Public Telegraph Network

IntroductiontoTelegramNetwork

TelegramNetworkisatelecommunicationsnetworkthatopenstelegramservicesforthetransmissionoftext,images,photos,documentsandotherinformation.Itisacommunicationnetworkthatconnectsthetelegraphofficeandtheuser'stelegraphequipmentandmakesnotifications.Telegraphcommunicationnetworkscangenerallybedividedintotwotypes:publictelegraphcommunicationnetworksandusertelegraphcommunicationnetworks.Amongthem,thepublictelegraphcommunicationnetworkmeansthatthesendersendsthemessagetothecorrespondingsendingoffice,andthesendingofficesendsthemessagetothereceivingofficethroughtheelectricsignal,andthereceivingofficesendsthemessagetotherecipient;usertelegramThecommunicationnetworkreferstothewayinwhichtheuserconnectsthecommunicationlinewiththesendingequipmentinhishand,andsendsthemessagetotherecipientbyhimself.

Accordingtothedifferentnatureoftheopenservicesofthetelegraphnetwork,thetelegraphnetworkisdividedintoapublictelegraphnetworkandausertelegraphnetwork.Inourcountry,thepublictelegraphnetworkandtheusertelegraphnetworkaretwoindependentandmutuallycommunicatingtelegraphnetworks.

Thetelegraphnetworkconsistsoftelegraphterminalequipment,telegraphtransmissionequipmentandtelegraphexchangeequipment.

Thecontentofthepublictelegraphnetwork

Thepublictelegraphnetworkmainlyconductslong-distancetranscriptcommunication.Duetotheallowabledelayofdelegation,thecentralizedforwardingmessageexchangemethodshouldbeadopted.Inaddition,thechannelutilizationrateofthetelegramismuchhigherthanthatofthetelephone,anditismoreappropriatetoadoptalow-levelnetwork.Afterthemanualtransmissionstage,mycountryhasrealizedautomatictelegraphexchange(referredtoasautomatictransmission)nationwide.SinceDecember1985,atwo-levelexchangesystemhasbeenimplemented.Thenetworkhasafirst-levelswitchingcenterandasecond-levelswitchingcenter.Theterminalequipmentismainlylocatedinthebureauswherethecountytelegraphbureausandswitchingcentersarelocated.Generally,two-levelswitchingcentersarelocatedinsomelargecitiesandprovincialcapitals,andtelegraphswitchingequipmentadoptsaprogram-controlledautomatictransmissionsystem,andonlyafewprovincialcapitalsaresecond-levelswitchingcentersandone-levelswitchingcenters.Thereisanetworkstructurebetweenthefirst-levelswitchingcenters;thefirst-levelswitchingcentertothesubordinatesecond-levelswitchingcenter,andthesecond-levelswitchingcentertothesubordinateterminalareallinastarstructure.Betweenanytwoswitchingcenters,aswellasbetweentheswitchingcenterandnon-ownedterminals,dependingonthetrafficvolume,itisnecessarytosetuphigh-efficiencydirectreportingroutes.Thefirst-levelswitchingcenternotonlyundertakestheswitchingoftheterminalstowhichthecenterbelongs,butalsoundertakesthetandemconnectionofthesecond-levelswitchingcentersintheareaandthetransferwithotherfirst-levelswitchingcenters.Thesecondaryswitchingcenterisresponsiblefortheswitchingoftheterminalsbelongingtothecenterandthetransferwithotherswitchingcenters.Telegramcommunicationbetweenthetwoterminalsfarthestrequiresatmost4switchingcenterstoexchangemessages.

Inaddition,someregionalpostofficesinthepublictelegraphnetworkhaveadoptedtelegraphdividerstoautomaticallydisperseandconcentratethetelegramssentandreceivedbytheterminalequipmentofthebranchofficesofthebureau.Intermsoffunction,thetelegraphdiversitydeviceisaswitchingdevice,butitisnotaswitchinglevelinthenetworkstructure.

mycountry'spublictelegraphnetworkalsohasanentryandexitbureautocommunicatewiththeinternationalpublictelegraphnetworktotransferinternationaltelegrams.

Theprogram-controlledautomatictransmissionsysteminthepublictelegraphnetworkimplementsstorageandforwardingforeachtelegram.Oncetherearetoomanytelegramsonacertainoutputroutethatexceedthetransmissioncapacityofthetelegram,thetransmissioncanbepostponedThestoredlower-leveltelegramswillnotbeforwardeduntilthetelegramisfree.Therefore,thepublictelegraphnetworkhastheabilitytodelaythepeakloadduringbusyhours.