Your download link is at the very bottom of the page... always.

Processed through Paypal
No account required.

Donate Bitcoin to this wallet:
Donate Ethereum to this wallet:
Donate Litecoin to this wallet:

Buy our over-priced crap to help keep things running.

Join our Facebook groupFollow us on TwitterFollow us on InstagramOur RSS FeedJoin us on TikTokJoin us on LinkedIn

 Home » Freeware Downloads » Toys, Fun Geek Stuff and Other Software » fldigi v4.1.20   
File - Download fldigi v4.1.20

Always scroll to the bottom of the page for the main download link.
We don't believe in fake/misleading download buttons and tricks. The link is always in the same place.

fldigi v4.1.20

Ham Radio Digital Modem Application

Fldigi is a modem program for most of the digital modes used by radio amateurs today: CW, PSK, MFSK, RTTY, Hell, DominoEX, Olivia, and Throb are all supported. It can help calibrate a sound card to a time signal and do frequency measurement tests.

Version 4.1.20
* Update release to both fldigi and flarq

Cosmetic changes
* Fix cosmetic issues reported by Bob, VK2YQA
* Fix parse of macro <PUSH>

Gleam scheme
* add fltk 'gleam' UI scheme

xmlrpc id
* add client ID to client requests
* add client ID to server parsing

cw tracking
* adjust tracking filter constants to improve power detection

Navtex modem
* make single bit flip correction guess a little smarter
The flip_smallest_bit code was written with the assumption that the
discriminator has equal weights for mark and space, that we are equally
likely to get things wrong in each direction, and that flipping the bit
with the smallest absolute value is likely to get us what might have been

However, in the face of selective fading and QRM, the assumption of
symmetry proved to be wrong. This is "helped" by the 3/4 framing of
SITOR-B, where every character has 3 marks and 4 spaces, resulting in
the mark value consistently getting a lower envelope estimation than
the space value, even when both are the exact same signal level!

Make the bit flip guessing a little smarter by correcting towards the
3/4 framing, but only if this character is only one off from a valid

This seems to result in slightly better message decoding in marginal

Smeter Pwr_meter
* correction to xmlrpc procedure to get smeter and power out meter from flrig

My Callsign
* modify edit code to maintain cursor position

Contest fields
* Change to Rx text field parsing
* Change to cut number parsing

gpio ptt
* fix for pi3/4 gpio h/w UDRC-II operation

Add OFDM modes for NBEMS
* OFDM-500F for HF SSB
- survives HF NVIS/long path
- 4-carriers of 62.5-baud 4PSK = 250 bps
- 1/2 rate K=15 FEC with 4sec interleaver
* OFDM-750F for HF SSB
- survives HF NVIS/long path
- 3-carriers of 125-baud 8PSK = 562 bps
- 1/2 rate K=13 FEC with 3.2sec interleaver
* OFDM-2000F for HF-SSB/FM
- 8 carriers of 125-baud 8PSK = 2000bps
- 2/3 rate K=13 FEC with 3.2sec interleaver
* OFDM-2000 for HF-SSB/FM
- 4 carriers of 250-baud 8PSK = 3000bps
- NO FEC, meant for line-of-sight
* OFDM-3500 for FM 9600-port
- 7 carriers of 250-baud 8PSK = 5250bps
- NO FEC, meant for line-of-sight
- Requires Signalink made-after 2018 connected to the 9600-jack
* OFDM-2000F CPU-load fix
- FEC of previous mode too heavy for some CPUs
. Reduced to: K=11 FEC with 1600msec interleaver
. Other mode parameters unchanged
* Added Vestigial-carrier based AFC to OFDM modes
- Increases robustness and tolerance to drift
* OFDM 2000F hold
- commented out OFDM 2000 and 2000F modes for bugfixes
- OFDM 500F, 750F, and 3500 are complete

This download is for the Windows version. All other download assets are below:




Click here to visit the author's website.
Continue below for the main download link.

Downloads Views Developer Last Update Version Size Type Rank
5,488 14,228 W1HKJ & Associates <img src=""border="0"> Apr 25, 2022 - 12:03 4.1.20 6.29MB EXE 5/5, out of 49 Votes.
File Tags
fldigi  v4.1.20  
Whoa! Slow down there, Speedy.
Read this and then continue to download below.

Like seeing no ads? No misleading/fake download buttons?
We like it too! This site has been kept alive for 15 years
because of people just like you who download and donate.
No one is stopping you from downloading without donating
but the site runs on the "Honor System". If your momma
raised you to be honorable, make a donation and download
'til ya turn blue. Make your momma proud!

Thank you ! -Randy & Deanna (The Older Geeks)

Monthly operating costs = $750
Donations cover operating costs first
then are set aside for future upgrades and/or
handed-over to Deanna for new shoes.


Send a check payable to Home Computer Repair LLC, 208 E. Water St. Mount Vernon, MO 65712

Recent Super Donors ($50+)
Thanks, Brian
Thanks, Donald
Thanks, Daniel
Thanks, Will

Recent Donors
Thanks, Grant
Thanks, Ronald
Thanks, Bruce
Thanks, Alan
Thanks, Ricky
Thanks, Michael
Thanks, Thomas
Thanks, Keith
Thanks, Ronald
Thanks, Everald

→ Download Your File ←

Click to Rate File     Share it on Twitter → Copyright (c) 2024