DGPS on Garmin GPSMAP 64 using NTRIP on Android device?

[vgurra]

Recently the ordnance of survey in my country set up a free service providing differenctial corrections over internet (NTRIP).

Sounds like great news to me since I am using my GPS mostly under forest canopies that does cut out the SBAS (WAAS/EGNOS) corrections most of the time.

With really good differential corrections over NTRIP I hope to be able to get consistent sub 1m accuracy even in the forrest.

Setting this up should in theory consist of getting a USB to serial cable (that Garmin sells) and then connect that to a serial to bluetooth adapter that can communicate with the NTRIP service on my Android smartphone.

I already got the Lefbure NTRIP client working properly on my smartphone. What is left is the "plumbing" (to connect Garmin USB->Serial->Bluetooth->NTRIP on Smartphone)

Is there anyone that has done this exercise and got it working? Do & donts?

Any other suggestions on how to achieve consistent sub 1m accuracy at a comparable cost to the setup above (other device than gpsmap 64)?

Brgs,
Vgurra

 

[Nuvi-Nebie]

I'm wondering if you could cut down the number of interface conversions by using an Android microUSB to standard USB hub (OTG) (LINK HERE) or an Android microUSB to Serial (RS232) (LINK HERE) or maybe

 

[vgurra]

The "StarTech.com Micro USB to RS232 Serial Adapter Cable for Android" is one of the two parts needed as I outlined the communication chain. Garmin sells a similar product. But there needs to be something in the serial end also. Something like this:

http://www.aliexpress.com/item/RS23..._1&btsid=3bf3b212-fbf5-4c3c-9dd6-5d23ed9d89d0

There are other adapters as well but this one contains a chargeable battery. My understandning is that the GPSMAP USB will not provide the current needed to drive an adapter without a battery.

 

[Nuvi-Nebie]

The suggestions above were to try to get around the Bluetooth step, Both the GPS and the Android smart phone are USB devices, so I though it may be possible to remove the Serial (RS232) step as well, by using the first option above and going :-
Android Micro USB . . . USB Micro to USB hub . . USBcable to the GPS
rather than :-
Android Bluetooth . . . Bluetooth to Serial . . . Serial to USB . . . GPS USB connector

But maybe the NTRIP software running on the Android device has to operate over Bluetooth? if so, it would be nice to simply connect the GPS USB socket to a USB to Bluetooth dongle, however it is very unlikely that the GPS will be able to drive the dondle

 

[vgurra]

My understanding is that the Lefebure NTRIP app on Android seems to be bluetooth (serial data profile) only. On PC (wich I will not use in field) there has to be a virtual com port (serial communication).

 

[Nuvi-Nebie]

I can't see why the Android App. uses GPS coordinates from an external device, when android devices have built-in GPS ! ! !, here is a comment from their own site :-

 

[vgurra]

The primary purpose of the NTRIP app is to provide an external GPS receiver with differential corrections in RTCM format.
It can also receive NMEA data from the GPS receiver. This can be used in two ways. 1) To assist selecting the best data stream from the NTRIP service 2) To let DGPS coordinates replace coordinates from the Android in any app. Means that you can get high accuracy in any app on the Android if you prefer that instead of the GPSmap functionality.

However it seems like the GPSMap 64 cannot send NMEA while receiving RTCM. Earlier models had options for "RTCM in/NMEA out" but hte 64 only seem to have a "RTCM" option.