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




							    ===========================
							    MARITIME LF BAND SIMULATION
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OVERVIEW:

	Maritime LF band was popular in 1920s, 1930s. It became "obsolete" somewhere near 2WW because short wave instalations were 
	more and more common. Almost always LF installations were on bigger ships, often on passenger ships - antennae system was 
	really huge sometimes 300 meters long T antenna. Range was much better than MF but worse than HF. 



WORKING PROCEDURES:

	Calling channel was 143 kHz (wave 2100 meters).
	Working procedures were slightly different than 500 kHz. Coast Stations answered on its working frequencies, thus it wasnt 
	simplex channel like 500 kHz, but Coast Stations also announced traffic lists or meteo/navigational broadcasts on 143 kHz.

	Working channels: it was both duplex and simplex working scheme. It seems clear that some countries had it own national
	simplex waves but when foreign ship had assigned other channels (or by operational reasons like QRM, etc) only duplex 
	working was possible.

	General radiotelegraphic working procedures were slightly different in old times, starting signal '<' is commonly used,
	also some punctation and Q codes were other (for example QRH = my wave is...).



QTC OLD FORMAT:

	In those times Maritme Radiotelegrams were formatted in little bit other way than later, see example:

	< WCC de DAAC SS EUROPA 1    15 6/12 1647 = TEXT + DAAC K

	Starting Signal, Chatham Radio this is S/S EUROPA, we have radiotelegram number 1 for you. 15 words, 6th december at 1647 GMT = 
	= TXT + DAAC, over.
	
	For aircrafts and dirigibles which used Coastal Stations for communication while flights over sea, prefix SA was used instead of SS.



SIMULATION:

	Special 143 kHz Coastal Stations database was created, these stations were documented active on this waves but not all working 
	frequencies are implemented yet for all stations being called on 143 kHz. Currently it is 34 Coast Stations.

	Similiarily 143 kHz active ships database was created. Currently it counts 42 vessels.

	Also special database for ships working frequncies is established (source mainly: [1]). These are all real assigned frequencies
	for particular ship (or dirigible). This also include original GRAF ZEPPELIN working frequencies.

	Following ships working frequencies are in use:	
						
						========================================================================
						FREQ		constraits			remarks	
						========================================================================
						125.0		MIN 23-28 55-00					
						131.0		EVEN MINUTE					
						133.0		MIN 35-00											
						135.0		when PCH is not working								
						137.0		
						139.0		MIN 5-18									
						141.0			
						145.0		MIN 6-00
						147.0		NON 3rd MIN			(Italian wave)						
						149.0		OFF AIR/PLANNED	BRITISH NET	(British simplex wave)					
						151.0						intership wave 					
						153.0		when WCC is not working	
						155.0						
						157.0						
						158.0		0500-1500 1600-1800 1900-0400				
						159.0						
						160.0
						========================================================================



OTHER ITEMS SIMULATED:
	

1/ 143 kHz Coast Stations annoucements: 

	Currently only 3 are real skeds and you can switch to announced wave (GKU,VAS,WNY). Others are not original 
	and these are at 5th minutes (not all slots taken), their services arent simulated yet. These skeds will be 
	replaced gradually with original skeds. 
	

2/ 143 kHz normal ship-shore calling traffic: 

 	All the time but not 10th minutes.
	

3/ Meteo and navigational Traffic: 
	
	Mainly annoucements only. Few brodcasts are on air, see: wx_nx.txt


4/ Telegram traffic: 

 	Specilized function on ships working frequencies. Old procesures and message formatting.
	Still only 1 QTC is sent for compability with these times (will be expanded soon).
	

5/ Static traffic:

	Theres was a lot of static tfc in earlier versions but I'm trying reduce it.
	Static traffic has its advantages because its mainly real logged traffic, but its boring.  



6/ SP - Silent Periods:

	There was no SP on 143 kHz. But because ships were expacted to maitain watch on 500 kHz during SP, 
	I reduced traffic on LF working channels at 15-18 and 45-48 minutes (probability is 3 times less).



7/ QTE traffic:

	Some stations has been using 2100 m calling channel for gonio simplex purposes. This was typical 
	for those times, stadarization was no so strict as in further periods.


8/ Traffic lists:

	Special version of traffic lists was created, connected with LF vsl database (in fact it can be also
	connected with old vsl database, but this will be considered later). 
	See: tfc_lists.txt	


9/ Coastal Stations Working Channels:

	In recent version of RX0 special dynamic function for LF Coastal Stations was implemented and all
	static traffic already present on coastal working channels will be overtaken by this function. 
	Currently there is only scenario of calling/qsying and receiving telegram from sea. No shore-ship
	traffic yet. Will be developed gradually.


10/ Intership wave:
	
	151 kHz was dedicated intership wave. Currently only random calling simulated, no answer. Will be
	developing later.



SOURCES:

[1] Radio Service Bulletins, various
[2]