[time-nuts] TrueTime AL-AK GPS receiver help

[Bob Camp]

Hi

If you want to dig into something like this to learn and to maybe fiddle with a 
downconverter design - sure, that’s a great thing to do. It’s a hobby and (hopefully) 
you are set up to handle the task. You probably are already a member of a list (or three)
where you have access to info on your project. 

Since we have zero info about the original requester, I am indeed guessing here. 
That can often be a bad thing to do. My *guess* is that this is somebody who
simply wants a working device. If so, there are a lot of bumps in the road that
they need to understand. If the answer is “I want a simple NTP server that is setup 
and forget”, this is probably not the way to go. 

Bob

> On May 1, 2015, at 9:55 PM, paul swed <paulswedb at gmail.com> wrote:
> 
> Bob brings up all the additional details that are the reality of dealing
> with teh older gear. Especially the date offsets because of the 1024 week
> cycle. That is a real pain.
> But the reason to spend time on something like this is to understand
> something and to learn.
> I picked up the austron 2000 gps because it was a useful rack mount box.
> Then realized some of its unique qualities. That was the driver for
> reviving it.
> I was lucky that I was able to obtain some operational data and then later
> schematics. BUT it was still a heck of a reverse engineering and adapting
> process.
> I am pretty sure I shared that on time-nuts and will guess that must be 5
> years ago now.
> Regards
> Paul
> WB8TSL
> 
> On Thu, Apr 30, 2015 at 5:58 PM, Bob Camp <kb8tq at n1k.org> wrote:
> 
>> Hi
>> 
>> I guess the first question would be:
>> 
>> Are we sure it’s an AL-AK and not an XL-AK?
>> 
>> Past that it becomes a fairly involved process of, is it worth real money
>> to get this up and running?
>> 
>> If we are talking about a $20 eBay find that is worth another $5 to have
>> somebody else get it running, the
>> conversation is a real short one.
>> 
>> If the AL-AK has some inherent value (it’s a working GPS disciplined Cs
>> maybe) then putting a few hundred
>> dollars into checking it out and getting it running might make sense. If
>> it’s like most of the parts from that
>> era, the delta between getting it checked and getting it running is pretty
>> small.
>> 
>> Once you *do* have it running, what do you have?
>> 
>> 1) Leap second problems
>> 2) GPS year rollover problems
>> 3) Tracking issues
>> 4) A noisy receiver with very few correlators
>> 5) Software support issues
>> 
>> This is an unusual box that is at least 20 years old. It *will* have at
>> least some of the listed issues and
>> may have all of them. Fixing them will be impossible.
>> 
>> ========
>> 
>> Why bring up all of the negatives? I for one have been sucked into this
>> kind of thing a *lot* of times
>> in the past. Just a few more this or that and it’ll be running fine. Much
>> better to figure out the likely
>> cost and outcome first. That’s *very* hard to do, and even harder to
>> follow through on. If you can’t
>> do the work yourself, the cost isn’t just lost time. This can cost real
>> cash.
>> 
>> Bob
>> 
>> 
>>> On Apr 30, 2015, at 12:50 PM, Tom Van Baak <tvb at LeapSecond.com> wrote:
>>> 
>>> I received this email. Anyone have a good answer?
>>> Thanks,
>>> /tvb
>>> 
>>> ----------
>>> Someone on ebay advised me to contact your website in hopes that someone
>> in your organization can help me with my TrueTime model AL-AK GPS Receiver.
>> I need to send it to someone so that they can check it to see if it works
>> and can track Satellites.  This receiver has the onboard up/down convertor
>> board that changes the receiver input frequency which is set at 4.092 MHz.
>> I don't have the needed down converter at the antenna. I bought this
>> receiver on ebay from someone who told me that he doesn't have the down
>> converter as well and can't figure out how to get it to work at 1575.42
>> MHz. He also didn't know if this receiver can be setup for a 1575.42 MHz by
>> removing the onboard converter and changing some DIP switches. If one of
>> your members can at least check out the receiver at 4.092 MHz for satellite
>> tracking That would be a big help ...
>>> ----------
>>> 
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