SP8WJT/HF8V			  			   - RED ARMY RADIOTELEGRAPH SIMULATOR -						 SP8WJT/HF8V




							    ====================================
							    CALLING AND DISTRESS CHANNEL 500 kHz
							    ====================================



==================
OVERVIEW
==================
 
		500 kHz was most important maritime calling channel. Band X (MF CW) was basic band in times when VHF was not
		popular (untill late 1970s). Distress and navigational traffic played important role here, unlike on HF.

	  

==================
500 kHz SIMULATION
==================

		Generally one pair (entry) is always used for background (lowest QSA) and is not intended to copy. 
		Other 1-2 entries used for normal tfc but during annoucements even 5 is possible (I had reduced it
		by means of even/odd day in some cases.) 
		
		

Following aspects were simulated:


1/ 500 kHz annoucements of WX/NX/TFC LIST

	A lot of them are implemented, practically every hour at 00, 10, 18, 30, 48.... minutes (1 minute window).
	Just listen and QSY to annouced freq. All annouced TFC LISTS can be heard on their annouced freq (in 5 minute window).
	Same with WX/NX too, but only small part of them carry real trafic, all other will send constatly CQ/CS/service and waiting signal. 
	See wx_nx.txt for skeds.


2/ Navigational Traffic: warning signals TTT and urgency signals XXX 

	Some 10 scenarios are used. All static transmissions, real stories found on various R/O sites, logs, etc.  


 3/ Static opchat/QSO examples

	Currently 16 real scenarios. All static, R/Os stories, logs, etc...
 

4/ Normal ship-shore calling traffic 

 	Some 25 scenarios of calling with various services and traffic. All dynamic. 
	
	Main VSL databese is used and special MF coastal stations database with some 100 stations in it. All of them has assigned 
	their working QSW and QSX MF freqs.

	Do not QSY to exchanged frequencies because this feature is not simulated yet (you will hear random ships there).
	I will try simulate this in the future, althought it is complicated, coz some technical problems appeared here. 
	Working freq can be already in use by the same coast station (broadcasts).

	There is no constraints in QSO, so some contacts can be 'strange'. This simulator is not about the history of maritime
	so I cannot create 100% true QSO table. Some ships played on all oceans and some on constant routes, which rarely changed.
	

5/ Ship to ship friendly QSO

	One dynamic scenario, also used on HF. It was forbidden to 'rag chewing' on 500 kHz but always happend. Can be heard also on 
	working channel 512 kHz where it was allowed. Some impossible contacts can happend (too long distances for MF or North Korean 
	QSO with US Imperialists, etc).
	

6/ Small coast stations CQ	
	
	There is special database for very small coast stations which had assigned only one frequncy, namely 500 kHz.
	Most of them are pre 1939 stations. Currently no traffic is assigned to these stations, just CQ.  
	A lot of them were in fact spark stations, and special flag was assign these stations. In the future this stations will
	be simulated with spark sound. 
 
	Before 1945 many small coast stations were 500 kcs only equipped and used this wave both as calling and working channel (QSS NO).
	Later on this was strictly forbiden, because traffic was too heavy on 600 m.
	
	This is little bit not compatible with further shape of 500 kHz and can be switched off by HIST button.


7/ Distress Traffic
	
	See: sos.html



8/ SP - Silent Periods

	15-18 MIN 
	45-48 MIN 

	With some opchat in it from [1].



9/ Naval traffic

	1930s USN traffic and its origial procedures.

	This is little bit not compatible with further shape of 500 kHz and can be switched off by HIST button.



10/ SVVV Collective

	At the moment calling only from greek merchant fleet. (looking for QSO examples in greek). Dynamic function.



11/ Band X only equipped ships

	Some ships were MF CW equipped only (greedy capitalistic owners, coastal service, etc).
	Thus specialiazed database was created linked with its usual coast stn according to historical data.


12/ QSP?

	Its often happend that band X only equipped ships asked band Z equipped ships (raher than W and Y)
	for relying their communication on HF. Thus band X database was used for QSP? feature. Althought I'm not
	sure if whole database is 100% compatible because of coastal ships like EARx (Melilla-Malaga route, etc),
	which probably were always in range of spanish coast stations, but its a small detail. 

	Under development - at the moment calling only.


==================
ERRORS, BUGS
==================

	Still many bugs can happen because simplex simulation algorithms are not so stable comparing to duplex.
	
	- Transmission Parametres losts (too low/high speed)
	- repeating of some transmissions
	- crash (when more than 5 signals appeared)

	I case of problems just restart RARS.




SOURCES:

[1] site of NMO ex operator
[2] http://www.radioalumni.ca/Pdf/TRC-12.pdf
[3] see maritime_linx.txt file