# Range by skydel

**URL:** <https://learn.safran-navigation-timing.com/t/range-by-skydel/725>\
**Category:** Skydel Discussion\
**Created:** [July 6, 2022, 10:22pm UTC](https://learn.safran-navigation-timing.com/t/range-by-skydel/725 "2022-07-06T22:22:59Z")\
**Posts on this page:** 5\
**Page:** 1

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**Author:** ![alqurask](https://avatars.discourse-cdn.com/v4/letter/a/9e8a1a/32.png) [@alqurask](https://learn.safran-navigation-timing.com/u/alqurask)\
**Post date:** [July 6, 2022, 10:22pm UTC](https://learn.safran-navigation-timing.com/t/range-by-skydel/725/1 "2022-07-06T22:22:59Z")

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Hello @Grace  
I just have one quick question.  
I generate simulator for known coordinate station (CORS station by NGS ) since we have observation file for the same date and time from NGS. I noticed the Range based on Pseudorange generated by simulator is too different compared with Range from NGS website for the same date , time and satellite. I attached couple of screenshot to be more clear. Do you have any idea why it is too far. Is doing simulation in NONE mode effect ?

I also compared Navigation file between two , Some Keplerian elements are too off

The CORS station is p375. Date:2022 1 1

If you could please take a look and give me your suggestion , I will really appreciate  
[Compariosn\_None.pdf](https://learn.safran-navigation-timing.com/uploads/short-url/yrj4MTFPhvBTNVrDzLaijvrTyWr.pdf) (509.0 KB)  
it

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<div class="post-metadata">

**Author:** ![Grace](https://avatars.discourse-cdn.com/v4/letter/g/f17d59/32.png) [@Grace](https://learn.safran-navigation-timing.com/u/Grace)\
**Post date:** [July 7, 2022, 12:59pm UTC](https://learn.safran-navigation-timing.com/t/range-by-skydel/725/2 "2022-07-07T12:59:03Z")

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Hi @alqurask,

We have received your question. We will check and get back to you as soon as possible.

Regards.

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**Author:** ![Grace](https://avatars.discourse-cdn.com/v4/letter/g/f17d59/32.png) [@Grace](https://learn.safran-navigation-timing.com/u/Grace)\
**Post date:** [July 8, 2022, 8:04pm UTC](https://learn.safran-navigation-timing.com/t/range-by-skydel/725/3 "2022-07-08T20:04:00Z")

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Hey @alqurask ,

Indeed, the Pseudorange of the Rinex observation files includes the real clock errors of the satellites in the PSR calculation.

In skydel, since the simulator defines the position and motion of the satellites by extrapolating the data from the Rinex ephemeris, we should expect errors in the PSR calculation as well.

So it is normal that you have an offset when comparing the two PSRs.

Regards

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**Author:** ![alqurask](https://avatars.discourse-cdn.com/v4/letter/a/9e8a1a/32.png) [@alqurask](https://learn.safran-navigation-timing.com/u/alqurask)\
**Post date:** [August 18, 2022, 1:46am UTC](https://learn.safran-navigation-timing.com/t/range-by-skydel/725/4 "2022-08-18T01:46:21Z")

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Hello @Geace,  
Just one more question related to that. Beside the fact of skydel simulator relies on RINEX ephemeris , Is there any other factor cause this difference such as clock error , … etc.

Best

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**Author:** ![Grace](https://avatars.discourse-cdn.com/v4/letter/g/f17d59/32.png) [@Grace](https://learn.safran-navigation-timing.com/u/Grace)\
**Post date:** [August 18, 2022, 5:28pm UTC](https://learn.safran-navigation-timing.com/t/range-by-skydel/725/5 "2022-08-18T17:28:28Z")

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Hi @Khalid,

Yes, the pseudorange calculation on the observation file is the distance from the receiver antenna to the satellite antenna, including receiver and satellite clock offsets, and other biases such as atmospheric delays.

Regards