Art
- 19th May 2015, 17:46
Hi Guys :)
I wanted to show a new project which is an add on for an older project.
And an idea why timing math problem might make a headache ;)
and to show off.
It’s a GPS made back in the 1920’s when GPS first arrived on the scene.
It’s a Ublox LEA-5T timing module, I think now a generation behind the current one.
15ns timing error when in timing mode and kept stationery after an auto position survey.
I’m using positioning mode which is 30ns timing error.
There is a copper plane under the module insulated with a thin dielectric.
The antenna is QFH (Quadrifillar Helecoidial) backfire antenna for L2 (1.575 GHz),
and is made with copper elements, brass tube stem (as they did back in that age),
and rigid coax fed through to the tip of the antenna. It’s a backfire antenna,
because if it was a transmitter, it would radiate toward the feed point at the tip of the antenna.
The SPI EEPROM is for faster startup time by storing almanac information,
but I did not use it in the end, I gathered it just start fresh each power cycle.
The Ublox timing module was salvaged form an existing product board that was rejected by
the manufacturer, and I had to remove it. Out of six modules, this was the only one successful
where I didn’t lose some pads off the module. It later got a frequency output SMA connector
underneath which isn’t present in the photos. Hope you like it :)
I wanted to show a new project which is an add on for an older project.
And an idea why timing math problem might make a headache ;)
and to show off.
It’s a GPS made back in the 1920’s when GPS first arrived on the scene.
It’s a Ublox LEA-5T timing module, I think now a generation behind the current one.
15ns timing error when in timing mode and kept stationery after an auto position survey.
I’m using positioning mode which is 30ns timing error.
There is a copper plane under the module insulated with a thin dielectric.
The antenna is QFH (Quadrifillar Helecoidial) backfire antenna for L2 (1.575 GHz),
and is made with copper elements, brass tube stem (as they did back in that age),
and rigid coax fed through to the tip of the antenna. It’s a backfire antenna,
because if it was a transmitter, it would radiate toward the feed point at the tip of the antenna.
The SPI EEPROM is for faster startup time by storing almanac information,
but I did not use it in the end, I gathered it just start fresh each power cycle.
The Ublox timing module was salvaged form an existing product board that was rejected by
the manufacturer, and I had to remove it. Out of six modules, this was the only one successful
where I didn’t lose some pads off the module. It later got a frequency output SMA connector
underneath which isn’t present in the photos. Hope you like it :)