Topic: Humminbird .SON File format question

[jgann]

Hello,

Is anyone able to answer these 3 questions about the Humminbird .SON file format?

1) Is there a bit field that indicates which channel is represented by a particular .SON record?  That is, how to tell the port sidescan from the starboard sidescan from the downlooker?  I've been trying to look at the values following type bytes 0x53, 0x56 and 0x57 but I haven't been able to work out a bit that is toggling in the order I expected.

2) How do you work out the range of the ping either in time or distance?  I know that the number of samples per record are provided by the 4 bytes following the "A0" byte.  If the A/D sampling frequency were known then one could determine the time and assuming a sound velocity compute a distance.

3) Are the echogram sample values 8 or 16 bit samples?  Are the sample values linear or in dB?

Thanks,

jgann

[RGecy]

jgann,

Welcome to the forum.  If I might ask, what are you working on?  I have more information available if you would like to PM or email me. 

1) Is there a bit field that indicates which channel is represented by a particular .SON record?  That is, how to tell the port sidescan from the starboard sidescan from the downlooker?  I've been trying to look at the values following type bytes 0x53, 0x56 and 0x57 but I haven't been able to work out a bit that is toggling in the order I expected.

Yes, its in the header of each ping at byte #35.  It will be either 00, 01, 02, or 03.  But you should know the channel by the SON file name also.  B000 is the 50/83khz, B001 is the 200khz, B002 is the Port SI, B003 is the Strbd SI.

2) How do you work out the range of the ping either in time or distance?  I know that the number of samples per record are pro
vided by the 4 bytes following the "A0" byte.  If the A/D sampling frequency were known then one could determine the time and assuming a sound velocity compute a distance.

Well, this one is a little more complicated.  Humminbird uses the Velocity of Sound in water as a constant versus computing based on temp, salinity, etc.  So basically, the unit sends out the ping, and based on the range set in the unit, it listens for a certain amount of time.  The number of bytes recorded will reflect what range was set.  Take a recording with a known range and divide the number of samples per ping by the range.  There are approx ~15.34 bytes per foot or ~33.52 per meter.

3) Are the echogram sample values 8 or 16 bit samples?  Are the sample values linear or in dB?

8 bits (1 byte).  Linear values, representative of the signal strength returned.

Hope this helps.  Please let me know if there is aything I can do for you.

Robert

[jgann]

Hi Robert,

Our company produces software for acquiring and post-processing sidescan and sub-bottom profiler data.  So, I have been working on adding support for the Humminbird data format to our SonarWiz product.

Thanks very much for the information, I bought a Humminbird unit for my personal use at the end of 2009 and I've been eager to get this working for my own selfish reasons. 

Best,

John

[Chiboo]

Hi, John.

Whether it is planned in SonarWiz to use the online data from HB Ehternet port?

[jgann]

I would love to add the real-time interface for the HB.  I didn't realize there was an Ethernet output.  Is that an optional item?  Do you know where I might find the technical specs on the Ethernet interface?

Thanks,

John

[Chiboo]

HB announced inclusion Ehthernet port in models 2011 and in current 700,900,1000 models in new firmware... It is necessary to wait a little....

[phb]

Hi,
i am trying to decode files from my DI device HB 788.
It seems that codes and logic for SON Files from DI device  look different  for SON files out of SI device.
I found some pieces of codes in C# for  and adapted it to DI.
I succeed now to read pings but I found what I thing is position but I am unable to  decode them. It looks like encoding is integer instead of double as for SI.
I am looking for dat file format too.

Can anyone help?

here are the different SI and DI headers I found:
/*
 * SI Header = 62 bytes
1-4 = Always the same
5 = Spacer
6-9 = Return Key, ties back to index file
10 = Spacer
11-14 = Time in milliseconds since recording started
15 = Spacer
16-19 = Long in Mercator Meters
20 = Spacer
21-24 = Lat in Mercator Meters
25 = Spacer
26-29 = GPS Dependent, not sure what it is yet
30 = Spacer
31-34 = GPS Dependent, not sure what it is yet
35 = ?
36 = Beam #
37-39 = ?
40-43 = Frequency
44-57 = ?
58-61 = Sentence Length
62 = Spacer, or something that’s always x21
*/

/*
 * DI Header = 68  bytes
1-4 = Always the same "c0 de ab 21" meaning?
5 = Spacer - 80 meaning?
6-9 = valeur pour "80"
10 = Spacer - 81 meaning?
11-14 = Time in milliseconds since recording started
15 = Spacer - 82
16-19 = Long in Mercator Meters ?
20 = Spacer - 83
21-24 = Lat in Mercator Meters ?
25 = Spacer - 84
26-29 = GPS Dependent, not sure what it is yet
30 = Spacer - 85
31-34 = GPS Dependent, not sure what it is yet
35 = Spacer - 87
36-39 = GPS Dependent, not sure what it is yet
  = 0 = B000 50/83KHZ
     1 =  B0001 200kHz
 *   2= B0002 Si droit
 *   3 = B0003 SI Gauche
40 =  Spacer - 50 Beam #
41 = ?
42 = Spacer - 51 Beam #
43 = ?
44 =  Spacer - 92 lat? #
45-52 = lat double mercator?
53 =  Spacer - 95 lon? #
54-61 = lon double mercator?
53 =  Spacer - A0
54-67 = nombre de pings
68 = Spacer, or something that’s always x21

 * * le fichier index .idx a la forme:
0 - 7 = temps en ms? de l'enregistrement courant
8 - 17 = index de l'enregistrement suivant
*/

[ruiner]

Does any one know that what is the unit of speed recorded?

I keep seeing values of 72-82 or so, but I have no idea of the unit (USA version, so could be anything). I am trying to do a custom SON file viewer, hence the question. I need to know the speed to correct aspect ratio of the image. I suppose I could use the lat and lon stamps as well, but it seems silly since there is speed provided...

[ckd022]

HB seems to use SI units, so as far as I can tell it is in "10ths of m/s".  I convert the two speed bytes into decimal and multiply by 0.223693629 to get to MPH.  At least when I do this my speed matches the one produced by Humviewer.

[ruiner]

Thanks!

Indeed it seems so

Timestamps seems to be in milliseconds, ping about every 795 millisecond or so...

[ckd022]

Agreed, timestamps are in ms and I had the GPS heading in bytes 28-29 of the 68 byte header in 10ths of a degree for what it is worth.

[ruiner]

Does anyone know if calculated depth information is recorded in the record files or the temperature? If they are, which fields they are exactly? Thanks

[ckd022]

I don't know if temp is recorded, I haven't looked for it.  But depth is recorded at 38-39 and is stored in 10ths of a meter.