Talk:Radioteletype
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Could someone who knows adds some information on the history of RTTY, e.g. when it was first used? I know that Baudot codes have been around since the 1870s; is RTTY of similar provenance? -- Cabalamat 01:04, 25 September 2005 (UTC)
- User:Eyreland added a lengthy section named History but I removed it, as it seemed to be a copyvio ([1]). Mysid 10:35, 21 March 2006 (UTC)
- I've added some details to the history of RTTY. More to follow as I find time to research my files for original documents to reference. Wa3frp (talk) 16:00, 16 December 2007 (UTC)
[edit] Would a list of common/popular rtty frequencies/stations be appropriate?
Please discuss... 66.28.178.67 17:31, 27 September 2007 (UTC)
- It would certainly be good to include categories of stations, types of transmissions, modulation types, or long term stations and frequencies that have been published somewhere. Former stations such as news broadcasts are no problem. Original logs are out of place here because it is original research. It is best to format the information as text in paragraphs rather than a list. Graeme Bartlett 21:04, 30 September 2007 (UTC)
- There are very few non-encrypted RTTY stations today, most notable being the German Weather Service. If there is no objection, I shall add the frequencies and callsigns.
- Sv1xv (talk) 16:17, 7 January 2008 (UTC)
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- It is my opinion that this is useful information and should be posted. However, it also needs to be checked often and kept current. This is because no information is better than incorrect information. Be sure to also post the shift and speed. I believe that the German Weather Service uses 425 Hz shift and 50 baud. Wa3frp (talk) 12:41, 8 January 2008 (UTC)
[edit] How it works
I propose that this section is moved immediately before "Technical Specification". It must also be expanded to include a very brief description of parallel to serial conversion, numbers shift, start/stop bits. Information duplicated in "Technical Specification" should be removed.
Is there any information or refernece to the "6-bit ITA2" alphabet and the system using it ?
In addition to "RYRY..", the "THE QUICK BROWN FOX...." test sequence should be included.
Do you propose any other additions and changes?
Sv1xv (talk) 08:00, 11 January 2008 (UTC)
- These all all very good improvement ideas. The only reference that I've located so far on "six bit ITA-2" comes from http://lycos.com/info/baudot-code--characters.html?page=3 and I'd suggest that any reference to "...THE QUICK BROWN FOX..." also have a link to http://en.wikipedia.org/wiki/Pangram.
I just added a "Technical description" section, but did not yet touch the existing "How it works". Your comments please?
Sv1xv (talk) 19:41, 12 January 2008 (UTC)
WA3FRP, thanks for the corrections and improvements. Next step is to copy some information from "how it works" into "technical description" and then delete the former subsection. Sv1xv (talk) 09:53, 13 January 2008 (UTC)
The following block of text was merged with "Technical description" and then deleted:
| “ | RTTY uses a variety of different modulation methods, of which frequency shift keying is the most common.
The FSK RTTY signal starts at the teleprinter as groups of dc impulses, known as marks and spaces. Each group represents an alphanumeric character or a function. As the operator types characters and functions on the teleprinter, the connected originating transmitter's carrier is shifted by a predefined frequency, usually 170 or 425 Hz. At the receiving end, the shifted carrier is detected and the audio output is normally fed to an external Terminal Unit ("Demodulator") which converts the audio signal to dc impulses which operate the teleprinter. These FSK signals can be heard on a communications radio receiver equipped with a BFO (beat frequency oscillator), and have a "beedle-eeeedle-eedle-eee" sound, usually starting and ending on the high-pitched tone. The most common test-signal is a series of "RYRYRY" characters, as these form an alternating tone pattern exercising all bits and are easily-recognized. * Coding used is typically 5-bit ITA2 code (also known as the Baudot code), which is asynchronously with start and stop bits. * At least one common RTTY system uses 6-bit ITA2 character codes. * More modern systems use 7-bit or 8-bit codes, e.g. ASCII. Many RTTY operators had equipment which featured paper punch-tape readers. The operator would type the message on the TTY keyboard, which would punch the code into the tape. The tape could be re-done as desired, then transmitted at a steady, high rate, without typing errors. A tape could be reused, and in some cases - especially for use with ASCII on NC Machines - might be made of plastic or even very thin metal material in order to be reused many times. |
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Sv1xv (talk) 20:24, 13 January 2008 (UTC)
[edit] Slow by modern standards
The statements in this section are not very accurate, RTTY is not a very robust mode (SITOR-A and PACTOR perform much better) neither a very slow one (150 baud is not bad). Lack of error detection and correction is its main drawback. Most users did not change from RTTY to some other mode, they just abandoned HF radio links in favor of landline and satellite (press, AFTN, etc). I propose that this section is corrected and merged with "How it works".
Sv1xv (talk) 08:00, 11 January 2008 (UTC)
- I agree with your comments here as well.
