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 X90 and X900S OPUS Frequently and Infrequently Asked Questions

Additional Information: [ Application Notes ]

0. The price seems too low, is it too good to be true? This is the #1 comment from callers inquiring about the X90-OPUS and X900S-OPUS. Please be assured that these receivers are not cheap. They are extremely well built. The accessories are first class and the hard-shell carry case and foam insert will protect your receiver for years of hard service. The GPS engine is top notch, the ground plane antenna is large, extremely good, well anchored, the phase center tolerances are tight and extremely well matched between devices. With 4-gigabytes of flash memory, you will probably never need to even delete your old jobs.

These receivers are built specifically for iGage by one of the largest (and we think the best) GPS manufacturers in the world. We designed it to exactly fill the requirements for static processing with no extras. We wrote and maintain the software tools. Most importantly we don't have a big operation with lots of sales and marketing people.

The X90-OPUS  and the X900S-OPUS are the 'Real-Deal.'

1. How long will the X90 run on a battery? A new battery at 70 deg F. will typically last:

X90-OPUS 6 hours
X900S-OPUS 7 hours

An external battery clip cable is included in each kit for attaching the receiver to an external 12-volt battery. For applications with 120-240 VAC power available, the power supply for the battery charger will also power the head. (And the external power clips will power the battery charger for charging cells at a remote location.) An internal battery is not required if external power is provided.

2. How long does it take the supplied charger to recharge a battery? From empty to full charge it typically takes 3 hours and 15 minutes to charge a battery. You can charge two batteries at once with the supplied charger.

3. How much memory do these receivers have? 4-gigabytes. It is so much memory that when the download tool copies a file from the receiver, it leaves the original on the receiver with a '_' pre-pended on the filename. We anticipate that the receiver can be used for backup storage of downloaded files for the life of the receiver without it ever filling.

4. Has the antennas been calibrated by the NGS? Yes, check out these links: [ ANTEX ] [ ANTINFO ] [ General ]

5. Can the X90-OPUS be used as a RTK receiver? The X90 is US satellite only, does not have Bluetooth, does not have an internal UHF radio. So it is not an appropriate receiver for RTK use. Check out the similar receivers [ here ]. That said, the X90 can be used as an 'Auto Base', details are available [ here ].

RTK operation on the X900S-receiver is not supported.

6. Can this receiver be used as a source of network real-time corrections? It is not a great choice: it does not have an Ethernet port, it does not track GLONASS, it would be relatively difficult to configure. Checkout the CHC N71 receiver for an inexpensive, perfect solution for this application.

7. Why do you have to paste (Control-V) then press enter to fill in the ZIP filename when submitting to OPUS? The Internet Explorer has a reasonable security precaution that will not allow a program to automatically upload a file from your computer to the internet. If the X9x-Download tool could automate this step, then a malicious program could steal your address book, or any file, from your computer.

8. Why does the download program decimate and ZIP observation data? Consider a 5-second interval, 2-hour observation file: a typical size is 1,620,000 bytes. 15-second decimating reduces the file size to 550,000 bytes. The ZIP'ed file is 190,000 bytes. So the upload time (the time it takes your computer to upload the file to NGS is reduced 88%.) If you are connected by MiFi or CellPhone while in the field, this might save you considerable time.

9. Does the X9x-OPUS download tool support OPUS-Projects? Yes.

Here is how it works:

a. On the 'Configuration' tab set 'Show Advanced Settings' to 'Support OPUS-Projects':
b. Now under the 'Project' selector, check the (now visible) 'OPUS-Project' checkbox:
c. Finally, when you click on 'Prepare for OPUS', the download tool will automatically push the 'OPTIONS' button on the NGS submittal form and enter the project name:

10. Would the X90-OPUS GPS receiver be a good choice for a large highway control project?  If you are going to process using NGS OPUS or NGS OPUS Projects; an unqualified yes.

If you are planning on processing and adjusting the results yourself using TBC, SPSO, GNSS Solutions or another tool; perhaps:

A more expensive receiver will allow you to use GLONASS observables, which will shorten your observation times. But it will introduce uncertainty due to inter-channel bias on the GLONASS observables unless every receiver is exactly the same.

Clearly given the same hardware budget, you could purchase three to 10 times more X90-receivers than you could using repurposed RTK heads. More receivers is probably much-more-better in this case. A fleet of 20 X90-OPUS static receivers will probably beat a set of 5 GLONASS receivers.

The X900S-OPUS receiver costs only a bit more and tracks GPS+GLO+BDS constellations and is an excellent choice at a very reasonable price.

11. The batteries look familiar, can I use another source? Leica GNSS batteries fit and work, however they have a third terminal that is not used on the X90-OPUS receiver or charger. Trimble batteries also will run the X90-OPUS. There are also several third party replacements available on Amazon and eBay that may work.

