RED ARMY RADIOTELEGRAPH SIMULATOR

= Radiotelegraph Telecommunication Service =




Radio Service


No doubt Radio Service radiooperators were the best radiotelegraphists in whole history of radiocommunication, althought those from Coastal Stations were almost
equally good. I think main reason for this was huge traffic on their stations. After 2 WW there was 20,000 callsigns issued for fixed service stations (this included
aeronautocal stations) while only 7500 for seagoing ships. Huge stations (Radio Centres) has 30 or more transmitters and all has its own callsign or even
few callsigns for various relations. In other words it was huge Giant of Short Waves, Long Waves and Very Long Waves of those times. All these stations were
crowded on very small fixed bands and their signals were usually strong, 30 kW or more transmitters were used commonly and the better antennae ever invented
namely - rhombic antennas. They were receiving on not very sophisticated from todays point of view tube receivers without any quartz filters, with low sensivity,
selectivity, stability and dynamics, but owing high power and good antennas input signal on such receivers was fantastic.
Both A1 and F1 modulation was used, latter because of instability of voltage on huge Radio Centres.



Auto


To make traffic more fluent so called AUTO was used. It was high speed Morse sent and received in automatic means by automatic transmitters and undulators
Nevertheless as I found on old XQ radiotelegrams radiooperators often prefered manually sending of traffic. Why? Lets see at their typical work....
First they needed to punch huge load of for example 300 radiotelegrams on paper tapes, what was done with punch machine similiar to typewriter.
next, they called manually another station and transmitted tape on high speed. If there was no QRM it was fine buissnes as the call it.
But it was only half of job! Because now, receiving operator had to manually read all curves from undulator tape, dot by dot, and write it on telegram blanks!
So, good and high speed telegraphists often prefered transmit manually from blanks, while receiving operator was writing incoming telegram on blanks.
Very good radiooperators were able to works this way with speed up to 35 WPM.

This state of facts was changed when telex was introduced and then good telegraphists were phased out by Greedy Capitalists. Many small telecommunication
firms bancrupted at that time in capitalistic countries. Short Waves has changed. On empty spaces left by Telecommucation ITU established aeronautical
bands, more spectrum was assigned for Brodcasting. Era of Big Radiotelegraph Telecommunication ended.

Now lets see at specific of various bands:


VLF transmitters specific


VLF installations were really huge and costly one, but still, Radio Service was cheaper and more flexible than lying thousands kilometres of submarine cables.
It was long range radiocommunication. For some stations in some conditions it was practically whole globe (lets say GBR for example).
In other cases minimum 4000 miles where easily achived. There was weak point: atmospherics nearby receiving station (in such case another receiving station
can be used). VLF stations has been phased out by cheaper LF and HF installations and this process started near 1925 year.


LF transmitters specific


Used for local (up to 4000 km) communication. During 1920s to 1940s LF transnitters were real working horse of Radio Service. LF installations were
much cheaper than VLF and propagation was more stable than on HF installations. There was one weak point: atmospherics. When QRN occurred nearby receiving
station link was broken. In such case they could revert traffic via own HF transmitters or try via other station and/or land lines (which means tradffic
fees for other telecommunication organisation). Nevertheless after 2WW LF telecommunication was slowly phased out by HF.


HF transmitters specific


HF installations were even more cheaper than LF but link was less stable because of HF propagantion disturbances.
Such periods of total fading were rare and traffic was usually reverted via other HF routes or via LF and VLF transmitters in earlier periods.
HF transmitters has been phased out by satellite communication, this process started in 1960s.


Coding traffic


Short Waves were fascinating at that times because a lot of traffic was sent in plain, one could copy radiotelegrams from whole world (it was a kind of internet
of those times). I remember end of this era on Maritime bands when russiam stations were still active and dozens of telegrams were sent in so called blind
traffic skeds.

Some methods for traffic coding has been used by some stations, simple method was inverting space/mark signals (negative wave) it was easy to decode by
inverter but impossile to understand by ear. Huge stations also used so called multiplex where 2 o more channels were created in the same channel by
redefining dot, dashes and spaces. Such traffic is simulated as example only on british stations.


Working procedures


Working procedures was quite different comparing to other services, for example Coastal Stations. I think bigger difference was AUTO systems,
and connected with AUTO commercial Z codes. As I found in historical loggings many capitalistic stations has been using cable callsigns

For example London called New York in this manner:

NY DE LN K

what was clearly againt ITU resolutions about proper identification of all radio transmitters. I think reason for this was many callsigns of transmitters at huge
Radio Centres and fact it was post office radioperators (see GPO operators at work here.) who also worked on submarine cables on such calligns.
Also sometimes they were keying few TX and in such case they should use slashed callsigns like this: GBR/GIA etc... what was complicated.

During my reaserach i found that most popular codes used by telecomucation were: RQ, ZSU, ZFB and similiar because of common problem with collated messages:

ZSU L/R ABC456 .... (signal unsuable, last received: telegram prefix, telegram number)

or

RQ ABC456 .... (request: telegram prefix, telegram number)

etc...

According to some source, some stations at the beginning of sked exchanged some kind of traffic list, number of telegrams to send, how many tapes to send , etc
This feature is still not simulted in RARS, I looking for more info.


Dotters


Rapid dots were sent by some stations (dotters, reversals) on calling tapes for adjustment of high speed receiving equipment.
This was typical for pre telex period. At least I know french stations used it commonly. Receiving equipment needed to be adjusted better than 60/40
dots/dashes weight. You can read more about it here: [11].


Simulation


Currently simulation at almost all telecommunication stations are made by one common functions with 30 senarios of opchat and some 30 radiotelegrams.
In reality I think 95% of operational time was used by AUTO and maybe 5% for opchat. Outside operational time calling tapes are iddling
with typical VVV or QRA tapes. Latter was american standard recommended by FCC.

Please remember that during 1920s radiotelegrams has been transmitted manually, in 1930s AUTO was introduced, and in 1940s telex was introduced
In another words Radiotelegraphy slowly was withdrawn from Telecommunications, while RARS simulates all periods.

While telecom_opchat_dx() is used for typical duplex telecom simulation, already first specialized functions were introduced: russian_ptt() with russian opchat
or ufc( ) for TRT.. While researching about specific network this will be customized, although it is very difficult to find informations what was operating manners of radiotelegraphists 100 years ago, but I'm synthetising such picture from virtually thosands of documents found in various archives, logs, descriptions, etc.







SOURCES:

[1] TELEGRAPH REGULATIONS (Revision of Cairo, 1938), annexed to the INTERNATIONAL TELECOMMUNICATION CONVENTION, Madrid, 1932
[2] Report of the Federal Radio Commisission, 1931
[3] List of Marconi wireless stations
[4] Imperial Wireless Chain
[5] Radio Service Bulletins, various
[6] Commercial and Government Radio Stations of the United States, Washington, 1923
[7] Jurisdiction of Radio Commission: Hearings ... Seventieth Congress, First Session, United States. Congress. House. Committee on Merchant Marine and Fisheries, 1928
[8] European Transportation Survey: Telecommunications in Norway
[9] Hearings, United States. Congress. Senate. Committee on Commerce, 1959, (Merger of International Telegraph Carriers)
[10] TICOM D-69
[11] Radio Engineering Handbook, New York, 1950
[12] TELE-TALES ! - A glance at the great Central Telegraph Office in London, 1932
[13] Commercial Short Wave Wireless Communications, The Marconi Review no.14



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