Merge branch 'master' of github.com:peterantypas/maiana

README.md

@@ -3,11 +3,11 @@
 I started this project around 2015 with the intention of experimenting and eventually building something for my own boat.
 I was not impressed with commercial AIS class B transponders. They seemed bloated, expensive and some of them were particularly power-hungry. Also, my boat is rather small and I have very little room for "nav" instruments, so I didn't want a huge enclosure inside plus two external RF cables, one for VHF and one for GPS. So I set out to create my own "lean and mean" design and I sailed with it for 2 years.
 
-Fast forward to 2021, and several other sailors who are looking for the same features in an AIS unit asked me to build it for them. Here are some examples:
+Fast forward to 2023, and it has taken a life of its own:
 
-<img src="images/InstallOnSolarPanels.jpg" height="320"/><img src="images/InstallOnRadarDome.jpg" height="320"/><img src="images/InstallOnSternRail.jpg" height="320"/>
+<img src="images/InstallOnSolarPanels.jpg" height="320"/><img src="images/InstallOnRadarDome.jpg" height="320"/><img src="images/InstallOnSternRail.jpg" height="320"/><img src="images/swedish_oceanic.jpg" height="320"/>
 
-The main difference between MAIANA&trade; and every commercial transponder is that it's a self-contained unit, and thus its performance is 100% repeatable. The entire transponder circuit, the GNSS and all antennas are in the same housing. The design has been validated by fabricating _over 200 units_ now (May 2023).
+The main difference between MAIANA&trade; and every commercial transponder is that it's a self-contained unit, and thus its performance is 100% repeatable. The entire transponder circuit, the GNSS and all antennas are in the same housing. The design has been validated by fabricating _over 300 units_ now (July 2023).
 
 So with all the core functionality kept outside and under tight control, the only other thing we need is power and data connections. Now, what's the most common cable that can carry a few signals 50 feet away? If you guessed "Ethernet", you guessed right. Commonplace Cat5 cable can deliver power plus serial data signals anywhere on an average sized pleasure boat. So that's how the exterior unit connects to the cabin, where one of these breakouts offers USB, NMEA0183 or NMEA2000 adapters to connect to the rest of the boat's systems. 
 
@@ -31,11 +31,11 @@ As I mentioned already, the transponder circuit is inside the antenna case. It's
 
 ![Image](images/board-11.5.jpg?raw=True)
 
-The core design is based on two Silicon Labs "EZRadio Pro" series ICs. All kits shipping today are based on the Si4467 as this is the only part I have been able to source from spot markets in China.
+The core design is based on two Silicon Labs "EZRadio Pro" series ICs. All kits shipping today are based on the Si4460.
 
-The microcontroller on this board is a STM32L4 series (422, 431 and 432 supported). I chose these because the 80MHz clock allows the SPI bus to operate at exactly 10MHz which is the maximum supported by the Silabs RF ICs. This is important, as a transponder is a *hard real time* application so SPI latency must be minimized. All kits today are based on the STM32L432KBU6 as (again) it's the only part that I have been able to source from China.
+The microcontroller on this board is a STM32L4 series (422, 431 and 432 supported). I chose these because the 80MHz clock allows the SPI bus to operate at exactly 10MHz which is the maximum supported by the Si446x ICs. This is important, as a transponder is a *hard real time* application, so SPI latency must be minimized. All kits today are based on the STM32L432KBU6.
 
-The GNSS is now a Quectel L76L-M33 and relies on a Johansson ceramic chip antenna. It usually takes a minute to acquire a fix outdoors from a cold start. With the latest antenna tuning, it offers near-navigation grade accuracy (typical HDOP at sea < 1 meter).
+The GNSS is now a Quectel L76L-M33 and relies on a Johansson ceramic chip antenna. It usually takes a minute to acquire a fix outdoors from a cold start. With the latest antenna tuning, it offers near-navigation grade accuracy (typical HDOP at sea is less than 2 meters).
 
 The transmitter front end is based on a power MOSFET typically found in handheld VHF radios and outputs just over 2 Watts (+33dBm). It has a verified range of over 20 nautical miles on a masthead and 10+ miles on a pushpit.
 
@@ -53,7 +53,7 @@ SOTDMA synchronization is based on the very acurate 1 PPS signal from the GNSS a
 
 All adapters (except the "bare bones" one) feature a *silent mode* switch to explicitly disable transmission. If you need this for the UART adapter, you can wire one yourself.
 
-In terms of power consumption, the main board draws about 35mA from 12V in receive mode, and spikes up to 650mA during transmission (for only 27 milliseconds). The adapters add an extra 0.5mA - 25mA depending on choice. So MAIANA&trade;'s most power hungry configuration needs about 0.8 Watts, which is a lot less than a typical LED-based cabin light.
+In terms of power consumption, the main board draws about 45mA from 12V in receive mode, and spikes up to 700mA during transmission (for only 27 milliseconds). The adapters add an extra 0.5mA - 25mA depending on choice. So MAIANA&trade;'s most power hungry configuration needs about 0.6 Watts, which is a lot less than a typical LED-based cabin light.
 
 
 ### Software