Apologies if this has been asked before. I'm looking into building my own RTK base station (perhaps with an ArduSimple or the like), but I'm not sure how it'd stack up against properly installed professional RTK base stations that cost £10k. Are "home made" RTK base stations less reliable? How come the difference in cost is so huge?
DIY RTK base station
- Thread starter pokmo
- Start date
- Location
- Shropshire
I've been pondering on doing the same, ArduSimple apparently are bringing out a new product in about 3 or 4 months time that can be used as a base station and will out put 1007 and 1008 messages which I understand Topcon receivers need.
Emlid Reach are also considering adding these messages as well but when who knows?
Emlid Reach are also considering adding these messages as well but when who knows?
Northern farmer
Member
- Location
- North
Many simple (low cost) options to add those missing messages for Topcon, Trimble etc. Emlid Reach is using the same u-blox receiver as the low cost Ardusimple products. A lot of unexplained cost in their product too although they have features that Ardusimple do not have.
The big names are not going to explain what is so much better on their products but I would have expected more detailed comparison from u-blox or those companies who build their products using u-blox F9P or similar receivers.
I believe one significant difference is the actual antenna. On the expensive receivers the antenna is some mechanical artwork. Needs to receive all frequencies at all angles at accurate phase difference etc.
The u-blox F9P performance is pretty close to that of the expensive receivers. Dual frequency support, multiple constellation support. Not so old commercial receivers were still limited to GPS + Glonass while F9P handles Galileo and Beidou too (like the expensive receivers do today).
There are some missing pieces with F9P that are difficult to understand for most of us farmers. One example is the GPS L2 signal support. F9P only supports the modernised GPS signal while the expensive ones make use of the older format too. Don't know the exact number of GPS birds that have not been upgraded but someone recently mentioned and order of 30%. Someone at this forum talked about another "missing code" issue but I could not find that discussion just now. That one was even more difficult to understand because RTK correction signal should be about the carrier phase between different birds and for different frequencies and I don't understand why any difference if the base receiver measures this from one code or another (assuming similar time resolution for both).
Obviously the accuracy of the local clock makes a difference and the more expensive (less integrated) products may have a significantly lower noise reference clock. The receiver sensitivity is unlikely significantly different, it is the LNA amplifier anyway at the antenna that mostly defines the total RF sensitivity.
Considering how well an F9P rover works from an F9P base, I'd say the reference oscillator or even the antenna itself would make a significant difference for agriculture work (working at sub-inch accuracy).
The big names are not going to explain what is so much better on their products but I would have expected more detailed comparison from u-blox or those companies who build their products using u-blox F9P or similar receivers.
I believe one significant difference is the actual antenna. On the expensive receivers the antenna is some mechanical artwork. Needs to receive all frequencies at all angles at accurate phase difference etc.
The u-blox F9P performance is pretty close to that of the expensive receivers. Dual frequency support, multiple constellation support. Not so old commercial receivers were still limited to GPS + Glonass while F9P handles Galileo and Beidou too (like the expensive receivers do today).
There are some missing pieces with F9P that are difficult to understand for most of us farmers. One example is the GPS L2 signal support. F9P only supports the modernised GPS signal while the expensive ones make use of the older format too. Don't know the exact number of GPS birds that have not been upgraded but someone recently mentioned and order of 30%. Someone at this forum talked about another "missing code" issue but I could not find that discussion just now. That one was even more difficult to understand because RTK correction signal should be about the carrier phase between different birds and for different frequencies and I don't understand why any difference if the base receiver measures this from one code or another (assuming similar time resolution for both).
Obviously the accuracy of the local clock makes a difference and the more expensive (less integrated) products may have a significantly lower noise reference clock. The receiver sensitivity is unlikely significantly different, it is the LNA amplifier anyway at the antenna that mostly defines the total RF sensitivity.
Considering how well an F9P rover works from an F9P base, I'd say the reference oscillator or even the antenna itself would make a significant difference for agriculture work (working at sub-inch accuracy).
ERH Services LTD are the UK dealers of the FJDynamics autosteering kit. These are about half the price of those you mentioned and have the same RTK capabilities. Worth a look
Northern farmer to answer your question.........................................
It's not only the message types that are the problem, it's the carrier phase signal types.
L2C the newer civilian code isn't directly compatible with the older and widely used L2Y, L2W, L2P etc and will show an error of +-250mm. the quarter cycle of the phase has to be adjusted to align the phases.
Trimble reference stations push out L2C but corrects the quarter cycle to align it with the L2Y etc carrier pahses.
To the original poster
I can offer RTK corrections on an annual basis at a fraction of the cost of setting it up yourself
It's not only the message types that are the problem, it's the carrier phase signal types.
L2C the newer civilian code isn't directly compatible with the older and widely used L2Y, L2W, L2P etc and will show an error of +-250mm. the quarter cycle of the phase has to be adjusted to align the phases.
Trimble reference stations push out L2C but corrects the quarter cycle to align it with the L2Y etc carrier pahses.
To the original poster
I can offer RTK corrections on an annual basis at a fraction of the cost of setting it up yourself
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