Anthony Wooldridge
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Anthony Wooldridge's Page

Profile Information

About Me:
electronics enthusiast
Please tell us a bit about your UAV interest
interested in gps and 6 axis gyro/ imu kalman filtering

Comment Wall (5 comments)

At 2:30pm on April 21, 2011, Ita G said…

Thank you for your reply.

I won't be needing the USB modification. The USART port should be enough for what I want to do (RTK using RTKLIB).
I believe I'd like to purchase two (2) units at this time, and perhaps get a few more in a few months. How many do you have in stock?

I do have a couple of question and requests before we proceed (please feel free to take the time to get back to me) - 
1. What is the condition of the boards you'd like to sell? Have they been used? Have they been tested for performance in any way?
2.  Can you supply a schematic for the boards? (or, at the very least - pinout information) 

3. Could you send me some pictures of the boards? (this is really a "nice-to-have" more than a requirement).

4. You mentioned in one of your posts that you could offer some help with DIY antenna design that is suitable for RTK.
I'm quite interested in any advice for an good (yet cheap) antenna solution... Are you willing to share your advice and/or sell any of your antenna assemblies?
5. Could you provide estimated shipping costs to Israel? (for two boards)

6. How would you like to do the money transfer? Is PayPal good for you?

Kind regards,

At 6:57am on April 22, 2011, Anthony Wooldridge said…


The units are used but in good working order and as new condition. I have tested many and they all work well on RTKlib.

If you give me your email address I can send a photo, with reverse engineered circuit diagram.

There is a pin header 8 pin (2 rows of four on 2mm pitch) with timer output(out plus 0v return), serial in/out, Antenna power in, 0v and +5volt power in. (three volt regulator on board for lea4T ) There is a spare pin that looks like it was for a reset input but the components for that need soldering in if you need it.

It has an smb antenna plug (male center pin) and all antenna short circuit supervisory circuitry in built on board.

It is a professional multilayer circuit board 32mm x 66mm

It has a capacitor as battery backup, but if you need more than that you will need to add say a supercapacitor or

rechargeable backup battery.

Postage and packing airmail to Israel will be £7 GBP.

I have a reasonable quantity  >>10 , but I will need quite a few for my own purposes. however I can release a few for non profit use.

What is your application?

I am developing an RTK GPS system for Agriculture. Provided you do not disclose my antenna solution, I can share it, but not for commercial use without my permission.

I use antenna available on the surplus market at around $30 each with a purpose built choke ring of my own design.

Unfortunately they are quite heavy and postage would be very high.

We manufacture the choke rings in the UK and would sell them at £72 each plus postage.

Postage would be around £60 GBP unfortunately.

Import duty may also be applicable at your end.

But you could use practically any survey grade antenna provided its amplifier power supply is compatible.





At 9:49am on July 23, 2011, dyke said…

Ok, thanks for your answer.


I´m interesting to buy one of the LEA-4T modified, but, Could you send me some photos? My e-mail is:

I´m from Spain, The price is £75, Is the same price with the shipping cost to Spain?

Also I want to ask you about the precision that I colud get with this rtk low cost system.

The use is for agriculture applications.

I think it is depends on the antenna. Could you recomend me some antennas?

I was thinking to buy the ublox ann-ms antenna.

Do you know Where I could buy this antenna? For buy the 4t and antenna together.


At 4:44pm on September 11, 2011, Lawrence E. Stoskopf said…

Just starting to look at RTK guidance for very small agriculture use.  Just retired anesthesiologist with 60 years of ham radio experience looking for a project!  Could use a couple of your LEA-4T modules and any pointers  you might have in using RTKLib before I jump in.  Thanks,  N0UU

At 2:41am on May 26, 2012, Daniel Berglund said…

HI Anthony

I am also interested in buying some Lea-4T:s. I read some of your posts and I saw you referred to development boards and Lea-4T. Are the development boards something you have designed or are they some standard u-blox boards?

Please can you send med some information about the development boards. Do you have standalone Lea-4T modules also?


Best Regards



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