[time-nuts] Lucent RFTG-m-XO GPSDO

Peter Bell bell.peter at gmail.com
Tue Oct 11 08:49:02 EDT 2011


The Rx was defective - I just got the new one, hooked it up to my
little test rig anf the antenna, and it happily picked up satellites
and got a position fix.

Swapped it into the box, and found a TTL level copy of the RX data
stream from the encore on pin 2 of the interface connector, so hooked
that up to a TTL->RS232 converter so I could monitor what was
happening.  It all seemed to be tracking OK, although the "No GPS" LED
was still on, so I just left it and after a couple of hours the LED
went out.

Next step is getting the Rb working :)


On Mon, Oct 10, 2011 at 2:41 AM, k4cle at aol.com <k4cle at aol.com> wrote:
> Hi Peter, yes it sounds like the UT+ is defective if it never gets any sats.  You can probably find one on eBay.  Someone probably fired RF into the receiver front-end and zapped it.  I think the antenna you are using should be OK.
>
> I will look for my drawings on this unit and send copies to you.  And I know I have the software too, just need to find it!
>
> I have read in some of the notes here on time-nuts that people may be able to use RS232 for communicating with the RFTG units.  But it was designed for RS422 and I would suggest you use RS422 for best results.  I use a little RS422-4S232 converter which has worked fine for me.
>
> The early units had FRS rubidiums in them.  The LPRO was used in the newer units.  So, you have the more recent design.
> Connected by DROID on Verizon Wireless
>
> -----Original message-----
> From: Peter Bell <bell.peter at gmail.com>
> To: Discussion of precise time and frequency measurement <time-nuts at febo.com>
> Sent: Sun, Oct 9, 2011 05:52:25 GMT+00:00
> Subject: Re: [time-nuts] Lucent RFTG-m-XO GPSDO
>
> On Sun, Oct 9, 2011 at 3:31 AM, k4cle at aol.com <k4cle at aol.com> wrote:
>> Peter, do you have the software for this unit?  The GPS antenna is supposed
>> to draw apx. 20 mA at 5 volts in order for the NO GPS LED to turn off.  AT&T
>> (Lucent) used the MicroPulse timing antenna (later sold and now provided by
>> PCTE).  You are correct in that Efratom used the Motorola UT+ 8 channel GPS
>> receiver on these units.  The rubidium companion box used the data from the
>> same receiver (via an interconnect cable between the two units).  Let me
>> know if you have questions on this unit, Regards, Doug....
>> Connected by DROID on Verizon Wireless
>>
>> -----Original message-----
>> From: Peter Bell <bell.peter at gmail.com>
>> To: time-nuts at febo.com
>> Sent: Fri, Oct 7, 2011 14:13:31 GMT+00:00
>> Subject: [time-nuts] Lucent RFTG-m-XO GPSDO
>>
>> I have been playing with one of these units, and noticed that there
>> has been some discussion on them before on this list, so I wondered if
>> anyone might have any suggestions.
>>
>> Basically, the unit powers up correctly, but the "No GPS" LED never
>> goes off - this obviously could be because it's broken or doesn't like
>> my antenna, but with some of these telecom GPSDOs you have to manually
>> trigger a site survey if you move them to another location. Does
>> anyone know if this Lucent box is like that?
>>
>> Everything else seems to be working - once the "OK" light comes on the
>> 15MHz output is enbled, the "No GPS" LED goes from solid to blinking
>> if you disconnect the antenna - it just doesn't want to get GPS lock.
>>
>> I suppose I could pull the Oncore board (a UT+ according to the label)
>> out of it and test that on it's own - but I thiought I would see if
>> maybe it's a known issue first.
>>
> Hi, Doug
>
> I don't have any documentation at all - just the actual box.  The
> antenna is one that originally came with a Furuno marine GPS, but the
> spec looks plausible (+5V @ 40mA, Internal L1 preamp with 26dB gain -
> and it has worked with several other GPS units without problems.
>
> I just pulled the oncore out, and connected it up outside the box -
> and it doesn't work.  It passes the self test with a response code of
> 0000 (or 8000 with the antenna disconnected / 4000 with a short on the
> antenna socket - so it seems the current consumption is OK) - but no
> matter how long you leave it it still says it's tracking 0 satellites,
> although it happiy generates status reports.
>
> I wonder if this UT+ version is expecially sensitive to the antenna?
> I remember that the oncore VP would work with pretty much anything you
> hooked up to it.  Of course, it's equally possible that the GPS module
> is defective.
>
> I'm tending towards broken - I also got an RTFG-m-RB with this unit,
> and that has a faulty LPRO-101 in it (it's probably fixable - it looks
> like the FET that heats up the Rb cell had gone open circuit) - and
> the two units together only cost me $40 supplied on a "status unkown,
> but likely defective" basis. I should get at least $40 of
> entertainment out of trying to fix them :)
>
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