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Author Topic: Sending A Spreadsheet Via HF Digital Modes  (Read 5393 times)
KE5HJO
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Posts: 207




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« on: July 28, 2009, 11:37:14 AM »

Is it possible to send an Excel spreadsheet to someone using digital modes on HF?  If so, how?  What mode is best?  How do I select the file for sending?

I'm using fldigi http://www.w1hkj.com/Fldigi.html and an FT-897D rig.

Thanks!

Mike
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N3OX
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« Reply #1 on: July 28, 2009, 11:50:13 AM »

I think you wanna use flarq:

http://www.w1hkj.com/FlarqHelpFiles/flarq.html

For big binary files, it's pretty critical to use "automated repeat request" or ARQ to make sure the whole thing gets through efficiently.

MT63 is the mode specifically mentioned in the ARQ documentation...

http://www.w1hkj.com/FlarqHelpFiles/ARQ2.pdf

73
Dan
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73,
Dan
http://www.n3ox.net

Monkey/silicon cyborg, beeping at rocks since 1995.
KE5HJO
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Posts: 207




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« Reply #2 on: July 28, 2009, 12:21:01 PM »

That was easy.  Thanks!

Now, is there a common frequency where folks sending and receiving files can be found?
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W3YJ
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« Reply #3 on: July 29, 2009, 07:52:59 AM »

You can also use Wrap:
http://www.w1hkj.com/Wrap/index.html  and
http://www.utipu.com/app/tip/id/10396/
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W3YJ
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« Reply #4 on: July 29, 2009, 08:01:42 AM »

Also, I would suggest you join the NBEMSham group...this is where you'll be able to get excellent advice from the NBEMS developers and users.

http://groups.yahoo.com/group/NBEMSham/
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N3OX
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« Reply #5 on: July 30, 2009, 08:34:56 PM »

You may also also want to read about file sizes on the page about wrap !

Excel might not be the best choice :-)
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73,
Dan
http://www.n3ox.net

Monkey/silicon cyborg, beeping at rocks since 1995.
W3YJ
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Posts: 3




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« Reply #6 on: July 31, 2009, 05:33:32 AM »

Yes!  In general, we do not have sufficient bandwidth to send binary files in a timely fashion.  Export the spreadsheet first as a CSV file and then send it.
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WB2YZX
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Posts: 16




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« Reply #7 on: August 01, 2009, 12:15:15 PM »

If you are going to do this on a regular basis I suggest the Pactor modes. This of course requires a TNC which can incur considerable expense.
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AA4PB
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« Reply #8 on: August 01, 2009, 03:56:25 PM »

You'll loose a lot of information when you export the spread sheet as a csv file. It all depends on what's in the spread sheet and what you wan't to do with it on the other end. Exporting to csv reduces the file size but it is not a "universal" answer. Compressing the spread sheet into a zip file will reduce the size for transmission without loosing any information.
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K6DPY
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« Reply #9 on: November 28, 2012, 11:17:56 AM »

What are the excel (and jpeg) file-size limitations for these transfers on VHF/UHF bands?  I assume HF bands have lower limitations.

Thanks.
Dan
K6DPY 
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KG4RUL
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« Reply #10 on: November 28, 2012, 05:55:48 PM »

What is lacking here is detail.  How big of a file are you actually wanting to transfer?  The time required to transfer some large spreadsheet files may make this a non-starter.
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KC9SGV
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Posts: 31




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« Reply #11 on: December 07, 2012, 10:44:20 AM »

Hi,

Check out Winmor for spreadsheets, pictures, maps, large text files, GRIB files, weather sat. pictures, etc.

Fast, efficient. Do not re-invent the wheel.
And you can do this with free software (unless you want to donate to the developers.)
You do NOT need an expensive TNC.

