)
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--
Dave
manu...@artekmanuals.com
www.ArtekManuals.com

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[time-nuts] Why is holdover LED on HP 58503A not lit, when GPS lock is unlit too?

[Dr. David Kirkby (Kirkby Microwave Ltd)]

My 58503 GPS time/frequency reference had its power disconnected a few
times yesterday as I moved things in the lab. At the modem the status of
the LEDs are

* Power green
* GPS lock - not lit
* Holdover - not lit
* Alarm - not lit.

That is what the manual says will happen  when power is first applied, but
I'm puzzled why.

The SYSTEM:STATUS? shows the information at the end of this email. What I
can't understand is why the holdover light is not lit, when clearly its not
tracking any satellites. It seems logical to me that holdover should be on,
when GPS lock is not, and visa versa. But that does not seem to be the
case.

Looking at the data below, the date/time is obviously wrong (01 Jan 1998),
the height at -14.04 m  (MSL) is wrong, but latitude and longitude look
about right, although they are certainly not exactly agreeing with Google
maps, which show 51°39'04.1"N+0°46'36.4"E.

I must be misunderstanding the purpose of these lights.

I'm also a bit puzzled it has been on about 1.5 hours, and can't seem to
find a single satellite. The antenna is fairly clear of anything else, and
it was certainly working yesterday, with the power and GPS lock LEDs both
lit.

Any ideas what's going on?

scpi > SYSTEM:STATUS?
--- Receiver Status
---

SYNCHRONIZATION ... [ Outputs
Invalid ]
SmartClock Mode ___   Reference Outputs
___
   Locked TFOM 9
FFOM 3
   Recovery   1PPS TI  --
   Holdover   HOLD THR 1.000 us
>> Power-up: GPS acquisition  Holdover Uncertainty

  Predict  --

ACQUISITION .. [ GPS 1PPS
Invalid ]
Tracking: 0    Not Tracking: 1    Time _ +1 leap second
pending
   PRN  El  AzUTC  12:59:16 [?] 01 Jan
1998
   *32  -- ---GPS 1PPS Invalid: not tracking
  ANT DLY  0 ns
  Position

  MODE Survey:  0%
complete
   Suspended: track <4
sats
  INIT LAT N  51:39:03.825
  INIT LON E   0:46:36.278
ELEV MASK 10 deg   *attempting to track   INIT HGT  -14.04 m
(MSL)
HEALTH MONITOR . [
OK ]
Self Test: OKInt Pwr: OK   Oven Pwr: OK   OCXO: OK   EFC: OK   GPS Rcv:
OK
scpi >



Dr. David Kirkby Ph.D CEng MIET
Kirkby Microwave Ltd
Registered office: Stokes Hall Lodge, Burnham Rd, Althorne, Essex, CM3 6DT,
UK.
Registered in England and Wales, company number 08914892.
http://www.kirkbymicrowave.co.uk/
Tel: 07910 441670 / +44 7910 441670 (0900 to 2100 GMT only please)
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