SparkFun Forums

[haimira]

Hello everybody !!
I wish to use the Lassen iQ Evaluation Board - RS232 for connecting and communicate the Thales AC12 OEM Board, the AC12 board have 8-pin power/input/output connections:
vcc
v_ant
v_back
gnd
rtcm
rxd
txd
1 pps
The AC12 board utilizes CMOS signal levels and also compatible with external TTL level signals.

I will appreciate your help - is it possible ?? will it work??

Best,

[coyotebush]

One way to interface with the AC12 is to use a usb-serialTTL converter. It provides provides power, data signals, and usb-serial conversion. Spark has several, and the FTDI TTL-232-R cable is particularly easy to use.

If you order the connector which comes with the AC12, you *can* force the 2mm pins into a .1" prototype board.

[coyotebush]

I forgot to add ... Most GPS survey antennas run on 5V, so you probably want to run everything on 5V to keep it simple.

[haimira]

Dear coyotebush,
Thank for your help,
Do you have any experiment with this AC12 board?
Best

[coyotebush]

I have a picture at http://www.precision-gps.org/ThalesAC12.htm. The site also has source code for talking to the AC12, although the double differencing software is only marginally working.

[coyotebush]

Oops. Drop that final "." from the URL.
http://www.precision-gps.org/ThalesAC12.htm

[haimira]

Very impressive, Is it your work?

[coyotebush]

Yeah, I'm the guilty party. The kinematic double differencing problem is "hairier" than I realized. The biggest problem is detecting cycle slips - if you get bad data then the results go all awry.

I've come to the conclusion, that to really detect slips, you need to resolve the integer ambiguities and monitor the equations very closely. You also need to have redundant satellites (5 to detect slips), although other techniques may work for static receivers. The commercial providers are starting to do RTK with single frequency receivers, so the problems are solvable.

I sure wish we had Galileo and/or Compass to augment GPS. The combined constellation would give plenty of redundancy and should make cheap RTK really practical.

[haimira]

Dear Coyotebush,
Yes,
The Magellan Promark3 series provide very nice RTK solution ( Up to 10 KM vector , I think..) using single frequency receiver.

You can consider combination of MEMS component that becam more and more cheap this days..

Maybe several calculation cicels will be useful.

What is your opinion regarding the new SF Eval board? -->
http://www.sparkfun.com/commerce/produc ... ts_id=8334
Do you think its will be appropriate to run the AC12?