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Let's be clear at the outset - there are many such signals that will '''never''' be decoded. Most are assumed to be military in nature. The challenge is to find signals that '''can''' be decoded, or at least identified.  
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Digital signals come in 2 basic flavors - those as used by the amateur radio community, and those used by organizations such as the military, aeronautical, maritime and several other users. While the modes used by amateur radio are, by both law and convention, never encrypted, there are several in the military and others that encrypt their signals so they can't be monitored by the casual listener. The challenge here is to find signals that are readable, or at least, where the user can be identified.
  
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Please see the following articles for more information:
  
If you decide to get into digital, you will need better equipment than a simple portable. While some portables will work with reasonably stronger signals, the more complex the signal (or conditions), the more a portable will fall short. Tuning accuracy, selectivity, stability and even mode selection play a significant role in being able to correctly tune a signal. <br>
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* [[HF Digital Amateur Radio]]
While the number of newer desktop receivers has plummeted, a sharp eyed listener can often find such receivers at hamfests. Do your homework - use the [[:Category:Receiver Reviews|Receiver Reviews]] article to begin your research. Even though most of the reviews do not specifically refer to digital capabilities, keep an eye on some of the characteristics mentioned earlier. Those folks with a modern ham transceiver have an advantage - they often have a general coverage receiver built in.
 
  
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* [[DXing Digital Utilities]]
  
With propagation as lousy as it's been lately, a good antenna is an absolute must. The better the antenna the better the results will be, whether it's tuning digital signals or something else. See our [[HF Antennas]] article for more on this topic.
 
  
 
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[[Category:HF Signal Analysis and Decoding]]
A critical part of any digital receiving station is a clean connection from the receiver to the PC. There are many ways to accomplish this without going through the expenditure of having a dedicated interface, although one is often used in the amateur service. Please see our [[Connecting Radios to Soundcards]] article for more information.
 
 
 
The RR forum for this article can be found [http://www.radioreference.com/forums/digital-signals-decoding/ here]
 
 
 
==Amateur Radio Digital==
 
By far the easiest place to start in this field is the amateur service. But don't be fooled - although, by regulation, no digital mode can be uncopyable, specialized software will be required to decode them. See the software section on this article for more on this.
 
 
 
* Here is a list of common [http://en.wikipedia.org/wiki/List_of_amateur_radio_operating_modes Amateur Radio Operating Modes]
 
* Digital amateur signals are restricted to certain portions of the bands. [http://www.arrl.org/FandES/field/regulations/allocate.html Here] is a general list of bands which shows the sections restricted to CW(Morse Code) and digital
 
* These links are courtesy of HFLink.org;
 
** [http://hflink.com/channels/  ALE Amateur]
 
** [http://hflink.com/jt65/  JT65]
 
** [http://hflink.com/olivia/  Olivia]
 
* [http://www.arrl.org/w1aw.html#w1awsked W1AW CW/Teleprinter schedules]
 
* [http://hfradio.org.uk/html/digital_modes.html G4UCJ website]
 
 
 
==Audio Samples of Digital Signals==
 
If you want to be able to identify a signal by sound, or by viewing it on an audio display (many digital decoding programs - and some
 
soundcard programs - have this ability), then these sites are a good place to start
 
<br>
 
* [http://www.bartg.org.uk/modesamples.asp British Amateur Radio Teledata Group Mode Samples]
 
* [http://www.w1hkj.com/FldigiHelp-3.21/Modes/index.htm Digital Modes - Sight & Sound]
 
* [http://www.bcar.us/digsig.htm Digital Signal Audio Reference]
 
* [http://det.bi.ehu.es/~jtpjatae/sound.html Eduardo Jacob's Home Page- Sound Files]
 
* [http://www.w1hkj.com/FldigiHelp-3.21/Modes/index.htm fldigi samples of decodeable modes]
 
* [http://hfradio.org.uk/html/digital_modes.html G4UCJ's Radio Website]
 
* [http://sferix.myweb.hinet.net/hfasia/ HF Asia Sound Files]
 
* [http://www.iarums-r1.org/iarums/sound/main.html IARU Monitoring System Region 1 Sound Files]
 
* [http://www.jvcomm.de/soundframee.html JVCOMM32 Sound Samples]
 
* [http://www.kb9ukd.com/digital/ KB9UKD Digital Modes Samples]
 
* [http://www.qsl.net/lu8mbr/digimodos.htm LU8MBR Digimodos (Spanish)]
 
* [http://www.mixw.net/index.php?j=signals MixW digital signal examples]
 
