Morse code timing

[Hardy Heinlin]

Hello,

the code consists of five elements, each element is x time units long:

- short tone: 1 unit long
- long tone: 3 units long
- pause between tones: 1 unit long
- pause between letters: 3 units long
- pause between words: 7 units long

1. Does anybody know if the duration of one unit is standardized world-wide (for avionics)?

I guess it is.

2. Does anybody know the duration of one unit, or can somebody with a navaid receiver measure the 7-unit pause between words?

(I heard it a million times myself, but I don't want to rely on my memory, and I don't have a receiver.)


Cheers,

|-|ardy

[Jamie]

depends on what you are identing? ILS/VOR/ADF I can record a few tomorrow...

[Hardy Heinlin]

Any navaid type actually. I assume the time units (pauses) are always the same, just the frequency of the tone (pitch) varies from type to type (e.g. 400 Hz for OM, 1300 Hz for MM).

Any sound sample would be helpful, thank you!


Cheers,

|-|ardy

[Hardy Heinlin]

While we are at navaids ... VHF stuff in magenta, NDBs in orange:





(Exploring the Russian NDB world is like seacrhing for double stars in the sky ...)

Please note that these maps are just basic orientation tools for the Instructor, they're not going to replace flight planning programs or Electronic Flight Bags, that would be beyond the scope of PSX (whose main purpose remains flight simulation).


Cheers,

|-|ardy

[Hardy Heinlin]

We're living in the GPS era, but there are still over 100 airway markers on the planet. Here are some displayed (orange) together with Morse code:




Skoll,

|-|ardy

[Jamie]

Got some recordings from Minsk-2 will make some today in Helsinki and Vienna.

Link will follow! Or maybe drop me an email: pilot at itsjamie.com

[Hardy Heinlin]

Link would be fine, Jamie, thank you!

Is itsjamie your web site, are you also an IT engineer?


Cheers,

|-|ardy

[martin]

"It's Jamie" ?  

[Jamie]

yep ITs Jamie Long story, all started with this FSFAN (Dutch page) looong long time ago. See if you can spot me . Worked for more than 10 years as programmer, MCSE/Unix engineer, etc etc. Now flying for AUA (Austrian Airlines). But will be on severe part-time from July on due to economic situation hence the ITs Jamie startup.

Anyway, the files
Had no time to record 'European' airports today, we had delays all the way, just got back from AMS but able to do more tomorrow.

Download link
Hope it helps, recorded with iphone in the cockpit (F100). Please say if you need it different!

rgrds Jamie

[Hardy Heinlin]

Thanks a lot!

Hey, many of the Dutch names on that first photo sound familiar to me. That's from 1994, when CompuServe was the main platform for all flight simmers and aviators ... I uploaded my first FS freeware panel in that year ...


Cheers,

|-|ardy

[Jamie]

Indeed Compuserve I remember BlueWave reader to download the FIDO posts.

Let me know if you need different recordings! I make some more for you to compare. Cheers!

[Hardy Heinlin]

Your recordings are perfect, thanks! The time units can easily be measured with them. The only question remaining is if the units are standard world-wide. But I bet they are.

|-|

[Hardy Heinlin]

Something just came to mind: There may be some timing variation from country to country, but the tolerance must have a certain limit. Why? Because the decoder which automatically converts the audio tones to alphanumeric text for the EFIS surely needs some average standard for its recognition algorithm.

|-|


Edit: Ha! I just read this in an AOM: "Due to the large variation in ... identification signals around the world, the automatic decoding feature will occasionally be unable to ... (e.g. the localizer "KL" may be decoded as "KAI" ...)"

No wonder:

L = ._..
A = ._
I = ..

[Jamie]

Hi well I promised to record some more from the various countries I fly, unfortunately I'm off on holiday for this month sorry!

[effte]

For an ILS, VOR and NDB: The speed of transmission should be such that it corresponds to roughly seven words per minute.

For a DME, the identification depends upon whether the DME is associated with another facility (ILS/VOR) or not. For an associated DME, the DME ident should be synchronized with the associated facility such that the associated facility transmits its identification three times in a 40 second timeframe while the DME transmits its identification one time. The speed of the morse code should be at least corresponding to a rate of 6 words per minute.

For an ILS and DME: the dots are to have a duration of 0.1 to 0.160 seconds, with the dashes three times as long. The pause between dots/dashes should be as long as a dot, plus/minus maximum ten percent. No less than three dots pause between letters. In my experience, VORs and NDBs don't differ much even though they don't have the same exacting specs.

Outer markers should transmit two dashes/second. Middle markers alternating dots and dashes, dots at a rate of six per second and dashes at a rate of 2 per second. Inner markers continuous dots at a rate of 6/second.
 
That's the ICAO requirements, and I'd be surprised if there are states which have bothered to make significant exceptions.

Edit: Hardy, if you contact me on the email address provided I may be able to help out ever so slightly.

[Hardy Heinlin]

Thank you for the help! Now I think I have all required details.


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