You are cautioned to ONLY only charge CHC batteries in the CHC charger and to not charge alternate batteries in the CHC charger. Intermixing charging technologies (for example charging CHC batteries in Leica chargers) is asking for a meltdown and possible fire.

In other words "All of the 7 volt batteries that fit in the hole, probably work well" but we are not responsible for issues and mishaps that occur with batteries that we don't sell. That said, we have no knowledge of any mishaps.

If you want to search Amazon for batteries, try this link [ Compatible Batteries on Amazon ]

12. L2C? X90-OPUS->Yes! Checkout Don Jewell's excellent article [ here ]. Who cares? You may in 2020. Checkout [ phase-out ].

13. What is the difference between a X90-OPUS and a standard CHC X90? It depends on the specific X90 model, X90's have been introduced in several variants. Here are the possibilities: Bluetooth or No Bluetooth; UHF Radio or no UHF Radio; Cell Data Modem (three models) or no Cell Data Modem; 32 Megabyte flash or 4 GB flash; USB Flash drive interface or RS232 Serial Interface; GPS or GNSS; "+" or no "+'. Suffice it to say that the X90-OPUS is a stripped down X90; just what you need for NGS OPUS-Static, OPUS-RS, OPUS-Projects and not much more.

Also note that the iGage X90-Download tool, by design, only works with receivers that originate as X90-OPUS receivers. So a X90 variant purchased in Hong Kong, won't work with the iGage download tool.

What is the difference between a X900S-OPUS and a standard CHC X900+? It depends on the specific X900+ model. Here are the possibilities: Bluetooth or No Bluetooth; UHF Radio or no UHF Radio; Cell Data Modem (three models) or no Cell Data Modem; 32 Megabyte flash or 4 GB flash; USB Flash drive interface or RS232 Serial Interface; GPS or GNSS; "+" or no "+'. Suffice it to say that the X900S-OPUS is a stripped down X900+; just what you need for NGS OPUS-Static, OPUS-RS, OPUS-Projects and other static campaigns.

Also note that the iGage X90-Download tool, by design, only works with receivers that originate from iGage. So a X90 variant purchased in Hong Kong, won't work with the iGage download tool.


14. Who does warranty and non-warranty service on these receivers? iGage Mapping Corporation is the responsible party. While CHC maintains an excellent factory repair depot in the United States for all other products, we take care of the X9x-OPUS receivers at our office in Salt Lake City Utah.

15. Is the X90-OPUS a good solution for aerial survey applications? Probably, see the GLONASS note on Question 10. Again, the low price allows you to purchase lots more receivers to strengthen your network solutions.

The receivers support higher rate recording intervals, if needed for inertial post-processing software:

16. What is the maximum recording rate for static observations? The X90-OPUS will record 5-Hz (5 observations per second, 0.200 second spacing.) 16B. Are higher data rates (faster than 5Hz) possible? Please call us.

17. What about a Tripod? Fixed height tripods are best. We include a Hold-A-Pole with every receiver: [ Click Here ]

18. What kind of data tests are performed by the X90 download tool?

  • Observation files shorter than the programmed length (7,000 bytes by default) are outright ignored.
  • Observation files without navigation messages are flagged and transferred to the hidden "_Error" project.
  • Observation and navigation files are checked for minimum RINEX structure requirements.
  • MP1 and MP2 are monitored for gross problems, although only severe issues are flagged.
  • Warnings are generated if the proper antenna model, HI or email can not be automatically filled on the OPUS submission form. (As opposed to just continuing with a default antenna model.)
  • Email addresses are checked to insure reasonable form.
  • Occupations are automatically classified as suitable for OPUS-RS or OPUS-Static.
  • Occupations longer than 48-hours are rejected.
  • Occupations shorter than 15-minutes are rejected.
  • Occupations that ended after the top of the current hour are flagged as probably having no overlapping CORS data (yet.)
  • For the first 15-minutes of each hour, occupations that ended in the previous hour are flagged as probably having no overlapping CORS data (yet.)

19. When I enter "2" meters for an HI, the download tool displays "2.000,0"; what's up with that? The download tool is inserting a comma to make it easier for you to discern 1/10th millimeters:

Which is easier to read?  4743107.431  or  4,743,107.431

Same difference:  2.1315 or 2.131,5

20. Does the X90-OPUS track L5? No. Other, more expensive receivers do. Give us a call and we can hook you up. The point of the X90-OPUS is to have the minimum specifications and price while still providing access to NGS OPUS (Static, Rapid Static and Projects.) In a couple of years OPUS will probably accept L5 and GLONASS. At that time, it will make sense to make an entry level receiver that tracks L5 and GLONASS. But for now, the X90-OPUS is what we need for OPUS; and nothing extra.

21. Can you download files from the receiver while it is recording data? No. When you connect the USB plug, the receiver stops recording data and emulates a thumb drive.

