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Re: [Paparazzi-devel] UBX vs NMEA Protocol Inquiry

From: Stephen Dwyer
Subject: Re: [Paparazzi-devel] UBX vs NMEA Protocol Inquiry
Date: Thu, 1 Mar 2012 13:25:49 -0700


Another nice thing about binary is you are guaranteed messages of a
specific length. With NMEA if all fields are 0 or something like that,
you might get a message of only 20 or 30 bytes in length, but with all
values populated to near maximums, you will get closer to the limit,
up to perhaps 70 or 80 bytes in length. This is much less predictable
than being able to specify the same number of bytes and the same value
in the same offset location in a binary message, and varies the
timing. This in addition to the fact it takes more effort to convert
numbers from text representation to binary representation, which takes
more time than either using the value raw or doing a simple operation
like scaling the value.

And NMEA sucks, as mentioned several times before. :)

-Stephen Dwyer

On Thu, Mar 1, 2012 at 12:48 PM, Roman Krashanitsa
<address@hidden> wrote:
> Chris, you still sort of have to match the binary frames to the message
> types but you dont have to convert textual representation of numbers into
> binary form. Some may argue, but I think this is not the main reason why
> NMEA is not good compared to proprietary ublox binary protocol. NMEA is just
> a poor standard, it is not robust and the minimum spanning set of commands
> is too small. I think wiki will do a better job than me explaining this.
> Roman
> 2012/3/1 Chris Wozny <address@hidden>
>> All,
>> I was wondering if someone had a technical explanation as to why the
>> UBX protocol is faster than NMEA parsing. I know in the past people
>> have said NMEA sucks and binary protocol's are faster, but I just want
>> to make sure I understand the technical reason. I know parsing ASCII
>> strings requires more CPU cycles, but don't you still have to parse
>> the UBX output as well?
>> Best,
>> Chris
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