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Frequently and Infrequently Asked Questions

The iG4 (released October 2019) is the fourth generation of the popular iG3s, X900S-OPUS and X90D-OPUS receivers which were first released in June 2013 by iGage.

The iG4 tracks more satellites (GPS + GLONASS + Galileo + BeiDou) with a huge channel count. Complete differences are listed [ here ].

0. The price seems too low, is it too good to be true? This is the #1 comment from callers inquiring about static receivers from iGage. Please be assured that these receivers 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, well anchored, the phase center tolerances are tight and extremely well matched between devices and the Lithium-Ion batteries are top of the line. With 4-gigabytes of flash memory, you can keep months worth of observations on the device.

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 (iGage) write and maintain the software tools and provides fantastic service and support. The iG4, like its predecessors is the 'Real-Deal.'

1. How long will the iG4 run on a battery? A new battery at 70 deg F. will typically last 6 hours and 30 minutes. We supply 3,400 mAH batteries. A wide range of aftermarket batteries are available. Typically 3rd-party batteries are advertised as 2,200 mAH batteries and will power the iG4 for around 4 hours.

An external battery clip cable is included in each kit for attaching the receiver to an external 12-volt battery. We also have optional heavy-duty cables available.

For applications with line 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 (however we recommend that you still use one) 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 5 hours to charge a battery. You can charge four batteries at once with the supplied charger.

3. How much memory do these receivers have? 4-gigabytes. When the download tool copies a file from the receiver, it leaves the original on the receiver with a '_' pre-pended on the filename.

With typical satellite counts (22-300 the iG4 generates approximately 1.75 megabytes per hour.

The internal memory is large enough to store 90 days (24-hours / day) of 5-second interval data.

4. Has the antennas been calibrated by the NGS? Yes. The antenna is also listed in the OPUS dropdown box. Calibration files may be found [ here ].

5. Can the iG4 be used as a RTK receiver? The iG4 does have Bluetooth and it is possible to configure it to be a RTK Base, sending corrections out the serial port.

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 would be relatively difficult to configure with an external Serial to Ethernet adapter. Checkout our [ network purposed ] receivers 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 iGx-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? OPUS initially decimates submitted data to 30-second intervals, so there is no reason to submit higher rate data. We ZIP the submitted files to shorten the upload time.

For alternative services and RINEX files exported with the 'Export' button, the tool exports full rate data files.

9. Does the iGx Download tool support OPUS-Projects? Yes. See page 34 in the User Manual.

10. Would the iG4 GNSS receiver be a good choice for a large highway control project?  Yes.

The iG4 receiver is a fraction of the price of alternative devices. Given the same hardware budget, you could purchase three to 8 times more iG4 receivers than you could using repurposed RTK heads. More receivers allows densifying a control network with fewer sessions.

11. The batteries look familiar, can I use another source?  There are also several third party replacements available on Amazon and eBay that may work, search for 'Trimble 5800 Battery'.

You will find that our batteries are the highest quality Lithium-Ion batteries available and the 3,400 mAH capacity is higher than most alternatives.

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 Lithium-Ion 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.

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

12. L2C? Yes. L5? Yes.

432-channels, 4-constellations, 5-hz rate, tracking:
GPS: L1, L2, L2C
BeiDou: B1, B2, B3
Galileo E1, E5a, E5b

3.02 RINEX output files have these observables:

G 12 C1C C2P C5I L1C L2P L5I S1C S2P S5I D1C D2P D5I SYS / # / OBS TYPES
E 12 C1X C5X C7X L1X L5X L7X S1X S5X S7X D1X D5X D7X SYS / # / OBS TYPES

Sample output files are available [ here ].

13. What is the difference between a iG4 and other receivers?

In a nutshell: Price, download simplicity and performance.

It depends on the specific GNSS model that you are comparing to. 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 "+'. There is a huge variety of GNSS engines available in the same case.

14. Who does warranty and non-warranty service on these receivers? iGage Mapping Corporation in Salt Lake City provides service on the iG4 receivers. The receivers are warranted for 2-years, accessories for 1-year and batteries for 90-days.

15. Is the iG4 a good solution for aerial survey applications? Yes. Unless your application requires recording faster than 5 Hz. The internal GNSS boards are enabled for 20 Hz recording, however there may be issues recording at this rate with low elevation masks due to the higher data rate.

