[time-nuts] Practical considerations making a lab standard with an LTE lite

paul swed paulswedb at gmail.com
Tue Nov 25 03:36:13 UTC 2014


It won't respond the LTE LITE is send only.
I found another program from the Chip manufacturer and it behaves teh same
as expected and mentioned by Said.
So putty works as well as anything.

OK my first external fun with the LTE.
Since I had no 74AS74 I used a 74HC74 chip running at 4.5V. This allows it
to operate with the 3.3V logic and act as an intermediate to a 5 volt logic
family. The 4.5V is generated by a single diode drop with filter cap. I
used both sections of the 74 so that 10 MHz and 5 Mhz are available. Now to
do things like buffer and LPF the signals.

An interesting comment from Bob. He suggests just using a traditional
buffer logic chip then a LPF afterwords with a build out resistor to be
able to drive coax.
I may build that up using some buffers I have just to see how it works. I
am thinking TTL just to tinker. Bob suggested an interesting chip bot they
are SOT23 5 pin. Maybe I'll try that. But not at first.

Regards
Paul
WB8TSL



On Mon, Nov 24, 2014 at 9:39 PM, Jim Sanford <wb4gcs at wb4gcs.org> wrote:

> Said:
>
> I'm seeing C/No numbers between 50.0 and 41.0 for the "green" birds.  I'm
> seeing 27.0 to 42 on the "blue" birds.  Not quite sure what the difference
> between green and blue is.  UBlox is acting kind of funny -- it ignores any
> attempt to click on an icon or any of the menu bar items.  Yet it lets me
> move the various windows around and resize them.  A challenge for another
> day.  (Winders7)
>
> HDOP is 1.0, which wikipedia tells me is "ideal".  PDOP is 1.9, still
> good, but far from ideal.  Reported position is very stable, converting
> altitude (meters) to feet gets me 1158 feet, about 120 feet lower than what
> the GPS in the car says my antenna should be at.  (1250' at the drive way,
> plus 20 feet of pole supporting the antenna.)
>
> Jim
>
>
> On 11/24/2014 8:27 PM, Said Jackson wrote:
>
>> Jim,
>>
>> Bobs suggestion is good; look at for example the  LT3060 for something
>> that needs less than 100mA.
>>
>> Glad your antenna is working well. What C/No numbers is uBlox indicating?
>>
>> Bye,
>> Said
>>
>> Sent from my iPad
>>
>> On Nov 24, 2014, at 16:28, Bob Camp <kb8tq at n1k.org> wrote:
>>
>>  Hi
>>>
>>> The Linear LT1764 is a pretty good part. It’s nice and rugged / tough to
>>> kill. Bypass the output with a few hundred uF of tantalum caps. Keep at
>>> least a volt between input and output.
>>>
>>> Bob
>>>
>>>  On Nov 24, 2014, at 7:12 PM, Jim Sanford <wb4gcs at wb4gcs.org> wrote:
>>>>
>>>> Said:
>>>>
>>>> Several times you've mentioned a low noise LDO regulator.  I've not
>>>> seen a device specified -- can you share?
>>>>
>>>> Also, yesterday, in response to my question about using an existing
>>>> antenna, you basically said, "Try it."  Well, I did -- working great for
>>>> over 24 hours.  At this moment, I have good lock on 9 GPS birds and a
>>>> "3d/gps" fix mode reported by U-center.  Interestingly, there are a few GPS
>>>> birds that show up as blue, even though they have the same C/N ratio as
>>>> some green birds.  One of them is at 89 degrees elevation -- no blockage
>>>> like some to the west -- don't get that.
>>>>
>>>> Anyway, wanted to share that my existing antenna seems to be working
>>>> fine!
>>>>
>>>> AND, my first 10 MHZ board arrived today . . . .
>>>>
>>>> Thanks,
>>>> Jim
>>>> wb4gcs at amsat.org
>>>>
>>>>
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