Earlier i have written a blog about RTK, where i have used ublox modules for RTKlib. Ublox GPS(GNSS actually) modules are famous for their cost to performance ratio. Another reason is RAW code phase data from GNSS receivers, although they don’t support RAW output feature officially for their non-premium modules. Most of the opensource and commercial drones too started using ublox for low cost and better performance. This is the only GPS modules with Binary output in such low price range.
Now ublox modules are available every online electronics component supplier and amazon ebay flipkart too. But most of them seems to be fake.
- Module name written on enclosure is M8N but just over the TIN Casing something else M6 or M7(models with compass used for drones).
- Sometimes users peel of the sticker on the tin casing it shows a sticker/label with lower version M6 or M7
- The U-Center catch different name when queried for software and hardware version
- User complain about up-gradation failure
- Some users complain they are not getting Galileo Reception
- Some users fail to store the configurations they have changed
- Few people peeped whats under the tin case found few things missing
- Ublox M8 and M7 doesn’t support I2C memory but boards have I2C EEPROM
Well every case is different we will discuss every case,
M8Q or M8M as M8N
They have supplied a M8Q or M8M both are 30-40% cheaper than the M8N, they miss few things like 1.Low Noise amplifier, 2.Saw filter, 3.Flash Memory for multiple use(Firmware upgrade, configuration store..). They just change the sticker and sell it as a M8N. These are some times written as not upgradable as the firmware is in ROM. Here is one available at ublox m8n
M6/M7 stickers changed
its all M6( Neo-M6) they just change the sticker and sell it as M8N, they still perform good as they are atleast Neo-m6 or m7. User can easily find it through U-center application.
They used only the Core Chip M8030 from ublox
in this case they use it in several ways some vendors try to add up everything as in ublox M8N module. The flash memory, The SAW filter and the LNA on the module board. On board LNA is an extra for higher gain there is a LNA already inside the chip which obvious for GNSS Chips. Here is a link of such a module available at Self Assembled m8n. These modules will perform same as ublox original module iff components are good.
HolyBro Uses LNA Chip MAX2659ELT+ , no flash, no SAW filter
RadioLink uses LNA Chip MMIC BGA715L7 from infineon and Murrata SAW filter(only on SE100 no in TS100)
Radiolink modules seems cheaper than holybro modules and with additional features.
But this is not same for all cases. Most manufacturers just use the the core IC and other components except the flash memory LNA and SAW filter. These cases user cant detect through u-center because they put the original firmware. Sometimes it shows as the core chip only. Because of no LNA filter it can’t perform as good as the original module.
Modules with unnecessary chips and battery on board
For several reasons a memory chip is useless with M8N, and the battery too
- M8N has inbiult flash memory for firmware and config
- M8N doesn’t support I2C EEPROM as most of them use I2C AT24C512C EEPROM
- Battery was earlier used for battery backed RAM storage in M6 and M7 modules, now its stored in flash
there are more possible cases of fraud, if you are going to use it for drone(with a inbuilt compass) then beware of communication modes available. Some manufacturers even create a fake I2C adress for the Non HCM58 compass chip, they use AK97 chip instead.
How to detect a fake M8N module ?
Memory Chip(Exception SQI Flash) or battery on board means its fake
Where can i Buy a genuine ublox m8n module
- Directly from ublox, or try the
- holibro m8n module from banggood
- Here GPS( for indians purchase from indronesolutions they are certified distributer for proficnc products)
- Navio2 board for raspiberry pi