KC9SGV
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AA4HA
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Posts: 1482




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« Reply #12 on: December 08, 2012, 04:24:12 AM »

You'll loose a lot of information when you export the spread sheet as a csv file. It all depends on what's in the spread sheet and what you wan't to do with it on the other end. Exporting to csv reduces the file size but it is not a "universal" answer. Compressing the spread sheet into a zip file will reduce the size for transmission without loosing any information.

WOW, this old thread received a big bump. There are some good things to bring out;

File compression is a great point. I would do both, use a CSV (comma seperated variable) file format and some ZIP-type or on the fly compression system.

One time I had to write an EDI (electronic data interchange) application to move spreadsheet type data from a Windows application into an IBM mainframe. CSV was the format I used as it did not have any of the formatting that is embedded in an Excel-type application (fonts, spacing, field types, etc...). All I cared about was the data. I was able to move a significant amount of information across a 300 baud type telephone modem (the same baud rate we can use on HF).

Radio, and particularly HF radio is subject to all sorts of effects like fading and impulse noise that will cause data drop-outs. You want to move your data in as small of packet sizes as you can so your total errors are lower (the error rate will be the same but because it may only be 10-20% of the larger data transaction size your errors will go down significantly).

CSV's are very easy to understand. It is just blocks of data, separated with commas. It would look similar to this;  1,1542,65,Y,N,3,54...  Your application knows to put the first value in the first cell, look for the comma and put the next value in the next cell, and so on.

Using an application like ZIP will give you compression but also features like CRC (cyclic redundancy check) error detection so you will know about single bit errors and toss out a corrupted packet as invalid. If you were using something like FEC (forward error correction) that validates each packet by two way communications across the radio link you can also improve reliability.

Remember that we cannot encrypt data but I think that since ZIP is a mostly open standard that anyone can use it might be acceptable to use that (ask the legal eagles on here that question).

---------------------
I ran a test, I took one of my Excel spreadsheets from work that has 437 cells (23 rows, 17 columns, some cells up to 13 characters in length, mixture of numbers and text). Here is what it looked like;

Excel format      16,384 bytes       131,072 bits      300 baud      436 seconds to send
CSV format         4,765 bytes         38,120 bits      300 baud      127 seconds to send
PDF format       114,688 bytes      917,504 bits      300 baud     3058 seconds to send
CSV and zip         1,468 bytes       11,744 bits       300 baud        39 seconds to send

I used the free program, 7-Zip and used the maximum compression (no encryption).

This does not include any sort of packetization (breaking those big transmissions into chunks) or any sort of FEC.
« Last Edit: December 08, 2012, 05:05:43 AM by AA4HA » Logged

Ms. Tisha Hayes, AA4HA
Lookout Mountain, Alabama
N1ZZZ
Member

Posts: 161




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« Reply #13 on: December 16, 2012, 02:39:18 AM »

To answer Dan's question about size on VHF/UHF, the old saying "size doesn't matter" works.

On VHF, and better yet UHF and SHF, you have a lot more bandwidth than HF.  On a HSMM or D-star DD link, an excel file of moderate size would take a few seconds.  If you are playing with 1200 baud packet, it's going to take awhile.  If you have a 9600 baud packet, a few minutes if the link is good. 

On the 500 Hz wide Pactor II/Clover/Winmoor, 35-50 KB of binary file is about as big as I'd go for.  Anything larger and you will have quite a long link.  Under good conditions that will still take you about 10 minutes to transfer.

If you had Pactor III or Clover 2000/2500 you can cut that to about 5 minutes, but you are now in 2.4 KHZ bandwidth range and paying quite a bit for a modem to operate it.

My contacts in Europe using Pactor IV say that under moderate to good conditions, 50 KB is no problem at all, but unfortunately we can't use that mode, and it costs quite a bit.

My suggestion is that if you need to move files as complicated as Excel or jpgs, you should look to short range UHF links with high speed modes.  HF digital modes work best with text which can be easily compressed (50% is not unusual). If you need to move a photo, use SSTV.

73
Jeremy N1ZZZ
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