Docs v30 update

Author: nseidle

docs/gis_software.md

@@ -40,19 +40,8 @@ We need to send RTCM correction data from the phone back to the RTK device so th
 
 Enter your NTRIP Caster credentials and click connect. You will see bytes begin to transfer from your phone to the RTK Express. Within a few seconds, the RTK Express will go from ~300mm accuracy to 14mm. Pretty nifty, no?
 
-### What's an NTRIP Caster? 
-
-In a nutshell, it's a server that is sending out correction data every second. There are thousands of sites around the globe that calculate the perturbations in the ionosphere and troposphere that decrease the accuracy of GNSS accuracy. Once the inaccuracies are known, correction values are encoded into data packets in the RTCM format. You, the user, don't need to know how to decode or deal with RTCM, you simply need to get RTCM from a source within 10km of your location into the RTK Express. The NTRIP client logs into the server (also known as the NTRIP caster) and grabs that data, every second, and sends it over Bluetooth to the RTK Express.
-
-Don't have access to an NTRIP Caster? You can use a 2nd RTK product operating in Base mode to provide the correction data. Checkout [Creating a Permanent Base](https://sparkfun.github.io/SparkFun_RTK_Firmware/permanent_base/). If you're the DIY sort, you can create your own low-cost base station using an ESP32 and a ZED-F9P breakout board. Check out [How to](https://learn.sparkfun.com/tutorials/how-to-build-a-diy-gnss-reference-station) Build a DIY GNSS Reference Station](https://learn.sparkfun.com/tutorials/how-to-build-a-diy-gnss-reference-station). If you'd just like a service, [Syklark](https://www.swiftnav.com/skylark) provides RTCM coverage for $49 a month (as of writing) and is extremely easy to set up and use. Remember, you can always use a 2nd RTK device in *Base* mode to provide RTCM correction data but it will be less accurate than a fixed position caster.
-
 Once you have a full RTK fix you'll notice the location bubble in SW Maps turns green. Just for fun, rock your rover monopole back and forth on a fixed point. You'll see your location accurately reflected in SW Maps. Millimeter location precision is a truly staggering thing.
 
-### SWMaps and iOS
-
-SWMaps is available for iOS [here](https://apps.apple.com/us/app/sw-maps/id6444248083). Please note that Apple products do not support Bluetooth SPP so the Bluetooth protocol on the RTK device needs to be switched from SPP to BLE. More information is available on the [System Menu](https://docs.sparkfun.com/SparkFun_RTK_Firmware/menu_system_status/).
-
-
 ## Field Genius
 
 [Field Genius for Android](https://www.microsurvey.com/products/fieldgenius-for-android/) is another good solution, albeit a lot more expensive than free. 
@@ -415,5 +404,30 @@ Select the Positioning Menu. Then, with your RTK device on and in normal mode (n
 
 Once connected exit out of the menus and see position information within your project.
 
-## Other
+## Other GIS Packages
+
 Hopefully, these examples give you an idea of how to connect the RTK product line to most any GIS software. If there is other GIS software that you'd like to see configuration information about, please open an issue on the [RTK Firmware repo](https://github.com/sparkfun/SparkFun_RTK_Firmware/issues) and we'll add it.
+
+## What's an NTRIP Caster? 
+
+In a nutshell, it's a server that is sending out correction data every second. There are thousands of sites around the globe that calculate the perturbations in the ionosphere and troposphere that decrease the accuracy of GNSS accuracy. Once the inaccuracies are known, correction values are encoded into data packets in the RTCM format. You, the user, don't need to know how to decode or deal with RTCM, you simply need to get RTCM from a source within 10km of your location into the RTK Express. The NTRIP client logs into the server (also known as the NTRIP caster) and grabs that data, every second, and sends it over Bluetooth to the RTK Express.
+
+## Where do I get RTK Corrections?
+
+Don't have access to an NTRIP Caster or other RTCM correction source? There are a few options.
+
+The [SparkFun RTK Facet L-Band](https://www.sparkfun.com/products/20000) gets corrections via an encrypted signal from geosynchronous satellites. This device gets RTK Fix without the need for a WiFi or cellular connection.
+
+Also, you can use a 2nd RTK product operating in Base mode to provide the correction data. Check out [Creating a Permanent Base](https://sparkfun.github.io/SparkFun_RTK_Firmware/permanent_base/). 
+
+If you're the DIY sort, you can create your own low-cost base station using an ESP32 and a ZED-F9P breakout board. Check out [How to Build a DIY GNSS Reference Station](https://learn.sparkfun.com/tutorials/how-to-build-a-diy-gnss-reference-station). 
+
+There are services available as well. [Syklark](https://www.swiftnav.com/skylark) provides RTCM coverage for $49 a month (as of writing) and is extremely easy to set up and use.
+
+## Apple iOS
+
+The software options for Apple iOS are much more limited because Apple products do not support Bluetooth SPP. That's ok! The SparkFun RTK devices support Bluetooth Low Energy (BLE) which *does* work with iOS.
+
+We recommend SWMaps for iOS. SWMaps is available for iOS [here](https://apps.apple.com/us/app/sw-maps/id6444248083).  
+
+More information is available on the [System Menu](https://docs.sparkfun.com/SparkFun_RTK_Firmware/menu_system_status/) for switching between Bluetooth SPP and BLE.