[time-nuts] Trimble Nortel GPSTM Boards
Bob Camp
lists at rtty.us
Fri Aug 2 09:24:45 EDT 2013
Hi
Either a blown receiver (likely the SAW filter) or antenna multi path.
Bob
On Aug 1, 2013, at 8:45 PM, Jim Sanford <wb4gcs at wb4gcs.org> wrote:
> I am seeing the same thing -- big jumps every single time a satellite is counted or not. Elevation mask 10 degrees, which should be very good and stable for my location. The unit also insists on converging to a bat altitude, then after a while declares stored position bad . .. then declares position good, even with bad altitude.
>
> Ideas appreciated.
>
> Jimwb4gcs at amsat.org
>
> On 8/1/2013 6:31 AM, Bob Camp wrote:
>> Hi
>>
>> You may have your elevation mask set to low for your antenna or a multi path issue from some other source. If the survey location is good to under a meter and the signals are good, there should be very little shift as sats are picked up or dropped.
>>
>> Bob
>>
>> On Aug 1, 2013, at 5:09 AM, GandalfG8 at aol.com wrote:
>>
>>> Hi Charles
>>>
>>> Thanks for your comments, the surveyed position on this is looking pretty
>>> good but what I have now realised is that the severity of the jumps seems
>>> very much related to the number of sattelites being tracked.
>>>
>>> Switching from 8 to 7, or 7 to 8, sats seems to produce the biggest step
>>> change whilst switching in either direction between 5 and 6, for example,
>>> doesn't seem to show up at all on the monitored DAC voltage.
>>> Ok, I take that back, it does still seem to depend on the number of sats
>>> being switched between but I've just seen a switch from 5 to 4 sats induce a
>>> very noticeable step change in DAC voltage, so the relationship doesn't
>>> appear to be linear.
>>>
>>> Unfortunately I need to power this down now for a few days but will
>>> investigate more later.
>>>
>>> Regards
>>>
>>> Nigel
>>> GM8PZR
>>>
>>>
>>> In a message dated 01/08/2013 09:45:24 GMT Daylight Time,
>>> charles_steinmetz at lavabit.com writes:
>>>
>>> Nigel wrote:
>>>
>>>> at times I'm seeing very noticeable step changes in the DAC voltage
>>>> on this one as that happens.
>>>> * * *
>>>> I am a bit surprised by the extent, a Mark Sims online plot from
>>>> 2012 shows some correlation on an NTGS50AA but not as noticeable as
>>>> this, and I don't recall seeing anything quite so pronounced on a
>>> Thunderbolt.
>>>
>>> IME (with TBolts), the magnitude of the DAC steps with constellation
>>> changes varies with the accuracy of the positional data used by the
>>> GPS. To a point, the more accurate the survey, the smaller the DAC
>>> jumps will be. (Other errors prevent reducing the
>>> constellation-change DAC steps to zero.)
>>>
>>> Mark has commented here on survey accuracy, and the methods he used
>>> in Lady Heather to maximize it.
>>>
>>> Best regards,
>>>
>>> Charles
>>>
>>>
>>>
>>>
>>> _______________________________________________
>>> time-nuts mailing list -- time-nuts at febo.com
>>> To unsubscribe, go to
>>> https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>>> and follow the instructions there.
>>>
>>> _______________________________________________
>>> time-nuts mailing list -- time-nuts at febo.com
>>> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>>> and follow the instructions there.
>> _______________________________________________
>> time-nuts mailing list -- time-nuts at febo.com
>> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
>> and follow the instructions there.
>>
>
> _______________________________________________
> time-nuts mailing list -- time-nuts at febo.com
> To unsubscribe, go to https://www.febo.com/cgi-bin/mailman/listinfo/time-nuts
> and follow the instructions there.
More information about the time-nuts
mailing list