* [http://f1ult.free.fr/DIGIMODES/MULTIPSK/digimodesF6CTE_en.htm MultiPSK - Digital Mode Samples]
 
* [http://www.nonstopsystems.com/radio/radio-sounds.html NonStop Systems Radio Sound Samples]
 
* [http://signals.radioscanner.ru/base/ Signals RadioScanner RU Signal Samples] (page partially in Russian)
 
* [http://signals-analysis.blogspot.com/ Signals Analysis Blog]
 
* [http://www.sigidwiki.com/wiki/Signal_Identification_Guide Signal Identification Guide (wiki)]
 
* [https://www.youtube.com/user/FirstToken/videos Token's Audio Samples]  includes several digital signals
 
* [http://www.udxf.nl/modes.html UDXF Audio Samples]
 
* [http://wb8nut.com/digital/ WB8NUT Digital Information Page]
 
 
 
* [http://www.qsl.net/zl1bpu/ ZL1BPU Fuzzy Modes]
 
 
 
==Modes and Links==
 
* ALE (Automatic Link Establishment - or by it's other name, MIL-STD-188-141A, as well as several variants)
 
** The [[ALE]] page has a listing of all the packages that decode ALE.
 
** The [[ALE Networks]] page consolidates a listing of active ALE networks.
 
* [[HFDL]] misnamed HF Datalink, it's really an HF version of [[ACARS]]
 
* What is [[Link-11]]? 
 
* The Maritime service utilizes Sitor-B from certain stations in the US, and FAX (Fascimile) is used for weather charts. The use of FAX for photo transmissions has been long gone, contrary to what you might read in certain ham equipment distributors and old websites. Satellites took over that function years ago.
 
** [http://www.nws.noaa.gov/om/marine/hfsitor.htm USCG HF Sitor schedules]
 
** [http://www.nws.noaa.gov/om/marine/rfax.pdf NOAA Worldwide FAX Schedule] (PDF)
 
 
 
==Software==
 
* [http://www.chace-ortiz.org/umc/software.html Utility Monitoring Central]
 
* Here's Marius Rensen's popular [http://www.hffax.de HF FAX] site for FAX/SSTV information
 
 
 
==Slow Scan TV (SSTV)==
 
* What is [http://en.wikipedia.org/wiki/SSTV SSTV] (Slow Scan TV)?
 
* [http://www.barberdsp.com/ ChromaPix] by Silicon Pixels
 
* [http://ftv.3amsystems.com/ FTV]
 
* [http://www.pervisell.com/download/roote.htm JVComm32]
 
* [http://mixw.net/ MixW]
 
**[http://groups.yahoo.com/group/mixw/ MixW Yahoo group]
 
* [http://mmhamsoft.amateur-radio.ca/ MM Hamsoft] Home of MM-SSTV, and note that the most recent versions are Vista-compatible
 
** [http://groups.yahoo.com/group/MM-SSTV MM-SSTV Yahoo group]
 
* [http://mscan.com/ Mscan SSTV]
 
* [http://www.blackcatsystems.com/software/multimode.html MulitMode] for Macs
 
* [http://users.telenet.be/on4qz/ Ham Software for Linux] see QSSTV link
 
* [http://www.computer-int.com/rc.htm RadioCom]
 
* [http://www.barberdsp.com/w95sstv/w95dload.htm W95SSTV]
 
 
 
==Yahoo Groups and websites==
 
; Websites
 
* [http://mt-utility.blogspot.com/ Utility World Blog]
 
; Yahoo Groups
 
* [http://tech.groups.yahoo.com/group/cothen/ COTHEN]
 
* [http://groups.yahoo.com/group/HFmonitors/ HF Monitors]
 
* [http://groups.yahoo.com/group/udxf/ Utility DXers Forum (UDXF)]
 
 
 
[[Category:HF Topics]]
 

Latest revision as of 22:01, 14 May 2017

Welcome to the HF Digital Decoding article. While tuning around the HF bands, you are very likely to hear a variety of squawks, beeps and other sounds that, at first, defy description. While noise sources are a likely source (typical of HF), at least some will be some sort of digital signal.


Digital signals come in 2 basic flavors - those as used by the amateur radio community, and those used by organizations such as the military, aeronautical, maritime and several other users. While the modes used by amateur radio are, by both law and convention, never encrypted, there are several in the military and others that encrypt their signals so they can't be monitored by the casual listener. The challenge here is to find signals that are readable, or at least, where the user can be identified.

Please see the following articles for more information: