[FOSS-GPS] Post-processing RINEX to simulate RTK

Sat Jun 30 03:26:27 PDT 2012

Dear Mauro

> How is turning out the comparison? how similar are both results for the
> same data?. It would be excellent that RTKLIB/RTKPOST could be validated
> with that level of data and experiments against those "well known top-level
> proffesional" (and very expensive) closed software suites, at least for
> some level of performance or for some defined applications.
>

Preliminary results look promising.

>
> Regarding the wireless testing, at our lab we have some "in the field"
> experience in data links on 400, 900 and 2400 Mhz (WiFi), so feel free to
> ask if you ever need some advice.
>

Thanks for your kind offer. I'm using Channel/Frequency: 36/5180 MHz and
channel width: 40 MHz; distances are around 1 km.

>
>  but when I got to face ambiguity resolution I just gave up....I'm hoping
> to find time again to dive THAT deep.....but now if the results are good
> enough to challenge commercial well known top level software-hardware, I'll
> be focusing on applications for it!
>

You "hit the target". I need to learn much more about cycle slips detection
and integer ambiguities resolution. I don´t want to dive deep into the
electronics concepts and electronic technical solutions of digital radio
telecommunications. After all I'm only a civil engineer, plain and simple.

We'll keep in touch.

Best regards

Antonio

>
> Best regards, thanks for that fast and complete answer, and good luck on
> your experiments.
>
>
>
> Mauro Ugarte A.
> Ingeniero de Desarrollo
> División de Instrumentación Óptica y Tecnologías de Teledetección
> Centro de Óptica y Fotónica
> Universidad de Concepción
> F/Fax: 2204740 | mauro.ugarte at cefop.udec.cl
>
>
> On 29/06/12 13:09, António Pestana wrote:
>
> Dear Mauro
>
>  Sorry from my very long silence.
>
>  I'm still testing the use of RTKLIB/RTKPOST to simulate "real-time"
> kinematic positioning in structural monitoring. I'm afraid my progress is
> still small.
>
>  We have done some experiments on the top of a 110 meters high viaduct
> pier. At the time of this experiment the top of the pier could move freely.
> I've collected 20 Hz GPS L1+L2 RINEX data both on top of the pier and at a
> reference site, 1200 meters away. The processing of the RINEX files was
> done mainly using "fix and hold" integer ambiguity resolution strategy.
> I´ve got some interesting results:
>
>  a) A East-West 24-hours cycle oscillation was detected; I suppose that
> it was due to the effect on the pier of the apparent diurnal movement of
> the sun.
> b) We were able to extract, from the displacements of the top pf the pier,
> the first natural frequency of the pier (around 0.5 Hz)
>
>  For the last three months I have been conducting experiments to compare
> RTKPOST processing of RINEX files with the RTK output of a very well known
> top-level professional software (made by a very well known company). At the
> same time I have been testing the use of wireless radio antenas to conect
> the sation sites to the reference site.
>
>  Apart from this experiments I'm still strugling with some theoretical
> concepts regarding GNSS positioning. It is still not clear to me the exact
> meaning of a number of terms that I find here and there. I suppose that
> there is still no uniformity in naming some key concepts of high-precision
> (centimeter or sub-centimeter) GNSS positioning. And I still need to truly
> learn the fundamentals of high-precision real time GNSS positioning, namely
> the distinct ambiguity processing strategies and the different positioning
> modes used.
>
>  Regards
>
>  Antonio
>
> 2012/6/29 Mauro Ugarte Avilés <mauro.ugarte at cefop.udec.cl>
>
>>  Dear Antonio,
>>
>> It's been a while since we talked about RTKLIB and all those networking
>> options.....how is it going?
>>
>> I would be glad to know something about your overall results, or some
>> partial results regarding the monitoring of structures you where
>> conducting.....I'm planning to learn a little bit of the absolute basics in
>> the civil engineering fields where precise positioning could apply,
>> particularly in the area of land surveying, in order to study possible
>> solutions to some of it's requirements trough the use of rtklib.
>>
>> (Any other list memeber's comments about some experience in this
>> particular application of precise positioning (RTK, PPP or even DGPS), are
>> really welcome.)
>>
>> Best regards!
>>
>>
>> Mauro Ugarte A.
>> Ingeniero de Desarrollo
>> División de Instrumentación Óptica y Tecnologías de Teledetección
>> Centro de Óptica y Fotónica
>> Universidad de Concepción
>> F/Fax: 2204740 | mauro.ugarte at cefop.udec.cl
>>
>>  On 26/10/11 19:05, António Pestana wrote:
>>
>>
>>
>> 2011/10/26 Mauro Ugarte Avilés <mauro.ugarte at cefop.udec.cl>
>>
>>>
>>>  Regarding that chapter, you should use as your network topology, the
>>> example 4 (Wifi) or 5 (mobile phone network), and replace on both of those
>>> examples the block "RTKNAVI" by Spider (and maybe move Spider to the "Base
>>> Station" or reference receiver's PC, and "STRSVR" to the remote receiver's
>>> PC) . If there is going to be line of sight between both locations, a
>>> Wireless Router or Access Point connected at the Base Station's PC Ethernet
>>> port (or wirelessly), an a USB wireless adapter with detachable antenna at
>>> the rover's PC (this one, for example:
>>> http://www.tp-link.com/en/products/details/?model=TL-WN722N), with both
>>> antennas (the AP/router and the USB adapter) replaced by a directional Wifi
>>> antenna like this one:
>>> http://www.tiendecita.com/antena-wifi-planar-estanca-marca-abaks-p-99.html,
>>> should do it. (Note that the antenna does not include the coaxial cable
>>> needed to connect the antenna to the AP/router (that by the way has to have
>>> a detachable antenna also, in order to replace it), but that cable can be
>>> easily found on computer stores). The USB wireless adapter used at the
>>> remote receiver's PC should be placed inside the box behind the antenna,
>>> were the RP-SMA connector is.
>>>
>>
>>  Once again very useful tips. Thanks.
>>
>>
>>>
>>>  My fault, no examples...but at least RTKLIB has a manual....and there
>>> are screen captures on it!! At the GNSS positioning techniques FOSS world,
>>> those features are not very usual... ;-).
>>>
>>
>>  Yes. I must agree with you. The manual is very good.
>>
>>
>>> Based on that brief descriptions, you would be able to find better
>>> explanations somewhere else: papers, doctorate theses, GNSS equipment
>>> manufacturers, etc.
>>>
>>
>>  That's what I'm trying to do these days...
>>
>>
>>
>>>  You will be sensing large structures, right? In that case, I would go
>>> with "static" (static rover, static reference), not "moving-base" (moving
>>> rover, moving reference) nor "fixed" (constant distance between rover and
>>> base). Maybe you could go with kinematic too, if the real-time
>>> displacements and deflections of the structures studied can be considered
>>> as "movement".
>>>
>>>
>>  My structures move at relatively high frequencies (say from 0,1 to 5
>> Hz). Most of the movements are small (a few centimeters at most).
>>
>>  Best regards
>>
>>  Antonio
>>
>>
>>
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