[FOSS-GPS] Amateur NTRIP casters

Mon May 12 18:23:18 PDT 2014

Software wise, I'm using custom software to 1) read from the U-blox receiver, and 2) generate RTCM 3.1 messages. I'm also interfacing to the new Skytraq receivers. The caster is event driven and makes use of the linux epoll() interface to efficiently manage tcp connections. The footprint per connection is very small, allowing a small computer to manage a large number of connections. Originally, I was targeting Ubiquity's router station pro, but the Raspberry pi is cheap and more than fast enough.

I agree power isn't an issue. It's more a matter of knowing what's available and planning for it. In my case, I'd like to be able to support 20 to 100 stations, so the hardware must be easy to assemble and  very reliable. I greatly prefer to not have to do any soldering. I'm expecting to use traditional (IEEE) POE powered from 110V, but many remote solar installations are based on 24V. I don't have a "solder free" solution for 24V, but I don't think there will be a problem finding one.

Rtklib would be one possible consumer of the data. Commercial systems (eg. Trimble) can also use it directly. Of course, I have my own plans to create a service which, combined with a smart phone and an external raw receiver, would generate accurate positions in "semi real time".

John Morris

Menlo Park, CA

________________________________
From: foss-gps-bounces at lists.osgeo.org <foss-gps-bounces at lists.osgeo.org> on behalf of Danny Miller <dannym at austin.rr.com>
Sent: Monday, May 12, 2014 3:48 PM
To: Open Source GPS-related discussion and support
Subject: Re: [FOSS-GPS] Amateur NTRIP casters

Plenty of very cheap buck converters to get 5V from higher voltage DC sources.  I don't think power is a problem.

What is this composed of?  Does RTKLib allow you to output data as an NTRIP caster?

Is there any kind of database your GPS could look up against its location and select it?  Or would you just need to know the IP# as an ad-hoc lookup?

Danny

On 5/12/2014 5:22 PM, John Morris wrote:
The basic requirements for a base station are 1) a good location, 2) reliable power and 3) reliable networking.  I suspect ham relay towers are in excellent locations and they have solved the power issues. They probably don't have great networking bandwidth. You could handle a limited number of connections on a local caster, but the main "hub" caster should have a high bandwidth connection and probably reside somewhere back in town.

My rPI fits into a weatherproof box and is powered over the ethernet cable (POE).  I'm using a Trmble compact dome antenna mounted on a 3/4" pipe. Rather than placing the antenna on a tall, wiggling tower, I'm hammering the pipe deep into the ground. The earth is a much more stable platform for precise positioning.

I'm not sure what voltages are available in the ham towers. The rPi needs a clean 5V.   I'm using a remote POE adapter over a 100m ethernet cable.  If you have 110Vac or 12V nearby, you could use a simple USB charger instead.

John Morris
Menlo Park, CA

________________________________________
From: foss-gps-bounces at lists.osgeo.org<mailto:foss-gps-bounces at lists.osgeo.org> <foss-gps-bounces at lists.osgeo.org><mailto:foss-gps-bounces at lists.osgeo.org> on behalf of John Morris <john at coyotebush.net><mailto:john at coyotebush.net>
Sent: Monday, May 12, 2014 11:17 AM
To: Open Source GPS-related discussion and support
Subject: Re: [FOSS-GPS] Amateur NTRIP casters

I'm setting up a small ntrip caster which runs on a RaspberryPi. It takes data from an Lea-Xt and  can broadcast both raw and RTCM 3.1 messages.  It doesn't support all the variations of Ntrip - just Ntrip 2 over tcp with simple password protection - but that is all I need for my purposes.

Over all, I'd like to set up a series of local, community base stations, and then do a mobile app for short static positions. I haven't started the mobile app yet, but the base station software is close to being usable.

I'd be interested in collaborating.

John Morris

Menlo Park, CA

________________________________________
From: foss-gps-bounces at lists.osgeo.org<mailto:foss-gps-bounces at lists.osgeo.org> <foss-gps-bounces at lists.osgeo.org><mailto:foss-gps-bounces at lists.osgeo.org> on behalf of Danny Miller <dannym at austin.rr.com><mailto:dannym at austin.rr.com>
Sent: Thursday, May 08, 2014 1:25 PM
To: foss-gps at lists.osgeo.org<mailto:foss-gps at lists.osgeo.org>
Subject: [FOSS-GPS] Amateur NTRIP casters

I have seen some things about NTRIP casters as references.  They're
supposed to be useful, but few and far between.  Long-distance baselines
are likely.

I was talking to a local ham radio group the other day, which was into
setting up stations... repeaters I think, as a grassroots public
service.  I think there was some sort of internet connection involved there.

Would it be useful to use something like LEA-6T or NV08-C L1 stuff as an
amateur, but more likely to be local (low baseline), NTRIP caster?

It really doesn't seem difficult to add this functionality to the sort
of physical stations they do.  Is it useful for accuracy?  Is there an
existing framework by which amateur, local NTRIP data could be located
and accessed?

Danny

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