22. When sessioning is enabled, do the sessions start at the top of the hour or 1-hour after the file is opened?  Sessioning happens after the programmed time.

23. Have you ever tested the X90-OPUS to see how long they will run on a 50 amp hour marine battery? At 12.3 V the receiver draws 0.028 amps. 50 AH / 0.028 A = 1,785 hours = 74 days which is over 2-months.

24. If the receiver is set to 15-second epochs, how long will it store data before the internal memory fills?  The receiver generates about 1 megabyte of data for every 80 hours of occupation at 15-second epochs while tracking 12 SV's. The receiver holds 4-GB. That is 320,000 hours or 13,300 days or 444 months or 35 years. Obviously this is derived, not tested.

25. What happens if the battery runs out during an occupation? If the battery runs out, or the battery is removed while the receiver is storing data, the file is left intact in memory. No epochs are lost. This has been extensively tested.

26. What happens if external power is attached? The X90-OPUS will run off of external power until external power is removed and then switch to the internal battery. The internal battery is not charged by the external power source. It is not necessary to have an internal battery if external power is supplied, however it does provide a back up in case external power is lost.

27. What kind of RINEX file is exported? 2.10. Here is a sample observation header:

28. What about 'Elevation Mask'? The X90-OPUS, by default, is set to record satellites above 0 (zero) degrees. OPUS ignores observations below 10 degrees (this used to be 15 degrees however it was changed to 10 degrees.) Since the X90-OPUS has essentially unlimited internal memory available to store observation data, we want the engine to begin tracking SV's as soon as they are visible so that as they rise to 10 degrees they are fully tracked.

If you disagree with tracking to zero degrees, it is possible to change the minimum value using the 'Receiver Settings' area of the 'GPS Settings' tab in the download tool:

29. Did I read that the X90-OPUS receivers write a RINEX file as the onboard data storage? The X90-OPUS stores occupation data in a proprietary file format with the extension '.HCN' in the flash memory inside the receiver.

The download tool automatically convert the HCN file to standard RINEX (see FAQ #27) when the file is downloaded from the receiver.

Here are some good reasons to like the '.HCN' file format:

The HCN file is compressed. A 111,000 byte '.HCN' file is 317,000 bytes when converted to RINEX.

This format is engine neutral (so we can change out the internal GPS engine to an alternate brand or model and still write out '.HCN' files and use the same conversion tool to generate standard RINEX data.

30. Will the X90-OPUS work in the Canadian Spatial Reference System Precise Point Positioning  post-processing application? Yes, CACS has the X90-OPUS antenna model and will correctly process observation files from the X90-OPUS. See [ CACS PPP ] for information on this system. Because of CACS's site web scripting, the download tool is unable to automate the process of submission, however CACS has a great [ PPP Direct ] desktop application which allows you to directly drag and drop X90-OPUS observation files into CACS.

31. Will the X90-OPUS work in AUSPOS? (See [ AUSPOS ] for system information.) Yes, AUSPOS includes the X90-OPUS antenna model and will properly compute heights. Builds 9100 and higher of the X90 Download tool will automatically submit your observations to AUSPOS.

32. Can the X90-OPUS be used with 'RTX CenterPoint'? Yes, the X90 Download tool includes a button to automatically submit observation files to RTX. Because RTX only accepts observations from a subset of devices, the download tool spoofs a supported receiver (with the same engine), spoofs a supported antenna and adjusts your HI to compensate for the L1 phase center offset difference.

34. Is the X90-OPUS listed in the IGS antenna and device files? Yes:
The X90-OPUS is defined in the IGS Antenna Working Group's [ antenna.gra file ]
  The X90-OPUS receiver and antenna are defined in the IGS [ Equipment Description file ]

35. Can the X90-OPUS be used with Trimble Business Center (TBC) and Spectra Precision Survey Office (SPSO)? Yes, once files are downloaded from the receiver, they are standard RINEX files.

36. Will the X90-OPUS work in Gamit-Globk? (See [ GAMIT-GLOBK ] for system information.) The X90-OPUS receiver antenna definitions are not available in the rcvant.dat file (yet.)

37. I would like to purchase a campaign set of receivers? Great! We have a [ standard configuration ] with 6 receivers and 6 chargers in a (albeit large) case with plenty of room for accessories. The outside case size is 44.9 x 25.32 x 16.5" (114 x 64.3 x 41.9 cm) Complete kits are reasonably priced.

38. What about REALLY long occupations? Will the X90-OPUS record data for multiple days? Checkout [ X90-OPUS-DealingWithGIANTFiles.pdf ]

39. My Yellow and Green LED's flash simultaneously and the receiver won't store data files. [ Read This ]


Note: Trimble Business Center (TBC) and Spectra Precision Survey Office (SPSO) are trademarks of Trimble Navigation.

iGage Mapping Corporation
1545 South 1100 East STE 1
Salt Lake City UT 84105 USA

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