AshGPS: Firmware, Software Update Notification
for Ashtech, Magellan Professional, Thales Navigation
Friday 17 May 2012
Narrow Banding RTK Base Radios, CHAPTER 2...
IMPORTANT: MicroSD Cards for MobileMapper 10
Narrow Banding RTK Base Radios: Chapter 2
In February I sent some information regarding FCC required narrow-banding information. (You can read my original note here).
Last week I received some important additional 'Official' information from Pacific Crest which I would like to share with you (the links below are all PDF documents):
Pacific Crest Product Bulletin - Narrowbanding Update
FCC Narrowband FAQs
Configuring radios for narrowbanding
Applying for a 25 kHz FCC license

Based upon this new information, I believe that I made three 
incorrect claims (at least I am admitting to three):
1. Your existing 25 KHz FCC license (for baud rates less than 19,200) will terminate January 1 2013 (the end of this year.)

1. If you do nothing, your old license may automatically cover you for 12.5KHz operation until it expires. See " Applying for a 25-KHz License" (link above):   'You will not need to contact the FCC regarding existing licenses as long as you have a valid license and operate within the narrowbanding strictures.'
I recomended that you use a licensing service to narrowband your existing license.
The document "Applying for a 25-KHz License" (above) shows how to modify or apply for a new license using the FCC website.


I now believe that there is one legal way after Jan 1 2012 to use an existing 25KHz PDL base to broadcast 19,200 baud at 25KHz using an existing 25 KHz license:

19,200 bps with Transparent EOT/EOC, Packet Switched or Fast Async protocols and with 4FSK modulation.

However, this mode (19,200, EOT, 4FSK) will have limited range. See 'FCC Narrowband FAQ's': "Q: Will the FCC’s Narrowbanding requirements decrease the range of 25 kHz PDL radios?" In addition, radios from other manufacturers may not be compatible.
To summarize,
1. I still think it is worth narrowbanding your existing license. You may be able to do this yourself, but even with the step-by-step instructions it probably makes sense to pay a licensing service to take care of it for you.
2. You really do need to upgrade to a 12.5 KHz base radio. Consider doing it soon.
3. I still believe that 4800 bps operation with existing rover radios is the best protocol if you have older equipment.
Micro SD Cards for the MobileMapper 10
The 'User's Manual' for the MobileMapper 10 recomends that you use SANDISK Micro SD cards.
After some user complaints, last week I purchased a few (nearly 75) cards:
and it is my personal opinion that the 'Transcend' brand is a MUCH BETTER CHOICE. Here are the SD Card Facts as I know them:
  Most 2-GB SanDisk cards work
  Some 4-GB SanDisk  cards work, some don't. I can't visually tell the differnce.
  No (none) 8-GB SanDisk cards work
  EVERY SINGLE Transcend 4 GB and 8 GB card that I tested worked with no issues
For background, there is a little 'C' on the cards:
Inside the 'C' is a number: 2, 4, 6 or 10. (In the image above, there is a 6). The number is the 'Class' and higher is faster. '6' indicates that the card will write 6 million bytes per second to a card in a fragmented state.
The HC stands for 'High Capacity'. The original cards were 'Standard Capacity' (SC). There are also SDXC (eXtended Capacity).
There are reportedly over 400 brands of SD Cards and over 8,000 card models. I only tested SanDisk and Transcend.
This AshGPS Mail List
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Good survey and mapping to you all! 
Mark Silver,
Igage Mapping Corporation,, +1 801-412-0011 x16
iGage Mapping Corporation, 1545 S 1100 E, Salt Lake City UTAH USA