16. What is the maximum recording rate for static observations? The iG4 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 Stedi-Rest with every receiver: [ Click Here ]

18. What kind of data tests are performed by the iGx-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.)

In addition you can trim the beginning or end of any occupation.

We have 'built-in' functions so you can share your screen with our support staff and you can submit entire 'problem' jobs with all meta-data to us for us to look at.

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 iG4 track L5? Yes, see question 12 above.

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 sessions are 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 has elapsed. A new occupation file is NOT automatically opened. If you want to record data for an extended time, call us for help.

23. How long will the iG4 run on an external battery? The iG4 draws 0.3 Amps from an external 12 volt source. As the terminal voltage of the external source drops, the current draw will increase. The iG4 will revert to the internal battery when the external voltage falls below ~8 volts.

24. If the receiver is set to 30-second epochs, how long will it store data before the internal memory fills?  It depends on the recording rate, elevation mask and number of satellites that are tracked. For 5 hz, 0 deg mask and 22 to 30 SVs 1,750,000 bytes per hour are typically generated.

4 GB / (1.75 meg / hour * ( 5 second / 30 seconds ) ) = 13,700 hours = 570 days

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 iG4 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. We strongly recommend that you always have a internal battery in the head because the antenna is calibrated with a battery in the receiver.

27. What kind of RINEX file is exported? 2.11 by default. You can manually generate other RINEX versions. Samples are available [ here ].

28. What about 'Elevation Mask'? The iG4, 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.) 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 and locked.

It is possible to change the minimum value using the 'Receiver Settings' area of the 'GPS Settings' tab in the download tool via the serial port.

29. Did I read that the iG4 receivers write a RINEX file as the onboard data storage? The iG4 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 9,357,164 byte '.HCN' file is 28,944,578 bytes when converted to RINEX (32% of original size).

  • This format is engine neutral, 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. I would like to purchase a campaign set of receivers? Great! However we no longer offer prebuilt campaign kits. We think that you are better off having 6 separate cases than one huge coffin sized case. Plus, they cost less too.

31. What about REALLY long occupations? Will the iG4 record data for multiple days? Yes, see question 24, call us for additional information.

32. My Yellow and Green LED's flash simultaneously and the receiver won't store data files. Whoops, you allowed the battery to run down while the device was attached to a computer. Instructions for checking the flash drive and reformatting it are in the User Manual page 51. (Or just call us and we can help you out remotely.)

33. What are the differences between the X90D-OPUS (original static receiver) and the iG4? Here is a list with explanations:

iG4 tracks 384 channels instead of 24, more is better of course
iG4 is smaller and lighter weight
iG4 has Bluetooth and works as an RTK Base
iG4 tracks GLONASS, Galileo and BeiDou, this helps the receiver continue to track under heavy canopy
iG4 comes in a smaller hard case, easier to pack, costs a little less to ship
iG4 charger holds 4 batteries instead of 2
iG4 battery is qty 1 3,400 mAh instead qty 2 2,200 mAh (we only ship one battery standard now)
iG4 runs longer on the new battery than the X90 ran, however the iG4 does use more power
New 3,400 mAh batteries are $120 instead of $90 for 2,200 mAh
iG4 battery is shipped discharged and inside the head (because of new shipping regulations)
iG4 MSRP costs $2,400 instead of X90-OPUS $2,450 MSRP (however the street price is probably more)
iG4 includes Ground UPS shipping instead of 3-Day Select (required because of new shipping regulations)
The new optional 2-meter heavy duty cable is only $100 instead of $146

34. Why are there blue and red 'iG4' stickers on the side of the receiver? When you take a side view picture of the receiver over a mark there will be a distinguishing feature that identifies the correct antenna model. The stickers make it clear that this is a iG4 and not a X900U-OPUS, X900+ or one of the other similar devices.

34. If I want to manually process the observation files, what tool should I use? You can use any tool that has the 'iG4' antenna model and accepts standard RINEX files. Some tools won't have the iG4 antenna model, but might have the iG3s model which is nearly identical. CGO2 from CHCNave is a great, inexpensive tool that is purpose made for the iG4. You should use our download tool to download and convert the native files to standard RINEX.


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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